vapor-dominated geothermal systems: Topics by Science.gov

Sample records for vapor-dominated geothermal systems

Hydrogeologic controls on saturation profiles in heat-pipe-like hydrothermal systems: numerical study

NASA Astrophysics Data System (ADS)

Pervin, Mollika; Ghergut, Iulia; Graf, Thomas; Peche, Aaron

2016-04-01

Most geothermal reservoirs are of the liquid-dominated type, and their unexploited-state pressure profile approximately follows the hydrostatic gradient. In very hot liquid-dominated systems, temperature typically follows a boiling-point-for-depth (BPD) relationship. By contrast, vapor-dominated systems exhibit (in their unexploited state) surprisingly small vertical gradients of temperature and pressure, such that a constantly high temperature is encountered over a large vertical thickness, while their pressure approximately follows vapour pressure, pvap(T°). This implies that (Pruess 1985, Truesdell and White 1973): (i) for a vapor-dominated reservoir to exist, it must be sealed laterally - otherwise it would be flooded by neighboring groundwaters with hydrostatic p profile, and (ii) liquid water should somehow be present in the whole system - otherwise p values would not be constrained by the pvap(T°) relationship for water. Historically, one of the most puzzling aspects of vapor-dominated systems was the large amount of heat flowing upwards, while vertical T° gradients remained negligible. This mechanism was deemed as 'heat pipe'(HP) (Eastman 1968): In the central zone of a vapor-dominated system, both vapor and liquid are mobile; vapor flows upwards, condenses at shallower depth, and the liquid condensate flows downwards. Due to the large amount of latent enthalpy released in vapor condensation, the vapor-liquid counter-flow can generate large rates of heat flow with negligible net mass transport (Pruess 1985). In order to be able to exploit two-phase (including vapor-dominated) reservoirs in a sustainable manner, one first needs to understand the conditions under which a two-phase (or a vapor-dominated) system has evolved naturally, and which have led to its present (quasi-) steady undisturbed state. Past studies have found that HP can exist in two distinct states, corresponding to liquid-dominated and vapor-dominated p profiles, respectively. Within this work, we explore some mechanisms and geologic controls that can lead to the formation of extensive vapor-dominated zones within a two-phase system. In particular, we investigate the effect of vertical heterogeneity of permeability (stratified reservoir, containing a permeability barrier) on the liquid water saturation profile within a modified HP model. Though in field observations liquid water has been directly encountered only within the condensation zone at reservoir top, it was speculated that large amounts of liquid water might also exist below the condensation zone. This is of great practical significance to the exploitation of vapor-dominated reservoirs, as their longevity depends on the fluid reserves in place. Within this work, we demonstrate by numerical simulations of a modified HP model that high values of liquid water saturation (>0.8) can prevail even far below the condensation zone. Such findings are useful as a baseline for future calculations regarding the economic exploitation of vapor-dominated systems, where premature productivity drop (or dry-out) is the main issue of concern. References: Eastman, G. Y:, 1968: The heat pipe. Scientific American, 218(5):38-46. Preuss, K. A., 1985: A quantitative model of vapor-dominated geothermal reservoirs as heat pipes in fractured porous rock, Transactions, Geothermal Resources. Council, 9(2), 353-361. Truesdell, A. H., and White, D.E. 1973: Production of superheated Steam from Vapor- dominated geothermal reservoirs. Geothermics, 2(3-4), 154-173
The evolution of volcano-hosted geothermal systems based on deep wells from Karaha-Telaga Bodas, Indonesia

USGS Publications Warehouse

Moore, J.N.; Allis, R.G.; Nemcok, M.; Powell, T.S.; Bruton, C.J.; Wannamaker, P.E.; Raharjo, I.B.; Norman, D.I.

2008-01-01

Temperature and pressure surveys, fluid samples, and petrologic analyses of rock samples from deep drill holes at the Karaha - Telaga Bodas geothermal field on the volcanic ridge extending northward from Galunggung Volcano, West Java, have provided a unique opportunity to characterize the evolution of an active volcano-hosted geothermal system. Wells up to 3 km in depth have encountered temperatures as high as 353??C and a weakly altered granodiorite that intruded to within 2 to 3 km of the surface. The intrusion is shallowest beneath the southern end of the field where an acid lake overlies a nearly vertical low resistivity structure (<10 ohm-m) defined by magnetotelluric measurements. This structure is interpreted to represent a vapor-dominated chimney that provides a pathway to the surface for magmatic gases. Four distinct hydrothermal mineral assemblages document the evolution of the geothermal system and the transition from liquid- to vapor-dominated conditions. The earliest assemblage represents the initial liquid-dominated system generated during emplacement of the granodiorite between 5910 ?? 76 and 4200 ?? 150 y BP. Tourmaline, biotite, actinolite, epidote and clay minerals were deposited contemporaneously at progressively greater distances from the intrusive contact (assemblage 1). At 4200 ?? 150 y BP, flank collapse and the formation of the volcano's crater, Kawah Galunggung, resulted in catastrophic decompression and boiling of the hydrothermal fluids. This event initiated development of the modern vapor-dominated regime. Chalcedony and then quartz were deposited as the early low salinity liquids boiled (assemblage 2). Both vapor- and liquid-rich fluid inclusions were trapped in the quartz crystals. Liquid-rich fluid inclusions from the southern part of the field record salinities ranging from 0 to 26 weight percent NaCl- CaCl2 equivalent and locally contain fluorite daughter crystals. We suggest, based on temperature-salinity relationships and evidence of boiling, that these fluids were progressively concentrated as steam was lost from the system. However, mixing with fluids derived from the underlying intrusion or generated during the formation of acid SO4 water on the vapor-dominated chimney margins could have contributed to the observed salinities. As pressures declined, CO2- and SO4-rich steam-heated water drained downward, depositing anhydrite and calcite (assemblage 3) in the fractures, limiting further recharge. Fluid inclusions with salinities up to 31 weight percent NaCl equivalent were trapped in these minerals as the descending water vaporized. The final assemblage is represented by precipitates of NaCl, KCl and FeClx deposited on rock surfaces in portions of the vapor-dominated zone that boiled dry. Vapor-dominated conditions extend over a distance of at least 10 km and to depths below sea level. Deep wells drilled into the underlying liquid-dominated reservoir in the northern and central part of the volcanic ridge produce low salinity fluids representing recent recharge of meteoric and steam-heated water. The evolution of volcanic-hosted vapor-dominated geothermal systems can be described by a five stage model. Stage 1 involves the formation of an over-pressured liquid-dominated geothermal system soon after magmatic intrusion. In Stages 2 and 3, pressures progressively decrease, and a curtain of steam-heated water surrounding a magmatic vapor-dominated chimney at 350??C and 14 ?? 2 MPa develops. The relatively low pressure near the base of the chimney causes liquid inflow adjacent to the intrusion and the development of a secondary marginal vapor-dominated zone. In Stage 4, the magmatic vapor discharge from the intrusion becomes small, vapor pressure declines, and the secondary vapor-dominated zone expands above the intrusion. In Stage 5, the vapor-dominated zone floods because heat from the intrusion is insufficient to boil all liquid inflow. A more common, liquid-dominated volcanic-hosted system the
Heavy metal contamination from geothermal sources.

PubMed Central

Sabadell, J E; Axtmann, R C

1975-01-01

Liquid-dominated hydrothermal reservoirs, which contain saline fluids at high temperatures and pressures, have a significant potential for contamination of the environment by heavy metals. The design of the power conversion cycle in a liquid-dominated geothermal plant is a key factor in determining the impact of the installation. Reinjection of the fluid into the reservoir minimizes heavy metal effluents but is routinely practiced at few installations. Binary power cycles with reinjection would provide even cleaner systems but are not yet ready for commercial application. Vapor-dominated systems, which contain superheated steam, have less potential for contamination but are relatively uncommon. Field data on heavy metal effluents from geothermal plants are sparse and confounded by contributions from "natural" sources such as geysers and hot springs which often exist nearby. Insofar as geothermal power supplies are destined to multiply, much work is required on their environmental effects including those caused by heavy metals. PMID:1227849
Heavy metal contamination from geothermal sources.

PubMed

Sabadell, J E; Axtmann, R C

1975-12-01

Liquid-dominated hydrothermal reservoirs, which contain saline fluids at high temperatures and pressures, have a significant potential for contamination of the environment by heavy metals. The design of the power conversion cycle in a liquid-dominated geothermal plant is a key factor in determining the impact of the installation. Reinjection of the fluid into the reservoir minimizes heavy metal effluents but is routinely practiced at few installations. Binary power cycles with reinjection would provide even cleaner systems but are not yet ready for commercial application. Vapor-dominated systems, which contain superheated steam, have less potential for contamination but are relatively uncommon. Field data on heavy metal effluents from geothermal plants are sparse and confounded by contributions from "natural" sources such as geysers and hot springs which often exist nearby. Insofar as geothermal power supplies are destined to multiply, much work is required on their environmental effects including those caused by heavy metals.
Open Questions on the Origin of Life at Anoxic Geothermal Fields

PubMed Central

Mulkidjanian, Armen Y.; Bychkov, Andrew Yu.; Dibrova, Daria V.; Galperin, Michael Y.; Koonin, Eugene V.

2014-01-01

We have recently reconstructed the ‘hatcheries’ of the first cells by combining geochemical analysis with phylogenomic scrutiny of the inorganic ion requirements of universal components of modern cells (Mulkidjanian et al.: Origin of first cells at terrestrial, anoxic geothermal fields. Proc Natl Acad Sci USA 2012, 109:E821–830). These ubiquitous, and by inference primordial, proteins and functional systems show affinity to and functional requirement for K+, Zn2+, Mn2+, and phosphate. Thus, protocells must have evolved in habitats with a high K+/Na+ ratio and relatively high concentrations of Zn, Mn and phosphorous compounds. Geochemical reconstruction shows that the ionic composition conducive to the origin of cells could not have existed in marine settings but is compatible with emissions of vapor-dominated zones of inland geothermal systems. Under anoxic, CO2-dominated atmosphere, the ionic composition of pools of cool, condensed vapor at anoxic geothermal fields would resemble the internal milieu of modern cells. Such pools would be lined with porous silicate minerals mixed with metal sulfides and enriched in K+ ions and phosphorous compounds. Here we address some questions that have appeared in print after the publication of our anoxic geothermal field scenario. We argue that anoxic geothermal fields, which were identified as likely cradles of life by using a top-down approach and phylogenomics analysis as a tool, could provide geochemical conditions similar to those which were suggested as most conducive for the emergence of life by the chemists who pursuit the complementary bottom-up strategy. PMID:23132762
Collective phenomena in the early stages of relativistic heavy-ion collisions

NASA Astrophysics Data System (ADS)

Ryblewski, Radoslaw

Geophysical signatures of volcano-hosted geothermal systems in Indonesia are compiled and synthesized. Parameters include electrical resistivity, seismicity, downhole logging, and pressure/temperature data; temperature and pressure states of systems are simulated through numerical models. The systems are Sungai Penuh, Hululais, Lumutbalai, Ulubelu, Kamojang, Kotamobagu, Tompaso, and Lahendong. The general resistivity structure of the systems comprises a vertical conductor under the volcano peak (<10 ohm.m), a lateral conductor under the volcano flank (<10 ohm.m), and an intermediate resistivity zone under the lateral conductor. Background formations are generally resistive with a resistivity >70 ohm.m. The vertical conductor is the expression of either an active or inactive volcanic neck / magmatic chimney. The lateral conductor is the claycap of the geothermal system containing an argillic alteration zone that keeps the hot fluids and the heat inside the reservoir. The topography of the volcano dictates the hydrology and shapes the extent of the lateral conductor. The hydrothermal fluids themselves are kept within the intermediate resistivity region, 10--60 ohm.m for a liquid-dominated system, and up to 100 ohm.m for a vapor-dominated system, preferably with the temperature of 200--300 ° C. On the margins, the reservoir may have either sharp or diffuse contact with the background or the claycap; vapor-dominated systems have a sharp contact. A diffuse contact is usually associated with a gradational change in temperature, with temperature reversal at depth. The caprock of a geothermal system has an aseismic character possibly due to its ductile behavior from the clay and from its low permeability structure. The low permeability property impedes liquid movement and flashing that could induce seismicity. The propylitic reservoir is seismogenic due to less clay content and its high permeability that promotes liquid movement and flashing into steam which induces seismicity. Modeling studies suggest that the most favorable permeability configuration for a vapor-dominated reservoir similar to Kamojang contains a caprock with the permeability of 3 x 10 -16 m2 accompanied with a recharge region/hostrock having the permeability of 10-18 m2 to 10-17 m2. A heat flow of 8 MW/km 2 for 9 kyr is the minimum combination to produce a thick vapor-dominated zone (> 1000 meter) in a 2.8 km thick reservoir with the permeability of 10-13 m 2. Model simulations are produced that reach steady state at 10.7 kyr, with 38--40 bar and 250--252 ° C reservoir yielding a heatloss of 90 MW and 35 kg/s of steam escaping from the reservoir. This study provided an unusual opportunity to characterize and model volcano-hosted geothermal systems.
Production of superheated steam from vapor-dominated geothermal reservoirs

USGS Publications Warehouse

Truesdell, A.H.; White, D.E.

1973-01-01

Vapor-dominated geothermal systems such as Larderello, Italy, The Geysers, California, and Matsukawa, Japan yield dry or superheated steam when exploited. Models for these systems are examined along with production data and the thermodynamic properties of water, steam and rock. It is concluded that these systems initially consist of a water and steam filled reservoir, a water-saturated cap rock, and a water or brine-saturated deep reservoir below a water table. Most liquid water in all parts of the system is relatively immobilized in small pores and crevices; steam dominates the large fractures and voids of the reservoir and is the continuous, pressure-controlling phase. With production, the pressure is lowered and the liquid water boils, causing massive transfer of heat from the rock and its eventual drying. Passage of steam through already dried rock produces superheating. After an initial vaporization of liquid water in the reservoir, the decrease in pressure produces increased boiling below the deep water table. With heavy exploitation, boiling extends deeper into hotter rock and the temperature of the steam increases. This model explains most features of the published production behavior of these systems and can be used to guide exploitation policies. ?? 1973.
Fracture Development within the Karaha-Telaga Bodas Geothermal Field, Indonesia

USGS Publications Warehouse

Nemcok, M.; Moore, J.N.; Allis, R.; McCulloch, J.

2002-01-01

Karaha-Telaga Bodas is a partially vapor-dominated geothermal system located in an active volcano in western Java. More than 2 dozen geothermal wells have been drilled to depths of 3 km. Detailed paragenetic and fluid-inclusion studies have defined liquid-dominated, transitional and vapor-dominated stages in the evolution of this system. The liquid-dominated stage was initiated by shallow magma intrusion into the base of the volcanic cone. Lava and pyroclastic flows capped a geothermal system. The uppermost andesite flows were only weakly fractured due to the insulating effect of the intervening altered pyroclastics, which absorbed the deformation. Shear and tensile fractures were filled with carbonates at shallow depths and by quartz, epidote and actinolite at depths and temperatures over 1km and 300??C. The system underwent numerous local cycles of overpressuring, which are marked by subhorizontal tensile fractures, anastomosing tensile fractures and implosion breccias. The development of the liquid system was interrupted by a catastrophic drop in fluid pressures. As the fluids boiled in response to this pressure drop, chalcedony and quartz were deposited in fractures having the largest apertures and steep dips. The orientations of these fractures indicate that the escaping overpressured fluids used the shortest possible paths to the surface. Vapor-dominated conditions were initiated within a vertical chimney over the still hot intrusion. As pressures declined these conditions spread outward. Downward migration of the chimney occurred as the intrusion cooled and the brittle-ductile transition migrated to greater depths. Condensate that formed at the top of the vapor-dominated zone percolated downward and lowsalinity meteoric water entered the marginal parts of the system. Calcite, anhydrite, and fluorite precipitated in fractures upon heating. A progressive sealing of the fractures occurred, resulting in the downward migration of the cap rock. In response to decreasing pore pressures in the expanding vapor zone, the fracture system within the vapor-dominated reservoir progressively collapsed, leaving only residual permeability, with apertures supported by asperities or propping breccia. In places, the fractures have completely collapsed where normal stresses acting on the fracture walls exceeded the compressive strength of the wall rock.
Gases in steam from Cerro Prieto geothermal wells with a discussion of steam/gas ratio measurements

USGS Publications Warehouse

Nehring, N.L.; Fausto, L.J.J.

1979-01-01

As part of a joint USGS-CFE geochemical study of Cerro Prieto, steam samples were collected for gas analyses in April, 1977. Analyses of the major gas components of the steam were made by wet chemistry (for H2O,CO2,H2S and NH3) and by gas chromatography (He,H2,Ar,O2,N2 and hydrocarbons). The hydrocarbon gases in Cerro Prieto steam closely resemble hydrocarbons in steam from Larderello, Italy and The Geysers, California which, although they are vapor-dominated rather than hot-water geothermal systems, also have sedimentary aquifer rocks. These sedimentary geothermal hydrocarbons are characterized by the presence of branched C4-6 compounds and a lack of unsaturated compounds other than benzene. Relatively large amounts of benzene may be characteristic of high-temperature geothermal systems. All hydrocarbons in these gases other than methane most probably originate from the thermal metamorphosis of organic matter contained in the sediments. ?? 1979.
Effects of capillary heterogeneity on vapor-liquid counterflow in porous media

NASA Astrophysics Data System (ADS)

Stubos, A. K.; Satik, C.; Yortsos, Y. C.

1992-06-01

Based on a continuum description, the effect of capillary heterogeneity, induced by variation in permeability, on the steady state, countercurrent, vapor-liquid flow in porous media is analyzed. It is shown that the heterogeneity acts as a body force that may enhance or diminish gravity effects on heat pipes. Selection rules that determine the steady states reached in homogeneous, gravity-driven heat pipes are also formulated. It is shown that the 'infinite' two-phase zone may terminate by a substantial change in the permeability somewhere in the medium. The two possible sequences, liquid-liquid dominated-dry, or liquid-vapor dominated-dry find applications in geothermal systems. Finally, it is shown that although weak heterogeneity affects only gravity controlled flows, stronger variations in permeability can give rise to significant capillary effects.
Probabilistic approach: back pressure turbine for geothermal vapor-dominated system

NASA Astrophysics Data System (ADS)

Alfandi Ahmad, Angga; Xaverius Guwowijoyo, Fransiscus; Pratama, Heru Berian

2017-12-01

Geothermal bussiness nowadays needs to be accelerated in a way that profit can be obtained as soon as reasonable possible. One of the many ways to do this is by using one of geothermal wellhead generating unit (GWGU), called backpressure turbine. Backpressure turbine can be used in producing electricity as soon as there is productive or rather small-scale productive well existed after finished drilling. In a vapor dominated system, steam fraction in the wellhead capable to produce electricity based on each well productivity immediately. The advantage for using vapor dominated system is reduce brine disposal in the wellhead so it will be a cost benefit in operation. The design and calculation for backpressure turbine will use probablistic approach with Monte Carlo simulation. The parameter that will be evaluated in sensitivity would be steam flow rate, turbine inlet pressure, and turbine exhaust pressure/atmospheric pressure. The result are probability for P10, P50, and P90 of gross power output which are 1.78 MWe, 2.22 MWe and 2.66 Mwe respectively. Whereas the P10, P50, and P90 of SSC are 4.67 kg/s/MWe, 5.19 kg/s/MWe and 5.78 kg/s/MWe respectively.
STABLE ISOTOPE GEOCHEMISTRY OF THERMAL FLUIDS FROM LASSEN VOLCANIC NATIONAL PARK, CALIFORNIA.

USGS Publications Warehouse

Janik, Cathy J.; Nehring, Nancy L.; Truesdell, Alfred H.

1983-01-01

In the Lassen vapor-dominated geothermal system, surface manifestations of thermal fluids at high elevations (1800-2500 m) include superheated and drowned fumaroles, steam-heated acid-sulfate hot springs, and low-chloride bicarbonate springs. Neutral high-chloride hot water discharges at lower elevations. Deuterium and oxygen-18 data establish genetic connections between these fluids and with local meteoric waters. Steam from the highest temperature fumarole at Bumpass Hell and water from the highest chloride hot spring have isotopic compositions corresponding to vapor-liquid equilibrium at 235 degree C. Carbon and sulfur isotope data suggest that the CO//2 and H//2S in the system did not entirely originate from magmatic sources, but probably include contributions from thermal metamorphism of marine sedimentary rocks. Observations suggest that carbon and sulfur isotope variations are useful indicators of gas reactions and flow paths in geothermal systems. Refs.
Water injection into vapor- and liquid-dominated reservoirs: Modeling of heat transfer and mass transport

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pruess, K.; Oldenburg, C.; Moridis, G.

1997-12-31

This paper summarizes recent advances in methods for simulating water and tracer injection, and presents illustrative applications to liquid- and vapor-dominated geothermal reservoirs. High-resolution simulations of water injection into heterogeneous, vertical fractures in superheated vapor zones were performed. Injected water was found to move in dendritic patterns, and to experience stronger lateral flow effects than predicted from homogeneous medium models. Higher-order differencing methods were applied to modeling water and tracer injection into liquid-dominated systems. Conventional upstream weighting techniques were shown to be adequate for predicting the migration of thermal fronts, while higher-order methods give far better accuracy for tracer transport.more » A new fluid property module for the TOUGH2 simulator is described which allows a more accurate description of geofluids, and includes mineral dissolution and precipitation effects with associated porosity and permeability change. Comparisons between numerical simulation predictions and data for laboratory and field injection experiments are summarized. Enhanced simulation capabilities include a new linear solver package for TOUGH2, and inverse modeling techniques for automatic history matching and optimization.« less
Physical factors determining the fraction of stored energy recoverable from hydrothermal convection systems and conduction-dominated areas

USGS Publications Warehouse

Nathenson, Manuel

1975-01-01

This report contains background analyses for the estimates of Nathenson and Muffler (1975) of geothermal resources in hydrothermal convection systems and conduction-dominated areas. The first section discusses heat and fluid recharge potential of geothermal reservoirs. The second section analyzes the physical factors that determine the fraction of stored energy obtainable at the surface from a geothermal reservoir. Conversion of heat to electricity and the use of geothermal energy for direct-heating applications are discussed in the last two sections. Nathenson, Manuel, and Muffler, L.J.P., 1975, Geothermal resources in hydrothermal convection systems and conduction dominated areas, in White, D.E., and Williams, D.L., eds., Assessment of the Geothermal Resources of the United States--1975: U.S. Geological Survey Circular 726, p. 104-121, available at http://pubs.er.usgs.gov/usgspubs/cir/cir726
Quantifying the undiscovered geothermal resources of the United States

USGS Publications Warehouse

Williams, Colin F.; Reed, Marshall J.; DeAngelo, Jacob; Galanis, S. Peter

2009-01-01

In 2008, the U.S. Geological Survey (USGS) released summary results of an assessment of the electric power production potential from the moderate- and high-temperature geothermal resources of the United States (Williams et al., 2008a; USGS Fact Sheet 2008-3082; http://pubs.usgs.gov/fs/2008/3082). In the assessment, the estimated mean power production potential from undiscovered geothermal resources is 30,033 Megawatts-electric (MWe), more than three times the estimated mean potential from identified geothermal systems: 9057 MWe. The presence of significant undiscovered geothermal resources has major implications for future exploration and development activities by both the government and private industry. Previous reports summarize the results of techniques applied by the USGS and others to map the spatial distribution of undiscovered resources. This paper describes the approach applied in developing estimates of the magnitude of the undiscovered geothermal resource, as well as the manner in which that resource is likely to be distributed among geothermal systems of varying volume and temperature. A number of key issues constrain the overall estimate. One is the degree to which characteristics of the undiscovered resources correspond to those observed among identified geothermal systems. Another is the evaluation of exploration history, including both the spatial distribution of geothermal exploration activities relative to the postulated spatial distribution of undiscovered resources and the probability of successful discoveries from the application of standard geothermal exploration techniques. Also significant are the physical, chemical, and geological constraints on the formation and longevity of geothermal systems. Important observations from this study include the following. (1) Some of the largest identified geothermal systems, such as The Geysers vapor-dominated system in northern California and the diverse geothermal manifestations found in Yellowstone National Park, are unique in North America and highly unlikely to have counterparts with equivalent characteristics among the systems comprising the undiscovered resources. (2) Historical geothermal exploration has been limited in both the effectiveness of techniques employed and spatial coverage, since most exploration has targeted areas associated with surface thermal manifestations in the most easily accessible lands. (3) As noted by other investigators, in general, the hottest and largest geothermal systems are those with heat sources arising from recent magmatic activity. Consequently, a larger fraction of the undiscovered resource is associated with those areas favorable to the formation of this type of geothermal system, including some relatively remote areas, such as the Aleutian volcanic arc in Alaska.
Controls on the Karaha-Telaga Bodas geothermal reservoir, Indonesia

USGS Publications Warehouse

Nemcok, M.; Moore, J.N.; Christensen, Carl; Allis, R.; Powell, T.; Murray, B.; Nash, G.

2007-01-01

Karaha-Telaga Bodas is a partially vapor-dominated, fracture-controlled geothermal system located adjacent to Galunggung Volcano in western Java, Indonesia. The geothermal system consists of: (1) a caprock, ranging from several hundred to 1600 m in thickness, and characterized by a steep, conductive temperature gradient and low permeability; (2) an underlying vapor-dominated zone that extends below sea level; and (3) a deep liquid-dominated zone with measured temperatures up to 353 ??C. Heat is provided by a tabular granodiorite stock encountered at about 3 km depth. A structural analysis of the geothermal system shows that the effective base of the reservoir is controlled either by the boundary between brittle and ductile deformational regimes or by the closure and collapse of fractures within volcanic rocks located above the brittle/ductile transition. The base of the caprock is determined by the distribution of initially low-permeability lithologies above the reservoir; the extent of pervasive clay alteration that has significantly reduced primary rock permeabilities; the distribution of secondary minerals deposited by descending waters; and, locally, by a downward change from a strike-slip to an extensional stress regime. Fluid-producing zones are controlled by both matrix and fracture permeabilities. High matrix permeabilities are associated with lacustrine, pyroclastic, and epiclastic deposits. Productive fractures are those showing the greatest tendency to slip and dilate under the present-day stress conditions. Although the reservoir appears to be in pressure communication across its length, fluid, and gas chemistries vary laterally, suggesting the presence of isolated convection cells. ?? 2006 CNR.
Discovering geothermal supercritical fluids: a new frontier for seismic exploration.

PubMed

Piana Agostinetti, Nicola; Licciardi, Andrea; Piccinini, Davide; Mazzarini, Francesco; Musumeci, Giovanni; Saccorotti, Gilberto; Chiarabba, Claudio

2017-11-06

Exploiting supercritical geothermal resources represents a frontier for the next generation of geothermal electrical power plant, as the heat capacity of supercritical fluids (SCF),which directly impacts on energy production, is much higher than that of fluids at subcritical conditions. Reconnaissance and location of intensively permeable and productive horizons at depth is the present limit for the development of SCF geothermal plants. We use, for the first time, teleseismic converted waves (i.e. receiver function) for discovering those horizons in the crust. Thanks to the capability of receiver function to map buried anisotropic materials, the SCF-bearing horizon is seen as the 4km-depth abrupt termination of a shallow, thick, ultra-high (>30%) anisotropic rock volume, in the center of the Larderello geothermal field. The SCF-bearing horizon develops within the granites of the geothermal field, bounding at depth the vapor-filled heavily-fractured rock matrix that hosts the shallow steam-dominated geothermal reservoirs. The sharp termination at depth of the anisotropic behavior of granites, coinciding with a 2 km-thick stripe of seismicity and diffuse fracturing, points out the sudden change in compressibility of the fluid filling the fractures and is a key-evidence of deep fluids that locally traversed the supercritical conditions. The presence of SCF and fracture permeability in nominally ductile granitic rocks open new scenarios for the understanding of magmatic systems and for geothermal exploitation.
Geothermal hydrology of Valles Caldera and the southwestern Jemez Mountains, New Mexico

USGS Publications Warehouse

Trainer, Frank W.; Rogers, Robert J.; Sorey, M.L.

2000-01-01

The Jemez Mountains in north-central New Mexico are volcanic in origin and have a large central caldera known as Valles Caldera. The mountains contain the Valles geothermal system, which was investigated during 1970-82 as a source of geothermal energy. This report describes the geothermal hydrology of the Jemez Mountains and presents results of an earlier 1972-75 U.S. Geological Survey study of the area in light of more recent information. Several distinct types of thermal and nonthermal ground water are recognized in the Jemez Mountains. Two types of near-surface thermal water are in the caldera: thermal meteoric water and acid sulfate water. The principal reservoir of geothermal fluids is at depth under the central and western parts of the caldera. Nonthermal ground water in Valles Caldera occurs in diverse perched aquifers and deeper valley-fill aquifers. The geothermal reservoir is recharged by meteorically derived water that moves downward from the aquifers in the caldera fill to depths of 6,500 feet or more and at temperatures reaching about 330 degrees Celsius. The heated geothermal water rises convectively to depths of 2,000 feet or less and mixes with other ground water as it flows away from the geothermal reservoir. A vapor zone containing steam, carbon dioxide, and other gases exists above parts of the liquid-dominated geothermal zone. Two subsystems are generally recognized within the larger geothermal system: the Redondo Creek subsystem and the Sulphur Creek subsystem. The permeability in the Redondo Creek subsystem is controlled by stratigraphy and fault-related structures. Most of the permeability is in the high-angle, normal faults and associated fractures that form the Redondo Creek Graben. Faults and related fractures control the flow of thermal fluids in the subsystem, which is bounded by high-angle faults. The Redondo Creek subsystem has been more extensively studied than other parts of the system. The Sulphur Springs subsystem is not as well defined. The upper vapor-dominated zone in the Sulphur Creek subsystem is separated from the liquid-dominated zone by about 800 feet of sealed caldera-fill rock. Acid springs occur at the top of the vapor zone in the Sulphur Springs area. Some more highly permeable zones within the geothermal reservoir are interconnected, but the lack of interference effects among some wells during production tests suggests effective hydraulic separation along some subsystem boundaries. Chemical and thermal evidence suggests that the Sulphur Springs subsystem may be isolated from the Redondo Creek subsystem and each may have its own zone of upflow and lateral outflow. The area of the entire geothermal reservoir is estimated to be about 12 to 15 square miles; its western limit generally is thought to be at the ring-fracture zone of the caldera. The top of the reservoir is generally considered to be the bottom of a small- permeability 'caprock' that is about 2,000 to 3,000 feet below land surface. Estimated thicknesses to the bottom of the reservoir range from 2,000 to 6,000 feet. Reservoir temperatures measured in exploration wells range from 225 degrees Celsius just below the caprock to about 330 degrees Celsius in deeper drill holes. Pressures measured in exploration wells in the Redondo Creek area ranged from 450 to 1,850 pounds per square inch. Steam-producing zones have been encountered above the liquid- dominated zones in wells, but the extent of steam zones is not well defined. The reservoir contains a near-neutral, chloride-type water containing about 7,000 milligrams per liter dissolved solids. No thermal springs in the caldera have geochemical characteristics similar to those of the geothermal reservoir fluids sampled in wells. Oxygen-18 and deuterium isotope concentrations of geothermal reservoir fluid indicate a meteoric origin. The moat valleys in
The Effect of Boiling on Seismic Properties of Water-Saturated Fractured Rock

NASA Astrophysics Data System (ADS)

Grab, Melchior; Quintal, Beatriz; Caspari, Eva; Deuber, Claudia; Maurer, Hansruedi; Greenhalgh, Stewart

2017-11-01

Seismic campaigns for exploring geothermal systems aim at detecting permeable formations in the subsurface and evaluating the energy state of the pore fluids. High-enthalpy geothermal resources are known to contain fluids ranging from liquid water up to liquid-vapor mixtures in regions where boiling occurs and, ultimately, to vapor-dominated fluids, for instance, if hot parts of the reservoir get depressurized during production. In this study, we implement the properties of single- and two-phase fluids into a numerical poroelastic model to compute frequency-dependent seismic velocities and attenuation factors of a fractured rock as a function of fluid state. Fluid properties are computed while considering that thermodynamic interaction between the fluid phases takes place. This leads to frequency-dependent fluid properties and fluid internal attenuation. As shown in a first example, if the fluid contains very small amounts of vapor, fluid internal attenuation is of similar magnitude as attenuation in fractured rock due to other mechanisms. In a second example, seismic properties of a fractured geothermal reservoir with spatially varying fluid properties are calculated. Using the resulting seismic properties as an input model, the seismic response of the reservoir is then computed while the hydrothermal structure is assumed to vary over time. The resulting seismograms demonstrate that anomalies in the seismic response due to fluid state variability are small compared to variations caused by geological background heterogeneity. However, the hydrothermal structure in the reservoir can be delineated from amplitude anomalies when the variations due to geology can be ruled out such as in time-lapse experiments.
From source to surface: Tracking magmatic boron and chlorine input into the geothermal systems of the Taupo Volcanic Zone, New Zealand

NASA Astrophysics Data System (ADS)

Bégué, Florence; Deering, Chad D.; Gravley, Darren M.; Chambefort, Isabelle; Kennedy, Ben M.

2017-10-01

The magmatic contribution into geothermal fluids in the central Taupo Volcanic Zone (TVZ), New Zealand, has been attributed to either andesitic, 'arc-type' fluids, or rhyolitic, 'rift-type' fluids to explain the compositional diversity of discharge waters. However, this model relies on outdated assumptions related to geochemical trends associated with the magma at depth of typical arc to back-arc settings. Current tectonic models have shown that the TVZ is situated within a rifting arc and hosts magmatic systems dominated by distinct rhyolite types, that are likely to have evolved under different conditions than the subordinate andesites. Therefore, a new appraisal of the existing models is required to further understand the origin of the spatial compositional diversity observed in the geothermal fluids and its relationship to the structural setting. Here, we use volatile concentrations (i.e. H2O, Cl, B) from rhyolitic and andesitic mineral-hosted melt inclusions to evaluate the magmatic contribution to the TVZ geothermal systems. The andesite and two different types of rhyolites (R1 and R2) are each distinct in Cl/H2O and B/Cl, which will affect volatile solubility and phase separation (vapor vs. hydrosaline liquid) of the exsolved volatile phase. Ultimately, these key differences in the magmatic volatile constituents will play a significant role in governing the concentration of Cl discharged into geothermal systems. We estimate bulk fluid compositions (B and Cl) in equilibrium with the different melt types to show the potential contribution of 'parent' fluids to the geothermal systems throughout the TVZ. The results of this analysis show that the variability in fluid compositions partly reflects degassing from previously unaccounted for distinct magma source compositions. We suggest the geothermal systems that appear to have an 'arc-type' andesitic fluid contribution are actually derived from a rhyolite melt in equilibrium with a highly crystalline andesite magma. This model is in better agreement with the current understanding of magma petrogenesis in the central TVZ and its atypical rifted-arc tectonic setting, and show that the central TVZ records an arc, not back-arc, fluid signature.

Laboratory investigations of the physics of steam flow in a porous medium

USGS Publications Warehouse

Herkelrath, W.N.; Moench, A.F.

1982-01-01

Experiments were carried out in the laboratory to test a theory of transient flow of pure steam in a uniform porous medium. This theory is used extensively in modeling pressure-transient behavior in vapor-dominated geothermal systems. Transient, superheated steam-flow experiments were run by bringing a cylinder of porous material to a uniform initial pressure, and then making a step increase in pressure at one end of the sample, while monitoring the pressure-transient breakthrough at the other end. It was found in experiments run at 100?, 125?, and 146?C that the time required for steam-pressure transients to propagate through an unconsolidated material containing sand, silt, and clay was 10 to 25 times longer than predicted by theory. It is hypothesized that the delay in the steam-pressure transient was caused by adsorption of steam in the porous sample. In order to account for steam adsorption, a sink term was included in the conservation of mass equation. In addition, energy transfer in the system has to be considered because latent heat is released when steam adsorption occurs, increasing the sample temperature by as much as 10?C. Finally, it was recognized that the steam pressure was a function of both the temperature and the amount of adsorption in the sample. For simplicity, this function was assumed to be in equilibrium adsorption isotherm, which was determined by experiment. By solving the modified mass and energy equations numerically, subject to the empirical adsorption isotherm relationship, excellent theoretical simulation of the experiments was achieved. The experiments support the hypothesis that adsorption of steam can strongly influence steam pressure-transient behavior in porous media; the results suggest that the modified steam-flow theory, which includes steam adsorption terms, should be used in modeling steam flow in vapor-dominated geothermal systems.
Gas chemistry of Icelandic thermal fluids

NASA Astrophysics Data System (ADS)

Stefánsson, Andri

2017-10-01

The chemistry of gases in thermal fluids from Iceland was studied in order to evaluate the sources and processes affecting volatile concentrations in volcanic geothermal systems at divergent plate boundaries. The fluids included vapor fumaroles and two-phase well discharges with temperatures of 100-340 °C. The vapor was dominated by H2O accounting for 62-100 mol% and generally for > 99 mol%, with CO2, H2S and H2 being the dominant gases followed by N2, CH4, and Ar. Overall mineral-gas and gas-gas equilibria were not observed for the major gases, including CO2, H2S, H2 and CH4 within the geothermal reservoirs. Instead the system proved to be controlled by source(s) and their ratios and various metastable equilibria along a fluid-rock reaction progress with gas concentrations controlled by such metastable equilibria varying at particular temperatures as a functional extent of reaction. The concentrations of H2S and H2 closely reflect mineral-fluid metastable equilibria, whereas CO2 concentrations are controlled by the input of magma gas corresponding to > 0.1 to < 5% mass input. With fluid ascent to the surface, boiling and condensation may occur, further changing the gas concentrations and hence surface fumaroles may not reflect the reservoir fluid characteristics but rather secondary processes.
Vapor-dominated zones within hydrothermal systems: evolution and natural state

USGS Publications Warehouse

Ingebritsen, S.E.; Sorey, M.L.

1988-01-01

Three conceptual models illustrate the range of hydrothermal systems in which vapor-dominated conditions are found. The first model (model I) represents a system with an extensive near-vaporstatic vapor-dominated zone and limited liquid throughflow and is analogous to systems such as The Geysers, California. Models II and III represent systems with significant liquid throughflow and include steam-heated discharge features at higher elevations and high-chloride springs at lower elevations connected to and fed by a single circulation system at depth. In model II, as in model I, the vapor-dominated zone has a near-vaporstatic vertical pressure gradient and is generally underpressured with respect to local hydrostatic pressure. The vapor-dominated zone in model III is quite different, in that phase separation takes place at pressures close to local hydrostatic and the overall pressure gradient is near hydrostatic. -from Authors
Recent exploration and development of geothermal energy resources in the Escalante desert region, Southwestern Utah

USGS Publications Warehouse

Blackett, Robert E.; Ross, Howard P.

1994-01-01

Development of geothermal resources in southwest Utah's Sevier thermal area continued in the early 1990s with expansion of existing power-generation facilities. Completion of the Bud L. Bonnett geothermal power plant at the Cove Fort-Sulphurdale geothermal area brought total power generation capacity of the facility to 13.5 MWe (gross). At Cove Fort-Sulphurdate, recent declines in steam pressures within the shallow, vapor-dominated part of the resource prompted field developers to complete additional geothermal supply wells into the deeper, liquid-dominated portion of the resource. At Roosevelt Hot Springs near Milford, Intermountain Geothermal Company completed an additional supply well for Utah Power and Light Company's single-flash, Blundell plant. with the increased geothermal fluid supply from the new well, the Blundell plant now produces about 26 MWe (gross). The authors conducted several geothermal resource studies in undeveloped thermal areas in southwest Utah. Previous studies at Newcastle revealed a well-defined, self-potential minimum coincident with the intersection of major faults and the center of the heatflow anomaly. A detailed self-potential survey at Wood's Ranch, an area in northwest Iron County where thermal water was encountered in shallow wells, revealed a large (5,900 ?? 2,950 feet [1,800 ?? 900 m]) northeast-oriented self-potential anomaly which possibly results from the flow of shallow thermal fluid. Chemical geothermometry applied to Wood's Ranch water samples suggest reservoir temperatures between 230 and 248??F (110 and 120??C). At the Thermo Hot Springs geothermal area near Minersville, detailed self-potential surveys have also revealed an interesting 100 mV negative anomaly possibly related to the upward flow of hydrothermal fluid.
High-temperature explosive development for geothermal well stimulation. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schmidt, E.W.; Mars, J.E.; Wang, C.

1978-03-31

A two-component, temperature-resistant liquid explosive called HITEX has been developed which is capable of withstanding 561/sup 0/K (550/sup 0/F) for 24 hours in a geothermal environment. The explosive is intended for the stimulation of nonproducing or marginally producing geothermal (hot dry rock, vapor-dominated or hydrothermal) reservoirs by fracturing the strata in the vicinity of a borehole. The explosive is inherently safe because it is mixed below ground downhole from two nondetonable liquid components. Development and safety tests included differential scanning calorimetry, thermal stability, minerals compatibility, drop-weight sensitivity, adiabatic compression, electrostatic discharge sensitivity, friction sensitivity, detonation arrest capability, cook-off tests, detonabilitymore » at ambient and elevated pressure, detonation velocity and thin film propagation in a wedge.« less
Reservoir controling factors in the Karaha-Telaga Bodas geothermal field, Indonesia

USGS Publications Warehouse

Nemcok, M.; Moore, J.N.; Christensen, Carl; Allis, R.; Powell, T.; Murray, B.; Nash, G.

2005-01-01

Karaha - Telaga Bodas geothermal system consists of: 1) a caprock, ranging from several hundred meters to 1600 m thick that is characterized by steep, conductive temperature gradients and low permeabilities; 2) an underlying vapor-dominated zone that extends below sea level; and 3) a deep liquid-dominated zone with measured temperatures up to 353??C. Heat is provided by a 3 km deep tabular granodiorite stock. The effective base of the reservoir is controlled by the stress regime's effect on fractures within volcanic rocks located above the brittle/ductile deformation boundary. The base of the caprock is controlled by the distribution of initially low-permeability lithologies above the reservoir; the extent of pervasive clay alteration that has reduced initial permeabilities; the distribution of secondary minerals deposited by descending waters; and by a downward change from a strike-slip to an extensional stress regime. Producing zones are controlled by both matrix and fracture permeabilities.
Hybrid Geothermal Heat Pumps for Cooling Telecommunications Data Centers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beckers, Koenraad J; Zurmuhl, David P.; Lukawski, Maciej Z.

The technical and economic performance of geothermal heat pump (GHP) systems supplying year-round cooling to representative small data centers with cooling loads less than 500 kWth were analyzed and compared to air-source heat pumps (ASHPs). A numerical model was developed in TRNSYS software to simulate the operation of air-source and geothermal heat pumps with and without supplementary air cooled heat exchangers - dry coolers (DCs). The model was validated using data measured at an experimental geothermal system installed in Ithaca, NY, USA. The coefficient of performance (COP) and cooling capacity of the GHPs were calculated over a 20-year lifetime andmore » compared to the performance of ASHPs. The total cost of ownership (TCO) of each of the cooling systems was calculated to assess its economic performance. Both the length of the geothermal borehole heat exchangers (BHEs) and the dry cooler temperature set point were optimized to minimize the TCO of the geothermal systems. Lastly, a preliminary analysis of the performance of geothermal heat pumps for cooling dominated systems was performed for other locations including Dallas, TX, Sacramento, CA, and Minneapolis, MN.« less
Numerical simulation of water injection into vapor-dominated reservoirs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pruess, K.

1995-01-01

Water injection into vapor-dominated reservoirs is a means of condensate disposal, as well as a reservoir management tool for enhancing energy recovery and reservoir life. We review different approaches to modeling the complex fluid and heat flow processes during injection into vapor-dominated systems. Vapor pressure lowering, grid orientation effects, and physical dispersion of injection plumes from reservoir heterogeneity are important considerations for a realistic modeling of injection effects. An example of detailed three-dimensional modeling of injection experiments at The Geysers is given.
DOE Office of Scientific and Technical Information (OSTI.GOV)

T. H. Brikowski; D. L. Norton; D. D. Blackwell

Final project report of natural state modeling effort for The Geysers geothermal field, California. Initial models examined the liquid-dominated state of the system, based on geologic constraints and calibrated to match observed whole rock delta-O18 isotope alteration. These models demonstrated that the early system was of generally low permeability (around 10{sup -12} m{sup 2}), with good hydraulic connectivity at depth (along the intrusive contact) and an intact caprock. Later effort in the project was directed at development of a two-phase, supercritical flow simulation package (EOS1sc) to accompany the Tough2 flow simulator. Geysers models made using this package show that ''simmering'',more » or the transient migration of vapor bubbles through the hydrothermal system, is the dominant transition state as the system progresses to vapor-dominated. Such a system is highly variable in space and time, making the rock record more difficult to interpret, since pressure-temperature indicators likely reflect only local, short duration conditions.« less
Beneficial effects of groundwater entry into liquid-dominated geothermal systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lippmann, M.J.; Truesdell, A.H.

In all active liquid-dominated geothermal systems there is continuous circulation of mass and transfer of heat, otherwise they would slowly cool and fade away. In the natural state these systems are in dynamic equilibrium with the surrounding colder groundwater aquifers. The ascending geothermal fluids cool conductively, boil, or mix with groundwaters, and ultimately may discharge at the surface as fumaroles or hot springs. With the start of fluid production and the lowering of reservoir pressure, the natural equilibrium is disrupted and cooler groundwater tends to enter the reservoir. Improperly constructed or damaged wells, and wells located near the margins ofmore » the geothermal system, exhibit temperature reductions (and possibly scaling from mixing of chemically distinct fluids) as the cooler-water moves into the reservoir. These negative effects, especially in peripheral wells are, however, compensated by the maintenance of reservoir pressure and a reduction in reservoir boiling that might result in mineral precipitation in the formation pores and fractures. The positive effect of cold groundwater entry on the behavior of liquid-dominated system is illustrated by using simple reservoir models. The simulation results show that even though groundwater influx into the reservoir causes cooling of fluids produced from wells located near the cold-water recharge area, it also reduces pressure drawdown and boiling in the exploited zone, and sweeps the heat stored in the reservoir rocks toward production wells, thus increasing the productive life of the wells and field. 9 refs.« less
Synthetic Modeling of A Geothermal System Using Audio-magnetotelluric (AMT) and Magnetotelluric (MT)

NASA Astrophysics Data System (ADS)

Mega Saputra, Rifki; Widodo

2017-04-01

Indonesia has 40% of the world’s potential geothermal resources with estimated capacity of 28,910 MW. Generally, the characteristic of the geothermal system in Indonesia is liquid-dominated systems, which driven by volcanic activities. In geothermal exploration, electromagnetic methods are used to map structures that could host potential reservoirs and source rocks. We want to know the responses of a geothermal system using synthetic data of Audio-magnetotelluric (AMT) and Magnetotelluric (MT). Due to frequency range, AMT and MT data can resolve the shallow and deeper structure, respectively. 1-D models have been performed using AMT and MT data. The results indicate that AMT and MT data give detailed conductivity distribution of geothermal structure.
Microbes in mercury-enriched geothermal springs in western North America.

PubMed

Geesey, Gill G; Barkay, Tamar; King, Sue

2016-11-01

Because geothermal environments contain mercury (Hg) from natural sources, microorganisms that evolved in these systems have likely adapted to this element. Knowledge of the interactions between microorganisms and Hg in geothermal systems may assist in understanding the long-term evolution of microbial adaptation to Hg with relevance to other environments where Hg is introduced from anthropogenic sources. A number of microbiological studies with supporting geochemistry have been conducted in geothermal systems across western North America. Approximately 1 in 5 study sites include measurements of Hg. Of all prokaryotic taxa reported across sites with microbiological and accompanying physicochemical data, 42% have been detected at sites in which Hg was measured. Genes specifying Hg reduction and detoxification by microorganisms were detected in a number of hot springs across the region. Archaeal-like sequences, representing two crenarchaeal orders and one order each of the Euryarchaeota and Thaumarchaeota, dominated in metagenomes' MerA (the mercuric reductase protein) inventories, while bacterial homologs were mostly found in one deeply sequenced metagenome. MerA homologs were more frequently found in metagenomes of microbial communities in acidic springs than in circumneutral or high pH geothermal systems, possibly reflecting higher bioavailability of Hg under acidic conditions. MerA homologs were found in hot springs prokaryotic isolates affiliated with Bacteria and Archaea taxa. Acidic sites with high Hg concentrations contain more of Archaea than Bacteria taxa, while the reverse appears to be the case in circumneutral and high pH sites with high Hg concentrations. However, MerA was detected in only a small fraction of the Archaea and Bacteria taxa inhabiting sites containing Hg. Nevertheless, the presence of MerA homologs and their distribution patterns in systems, in which Hg has yet to be measured, demonstrates the potential for detoxification by Hg reduction in these geothermal systems, particularly the low pH springs that are dominated by Archaea. Copyright © 2016 Elsevier B.V. All rights reserved.
Phase relations and adiabats in boiling seafloor geothermal systems

USGS Publications Warehouse

Bischoff, J.L.; Pitzer, Kenneth S.

1985-01-01

Observations of large salinity variations and vent temperatures in the range of 380-400??C suggest that boiling or two-phase separation may be occurring in some seafloor geothermal systems. Consideration of flow rates and the relatively small differences in density between vapors and liquids at the supercritical pressures at depth in these systems suggests that boiling is occurring under closed-system conditions. Salinity and temperature of boiling vents can be used to estimate the pressure-temperature point in the subsurface at which liquid seawater first reached the two-phase boundary. Data are reviewed to construct phase diagrams of coexisting brines and vapors in the two-phase region at pressures corresponding to those of the seafloor geothermal systems. A method is developed for calculating the enthalpy and entropy of the coexisting mixtures, and results are used to construct adiabats from the seafloor to the P-T two-phase boundary. Results for seafloor vents discharging at 2300 m below sea level indicate that a 385??C vent is composed of a brine (7% NaCl equivalent) in equilibrium with a vapor (0.1% NaCl). Brine constitutes 45% by weight of the mixture, and the fluid first boiled at approximately 1 km below the seafloor at 415??C, 330 bar. A 400??C vent is primarily vapor (88 wt.%, 0.044% NaCl) with a small amount of brine (26% NaCl) and first boiled at 2.9 km below the seafloor at 500??C, 520 bar. These results show that adiabatic decompression in the two-phase region results in dramatic cooling of the fluid mixture when there is a large fraction of vapor. ?? 1985.
Structural controls on fluid circulation at the Caviahue-Copahue Volcanic Complex (CCVC) geothermal area (Chile-Argentina), revealed by soil CO2 and temperature, self-potential, and helium isotopes

NASA Astrophysics Data System (ADS)

Roulleau, Emilie; Bravo, Francisco; Pinti, Daniele L.; Barde-Cabusson, Stéphanie; Pizarro, Marcela; Tardani, Daniele; Muñoz, Carlos; Sanchez, Juan; Sano, Yuji; Takahata, Naoto; de la Cal, Federico; Esteban, Carlos; Morata, Diego

2017-07-01

Natural geothermal systems are limited areas characterized by anomalously high heat flow caused by recent tectonic or magmatic activity. The heat source at depth is the result of the emplacement of magma bodies, controlled by the regional volcano-tectonic setting. In contrast, at a local scale a well-developed fault-fracture network favors the development of hydrothermal cells, and promotes the vertical advection of fluids and heat. The Southern Volcanic Zone (SVZ), straddling Chile and Argentina, has an important, yet unexplored and undeveloped geothermal potential. Studies on the lithological and tectonic controls of the hydrothermal circulation are therefore important for a correct assessment of the geothermal potential of the region. Here, new and dense self-potential (SP), soil CO2 and temperature (T) measurements, and helium isotope data measured in fumaroles and thermal springs from the geothermal area located in the north-eastern flank of the Copahue volcanic edifice, within the Caviahue Caldera (the Caviahue-Copahue Volcanic Complex - CCVC) are presented. Our results allowed to the constraint of the structural origin of the active thermal areas and the understanding of the evolution of the geothermal system. NE-striking faults in the area, characterized by a combination of SP, CO2, and T maxima and high 3He/4He ratios (up to 8.16 ± 0.21Ra, whereas atmospheric Ra is 1.382 × 10- 6), promote the formation of vertical permeability preferential pathways for fluid circulation. WNW-striking faults represent low-permeability pathways for hydrothermal fluid ascent, but promote infiltration of meteoric water at shallow depths, which dilute the hydrothermal input. The region is scattered with SP, CO2, and T minima, representing self-sealed zones characterized by impermeable altered rocks at depth, which create local barriers for fluid ascent. The NE-striking faults seem to be associated with the upflowing zones of the geothermal system, where the boiling process produces a high vapor-dominated zone close to the surface, whereas the WNW-striking faults could act as a boundary of the Copahue geothermal area to the south.
Fluid inclusions in minerals from the geothermal fields of Tuscany, Italy

USGS Publications Warehouse

Belkin, H.; de Vivo, B.; Gianelli, G.; Lattanzi, P.

1985-01-01

A reconnaissance study on fluid inclusions from the geothermal fields of Tuscany indicates that the hydrothermal minerals were formed by fluids which were, at least in part, boiling. Four types of aqueous inclusions were recognized: (A) two-phase (liquid + vapor) liquid rich, (B) two-phase (vapor + liquid) vapor rich, (C) polyphase hypersaline liquid rich and (D) three phase-H2O liquid + CO2 liquid + CO2-rich vapor. Freezing and heating microthermometric determinations are reported for 230 inclusions from samples from six wells. It is suggested that boiling of an originally homogeneous, moderately saline, CO2-bearing liquid phase produced a residual hypersaline brine and a CO2-rich vapor phase. There are indications of a temperature decrease in the geothermal field of Larderello, especially in its peripheral zones. ?? 1985.
The geothermal system of Caviahue-Copahue Volcanic Complex (Chile-Argentina): New insights from self-potential, soil CO2 degassing, temperature measurements and helium isotopes, with structural and fluid circulation implications.

NASA Astrophysics Data System (ADS)

Roulleau, Emilie; Bravo, Francisco; Barde-Cabusson, Stephanie; Pizarro, Marcela; Muños, Carlos; Sanchez, Juan; Tardani, Daniele; Sano, Yuji; Takahata, Naoto; de Cal, Federico; Esteban, Carlos

2016-04-01

Geothermal systems represent natural heat transfer engines in a confined volume of rock which are strongly influenced by the regional volcano-tectonic setting controlling the formation of shallow magmatic reservoirs, and by the local faults/fracture network, that permits the development of hydrothermal circulation cells and promote the vertical migration of fluids and heat. In the Southern Volcanic Zone of Chile-Argentina, geothermal resources occur in close spatial relationship with active volcanism along the Cordillera which is primarily controlled by the 1000 km long, NNE Liquiñe-Ofqui Fault Zone (LOFZ), an intra-arc dextral strike-slip fault system, associated with second-order intra-arc anisotropy of overall NE-SW (extensional) and NW-SE orientation (compressional). However there is still a lack of information on how fault network (NE and WNW strinking faults) and lithology control the fluid circulation. In this study, we propose new data of dense self-potential (SP), soil CO2 emanation and temperature (T) measurements within the geothermal area from Caviahue-Copahue Volcanic Complex (CCVC), coupled with helium isotopes ratios measured in fumaroles and thermal springs. We observe that inside the geothermal system the NE-striking faults, characterized by a combination of SP-CO2 and T maxima with high 3He/4He ratios (7.86Ra), promote the formation of high vertical permeability pathways for fluid circulation. Whereas, the WNW-striking faults represent low permeability pathways for hydrothermal fluids ascent associated with moderate 3He/4He ratios (5.34Ra), promoting the infiltration of meteoric water at shallow depth. These active zones are interspersed by SP-CO2- T minima, which represent self-sealed zones (e.g. impermeable altered rocks) at depth, creating a barrier inhibiting fluids rise. The NE-striking faults seem to be associated with the upflow zones of the geothermal system, where the boiling process produces a high vapor-dominated zone close to the surface. The WNW-striking faults seems to limit to the south the Copahue geothermal area.
Self-organizing maps in geothermal exploration-A new approach for understanding geochemical processes and fluid evolution

NASA Astrophysics Data System (ADS)

Brehme, Maren; Bauer, Klaus; Nukman, Mochamad; Regenspurg, Simona

2017-04-01

Understanding geochemical processes is an important part of geothermal exploration to get information about the source and evolution of geothermal fluids. However, in most cases knowledge of fluid properties is based on few parameters determined in samples from the shallow subsurface. This study presents a new approach that allows to conclude from the combination of a variety of these data on processes occurring at depth in a geothermal reservoir. The neural network clustering technique called "self-organizing maps" (SOMs) successfully distinguished two different geothermal settings based on a hydrochemical database and disclosed the source, evolution and flow pathways of geothermal fluids. Scatter plots, as shown in this study, are appropriate presentations of element concentrations and the chemical interaction of water and rock at depth. One geological setting presented here is marked by fault dominated fluid pathways and minor influence of volcanic affected fluids with high concentrations of HCO3, Ca and Sr. The second is a magmatically dominated setting showing strong alteration features in volcanic rocks and accommodates acidic fluids with high SO4 and Si concentrations. Former studies, i.e., Giggenbach (1988), suggested Cl, HCO3 and SO4 to be generally the most important elements for understanding hydrochemical processes in geothermal reservoirs. Their relation has been widely used to classify different water types in geothermal fields. However, this study showed that non-standard elements are at least of same importance to reveal different fluid types in geothermal systems. Therefore, this study is an extended water classification approach using SOM for element correlations. SOM have been proven to be a successful method for analyzing even relatively small hydrochemical datasets in geothermal applications.
Hydrochemical-isotopic and hydrogeological conceptual model of the Las Tres Vírgenes geothermal field, Baja California Sur, México

NASA Astrophysics Data System (ADS)

Portugal, E.; Birkle, P.; Barragán R, R. M.; Arellano G, V. M.; Tello, E.; Tello, M.

2000-09-01

Based on geological, structural, hydrochemical and isotopic data, a hydrogeological conceptual model for the geothermal reservoir, shallow wells and springs at the Las Tres Vírgenes geothermal field and its surroundings is proposed. The model explains the genesis of different types of thermal and cold groundwater in the NW (El Azufre Valley, Las Tres Vírgenes and Aguajito complex), NE (Reforma complex) and S (Sierra Mezquital) areas. Shallow groundwater of sulfate type in the NW zone is explained by the rise of CO2-H2S vapor from a shallow magma chamber and the subsequent heating up of a shallow aquifer. Vertical communication between the reservoir and the surface is facilitated by a series of extensional, NW-SE-trending normal faults, forming the graben structures of the Santa Rosalía Basin. Low-permeability characteristics of the geological formations of the study area support the hypothesis of a fracture and fault-dominated, subterranean-flow circulation system. The Na- (Cl-HCO3) composition of springs in the NE and SE zones indicates influence of ascending geothermal fluids, facilitated by radial fault systems of the Reforma caldera and probably the existence of a shallow magma chamber. Close to the surface, the rising geothermal fluids are mixed up with meteoric water from a shallow aquifer. The Las Tres Vírgenes and the Reforma complex are separated by younger, N-S-trending lateral shearing faults, such as the Cimarrón fault; such disposition explains the genesis of different hydrogeological flow regimes on both sides. HCO3-type surface water from the southern zone between San Ignacio and Mezquital is of typical meteoric origin, with no influence of geothermal fluids. Due to arid climatic conditions in the study zone, recent recharge in the geothermal area seems improbable; thus, recent interaction between the surface and the geothermal reservoir can be excluded. Furthermore, isotopic and hydrochemical data exclude the presence of marine water from the Gulf of California in the deep reservoir. Both conditions indicate recharge of the reservoir by meteoric water during glacial periods in Holocene or Pleistocene time, or a magmatic origin of the reservoir fluids. The slightly positive slope of the δ18O-δD line of geothermal fluids and its intermediate isotopic composition-between the surface samples and magmatic (;andesitic;) water indicate that magmatic (;andesitic;) water contributes approximately 30% to the geothermal fluid composition, whereas ;fossil; meteoric water represents the major component (70%). The geothermal reservoir is considered to represent a hydrostatic, stagnant flow system. Based on the observed linear correlation between the isotopic composition and the altitude of the surface manifestations, the isotopic composition and altitude of the former recharge were determined as δ18O=-9.7‰ and δD=-67.3‰, and 350 m.a.s.l., respectively. This altitude is interpreted as mean (average) recharge elevation. Scarcity of permanent rivers, low density of springs and domestic wells, as well as low precipitation rates, reflect restricted distribution of shallow groundwater systems in the study zone. These systems are related to isolated, local aquifers composed of valley fillings.
Geological and geophysical analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galbraith, R.M.

1978-05-01

The Coso Geothermal Exploration Hole number one (CGEH-1) was drilled in the Coso Hot Springs KGRA, California, from September 2 to December 2, 1977. Chip samples were collected at ten foot intervals and extensive geophysical logging surveys were conducted to document the geologic character of the geothermal system as penetrated by CGEH-1. The major rock units encountered include a mafic metamorphic sequence and a leucogranite which intruded the metamorphic rocks. Only weak hydrothermal alteration was noted in these rocks. Drillhole surveys and drilling rate data indicate that the geothermal system is structurally controlled and that the drillhole itself was stronglymore » influenced by structural zones. Water chemistry indicates that this geothermal resource is a hot-water rather than a vapor-dominated system. Several geophysical logs were employed to characcterize the drillhole geology. The natural gamma and neutron porosity logs indicate gross rock type and the accoustic logs indicate fractured rock and potentially permeable zones. A series of temperature logs run as a function of time during and after the completion of drilling were most useful in delineating the zones of maximum heat flux. Convective heat flow and temperatures greater than 350/sup 0/F appear to occur only along an open fracture system encountered between depths of 1850 and 2775 feet. Temperature logs indicate a negative thermal gradient below 3000 feet.« less
Geological and geophysical analysis of Coso Geothermal Exploration Hole No. 1 (CGEH-1), Coso Hot Springs KGRA, California

DOE Office of Scientific and Technical Information (OSTI.GOV)

Galbraith, R.M.

1978-05-01

The Coso Geothermal Exploration Hole number one (CGEH-1) was drilled in the Coso Hot Springs KGRA, California from September 2 to December 2, 1977. Chip samples were collected at ten foot intervals and extensive geophysical logging surveys were conducted to document the geologic character of the geothermal system as penetrated by CGEH-1. The major rock units encountered include a mafic metamorphic sequence and a leucogranite which intruded the metamorphic rocks. Only weak hydrothermal alteration was noted in these rocks. Drillhole surveys and drilling rate data indicate that the geothermal system is structurally controlled and that the drillhole itself was stronglymore » influenced by structural zones. Water chemistry indicates that this geothermal resource is a hot-water rather than a vapor-dominated system. Several geophysical logs were employed to characterize the drillhole geology. The natural gamma and neutron porosity logs indicate gross rock type and the acoustic logs indicate fractured rock and potentially permeable zones. A series of temperature logs run as a function of time during and after the completion of drilling were most useful in delineating the zones of maximum heat flux. Convective heat flow and temperatures greater than 350/sup 0/F appear to occur only along an open fracture system encountered between depths of 1850 and 2775 feet. Temperature logs indicate a negative thermal gradient below 3000 feet.« less

Magmatic-vapor expansion and the formation of high-sulfidation gold deposits: Chemical controls on alteration and mineralization

USGS Publications Warehouse

Henley, R.W.; Berger, B.R.

2011-01-01

Large bulk-tonnage high-sulfidation gold deposits, such as Yanacocha, Peru, are the surface expression of structurally-controlled lode gold deposits, such as El Indio, Chile. Both formed in active andesite-dacite volcanic terranes. Fluid inclusion, stable isotope and geologic data show that lode deposits formed within 1500. m of the paleo-surface as a consequence of the expansion of low-salinity, low-density magmatic vapor with very limited, if any, groundwater mixing. They are characterized by an initial 'Sulfate' Stage of advanced argillic wallrock alteration ?? alunite commonly with intense silicification followed by a 'Sulfide' Stage - a succession of discrete sulfide-sulfosalt veins that may be ore grade in gold and silver. Fluid inclusions in quartz formed during wallrock alteration have homogenization temperatures between 100 and over 500 ??C and preserve a record of a vapor-rich environment. Recent data for El Indio and similar deposits show that at the commencement of the Sulfide Stage, 'condensation' of Cu-As-S sulfosalt melts with trace concentrations of Sb, Te, Bi, Ag and Au occurred at > 600 ??C following pyrite deposition. Euhedral quartz crystals were simultaneously deposited from the vapor phase during crystallization of the vapor-saturated melt occurs to Fe-tennantite with progressive non-equilibrium fractionation of heavy metals between melt-vapor and solid. Vugs containing a range of sulfides, sulfosalts and gold record the changing composition of the vapor. Published fluid inclusion and mineralogical data are reviewed in the context of geological relationships to establish boundary conditions through which to trace the expansion of magmatic vapor from source to surface and consequent alteration and mineralization. Initially heat loss from the vapor is high resulting in the formation of acid condensate permeating through the wallrock. This Sulfate Stage alteration effectively isolates the expansion of magmatic vapor in subsurface fracture arrays from any external contemporary hydrothermal activity. Subsequent fracturing is localized by the embrittled wallrock to provide high-permeability fracture arrays that constrain vapor expansion with minimization of heat loss. The Sulfide Stage vein sequence is then a consequence of destabilization of metal-vapor species in response to depressurization and decrease in vapor density. The geology, mineralogy, fluid inclusion and stable isotope data and geothermometry for high-sulfidation, bulk-tonnage and lode deposits are quite different from those for epithermal gold-silver deposits such as McLaughlin, California that formed near-surface in groundwater-dominated hydrothermal systems where magmatic fluid has been diluted to less than about 30%. High sulfidation gold deposits are better termed 'Solfataric Gold Deposits' to emphasize this distinction. The magmatic-vapor expansion hypothesis also applies to the phenomenology of acidic geothermal systems in active volcanic systems and equivalent magmatic-vapor discharges on the flanks of submarine volcanoes. ?? 2010.
Geochemistry of thermal fluids in NW Honduras: New perspectives for exploitation of geothermal areas in the southern Sula graben

NASA Astrophysics Data System (ADS)

Capaccioni, Bruno; Franco, Tassi; Alberto, Renzulli; Orlando, Vaselli; Marco, Menichetti; Salvatore, Inguaggiato

2014-06-01

The results of a geochemical survey on thermal waters and, for the first time for this site, gas discharges in five geothermal sites (Azacualpa "La Cueva", Río Ulua, Río Gualcarque, El Olivar and Laguna de Agua Caliente) in NW Honduras are here presented and discussed. El Olivar and Laguna de Agua Caliente, in the southern part of the Sula graben are very close to a Quaternary basaltic field, whereas Azacualpa "La Cueva", Río Ulua and Río Gualcarque, located to the southwest of the Yojoa Lake, direcly emerge from the Cretaceous limestone deposits. The measured temperatures range between 37.5 and 104.8 °C. "Mature", alkaline, Na-SO4 thermal waters discharge from Azacualpa "La Cueva", while those from El Olivar and Laguna de Agua Caliente are "immature" and show a Na-HCO3 composition. Chemical equilibria of waters and gases from the Azacualpa "La Cueva" thermal springs indicate temperatures ranging from 150 to 200 °C. Conversely, gas discharges from El Olivar and Laguna de Agua Caliente have attained a partial chemical equilibrium in the liquid phase at slightly higher temperatures (200-250 °C), although gas-gas faster reactions involving CO seem to be adjusted in an isothermally separated vapor phase. Unlike Azacualpa, SiO2 geothermometer at El Olivar and Laguna de Agua Caliente indicates equilibrium temperatures for the liquid phase much lower than those calculated for the gas phase (≤ 120 °C). We conclude that thermal waters from the Azacualpa area likely represent the direct emergence of a water dominated reservoir having temperatures ≤ 150-200 °C. By contrast, at El Olivar and Laguna de Agua Caliente hot springs are supplied by a boiling shallow aquifer fed by a vapor phase rising from a steam-dominated zone. The above geochemical model is consistent with a geothermal reservoir hosted within the Cretaceous carbonate sequences of the Yojoa Group in the whole investigated sites. The reservoir extensively crops out in the Azacualpa area whereas the geothermal sites of the southern Sula graben (Laguna de Agua Caliente and El Olivar) are covered by the Oligocene-Miocene volcano-sedimentary sequences of the Matagalpa formation, possibly acting as efficient impermeable cap rocks. These results significantly differ from those reported by previous studies and emphasize that the southern Sula graben, in particular the El Olivar area, can represent among the investigated thermal springs, the most promising site for the exploitation of a high-enthalpy geothermal field.
Analysis of geothermal temperatures for heat pumps application in Paraná (Brasil)

NASA Astrophysics Data System (ADS)

Santos, Alexandre F.; de Souza, Heraldo J. L.; Cantao, Mauricio P.; Gaspar, Pedro D.

2016-11-01

Geothermal heat pumps are broadly used in developed countries but scarcely in Brazil, in part because there is a lack of Brazilian soil temperature data. The aims of this work are: to present soil temperature measurements and to compare geothermal heat pump system performances with conventional air conditioning systems. Geothermal temperature measurement results are shown for ten Paraná State cities, representing different soil and climate conditions. The measurements were made yearlong with calibrated equipment and digital data acquisition system in different measuring stations. Geothermal and ambient temperature data were used for simulations of the coeficient of performance (COP), by means of a working fluid pressure-enthalpy diagram based software for vapor-compression cycle. It was verified that geothermal temperature measured between January 13 to October 13, 2013, varied from 16 to 24 °C, while room temperature has varied between 2 and 35 °C. Average COP values for conventional system were 3.7 (cooling mode) and 5.0 kW/kW (heating mode), corresponding to 5.9 and 7.9 kW/kW for geothermal system. Hence it was verified an average eficiency gain of 59%with geothermal system utilization in comparison with conventional system.
Tectonic Constraints on the Evolution of Geothermal Systems in the Central Andean Volcanic Zone (CAVZ)

NASA Astrophysics Data System (ADS)

Veloso, E. E.; Tardani, D.; Aron, F.; Elizalde, J. D.; Sanchez-Alfaro, P.; Godoy, B.

2017-12-01

South of 19°S, geothermal fields and Pliocene-to-Holocene volcanic centers of the Central Andean Volcanic Zone are spatially associated with distinct, large-scale fault systems disrupting the volcanic arc, which control the architecture and dynamics of the fluids reservoirs at shallow crustal levels. Based on an extensive compilation of structural, lithological and isotopic data, and satellite imagery band-ratio analyses, we produced detailed maps of 13 areas comprising 19 identified and/or potential geothermal fields, to examine if particular local-scale tectonic configurations are associated to fluids migrating from different crustal levels. We defined three main tectonic environments according to the specific, kilometer-scale structural arrangement and its spatial relation to the geothermal surface manifestations. T1, dominated by left-lateral, pure strike-slip motion on a NW-trending duplex-like geometry with geothermal fields located along the faults - in turn distributed into five major subparallel zones cutting across the orogenic belt between ca. 20° and 27°S. T2, dominated by shortening on a series of N-trending thrust faults and fault-propagated folds, cut and displaced by the above mentioned NW-trending faults, with geothermal fields hosted at fault intersections and at fold hinges. And T3, characterized by transtension accommodated by NW-to-WNW-trending left-lateral/normal faults, with hot-springs lying along the fault traces. Interestingly, each of the independently defined tectonic environments has distinctive helium (in fluids) and strontium (in lavas) isotopic signatures and estimated geothermal reservoir temperatures. T1 shows a large 4He contribution, low 87Sr/86Sr ratio and temperatures varying between ca. 220°-310°C; T3 low 4He and high 87Sr/86Sr ratio and temperature (260°-320°C); T2 isotopic values fall between T1 and T3, yet showing the lowest (130°-250°C) temperatures. We suggest that these particular isotopic signatures are due to a strong structural control on the hot reservoir location and meteoric water content, T3 allowing deeper hot fluid provenances and T1 more meteoric influx.
The Interplay Between Saline Fluid Flow and Dynamic Permeability in Magmatic-Hydrothermal Systems

NASA Astrophysics Data System (ADS)

Weis, P.

2014-12-01

Magmatic-hydrothermal ore deposits document the interplay between saline fluid flow and rock permeability. Numerical simulations of multi-phase flow of variably miscible, compressible H20-NaCl fluids in concert with a dynamic permeability model can reproduce characteristics of porphyry copper and epithermal gold systems. This dynamic permeability model incorporates depth-dependent permeability profiles characteristic for tectonically active crust as well as pressure- and temperature-dependent relationships describing hydraulic fracturing and the transition from brittle to ductile rock behavior. In response to focused expulsion of magmatic fluids from a crystallizing upper crustal magma chamber, the hydrothermal system self-organizes into a hydrological divide, separating an inner part dominated by ascending magmatic fluids under near-lithostatic pressures from a surrounding outer part dominated by convection of colder meteoric fluids under near-hydrostatic pressures. This hydrological divide also provides a mechanism to transport magmatic salt through the crust, and prevents the hydrothermal system to become "clogged" by precipitation of solid halite due to depressurization of saline, high-temperature magmatic fluids. The same physical processes at similar permeability ranges, crustal depths and flow rates are relevant for a number of active systems, including geothermal resources and excess degassing at volcanos. The simulations further suggest that the described mechanism can separate the base of free convection in high-enthalpy geothermal systems from the magma chamber as a driving heat source by several kilometers in the vertical direction in tectonic settings with hydrous magmatism. This hydrology would be in contrast to settings with anhydrous magmatism, where the base of the geothermal systems may be closer to the magma chamber.
Systematic Review of Life Cycle Greenhouse Gas Emissions from Geothermal Electricity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eberle, Annika; Heath, Garvin A.; Carpenter Petri, Alberta C.

The primary goal of this work was to assess the magnitude and variability of published life cycle greenhouse gas (GHG) emission estimates for three types of geothermal electricity generation technologies: enhanced geothermal systems (EGS) binary, hydrothermal (HT) flash, and HT binary. These technologies were chosen to align the results of this report with technologies modeled in National Renewable Energy Laboratory's (NREL's) Regional Energy Deployment Systems (ReEDs) model. Although we did gather and screen life cycle assessment (LCA) literature on hybrid systems, dry steam, and two geothermal heating technologies, we did not analyze published GHG emission estimates for these technologies. Inmore » our systematic literature review of the LCA literature, we screened studies in two stages based on a variety of criteria adapted from NREL's Life Cycle Assessment (LCA) Harmonization study (Heath and Mann 2012). Of the more than 180 geothermal studies identified, only 29 successfully passed both screening stages and only 26 of these included estimates of life cycle GHG emissions. We found that the median estimate of life cycle GHG emissions (in grams of carbon dioxide equivalent per kilowatt-hour generated [g CO2eq/kWh]) reported by these studies are 32.0, 47.0, and 11.3 for EGS binary, HT flash, and HT binary, respectively (Figure ES-1). We also found that the total life cycle GHG emissions are dominated by different stages of the life cycle for different technologies. For example, the GHG emissions from HT flash plants are dominated by the operations phase owing to the flash cycle being open loop whereby carbon dioxide entrained in the geothermal fluids is released to the atmosphere. This is in contrast to binary plants (using either EGS or HT resources), whose GHG emissions predominantly originate in the construction phase, owing to its closed-loop process design. Finally, by comparing this review's literature-derived range of HT flash GHG emissions to data from currently operating geothermal plants, we found that emissions from operational plants exhibit more variability and the median of emissions from operational plants is twice the median of operational emissions reported by LCAs. Further investigation is warranted to better understand the cause of differences between published LCAs and estimates from operational plants and to develop LCA analytical approaches that can yield estimates closer to actual emissions.« less
Coupling geophysical investigation with hydrothermal modeling to constrain the enthalpy classification of a potential geothermal resource.

USGS Publications Warehouse

White, Jeremy T.; Karakhanian, Arkadi; Connor, Chuck; Connor, Laura; Hughes, Joseph D.; Malservisi, Rocco; Wetmore, Paul

2015-01-01

An appreciable challenge in volcanology and geothermal resource development is to understand the relationships between volcanic systems and low-enthalpy geothermal resources. The enthalpy of an undeveloped geothermal resource in the Karckar region of Armenia is investigated by coupling geophysical and hydrothermal modeling. The results of 3-dimensional inversion of gravity data provide key inputs into a hydrothermal circulation model of the system and associated hot springs, which is used to evaluate possible geothermal system configurations. Hydraulic and thermal properties are specified using maximum a priori estimates. Limited constraints provided by temperature data collected from an existing down-gradient borehole indicate that the geothermal system can most likely be classified as low-enthalpy and liquid dominated. We find the heat source for the system is likely cooling quartz monzonite intrusions in the shallow subsurface and that meteoric recharge in the pull-apart basin circulates to depth, rises along basin-bounding faults and discharges at the hot springs. While other combinations of subsurface properties and geothermal system configurations may fit the temperature distribution equally well, we demonstrate that the low-enthalpy system is reasonably explained based largely on interpretation of surface geophysical data and relatively simple models.
Geologic map of the Lassen region, Cascade Range, USA

USGS Publications Warehouse

Clynne, Michael; Muffler, L.J.

1990-01-01

A preliminary geologic map at 1:50,000 of the Lassen region encompasses 1400 km2. The map displays many small, monogenetic volcanoes of basalt to andesite as well as three major late Pliocene and Quaternary volcanic centers that have erupted products ranging from basaltic andesite to rhyolite. The youngest of these volcanic centers is the Lassen volcanic center, active from 600,000 years B.P. to the present. A major caldera formed at 400,000 years B.P. and has subsequently been filled with silicic lavas. The Lassen geothermal system, which consists of a central vapor-dominated reservoir at a temperature of 235??C underlain by a reservoir of hot water, is centered at Bumpass Hell within Lassen Volcanic National Park.
Chlorine isotope geochemistry of Icelandic thermal fluids: Implications for geothermal system behavior at divergent plate boundaries

NASA Astrophysics Data System (ADS)

Stefánsson, Andri; Barnes, Jaime D.

2016-09-01

The chlorine isotope composition of thermal fluids from Iceland were measured in order to evaluate the source of chlorine and possible chlorine isotope fractionation in geothermal systems at divergent plate boundaries. The geothermal systems studied have a wide range of reservoir temperatures from 40 to 437 °C and in-situ pH of 6.15 to 7.15. Chlorine concentrations range from 5.2 to 171 ppm and δ37 Cl values are -0.3 to + 2.1 ‰ (n = 38). The δ37 Cl values of the thermal fluids are interpreted to reflect the source of the chlorine in the fluids. Geothermal processes such as secondary mineral formation, aqueous and vapor speciation and boiling were found to have minimal effects on the δ37 Cl values. However, further work is needed on incorporation of Cl into secondary minerals and its effect on Cl isotope fractionation. Results of isotope geochemical modeling demonstrate that the range of δ37 Cl values documented in the natural thermal fluids can be explained by leaching of the basaltic rocks by meteoric source water under geothermal conditions. Magmatic gas partitioning may also contribute to the source of Cl in some cases. The range of δ37 Cl values of the fluids result mainly from the large range of δ37 Cl values observed for Icelandic basalts, which range from -0.6 to + 1.2 ‰.
Isotope systematics of Icelandic thermal fluids

NASA Astrophysics Data System (ADS)

Stefánsson, Andri; Hilton, David R.; Sveinbjörnsdóttir, Árný E.; Torssander, Peter; Heinemeier, Jan; Barnes, Jaime D.; Ono, Shuhei; Halldórsson, Sæmundur Ari; Fiebig, Jens; Arnórsson, Stefán

2017-05-01

Thermal fluids in Iceland range in temperature from < 10 °C to > 440 °C and are dominated by water (> 97 mol%) with a chloride concentration from < 10 ppm to > 20,000 ppm. The isotope systematics of the fluids reveal many important features of the source(s) and transport properties of volatiles at this divergent plate boundary. Studies spanning over four decades have revealed a large range of values for δD (- 131 to + 3.3‰), tritium (- 0.4 to + 13.8 TU), δ18O (- 20.8 to + 2.3‰), 3He/4He (3.1 to 30.4 RA), δ11B (- 6.7 to + 25.0‰), δ13C∑ CO2 (- 27.4 to + 4.6‰), 14C∑ CO2 (+ 0.6 to + 118 pMC), δ13CCH4 (- 52.3 to - 17.8‰), δ15N (- 10.5 to + 3.0‰), δ34S∑ S- II (- 10.9 to + 3.4‰), δ34SSO4 (- 2.0 to + 21.2‰) and δ37Cl (- 1.0 to + 2.1‰) in both liquid and vapor phases. Based on this isotopic dataset, the thermal waters originate from meteoric inputs and/or seawater. For other volatiles, degassing of mantle-derived melts contributes to He, CO2 and possibly also to Cl in the fluids. Water-basalt interaction also contributes to CO2 and is the major source of H2S, SO4, Cl and B in the fluids. Redox reactions additionally influence the composition of the fluids, for example, oxidation of H2S to SO4 and reduction of CO2 to CH4. Air-water interaction mainly controls N2, Ar and Ne concentrations. The large range of many non-reactive volatile isotope ratios, such as δ37Cl and 3He/4He, indicate heterogeneity of the mantle and mantle-derived melts beneath Iceland. In contrast, the large range of many reactive isotopes, such as δ13C∑ CO2 and δ34S∑ S- II, are heavily affected by processes occurring within the geothermal systems, including fluid-rock interaction, depressurization boiling, and isotopic fractionation between secondary minerals and the aqueous and vapor species. Variations due to these geothermal processes may exceed differences observed among various crust and mantle sources, highlighting the importance and effects of chemical reactions on the isotope systematics of reactive elements.
Monitoring environmental and related performance parameters for a Rankine-cycle turbine electric generator utilizing geothermal energy at the Gila Hot Springs, New Mexico

NASA Astrophysics Data System (ADS)

Starkey, A. H.; Icerman, L.

1984-08-01

The environmental effects associated with the operation of a privately owned Rankine-cycle turbogenerator unit using low temperature geothermal resources in the form of free-flowing hot springs to produce electricity in a remote, rural area were studied. The following conclusions pertain to the operation of the turbogenerator system: (1) the heat exchanger could not provide sufficient freon vapor at the required pressures to provide adequate thermal input to the turbine; (2) conversion or redesign of the condenser and return pump to function adequately represents a problem of unknown difficulty; (3) all pressure and heat transfer tests indicated that a custom designed heat exchanger built on-site would provide adequate vapor at pressures high enough to power a 10-kW (sub e) or perhaps larger generator; and (4) automated control systems are needed for the hot and cold water supplies and the freon return pump.
Phase 0 study for a geothermal superheated water proof of concept facility

NASA Technical Reports Server (NTRS)

Douglass, R. H.; Pearson, R. O.

1974-01-01

A Phase 0 study for the selection of a representative liquid-dominated geothermal resource of moderate salinity and temperature is discussed. Selection and conceptual design of a nominal 10-MWe energy conversion system, and implementation planning for Phase 1: subsystem (component, experiments) and Phase 2: final design, construction, and operation of experimental research facilities are reported. The objective of the overall program is to demonstrate the technical and economic viability of utilizing moderate temperature and salinity liquid-dominated resources with acceptable environmental impact, and thus encourage commercial scale development of geothermal electrical power generation.
DEVELOPMENT OF A SOFTWARE DESIGN TOOL FOR HYBRID SOLAR-GEOTHERMAL HEAT PUMP SYSTEMS IN HEATING- AND COOLING-DOMINATED BUILDINGS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yavuzturk, C. C.; Chiasson, A. D.; Filburn, T. P.

This project provides an easy-to-use, menu-driven, software tool for designing hybrid solar-geothermal heat pump systems (GHP) for both heating- and cooling-dominated buildings. No such design tool currently exists. In heating-dominated buildings, the design approach takes advantage of glazed solar collectors to effectively balance the annual thermal loads on the ground with renewable solar energy. In cooling-dominated climates, the design approach takes advantage of relatively low-cost, unglazed solar collectors as the heat rejecting component. The primary benefit of hybrid GHPs is the reduced initial cost of the ground heat exchanger (GHX). Furthermore, solar thermal collectors can be used to balance themore » ground loads over the annual cycle, thus making the GHX fully sustainable; in heating-dominated buildings, the hybrid energy source (i.e., solar) is renewable, in contrast to a typical fossil fuel boiler or electric resistance as the hybrid component; in cooling-dominated buildings, use of unglazed solar collectors as a heat rejecter allows for passive heat rejection, in contrast to a cooling tower that consumes a significant amount of energy to operate, and hybrid GHPs can expand the market by allowing reduced GHX footprint in both heating- and cooling-dominated climates. The design tool allows for the straight-forward design of innovative GHP systems that currently pose a significant design challenge. The project lays the foundations for proper and reliable design of hybrid GHP systems, overcoming a series of difficult and cumbersome steps without the use of a system simulation approach, and without an automated optimization scheme. As new technologies and design concepts emerge, sophisticated design tools and methodologies must accompany them and be made usable for practitioners. Lack of reliable design tools results in reluctance of practitioners to implement more complex systems. A menu-driven software tool for the design of hybrid solar GHP systems is provided that is based on mathematically robust, validated models. An automated optimization tool is used to balance ground loads and incorporated into the simulation engine. With knowledge of the building loads, thermal properties of the ground, the borehole heat exchanger configuration, the heat pump peak hourly and seasonal COP for heating and cooling, the critical heat pump design entering fluid temperature, and the thermal performance of a solar collector, the total GHX length can be calculated along with the area of a supplemental solar collector array and the corresponding reduced GHX length. An economic analysis module allows for the calculation of the lowest capital cost combination of solar collector area and GHX length. ACKNOWLEDGMENTS This project was funded by the United States Department of Energy DOE-DE-FOA-0000116, Recovery Act Geothermal Technologies Program: Ground Source Heat Pumps. The lead contractor, The University of Hartford, was supported by The University of Dayton, and the Oak Ridge National Laboratories. All funding and support for this project as well as contributions of graduate and undergraduate students from the contributing institutions are gratefully acknowledged.« less
Tectonic and Structural Controls of Geothermal Activity in the Great Basin Region, Western USA

NASA Astrophysics Data System (ADS)

Faulds, J. E.; Hinz, N.; Kreemer, C. W.

2012-12-01

We are conducting a thorough inventory of structural settings of geothermal systems (>400 total) in the extensional to transtensional Great Basin region of the western USA. Most of the geothermal systems in this region are not related to upper crustal magmatism and thus regional tectonic and local structural controls are the most critical factors controlling the locations of the geothermal activity. A system of NW-striking dextral faults known as the Walker Lane accommodates ~20% of the North American-Pacific plate motion in the western Great Basin and is intimately linked to N- to NNE-striking normal fault systems throughout the region. Overall, geothermal systems are concentrated in areas with the highest strain rates within or proximal to the eastern and western margins of the Great Basin, with the high temperature systems clustering in transtensional areas of highest strain rate in the northwestern Great Basin. Enhanced extension in the northwestern Great Basin probably results from the northwestward termination of the Walker Lane and the concomitant transfer of dextral shear into west-northwest directed extension, thus producing a broad transtensional region. The capacity of geothermal power plants also correlates with strain rates, with the largest (hundreds of megawatts) along the Walker Lane or San Andreas fault system, where strain rates range from 10-100 nanostrain/yr to 1,000 nanostrain/yr, respectively. Lesser systems (tens of megawatts) reside in the Basin and Range (outside the Walker Lane), where local strain rates are typically < 10 nanostrain/yr. Of the 250+ geothermal fields catalogued, step-overs or relay ramps in normal fault zones serve as the most favorable setting, hosting ~32% of the systems. Such areas have multiple, overlapping fault strands, increased fracture density, and thus enhanced permeability. Other common settings include a) intersections between normal faults and strike-slip or oblique-slip faults (27%), where multiple minor faults connect major structures and fluids can flow readily through highly fractured, dilational quadrants, and b) normal fault terminations or tip-lines (22%), where horse-tailing generates closely-spaced faults and increased permeability. Other settings include accommodation zones (i.e., belts of intermeshing, oppositely dipping normal faults; 8%), major range-front faults (5-6%), and pull-aparts in strike-slip faults (4%). In addition, Quaternary faults lie within or near most systems. The relative scarcity of geothermal systems along displacement-maxima of major normal faults may be due to reduced permeability in thick zones of clay gouge and periodic release of stress in major earthquakes. Step-overs, terminations, intersections, and accommodation zones correspond to long-term, critically stressed areas, where fluid pathways are more likely to remain open in networks of closely-spaced, breccia-dominated fractures. These findings may help guide future exploration efforts, especially for blind geothermal systems, which probably comprise the bulk of the geothermal resources in the Great Basin.
Liquid-vapor relations for the system NaCl-H2O: summary of the P-T- x surface from 300° to 500°C

USGS Publications Warehouse

Bischoff, J.L.; Pitzer, Kenneth S.

1989-01-01

Experimental data on the vapor-liquid equilibrium relations for the system NaCl-H2O were compiled and compared in order to provide an improved estimate of the P-T-x surface between 300° to 500°C, a range for which the system changes from subcritical to critical behavior. Data for the three-phase curve (halite + liquid + vapor) and the NaCl-H2O critical curve were evaluated, and the best fits for these extrema then were used to guide selection of best fit for isothermal plots for the vapor-liquid region in-between. Smoothing was carried out in an iterative procedure by replotting the best-fit data as isobars and then as isopleths, until an internally consistent set of data was obtained. The results are presented in table form that will have application to theoretical modelling and to the understanding of two-phase behavior in saline geothermal systems.
Sedimentary and Enhanced Geothermal Systems | Geothermal Technologies |

Science.gov Websites

NREL Sedimentary and Enhanced Geothermal Systems Sedimentary and Enhanced Geothermal Systems To innovative technologies, such as sedimentary and enhanced geothermal systems (EGS). Photo of a geothermal power plant in Imperial California. Capabilities To advance EGS and sedimentary geothermal systems, NREL
Ancient Systems of Sodium/Potassium Homeostasis as Predecessors of Membrane Bioenergetics.

PubMed

Dibrova, D V; Galperin, M Y; Koonin, E V; Mulkidjanian, A Y

2015-05-01

Cell cytoplasm of archaea, bacteria, and eukaryotes contains substantially more potassium than sodium, and potassium cations are specifically required for many key cellular processes, including protein synthesis. This distinct ionic composition and requirements have been attributed to the emergence of the first cells in potassium-rich habitats. Different, albeit complementary, scenarios have been proposed for the primordial potassium-rich environments based on experimental data and theoretical considerations. Specifically, building on the observation that potassium prevails over sodium in the vapor of inland geothermal systems, we have argued that the first cells could emerge in the pools and puddles at the periphery of primordial anoxic geothermal fields, where the elementary composition of the condensed vapor would resemble the internal milieu of modern cells. Marine and freshwater environments generally contain more sodium than potassium. Therefore, to invade such environments, while maintaining excess of potassium over sodium in the cytoplasm, primordial cells needed means to extrude sodium ions. The foray into new, sodium-rich habitats was the likely driving force behind the evolution of diverse redox-, light-, chemically-, or osmotically-dependent sodium export pumps and the increase of membrane tightness. Here we present a scenario that details how the interplay between several, initially independent sodium pumps might have triggered the evolution of sodium-dependent membrane bioenergetics, followed by the separate emergence of the proton-dependent bioenergetics in archaea and bacteria. We also discuss the development of systems that utilize the sodium/potassium gradient across the cell membranes.
Effect of microporosity on the permeability of geothermal systems, case study of Los Humeros geothermal fie

NASA Astrophysics Data System (ADS)

Carrasco, Gerardo; Cid, Hector; Ortega, Dante

2017-04-01

Los Humeros is the largest silicic caldera complex of the Trans-Mexican Volcanic Belt (TMVB), with an active geothermal field, which is currently producing around 65 MW. It is located in the northern part of the eastern TMVB. Its evolution includes voluminous caldera-forming eruption producing two large caldera structures (Los Humeros and Los Potreros calderas) with alternated episodes of effusive and explosive activity until the Holocene. The geothermal reservoir is located at a depth of about 1,500 m comprising a thick succession of porphyritic andesitic lava flows, and perhaps which overlay in a highly discordant contact a meta-sedimentary basement sequence dominated by altered limestone and skarn rocks. A NW/N-S structural system seems to be the main control of geothermal field distribution within the central part of the youngest caldera. Permeability in the geothermal reservoir has been associated with that system observed on the surficial geology, but also to some hidden secondary faulting and associated fracturing. Primary porosity has been considered negligible due to the low macroporosity observed in the volcanic rocks. However, a detailed analysis of the microporosity determined by X-ray microtomography new developed techniques, allow us to determine precise values of microporosity that were using for numerical simulation to obtain values of effective porosity, which reveals an interesting alternative solution to the permeability of the subsurface of Los Humeros geothermal field that should be taking into account to the final permeability of the system.
Subsurface Thermal Energy Storage for Improved Air Conditioning Efficiency

DTIC Science & Technology

2016-11-01

current cost liability is the potential for several significant structural changes at DoD facilities around the world. These challenges include... climate , with an average high temperature of 90 degrees in July, and an average low temperature of 39 in January. The annual average temperature is 65.6...in new systems. The first three steps are recommended for every geothermal system installed in cooling dominated areas ( climatically hot areas such
Isotopic constraints on ice age fluids in active geothermal systems: Reykjanes, Iceland

NASA Astrophysics Data System (ADS)

Pope, Emily C.; Bird, Dennis K.; Arnórsson, Stefán; Fridriksson, Thráinn; Elders, Wilfred A.; Fridleifsson, Gudmundur Ó.

2009-08-01

The Reykjanes geothermal system is located on the landward extension of the Mid-Atlantic Ridge in southwest Iceland, and provides an on-land proxy to high-temperature hydrothermal systems of oceanic spreading centers. Previous studies of elemental composition and salinity have shown that Reykjanes geothermal fluids are likely hydrothermally modified seawater. However, δD values of these fluids are as low as -23‰, which is indicative of a meteoric water component. Here we constrain the origin of Reykjanes hydrothermal solutions by analysis of hydrogen and oxygen isotope compositions of hydrothermal epidote from geothermal drillholes at depths between 1 and 3 km. δDEPIDOTE values from wells RN-8, -9, -10 and -17 collectively range from -60 to -78‰, and δ18OEPIDOTE in these wells are between -3.0 and 2.3‰. The δD values of epidote generally increase along a NE trend through the geothermal field, whereas δ18O values generally decrease, suggesting a southwest to northeast migration of the geothermal upflow zone with time that is consistent with present-day temperatures and observed hydrothermal mineral zones. For comparative analysis, the meteoric-water dominated Nesjavellir and Krafla geothermal systems, which have a δDFLUID of ˜ -79‰ and -89‰, respectively, show δDEPIDOTE values of -115‰ and -125‰. In contrast, δDEPIDOTE from the mixed meteoric-seawater Svartsengi geothermal system is -68‰; comparable to δDEPIDOTE from well RN-10 at Reykjanes. Stable isotope compositions of geothermal fluids in isotopic equilibrium with the epidotes at Reykjanes are computed using published temperature dependent hydrogen and oxygen isotope fractionation curves for epidote-water, measured isotope composition of the epidotes and temperatures approximated from the boiling point curve with depth. Calculated δD and δ18O of geothermal fluids are less than 0‰, suggesting that fluids of meteoric or glacial origin are a significant component of the geothermal solutions. Additionally, δDFLUID values in equilibrium with geothermal epidote are lower than those of modern-day fluids, whereas calculated δ18OFLUID values are within range of the observed fluid isotope composition. We propose that modern δDEPIDOTE and δDFLUID values are the result of diffusional exchange between hydrous alteration minerals that precipitated from glacially-derived fluids early in the evolution of the Reykjanes system and modern seawater-derived geothermal fluids. A simplified model of isotope exchange in the Reykjanes geothermal system, in which the average starting δDROCK value is -125‰ and the water to rock mass ratio is 0.25, predicts a δDFLUID composition within 1‰ of average measured values. This model resolves the discrepancy between fluid salinity and isotope composition of Reykjanes geothermal fluids, explains the observed disequilibrium between modern fluids and hydrothermal epidote, and suggests that rock-fluid interaction is the dominant control over the evolution of fluid isotope composition in the hydrothermal system.

Geothermal systems: Principles and case histories

NASA Astrophysics Data System (ADS)

Rybach, L.; Muffler, L. J. P.

The classification of geothermal systems is considered along with the geophysical and geochemical signatures of geothermal systems, aspects of conductive heat transfer and regional heat flow, and geothermal anomalies and their plate tectonic framework. An investigation of convective heat and mass transfer in hydrothermal systems is conducted, taking into account the mathematical modelling of hydrothermal systems, aspects of idealized convective heat and mass transport, plausible models of geothermal reservoirs, and preproduction models of hydrothermal systems. Attention is given to the prospecting for geothermal resources, the application of water geochemistry to geothermal exploration and reservoir engineering, heat extraction from geothermal reservoirs, questions of geothermal resource assessment, and environmental aspects of geothermal energy development. A description is presented of a number of case histories, taking into account the low enthalpy geothermal resource of the Pannonian Basin in Hungary, the Krafla geothermal field in Northeast Iceland, the geothermal system of the Jemez Mountains in New Mexico, and extraction-reinjection at the Ahuachapan geothermal field in El Salvador.
Direct contact, binary fluid geothermal boiler

DOEpatents

Rapier, P.M.

1979-12-27

Energy is extracted from geothermal brines by direct contact with a working fluid such as isobutane which is immiscible with the brine in a geothermal boiler. The geothermal boiler provides a distributor arrangement which efficiently contacts geothermal brine with the isobutane in order to prevent the entrainment of geothermal brine in the isobutane vapor which is directed to a turbine. Accordingly the problem of brine carryover through the turbine causing corrosion and scaling thereof is eliminated. Additionally the heat exchanger includes straightening vanes for preventing startup and other temporary fluctuations in the transitional zone of the boiler from causing brine carryover into the turbine. Also a screen is provided in the heat exchanger to coalesce the working fluid and to assist in defining the location of the transitional zone where the geothermal brine and the isobutane are initially mixed.
The thermodynamic cycle models for geothermal power plants by considering the working fluid characteristic

NASA Astrophysics Data System (ADS)

Mulyana, Cukup; Adiprana, Reza; Saad, Aswad H.; M. Ridwan, H.; Muhammad, Fajar

2016-02-01

The scarcity of fossil energy accelerates the development of geothermal power plant in Indonesia. The main issue is how to minimize the energy loss from the geothermal working fluid so that the power generated can be increased. In some of geothermal power plant, the hot water which is resulted from flashing is flown to injection well, and steam out from turbine is condensed in condenser, while the temperature and pressure of the working fluid is still high. The aim of this research is how the waste energy can be re-used as energy source to generate electric power. The step of the research is started by studying the characteristics of geothermal fluid out from the well head. The temperature of fluid varies from 140°C - 250°C, the pressure is more than 7 bar and the fluid phase are liquid, gas, or mixing phase. Dry steam power plant is selected for vapor dominated source, single or multiple flash power plant is used for dominated water with temperature > 225°C, while the binary power plant is used for low temperature of fluid < 160°C. Theoretically, the process in the power plant can be described by thermodynamic cycle. Utilizing the heat loss of the brine and by considering the broad range of working fluid temperature, the integrated geothermal power plant has been developed. Started with two ordinary single flash power plants named unit 1 and unit 2, with the temperature 250°C resulting power is W1'+W2'. The power is enhanced by utilizing the steam that is out from first stage of the turbine by inputting the steam to the third stage, the power of the plant increase with W1''+W2" or 10% from the original power. By using flasher, the water from unit 1 and 2 is re-flashed at 200°C, and the steam is used to drive the turbine in unit 3, while the water is re-flashed at the temperature170°C and the steam is flown to the same turbine (unit 3) resulting the power of W3+W4. Using the fluid enthalpy, the calculated power of these double and triple flash power plant are 50% of W1+W2. At the last step, the steam out from the turbine of unit 3 with the temperature 150°C is used as a heat source for binary cycle power plant named unit 4, while the hot water from the flasher is used as a heat source for the other binary cycle named unit 5 resulted power W5+W6 or 15% of W1+W2. Using this integrated model the power increased 75% from the original one.
Soil degassing at the Los Humeros geothermal field (Mexico)

NASA Astrophysics Data System (ADS)

Peiffer, Loïc; Carrasco-Núñez, Gerardo; Mazot, Agnès; Villanueva-Estrada, Ruth Esther; Inguaggiato, Claudio; Bernard Romero, Rubén; Rocha Miller, Roberto; Hernández Rojas, Javier

2018-05-01

The Los Humeros geothermal field is the third most important producer of geothermal electricity (70 MW) in Mexico. Geothermal fluids are hosted in fractured andesitic lavas and mostly consist of high enthalpy steam with limited water content (vapor fraction > 0.9). Despite the high reservoir temperature ( 300-400 °C), thermal manifestations at the surface are scarce and locally appear as steaming grounds, weak steam vents and advanced argillic alteration. Geothermal fluid upflow from the reservoir towards the surface is limited by welded ignimbrite deposits that act as a low-permeability barrier. In this study, we present the first measurements of CO2, CH4 and H2S degassing rates from the soil performed at Los Humeros. Flux measurements were complemented with δ13C composition of degassing CO2 and soil temperatures to discuss gas origin and thermal anomalies. We measured high soil degassing rates (up to 7530 g m-2 d-1 CO2, 33 g m-2 d-1 CH4 and 22 g m-2 d-1 H2S) in three localized areas (Humeros North - HN, Humeros South - HS and Xalapazco - XA) as well as high soil temperatures reaching the boiling temperature at the local altitude (90.6 °C). The particular location of these three areas suggests that the steam-dominated reservoir degases to the surface through permeable faults crossing the ignimbritic deposits. The remaining surveyed areas are characterized by weak CO2 fluxes (≤44 g m-2 d-1), non-detectable CH4 and H2S fluxes, and lower soil temperatures (5-21 °C). The compositions in δ13CCO2 from HN-HS-XA areas (δ13CCO2 = -7.94 to -2.73‰) reflect a magmatic source with some possible contribution from the sedimentary basement, as well as fractionation induced by boiling and CO2 dissolution in shallow water bodies. We also discuss the processes causing the spread in CO2/CH4 flux ratios. Finally, we estimate the heat output from the three high degassing areas to a value of 16.4 MWt.
Direct contact, binary fluid geothermal boiler

DOEpatents

Rapier, Pascal M.

1982-01-01

Energy is extracted from geothermal brines by direct contact with a working fluid such as isobutane which is immiscible with the brine in a geothermal boiler. The geothermal boiler provides a distributor arrangement which efficiently contacts geothermal brine with the isobutane in order to prevent the entrainment of geothermal brine in the isobutane vapor which is directed to a turbine. Accordingly the problem of brine carry-over through the turbine causes corrosion and scaling thereof is eliminated. Additionally the heat exchanger includes straightening vanes for preventing startup and other temporary fluctuations in the transitional zone of the boiler from causing brine carryover into the turbine. Also a screen is provided in the heat exchanger to coalesce the working fluid and to assist in defining the location of the transitional zone where the geothermal brine and the isobutane are initially mixed.
New insight from noble gas and stable isotopes of geothermal/hydrothermal fluids at Caviahue-Copahue Volcanic Complex: Boiling steam separation and water-rock interaction at shallow depth

NASA Astrophysics Data System (ADS)

Roulleau, Emilie; Tardani, Daniele; Sano, Yuji; Takahata, Naoto; Vinet, Nicolas; Bravo, Francisco; Muñoz, Carlos; Sanchez, Juan

2016-12-01

We measured noble gas and stable isotopes of the geothermal and hydrothermal fluids of the Caviahue-Copahue Volcanic Complex (CCVC), one of the most important geothermal systems in Argentina/Chile, in order to provide new insights into fluid circulation and origin. With the exception of Anfiteatro and Chancho-co geothermal systems, mantle-derived helium dominates in the CCVC fluids, with measured 3He/4He ratios up to 7.86Ra in 2015. Their positive δ15N is an evidence for subducted sediment-derived nitrogen, which is commonly observed in subduction settings. Both He-N2-Ar composition and positive correlation between δD-H2O and δ18O-H2O suggest that the fluids from Anfiteatro and Chancho-co (and partly from Pucon-Mahuida as well, on the southern flank of Copahue volcano) represent a meteoric water composition with a minor magmatic contribution. The Ne, Kr and Xe isotopic compositions are entirely of atmospheric origin, but processes of boiling and steam separation have led to fractionation of their elemental abundances. We modeled the CCVC fluid evolution using Rayleigh distillation curves, considering an initial air saturated geothermal water (ASGW) end-member at 250 and 300 °C, followed by boiling and steam separation at lower temperatures (from 200 °C to 150 °C). Between 2014 and 2015, the CCVC hydrogen and oxygen isotopes shifted from local meteoric water-dominated to andesitic water-dominated signature. This shift is associated with an increase of δ13C values and Stotal, HCl and He contents. These characteristics are consistent with a change in the gas ascent pathway between 2014 and 2015, which in turn induced higher magmatic-hydrothermal contribution in the fluid signature. The composition of the magmatic source of the CCVC fluids is: 3He/4He = 7.7Ra, δ15N = + 6‰, and δ13C = - 6.5‰. Mixing models between air-corrected He and N suggest the involvement of 0.5% to 5% of subducted sediments in the magmatic source. The magmatic sulfur isotopic composition is estimated at - 2.38‰ (from COP-2), but most samples show elemental fractionation due to boiling and steam separation followed by various degrees of atmospheric contamination. All these geochemical and isotopic characteristics are the direct consequence of tectonic particularities of the CCVC: NE faults promote the ascent of hydrothermal fluids in the geothermal area whereas WNW faults serve as preferential channels for meteoric water infiltration.
Seismic properties of fluid bearing formations in magmatic geothermal systems: can we directly detect geothermal activity with seismic methods?

NASA Astrophysics Data System (ADS)

Grab, Melchior; Scott, Samuel; Quintal, Beatriz; Caspari, Eva; Maurer, Hansruedi; Greenhalgh, Stewart

2016-04-01

Seismic methods are amongst the most common techniques to explore the earth's subsurface. Seismic properties such as velocities, impedance contrasts and attenuation enable the characterization of the rocks in a geothermal system. The most important goal of geothermal exploration, however, is to describe the enthalpy state of the pore fluids, which act as the main transport medium for the geothermal heat, and to detect permeable structures such as fracture networks, which control the movement of these pore fluids in the subsurface. Since the quantities measured with seismic methods are only indirectly related with the fluid state and the rock permeability, the interpretation of seismic datasets is difficult and usually delivers ambiguous results. To help overcome this problem, we use a numerical modeling tool that quantifies the seismic properties of fractured rock formations that are typically found in magmatic geothermal systems. We incorporate the physics of the pore fluids, ranging from the liquid to the boiling and ultimately vapor state. Furthermore, we consider the hydromechanics of permeable structures at different scales from small cooling joints to large caldera faults as are known to be present in volcanic systems. Our modeling techniques simulate oscillatory compressibility and shear tests and yield the P- and S-wave velocities and attenuation factors of fluid saturated fractured rock volumes. To apply this modeling technique to realistic scenarios, numerous input parameters need to be indentified. The properties of the rock matrix and individual fractures were derived from extensive literature research including a large number of laboratory-based studies. The geometries of fracture networks were provided by structural geologists from their published studies of outcrops. Finally, the physical properties of the pore fluid, ranging from those at ambient pressures and temperatures up to the supercritical conditions, were taken from the fluid physics literature. The results of this study allow us to describe the seismic properties as a function of hydrothermal and geological features. We use it in a forward seismic modeling study to examine how the seismic response changes with temporally and/or spatially varying fluid properties.
Temperature-profile methods for estimating percolation rates in arid environments

USGS Publications Warehouse

Constantz, Jim; Tyler, Scott W.; Kwicklis, Edward

2003-01-01

Percolation rates are estimated using vertical temperature profiles from sequentially deeper vadose environments, progressing from sediments beneath stream channels, to expansive basin-fill materials, and finally to deep fractured bedrock underlying mountainous terrain. Beneath stream channels, vertical temperature profiles vary over time in response to downward heat transport, which is generally controlled by conductive heat transport during dry periods, or by advective transport during channel infiltration. During periods of stream-channel infiltration, two relatively simple approaches are possible: a heat-pulse technique, or a heat and liquid-water transport simulation code. Focused percolation rates beneath stream channels are examined for perennial, seasonal, and ephemeral channels in central New Mexico, with estimated percolation rates ranging from 100 to 2100 mm d−1 Deep within basin-fill and underlying mountainous terrain, vertical temperature gradients are dominated by the local geothermal gradient, which creates a profile with decreasing temperatures toward the surface. If simplifying assumptions are employed regarding stratigraphy and vapor fluxes, an analytical solution to the heat transport problem can be used to generate temperature profiles at specified percolation rates for comparison to the observed geothermal gradient. Comparisons to an observed temperature profile in the basin-fill sediments beneath Frenchman Flat, Nevada, yielded water fluxes near zero, with absolute values <10 mm yr−1 For the deep vadose environment beneath Yucca Mountain, Nevada, the complexities of stratigraphy and vapor movement are incorporated into a more elaborate heat and water transport model to compare simulated and observed temperature profiles for a pair of deep boreholes. Best matches resulted in a percolation rate near zero for one borehole and 11 mm yr−1 for the second borehole.
The calculation of aquifer chemistry in hot-water geothermal systems

USGS Publications Warehouse

Truesdell, Alfred H.; Singers, Wendy

1974-01-01

The temperature and chemical conditions (pH, gas pressure, and ion activities) in a geothermal aquifer supplying a producing bore can be calculated from the enthalpy of the total fluid (liquid + vapor) produced and chemical analyses of water and steam separated and collected at known pressures. Alternatively, if a single water phase exists in the aquifer, the complete analysis (including gases) of a sample collected from the aquifer by a downhole sampler is sufficient to determine the aquifer chemistry without a measured value of the enthalpy. The assumptions made are that the fluid is produced from a single aquifer and is homogeneous in enthalpy and chemical composition. These calculations of aquifer chemistry involving large amounts of ancillary information and many iterations require computer methods. A computer program in PL-1 to perform these calculations is available from the National Technical Information Service as document PB-219 376.
Hot and Steamy Fractures in the Philippines: The Geological Characterization and Permeability Evaluation of Fractures in the Southern Negros Geothermal Field, Philippines

NASA Astrophysics Data System (ADS)

Pastoriza, L. R.; Holdsworth, R.; McCaffrey, K. J. W.; Dempsey, E. D.; Walker, R. J.; Gluyas, J.; Reyes, J. K.

2016-12-01

Fluid flow pathway characterization is critical to geothermal exploration and exploitation. It requires a good understanding of the structural evolution, fault distribution and fluid flow properties. A dominantly fieldwork-based approach has been used to evaluate the potential fracture permeability characteristics of a typical high-temperature geothermal reservoir in the Southern Negros Geothermal Field, Philippines. This is a liquid-dominated geothermal resource hosted in the andesitic to dacitic Quaternary Cuernos de Negros Volcano in Negros Island. Fieldwork reveals two main fracture groups based on fault rock characteristics, alteration type, relative age of deformation, and associated thermal manifestation, with the younger fractures mainly related to the development of the modern geothermal system. Palaeostress analyses of cross-cutting fault and fracture arrays reveal a progressive counterclockwise rotation of stress axes from the (?)Pliocene up to the present-day, which is consistent with the regional tectonic models. A combined slip and dilation tendency analysis of the mapped faults indicates that NW-SE structures should be particularly promising drilling targets. Frequency versus length and aperture plots of fractures across six to eight orders of magnitude show power-law relationships with a change in scaling exponent in the region of 100 to 500m length-scales. Finally, evaluation of the topology of the fracture branches shows the dominance of Y-nodes that are mostly doubly connected suggesting good connectivity and permeability within the fracture networks. The results obtained in this study illustrate the value of methods that can be globally applied during exploration to better characterize fracture systems in geothermal reservoirs using multiscale datasets.
Hot and steamy fractures in the Philippines: the characterisation and permeability evaluation of fractures of the Southern Negros Geothermal Field, Negros Oriental, Philippines

NASA Astrophysics Data System (ADS)

Pastoriza, Loraine; Holdsworth, Robert; McCaffrey, Kenneth; Dempsey, Eddie; Walker, Richard; Gluyas, Jon; Reyes, Jonathan

2017-04-01

Fluid flow pathway characterisation is critical to geothermal exploration and exploitation. It requires a good understanding of the structural evolution, fault distribution and fluid flow properties. A dominantly fieldwork-based approach has been used to evaluate the potential fracture permeability characteristics of a typical high-temperature geothermal reservoir in the Southern Negros Geothermal Field, Philippines. This is a liquid-dominated geothermal resource hosted in the andesitic to dacitic Quaternary Cuernos de Negros Volcano in Negros Island. Fieldwork reveals two main fracture groups based on fault rock characteristics, alteration type, relative age of deformation, and associated thermal manifestation, with the younger fractures mainly related to the development of the modern geothermal system. Palaeostress analyses of cross-cutting fault and fracture arrays reveal a progressive counterclockwise rotation of stress axes from the (?)Pliocene up to the present-day, which is consistent with the regional tectonic models. A combined slip and dilation tendency analysis of the mapped faults indicates that NW-SE structures should be particularly promising drilling targets. Frequency versus length and aperture plots of fractures across six to eight orders of magnitude show power-law relationships with a change in scaling exponent in the region of 100 to 500m length-scales. Finally, evaluation of the topology of the fracture branches shows the dominance of Y-nodes that are mostly doubly connected suggesting good connectivity and permeability within the fracture networks. The results obtained in this study illustrate the value of methods that can be globally applied during exploration to better characterize fracture systems in geothermal reservoirs using multiscale datasets.
Structural Controls of the Tuscarora Geothermal Field, Elko County, Nevada

NASA Astrophysics Data System (ADS)

Dering, Gregory M.

Detailed geologic mapping, structural analysis, and well data have been integrated to elucidate the stratigraphic framework and structural setting of the Tuscarora geothermal area. Tuscarora is an amagmatic geothermal system that lies in the northern part of the Basin and Range province, ˜15 km southeast of the Snake River Plain and ˜90 km northwest of Elko, Nevada. The Tuscarora area is dominated by late Eocene to middle Miocene volcanic and sedimentary rocks, all overlying Paleozoic metasedimentary rocks. A geothermal power plant was constructed in 2011 and currently produces 18 MWe from an ˜170°C reservoir in metasedimentary rocks at a depth of 1740 m. Analysis of drill core reveals that the subsurface geology is dominated to depths of ˜700-1000 m by intracaldera deposits of the Eocene Big Cottonwood Canyon caldera, including blocks of basement-derived megabreccia. Furthermore, the Tertiary-Paleozoic nonconformity within the geothermal field has been recognized as the margin of this Eocene caldera. Structural relations combined with geochronologic data from previous studies indicate that Tuscarora has undergone extension since the late Eocene, with significant extension in the late Miocene-Pliocene to early Pleistocene. Kinematic analysis of fault slip data reveal an east-west-trending least principal paleostress direction, which probably reflects an earlier episode of Miocene extension. Two distinct structural settings at different scales appear to control the geothermal field. The regional structural setting is a 10-km wide complexly faulted left step or relay ramp in the west-dipping range-bounding Independence-Bull Run Mountains normal fault system. Geothermal activity occurs within the step-over where sets of east- and west-dipping normal faults overlap in a northerly trending accommodation zone. The distribution of hot wells and hydrothermal surface features, including boiling springs, fumaroles, and siliceous sinter, indicate that the geothermal system is restricted to the narrow (< 1 km) axial part of the accommodation zone, where permeability is maintained at depth around complex fault intersections. Shallow up-flow appears to be focused along several closely spaced steeply west-dipping north-northeast-striking normal faults within the axial part of the accommodation zone. These faults are favorably oriented for extension and fluid flow under the present-day northwest-trending regional extension direction indicated by previous studies of GPS geodetic data, earthquake focal mechanisms, and kinematic data from late Quaternary faults. The recognition of the axial part of an accommodation zone as a favorable structural setting for geothermal activity may be a useful exploration tool for development of drilling targets in extensional terranes, as well as for developing geologic models of known geothermal fields. Preliminary analysis of broad step-overs similar to Tuscarora reveals that geothermal activity occurs in a variety of subsidiary structural settings within these regions. In addition, the presence of several high-temperature systems in northeastern Nevada demonstrates the viability of electrical-grade geothermal activity in this region despite low present-day strain rates as indicated by GPS geodetic data. Geothermal exploration potential in northeastern Nevada may therefore be higher than previously recognized.
Age and thermal history of the Geysers plutonic complex (felsite unit), Geysers geothermal field, California: A 40Ar/39Ar and U-Pb study

USGS Publications Warehouse

Dalrymple, G.B.; Grove, M.; Lovera, O.M.; Harrison, T.M.; Hulen, J.B.; Lanphere, M.A.

1999-01-01

Sixty-nine ion microprobe spot analyses of zircons from four granite samples from the plutonic complex that underlies the Geysers geothermal field yield 207Pb/206Pb vs. 238U/206Pb concordia ages ranging from 1.13 ?? 0.04 Ma to 1.25 ?? 0.04 (1??) Ma. The weighted mean of the U/Pb model ages is 1.18 ?? 0.03 Ma. The U-Pb ages coincide closely with 40Ar/39Ar age spectrum plateau and 'terminal' ages from coexisting K-feldspars and with the eruption ages of overlying volcanic rocks. The data indicate that the granite crystallized at 1.18 Ma and had cooled below 350??C by ~0.9-1.0 Ma. Interpretation of the feldspar 40Ar/39Ar age data using multi-diffusion domain theory indicates that post-emplacement rapid cooling was succeeded either by slower cooling from 350??to 300??C between 1.0 and 0.4 Ma or transitory reheating to 300-350??C at about 0.4-0.6 Ma. Subsequent rapid cooling to below 260??C between 0.4 and 0.2 Ma is in agreement with previous proposals that vapor-dominated conditions were initiated within the hydrothermal system at this time. Heat flow calculations constrained with K-feldspar thermal histories and the present elevated regional heat flow anomaly demonstrate that appreciable heat input from sources external to the known Geysers plutonic complex is required to maintain the geothermal system. This requirement is satisfied by either a large, underlying, convecting magma chamber (now solidified) emplaced at 1.2 Ma or episodic intrusion of smaller bodies from 1.2 to 0.6 Ma.
A Geothermal GIS for Nevada: Defining Regional Controls and Favorable Exploration Terrains for Extensional Geothermal Systems

USGS Publications Warehouse

Coolbaugh, M.F.; Taranik, J.V.; Raines, G.L.; Shevenell, L.A.; Sawatzky, D.L.; Bedell, R.; Minor, T.B.

2002-01-01

Spatial analysis with a GIS was used to evaluate geothermal systems in Nevada using digital maps of geology, heat flow, young faults, young volcanism, depth to groundwater, groundwater geochemistry, earthquakes, and gravity. High-temperature (>160??C) extensional geothermal systems are preferentially associated with northeast-striking late Pleistocene and younger faults, caused by crustal extension, which in most of Nevada is currently oriented northwesterly (as measured by GPS). The distribution of sparse young (160??C) geothermal systems in Nevada are more likely to occur in areas where the groundwater table is shallow (<30m). Undiscovered geothermal systems may occur where groundwater levels are deeper and hot springs do not issue at the surface. A logistic regression exploration model was developed for geothermal systems, using young faults, young volcanics, positive gravity anomalies, and earthquakes to predict areas where deeper groundwater tables are most likely to conceal geothermal systems.
Geothermal systems

NASA Technical Reports Server (NTRS)

Mohl, C.

1978-01-01

Several tasks of JPL related to geothermal energy are discussed. The major task is the procurement and test and evaluation of a helical screw drive (wellhead unit). A general review of geothermal energy systems is given. The presentation focuses attention on geothermal reservoirs in California, with graphs and charts to support the discussion. Included are discussions on cost analysis, systems maintenance, and a comparison of geothermal and conventional heating and cooling systems.
Geothermal Coproduction and Hybrid Systems | Geothermal Technologies | NREL

Science.gov Websites

systems. Geothermal and Oil and Gas NREL experts are working to find ways to effectively use renewable resources in combination with fossil energy. Geothermal and oil and gas hybrid systems make use of wells already drilled by oil and gas developers. Using coproduced geothermal fluids for power production from
Reservoir Changes Derived from Seismic Observations at The Geysers Geothermal Field, CA, USA

NASA Astrophysics Data System (ADS)

Gritto, R.; Jarpre, S.

2012-04-01

Induced seismicity associated with the exploitation of geothermal fields is used as a tool to characterize and delineate changes associated with injection and production of fluids from the reservoir. At the same time public concern of felt seismicity has led to objections against the operation of geothermal reservoirs in close proximity to population centers. Production at the EGS sites in Basel (Switzerland) was stopped after renewed seismicity caused concern and objection from the public in the city. Operations in other geothermal reservoirs had to be scaled back or interrupted due to an unexpected increase in seismicity (Soultz-sous-forêt, France, Berlín, El Salvador). As a consequence of these concerns and in order to optimize the use of induced seismicity for reservoir engineering purposes, it becomes imperative to understand the relationship between seismic events and stress changes in the reservoir. We will address seismicity trends at The Geysers Geothermal Reservoir, CA USA, to understand the role of historical seismicity associated with past injection of water and/or production of steam. Our analysis makes use of a comprehensive database of earthquakes and associated phase arrivals from 2004 to 2011. A high-precision sub-set of the earthquake data was selected to analyze temporal changes in seismic velocities and Vp/Vs-ratio throughout the whole reservoir. We find relatively low Vp/Vs values in 2004 suggestive of a vapor dominated reservoir. With passing time, however, the observed temporal increase in Vp/Vs, coupled with a decrease in P- and S-wave velocities suggests the presence of fluid-filled fractured rock. Considering the start of a continuous water injection project in 2004, it can be concluded that the fluid saturation of the reservoir has successfully recovered. Preliminary results of 3-D velocity inversions of seismic data appear to corroborate earlier findings that the lowest Vp/Vs estimates are observed in the center of the reservoir. Vertical depth-sections indicate that these low values are co-located with production zones and production related seismicity. In contrast, the highest Vp/Vs estimates are co-located with injection zones and their associated seismicity.
California's geothermal resource potential

NASA Technical Reports Server (NTRS)

Leibowitz, L. P.

1978-01-01

According to a U.S. Geological Survey estimate, recoverable hydrothermal energy in California may amount to 19,000 MW of electric power for a 30-year period. At present, a geothermal installation in the Geysers region of the state provides 502 MWe of capacity; an additional 1500 MWe of electric generating capacity is scheduled to be in operation in geothermal fields by 1985. In addition to hydrothermal energy sources, hot-igneous and conduction-dominated resources are under investigation for possible development. Land-use conflicts, environmental concerns and lack of risk capital may limit this development.
An Embedded 3D Fracture Modeling Approach for Simulating Fracture-Dominated Fluid Flow and Heat Transfer in Geothermal Reservoirs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Johnston, Henry; Wang, Cong; Winterfeld, Philip

An efficient modeling approach is described for incorporating arbitrary 3D, discrete fractures, such as hydraulic fractures or faults, into modeling fracture-dominated fluid flow and heat transfer in fractured geothermal reservoirs. This technique allows 3D discrete fractures to be discretized independently from surrounding rock volume and inserted explicitly into a primary fracture/matrix grid, generated without including 3D discrete fractures in prior. An effective computational algorithm is developed to discretize these 3D discrete fractures and construct local connections between 3D fractures and fracture/matrix grid blocks of representing the surrounding rock volume. The constructed gridding information on 3D fractures is then added tomore » the primary grid. This embedded fracture modeling approach can be directly implemented into a developed geothermal reservoir simulator via the integral finite difference (IFD) method or with TOUGH2 technology This embedded fracture modeling approach is very promising and computationally efficient to handle realistic 3D discrete fractures with complicated geometries, connections, and spatial distributions. Compared with other fracture modeling approaches, it avoids cumbersome 3D unstructured, local refining procedures, and increases computational efficiency by simplifying Jacobian matrix size and sparsity, while keeps sufficient accuracy. Several numeral simulations are present to demonstrate the utility and robustness of the proposed technique. Our numerical experiments show that this approach captures all the key patterns about fluid flow and heat transfer dominated by fractures in these cases. Thus, this approach is readily available to simulation of fractured geothermal reservoirs with both artificial and natural fractures.« less
Demonstration of a Variable Phase Turbine Power System for Low Temperature Geothermal Resources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hays, Lance G

2014-07-07

A variable phase turbine assembly will be designed and manufactured having a turbine, operable with transcritical, two-phase or vapor flow, and a generator – on the same shaft supported by process lubricated bearings. The assembly will be hermetically sealed and the generator cooled by the refrigerant. A compact plate-fin heat exchanger or tube and shell heat exchanger will be used to transfer heat from the geothermal fluid to the refrigerant. The demonstration turbine will be operated separately with two-phase flow and with vapor flow to demonstrate performance and applicability to the entire range of low temperature geothermal resources. The vapormore » leaving the turbine is condensed in a plate-fin refrigerant condenser. The heat exchanger, variable phase turbine assembly and condenser are all mounted on single skids to enable factory assembly and checkout and minimize installation costs. The system will be demonstrated using low temperature (237F) well flow from an existing large geothermal field. The net power generated, 1 megawatt, will be fed into the existing power system at the demonstration site. The system will demonstrate reliable generation of inexpensive power from low temperature resources. The system will be designed for mass manufacturing and factory assembly and should cost less than $1,200/kWe installed, when manufactured in large quantities. The estimated cost of power for 300F resources is predicted to be less than 5 cents/kWh. This should enable a substantial increase in power generated from low temperature geothermal resources.« less

Investment and operating costs of binary cycle geothermal power plants

NASA Technical Reports Server (NTRS)

Holt, B.; Brugman, J.

1974-01-01

Typical investment and operating costs for geothermal power plants employing binary cycle technology and utilizing the heat energy in liquid-dominated reservoirs are discussed. These costs are developed as a function of reservoir temperature. The factors involved in optimizing plant design are discussed. A relationship between the value of electrical energy and the value of the heat energy in the reservoir is suggested.
Prediction and discovery of new geothermal resources in the Great Basin: Multiple evidence of a large undiscovered resource base

USGS Publications Warehouse

Coolbaugh, M.F.; Raines, G.L.; Zehner, R.E.; Shevenell, L.; Williams, C.F.

2006-01-01

Geothermal potential maps by themselves cannot directly be used to estimate undiscovered resources. To address the undiscovered resource base in the Great Basin, a new and relatively quantitative methodology is presented. The methodology involves three steps, the first being the construction of a data-driven probabilistic model of the location of known geothermal systems using weights of evidence. The second step is the construction of a degree-of-exploration model. This degree-of-exploration model uses expert judgment in a fuzzy logic context to estimate how well each spot in the state has been explored, using as constraints digital maps of the depth to the water table, presence of the carbonate aquifer, and the location, depth, and type of drill-holes. Finally, the exploration model and the data-driven occurrence model are combined together quantitatively using area-weighted modifications to the weights-of-evidence equations. Using this methodology in the state of Nevada, the number of undiscovered geothermal systems with reservoir temperatures ???100??C is estimated at 157, which is 3.2 times greater than the 69 known systems. Currently, nine of the 69 known systems are producing electricity. If it is conservatively assumed that an additional nine for a total of 18 of the known systems will eventually produce electricity, then the model predicts 59 known and undiscovered geothermal systems are capable of producing electricity under current economic conditions in the state, a figure that is more than six times higher than the current number. Many additional geothermal systems could potentially become economic under improved economic conditions or with improved methods of reservoir stimulation (Enhanced Geothermal Systems).This large predicted geothermal resource base appears corroborated by recent grass-roots geothermal discoveries in the state of Nevada. At least two and possibly three newly recognized geothermal systems with estimated reservoir temperatures ???150??C have been identified on the Pyramid Lake Paiute Reservation in west-central Nevada. Evidence of three blind geothermal systems has recently been uncovered near the borate-bearing playas at Rhodes, Teels, and Columbus Marshes in southwestern Nevada. Recent gold exploration drilling has resulted in at least four new geothermal discoveries, including the McGinness Hills geothermal system with an estimated reservoir temperature of roughly 200??C. All of this evidence suggests that the potential for expansion of geothermal power production in Nevada is significant.
Radon and temperature as tracer of geothermal flow system: application to Arxan geothermal system, Northeastern China

NASA Astrophysics Data System (ADS)

Gu, X.; Shao, J.; Cui, Y.

2017-12-01

In this work, hydrogeological and hydrochemical investigations were applied to explain geothermal system factors controlling groundwater mineralization in Arxan geothermal system, Northeastern China. Geothermal water samples were collected from different locations (thermal baths and wells). Radon concentrations of water samples representing different water types and depths were controlled using RAD7. In addition to radon concentration, physical parameters such as temperature (T), pH, electrical conductivity (EC) and TDS were measured in situ, while major ions were analyzed in laboratory. Temperature spatial variability in the study area was described using kriging interpolation method. Hydrochemical analysis and thermal parameters suggest two distinct hydrogeological systems. The first type was dominated by a moderate temperature (25 41°C) with a chemical facies Na-HCO3, which characterizes Jurassic deep water. The second water type was characterized by Ca.Na-HCO3 type with a temperature <25 °C and represents the shallow aquifer. Superficial aquifer displays higher radon concentration (37 to 130 Bq/L), while deep groundwater from Jurassic aquifer shows relatively a low radon concentration (6 to 57.4 Bq/L). Seasonal and geographical variations of radon give insight into the processes controlling radon activities in the Arxan groundwater. Radon concentrations along with spatial distribution of water temperature reveal the existence of vertical communication between shallow aquifer and deep Jurassic aquifer through vertical faults and fractures system, the emanation of radon from thermal water and groundwater is controlled by the geological structure of the area. Furthermore, the knowledge and conclusion demonstrates that combined use of radon and temperature as tracers can give insight into the characteristics of geological structure and geothermal flow system.
Third workshop on geothermal reservoir engineering: Proceedings

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ramey, H.J. Jr.; Kruger, P.

1977-12-15

The Third Workshop on Geothermal Reservoir Engineering convened at Stanford University on December 14, 1977, with 104 attendees from six nations. In keeping with the recommendations expressed by the participants at the Second Workshop, the format of the Workshop was retained, with three days of technical sessions devoted to reservoir physics, well and reservoir testing, field development, and mathematical modeling of geothermal reservoirs. The program presented 33 technical papers, summaries of which are included in these Proceedings. Although the format of the Workshop has remained constant, it is clear from a perusal of the Table of Contents that considerable advancesmore » have occurred in all phases of geothermal reservoir engineering over the past three years. Greater understanding of reservoir physics and mathematical representations of vapor-dominated and liquid-dominated reservoirs are evident; new techniques for their analysis are being developed, and significant field data from a number of newer reservoirs are analyzed. The objectives of these workshops have been to bring together researchers active in the various physical and mathematical disciplines comprising the field of geothermal reservoir engineering, to give the participants a forum for review of progress and exchange of new ideas in this rapidly developing field, and to summarize the effective state of the art of geothermal reservoir engineering in a form readily useful to the many government and private agencies involved in the development of geothermal energy. To these objectives, the Third Workshop and these Proceedings have been successfully directed. Several important events in this field have occurred since the Second Workshop in December 1976. The first among these was the incorporation of the Energy Research and Development Administration (ERDA) into the newly formed Department of Energy (DOE) which continues as the leading Federal agency in geothermal reservoir engineering research. The Third Workshop under the Stanford Geothermal Program was supported by a grant from DOE through a subcontract with the Lawrence Berkeley Laboratory of the University of California. A second significant event was the first conference under the ERDA (DOE)-ENEL cooperative program where many of the results of well testing in both nations were discussed. The Proceedings of that conference should be an important contribution to the literature. These Proceedings of the Third Workshop should also make an important contribution to the literature on geothermal reservoir engineering. Much of the data presented at the Workshop were given for the first time, and full technical papers on these subjects will appear in the professional journals. The results of these studies will assist markedly in developing the research programs to be supported by the Federal agencies, and in reducing the costs of research for individual developers and utilities. It is expected that future workshops of the Stanford Geothermal Program will be as successful as this third one. Planning and execution of the Workshop... [see file; ljd, 10/3/2005] The Program Committee recommended two novel sessions for the Third Workshop, both of which were included in the program. The first was the three overviews given at the Workshop by George Pinder (Princeton) on the Academic aspect, James Bresee (DOE-DGE) on the Government aspect, and Charles Morris (Phillips Petroleum) on the Industry aspect. These constituted the invited slate of presentations from the several sectors of the geothermal community. The Program Committee acknowledges their contributions with gratitude. Recognition of the importance of reservoir assurance in opting for geothermal resources as an alternate energy source for electric energy generation resulted in a Panel Session on Various Definitions of Geothermal Reservoirs. Special acknowledgments are offered to Jack Howard and Werner Schwarz (LBL) and to Jack Howard as moderator; to the panelists: James Leigh (Lloyd's Bank of California), Stephen Lipman (Union Oil), Mark Mathisen (PG&E), Patrick Muffler (USGS-MP), and Mark Silverman (DOE-SAN); and to the rapporteurs: George Frye (Aminoil), Vasel Roberts (Electrical Power Research Institute), and Alexander Graf (LBL), whose Valuable summaries are included in the Proceedings. Special thanks are also due Roland Horne, Visiting Professor from New Zealand and Program Manager of the Stanford Geothermal Program, for his efforts with the Program graduate students in conducting the Workshop. Further thanks go to Marion Wachtel, who in spite of tremendous personal hardship, administered the Workshop and prepared the Proceedings in a timely and professional manner. Professor Ramey and I also express our appreciation to the Department of Energy, whose financial support of the Workshop made possible the program and these Proceedings. Paul Kruger Stanford University December 31, 1977« less
Geothermal Power Supply Systems around the World and in Russia: State of the Art and Future Prospects

NASA Astrophysics Data System (ADS)

Butuzov, V. A.; Amerkhanov, R. A.; Grigorash, O. V.

2018-05-01

Solar and geothermal energy systems are shown to have received the widest use among all kinds of renewable sources of energy for heat supply purposes around the world. The power capacities and amounts of thermal energy generated by solar and geothermal heat supply systems around the world are presented by way of comparison. The thermal power capacity of solar heat supply systems installed around the world as of 2015 totaled 268.1 GW, and the thermal energy generated by them amounted to 225 TW h/year. The thermal power capacity of geothermal heat supply systems installed around the world totaled 70.3 GW, and the thermal energy generated by them amounted to 163 TW h/year. Information on the geothermal heat supply systems in the leading countries around the world based on the data reported at the World Geothermal Congress held in 2015 is presented. It is shown that China, with the installed thermal power capacities of its geothermal heat supply stations totaling 17.87 GW and the amount of thermal energy generated per annum equal to 48.435 TW h/year, is the world's leader in this respect. The structures of geothermal heat supply systems by the kinds of heat consumption used around the world are presented. The systems equipped with geothermal heat pumps accounted for 70.95% in the total installed capacity and for 55.3% in the total amount of generated heat. For systems that do not use heat pumps, those serving for pools account for the largest share amounting to 44.74% in installed capacity and to 45.43% in generated heat. A total of 2218 geothermal wells with the total length equal to 9534 km (with 38.7% of them for heat supply purposes) were drilled in 42 countries in the period from 2010 to 2014. In Russia, geothermal heat supply systems are in operation mainly in Dagestan, in Krasnodar krai, and in Kamchatka. The majority of these systems have been made without breaking the stream after the well outlet. A cyclic control arrangement is also used. The combined geothermal and solar heat supply system with an installed thermal power capacity of 5 MW that is in operation in the Rozovyi settlement, Krasnodar krai, is described. In the summer time, the solar installation with a capacity of 115 kW is used for supplying hot water to residential houses and for restoring the geothermal well pore pressure. The basic process circuit and characteristics of the geothermal heat supply system with the installed thermal power capacity of 8.7 MW operating in the Khankala settlement, the city of Groznyi, are given. The specific feature of this system is that the spent geothermal heat carrier is reinjected into a specially drilled inclined well. Advanced geothermal heat supply technologies involving reinjection of the spent geothermal heat carrier, combination with binary power units, use of heat pumps for recovering the spent heat carrier, and protection of equipment from corrosion and deposits are proposed.
The hydrothermal evolution of the Kawerau geothermal system, New Zealand

NASA Astrophysics Data System (ADS)

Milicich, S. D.; Chambefort, I.; Wilson, C. J. N.; Charlier, B. L. A.; Tepley, F. J.

2018-03-01

Hydrothermal alteration zoning and processes provide insights into the evolution of heat source(s) and fluid compositions associated with geothermal systems. Traditional petrological techniques, combined with hydrothermal alteration studies, stable isotope analyses and geochronology can resolve the nature of the fluids involved in hydrothermal processes and their changes through time. We report here new findings along with previous unpublished works on alteration patterns, fluid inclusion measurements and stable isotope data to provide insights into the thermal and chemical evolution of the Kawerau geothermal system, New Zealand. These data indicate the presence of two hydrothermal events that can be coupled with chronological data. The earlier period of hydrothermal activity was initiated at 400 ka, with the heat driving the hydrothermal system inferred to be from the magmatic system that gave rise to rhyolite lavas and sills of the Caxton Formation. Isotopic data fingerprint fluids attributed to this event as meteoric, indicating that the magma primarily served as a heat source driving fluid circulation, and was not releasing magmatic fluids in sufficient quantity to affect the rock mineralogy and thus inferred fluid compositions. The modern Kawerau system was initiated at 16 ka with hydrothermal eruptions linked to shallow intrusion of magma at the onset of activity that gave rise to the Putauaki andesite cone. Likely associated with this later event was a pulse of magmatic CO2, resulting in large-scale deposition of hydrothermal calcite enriched in 18O. Meteoric water-dominated fluids subsequently overwhelmed the magmatic fluids associated with this 18O-rich signature, and both the fluid inclusion microthermometry and stable isotope data reflect a change to the present-day fluid chemistry of low salinity, meteoric-dominated waters.
Materials selection guidelines for geothermal energy utilization systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ellis, P.F. II; Conover, M.F.

1981-01-01

This manual includes geothermal fluid chemistry, corrosion test data, and materials operating experience. Systems using geothermal energy in El Salvador, Iceland, Italy, Japan, Mexico, New Zealand, and the United States are described. The manual provides materials selection guidelines for surface equipment of future geothermal energy systems. The key chemical species that are significant in determining corrosiveness of geothermal fluids are identified. The utilization modes of geothermal energy are defined as well as the various physical fluid parameters that affect corrosiveness. Both detailed and summarized results of materials performance tests and applicable operating experiences from forty sites throughout the world aremore » presented. The application of various non-metal materials in geothermal environments are discussed. Included in appendices are: corrosion behavior of specific alloy classes in geothermal fluids, corrosion in seawater desalination plants, worldwide geothermal power production, DOE-sponsored utilization projects, plant availability, relative costs of alloys, and composition of alloys. (MHR)« less
Microbial Diversity, Distribution and Insight into Their Role in S, Fe and N Biogeochemical Cycling in the Hot Springs at Tengchong Geothermal Fields, Southwest China

NASA Astrophysics Data System (ADS)

Li, J.; Peng, X.; Zhang, L.

2014-12-01

Ten sediment samples collected from one acidic and three alkaline high temperature hot springs at Tengchong terrestrial geothermal field, Southwest China, were examined by the mineralogical, geochemical, and molecular biological techniques. The mineralogical and geochemical analyses suggested that these hot springs contain relative high concentrations of S, Fe and N chemical species. Specifically, the acidic hot spring was rich in Fe2+, SO42- and NH4+, while the alkaline hot springs were high in NO3-, H2S and S2O3-. Analyses of 16S rRNA sequences showed their bacterial communities were dominated by Aquificae, Cyanobacteria, Deinococci-Thermus, Firmicutes, Proteobacteria, and Thermodesulfobacteria, while the archeal clone libraries were dominated by Desulfurococcales, Sulfolobales, and Thermoproteales. Among them, the potential S-, N- and Fe-related oxidizing and reducing prokaryote were presenting as a relative high proportion but with a great difference in diversity and metabolic approaches of each sample. These findings provide some significant implications for the microbial function in element biogeochemical cycles within the Tengchong geothermal environments: i). the distinct differences in abundance and diversity of microbial communities of geothermal sediments were related to in situ different physicochemical conditions; ii). the S-, N- and Fe-related prokaryote would take advantage of the strong chemical disequilibria in the hot springs; iii). in return, their metabolic activities can promote the transformation of S, Fe and N chemical species, thus founded the bases of biogeochemical cycles in the terrestrial geothermal environments.
Formation evaluation in liquid-dominated geothermal reservoirs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ershaghi, I.; Dougherty, E.E.; Handy, L.L.

1981-04-01

Studies relative to some formation evaluation aspects of geothermal reservoirs are reported. The particular reservoirs considered were the liquid dominated type with a lithology of the sedimentary nature. Specific problems of interest included the resistivity behavior of brines and rocks at elevated temperatures and studies on the feasibility of using the well log resistivity data to obtain estimates of reservoir permeability. Several papers summarizing the results of these studies were presented at various technical meetings for rapid dissemination of the results to potential users. These papers together with a summary of data most recently generated are included. A brief reviewmore » of the research findings precedes the technical papers. Separate abstracts were prepared for four papers. Five papers were abstracted previously for EDB.« less
Geothermal Systems of the Great Basin and U.S. Geological Survey Plans for a Regional Resource Assessment

USGS Publications Warehouse

Williams, C.F.

2002-01-01

Based on current projections, the United States faces the need to increase its electrical power generating capacity by 40% (approximately 300,000 Megawatts-electrical or MWe) over the next 20 years (Energy Information Administration, EIA - Department of Energy). A critical question for the near future is the extent to which geothermal resources can contribute to this increasing demand for electricity. Geothermal energy constitutes one of the nation's largest sources of renewable and environmentally benign electrical power, yet the installed capacity of 2860 MWe falls far short of estimated geothermal resources. This is particularly true for the Great Basin region of the western United States, which has an installed capacity of about 500 MWe, much lower than the 7500 MWe resource estimated by the U.S. Geological Survey (USGS) in the late 1970s. The reasons for the limited development of geothermal power are varied, but political, economic and technological developments suggest the time is ripe for a new assessment effort. Technologies for power production from geothermal systems and scientific understanding of geothermal resource occurrence have improved dramatically in recent years. The primary challenges facing geothermal resource studies are (1) understanding the thermal, chemical and mechanical processes that lead to the colocation of high temperatures and high permeabilities necessary for the formation of geothermal systems and (2) developing improved techniques for locating, characterizing and exploiting these systems. Starting in the fall of 2002, the USGS will begin work with institutions funded by the Department of Energy's (DOE) Geothermal Research Program to investigate the nature and extent of geothermal systems in the Great Basin and to produce an updated assessment of available geothermal resources.
Geothermal GIS coverage of the Great Basin, USA: Defining regional controls and favorable exploration terrains

USGS Publications Warehouse

Coolbaugh, M.F.; Sawatzky, D.L.; Oppliger, G.L.; Minor, T.B.; Raines, G.L.; Shevenell, L.; Blewitt, G.; Louie, J.N.

2003-01-01

A geographic information system (GIS) of geothermal resources, built last year for the state of Nevada, is being expanded to cover the Great Basin, USA. Data from that GIS is being made available to industry, other researchers, and the public via a web site at the Great Basin Center for Geothermal Energy, Reno, Nevada. That web site features a search engine, supports ArcExplorer?? for on-line map construction, and provides downloadable data layers in several formats. Though data collection continues, preliminary analysis has begun. Contour maps of geothermal temperatures, constructed using geothermometer temperatures calculated from a Great Basin geochemical database compiled by the Geo-Heat Center, reveal distinctive trends and patterns. As expected, magmatic-type and extensional-type geothermal systems have profoundly different associations, with magmatic-type systems following major tectonic boundaries, and extensional-type systems associating with regionally high heat flow, thin crust, active faulting, and high extensional strain rates. As described by earlier researchers, including Rowen and Wetlaufer (1981) and Koenig and McNitt (1983), high-temperature (> 100??C) geothermal systems appear to follow regional northeast trends, most conspicuously including the Humboldt structural zone in Nevada, the "Black Rock-Alvord Desert" trend in Oregon and Nevada, and the "Newcastle-Roosevelt" trend in Utah and Nevada. Weights-of-evidence analyses confirm a preference of high-temperature geothermal systems for young northeast-trending faults, but the distribution of geothermal systems correlates even better with high rates of crustal extension, as measured from global positioning system (GPS) stations in Nevada. A predictive map of geothermal potential based only on areas of high extensional strain rates and high heat flux does an excellent job of regionally predicting the location of most known geothermal systems in Nevada, and may prove useful in identifying blind systems.
Qrtzgeotherm: An ActiveX component for the quartz solubility geothermometer

NASA Astrophysics Data System (ADS)

Verma, Mahendra P.

2008-12-01

An ActiveX component, QrtzGeotherm, to calculate temperature and vapor fraction in a geothermal reservoir using quartz solubility geothermometry was written in Visual Basic 6.0. Four quartz solubility equations along the liquid-vapor saturation curve: (i) a quadratic equation of 1/ T and pressure, (ii) a linear equation relating log SiO 2 to the inverse of absolute temperature ( T), (iii) a polynomial of T including logarithmic terms and (iv) temperature as a polynomial of SiO 2 including logarithmic terms are programmed. The QrtzGeotherm has input parameters: (i) HRes—the reservoir enthalpy (kJ/kg), (ii) SiO2TD—silica concentration in total discharge (ppm), (iii) GeoEq—number of quartz solubility equation and (iv) TempGuess—a guess value of the reservoir temperature (°C). The reservoir enthalpy Hres is assumed to be the same as the total discharge enthalpy HR. The output parameters are (i) TempRes—reservoir temperature (°C) and (ii) VapRes—reservoir vapor fraction. The first step is to calculate the total discharge concentration of silica SiO2TD from the concentration of silica SiO2Col of separated water, sampled after N-separations of vapor and water. To use QrtzGeotherm in MS-Excel, three functions SiO2TD, GeoResTemp and GeoResVap for an N-stage separation of geothermal reservoir fluid are written in Visual Basic for Application (VBA). Similarly, a demonstration program, QrtzGeothrm, is written in Visual Basic 6.0.
Improving Geothermal Heat Pump Air Conditioning Efficiency with Wintertime Cooling using Seasonal Thermal Energy Storage (STES). Application Manual

DTIC Science & Technology

2016-11-01

Defense. Reference herein to any specific commercial product , process, or service by trade name, trademark, manufacturer, or otherwise, does not...1 1.3 Cooling-Dominated Buildings and MCAS Beaufort Case Study 4 1.4 Potential Approach for Mitigating Heat Buildup -- Hybrid Geothermal Heat...the ground through another well. This type of system can be very effective, but it requires access to a productive aquifer with associated
Life Cycle Water Consumption and Water Resource Assessment for Utility-Scale Geothermal Systems: An In-Depth Analysis of Historical and Forthcoming EGS Projects

DOE Data Explorer

Schroeder, Jenna N.

2013-08-31

This report is the third in a series of reports sponsored by the U.S. Department of Energy Geothermal Technologies Program in which a range of water-related issues surrounding geothermal power production are evaluated. The first report made an initial attempt at quantifying the life cycle fresh water requirements of geothermal power-generating systems and explored operational and environmental concerns related to the geochemical composition of geothermal fluids. The initial analysis of life cycle fresh water consumption of geothermal power-generating systems identified that operational water requirements consumed the vast majority of water across the life cycle. However, it relied upon limited operational water consumption data and did not account for belowground operational losses for enhanced geothermal systems (EGSs). A second report presented an initial assessment of fresh water demand for future growth in utility-scale geothermal power generation. The current analysis builds upon this work to improve life cycle fresh water consumption estimates and incorporates regional water availability into the resource assessment to improve the identification of areas where future growth in geothermal electricity generation may encounter water challenges.
The Significance of Acid Alteration in the Los Humeros High-Temperature Geothermal Field, Puebla, Mexico.

NASA Astrophysics Data System (ADS)

Elders, W. A.; Izquierdo, G.

2014-12-01

The Los Humeros geothermal field is a high-enthalpy hydrothermal system with more than 40 drilled deep wells, mostly producing high steam fractions at > 300oC. However, although it has a large resource potential, low permeability and corrosive acid fluids have hampered development so that it currently has an installed electrical generating capacity of only 40 MWe. The widespread production of low pH fluids from the reservoir is inconsistent with the marked absence in the reservoir rocks of hydrothermal minerals typical of acid alteration. Instead the hydrothermal alteration observed is typical of that due to neutral to alkaline pH waters reacting with the volcanic rocks of the production zones. Thus it appears that since the reservoir has recently suffered a marked drop in fluid pressure and is in process of transitioning from being water-dominated to being vapor-dominated. However sparse examples of acid leaching are observed locally at depths of about 2 km in the form of bleached, intensely silicified zones, in low permeability and very hot (>350oC) parts of reservoir. Although these leached rocks retain their primary volcanic and pyroclastic textures, they are altered almost entirely to microcrystalline quartz, with some relict pseudomorphs of plagioclase phenocrysts and traces of earlier-formed hydrothermal chlorite and pyrite. These acid-altered zones are usually only some tens of meters thick and deeper rocks lack such silicification. The acid fluids responsible for their formation could either be magmatic volatiles, or could be formed during production (e.g. reaction of water and salts forming hydrogen chloride by hydrolysis at high temperatures). The very high boron content of the fluids produced by the Los Humeros wells suggests that their ultimate source is most likely magmatic gases. However, these acid gases did not react widely with the rocks. We suggest that the silicified zones are forming locally where colder descending waters are encountering superheated (or possibly supercritical) steam containing acid gas, thus forming low pH liquids that react with the reservoir rocks.
Federal Geothermal Research Program Update - Fiscal Year 2004

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patrick Laney

2005-03-01

The Department of Energy (DOE) and its predecessors have conducted research and development (R&D) in geothermal energy since 1971. The Geothermal Technologies Program (GTP) works in partnership with industry to establish geothermal energy as an economically competitive contributor to the U.S. energy supply. Geothermal energy production, a $1.5 billion a year industry, generates electricity or provides heat for direct use applications. The technologies developed by the Geothermal Technologies Program will provide the Nation with new sources of electricity that are highly reliable and cost competitive and do not add to America's air pollution or the emission of greenhouse gases. Geothermalmore » electricity generation is not subject to fuel price volatility and supply disruptions from changes in global energy markets. Geothermal energy systems use a domestic and renewable source of energy. The Geothermal Technologies Program develops innovative technologies to find, access, and use the Nation's geothermal resources. These efforts include emphasis on Enhanced Geothermal Systems (EGS) with continued R&D on geophysical and geochemical exploration technologies, improved drilling systems, and more efficient heat exchangers and condensers. The Geothermal Technologies Program is balanced between short-term goals of greater interest to industry, and long-term goals of importance to national energy interests. The program's research and development activities are expected to increase the number of new domestic geothermal fields, increase the success rate of geothermal well drilling, and reduce the costs of constructing and operating geothermal power plants. These improvements will increase the quantity of economically viable geothermal resources, leading in turn to an increased number of geothermal power facilities serving more energy demand. These new geothermal projects will take advantage of geothermal resources in locations where development is not currently possible or economical.« less
The role of the geothermal gradient in the emplacement and replenishment of ground ice on Mars

NASA Technical Reports Server (NTRS)

Clifford, Stephen M.

1993-01-01

Knowledge of the mechanisms by which ground ice is emplaced, removed, and potentially replenished, are critical to understanding the climatic and hydrologic behavior of water on Mars, as well as the morphologic evolution of its surface. Because of the strong temperature dependence of the saturated vapor pressure of H2O, the atmospheric emplacement or replenishment of ground ice is prohibited below the depth at which crustal temperatures begin to monotonically increase due to geothermal heating. In contrast, the emplacement and replenishment of ground ice from reservoirs of H2O residing deep within the crust can occur by at least three different thermally-driven processes, involving all three phases of water. In this regard, Clifford has discussed how the presence of a geothermal gradient as small as 15 K/km can give rise to a corresponding vapor pressure gradient sufficient to drive the vertical transport of 1 km of water from a reservoir of ground water at depth to the base of the cryosphere every 10(exp 6) - 10(exp 7) years. This abstract expands on this earlier treatment by considering the influence of thermal gradients on the transport of H2O at temperatures below the freezing point.
Federal Geothermal Research Program Update Fiscal Year 2004

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

2005-03-01

The Department of Energy (DOE) and its predecessors have conducted research and development (R&D) in geothermal energy since 1971. The Geothermal Technologies Program (GTP) works in partnership with industry to establish geothermal energy as an economically competitive contributor to the U.S. energy supply. Geothermal energy production, a $1.5 billion a year industry, generates electricity or provides heat for direct use applications. The technologies developed by the Geothermal Technologies Program will provide the Nation with new sources of electricity that are highly reliable and cost competitive and do not add to America's air pollution or the emission of greenhouse gases. Geothermalmore » electricity generation is not subject to fuel price volatility and supply disruptions from changes in global energy markets. Geothermal energy systems use a domestic and renewable source of energy. The Geothermal Technologies Program develops innovative technologies to find, access, and use the Nation's geothermal resources. These efforts include emphasis on Enhanced Geothermal Systems (EGS) with continued R&D on geophysical and geochemical exploration technologies, improved drilling systems, and more efficient heat exchangers and condensers. The Geothermal Technologies Program is balanced between short-term goals of greater interest to industry, and long-term goals of importance to national energy interests. The program's research and development activities are expected to increase the number of new domestic geothermal fields, increase the success rate of geothermal well drilling, and reduce the costs of constructing and operating geothermal power plants. These improvements will increase the quantity of economically viable geothermal resources, leading in turn to an increased number of geothermal power facilities serving more energy demand. These new geothermal projects will take advantage of geothermal resources in locations where development is not currently possible or economical.« less
Microbial community dynamics in Inferno Crater Lake, a thermally fluctuating geothermal spring.

PubMed

Ward, Laura; Taylor, Michael W; Power, Jean F; Scott, Bradley J; McDonald, Ian R; Stott, Matthew B

2017-05-01

Understanding how microbial communities respond and adjust to ecosystem perturbation is often difficult to interpret due to multiple and often simultaneous variations in observed conditions. In this research, we investigated the microbial community dynamics of Inferno Crater Lake, an acidic geothermal spring in New Zealand with a unique thermal cycle that varies between 30 and 80 °C over a period of 40-60 days. Using a combination of next-generation sequencing, geochemical analysis and quantitative PCR we found that the microbial community composition was predominantly chemolithotrophic and strongly associated with the thermal cycle. At temperatures >65 °C, the microbial community was dominated almost exclusively by sulphur-oxidising archaea (Sulfolobus-like spp.). By contrast, at mesophilic temperatures the community structure was more mixed, comprising both archaea and bacteria but dominated primarily by chemolithotrophic sulphur and hydrogen oxidisers. Multivariate analysis of physicochemical data confirmed that temperature was the only significant variable associated with community turnover. This research contributes to our understanding of microbial community dynamics in variable environments, using a naturally alternating system as a model and extends our limited knowledge of acidophile ecology in geothermal habitats.
An Estimate of Shallow, Low-Temperature Geothermal Resources of the United States: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mullane, Michelle; Gleason, Michael; McCabe, Kevin

Low-temperature geothermal resources in the United States potentially hold an enormous quantity of thermal energy, useful for direct use in residential, commercial and industrial applications such as space and water heating, greenhouse warming, pool heating, aquaculture, and low-temperature manufacturing processes. Several studies published over the past 40 years have provided assessments of the resource potential for multiple types of low-temperature geothermal systems (e.g. hydrothermal convection, hydrothermal conduction, and enhanced geothermal systems) with varying temperature ranges and depths. This paper provides a summary and additional analysis of these assessments of shallow (= 3 km), low-temperature (30-150 degrees C) geothermal resources inmore » the United States, suitable for use in direct-use applications. This analysis considers six types of geothermal systems, spanning both hydrothermal and enhanced geothermal systems (EGS). We outline the primary data sources and quantitative parameters used to describe resources in each of these categories, and present summary statistics of the total resources available. In sum, we find that low-temperature hydrothermal resources and EGS resources contain approximately 8 million and 800 million TWh of heat-in-place, respectively. In future work, these resource potential estimates will be used for modeling of the technical and market potential for direct-use geothermal applications for the U.S. Department of Energy's Geothermal Vision Study.« less

Geothermal Today: 2003 Geothermal Technologies Program Highlights (Revised)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

2004-05-01

This outreach publication highlights milestones and accomplishments of the DOE Geothermal Technologies Program for 2003. Included in this publication are discussions of geothermal fundamentals, enhanced geothermal systems, direct-use applications, geothermal potential in Idaho, coating technology, energy conversion R&D, and the GeoPowering the West initiative.
Corrosion engineering in the utilization of the Raft River geothermal resource

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, R.L.

1976-08-01

The economic impact of corrosion and the particular problems of corrosion in the utilization of geothermal energy resources are noted. Corrosion is defined and the parameters that control corrosion in geothermal systems are discussed. A general background of corrosion is presented in the context of the various forms of corrosion, in relation to the Raft River geothermal system. A basic reference for mechanical design engineers involved in the design of geothermal energy recovery systems is provided.
An evaluation of the deep reservoir conditions of the Bacon-Manito geothermal field, Philippines using well gas chemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

D'Amore, Franco; Maniquis-Buenviaje, Marinela; Solis, Ramonito P.

1993-01-28

Gas chemistry from 28 wells complement water chemistry and physical data in developing a reservoir model for the Bacon-Manito geothermal project (BMGP), Philippines. Reservoir temperature, T HSH, and steam fraction, y, are calculated or extrapolated from the grid defined by the Fischer-Tropsch (FT) and H 2-H 2S (HSH) gas equilibria reactions. A correction is made for H 2 that is lost due to preferential partitioning into the vapor phase and the reequilibration of H 2S after steam loss.
Young (<7 Ma) gold deposits and active geothermal systems of the Great Basin: Enigmas, questions, and exploration potential

USGS Publications Warehouse

Coolbaugh, Mark F.; Vikre, Peter G.; Faulds, James E.

2011-01-01

Young gold systems in the Great Basin (£ 7 Ma), though not as well studied as their older counterparts, comprise a rapidly growing and in some ways controversial group. The gold inventory for these systems has more than doubled in the last 5 years from roughly 370 tonnes (12 Moz) to 890 tonnes (29 Moz). Although these deposits are characterized by low grades, tonnages can be high and stripping ratios low, and they have been mined profitably, as exemplified by Florida Canyon and Hycroft. Active geothermal systems in the Great Basin also comprise a rapidly growing group, as evidenced by a number of recent discoveries of geothermal groundwater and a more than 50% increase in electricity production capacity from these systems in the last 5 years. Many young gold deposits are closely associated with active geothermal systems, suggesting that gold deposits may be forming today in the Great Basin. Measured or estimated geothermal reservoir temperatures commonly approach or exceed 200∞C, and other characteristics and processes (advanced argillic caps, hydrothermal eruption breccias) of these young deposits resemble those of nearby Tertiary precious metal deposits. Nonetheless, many young gold systems, especially in Nevada, are not associated with coeval igneous rocks. Similarly, almost all electricity-grade geothermal systems in Nevada are not associated with Quaternary silicic volcanic rocks, and have lower temperature gradients, lower 3He/4He ratios, and lower dissolved trace element concentrations than most magmatic-heated geothermal systems elsewhere in the world. The increasing economic significance of young gold deposits and active geothermal systems justifies more research to better understand their origins, particularly because in some aspects they remain enigmatic and controversial. Are young gold deposits in Nevada truly amagmatic, or have they received metal and fluid contributions from magmas deeper within the crust? Has gold in these deposits been remobilized from older gold mineralization? Current research is investigating these and other questions to improve our genetic understanding of these young gold systems, which in turn can lead to improved exploration targeting. The recent rapid growth in resources for both young gold deposits and geothermal systems underscores their underdeveloped exploration potential. Even though many young gold deposits exhibit relatively shallow hot-springs-style mineralization, their young age may preclude exposure by erosion. Uplift along active normal faults has exposed some deposits (e.g., Florida Canyon, Dixie Comstock, Wind Mountain), but in other areas, such as the Walker Lane, where strike-slip faulting is prevalent, the opportunities for exposure can be limited. Many active geothermal systems are also concealed below the surface in that hot springs or steam vents may be absent above areas of thermal groundwater.With sources of energy to support mine production becoming more problematic, the potential advantages of simultaneously exploring for young gold deposits and spatially associated geothermal systems are becoming more apparent. Exploration methods recently proven effective in geothermal exploration that can be adapted to gold exploration include temperature surveys, hyperspectral remote sensing, geophysical surveys, water analyses, and detailed mapping of geothermal-related features and related fault systems.
GEOTHERMAL ENVIRONMENTAL IMPACT ASSESSMENT: SUBSURFACE ENVIRONMENTAL ASSESSMENT FOR FOUR GEOTHERMAL SYSTEMS

EPA Science Inventory

This is the second in a series of reports concerning the environmental assessments of effluent extraction, energy conversion, and waste disposal in geothermal systems. This study involves the subsurface environmental impact of the Imperial Valley and The Geysers, California; Klam...
Improving geothermal power plants with a binary cycle

NASA Astrophysics Data System (ADS)

Tomarov, G. V.; Shipkov, A. A.; Sorokina, E. V.

2015-12-01

The recent development of binary geothermal technology is analyzed. General trends in the introduction of low-temperature geothermal sources are summarized. The use of single-phase low-temperature geothermal fluids in binary power plants proves possible and expedient. The benefits of power plants with a binary cycle in comparison with traditional systems are shown. The selection of the working fluid is considered, and the influence of the fluid's physicochemical properties on the design of the binary power plant is discussed. The design of binary power plants is based on the chemical composition and energy potential of the geothermal fluids and on the landscape and climatic conditions at the intended location. Experience in developing a prototype 2.5 MW Russian binary power unit at Pauzhetka geothermal power plant (Kamchatka) is outlined. Most binary systems are designed individually for a specific location. Means of improving the technology and equipment at binary geothermal power plants are identified. One option is the development of modular systems based on several binary systems that employ the heat from the working fluid at different temperatures.
An Estimate of Shallow, Low-Temperature Geothermal Resources of the United States

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mullane, Michelle; Gleason, Michael; Reber, Tim

Low-temperature geothermal resources in the United States potentially hold an enormous quantity of thermal energy, useful for direct use in residential, commercial and industrial applications such as space and water heating, greenhouse warming, pool heating, aquaculture, and low-temperature manufacturing processes. Several studies published over the past 40 years have provided assessments of the resource potential for multiple types of low-temperature geothermal systems (e.g. hydrothermal convection, hydrothermal conduction, and enhanced geothermal systems) with varying temperature ranges and depths. This paper provides a summary and additional analysis of these assessments of shallow (= 3 km), low-temperature (30-150 degrees C) geothermal resources inmore » the United States, suitable for use in direct-use applications. This analysis considers six types of geothermal systems, spanning both hydrothermal and enhanced geothermal systems (EGS). We outline the primary data sources and quantitative parameters used to describe resources in each of these categories, and present summary statistics of the total resources available. In sum, we find that low-temperature hydrothermal resources and EGS resources contain approximately 8 million and 800 million TWh of heat-in-place, respectively. In future work, these resource potential estimates will be used for modeling of the technical and market potential for direct-use geothermal applications for the U.S. Department of Energy's Geothermal Vision Study.« less
Gas and Isotope Geochemistry of 81 Steam Samples from Wells in The Geysers Geothermal Field, Sonoma and Lake Counties, California

USGS Publications Warehouse

Lowenstern, Jacob B.; Janik, Cathy J.; Fahlquist, Lynne; Johnson, Linda S.

1999-01-01

The Geysers geothermal field in northern California, with about 2000-MW electrical capacity, is the largest geothermal field in the world. Despite its importance as a resource and as an example of a vapor-dominated reservoir, very few complete geochemical analyses of the steam have been published (Allen and Day, 1927; Truesdell and others, 1987). This report presents data from 90 steam, gas, and condensate samples from wells in The Geysers geothermal field in northern California. Samples were collected between 1978 and 1991. Well attributes include sampling date, well name, location, total depth, and the wellhead temperature and pressure at which the sample was collected. Geochemical characteristics include the steam/gas ratio, composition of noncondensable gas (relative proportions of CO2, H2S, He, H2, O2, Ar, N2, CH4, and NH3), and isotopic values for deltaD and delta18O of H2O, delta13C of CO2, and delta34S of H2S. The compilation includes 81 analyses from 74 different production wells, 9 isotopic analyses of steam condensate pumped into injection wells, and 5 complete geochemical analyses on gases from surface fumaroles and bubbling pools. Most samples were collected as saturated steam and plot along the liquid-water/steam boiling curve. Steam-togas ratios are highest in the southeastern part of the geothermal field and lowest in the northwest, consistent with other studies. Wells in the Northwest Geysers are also enriched in N2/Ar, CO2 and CH4, deltaD, and delta18O. Well discharges from the Southeast Geysers are high in steam/gas and have isotopic compositions and N2/Ar ratios consistent with recharge by local meteoric waters. Samples from the Central Geysers show characteristics found in both the Southeast and Northwest Geysers. Gas and steam characteristics of well discharges from the Northwest Geysers are consistent with input of components from a high-temperature reservoir containing carbonrich gases derived from the host Franciscan rocks. Throughout the geothermal field, the carbon-isotopic composition of CO2 is consistent with derivation of carbon from Franciscan metasedimentary rocks. NH3 concentrations are high in most Geysers well fluids, and are 2-3 orders of magnitude greater than would be expected in a the gas phase exhibiting homogeneous equilibrium at normal reservoir temperatures and pressures. Evidently, NH3 is flushed from the Franciscan host rocks at a rate that exceeds the reaction rate for NH3 breakdown. Many wells show clear influence by fluids from reinjection wells where steam condensate has been pumped back into the geothermal reservoir. Six wells were resampled over the time period of this study. One of these six wells was strongly affected by a nearby injection well. Three of the six resampled wells showed some signs of decreasing liquid/ steam within the geothermal reservoir, consistent with 'drying out' of the reservoir due to steam withdrawal. However, two wells exhibited little change. Analyses of gases from five surface manifestations (fumaroles and bubbling pools) are roughly similar to the deeper geothermal samples in both chemical and isotopic composition, but are lower in soluble gases that dissolve in groundwater during transit toward the surface.
Diversity of Ktedonobacteria with Actinomycetes-Like Morphology in Terrestrial Environments

PubMed Central

Yabe, Shuhei; Sakai, Yasuteru; Abe, Keietsu; Yokota, Akira

2017-01-01

Bacteria with an actinomycetes-like morphology have recently been discovered, and the class Ktedonobacteria was created for these bacteria in the phylum Chloroflexi. They may prove to be a valuable resource with the potential to produce unprecedented secondary metabolites. However, our understanding of their diversity, richness, habitat, and ecological significance is very limited. We herein developed a 16S rRNA gene-targeted, Ktedonobacteria-specific primer and analyzed ktedonobacterial amplicons. We investigated abundance, diversity, and community structure in forest and garden soils, sand, bark, geothermal sediment, and compost. Forest soils had the highest diversity among the samples tested (1181–2934 operational taxonomic units [OTUs]; Chao 1 estimate, 2503–5613; Shannon index, 4.21–6.42). A phylogenetic analysis of representative OTUs revealed at least eight groups within unclassified Ktedonobacterales, expanding the known diversity of this order. Ktedonobacterial communities markedly varied among our samples. The common mesic environments (soil, sand, and bark) were dominated by diverse phylotypes within the eight groups. In contrast, compost and geothermal sediment samples were dominated by known ktedonobacterial families (Thermosporotrichaceae and Thermogemmatisporaceae, respectively). The relative abundance of Ktedonobacteria in the communities, based on universal primers, was ≤0.8%, but was 12.9% in the geothermal sediment. These results suggest that unknown diverse Ktedonobacteria inhabit common environments including forests, gardens, and sand at low abundances, as well as extreme environments such as geothermal areas. PMID:28321007
Geothermal activity supports islands of biodiversity in a hyper-arid, high-elevation landscape, Socompa Volcano, Puna de Atacama, Andes: A cultivation-independent molecular-phylogenetic view of soil microbial communities from an extreme

NASA Astrophysics Data System (ADS)

Costello, E.; Reed, S.; Sowell, P.; Halloy, S.; Schmidt, S.

2006-12-01

Socompa Volcano is a relatively young, unglaciated, 6051 m (19,852`) elevation stratovolcano that lies at the Chilean-Argentine border (24° 25`S, 68° 15`W) at the eastern edge of the Atacama Basin in the Arid Core of the Andes. A 1984 exploration revealed isolated mats of moss, liverwort, algae and lichen- dominated autotrophic communities associated with geothermal vents or warmspots near Socompa`s summit (Halloy, 1991). If extant, this system would present a unique opportunity to study life`s limits in a hyper-arid, high-elevation Mars-like landscape. Returning to Socompa in 2005, we encountered previously described warmspot "2" (Halloy, 1991) at 5824 m (19,107`) and found it partially disturbed by recent foot traffic. We collected warmspot-associated gas and soil samples, as well as other non-vent associated soils on Socompa. These soils were subjected to a battery of analyses, including cultivation-independent surveys of bacterial and eukaryotic small-subunit (SSU) ribosomal RNA (rRNA) gene sequences. Gas samples contained elevated CO2 and CH4 that, along with water vapor, vent directly from rocky "tubes" and percolate diffusely through the ground at the site. In general, Socompa soils were unvegetated, poorly sorted sands and gravels. Non-vent and vent-associated soils had pH 5.23 and 6.8, respectively. Non-vent and warm (25°C), disturbed (mat destroyed) vent-associated soils had no measurable moisture or nitrogen and 0.03% carbon (with SOM δ13C of -26‰). These soils also contained no measurable photosynthetic or photoprotective pigments and low enzyme activities. Conversely, cold (-5°C), undisturbed (but not overlain with dense mat) vent-associated soil had 10% water, 0.02% nitrogen and 0.25% carbon (C:N=13, SOM δ13C of -23.5‰). These soils had higher enzyme activities, contained chlorophyll a, and harbored a diverse array of algae, moss, liverwort, ascomycete, alveolate, and metazoan 18S rRNA sequences (~30 species). On the other hand, in the warm, disturbed vent-associated soil, 1 of only 4 observed eukaryotic species dominated (a cercomonad), and non-vent soil contained only 6 species and was dominated by fungi such as the basidiomycete yeast Cryptococcus. Bacterial diversity was high and significantly different among the three soils. Cyanobacterial sequences were only observed in the cold, undisturbed vent- associated soils. All soils produced colonies on soil extract agar at 0°C, but 10-100X more originated from the cold, undisturbed vent-associated soil. These results suggest that water vapor and possibly CO2, but not necessarily heat, may infiltrate soil across a wider area than previously thought on Socompa, and that these minimal inputs support a complex community whose parent populations may exist hundreds of kilometers away. However, we also note that non-vent associated soils from this cold, arid site are not completely "lifeless". Finally, we caution travelers to this area that physical disturbance can easily destroy these delicate, cryptic communities.
Geothermal Energy Potential in Western United States

ERIC Educational Resources Information Center

Pryde, Philip R.

1977-01-01

Reviews types of geothermal energy sources in the western states, including hot brine systems and dry steam systems. Conversion to electrical energy is a major potential use of geothermal energy, although it creates environmental disruptions such as noise, corrosion, and scaling of equipment. (AV)
Geophysical, geochemical, and geological investigations of the Dunes geothermal system, Imperial Valley, California

NASA Technical Reports Server (NTRS)

Elders, W. A.; Combs, J.; Coplen, T. B.; Kolesar, P.; Bird, D. K.

1974-01-01

The Dunes anomaly is a water-dominated geothermal system in the alluvium of the Salton Trough, lacking any surface expression. It was discovered by shallow-temperature gradient measurements. A 612-meter-deep test well encountered several temperature-gradient reversals, with a maximum of 105 C at 114 meters. The program involves surface geophysics, including electrical, gravity, and seismic methods, down-hole geophysics and petrophysics of core samples, isotopic and chemical studies of water samples, and petrological and geochemical studies of the cores and cuttings. The aim is (1) to determine the source and temperature history of the brines, (2) to understand the interaction between the brines and rocks, and (3) to determine the areal extent, nature, origin, and history of the geothermal system. These studies are designed to provide better definition of exploration targets for hidden geothermal anomalies and to contribute to improved techniques of exploration and resource assessment.
Coniform stromatolites from geothermal systems, North Island, New Zealand

USGS Publications Warehouse

Jones, Brian; Renaut, Robin W.; Rosen, Michael R.; Ansdell, Kevin M.

2002-01-01

Coniform stromatolites are found in several sites in the Tokaanu and Whakarewarewa geothermal areas of North Island, New Zealand. At Tokaanu, silicification of these stromatolites is taking place in Kirihoro, a shallow hot springfed pool. At Whakarewarewa, subfossil silicified coniform stromatolites are found on the floor of "Waikite Pool" on the discharge apron below Waikite Geyser, and in an old sinter succession at Te Anarata. The microbes in the coniform stromatolites from Tokaanu, Waikite Pool, and Te Anarata have been well preserved through rapid silicification. Nevertheless, subtle differences in the silicification style induced morphological variations that commonly mask or alter morphological features needed for identification of the microbes in terms of extant taxa. The coniform stromatolites in the New Zealand hotspring pools are distinctive because (1) they are formed of upward tapering (i.e., conical) columns, (2) neighboring columns commonly are linked by vertical sheets or bridges, (3) internally, they are formed of alternating high- and low-porosity laminae that have a conical vertical profile, and (4) Phormidium form more than 90% of the biota. As such, they are comparable to modern coniform mats and stromatolites found in the geothermal systems of Yellowstone National Park and ice-covered lakes in Antarctica. Formation of the coniform stromatolites is restricted to pools that are characterized by low current energy and a microflora that is dominated by Phormidium. These delicate and intricate stromatolites could not form in areas characterized by fast flowing water or a diverse microflora. Thus, it appears that the distribution of these distinctive stromatolites is controlled by biological constraints that are superimposed on environmental needs.
Discriminating Characteristics of Tectonic and Human-Induced Seismicity

NASA Astrophysics Data System (ADS)

Zaliapin, I. V.; Ben-Zion, Y.

2015-12-01

We analyze statistical features of background and clustered subpopulations of earthquakes in different regions in an effort to distinguish between human-induced and natural seismicity. Analysis of "end-member" areas known to be dominated by human-induced earthquakes (the Geyser geothermal field in northern California and TauTona gold mine in South Africa) and regular tectonic activity (the San Jacinto fault zone in southern California and Coso region excluding the Coso geothermal field in eastern central California) reveals several distinguishing characteristics. Induced seismicity is shown to have (i) higher rate of background events (both absolute and relative to the total rate), (ii) faster temporal offspring decay, (iii) higher intensity of repeating events, (iv) larger proportion of small clusters, and (v) larger spatial separation between parent and offspring, compared to regular tectonic activity. These differences also successfully discriminate seismicity within the Coso and Salton Sea geothermal fields in California before and after the expansion of geothermal production during the 1980s.
Federal Geothermal Research Program Update, FY 2000

DOE Office of Scientific and Technical Information (OSTI.GOV)

Renner, Joel Lawrence

2001-08-01

The Department of Energy's Geothermal Program serves two broad purposes: 1) to assist industry in overcoming near-term barriers by conducting cost-shared research and field verification that allows geothermal energy to compete in today's aggressive energy markets; and 2) to undertake fundamental research with potentially large economic payoffs. The four categories of work used to distinguish the research activities of the Geothermal Program during FY 2000 reflect the main components of real-world geothermal projects. These categories form the main sections of the project descriptions in this Research Update. Exploration Technology research focuses on developing instruments and techniques to discover hidden hydrothermalmore » systems and to explore the deep portions of known systems. Research in geophysical and geochemical methods is expected to yield increased knowledge of hidden geothermal systems. Reservoir Technology research combines laboratory and analytical investigations with equipment development and field testing to establish practical tools for resource development and management for both hydrothermal reservoirs and enhanced geothermal systems. Research in various reservoir analysis techniques is generating a wide range of information that facilitates development of improved reservoir management tools. Drilling Technology focuses on developing improved, economic drilling and completion technology for geothermal wells. Ongoing research to avert lost circulation episodes in geothermal drilling is yielding positive results. Conversion Technology research focuses on reducing costs and improving binary conversion cycle efficiency, to permit greater use of the more abundant moderate-temperature geothermal resource, and on the development of materials that will improve the operating characteristics of many types of geothermal energy equipment. Increased output and improved performance of binary cycles will result from investigations in heat cycle research.« less
Geothermal Economics Calculator (GEC) - additional modifications to final report as per GTP's request.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gowda, Varun; Hogue, Michael

This report will discuss the methods and the results from economic impact analysis applied to the development of Enhanced Geothermal Systems (EGS), conventional hydrothermal, low temperature geothermal and coproduced fluid technologies resulting in electric power production. As part of this work, the Energy & Geoscience Institute (EGI) has developed a web-based Geothermal Economics Calculator (Geothermal Economics Calculator (GEC)) tool that is aimed at helping the industry perform geothermal systems analysis and study the associated impacts of specific geothermal investments or technological improvements on employment, energy and environment. It is well-known in the industry that geothermal power projects will generate positivemore » economic impacts for their host regions. Our aim in the assessment of these impacts includes quantification of the increase in overall economic output due to geothermal projects and of the job creation associated with this increase. Such an estimate of economic impacts of geothermal investments on employment, energy and the environment will also help us understand the contributions that the geothermal industry will have in achieving a sustainable path towards energy production.« less
Constructing the deep temperature section of the Travale geothermal area in Italy, with the use of an electromagnetic geothermometer

NASA Astrophysics Data System (ADS)

Spichak, V. V.; Zakharova, O. K.

2015-01-01

The technology of electromagnetic geothermometer is applied for constructing the two-dimensional (2D) section of temperature in the Travale geothermal region in Italy up to a depth of 10 km. The joint analysis of this section, together with the previously constructed model of electric resistivity suggests that the heat transfer in the Travale region is rendered by the overheated vapor-gas fluids instead of liquid fluids as it was previously believed based on the interpretation of the resistivity model. Another important conclusion consists in the fact that, instead of two geothermal reservoirs, whose existence was previously tentatively inferred from the interpretation of the electromagnetic and seismic data, it is likely that there is a single deep reservoir with a shallow (near-surface) offshoot. From the constructed temperature distribution it can be seen that the temperature below a depth of 4 km exceeds 500°C, which indicates that drilling down to these depths could be useful for the subsequent exploitation of this geothermal reservoir.
Neutron imaging for geothermal energy systems

NASA Astrophysics Data System (ADS)

Bingham, Philip; Polsky, Yarom; Anovitz, Lawrence

2013-03-01

Geothermal systems extract heat energy from the interior of the earth using a working fluid, typically water. Three components are required for a commercially viable geothermal system: heat, fluid, and permeability. Current commercial electricity production using geothermal energy occurs where the three main components exist naturally. These are called hydrothermal systems. In the US, there is an estimated 30 GW of base load electrical power potential for hydrothermal sites. Next generation geothermal systems, named Enhanced Geothermal Systems (EGS), have an estimated potential of 4500 GW. EGSs lack in-situ fluid, permeability or both. As such, the heat exchange system must be developed or "engineered" within the rock. The envisioned method for producing permeability in the EGS reservoir is hydraulic fracturing, which is rarely practiced in the geothermal industry, and not well understood for the rocks typically present in geothermal reservoirs. High costs associated with trial and error learning in the field have led to an effort to characterize fluid flow and fracturing mechanisms in the laboratory to better understand how to design and manage EGS reservoirs. Neutron radiography has been investigated for potential use in this characterization. An environmental chamber has been developed that is suitable for reproduction of EGS pressures and temperatures and has been tested for both flow and precipitations studies with success for air/liquid interface imaging and 3D reconstruction of precipitation within the core.
Use of ASTER and MODIS thermal infrared data to quantify heat flow and hydrothermal change at Yellowstone National Park

USGS Publications Warehouse

Vaughan, R. Greg; Keszthelyi, Laszlo P.; Lowenstern, Jacob B.; Jaworowski, Cheryl; Heasler, Henry

2012-01-01

The overarching aim of this study was to use satellite thermal infrared (TIR) remote sensing to monitor geothermal activity within the Yellowstone geothermal area to meet the missions of both the U.S. Geological Survey and the Yellowstone National Park Geology Program. Specific goals were to: 1) address the challenges of monitoring the surface thermal characteristics of the > 10,000 spatially and temporally dynamic thermal features in the Park (including hot springs, pools, geysers, fumaroles, and mud pots) that are spread out over ~ 5000 km2, by using satellite TIR remote sensing tools (e.g., ASTER and MODIS), 2) to estimate the radiant geothermal heat flux (GHF) for Yellowstone's thermal areas, and 3) to identify normal, background thermal changes so that significant, abnormal changes can be recognized, should they ever occur (e.g., changes related to tectonic, hydrothermal, impending volcanic processes, or human activities, such as nearby geothermal development). ASTER TIR data (90-m pixels) were used to estimate the radiant GHF from all of Yellowstone's thermal features and update maps of thermal areas. MODIS TIR data (1-km pixels) were used to record background thermal radiance variations from March 2000 through December 2010 and establish thermal change detection limits. A lower limit for the radiant GHF estimated from ASTER TIR temperature data was established at ~ 2.0 GW, which is ~ 30–45% of the heat flux estimated through geochemical thermometry. Also, about 5 km2 of thermal areas was added to the geodatabase of mapped thermal areas. A decade-long time-series of MODIS TIR radiance data was dominated by seasonal cycles. A background subtraction technique was used in an attempt to isolate variations due to geothermal changes. Several statistically significant perturbations were noted in the time-series from Norris Geyser Basin, however many of these did not correspond to documented thermal disturbances. This study provides concrete examples of the strengths and limitations of current satellite TIR monitoring of geothermal areas, highlighting some specific areas that can be improved. This work provides a framework for future satellite-based thermal monitoring at Yellowstone and other volcanic and geothermal systems
Recovery Act: Cedarville School District Retrofit of Heating and Cooling Systems with Geothermal Heat Pumps and Ground Source Water Loops

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jarrell, Mark

Cedarville School District retrofitted the heating and cooling systems in three campus areas (High School, Middle School, and Upper Elementary School) with geothermal heat pumps and ground source water loops, as a demonstration project for the effective implementation of geothermal heat pump systems and other energy efficiency and air quality improvements.

Review of subduction and its association with geothermal system in Sumatera-Java

NASA Astrophysics Data System (ADS)

Ladiba, A. F.; Putriyana, L.; Sibarani, B. br.; Soekarno, H.

2017-12-01

Java and Sumatera have the largest geothermal resources in Indonesia, in which mostly are spatially associated with volcanoes of subduction zones. However, those volcanoes are not distributed in a regular pattern due to the difference of subduction position. Subduction position in java is relatively more perpendicular to the trench than in Sumatera. In addition, Java has a concentration of large productive geothermal field with vapour dominated system in the western part of Java, which may be caused by the various subduction dip along the island. In order to understand the relationship between the subduction process and geothermal system in the subduction zone volcanoes, we examined several kinematic parameters of subduction that potentially relevant to the formation of geothermal system in overriding plate such as slab dip, subduction rate, and direction of subduction. Data and information regarding tectonic setting of Sumatera and Java and productive geothermal field in Sumatera and Java have been collected and evaluated. In conclusion, there are three condition that caused the geothermal fluid to be more likely being in vapour phase, which are: the subduction is in an orthogonal position, the slab dip is high, and rate of subduction is high. Although there are plenty researches of subduction zone volcanoes, only a few of them present information about its formation and implication to the geothermal system. The result of this study may be used as reference in exploration of geothermal field in mutual geologic environment.
Geothermal Potential of the Cascade and Aleutian Arcs, with Ranking of Individual Volcanic Centers for their Potential to Host Electricity-Grade Reservoirs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shevenell, Lisa; Coolbaugh, Mark; Hinz, Nick

This project brings a global perspective to volcanic arc geothermal play fairway analysis by developing statistics for the occurrence of geothermal reservoirs and their geoscience context worldwide in order to rank U.S. prospects. The focus of the work was to develop play fairways for the Cascade and Aleutian arcs to rank the individual volcanic centers in these arcs by their potential to host electricity grade geothermal systems. The Fairway models were developed by describing key geologic factors expected to be indicative of productive geothermal systems in a global training set, which includes 74 volcanic centers world-wide with current power production.more » To our knowledge, this is the most robust geothermal benchmark training set for magmatic systems to date that will be made public.« less
Fracture development within a stratovolcano: The Karaha-Telaga Bodas geothermal field, Java volcanic arc

USGS Publications Warehouse

Nemcok, M.; Moore, J.N.; Allis, R.; McCulloch, J.

2004-01-01

Karaha-Telaga Bodas, a vapour-dominated geothermal system located in an active volcano in western Java, is penetrated by more than two dozen deep geothermal wells reaching depths of 3 km. Detailed paragenetic and fluid-inclusion studies from over 1000 natural fractures define the liquid-dominated, transitional and vapour-dominated stages in the evolution of this system. The liquid-dominated stage was initiated by ashallow magma intrusion into the base of the volcanic cone. Lava and pyroclastic flows capped a geothermal system. The uppermost andesite flows were only weakly fractured due to the insulating effect of the intervening altered pyroclastics, which absorbed the deformation. Shear and tensile fractures that developed were filled with carbonates at shallow depths, and by quartz, epidote and actinolite at depths and temperatures over 1 km and 300??C. The system underwent numerous cycles of overpressuring, documented by subhorizontal tensile fractures, anastomosing tensile fracture patterns and implosion breccias. The development of the liquidsystem was interrupted by a catastrophic drop in fluid pressures. As the fluids boiled in response to this pressure drop, chalcedony and quartz were selectively deposited in fractures that had the largest apertures and steep dips. The orientations of these fractures indicate that the escaping overpressured fluids used the shortest possible paths to the surface. Vapour-dominated conditions were initiated at this time within a vertical chimney overlying the still hot intrusion. As pressures declined, these conditions spread outward to form the marginal vapour-dominated region encountered in the drill holes. Downward migration of the chimney, accompanied by growth of the marginal vapour-dominated regime, occurred as the intrusion cooled and the brittle-ductile transition migrated to greater depths. As the liquids boiled off, condensate that formed at the top of the vapour-dominated zone percolated downward and low-salinity meteoric water entered the marginal parts of the system. Calcite, anhydrite and fluorite precipitated in fractures on heating. Progressive sealing of the fractures resulted in the downward migration of the cap rock. In response to decreased pore pressure in the expanding vapour zone, walls of the fracture system within the vapour-dominated reservoir progressively collapsed. It left only residual permeability in the remaining fracture volume, with apertures supported only by asperities or propping breccia. In places where normal stresses acting on the fracture walls exceeded the compressive strength of the wall rock, the fractures have completely collapsed. Fractures within the present-day cap rock include strike- and oblique-slip faults, normal faults and tensile fractures, all controlled by a strike-slip stress regime. The reservoir is characterized by normal faults and tensile fractures controlled by a normal-fault stress regime. The fractures show no evidence that the orientation of the stress field has changed since fracture propagation began. Fluid migration in the lava and pyroclastic flows is controlled by fractures. Matrix permeability controls fluid flow in the sedimentary sections of the reservoir. Productive fractures are typically roughly perpendicular to the minimum compressive stress, ??3, and are prone to slip and dilation within the modern stress regime. ?? The Geological Society of London 2004.
Laboratory investigations of steam flow in a porous medium

USGS Publications Warehouse

Herkelrath, W.N.; Moench, A.F.; O'Neal, II

1983-01-01

Experiments were carried out in the laboratory to test a theory of transient flow of pure steam in a uniform porous medium. This theory is used in modeling pressure transient behavior in vapor dominated geothermal systems. Transient, superheated steam flow experiments were run by bringing a cylinder of porous material to a uniform initial pressure and then making a step increase in pressure at one end of the sample while monitoring the pressure transient breakthrough at the other end. It was found in experiments run at 100°, 125°, and 146°C that the time required for steam pressure transients to propagate through an unconsolidated material containing sand, silt, and clay was 10–25 times longer than predicted by conventional superheated steam flow theory. It is hypothesized that the delay in the steam pressure transient was caused by adsorption of steam in the porous sample. In order to account for steam adsorption, a sink term was included in the conservation of mass equation. In addition, energy transfer in the system has to be considered because latent heat is released when steam adsorption occurs, increasing the sample temperature by as much as 10°C. Finally, it was recognized that the steam pressure was a function of both the temperature and the amount of adsorption in the sample. This function was assumed to be an equilibrium adsorption isotherm, which was determined by experiment. By solving the modified mass and energy equations numerically, subject to the empirical adsorption isotherm relationship, excellent theoretical simulation of the experiments was achieved.
Analysis of gravity data beneath Endut geothermal prospect using horizontal gradient and Euler deconvolution

NASA Astrophysics Data System (ADS)

Supriyanto, Noor, T.; Suhanto, E.

2017-07-01

The Endut geothermal prospect is located in Banten Province, Indonesia. The geological setting of the area is dominated by quaternary volcanic, tertiary sediments and tertiary rock intrusion. This area has been in the preliminary study phase of geology, geochemistry, and geophysics. As one of the geophysical study, the gravity data measurement has been carried out and analyzed in order to understand geological condition especially subsurface fault structure that control the geothermal system in Endut area. After precondition applied to gravity data, the complete Bouguer anomaly have been analyzed using advanced derivatives method such as Horizontal Gradient (HG) and Euler Deconvolution (ED) to clarify the existance of fault structures. These techniques detected boundaries of body anomalies and faults structure that were compared with the lithologies in the geology map. The analysis result will be useful in making a further realistic conceptual model of the Endut geothermal area.
Numerical and experimental design of coaxial shallow geothermal energy systems

NASA Astrophysics Data System (ADS)

Raghavan, Niranjan

Geothermal Energy has emerged as one of the front runners in the energy race because of its performance efficiency, abundance and production competitiveness. Today, geothermal energy is used in many regions of the world as a sustainable solution for decreasing dependence on fossil fuels and reducing health hazards. However, projects related to geothermal energy have not received their deserved recognition due to lack of computational tools associated with them and economic misconceptions related to their installation and functioning. This research focuses on numerical and experimental system design analysis of vertical shallow geothermal energy systems. The driving force is the temperature difference between a finite depth beneath the earth and its surface stimulates continuous exchange of thermal energy from sub-surface to the surface (a geothermal gradient is set up). This heat gradient is captured by the circulating refrigerant and thus, tapping the geothermal energy from shallow depths. Traditionally, U-bend systems, which consist of two one-inch pipes with a U-bend connector at the bottom, have been widely used in geothermal applications. Alternative systems include coaxial pipes (pipe-in-pipe) that are the main focus of this research. It has been studied that coaxial pipes have significantly higher thermal performance characteristics than U-bend pipes, with comparative production and installation costs. This makes them a viable design upgrade to the traditional piping systems. Analytical and numerical heat transfer analysis of the coaxial system is carried out with the help of ABAQUS software. It is tested by varying independent parameters such as materials, soil conditions and effect of thermal contact conductance on heat transfer characteristics. With the above information, this research aims at formulating a preliminary theoretical design setup for an experimental study to quantify and compare the heat transfer characteristics of U-bend and coaxial geothermal piping systems. Based on the simulations and experiments, the effect of parameters on the overall operating costs is studied. Finally, with the results obtained, the economics and return on investment behind coaxial geothermal energy systems are discussed. Government policies on renewable energy are explained, highlighting the energy incentives associated with geothermal energy in the United States. The findings of this research provides a platform for further shallow geothermal energy system studies with an immense potential to revolutionize the energy industry in the future.
Geothermal Research | Geothermal Technologies | NREL

Science.gov Websites

. Impact Analysis Conducting analyses to determine the viability of geothermal energy production and Hybrid Systems Exploring the potential benefits of combining geothermal with other renewable energy Designing new models and studying new techniques to increase the production of geothermal energy.
Microbial community dynamics in Inferno Crater Lake, a thermally fluctuating geothermal spring

PubMed Central

Ward, Laura; Taylor, Michael W; Power, Jean F; Scott, Bradley J; McDonald, Ian R; Stott, Matthew B

2017-01-01

Understanding how microbial communities respond and adjust to ecosystem perturbation is often difficult to interpret due to multiple and often simultaneous variations in observed conditions. In this research, we investigated the microbial community dynamics of Inferno Crater Lake, an acidic geothermal spring in New Zealand with a unique thermal cycle that varies between 30 and 80 °C over a period of 40–60 days. Using a combination of next-generation sequencing, geochemical analysis and quantitative PCR we found that the microbial community composition was predominantly chemolithotrophic and strongly associated with the thermal cycle. At temperatures >65 °C, the microbial community was dominated almost exclusively by sulphur-oxidising archaea (Sulfolobus-like spp.). By contrast, at mesophilic temperatures the community structure was more mixed, comprising both archaea and bacteria but dominated primarily by chemolithotrophic sulphur and hydrogen oxidisers. Multivariate analysis of physicochemical data confirmed that temperature was the only significant variable associated with community turnover. This research contributes to our understanding of microbial community dynamics in variable environments, using a naturally alternating system as a model and extends our limited knowledge of acidophile ecology in geothermal habitats. PMID:28072418
Federal Geothermal Research Program Update Fiscal Year 2000

DOE Office of Scientific and Technical Information (OSTI.GOV)

Renner, J.L.

2001-08-15

The Department of Energy's Geothermal Program serves two broad purposes: (1) to assist industry in overcoming near-term barriers by conducting cost-shared research and field verification that allows geothermal energy to compete in today's aggressive energy markets; and (2) to undertake fundamental research with potentially large economic payoffs. The four categories of work used to distinguish the research activities of the Geothermal Program during FY 2000 reflect the main components of real-world geothermal projects. These categories form the main sections of the project descriptions in this Research Update. Exploration Technology research focuses on developing instruments and techniques to discover hidden hydrothermalmore » systems and to explore the deep portions of known systems. Research in geophysical and geochemical methods is expected to yield increased knowledge of hidden geothermal systems. Reservoir Technology research combines laboratory and analytical investigations with equipment development and field testing to establish practical tools for resource development and management for both hydrothermal reservoirs and enhanced geothermal systems. Research in various reservoir analysis techniques is generating a wide range of information that facilitates development of improved reservoir management tools. Drilling Technology focuses on developing improved, economic drilling and completion technology for geothermal wells. Ongoing research to avert lost circulation episodes in geothermal drilling is yielding positive results. Conversion Technology research focuses on reducing costs and improving binary conversion cycle efficiency, to permit greater use of the more abundant moderate-temperature geothermal resource, and on the development of materials that will improve the operating characteristics of many types of geothermal energy equipment. Increased output and improved performance of binary cycles will result from investigations in heat cycle research.« less
Helium isotope study of geothermal features in Chile with field and laboratory data

DOE Data Explorer

Dobson, Patrick

2013-02-11

Helium isotope and stable isotope data from the El Tatio, Tinginguirica, Chillan, and Tolhuaca geothermal systems, Chile. Data from this submission are discussed in: Dobson, P.F., Kennedy, B.M., Reich, M., Sanchez, P., and Morata, D. (2013) Effects of volcanism, crustal thickness, and large scale faulting on the He isotope signatures of geothermal systems in Chile. Proceedings, 38th Workshop on Geothermal Reservoir Engineering, Stanford University, Feb. 11-13, 2013
Stable-isotope studies of rocks and secondary minerals in a vapor-dominated hydrothermal system at The Geysers, Sonoma County, California

NASA Astrophysics Data System (ADS)

Lambert, Steven J.; Epstein, Samuel

1992-11-01

The Geysers, a vapor-dominated hydrothermal system, is developed in host rock of the Franciscan Formation, which contains veins of quartz and calcite whose δ 18O values record the temperatures and isotopic compositions of fluids prevailing during at least two different episodes of rock-fluid interaction. The first episode took place at about 200°C, during which marine silica and carbonate apparently interacted with ocean water entrapped in the sediments to form veins of quartz and calcite whose δ 18O values were around +19 and +16%, respectively. The calculated water/mineral ratios were less than unity. The water may have profoundly influenced the δ 18O values of spilitic basalts during their metamorphism to greenstones. Serpentinization and structural emplacement of ophiolite slabs were isotopically unrelated to this episode, which was essentially a low-grade (post-Cretaceous?) burial metamorphism. D/H ratios of actinolite, chlorite, and micas in host rocks were more profoundly altered during this episode than were 18O/ 16O ratios. A paleogeothermal gradient of about 53°C/km has been inferred for this episode, from δ 18O-depth distributions of vein minerals. The second episode, in part recorded by cogenetic vein quartz and calcite δ 18O values of +4 to +6% and +1 to +3%, respectively, began with large quantities of meteoric water circulating in fractures in the rock at temperatures of 160-180°C in response to the initiation of the Pliocene-Pleistocene Clear Lake magmatism. The temperature rose, and with the restricted circulation of fluids the ancestral hot-water system evolved into the presently active vapor-dominated system, which according to the cogenetic vein quartz and calcite δ 18O values involved temperatures as high as 320°C and fluid/mineral ratios near unity. The change in the oxygen-isotopic composition of the serpentinite within the host rock during this later activity was negligible. The δ 13C values of vein calcite at The Geysers reflect both a marine carbonate and organic component of carbon, but carbon-isotope exchange has been facilitated by the vapor-dominated hydrothermal fluid to a greater degree than in any other episode or in other hot-water systems.
Neil Popovich | NREL

Science.gov Websites

(SEPIO). His areas of expertise include low temperature geothermal power production systems; mineral recovery from geothermal brines; fuel cell systems analysis/manufacturing/engineering; instrumentation
Geothermal Potential Analysis Using Landsat 8 and Sentinel 2 (Case Study: Mount Ijen)

NASA Astrophysics Data System (ADS)

Sukojo, B. M.; Mardiana, R.

2017-12-01

Geothermal energy is also a heat energy contained in the earth’s internal. Indonesia has a total geothermal potential of around 27 GWe. The government is eager for the development of geothermal in Indonesia can run well so that geothermal can act as one of the pillars of national energy. However, the geothermal potential has not been fully utilized. One of the geothermal potention is Mount Ijen. Mount Ijen is a strato volcano that has a crater lake with a depth of about 190 m and has a very high degree of acidity and the volume of lake water is very large. With the abundance of potential geothermal potential in Indonesia, it is necessary to have an activity in the form of integrated geoscience studies to be able to maximize the potential content that exists in a geothermal area. One of the studies conducted is to do potential mapping. This research performs image data processing of Landsat 8, Sentinel 2, RBI Map, and preliminary survey data. This research carried out the Vegetation Index, surface temperature and altitude. The equipment used in this research includes image processing software, number processing software, GPS Handheld and Laptop. Surface Temperatures in the Mount Ijen have anomalies with large temperatures ranging between 18° C to 38° C. The best correlation value of altitude and ground surface temperature is -0.89 ie the correlation of January surface temperature. While the correlation value of Landsat 8 and Sentinel 2 vegetation index was 0.81. The land cover confidence matrix scored 80%. Land cover in the research area is dominated by forests by 35% of the research area. There is a potential area of geothermal potential is very high on Mount Ijen with an area of 39.43 hectares located in Wongsorejo District and adjacent to District Sempol.
The USGS national geothermal resource assessment: An update

USGS Publications Warehouse

Williams, C.F.; Reed, M.J.; Galanis, S.P.; DeAngelo, J.

2007-01-01

The U. S. Geological Survey (USGS) is working with the Department of Energy's (DOE) Geothermal Technologies Program and other geothermal organizations on a three-year effort to produce an updated assessment of available geothermal resources. The new assessment will introduce significant changes in the models for geothermal energy recovery factors, estimates of reservoir volumes, and limits to temperatures and depths for electric power production. It will also include the potential impact of evolving Enhanced Geothermal Systems (EGS) technology. An important focus in the assessment project is on the development of geothermal resource models consistent with the production histories and observed characteristics of exploited geothermal fields. New models for the recovery of heat from heterogeneous, fractured reservoirs provide a physically realistic basis for evaluating the production potential of both natural geothermal reservoirs and reservoirs that may be created through the application of EGS technology. Project investigators have also made substantial progress studying geothermal systems and the factors responsible for their formation through studies in the Great Basin-Modoc Plateau region, Coso, Long Valley, the Imperial Valley and central Alaska, Project personnel are also entering the supporting data and resulting analyses into geospatial databases that will be produced as part of the resource assessment.
A preliminary assessment of a medium-enthalpy geothermal resource in Nagu (Tibet) people's republic of China

DOE Office of Scientific and Technical Information (OSTI.GOV)

Battistelli, A.; Rivera, R.J.; D'Amore, F.

1991-01-01

The Nagqu geothermal field is a single-phase, liquid-dominated system at reservoir conditions, having a high gas content. This field is located at an elevation of about 4,500 m (asl), in the vicinity of the City of Nagqu, which is one of the most important cities of Tibet.The reservoir rock is made of a highly fractured, low-permeability sedimentary sequence. During the implementation of the study described in this paper, fluid production was mainly obtained from two out of four possible productive wells. The main fault systems are located in a NE-SW and E-W directions, which seem to control fluid movement atmore » depth. The geothermal field is restricted to a small area where hydrothermal manifestations are located. Reservoir temperature is 114 C, gas content is in the range of 0.5 to 0.6% by mass, being mainly CO{sub 2}. Reservoir transmissivity in the area of the wells is very high. Reservoir response to changes in flow rate in any of the producing wells could be detected almost immediately in the observation wells, which were distant between 300 to 900 m, depending on the production-observation well arrangement. Calcium carbonate scaling was present in all producing wells. This deposition was controlled by the CO{sub 2} partial pressure. Description of well testing results is provided, as well as the thermodynamics and geochemistry of reservoir fluids.« less
Novel approaches for an enhanced geothermal development of residential sites

NASA Astrophysics Data System (ADS)

Schelenz, Sophie; Firmbach, Linda; Shao, Haibing; Dietrich, Peter; Vienken, Thomas

2015-04-01

An ongoing technological enhancement drives an increasing use of shallow geothermal systems for heating and cooling applications. However, even in areas with intensive shallow geothermal use, planning of geothermal systems is in many cases solely based on geological maps, drilling databases, and literature references. Thus, relevant heat transport parameters are rather approximated than measured for the specific site. To increase the planning safety and promote the use of renewable energies in the domestic sector, this study investigates a novel concept for an enhanced geothermal development of residential neighbourhoods. This concept is based on a site-specific characterization of subsurface conditions and the implementation of demand-oriented geothermal usage options. Therefore, an investigation approach has been tested that combines non-invasive with minimum-invasive exploration methods. While electrical resistivity tomography has been applied to characterize the geological subsurface structure, Direct Push soundings enable a detailed, vertical high-resolution characterization of the subsurface surrounding the borehole heat exchangers. The benefit of this site-specific subsurface investigation is highlighted for 1) a more precise design of shallow geothermal systems and 2) a reliable prediction of induced long-term changes in groundwater temperatures. To guarantee the financial feasibility and practicability of the novel geothermal development, three different options for its implementation in residential neighbourhoods were consequently deduced.
Energy Systems Integration Facility News | Energy Systems Integration

Science.gov Websites

, 2018 News Release: NREL Taps Young to Oversee Geothermal Energy Program In her new role, Young will work closely with NREL management to establish the lab's geothermal energy portfolio, including research and development geared toward advancing the use of geothermal energy as a renewable power source
RiverHeath: Neighborhood Loop Geothermal Exchange System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Geall, Mark

2016-07-11

The goal of the RiverHeath project is to develop a geothermal exchange system at lower capital infrastructure cost than current geothermal exchange systems. The RiverHeath system features an innovative design that incorporates use of the adjacent river through river-based heat exchange plates. The flowing water provides a tremendous amount of heat transfer. As a result, the installation cost of this geothermal exchange system is lower than more traditional vertical bore systems. Many urban areas are located along rivers and other waterways. RiverHeath will serve as a template for other projects adjacent to the water.
"Assistance to States on Geothermal Energy"

DOE Office of Scientific and Technical Information (OSTI.GOV)

Linda Sikkema; Jennifer DeCesaro

2006-07-10

This final report summarizes work carried out under agreement with the U.S. Department of Energy, related to geothermal energy policy issues. This project has involved a combination of outreach and publications on geothermal energy—Contract Number DE-FG03-01SF22367—with a specific focus on educating state-level policymakers. Education of state policymakers is vitally important because state policy (in the form of incentives or regulation) is a crucial part of the success of geothermal energy. State policymakers wield a significant influence over all of these policies. They are also in need of high quality, non-biased educational resources which this project provided. This project provided outreachmore » to legislatures, in the form of responses to information requests on geothermal energy and publications. The publications addressed: geothermal leasing, geothermal policy, constitutional and statutory authority for the development of geothermal district energy systems, and state regulation of geothermal district energy systems. These publications were distributed to legislative energy committee members, and chairs, legislative staff, legislative libraries, and other related state officials. The effect of this effort has been to provide an extensive resource of information about geothermal energy for state policymakers in a form that is useful to them. This non-partisan information has been used as state policymakers attempt to develop their own policy proposals related to geothermal energy in the states. Coordination with the National Geothermal Collaborative: NCSL worked and coordinated with the National Geothermal Collaborative (NGC) to ensure that state legislatures were represented in all aspects of the NGC's efforts. NCSL participated in NGC steering committee conference calls, attended and participated in NGC business meetings and reviewed publications for the NGC. Additionally, NCSL and WSUEP staff drafted a series of eight issue briefs published by the NGC. The briefs addressed: Benefits of Geothermal Energy Common Questions about Geothermal Energy Geothermal Direct Use Geothermal Energy and Economic Development Geothermal Energy: Technologies and Costs Location of Geothermal Resources Geothermal Policy Options for States Guidelines for Siting Geothermal Power Plants and Electricity Transmission Lines« less
Three-dimensional Q -1 model of the Coso Hot Springs Known Geothermal Resource Area

NASA Astrophysics Data System (ADS)

Young, Chi-Yuh; Ward, Ronald W.

1980-05-01

Observations of teleseismic P waves above geothermal systems exhibit travel time delays and anomalously high seismic attenuation, which is extremely useful in estimating the thermal regime and the potential of the system. A regional telemetered network of sixteen stations was operated by the U.S. Geological Survey in the Coso Hot Springs Known Geothermal Resources Area (KGRA) for such studies from September 1975 to October 1976. Subsequently, they deployed a portable Centipede array of 26 three-component stations near the center of the anomaly. The seismograms of 44 events recorded by the telemetered array and nine events by the Centipede array were analyzed using the reduced spectral ratio technique to determine the differential attenuation factor δt* for the events recorded with the highest signal-to-noise ratio. The δt* variation observed across the Coso Hot Springs KGRA were small (<0.2 s). A three-dimensional generalized linear inversion of the δt* observations was performed using a three-layer model. A shallow zone of high attenuation exists within the upper 5 km in a region bounded by Coso Hot Springs, Devils Kitchen, and Sugarloaf Mountain probably corresponding to a shallow vapor liquid mixture or `lossy' near surface lithology. No zones of significantly high attenuation occur between 5- and 12- km depth. Between the depth of 12-20 km a thick zone of high attenuation (Q <50) exists, offset toward the east from the surface anomaly.

Analysis of induced seismicity at The Geysers geothermal field, California

NASA Astrophysics Data System (ADS)

Emolo, A.; Maercklin, N.; Matrullo, E.; Orefice, A.; Amoroso, O.; Convertito, V.; Sharma, N.; Zollo, A.

2012-12-01

Fluid injection, steam extraction, and reservoir stimulation in geothermal systems lead to induced seismicity. While in rare cases induced events may be large enough to pose a hazard, on the other hand the microseismicity provides information on the extent and the space-time varying properties of the reservoir. Therefore, microseismic monitoring is important, both for mitigation of unwanted effects of industrial operations and for continuous assessment of reservoir conditions. Here we analyze induced seismicity at The Geysers geothermal field in California, a vapor-dominated field with the top of the main steam reservoir some 1-3 km below the surface. Commercial exploitation began in the 1960s, and the seismicity increased with increasing field development. We focus our analyses on induced seismicity recorded between August 2007 and October 2011. Our calibrated waveform database contains some 15000 events with magnitudes between 1.0 and 4.5 and recorded by the LBNL Geysers/Calpine surface seismic network. We associated all data with events from the NCEDC earthquake catalog and re-picked first arrival times. Using selected events with at least 20 high-quality P-wave picks, we determined a minimum 1-D velocity model using VELEST. A well-constrained P-velocity model shows a sharp velocity increase at 1-2 km depth (from 3 to 5 km/s) and then a gradient-like trend down to about 5 km depth, where velocities reach values of 6-7 km/s. The station corrections show coherent, relatively high, positive travel time delays in the NW zone, thus indicating a strong lateral variation of the P-wave velocities. We determined an average Vp-to-Vs ratio of 1.67, which is consistent with estimates from other authors for the same time period. The events have been relocated in the new model using a non-linear probabilistic methods. The seismicity appears spatially diffused in a 15x10 km2 area elongated in NW-SE direction, and earthquake depths range between 0 and 6 km. As in previous seismicity studies of this geothermal field, we find that events occurring in the NW sector are on average deeper than in the SE area. To infer the present stress regime, we computed focal mechanisms of a large event data set with M > 2, using P-wave first-arrival polarities. The found fault-plane solutions show a dominant strike-slip and normal faulting mechanisms, with P and T axes coherently oriented with expected regional stress field for the area. We also determined the main seismic source parameters from a multi-step, iterative inversion of P-wave displacement spectra, assuming a four-parameters spectral model and a constant-Q attenuation mechanism. In particular, we computed seismic moments, source radii and stress drops. We observe a self-similar scaling of source parameters in the whole investigated magnitude range, with a nearly constant stress-drop of 20 and 120 MPa depending on the use of Brune (1970) or Madariaga (1976)'s source model respectively.
Assessment of the origin and geothermal potential of the thermal waters by hydro-isotope geochemistry: Eskisehir province, Turkey.

PubMed

Yuce, Galip; Italiano, Francesco; Yasin, Didem; Taskiran, Lutfi; Gulbay, Ahmet Hilmi

2017-05-01

The thermal fluids vented over Eskisehir province have been investigated for their origin and to estimate the geothermal potential of the area. Thermal waters as well as bubbling and dissolved gases were collected and analysed for their chemical and isotopic features. Their isotopic composition varies in the range from -11.5 to -7.7 ‰ for δ 18 O, -84 and -57 ‰ for δ 2 H, and 0-7.2 TU for tritium. The gases (bubbling and dissolved) are mostly N 2 -dominated with a significant amount of CO 2 . The helium isotopic ratios are in the range of 0.2-0.66 R/Rac, indicate remarkable mantle-He contribution ranging between 2 and 10 % in the whole study area. Considering the estimated geothermal gradient about three times higher than the normal gradient, and the reservoir temperatures estimated to be between 50 and 100 °C using quartz and chalcedony geothermometers, a circulation model was built where possible mixing with shallow waters cool down the uprising geothermal fluids.
Geothermal Data Collection and Interpretation in the State of Alabama: Early Results from the ARRA Geothermal Energy Initiative

NASA Astrophysics Data System (ADS)

Hills, D. J.; Osborne, T. E.; McIntyre, M. R.; Pashin, J. C.

2011-12-01

The Geological Survey of Alabama (GSA) is expanding its efforts to collect, develop, maintain, and analyze statewide geothermal data and to make this information widely and easily accessible to the public through the National Geothermal Data System. The online availability of this data will aid in the effective development of geothermal energy applications and reduce the risks associated with the initial stages of geothermal project development. To this end, the GSA is participating in a collaborative project that the Arizona Geological Survey is coordinating in cooperation with the Association of American State Geologists and with the support of the U.S. Department of Energy as part of the American Reinvestment and Recovery Act. Wells drilled for the exploration and production of hydrocarbons are the primary sources of geothermal data in Alabama. To date, more than 1,200 wells in coalbed methane (CBM) fields in the Black Warrior Basin (BWB) have been examined, in addition to over 500 conventional wells in the basin. Pottsville Formation (Pennsylvanian) bottom-hole temperatures (BHTs) range from less than 80°F to more than 140°F in wells reaching total depth between 1,000 and 6,000 feet (ft). Temperature and depth correlate with a coefficient of determination (r2) of 0.72, reflecting significant variation of the modern geothermal gradient. Mapping and statistical analysis confirm that geothermal gradient in the CBM fairway is typically between 6 and 12°F/1,000 ft. BHTs in the conventional wells penetrating the BWB show even greater variation, with temperature and depth correlating with an r2 of only 0.27. This variability owes to numerous factors, including stratigraphy, lithology, thermal conductivity, and geothermal gradient. Indeed, these wells reach total depth between 500 and 12,000 ft in carbonate and siliciclastic formations ranging in age from Cambrian to Mississippian. The Cambrian section is dominated by low conductivity shale, whereas the Ordovician-Mississippian section contains mainly high-conductivity carbonate. The Upper Mississippian, by contrast, includes complexly interstratified carbonate and siliciclastic rock types with variable thermal conductivity. The Gulf Coast basin of southwest Alabama contains numerous wells penetrating a Mesozoic stratigraphic section that is between 12,000 and 22,000 ft thick. Most wells reach total depth in Jurassic carbonate and sandstone or in Upper Cretaceous sandstone, and the deepest wells have BHTs greater than 400°F. Temperature readings are available at multiple depths for numerous wells, due to multiple log runs. These wells are particularly valuable owing to the availability of data from formations that are not reservoirs. Geothermal gradient is affected by geopressure, which is typically present below 10,000 ft. Gradient is further affected by a thick evaporite section, which can include more than 3,000 ft of salt in the Jurassic section. Thermal data from these wells are invaluable for characterizing petroleum systems and for identifying zones of warm water that can be used as geothermal energy sources.
Distribution and diversity of Verrucomicrobia methanotrophs in geothermal and acidic environments.

PubMed

Sharp, Christine E; Smirnova, Angela V; Graham, Jaime M; Stott, Matthew B; Khadka, Roshan; Moore, Tim R; Grasby, Stephen E; Strack, Maria; Dunfield, Peter F

2014-06-01

Recently, methanotrophic members of the phylum Verrucomicrobia have been described, but little is known about their distribution in nature. We surveyed methanotrophic bacteria in geothermal springs and acidic wetlands via pyrosequencing of 16S rRNA gene amplicons. Putative methanotrophic Verrucomicrobia were found in samples covering a broad temperature range (22.5-81.6°C), but only in acidic conditions (pH 1.8-5.0) and only in geothermal environments, not in acidic bogs or fens. Phylogenetically, three 16S rRNA gene sequence clusters of putative methanotrophic Verrucomicrobia were observed. Those detected in high-temperature geothermal samples (44.1-81.6°C) grouped with known thermoacidiphilic 'Methylacidiphilum' isolates. A second group dominated in moderate-temperature geothermal samples (22.5-40.1°C) and a representative mesophilic methanotroph from this group was isolated (strain LP2A). Genome sequencing verified that strain LP2A possessed particulate methane monooxygenase, but its 16S rRNA gene sequence identity to 'Methylacidiphilum infernorum' strain V4 was only 90.6%. A third group clustered distantly with known methanotrophic Verrucomicrobia. Using pmoA-gene targeted quantitative polymerase chain reaction, two geothermal soil profiles showed a dominance of LP2A-like pmoA sequences in the cooler surface layers and 'Methylacidiphilum'-like pmoA sequences in deeper, hotter layers. Based on these results, there appears to be a thermophilic group and a mesophilic group of methanotrophic Verrucomicrobia. However, both were detected only in acidic geothermal environments. © 2014 Society for Applied Microbiology and John Wiley & Sons Ltd.
Microbial diversity in nonsulfur, sulfur and iron geothermal steam vents.

PubMed

Benson, Courtney A; Bizzoco, Richard W; Lipson, David A; Kelley, Scott T

2011-04-01

Fumaroles, commonly called steam vents, are ubiquitous features of geothermal habitats. Recent studies have discovered microorganisms in condensed fumarole steam, but fumarole deposits have proven refractory to DNA isolation. In this study, we report the development of novel DNA isolation approaches for fumarole deposit microbial community analysis. Deposit samples were collected from steam vents and caves in Hawaii Volcanoes National Park, Yellowstone National Park and Lassen Volcanic National Park. Samples were analyzed by X-ray microanalysis and classified as nonsulfur, sulfur or iron-dominated steam deposits. We experienced considerable difficulty in obtaining high-yield, high-quality DNA for cloning: only half of all the samples ultimately yielded sequences. Analysis of archaeal 16S rRNA gene sequences showed that sulfur steam deposits were dominated by Sulfolobus and Acidianus, while nonsulfur deposits contained mainly unknown Crenarchaeota. Several of these novel Crenarchaeota lineages were related to chemoautotrophic ammonia oxidizers, indicating that fumaroles represent a putative habitat for ammonia-oxidizing Archaea. We also generated archaeal and bacterial enrichment cultures from the majority of the deposits and isolated members of the Sulfolobales. Our results provide the first evidence of Archaea in geothermal steam deposits and show that fumaroles harbor diverse and novel microbial lineages. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.
Resistivity imaging of Aluto-Langano geothermal field using 3-D magnetotelluric inversion

NASA Astrophysics Data System (ADS)

Cherkose, Biruk Abera; Mizunaga, Hideki

2018-03-01

Magnetotelluric (MT) method is a widely used geophysical method in geothermal exploration. It is used to image subsurface resistivity structures from shallow depths up to several kilometers of depth. Resistivity imaging using MT method in high-enthalpy geothermal systems is an effective tool to identify conductive clay layers that cover the geothermal systems and to detect a potential reservoir. A resistivity model is vital for deciding the location of pilot and production sites at the early stages of a geothermal project. In this study, a 3-D resistivity model of Aluto-Langano geothermal field was constructed to map structures related to a geothermal resource. The inversion program, ModEM was used to recover the 3-D resistivity model of the study area. The 3-D inversion result revealed the three main resistivity structures: a high-resistivity surface layer related to unaltered volcanic rocks at shallow depth, underlain by a conductive zone associated with the presence of conductive clay minerals, predominantly smectite. Beneath the conductive layer, the resistivity increases gradually to higher values related to the formation of high-temperature alteration minerals such as chlorite and epidote. The resistivity model recovered from 3-D inversion in Aluto-Langano corresponds very well to the conceptual model for high-enthalpy volcanic geothermal systems. The conductive clay cap is overlying the resistive propylitic upflow zone as confirmed by the geothermal wells in the area.
Stress concentrations at structural discontinuities in active fault zones in the western United States: Implications for permeability and fluid flow in geothermal fields

USGS Publications Warehouse

Siler, Drew; Hinz, Nicholas H.; Faulds, James E.

2018-01-01

Slip can induce concentration of stresses at discontinuities along fault systems. These structural discontinuities, i.e., fault terminations, fault step-overs, intersections, bends, and other fault interaction areas, are known to host fluid flow in ore deposition systems, oil and gas reservoirs, and geothermal systems. We modeled stress transfer associated with slip on faults with Holocene-to-historic slip histories at the Salt Wells and Bradys geothermal systems in western Nevada, United States. Results show discrete locations of stress perturbation within discontinuities along these fault systems. Well field data, surface geothermal manifestations, and subsurface temperature data, each a proxy for modern fluid circulation in the fields, indicate that geothermal fluid flow is focused in these same areas where stresses are most highly perturbed. These results suggest that submeter- to meter-scale slip on these fault systems generates stress perturbations that are sufficiently large to promote slip on an array of secondary structures spanning the footprint of the modern geothermal activity. Slip on these secondary faults and fractures generates permeability through kinematic deformation and allows for transmission of fluids. Still, mineralization is expected to seal permeability along faults and fractures over time scales that are generally shorter than either earthquake recurrence intervals or the estimated life span of geothermal fields. This suggests that though stress perturbations resulting from fault slip are broadly important for defining the location and spatial extent of enhanced permeability at structural discontinuities, continual generation and maintenance of flow conduits throughout these areas are probably dependent on the deformation mechanism(s) affecting individual structures.
Breaking Ground.

ERIC Educational Resources Information Center

American School & University, 1998

1998-01-01

Explains the importance of using geothermal systems to reduce energy costs and improve heating and cooling in multipurpose schools. What geothermal systems are and their benefits in simplifying the school infrastructure and streamlining operating costs are highlighted. (GR)
Geothermal mineralized scales in the pipe system of the geothermal Piancastagnaio power plant (Mt. Amiata geothermal area): a key to understand the stibnite, cinnabarite and gold mineralization of Tuscany (central Italy)

NASA Astrophysics Data System (ADS)

Morteani, Giulio; Ruggieri, Giovanni; Möller, Peter; Preinfalk, Christine

2011-02-01

The CO2-rich geothermal fluids produced in the Piancastagnaio geothermal field (Mt. Amiata geothermal area, Southern Tuscany, Italy) show temperatures up to 360°C and pressures of about 200 bar at depths of around 3,500 m (Giolito, Ph.D. thesis, Università degli Studi di Firenze, Italy, pp 1-147, 2005). CaCO3- and/or SiO2-dominated scales are deposited in the pipes leading to the pressure and atmospheric separators of the geothermal wells. High content of metastibnite and/or stibnite in both calcite and silica scales and Sb contents of up to 50 mg/L in the fluids indicate their mineralising potential. The red or black colours of the scales depend on the predominance of red metastibnite or black stibnite, respectively. In our condensation experiments, as well as during deposition of the scales, metastibnite is the first Sb2S3 mineral to form. In a second stage, metastibnite is transformed to stibnite. During depressurization the Hg content of geothermal fluids partitions preferentially into the gas phase, whereas Sb and As remain in the liquid phase. This separation explains the often observed areal separation of Hg and Sb mineralization. The multistage deposition of Sb in the mining district of Tuscany is due to a periodic restoration of the permeability of the ore-bearing faults by microseismic events and subsequent host rock brecciation. The still ongoing microseismic events are induced by the accumulation of high-pressure CO2-rich fluids along faults followed by mechanical failure of the faults.
A hybrid geothermal energy conversion technology: Auxiliary heating of geothermally preheated water or CO2 - a potential solution for low-temperature resources

NASA Astrophysics Data System (ADS)

Saar, Martin; Garapati, Nagasree; Adams, Benjamin; Randolph, Jimmy; Kuehn, Thomas

2016-04-01

Safe, sustainable, and economic development of deep geothermal resources, particularly in less favourable regions, often requires employment of unconventional geothermal energy extraction and utilization methods. Often "unconventional geothermal methods" is synonymously and solely used as meaning enhanced geothermal systems, where the permeability of hot, dry rock with naturally low permeability at greater depths (4-6 km), is enhanced. Here we present an alternative unconventional geothermal energy utilization approach that uses low-temperature regions that are shallower, thereby drastically reducing drilling costs. While not a pure geothermal energy system, this hybrid approach may enable utilization of geothermal energy in many regions worldwide that can otherwise not be used for geothermal electricity generation, thereby increasing the global geothermal resource base. Moreover, in some realizations of this hybrid approach that generate carbon dioxide (CO2), the technology may be combined with carbon dioxide capture and storage (CCS) and CO2-based geothermal energy utilization, resulting in a high-efficiency (hybrid) geothermal power plant with a negative carbon footprint. Typically, low- to moderate-temperature geothermal resources are more effectively used for direct heat energy applications. However, due to high thermal losses during transport, direct use requires that the heat resource is located near the user. Alternatively, we show here that if such a low-temperature geothermal resource is combined with an additional or secondary energy resource, the power production is increased compared to the sum from two separate (geothermal and secondary fuel) power plants (DiPippo et al. 1978) and the thermal losses are minimized because the thermal energy is utilized where it is produced. Since Adams et al. (2015) found that using CO2 as a subsurface working fluid produces more net power than brine at low- to moderate-temperature geothermal resource conditions, we compare over a range of parameters the net power and efficiencies of hybrid geothermal power plants that use brine or CO2 as the subsurface working fluid, that are then heated further with a secondary energy source that is unspecified here. Parameters varied include the subsurface working fluid (brine vs. CO2), geothermal reservoir depth (2.5-4.5 km), and turbine inlet temperature (200-600°C) after auxiliary heating. The hybrid power plant is numerically modeled using an iterative coupling approach of TOUGH2-ECO2N/ECO2H (Pruess, 2004) for simulation of the subsurface reservoir and Engineering Equation Solver for well bore fluid flow and surface power plant performance. We find that hybrid power plants that are CO2-based (subsurface) systems produce more net power than the sum of the power produced by individual power plants at low turbine inlet temperatures and brine based systems produce more power at high turbine inlet temperatures. Specifically, our results indicate that geothermal hybrid plants that are CO2-based are more efficient than brine-based systems when the contribution of the geothermal resource energy is higher than 48%.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Clark, Corrie E.; Harto, Christopher B.; Schroeder, Jenna N.

This report is the third in a series of reports sponsored by the U.S. Department of Energy Geothermal Technologies Program in which a range of water-related issues surrounding geothermal power production are evaluated. The first report made an initial attempt at quantifying the life cycle fresh water requirements of geothermal power-generating systems and explored operational and environmental concerns related to the geochemical composition of geothermal fluids. The initial analysis of life cycle fresh water consumption of geothermal power-generating systems identified that operational water requirements consumed the vast majority of water across the life cycle. However, it relied upon limited operationalmore » water consumption data and did not account for belowground operational losses for enhanced geothermal systems (EGSs). A second report presented an initial assessment of fresh water demand for future growth in utility-scale geothermal power generation. The current analysis builds upon this work to improve life cycle fresh water consumption estimates and incorporates regional water availability into the resource assessment to improve the identification of areas where future growth in geothermal electricity generation may encounter water challenges. This report is divided into nine chapters. Chapter 1 gives the background of the project and its purpose, which is to assess the water consumption of geothermal technologies and identify areas where water availability may present a challenge to utility-scale geothermal development. Water consumption refers to the water that is withdrawn from a resource such as a river, lake, or nongeothermal aquifer that is not returned to that resource. The geothermal electricity generation technologies evaluated in this study include conventional hydrothermal flash and binary systems, as well as EGSs that rely on engineering a productive reservoir where heat exists, but where water availability or permeability may be limited. Chapter 2 describes the approach and methods for this work and identifies the four power plant scenarios evaluated: a 20-MW EGS binary plant, a 50-MW EGS binary plant, a 10-MW hydrothermal binary plant, and a 50-MW hydrothermal flash plant. The methods focus on (1) the collection of data to improve estimation of EGS stimulation volumes, aboveground operational consumption for all geothermal technologies, and belowground operational consumption for EGS; and (2) the mapping of the geothermal and water resources of the western United States to assist in the identification of potential water challenges to geothermal growth. Chapters 3 and 4 present the water requirements for the power plant life cycle. Chapter 3 presents the results of the current data collection effort, and Chapter 4 presents the normalized volume of fresh water consumed at each life cycle stage per lifetime energy output for the power plant scenarios evaluated. Over the life cycle of a geothermal power plant, from construction through 30 years of operation, the majority of water is consumed by plant operations. For the EGS binary scenarios, where dry cooling was assumed, belowground operational water loss is the greatest contributor depending upon the physical and operational conditions of the reservoir. Total life cycle water consumption requirements for air-cooled EGS binary scenarios vary between 0.22 and 1.85 gal/kWh, depending upon the extent of belowground operational water consumption. The air-cooled hydrothermal binary and flash plants experience far less fresh water consumption over the life cycle, at 0.04 gal/kWh. Fresh water requirements associated with air- cooled binary operations are primarily from aboveground water needs, including dust control, maintenance, and domestic use. Although wet-cooled hydrothermal flash systems require water for cooling, these plants generally rely upon the geofluid, fluid from the geothermal reservoir, which typically has high salinity and total dissolved solids concentration and is much warmer than normal groundwater sources, for their cooling water needs; thus, while there is considerable geofluid loss at 2.7 gal/kWh, fresh water consumption during operations is similar to that of aircooled binary systems. Chapter 5 presents the assessment of water demand for future growth in deployment of utility-scale geothermal power generation. The approach combines the life cycle analysis of geothermal water consumption with a geothermal supply curve according to resource type, levelized cost of electricity (LCOE), and potential growth scenarios. A total of 17 growth scenarios were evaluated. In general, the scenarios that assumed lower costs for EGSs as a result of learning and technological improvements resulted in greater geothermal potential, but also significantly greater water demand due to the higher water consumption by EGSs. It was shown, however, that this effect could be largely mitigated if nonpotable water sources were used for belowground operational water demands. The geographical areas that showed the highest water demand for most growth scenarios were southern and northern California, as well as most of Nevada. In addition to water demand by geothermal power production, Chapter 5 includes data on water availability for geothermal development areas. A qualitative analysis is included that identifies some of the basins where the limited availability of water is most likely to affect the development of geothermal resources. The data indicate that water availability is fairly limited, especially under drought conditions, in most of the areas with significant near- and medium-term geothermal potential. Southern California was found to have the greatest potential for water-related challenges with its combination of high geothermal potential and limited water availability. The results of this work are summarized in Chapter 6. Overall, this work highlights the importance of utilizing dry cooling systems for binary and EGS systems and minimizing fresh water consumption throughout the life cycle of geothermal power development. The large resource base for EGSs represents a major opportunity for the geothermal industry; however, depending upon geology, these systems can require large quantities of makeup water due to belowground reservoir losses. Identifying potential sources of compatible degraded or low-quality water for use for makeup injection for EGS and flash systems represents an important opportunity to reduce the impacts of geothermal development on fresh water resources. The importance of identifying alternative water sources for geothermal systems is heightened by the fact that a large fraction of the geothermal resource is located in areas already experiencing water stress. Chapter 7 is a glossary of the technical terms used in the report, and Chapters 8 and 9 provide references and a bibliography, respectively.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)

Aggarwal, J.K.; Palmer, M.R.

Boron isotope ratios have been determined in a variety of different geothermal waters from hydrothermal systems across Iceland. Isotope ratios from the high temperature meteoric water recharged systems reflect the isotope ratio of the host rocks without any apparent fractionation. Seawater recharged geothermal systems exhibit more positive {delta}{sup 11}B values than the meteoric water recharged geothermal systems. Water/rock ratios can be assessed from boron isotope ratios in the saline hydrothermal systems. Low temperature hydrothermal systems also exhibit more positive {delta}{sup 11}B than the high temperature systems, indicating fractionation of boron due to adsorption of the lighter isotope onto secondary minerals.more » Fractionation of boron in carbonate deposits may indicate the level of equilibrium attained within the systems.« less
Structural controls on a geothermal system in the Tarutung Basin, north central Sumatra

NASA Astrophysics Data System (ADS)

Nukman, Mochamad; Moeck, Inga

2013-09-01

The Sumatra Fault System provides a unique geologic setting to evaluate the influence of structural controls on geothermal activity. Whereas most of the geothermal systems in Indonesia are controlled by volcanic activity, geothermal systems at the Sumatra Fault System might be controlled by faults and fractures. Exploration strategies for these geothermal systems need to be verified because the typical pattern of heat source and alteration clays are missing so that conventional exploration with magnetotelluric surveys might not provide sufficient data to delineate favorable settings for drilling. We present field geological, structural and geomorphological evidence combined with mapping of geothermal manifestations to allow constraints between fault dynamics and geothermal activity in the Tarutung Basin in north central Sumatra. Our results indicate that the fault pattern in the Tarutung Basin is generated by a compressional stress direction acting at a high angle to the right-lateral Sumatra Fault System. NW-SE striking normal faults possibly related to negative flower structures and NNW-SSE to NNE-SSW oriented dilative Riedel shears are preferential fluid pathways whereas ENE-WSW striking faults act as barriers in this system. The dominant of geothermal manifestations at the eastern part of the basin indicates local extension due to clockwise block rotation in the Sumatra Fault System. Our results support the effort to integrate detailed field geological surveys to refined exploration strategies even in tropical areas where outcrops are limited.
A proposal to investigate higher enthalpy geothermal systems in the USA

NASA Astrophysics Data System (ADS)

Elders, W. A.

2013-12-01

After more than 50 years of development only ~3,400 MWe of electric power is currently being produced from geothermal resources in the USA. That is only about 0.33% of the country's total installed electrical capacity. In spite of the large demonstrated potential of geothermal resources, only ~2,500 MWe of new geothermal electrical capacity are under development, and the growth rate of this environmentally benign energy resource is overshadowed by the rapid increase in the installed capacity of wind and solar energy. Most of the new geothermal developments in the USA involve relatively small, moderate-temperature, geothermal systems. In contrast, development of higher enthalpy geothermal systems for power production has obvious advantages; specifically higher temperatures yield higher power outputs per well so that fewer wells are needed, leading to smaller environmental footprints for a given size of power plant. Disadvantages include that the fact that locations of suitable geothermal systems are restricted to young volcanic terrains, production of very high enthalpy fluids usually requires drilling deeper wells and may require enhanced geothermal (EGS) technology, and drilling deep into hot hostile environments is technologically challenging. However the potential for very favorable economic returns suggests that the USA should begin developing such a program. One approach to mitigating the cost issue is to form a consortium of industry, government and academia to share the costs and broaden the scope an investigation. An excellent example of such a collaboration is the Iceland Deep Drilling Project (IDDP) which is investigating the economic feasibility of producing electricity from supercritical geothermal reservoirs. This industry-government consortium planned to drill a deep well in the volcanic caldera of Krafla in NE Iceland. However drilling had to be terminated at 2.1 km depth when 900°C rhyolite magma flowed into the well. The resultant well was highly productive capable of generating >35 MWe from superheated steam at a well-head temperature of ~450°C. Plans for deep drilling to explore for deeper, much higher enthalpy, geothermal resources are already underway in the Taupo Volcanic Zone of New Zealand (Project HADES), and in northeast Japan the 'Beyond Brittle Project' (Project JBBP) is an ambitious program attempting to create an EGS reservoir in ~500oC rocks. However in the USA there is no comparable national program to develop such resources. There is a significant undeveloped potential for developing high-enthalpy geothermal systems in the western USA, Hawaii and Alaska. The purpose of this paper is to encourage the formation of a consortium to systematically explore, assess, and eventually develop such higher-enthalpy geothermal resources. Not only would this help develop large new sources of energy but it would permit scientific studies of pressure-temperature regimes not otherwise available for direct investigation, such as the coupling of magmatic and hydrothermal systems.
Subsurface Thermal Energy Storage for Improved Heating and Air Conditioning Efficiency

DTIC Science & Technology

2016-11-21

This project involved a field demonstration of subsurface thermal energy storage for improving the geothermal heat pump air conditioning efficiency... geothermal heat pump systems, undesirable heating of the ground may occur. This demonstration was performed at the MCAS, Beaufort, SC, where several...buildings with geothermal heat pump systems were exhibiting excessively high ground loop temperatures. These buildings were retrofitted with dry fluid
Stress heterogeneity above and within a deep geothermal reservoir: From borehole observations to geomechanical modelling

NASA Astrophysics Data System (ADS)

Seithel, Robin; Peters, Max; Lesueur, Martin; Kohl, Thomas

2017-04-01

Overpressured reservoir conditions, local stress concentrations or a locally rotated stress field can initiate substantial problems during drilling or reservoir exploitation. Increasing geothermal utilization in the Molasse basin area in S-Germany is faced with such problems of deeply seated reservoir sections. In several wells, radial fluid flow systems are interpreted as highly porous layers. However, in nearby wells a combination of linear fluid flow, local stress heterogeneities and structural geology hint to a rather fault dominated reservoir (Seithel et al. 2015). Due to missing knowledge of the stress magnitude, stress orientation and their coupling to reservoir response, we will present a THMC model of critical formations and the geothermal reservoir targeting nearby faults. In an area south of Munich, where several geothermal wells are constructed, such wells are interpreted and integrated into a 30 x 30 km simulated model area. One of the main objectives here is to create a geomechanical reservoir model in a thermo-mechanical manner in order to understand the coupling between reservoir heterogeneities and stress distributions. To this end, stress analyses of wellbore data and laboratory tests will help to calibrate a reliable model. In order to implement the complex geological structure of the studied wedge-shaped foreland basin, an automatic export of lithology, fault and borehole data (e.g. from Petrel) into a FE mesh is used. We will present a reservoir-scale model that considers thermo-mechanic effects and analyze their influence on reservoir deformation, fluid flow and stress concentration. We use the currently developed finite element application REDBACK (https://github.com/pou036/redback), inside the MOOSE framework (Poulet et al. 2016). We show that mechanical heterogeneities nearby fault zones and their orientation within the stress field correlate to fracture pattern, interpreted stress heterogeneities or variegated flow systems within the reservoir. REFERENCES Poulet, T.; Paesold, M.; Veveakis, M. (2016), Multi-Physics Modelling of Fault Mechanics Using REDBACK. A Parallel Open-Source Simulator for Tightly Coupled Problems. Rock Mechanics and Rock Engineering. doi: 10.1007/s00603-016-0927-y. Seithel, R.; Steiner, U.; Müller, B.I.R.; Hecht, Ch.; Kohl, T. (2015), Local stress anomaly in the Bavarian Molasse Basin, Geothermal Energy 3(1), p.77. doi:10.1186/s40517-014-0023-z
Advanced Horizontal Well Recirculation Systems for Geothermal Energy Recovery in Sedimentary and Crystalline Formations

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bruno, Mike S.; Detwiler, Russell L.; Lao, Kang

2012-12-13

There is increased recognition that geothermal energy resources are more widespread than previously thought, with potential for providing a significant amount of sustainable clean energy worldwide. Recent advances in drilling, completion, and production technology from the oil and gas industry can now be applied to unlock vast new geothermal resources, with some estimates for potential electricity generation from geothermal energy now on the order of 2 million megawatts. The primary objectives of this DOE research effort are to develop and document optimum design configurations and operating practices to produce geothermal power from hot permeable sedimentary and crystalline formations using advancedmore » horizontal well recirculation systems. During Phase I of this research project Terralog Technologies USA and The University of California, Irvine (UCI), have completed preliminary investigations and documentation of advanced design concepts for paired horizontal well recirculation systems, optimally configured for geothermal energy recovery in permeable sedimentary and crystalline formations of varying structure and material properties. We have also identified significant geologic resources appropriate for application of such technology. The main challenge for such recirculation systems is to optimize both the design configuration and the operating practices for cost-effective geothermal energy recovery. These will be strongly influenced by sedimentary formation properties, including thickness and dip, temperature, thermal conductivity, heat capacity, permeability, and porosity; and by working fluid properties.« less
The Colorado School of Mines Nevada geothermal study

NASA Technical Reports Server (NTRS)

Keller, G. V.; Grose, L. T.; Crewpson, R. A.

1974-01-01

Geothermal systems in the Basin and Range Province of the western United States probably differ in many respects from geothermal systems already discovered in other parts of the world because of the unique tectonic setting. To investigate this, a study of the geothermal occurrences at Fly Ranch, approximately 100 miles north of Reno, Nevada, has been undertaken. Ample evidence for a geothermal system exists in this area, including the surface expression of heat flow in the form of hot springs, an extensive area of low electrical resistivity, and a high level of seismicity along faults bounding the thermal area. However, geophysical and geological studies have not yet provided evidence for a local heat source at depth. Additional detailed geophysical and geological studies, as well as drilling, must be completed before the geothermal system can be described fully.
Play-fairway analysis for geothermal resources and exploration risk in the Modoc Plateau region

USGS Publications Warehouse

Siler, Drew; Zhang, Yingqi; Spycher, Nicolas F.; Dobson, Patrick; McClain, James S.; Gasperikova, Erika; Zierenberg, Robert A.; Schiffman, Peter; Ferguson, Colin; Fowler, Andrew; Cantwell, Carolyn

2017-01-01

The region surrounding the Modoc Plateau, encompassing parts of northeastern California, southern Oregon, and northwestern Nevada, lies at an intersection between two tectonic provinces; the Basin and Range province and the Cascade volcanic arc. Both of these provinces have substantial geothermal resource base and resource potential. Geothermal systems with evidence of magmatic heat, associated with Cascade arc magmatism, typify the western side of the region. Systems on the eastern side of the region appear to be fault controlled with heat derived from high crustal heat flow, both of which are typical of the Basin and Range. As it has the potential to host Cascade arc-type geothermal resources, Basin and Range-type geothermal resources, and/or resources with characteristics of both provinces, and because there is relatively little current development, the Modoc Plateau region represents an intriguing potential for undiscovered geothermal resources. It remains unclear however, what specific set(s) of characteristics are diagnostic of Modoc-type geothermal systems and how or if those characteristics are distinct from Basin and Range-type or Cascade arc-type geothermal systems. In order to evaluate the potential for undiscovered geothermal resources in the Modoc area, we integrate a wide variety of existing data in order to evaluate geothermal resource potential and exploration risk utilizing ‘play-fairway’ analysis. We consider that the requisite parameters for hydrothermal circulation are: 1) heat that is sufficient to drive circulation, and 2) permeability that is sufficient to allow for fluid circulation in the subsurface. We synthesize data that indicate the extent and distribution of these parameters throughout the Modoc region. ‘Fuzzy logic’ is used to incorporate expert opinion into the utility of each dataset as an indicator of either heat or permeability, and thus geothermal favorability. The results identify several geothermal prospects, areas that are highly favorable for the occurrence of both heat and permeability. These are also areas where there is sufficient data coverage, quality, and consistency that the exploration risk is relatively low. These unknown, undeveloped, and under-developed prospects are well-suited for continued exploration efforts. The results also indicate to what degree the two ‘play-types,’ i.e. Cascade arc-type or Basin and Range-type, apply to each of the geothermal prospects, a useful guide in exploration efforts.
Self-Protecting Security for Assured Information Sharing

DTIC Science & Technology

2015-08-29

by Author Sophia Novitzky (Senior), Virginia Tech Mahalia Sapp (Senior), Virginia Tech Performance Sensitivity in Vertical Geothermal Energy...Harvesting Systems 9:15 AM, Annapolis Room, Student Center Residential geothermal energy systems have the potential to provide a cost-effective, low

Method for inhibiting silica precipitation and scaling in geothermal flow systems

DOEpatents

Harrar, J.E.; Lorensen, L.E.; Locke, F.E.

1980-06-13

A method for inhibiting silica scaling and precipitation in geothermal flow systems by on-line injection of low concentrations of cationic nitrogen-containing compounds, particularly polymeric imines, polymeric amines, and quaternary ammonium compounds is described.
The Pawsey Supercomputer geothermal cooling project

NASA Astrophysics Data System (ADS)

Regenauer-Lieb, K.; Horowitz, F.; Western Australian Geothermal Centre Of Excellence, T.

2010-12-01

The Australian Government has funded the Pawsey supercomputer in Perth, Western Australia, providing computational infrastructure intended to support the future operations of the Australian Square Kilometre Array radiotelescope and to boost next-generation computational geosciences in Australia. Supplementary funds have been directed to the development of a geothermal exploration well to research the potential for direct heat use applications at the Pawsey Centre site. Cooling the Pawsey supercomputer may be achieved by geothermal heat exchange rather than by conventional electrical power cooling, thus reducing the carbon footprint of the Pawsey Centre and demonstrating an innovative green technology that is widely applicable in industry and urban centres across the world. The exploration well is scheduled to be completed in 2013, with drilling due to commence in the third quarter of 2011. One year is allocated to finalizing the design of the exploration, monitoring and research well. Success in the geothermal exploration and research program will result in an industrial-scale geothermal cooling facility at the Pawsey Centre, and will provide a world-class student training environment in geothermal energy systems. A similar system is partially funded and in advanced planning to provide base-load air-conditioning for the main campus of the University of Western Australia. Both systems are expected to draw ~80-95 degrees C water from aquifers lying between 2000 and 3000 meters depth from naturally permeable rocks of the Perth sedimentary basin. The geothermal water will be run through absorption chilling devices, which only require heat (as opposed to mechanical work) to power a chilled water stream adequate to meet the cooling requirements. Once the heat has been removed from the geothermal water, licensing issues require the water to be re-injected back into the aquifer system. These systems are intended to demonstrate the feasibility of powering large-scale air-conditioning systems from the direct use of geothermal power from Hot Sedimentary Aquifer (HSA) systems. HSA systems underlie many of the world's population centers, and thus have the potential to offset a significant fraction of the world's consumption of electrical power for air-conditioning.
Multidisciplinary research of geothermal modeling

NASA Astrophysics Data System (ADS)

-Ing. Ulvi Arslan, Univ., ., Dr. _., Prof.; Heiko Huber, Dipl.-Ing.

2010-05-01

KEYWORDS Geothermal sciences, geothermics, research, theory and application, numerical calculation, geothermal modeling, Technical University Darmstadt, Ministry of Economics and Technology (BMWi) INTRODUCTION In times of global warming renewable, green energies are getting more and more important. The development of application of geothermal energy as a part of renewable energies in Germany is a multidisciplinary process of fast growing research and improvements. Geothermal energy is the energy, which is stored below earth's surface. The word geothermal derives from the Greek words geo (earth) and thermos (heat), so geothermal is a synonym to earth heat. Geothermal energy is one of the auspicious renewable energies. In average the temperature increases 3°C every 100 m of depth, which is termed as geothermal gradient. Therefore 99 percent of our planet is hotter than 1.000°C, while 99 percent of that last percent is even hotter than 100°C. Already in a depth of about 1 kilometer temperatures of 35 - 40°C can be achieved. While other renewable energies arise less or more from the sun, geothermal energy sources its heat from the earth's interior, which is caused mostly by radioactive decay of persistent isotopes. This means a possibility of a base-loadable form of energy supply. Especially efficient is the use of deep geothermal energy of high-enthalpie reservoirs, which means a high energy potential in low depths. In Germany no high-enthalpie reservoirs are given. To use the given low-enthalpie potential and to generate geothermal power efficiently inventions and improvements need to be performed. An important part of geothermal progresses is performed by universities with multidisciplinary research of geothermal modeling. Especially in deep geothermal systems numerical calculations are essential for a correct dimensioning of the geothermal system. Therefore German universities and state aided organizations are developing numerical programs for a detailed use of application on geothermal systems. The history of this multidisciplinary research of geothermal modeling performed by German universities is shown in this paper. Outstanding geothermal research programs of German universities and state aided organizations (BGR, LBEG, GGA) are pointed out. Actual geothermal modeling programs based on the Finite-Element-Method or the Finite-Differences-Method as well as analytical programs are introduced. National and international geothermal projects supported by German universities and state aided organizations are described. Examples of supervised shallow and deep geothermal systems are given. Actually the Technical University Darmstadt is performing a research program supported by a national organization, the Ministry of Economics and Technology (BMWi). Main aim of this research program titled experimental investigation for the verification of a Finite-Element-Multiphase-Model is to analyze the subsoil as a three-phases-model with separated consideration of conduction, convection and advection and their subsequent interaction. The latest developments of numerical projects as well as the actual state of the before mentioned research program are pointed out in the paper. REFERENCES Quick, H., Arslan, U., Meißner, S., Michael, J. 2007. Deep foundations and geothermal energy - a multi-purpose solution, IFHS: 8. International conference on multi-purpose high-rise towers and tall buildings, Abu Dhabi, 2007 Arslan, U. and Huber, H. 2008. Application of geothermal energy. University of Istanbul, Yapistanbul No. 3 / 2008, Turkey, 2008 Quick, Q., Michael, J., Arslan, U., Huber, H. 2010. History of International Geothermal Power Plants and Geothermal Projects in Germany, Proceedings World Geothermal Congress 2010 Bali, Indonesia, 25-29 April 2010 Arslan, U., Huber, H. 2010. Education of Geothermal Sciences in Germany as part of an application orientated research, Proceedings European Civil Engineering Education and Training (EUCEET III) Special Volume, 2010
Army Net Zero Prove Out. Net Zero Energy Best Practices

DTIC Science & Technology

2014-11-18

energy which is then used to drive a heat engine to generate electrical power. Geothermal Power – These systems use thermal energy generated and...stored in the earth as a generating source for electricity. Several pilot installations are investigating this technology by conducting geothermal ...concentrate solar thermal energy which is then used to drive a heat engine to generate electrical power. • Geothermal Power - These systems use thermal energy
WESTERN ENERGY RESOURCES AND THE ENVIRONMENT: GEOTHERMAL ENERGY

EPA Science Inventory

Geothermal energy--from subsurface heat sources created by the underlying geologic configuration of the earth--is addressed, from an environmental research and development perspective. The report covers various geothermal energy systems, which serve as present or potential energy...
Geologic controls on supercritical geothermal resources above magmatic intrusions.

PubMed

Scott, Samuel; Driesner, Thomas; Weis, Philipp

2015-07-27

A new and economically attractive type of geothermal resource was recently discovered in the Krafla volcanic system, Iceland, consisting of supercritical water at 450 °C immediately above a 2-km deep magma body. Although utilizing such supercritical resources could multiply power production from geothermal wells, the abundance, location and size of similar resources are undefined. Here we present the first numerical simulations of supercritical geothermal resource formation, showing that they are an integral part of magma-driven geothermal systems. Potentially exploitable resources form in rocks with a brittle-ductile transition temperature higher than 450 °C, such as basalt. Water temperatures and enthalpies can exceed 400 °C and 3 MJ kg(-1), depending on host rock permeability. Conventional high-enthalpy resources result from mixing of ascending supercritical and cooler surrounding water. Our models reproduce the measured thermal conditions of the resource discovered at Krafla. Similar resources may be widespread below conventional high-enthalpy geothermal systems.
Method for inhibiting silica precipitation and scaling in geothermal flow systems

DOEpatents

Harrar, Jackson E.; Lorensen, Lyman E.; Locke, Frank E.

1982-01-01

A method for inhibiting silica scaling and precipitation in geothermal flow systems by on-line injection of low concentrations of cationic nitrogen-containing compounds, particularly polymeric imines, polymeric amines, and quaternary ammonium compounds.
Geologic map of upper Eocene to Holocene volcanic and related rocks in the Cascade Range, Washington

USGS Publications Warehouse

Smith, James G.

1993-01-01

For geothermal reasons, the maps emphasize Quaternary volcanic rocks. Large igneous-related geothermal systems that have high temperatures are associated with Quaternary volcanic fields, and geothermal potential declines rapidly as age increases (Smith and Shaw, 1975). Most high-grade recoverable geothermal energy is likely to be associated with silicic volcanism less than 1 Ma. Lower grade (= lower temperature) geothermal resources may be associated with somewhat older rocks; however, volcanic rocks older than about 2 Ma are unlikely geothermal targets (Smith and Shaw, 1975).
Sulfur isotopes in Icelandic thermal fluids

NASA Astrophysics Data System (ADS)

Gunnarsson-Robin, Jóhann; Stefánsson, Andri; Ono, Shuhei; Torssander, Peter

2017-10-01

Multiple sulfur isotope compositions of thermal fluids from Iceland were measured in order to evaluate the sources and reactions of sulfur and sulfur isotope fractionation in geothermal systems at Icelandic divergent plate boundaries, characterized by MORB-like basalts. The geothermal systems studied had a wide range of reservoir temperatures of 56-296 °C and Cl concentrations of 18-21,000 ppm. Dissolved sulfide (∑ S- II) and SO4 concentrations in liquid water measured < 0.01-165 ppm and 1.3-300 ppm, respectively, and H2S(g) concentrations in the vapor 4.9-2000 ppm. The δ34S and Δ33S values for different phases and oxidation states were highly variable: δ34S∑ S- II = - 11.6 to 10.5‰ (n = 99), Δ33S∑ S- II = - 0.12 to 0.00‰ (n = 45), δ34SSO4 = - 1.0 to 24.9‰ (n = 125), Δ33SSO4 = - 0.04 to 0.02‰ (n = 50), δ34SH2S(g) = - 2.6 to 5.9‰ (n = 112) and Δ33SH2S(g) = - 0.03 to 0.00‰ (n = 56). The multiple sulfur isotope values of the thermal fluids are interpreted to reflect various sources of sulfur in the fluids, as well as isotope fractionation occurring within the geothermal systems associated with fluid-rock interaction, boiling and oxidation and reduction reactions. The results of isotope geochemical modeling demonstrate that the sources of S- II in the thermal fluid are leaching of basalt (MORB) and seawater SO4 reduction for saline systems with insignificant magma gas input, and that the observed ranges of δ34S and Δ33S for ∑ S- II and H2S(g) reflect isotope fractionation between minerals and aqueous and gaseous species upon fluid-rock interaction and boiling. The sources of SO4 are taken to be multiple, including oxidation of S- II originating from basalt, leaching of SVI from the basalts and the seawater itself in the case of saline systems. In low-temperature fluids, the δ34S and Δ33S values reflect the various sources of sulfur. For high-temperature fluids, fluid-rock interaction, ∑ S- II oxidation and SO4 reduction and sulfide and sulfate mineral formation result in a large range of δ34S and Δ33S values for ∑ S- II and SO4 in the fluids, highlighting the importance and effects of chemical reactions on the isotope systematics of reactive elements like sulfur. Such effects needed to be quantified in order to reveal the various sources of an element.
Isotopic and noble gas geochemistry in geothermal research

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kennedy, B.M.; DePaolo, D.J.

1997-12-31

The objective of this program is to provide, through isotopic analyses of fluids, fluid inclusions, and rocks and minerals coupled with improved methods for geochemical data analysis, needed information regarding sources of geothermal heat and fluids, the spatial distribution of fluid types, subsurface flow, water-rock reaction paths and rates, and the temporal evolution of geothermal systems. Isotopic studies of geothermal fluids have previously been limited to the light stable isotopes of H, C, and O. However, other isotopic systems such as the noble gases (He, Ne, Ar, Kr and Xe) and reactive elements (e.g. B, N, S, Sr and Pb)more » are complementary and may even be more important in some geothermal systems. The chemistry and isotopic composition of a fluid moving through the crust will change in space and time in response to varying chemical and physical parameters or by mixing with additional fluids. The chemically inert noble gases often see through these variations, making them excellent tracers for heat and fluid sources. Whereas, the isotopic compositions of reactive elements are useful tools in characterizing water-rock interaction and modeling the movement of fluids through a geothermal reservoir.« less
Assessment of Moderate- and High-Temperature Geothermal Resources of the United States

USGS Publications Warehouse

Williams, Colin F.; Reed, Marshall J.; Mariner, Robert H.; DeAngelo, Jacob; Galanis, S. Peter

2008-01-01

Scientists with the U.S. Geological Survey (USGS) recently completed an assessment of our Nation's geothermal resources. Geothermal power plants are currently operating in six states: Alaska, California, Hawaii, Idaho, Nevada, and Utah. The assessment indicates that the electric power generation potential from identified geothermal systems is 9,057 Megawatts-electric (MWe), distributed over 13 states. The mean estimated power production potential from undiscovered geothermal resources is 30,033 MWe. Additionally, another estimated 517,800 MWe could be generated through implementation of technology for creating geothermal reservoirs in regions characterized by high temperature, but low permeability, rock formations.
A new idea: The possibilities of offshore geothermal system in Indonesia marine volcanoes

NASA Astrophysics Data System (ADS)

Rahat Prabowo, Teguh; Fauziyyah, Fithriyani; Suryantini; Bronto, Sutikno

2017-12-01

High temperature geothermal systems in Indonesia are commonly associated with volcanic systems. It is believed that volcanoes are acting as the heat source for a geothermal system. Right now, most of the operating geothermal fields in the world are assosiating with volcanic settings which known as the conventional geothermal system. Volcanoes are created in active tectonic zone such as collision zone and MOR (mid oceanic ridge). The later is the one which formed the marine volcanoes on the sea floor. The advances of today’s technology in geothermal energy has created many ideas regarding a new kind of geothermal system, including the ideas of developing the utilization of marine volcanoes. These marine volcanoes are predicted to be hotter than the land system due to the shorter distance to the magma chamber. Seamounts like NEC, Banua Wuhu, and Kawio Barat in Indonesia Sea are good spots to be studied. Methods such as remote sensing using NOAA images, sonar, and MAPR are commonly used, eventhough these would be more accurate with more detailed techniques. This has become the challenge for all geothermal scientists to overcome for a better study result.
Three dimensional images of geothermal systems: local earthquake P-wave velocity tomography at the Hengill and Krafla geothermal areas, Iceland, and The Geysers, California

USGS Publications Warehouse

Julian, B.R.; Prisk, A.; Foulger, G.R.; Evans, J.R.; ,

1993-01-01

Local earthquake tomography - the use of earthquake signals to form a 3-dimensional structural image - is now a mature geophysical analysis method, particularly suited to the study of geothermal reservoirs, which are often seismically active and severely laterally inhomogeneous. Studies have been conducted of the Hengill (Iceland), Krafla (Iceland) and The Geysers (California) geothermal areas. All three systems are exploited for electricity and/or heat production, and all are highly seismically active. Tomographic studies of volumes a few km in dimension were conducted for each area using the method of Thurber (1983).
DOE Office of Scientific and Technical Information (OSTI.GOV)

Walters, M.A.; Sternfeld, J.N.; Haizlip, J.R.

A high-temperature, vapor-dominated reservoir underlies a portion of the northwest Geysers area, Sonoma County, California. The high-temperature reservoir (HTR) is defined by flowing fluid temperatures exceeding 500/sup 0/F, rock temperatures apparently exceeding 600/sup 0/F, and steam enthalpies of about 1320 Btu/lb. The HTR in the northwest Geysers is probably a deep, evolving system in contrast to the shallower, leaky, and mature steam reservoir(s) in the central and southeastern portions of the field. Before natural venting and nearby production caused pressures to decline, the HTR was a liquid-dominated system with some connate water - the connate water being the source ofmore » the high gas contents, chloride, and unique isotopic composition relative to steam from a typical Geysers reservoir. Therefore, the present boundary between the typical reservoir and HTR is a transient, thermodynamic condition due to the recent evolution of a vapor-dominated zone from a liquid-dominated zone that has yet to cool down. It also demarks a previous liquid-to-vapor interface. Pressure in the two reservoirs is essentially the same because they are in communication with each other. In other words, the temperature change in the HTR is lagging (behind) the pressure change.« less
Low Temperature Geothermal Resource Assessment for Membrane Distillation Desalination in the United States

DOE Office of Scientific and Technical Information (OSTI.GOV)

Akar, Sertac; Turchi, Craig

Substantial drought and declines in potable groundwater in the United States over the last decade has increased the demand for fresh water. Desalination of saline water such as brackish surface or groundwater, seawater, brines co-produced from oil and gas operations, industrial wastewater, blow-down water from power plant cooling towers, and agriculture drainage water can reduce the volume of water that requires disposal while providing a source of high-quality fresh water for industrial or commercial use. Membrane distillation (MD) is a developing technology that uses low-temperature thermal energy for desalination. Geothermal heat can be an ideal thermal-energy source for MD desalinationmore » technology, with a target range of $1/m3 to $2/m3 for desalinated water depending on the cost of heat. Three different cases were analyzed to estimate levelized cost of heat (LCOH) for integration of MD desalination technology with low-grade geothermal heat: (1) residual heat from injection brine at a geothermal power plant, (2) heat from existing underutilized low-temperature wells, and (3) drilling new wells for low-temperature resources. The Central and Western United States have important low-temperature (<90 degrees C) geothermal resource potential with wide geographic distribution, but these resources are highly underutilized because they are inefficient for power production. According to the USGS, there are 1,075 identified low temperature hydrothermal systems, 55 low temperature sedimentary systems and 248 identified medium to high temperature geothermal systems in the United States. The estimated total beneficial heat potential from identified low temperature hydrothermal geothermal systems and residual beneficial heat from medium to high temperature systems is estimated as 36,300 MWth, which could theoretically produce 1.4 to 7 million m3/day of potable water, depending on desalination efficiency.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)

Bodvarsson, G.S.

The use of numerical models for the evaluation of the generating potential of high temperature geothermal fields has increased rapidly in recent years. In the present paper a unified numerical approach to the modeling of geothermal systems is discussed and the results of recent modeling of the Krafla geothermal field in Iceland and the Olkaria, Kenya, are described. Emphasis is placed on describing the methodology using examples from the two geothermal fields.
Play-fairway analysis for geothermal exploration: Examples from the Great Basin, western USA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siler, Drew L; Faulds, James E

2013-10-27

Elevated permeability within fault systems provides pathways for circulation of geothermal fluids. Future geothermal development depends on precise and accurate location of such fluid flow pathways in order to both accurately assess geothermal resource potential and increase drilling success rates. The collocation of geologic characteristics that promote permeability in a given geothermal system define the geothermal ‘fairway’, the location(s) where upflow zones are probable and where exploration efforts including drilling should be focused. We define the geothermal fairway as the collocation of 1) fault zones that are ideally oriented for slip or dilation under ambient stress conditions, 2) areas withmore » a high spatial density of fault intersections, and 3) lithologies capable of supporting dense interconnected fracture networks. Areas in which these characteristics are concomitant with both elevated temperature and fluids are probable upflow zones where economic-scale, sustainable temperatures and flow rates are most likely to occur. Employing a variety of surface and subsurface data sets, we test this ‘play-fairway’ exploration methodology on two Great Basin geothermal systems, the actively producing Brady’s geothermal system and a ‘greenfield’ geothermal prospect at Astor Pass, NV. These analyses, based on 3D structural and stratigraphic framework models, reveal subsurface characteristics about each system, well beyond the scope of standard exploration methods. At Brady’s, the geothermal fairways we define correlate well with successful production wells and pinpoint several drilling targets for maintaining or expanding production in the field. In addition, hot-dry wells within the Brady’s geothermal field lie outside our defined geothermal fairways. At Astor Pass, our play-fairway analysis provides for a data-based conceptual model of fluid flow within the geothermal system and indicates several targets for exploration drilling.« less
The significance of "geothermal microzonation" for the correct planning of low-grade source geothermal systems

NASA Astrophysics Data System (ADS)

Viccaro, Marco; Pezzino, Antonino; Belfiore, Giuseppe Maria; Campisano, Carlo

2016-04-01

Despite the environmental-friendly energy systems are solar thermal technologies, photovoltaic and wind power, other advantageous technologies exist, although they have not found wide development in countries such as Italy. Given the almost absent environmental impact and the rather favorable cost/benefit ratio, low-enthalpy geothermal systems are, however, likely to be of strategic importance also in Italy during the next years. The importance of geology for a sustainable exploitation of the ground through geothermal systems from low-grade sources is becoming paramount. Specifically, understanding of the lithological characteristics of the subsurface along with structures and textures of rocks is essential for a correct planning of the probe/geo-exchanger field and their associated ground source heat pumps. The complex geology of Eastern Sicily (Southern Italy), which includes volcanic, sedimentary and metamorphic units over limited extension, poses the question of how thermal conductivity of rocks is variable at the scale of restricted areas (even within the same municipality). This is the innovative concept of geothermal microzonation, i.e., how variable is the geothermal potential as a function of geology at the microscale. Some pilot areas have been therefore chosen to test how the geological features of the subsurface can influence the low-enthalpy geothermal potential of an area. Our geologically based evaluation and micro-zonation of the low-grade source geothermal potential of the selected areas have been verified to be fundamental for optimization of all the main components of a low-enthalpy geothermal system. Saving realization costs and limiting the energy consumption through correct sizing of the system are main ambitions to have sustainable development of this technology with intensive utilization of the subsurface. The variegated territory of countries such as Italy implies that these goals can be only reached if, primarily, the geological features of the shallow subsurface (i.e., chemical-physical characteristics of rocks and fluids of the first 100 m below the ground) are appropriately constrained.
Egypt/United States cooperative energy assessment. Volume II, Annex 1. Energy resources of Egypt

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1979-04-01

This report contains the findings and recommendations of the US Geological Survey geologists assigned to survey Egypts indigenous energy resources. Data on oil and gas, coal and oil shale, uranium and thorium, geothermal energy, water resources, and energy related minerals are presented. Thirty-nine oil and gas fields have been discovered in Egypt, proven reserves of oil were estimated to be 1,559,000,000 barrels in 1976. The Egyptian government hopes to attain a production rate of 1 million barrels a day in 1982. While the Gulf of Suez basin holds the most immediate prospects, the most promising frontier regions are the unexploredmore » broad expanses of the Western Desert, the Nile Basin and the Northern Sinai while oil shales have been found in Egypt, they are only 10 to 15 feet thick and their hydrocarbon content is low. Recovery would not be economic. Coal deposits contain reserves estimated at 95 to 112 million tons. Only 1 deposit is deemed workable under present conditions of technology and economy. No uranium and thorium are being produced however geological conditions appear favorable for finding uranium deposits using appropriate programs of prospecting, exploration and development. The potential for development of low-level sources of geothermal energy in Egypt is good; there is no evidence of a high-temperature source or a vapor-dominated system. The Nile is the primary source of water. In the western desert, the Nubian aquifer supplies water for irrigation. Energy related minerals are generally found in uneconomic concentrations or not at all. However, deposits of material used in cement making and some iron ore for steel making are available. Deposits of manganese may become available upon return of the Sinai to Egypt. 44 figures, 24 tables. (DMC)« less
Helical screw expander evaluation project

NASA Technical Reports Server (NTRS)

Mckay, R.

1982-01-01

A one MW helical rotary screw expander power system for electric power generation from geothermal brine was evaluated. The technology explored in the testing is simple, potentially very efficient, and ideally suited to wellhead installations in moderate to high enthalpy, liquid dominated field. A functional one MW geothermal electric power plant that featured a helical screw expander was produced and then tested with a demonstrated average performance of approximately 45% machine efficiency over a wide range of test conditions in noncondensing, operation on two-phase geothermal fluids. The Project also produced a computer equipped data system, an instrumentation and control van, and a 1000 kW variable load bank, all integrated into a test array designed for operation at a variety of remote test sites. Data are presented for the Utah testing and for the noncondensing phases of the testing in Mexico. Test time logged was 437 hours during the Utah tests and 1101 hours during the Mexico tests.

Environmental control technology (ECT) for geothermal processes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Katz, G.

1982-01-01

The objectives of the environmental control technology (ECT) program are to develop research priorities, research new and alternative technologies and to improve economics and performance of ECT systems. The Interagency Geothermal Coordinating Council, Environmental Control Panel developed priorities and obtained industry input during 1980. H/sub 2/S controls, injection monitoring, solid waste characterization and control and subsidence were reviewed as high priority while noise controls were considered low priority. Since geothermal technology is still developing there is a need to continue researching new and alternative ECT. Often ECT systems must be designed for site specific applications and need modification for usemore » of other sites. Most of the US geothermal experience is found at the Geysers, California where H/sub 2/S abatement is required. Various systems have been tested with mixed results. The bottom line is that the economics and performance of H/sub 2/S abatement systems are less than desirable.« less
3-Dimensional Geologic Modeling Applied to the Structural Characterization of Geothermal Systems: Astor Pass, Nevada, USA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siler, Drew L; Faulds, James E; Mayhew, Brett

2013-04-16

Geothermal systems in the Great Basin, USA, are controlled by a variety of fault intersection and fault interaction areas. Understanding the specific geometry of the structures most conducive to broad-scale geothermal circulation is crucial to both the mitigation of the costs of geothermal exploration (especially drilling) and to the identification of geothermal systems that have no surface expression (blind systems). 3-dimensional geologic modeling is a tool that can elucidate the specific stratigraphic intervals and structural geometries that host geothermal reservoirs. Astor Pass, NV USA lies just beyond the northern extent of the dextral Pyramid Lake fault zone near the boundarymore » between two distinct structural domains, the Walker Lane and the Basin and Range, and exhibits characteristics of each setting. Both northwest-striking, left-stepping dextral faults of the Walker Lane and kinematically linked northerly striking normal faults associated with the Basin and Range are present. Previous studies at Astor Pass identified a blind geothermal system controlled by the intersection of west-northwest and north-northwest striking dextral-normal faults. Wells drilled into the southwestern quadrant of the fault intersection yielded 94°C fluids, with geothermometers suggesting a maximum reservoir temperature of 130°C. A 3-dimensional model was constructed based on detailed geologic maps and cross-sections, 2-dimensional seismic data, and petrologic analysis of the cuttings from three wells in order to further constrain the structural setting. The model reveals the specific geometry of the fault interaction area at a level of detail beyond what geologic maps and cross-sections can provide.« less
Neutron Radiography of Fluid Flow for Geothermal Energy Research

NASA Astrophysics Data System (ADS)

Bingham, P.; Polsky, Y.; Anovitz, L.; Carmichael, J.; Bilheux, H.; Jacobsen, D.; Hussey, D.

Enhanced geothermal systems seek to expand the potential for geothermal energy by engineering heat exchange systems within the earth. A neutron radiography imaging method has been developed for the study of fluid flow through rock under environmental conditions found in enhanced geothermal energy systems. For this method, a pressure vessel suitable for neutron radiography was designed and fabricated, modifications to imaging instrument setups were tested, multiple contrast agents were tested, and algorithms developed for tracking of flow. The method has shown success for tracking of single phase flow through a manufactured crack in a 3.81 cm (1.5 inch) diameter core within a pressure vessel capable of confinement up to 69 MPa (10,000 psi) using a particle tracking approach with bubbles of fluorocarbon-based fluid as the ;particles; and imaging with 10 ms exposures.
Geothermal Geodatabase for Wagon Wheel Hot Springs, Mineral County, Colorado

DOE Data Explorer

Richard Zehner

2012-11-01

This geodatabase was built to cover several geothermal targets developed by Flint Geothermal in 2012 during a search for high-temperature systems that could be exploited for electric power development. Several of the thermal springs at Wagon Wheel Gap have geochemistry and geothermometry values indicative of high-temperature systems. Datasets include: 1. Results of reconnaissance shallow (2 meter) temperature surveys 2. Air photo lineaments 3. Groundwater geochemistry 4. Power lines 5. Georeferenced geologic map of Routt County 6. Various 1:24,000 scale topographic maps
Analysis of Geothermal Pathway in the Metamorphic Area, Northeastern Taiwan

NASA Astrophysics Data System (ADS)

Wang, C.; Wu, M. Y.; Song, S. R.; Lo, W.

2016-12-01

A quantitative measure by play fairway analysis in geothermal energy development is an important tool that can present the probability map of potential resources through the uncertainty studies in geology for early phase decision making purpose in the related industries. While source, pathway, and fluid are the three main geologic factors in traditional geothermal systems, identifying the heat paths is critical to reduce drilling cost. Taiwan is in East Asia and the western edge of Pacific Ocean, locating on the convergent boundary of Eurasian Plate and Philippine Sea Plate with many earthquake activities. This study chooses a metamorphic area in the western corner of Yi-Lan plain in northeastern Taiwan with high geothermal potential and several existing exploration sites. Having high subsurface temperature gradient from the mountain belts, and plenty hydrologic systems through thousands of millimeters annual precipitation that would bring up heats closer to the surface, current geothermal conceptual model indicates the importance of pathway distribution which affects the possible concentration of extractable heat location. The study conducts surface lineation analysis using analytic hierarchy process to determine weights among various fracture types for their roles in geothermal pathways, based on the information of remote sensing data, published geologic maps and field work measurements, to produce regional fracture distribution probability map. The results display how the spatial distribution of pathways through various fractures could affect geothermal systems, identify the geothermal plays using statistical data analysis, and compare against the existing drilling data.
Geologic controls on supercritical geothermal resources above magmatic intrusions

PubMed Central

Scott, Samuel; Driesner, Thomas; Weis, Philipp

2015-01-01

A new and economically attractive type of geothermal resource was recently discovered in the Krafla volcanic system, Iceland, consisting of supercritical water at 450 °C immediately above a 2-km deep magma body. Although utilizing such supercritical resources could multiply power production from geothermal wells, the abundance, location and size of similar resources are undefined. Here we present the first numerical simulations of supercritical geothermal resource formation, showing that they are an integral part of magma-driven geothermal systems. Potentially exploitable resources form in rocks with a brittle–ductile transition temperature higher than 450 °C, such as basalt. Water temperatures and enthalpies can exceed 400 °C and 3 MJ kg−1, depending on host rock permeability. Conventional high-enthalpy resources result from mixing of ascending supercritical and cooler surrounding water. Our models reproduce the measured thermal conditions of the resource discovered at Krafla. Similar resources may be widespread below conventional high-enthalpy geothermal systems. PMID:26211617
Technology Development and Field Trials of EGS Drilling Systems at Chocolate Mountain

DOE Data Explorer

Steven Knudsen

2012-01-01

Polycrystalline diamond compact (PDC) bits are routinely used in the oil and gas industry for drilling medium to hard rock but have not been adopted for geothermal drilling, largely due to past reliability issues and higher purchase costs. The Sandia Geothermal Research Department has recently completed a field demonstration of the applicability of advanced synthetic diamond drill bits for production geothermal drilling. Two commercially-available PDC bits were tested in a geothermal drilling program in the Chocolate Mountains in Southern California. These bits drilled the granitic formations with significantly better Rate of Penetration (ROP) and bit life than the roller cone bit they are compared with. Drilling records and bit performance data along with associated drilling cost savings are presented herein. The drilling trials have demonstrated PDC bit drilling technology has matured for applicability and improvements to geothermal drilling. This will be especially beneficial for development of Enhanced Geothermal Systems whereby resources can be accessed anywhere within the continental US by drilling to deep, hot resources in hard, basement rock formations.
Geothermal Program Review XI: proceedings. Geothermal Energy - The Environmental Responsible Energy Technology for the Nineties

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1993-10-01

These proceedings contain papers pertaining to current research and development of geothermal energy in the USA. The seven sections of the document are: Overview, The Geysers, Exploration and Reservoir Characterization, Drilling, Energy Conversion, Advanced Systems, and Potpourri. The Overview presents current DOE energy policy and industry perspectives. Reservoir studies, injection, and seismic monitoring are reported for the geysers geothermal field. Aspects of geology, geochemistry and models of geothermal exploration are described. The Drilling section contains information on lost circulation, memory logging tools, and slim-hole drilling. Topics considered in energy conversion are efforts at NREL, condensation on turbines and geothermal materials.more » Advanced Systems include hot dry rock studies and Fenton Hill flow testing. The Potpourri section concludes the proceedings with reports on low-temperature resources, market analysis, brines, waste treatment biotechnology, and Bonneville Power Administration activities. Selected papers have been indexed separately for inclusion in the Energy Science and Technology Database.« less
Thermal history of Bakken shale in Williston basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gosnold, W.D. Jr.; Lefever, R.D.; Crashell, J.J.

1989-12-01

Stratigraphic and thermal conductivity data were combined to analyze the thermostratigraphy of the Williston basin. The present thermostratigraphy is characterized by geothermal gradients of the order of 60 mK/m in the Cenozoic and Mesozoic units, and 30 mK/m in the Paleozoic units. The differences in geothermal gradients are due to differences in thermal conductivities between the shale-dominated Mesozoic and Cenozoic units and the carbonate-dominated Paleozoic units. Subsidence and compaction rates were calculated for the basin and were used to determine models for time vs. depth and time vs. thermal conductivity relationships for the basin. The time/depth and time/conductivity relationships includemore » factors accounting for thermal conductivity changes due to compaction, cementation, and temperature. The thermal history of the Bakken shale, a primary oil source rock in the Williston basin, was determined using four different models, and values for Lopatin's time-temperature index (TTI) were calculated for each model. The first model uses a geothermal gradient calculated from bottom-hole temperature data, the second uses present-day thermostratigraphy, the third uses the thermostratigraphic relationship determined in this analysis, and the fourth modifies the third by including assumed variations in continental heat flow. The thermal histories and the calculated TTI values differ markedly among the models with TTI values differing by a factor of about two between some models.« less
Carbon dioxide diffuse emission and thermal energy release from hydrothermal systems at Copahue-Caviahue Volcanic Complex (Argentina)

NASA Astrophysics Data System (ADS)

Chiodini, Giovanni; Cardellini, Carlo; Lamberti, María Clara; Agusto, Mariano; Caselli, Alberto; Liccioli, Caterina; Tamburello, Giancarlo; Tassi, Franco; Vaselli, Orlando; Caliro, Stefano

2015-10-01

The north-western sector of Caviahue caldera (Argentina), close to the active volcanic system of Copahue, is characterized by the presence of several hydrothermal sites that host numerous fumarolic emissions, anomalous soil diffuse degassing of CO2 and hot soils. In March 2014, measurements of soil CO2 fluxes in 5 of these sites (namely, Las Máquinas, Las Maquinitas I, Las Maquinitas II, Anfiteatro, and Termas de Copahue) allowed an estimation that 165 t of deeply derived CO2 is daily released. The gas source is likely related to a relatively shallow geothermal reservoir containing a single vapor phase as also suggested by both the geochemical data from the 3 deep wells drilled in the 1980s and gas geoindicators applied to the fumarolic discharges. Gas equilibria within the H-C-O gas system indicate the presence of a large, probably unique, single phase vapor zone at 200-210 °C feeding the hydrothermal manifestations of Las Máquinas, Las Maquinitas I and II and Termas de Copahue. A natural thermal release of 107 MW was computed by using CO2 as a tracer of the original vapor phase. The magmatic signature of the incondensable fumarolic gases, the wide expanse of the hydrothermal areas and the remarkable high amount of gas and heat released by fluid expulsion seem to be compatible with an active magmatic intrusion beneath this portion of the Caviahue caldera.
Maps | Geospatial Data Science | NREL

Science.gov Websites

Maps Maps NREL develops an array of maps to support renewable energy development and generation resource in the United States by county Geothermal Maps of geothermal power plants, resources for enhanced geothermal systems, and hydrothermal sites in the United States Hydrogen Maps of hydrogen production
The helical screw expander evaluation project. [for geothermal wells

NASA Technical Reports Server (NTRS)

Mckay, R. A.

1977-01-01

A positive-displacement helical-screw expander of the Lysholm type has been adapted for geothermal service and successfully demonstrated in a 50 kW prototype power system. Evaluation of the expander by tests of a new model in a 1 MW power system under wellhead conditions in selected liquid-dominated geothermal fields is proposed. The objectives are to determine the performance characteristics of the expander and power system over a broad range of operating conditions and also to examine the concept of wellhead power plants. Throttling and fractionation of the fluids from the test wells is planned to simulate a wide range of wellhead pressures and steam fractions. Variation in the expander exhaust pressure is also planned. The investigation will include expander efficiency, corrosion, erosion, scale formation and control, and endurance testing. Interaction studies with the wells and an electric grid are also proposed.
COTHERM: Modelling fluid-rock interactions in Icelandic geothermal systems

NASA Astrophysics Data System (ADS)

Thien, Bruno; Kosakowski, Georg; Kulik, Dmitrii

2014-05-01

Mineralogical alteration of reservoir rocks, driven by fluid circulation in natural or enhanced geothermal systems, is likely to influence the long-term performance of geothermal power generation. A key factor is the change of porosity due to dissolution of primary minerals and precipitation of secondary phases. Porosity changes will affect fluid circulation and solute transport, which, in turn, influence mineralogical alteration. This study is part of the Sinergia COTHERM project (COmbined hydrological, geochemical and geophysical modeling of geotTHERMal systems) that is an integrative research project aimed at improving our understanding of the sub-surface processes in magmatically-driven natural geothermal systems. We model the mineralogical and porosity evolution of Icelandic geothermal systems with 1D and 2D reactive transport models. These geothermal systems are typically high enthalphy systems where a magmatic pluton is located at a few kilometers depth. The shallow plutons increase the geothermal gradient and trigger the circulation of hydrothermal waters with a steam cap forming at shallow depth. We investigate two contrasting geothermal systems: Krafla, for which the water recharge consists of meteoritic water; and Reykjanes, for which the water recharge mainly consists of seawater. The initial rock composition is a fresh basalt. We use the GEM-Selektor geochemical modeling package [1] for calculation of kinetically controlled mineral equilibria between the rock and the ingression water. We consider basalt minerals dissolution kinetics according to Palandri & Kharaka [2]. Reactive surface areas are assumed to be geometric surface areas, and are corrected using a spherical-particle surface/mass relationship. For secondary minerals, we consider the partial equilibrium assuming that the primary mineral dissolution is slow, and the secondary mineral precipitation is fast. Comparison of our modeling results with the mineralogical assemblages observed in the field by Gudmundsson & Arnorsson [3] and by Icelandic partners of the COTHERM project suggests that the concept of partial equilibrium with instantaneous precipitation of secondary minerals is not sufficient to satisfactorily describe the experimental data. Considering kinetic controls also for secondary minerals appears as indispensable to properly describe the geothermal system evolution using a reactive transport modelling approach [4]. [1] Kulik D.A., Wagner T., Dmytrieva S.V., Kosakowski G., Hingerl F.F., Chudnenko K.V., Berner U., 2013. GEM-Selektor geochemical modeling package: revised algorithm and GEMS3K numerical kernel for coupled simulation codes. Computational Geosciences 17, 1-24. http://gems.web.psi.ch. [2] Palandri, J.L., Kharaka, Y.K., 2004. A compilation of rate parameters of water-mineral interaction kinetics for application to geochemical modelling. U.S.Geological Survey, Menlo Park, CA, pp. 1-64. [3] Gudmundsson B.T., Arnorsson S., 2005. Secondary mineral-fluid equilibria in the Krafla and Namafjall geothermal systems, Iceland. Applied Geochememistry 20, 1607-1625. [4] Kosakowski, G., & Watanabe, N., 2013. OpenGeoSys-Gem: A numerical tool for calculating geochemical and porosity changes in saturated and partially saturated media. Physics and Chemistry of the Earth, Parts A/B/C. doi:10.1016/j.pce.2013.11.008
Integrated Geologic and Geophysical Approach for Establishing Geothermal Play Fairways and Discovering Blind Geothermal Systems in the Great Basin Region, Western USA: A Progress Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Faulds, James E.; Hinz, Nicholas H.; Coolbaugh, Mark F.

We have undertaken an integrated geologic, geochemical, and geophysical study of a broad 240-km-wide, 400-km-long transect stretching from west-central to eastern Nevada in the Great Basin region of the western USA. The main goal of this study is to produce a comprehensive geothermal potential map that incorporates up to 11 parameters and identifies geothermal play fairways that represent potential blind or hidden geothermal systems. Our new geothermal potential map incorporates: 1) heat flow; 2) geochemistry from springs and wells; 3) structural setting; 4) recency of faulting; 5) slip rates on Quaternary faults; 6) regional strain rate; 7) slip and dilationmore » tendency on Quaternary faults; 8) seismologic data; 9) gravity data; 10) magnetotelluric data (where available); and 11) seismic reflection data (primarily from the Carson Sink and Steptoe basins). The transect is respectively anchored on its western and eastern ends by regional 3D modeling of the Carson Sink and Steptoe basins, which will provide more detailed geothermal potential maps of these two promising areas. To date, geological, geochemical, and geophysical data sets have been assembled into an ArcGIS platform and combined into a preliminary predictive geothermal play fairway model using various statistical techniques. The fairway model consists of the following components, each of which are represented in grid-cell format in ArcGIS and combined using specified weights and mathematical operators: 1) structural component of permeability; 2) regional-scale component of permeability; 3) combined permeability, and 4) heat source model. The preliminary model demonstrates that the multiple data sets can be successfully combined into a comprehensive favorability map. An initial evaluation using known geothermal systems as benchmarks to test interpretations indicates that the preliminary modeling has done a good job assigning relative ranks of geothermal potential. However, a major challenge is defining logical relative rankings of each parameter and how best to combine the multiple data sets into the geothermal potential/ permeability map. Ongoing feedback and data analysis are in use to revise the grouping and weighting of some parameters in order to develop a more robust, optimized, final model. The final product will incorporate more parameters into a geothermal potential map than any previous effort in the region and may serve as a prototype to develop comprehensive geothermal potential maps for other regions.« less
Outstanding issues for new geothermal resource assessments

USGS Publications Warehouse

Williams, C.F.; Reed, M.J.

2005-01-01

A critical question for the future energy policy of the United States is the extent to which geothermal resources can contribute to an ever-increasing demand for electricity. Electric power production from geothermal sources exceeds that from wind and solar combined, yet the installed capacity falls far short of the geothermal resource base characterized in past assessments, even though the estimated size of the resource in six assessments completed in the past 35 years varies by thousands of Megawatts-electrical (MWe). The U. S. Geological Survey (USGS) is working closely with the Department of Energy's (DOE) Geothermal Research Program and other geothermal organizations on a three-year effort to produce an updated assessment of available geothermal resources. The new assessment will introduce significant changes in the models for geothermal energy recovery factors, estimates of reservoir permeability, limits to temperatures and depths for electric power production, and include the potential impact of evolving Enhanced (or Engineered) Geothermal Systems (EGS) technology.
Sertac Akar | NREL

Science.gov Websites

Sertac Akar Photo of Sertac Akar Sertac Akar Energy Analyst - Geothermal Sertac.Akar@nrel.gov | 303 systems (GIS) and remote sensing (RS) Research Interests Techno-economic analysis of geothermal energy resource assessment (exploration & production) Desalination of brackish water using geothermal energy
Geothermal application feasibility study for the New Mexico State University campus. Technical report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gunaji, N.N.; Thode, E.F.; Chaturvedi, L.

1978-12-01

The following are covered: a geothermal prospect conceptual study for NMSU campus, geothermal resources on and near NMSU land, present campus heating and cooling system, conceptual design and preliminary cost estimates - alternative systems, economic analysis, and legal and environmental considerations. (MHR)
GEOTHERMAL ENVIRONMENTAL ASSESSMENT: BEHAVIOR OF SELECTED GEOTHERMAL BRINE CONTAMINANTS IN PLANTS AND SOILS

EPA Science Inventory

The behavior of selected elements found in the Roosevelt Hot Springs KGRA geothermal fluids was investigated in both plant and soil systems. The kinetics of these potential environmental containments were studied by using soil columns and selected cultivated and native plant spec...
Further Development and Application of GEOFRAC-FLOW to a Geothermal Reservoir

DOE Office of Scientific and Technical Information (OSTI.GOV)

Einstein, Herbert; Vecchiarelli, Alessandra

2014-05-01

GEOFRAC is a three-dimensional, geology-based, geometric-mechanical, hierarchical, stochastic model of natural rock fracture systems. The main characteristics of GEOFRAC are its use of statistical input representing fracture patterns in the field in form of the fracture intensity P32 (fracture area per volume) and the best estimate fracture size E(A). This information can be obtained from boreholes or scanlines on the surface, on the one hand, and from window sampling of fracture traces on the other hand. In the context of this project, “Recovery Act - Decision Aids for Geothermal Systems”, GEOFRAC was further developed into GEOFRAC-FLOW as has been reportedmore » in the reports, “Decision Aids for Geothermal Systems - Fracture Pattern Modelling” and “Decision Aids for Geothermal Systems - Fracture Flow Modeling”. GEOFRAC-FLOW allows one to determine preferred, interconnected fracture paths and the flow through them.« less
Systems and methods for multi-fluid geothermal energy systems

DOEpatents

Buscheck, Thomas A.

2017-09-19

A method for extracting geothermal energy from a geothermal reservoir formation. A production well is used to extract brine from the reservoir formation. At least one of nitrogen (N.sub.2) and carbon dioxide (CO.sub.2) may be used to form a supplemental working fluid which may be injected into a supplemental working fluid injection well. The supplemental working fluid may be used to augment a pressure of the reservoir formation, to thus drive a flow of the brine out from the reservoir formation.

Impact of enhanced geothermal systems on US energy supply in the twenty-first century.

PubMed

Tester, Jefferson W; Anderson, Brian J; Batchelor, Anthony S; Blackwell, David D; DiPippo, Ronald; Drake, Elisabeth M; Garnish, John; Livesay, Bill; Moore, Michal C; Nichols, Kenneth; Petty, Susan; Toksoz, M Nafi; Veatch, Ralph W; Baria, Roy; Augustine, Chad; Murphy, Enda; Negraru, Petru; Richards, Maria

2007-04-15

Recent national focus on the value of increasing US supplies of indigenous renewable energy underscores the need for re-evaluating all alternatives, particularly those that are large and well distributed nationally. A panel was assembled in September 2005 to evaluate the technical and economic feasibility of geothermal becoming a major supplier of primary energy for US base-load generation capacity by 2050. Primary energy produced from both conventional hydrothermal and enhanced (or engineered) geothermal systems (EGS) was considered on a national scale. This paper summarizes the work of the panel which appears in complete form in a 2006 MIT report, 'The future of geothermal energy' parts 1 and 2. In the analysis, a comprehensive national assessment of US geothermal resources, evaluation of drilling and reservoir technologies and economic modelling was carried out. The methodologies employed to estimate geologic heat flow for a range of geothermal resources were utilized to provide detailed quantitative projections of the EGS resource base for the USA. Thirty years of field testing worldwide was evaluated to identify the remaining technology needs with respect to drilling and completing wells, stimulating EGS reservoirs and converting geothermal heat to electricity in surface power and energy recovery systems. Economic modelling was used to develop long-term projections of EGS in the USA for supplying electricity and thermal energy. Sensitivities to capital costs for drilling, stimulation and power plant construction, and financial factors, learning curve estimates, and uncertainties and risks were considered.
Synopsis of Past Stimulation Methods in Enhanced (Engineered) Geothermal Systems, Boreholes, and Existing Hydrothermal Systems with Success Analysis and Recommendations for Future Projects

NASA Astrophysics Data System (ADS)

Broadhurst, T.; Mattson, E.

2017-12-01

Enhanced geothermal systems (EGS) are gaining in popularity as a technology that can be used to increase areas for geothermal resource procurement. One of the most important factors in the success of an EGS system is the success of the subsurface reservoir that is used for fluid flow and heat mining through advection. There are numerous challenges in stimulating a successful reservoir, including maintaining flow rates, minimizing leak off, preventing short-circuiting, and reducing the risk of microseismicity associated with subsurface activity. Understanding past examples of stimulation can be invaluable in addressing these challenges. This study provides an overview of stimulation methods that have been employed in EGS systems from 1974-2017. We include all geothermal reservoirs and demonstration projects that have experienced hydrofracturing, chemical stimulation, and induced thermal stress for a comprehensive list. We also examine different metrics and measures of success in geothermal reservoir stimulation to draw conclusions and provide recommendations for future projects. Multiple project characteristics are reported including geologic setting, stress conditions, reservoir temperature, injection specifics, resulting microseismicity, and overall project goals. Insight into optimal and unproductive stimulation methods is crucial to conserving mental capital, utilizing project funding, and ensuring EGS technology advances as efficiently as possible.
Optimization of Well Configuration for a Sedimentary Enhanced Geothermal Reservoir

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhou, Mengnan; Cho, JaeKyoung; Zerpa, Luis E.

The extraction of geothermal energy in the form of hot water from sedimentary rock formations could expand the current geothermal energy resources toward new regions. From previous work, we observed that sedimentary geothermal reservoirs with relatively low permeability would require the application of enhancement techniques (e.g., well hydraulic stimulation) to achieve commercial production/injection rates. In this paper we extend our previous work to develop a methodology to determine the optimum well configuration that maximizes the hydraulic performance of the geothermal system. The geothermal systems considered consist of one vertical well doublet system with hydraulic fractures, and three horizontal well configurationsmore » with open-hole completion, longitudinal fractures and transverse fractures, respectively. A commercial thermal reservoir simulation is used to evaluate the geothermal reservoir performance using as design parameters the well spacing and the length of the horizontal wells. The results obtained from the numerical simulations are used to build a response surface model based on the multiple linear regression method. The optimum configuration of the sedimentary geothermal systems is obtained from the analysis of the response surface model. The proposed methodology is applied to a case study based on a reservoir model of the Lyons sandstone formation, located in the Wattenberg field, Denver-Julesburg basin, Colorado.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)

Faulds, James

We conducted a comprehensive analysis of the structural controls of geothermal systems within the Great Basin and adjacent regions. Our main objectives were to: 1) Produce a catalogue of favorable structural environments and models for geothermal systems. 2) Improve site-specific targeting of geothermal resources through detailed studies of representative sites, which included innovative techniques of slip tendency analysis of faults and 3D modeling. 3) Compare and contrast the structural controls and models in different tectonic settings. 4) Synthesize data and develop methodologies for enhancement of exploration strategies for conventional and EGS systems, reduction in the risk of drilling non-productive wells,more » and selecting the best EGS sites.« less
Geothermal Geodatabase for Routt Hot Springs, Routt County, Colorado

DOE Data Explorer

Richard Zehner

2012-11-01

This geodatabase was built to cover several geothermal targets developed by Flint Geothermal in 2012 during a search for high-temperature systems that could be exploited for electric power development. Several of the thermal springs and wells in the Routt Hot Spring and Steamboat Springs areahave geochemistry and geothermometry values indicative of high-temperature systems. Datasets include: 1. Results of reconnaissance shallow (2 meter) temperature surveys 2. Air photo lineaments 3. Groundwater geochemistry 5. Georeferenced geologic map of Routt County 6. Various 1:24,000 scale topographic maps
Hot Dry Rock; Geothermal Energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

None

1990-01-01

The commercial utilization of geothermal energy forms the basis of the largest renewable energy industry in the world. More than 5000 Mw of electrical power are currently in production from approximately 210 plants and 10 000 Mw thermal are used in direct use processes. The majority of these systems are located in the well defined geothermal generally associated with crustal plate boundaries or hot spots. The essential requirements of high subsurface temperature with huge volumes of exploitable fluids, coupled to environmental and market factors, limit the choice of suitable sites significantly. The Hot Dry Rock (HDR) concept at any depthmore » originally offered a dream of unlimited expansion for the geothermal industry by relaxing the location constraints by drilling deep enough to reach adequate temperatures. Now, after 20 years intensive work by international teams and expenditures of more than $250 million, it is vital to review the position of HDR in relation to the established geothermal industry. The HDR resource is merely a body of rock at elevated temperatures with insufficient fluids in place to enable the heat to be extracted without the need for injection wells. All of the major field experiments in HDR have shown that the natural fracture systems form the heat transfer surfaces and that it is these fractures that must be for geothermal systems producing from naturally fractured formations provide a basis for directing the forthcoming but, equally, they require accepting significant location constraints on HDR for the time being. This paper presents a model HDR system designed for commercial operations in the UK and uses production data from hydrothermal systems in Japan and the USA to demonstrate the reservoir performance requirements for viable operations. It is shown that these characteristics are not likely to be achieved in host rocks without stimulation processes. However, the long term goal of artificial geothermal systems developed by systematic engineering procedures at depth may still be attained if high temperature sites with extensive fracturing are developed or exploited. [DJE -2005]« less
Geothermal direct-heat utilization assistance. Quarterly report, January - March 1997

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lienau, P.

1997-04-01

This report summarizes geothermal technical assistance, R&D and technology transfer activities of the Geo-Heat Center at Oregon Institute of Technology for the second quarter of FY-97. It describes 176 contacts with parties during this period related to technical assistance with geothermal direct heat projects. Areas dealt with include geothermal heat pumps, space heating, greenhouses, aquaculture, equipment, economics and resources. Research activities are summarized on well pumping in commercial groundwater heat pump systems. A memorandum of understanding between the GHC and EIA is described. Work accomplishments on the Guidebook are discussed. Outreach activities include the publication of a geothermal direct usemore » Bulletin, dissemination of information, geothermal library, technical papers and seminars, and progress monitor reports on geothermal resources and utilization.« less
Cooperative geochemical investigation of geothermal resources in the Imperial Valley and Yuma areas. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Coplen, T.B.

1973-10-01

Preliminary studies indicate that the Imperial Valley has a large geothermal potential. In order to delineate additional geothermal systems a chemical and isotopic investigation of samples from water wells, springs, and geothermal wells in the Imperial Valley and Yuma areas was conducted. Na, K, and Ca concentrations of nearly 200 well water, spring water, hot spring, and geothermal fluid samples from the Imperial Valley area were measured by atomic absorption spectrophotometry. Fournier and Truesdell's function was determined for each water sample. Suspected geothermal areas are identified. Hydrogen and oxygen isotope abundances were determined in order to determine and to identifymore » the source of the water in the Mesa geothermal system. (JGB)« less
A comparison of economic evaluation models as applied to geothermal energy technology

NASA Technical Reports Server (NTRS)

Ziman, G. M.; Rosenberg, L. S.

1983-01-01

Several cost estimation and financial cash flow models have been applied to a series of geothermal case studies. In order to draw conclusions about relative performance and applicability of these models to geothermal projects, the consistency of results was assessed. The model outputs of principal interest in this study were net present value, internal rate of return, or levelized breakeven price. The models used were VENVAL, a venture analysis model; the Geothermal Probabilistic Cost Model (GPC Model); the Alternative Power Systems Economic Analysis Model (APSEAM); the Geothermal Loan Guarantee Cash Flow Model (GCFM); and the GEOCOST and GEOCITY geothermal models. The case studies to which the models were applied include a geothermal reservoir at Heber, CA; a geothermal eletric power plant to be located at the Heber site; an alcohol fuels production facility to be built at Raft River, ID; and a direct-use, district heating system in Susanville, CA.
Re-examining Potential for Geothermal Energy in United States

NASA Astrophysics Data System (ADS)

Showstack, Randy

New technological initiatives, along with potential policy and economic incentives, could help to bring about a resurgence in geothermal energy development in the United States, said several experts at a 22 May forum in Washington, D.C. The forum was sponsored by the House and Senate Renewable Energy and Energy Efficiency Caucuses, the Sustainable Energy Coalition, and the Environmental and Energy Study Institute. Among these initiatives is an ambitious program of the U.S. Department of Energy to expand existing geothermal energy fields and potentially create new fields through ``enhanced geothermal systems.'' In addition, a program of the Bush administration encourages geothermal development on some public lands, and current legislation would provide tax credits and other incentives for geothermal development.
Origin and transport of chloride in superheated geothermal steam

USGS Publications Warehouse

Truesdell, A.H.; Haizlip, J.R.; Armannsson, H.; D'Amore, F.

1989-01-01

Hydrogen chloride (HCl) is a known component of some volcanic gases and volcanic-related hydrothermal systems. It has recently been discovered in superheated steam in exploited geothermal systems, usually as a result of HCl-induced corrosion of well casing and steam gathering systems. Evaluation of four geothermal systems (Tatun, Taiwan; Krafla, Iceland; Larderello, Italy and The Geysers, USA) which produce CI-bearing steam provides evidence for the presence of Cl as HCl and the natural reservoir conditions which can produce HCl-bearing steam. Theoretical calculations defining the physical and chemical conditions of the reservoir liquid which can produce HCl-bearing steam are presented. The main factors are pH, temperature and Cl concentration. Lower pH, higher temperature and higher chlorinity allow more HCl to be volatilized with steam. In order to reach the surface in steam, the HCl cannot contact liquid water in which it is more soluble, essentially limiting transport to superheated steam. Temperature, pH and Cl concentration of reservoir liquids in each of the geothermal systems evaluated combine differently to produce HCl-bearing steam. ?? 1989.
Feasibility and Supply Analysis of U.S. Geothermal District Heating and Cooling System

NASA Astrophysics Data System (ADS)

He, Xiaoning

Geothermal energy is a globally distributed sustainable energy with the advantages of a stable base load energy production with a high capacity factor and zero SOx, CO, and particulates emissions. It can provide a potential solution to the depletion of fossil fuels and air pollution problems. The geothermal district heating and cooling system is one of the most common applications of geothermal energy, and consists of geothermal wells to provide hot water from a fractured geothermal reservoir, a surface energy distribution system for hot water transmission, and heating/cooling facilities to provide water and space heating as well as air conditioning for residential and commercial buildings. To gain wider recognition for the geothermal district heating and cooling (GDHC) system, the potential to develop such a system was evaluated in the western United States, and in the state of West Virginia. The geothermal resources were categorized into identified hydrothermal resources, undiscovered hydrothermal resources, near hydrothermal enhanced geothermal system (EGS), and deep EGS. Reservoir characteristics of the first three categories were estimated individually, and their thermal potential calculated. A cost model for such a system was developed for technical performance and economic analysis at each geothermally active location. A supply curve for the system was then developed, establishing the quantity and the cost of potential geothermal energy which can be used for the GDHC system. A West Virginia University (WVU) case study was performed to compare the competiveness of a geothermal energy system to the current steam based system. An Aspen Plus model was created to simulate the year-round campus heating and cooling scenario. Five cases of varying water flow rates and temperatures were simulated to find the lowest levelized cost of heat (LCOH) for the WVU case study. The model was then used to derive a levelized cost of heat as a function of the population density at a constant geothermal gradient. By use of such functions in West Virginia at a census tract level, the most promising census tracts in WV for the development of geothermal district heating and cooling systems were mapped. This study is unique in that its purpose was to utilize supply analyses for the GDHC systems and determine an appropriate economic assessment of the viability and sustainability of the systems. It was found that the market energy demand, production temperature, and project lifetime have negative effects on the levelized cost, while the drilling cost, discount rate, and capital cost have positive effects on the levelized cost by sensitivity analysis. Moreover, increasing the energy demand is the most effective way to decrease the levelized cost. The derived levelized cost function shows that for EGS based systems, the population density has a strong negative effect on the LCOH at any geothermal gradient, while the gradient only has a negative effect on the LCOH at a low population density.
Modeling of heat extraction from variably fractured porous media in Enhanced Geothermal Systems

DOE PAGES

Hadgu, Teklu; Kalinina, Elena Arkadievna; Lowry, Thomas Stephen

2016-01-30

Modeling of heat extraction in Enhanced Geothermal Systems is presented. The study builds on recent studies on the use of directional wells to improve heat transfer between doublet injection and production wells. The current study focuses on the influence of fracture orientation on production temperature in deep low permeability geothermal systems, and the effects of directional drilling and separation distance between boreholes on heat extraction. The modeling results indicate that fracture orientation with respect to the well-pair plane has significant influence on reservoir thermal drawdown. As a result, the vertical well doublet is impacted significantly more than the horizontal wellmore » doublet« less
GEO2D - Two-Dimensional Computer Model of a Ground Source Heat Pump System

DOE Data Explorer

James Menart

2013-06-07

This file contains a zipped file that contains many files required to run GEO2D. GEO2D is a computer code for simulating ground source heat pump (GSHP) systems in two-dimensions. GEO2D performs a detailed finite difference simulation of the heat transfer occurring within the working fluid, the tube wall, the grout, and the ground. Both horizontal and vertical wells can be simulated with this program, but it should be noted that the vertical wall is modeled as a single tube. This program also models the heat pump in conjunction with the heat transfer occurring. GEO2D simulates the heat pump and ground loop as a system. Many results are produced by GEO2D as a function of time and position, such as heat transfer rates, temperatures and heat pump performance. On top of this information from an economic comparison between the geothermal system simulated and a comparable air heat pump systems or a comparable gas, oil or propane heating systems with a vapor compression air conditioner. The version of GEO2D in the attached file has been coupled to the DOE heating and cooling load software called ENERGYPLUS. This is a great convenience for the user because heating and cooling loads are an input to GEO2D. GEO2D is a user friendly program that uses a graphical user interface for inputs and outputs. These make entering data simple and they produce many plotted results that are easy to understand. In order to run GEO2D access to MATLAB is required. If this program is not available on your computer you can download the program MCRInstaller.exe, the 64 bit version, from the MATLAB website or from this geothermal depository. This is a free download which will enable you to run GEO2D..
Geothermal direct use in the United States update: 1990-1994

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lienau, P.J.; Lund, J.W.; Culver, G.G.

1995-02-01

Geothermal energy is estimated to currently supply approximately 13,885 TJ/yr (13,180 x 10{sup 9} BTU/yr) of heat energy through direct heat applications in the United States. Table 1 summarizes the U.S. geothermal direct heat uses. It should be noted that Table 1 does not contain enhanced oil recovery, which was included in the 1990 update report. In the oil fields of the upper midwest (Montana, North Dakota and Wyoming), thermal waters are not being injected at higher temperatures than the oil producing zones. This means that there is no benefit to reducing oil viscosity, which would have increased production rates;more » therefore, resulting in this use being deleted from direct uses in the table. In the 1990 report two geothermal district heating systems were listed as under construction, Mammoth Lakes and Bridgeport, these systems have not been built although exploratory wells have been drilled. They are not included in the current summary of direct uses. There have been no new geothermal district heating systems started; however, San Bernardino and Klamath Falls have expanded their systems. Annual energy use of direct heat applications reported for both the 1990 and 1994 updates are shown. All of the categories experienced some increase in use, however the largest growth has been in geothermal heat pumps. From 1985 to 1990 the highest growth rate in geothermal heat pumps occurred, then tapered off some from 1990 to 1994. In the other five categories there has been a steady growth with the largest occurring in space heating, greenhouses and industrial plants. Greenhouse development has been significant in New Mexico and Utah and a new onion and garlic dehydration plant was built in Nevada.« less
Koenraad Beckers | NREL

Science.gov Websites

postdoctoral researcher working on geothermal energy and CSP projects. His interests include heat and mass geothermal energy systems modeling, reservoir simulation, and economic analysis, as well as on the design and transfer, energy conversion and storage systems, reservoir modeling, and direct-use applications of thermal
Philip, South Dakota geothermal district heating systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lund, J.W.

1997-12-01

The geothermal heating project in Philip, South Dakota which uses the waste water from the Haakon School has now been in operation for 15 years. This project was one of the 23 cost shared by the U.S. DOE starting in 1978, of which 15 became operational. This article describes the geothermal heating system for eight buildings in downtown Philip.
Magmatic-like fluid source of the Chingshui geothermal field, NE Taiwan evidenced by carbonate clumped-isotope paleothermometry

NASA Astrophysics Data System (ADS)

Lu, Yi-Chia; Song, Sheng-Rong; Wang, Pei-Ling; Wu, Chung-Che; Mii, Horng-Sheng; MacDonald, John; Shen, Chuan-Chou; John, Cédric M.

2017-11-01

The Chingshui geothermal field, a moderate-temperature and water-dominated hydrothermal system, was the site of the first geothermal power plant in Taiwan. Many geological, geophysical and geochemical studies using more than 21 drilled wells have been performed since the 1960s. However, there are still controversies regarding the heat and fluid sources due to the tectonically complicated geological setting. To clarify the heat and fluid sources, we analyzed clumped isotopes with carbon and oxygen isotopic compositions of calcite scaling in geothermal wells and veins on outcrops and calculated the δ18O values of the source fluids. Two populations of δ18O values were calculated: -5.8 ± 0.8‰ VSMOW from scaling in the well and -1.0 ± 1.6‰ to 10.0 ± 1.3‰ VSMOW from outcropping calcite veins, indicative of meteoric and magmatic fluid sources, respectively. Meanwhile, two hydrothermal reservoirs at different depths have been identified by magnetotelluric (MT) imaging with micro-seismicity underneath this area. As a result, we propose a two-reservoir model: the shallow reservoir provides fluids from meteoric water for the scaling sampled from wells, whereas the deep reservoir provides magmatic fluids from deep marble decarbonization recorded in outcropping calcite veins.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Akar, Sertac; Turchi, Craig

Substantial drought and declines in potable groundwater in the United States over the last decade has increased the demand for fresh water. Desalination of saline water such as brackish surface or groundwater, seawater, brines co-produced from oil and gas operations, industrial wastewater, blow-down water from power plant cooling towers, and agriculture drainage water can reduce the volume of water that requires disposal while providing a source of high-quality fresh water for industrial or commercial use. Membrane distillation (MD) is a developing technology that uses low-temperature thermal energy for desalination. Geothermal heat can be an ideal thermal-energy source for MD desalinationmore » technology, with a target range of $1/m3 to $2/m3 for desalinated water depending on the cost of heat. Three different cases were analyzed to estimate levelized cost of heat (LCOH) for integration of MD desalination technology with low-grade geothermal heat: (1) residual heat from injection brine at a geothermal power plant, (2) heat from existing underutilized low-temperature wells, and (3) drilling new wells for low-temperature resources. The Central and Western United States have important low-temperature (<90 degrees C) geothermal resource potential with wide geographic distribution, but these resources are highly underutilized because they are inefficient for power production. According to the USGS, there are 1,075 identified low temperature hydrothermal systems, 55 low temperature sedimentary systems and 248 identified medium to high temperature geothermal systems in the United States. The estimated total beneficial heat potential from identified low temperature hydrothermal geothermal systems and residual beneficial heat from medium to high temperature systems is estimated as 36,300 MWth, which could theoretically produce 1.4 to 7 million m3/day of potable water, depending on desalination efficiency.« less
Quantitative Analysis of Existing Conditions and Production Strategies for the Baca Geothermal System, New Mexico

NASA Astrophysics Data System (ADS)

Faust, Charles R.; Mercer, James W.; Thomas, Stephen D.; Balleau, W. Pete

1984-05-01

The Baca geothermal reservoir and adjacent aquifers in the Jemez Mountains of New Mexico comprise an integrated hydrogeologic system. Analysis of the geothermal reservoir either under natural conditions or subject to proposed development should account for the mass (water) and energy (heat) balances of adjacent aquifers as well as the reservoir itself. A three-dimensional model based on finite difference approximations is applied to this integrated system. The model simulates heat transport associated with the flow of steam and water through an equivalent porous medium. The Baca geothermal reservoir is dominated by flow in fractures and distinct strata, but at the scale of application the equivalent porous media concept is appropriate. The geothermal reservoir and adjacent aquifers are simulated under both natural conditions and proposed production strategies. Simulation of natural conditions compares favorably with observed pressure, temperature, and thermal discharge data. The history matching simulations show that the results used for comparison are most sensitive to vertical permeability and the area of an assumed high-permeability zone connecting the reservoir to a deep hydrothermal source. Simulations using proposed production strategies and optimistic estimates of certain hydrologic parameters and reservoir extent indicate that a 50-MW power plant could be maintained for a period greater than 30 years. This production, however, will result in significant decreases in the total water discharge to the Jemez River.

Hydrothemal Alteration Mapping Using Feature-Oriented Principal Component Selection (fpcs) Method to Aster DATA:WIKKI and Mawulgo Thermal Springs, Yankari Park, Nigeria

NASA Astrophysics Data System (ADS)

Abubakar, A. J.; Hashim, M.; Pour, A. B.

2017-10-01

Geothermal systems are essentially associated with hydrothermal alteration mineral assemblages such as iron oxide/hydroxide, clay, sulfate, carbonate and silicate groups. Blind and fossilized geothermal systems are not characterized by obvious surface manifestations like hot springs, geysers and fumaroles, therefore, they could not be easily identifiable using conventional techniques. In this investigation, the applicability of Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) were evaluated in discriminating hydrothermal alteration minerals associated with geothermal systems as a proxy in identifying subtle Geothermal systems at Yankari Park in northeastern Nigeria. The area is characterized by a number of thermal springs such as Wikki and Mawulgo. Feature-oriented Principal Component selection (FPCS) was applied to ASTER data based on spectral characteristics of hydrothermal alteration minerals for a systematic and selective extraction of the information of interest. Application of FPCS analysis to bands 5, 6 and 8 and bands 1, 2, 3 and 4 datasets of ASTER was used for mapping clay and iron oxide/hydroxide minerals in the zones of Wikki and Mawulgo thermal springs in Yankari Park area. Field survey using GPS and laboratory analysis, including X-ray Diffractometer (XRD) and Analytical Spectral Devices (ASD) were carried out to verify the image processing results. The results indicate that ASTER dataset reliably and complementarily be used for reconnaissance stage of targeting subtle alteration mineral assemblages associated with geothermal systems.
The role of thermal vapor diffusion in the subsurface hydrologic evolution of Mars

NASA Technical Reports Server (NTRS)

Clifford, Stephen M.

1991-01-01

The hydrologic response of groundwater to the thermal evolution of the early martian crust is considered. When a temperature gradient is present in a moist porous medium, it gives rise to a vapor-pressure gradient that drives the diffusion of water vapor from regions of high to low temperature. By this process, a geothermal gradient as small as 15 K/km could drive the vertical transport of 1 km of water to the freezing front at the base of the martian crysophere every 10 exp 6-10 exp 7 years, or the equivalent of about 100-1000 km of water over the course of martian geologic history. Models of the thermal history of Mars suggest that this thermally-driven vapor flux may have been as much as 3-5 times greater in the past. The magnitude of this transport suggests that the process of geothermally-induced vapor diffusion may have played a critical role in the initial emplacement of ground ice and the subsequent geomorphic and geochemical evolution of the martian crust.
Atmospheric Calibration for Cassini Radio Science

NASA Technical Reports Server (NTRS)

Resch, G. M.; Bar-Sever, Y.; Keihm, S.; Kroger, P.; Linfield, R.; Mahoney, M. J.; Tanner, A.; Teitelbaum, L.

1996-01-01

The signals from the Cassini spacecraft that will be affected by delay fluctuations in the Earth's atmosphere. These fluctuations are dominated by water vapor in the troposphere, and in the case of Gravitaional Wave Experiment (GWE), they are likely to be a limiting error source. A passive remote sensing system, centered around a water vapor radiometer (WVR), has been developed to provide calibrations of water vapor fluctuations during radio science experiments.
GeoVision Study | Geothermal Technologies | NREL

Science.gov Websites

and technical issues of advanced technologies and potential future impacts and calculating geothermal : Exploration Reservoir development and management Social and environmental impacts Hybrid systems Thermal
World Geothermal Congress WGC-2015

NASA Astrophysics Data System (ADS)

Tomarov, G. V.; Shipkov, A. A.

2016-08-01

This article discusses materials and results of the World Geothermal Congress that was held in Melbourne (Australia) from April 19 to April 25, 2015. Information on the extent and technological features of utilization of geothermal resources for heat supply and power production, as well as in other economic areas, is given. A stable growth in the capacity and number of geothermal power systems that is determined by ecological cleanliness, economic efficiency, and the highest (among renewable energy sources) indicators of installed capacity utilization is shown. It was noted that combined schemes of geothermal power plants (GPPs), such as turbine units of different type (binary units, units with one or two separation pressures, etc.), have become more frequently used to increase the efficiency of utilization of geothermal heat carrier. Actual data determining room heating systems with the total worldwide capacity of nearly 50000 MW thermal (MWt) as the most currently significant segment of consumption of geothermal waters are given. In addition, geothermal resources are also utilized in soil pumps, balneological and sports basins, greenhouse complexes, and other manufactures. It was noted that geological studies were carried out in more than 40 countries, with the development of methods of simulation of tanks for the existing and new geothermal fields. Trends of development and the role of geothermal power engineering in the energy supply of many countries are shown. It was shown that prospects for the development of geothermal power generation are significantly associated with utilization of low-temperature geothermal sources in binary power generating units, as well as with the increase in installed capacity of operating geothermal power plants (GPPs) without drilling additional wells, i.e., by using waste geothermal heat carrier in binary-cycle or combined-cycle power plants. The article provides data on a pilot binary power unit at Pauzhetka GPP and on a promising Russian geothermal project to increase the installed capacity of Mutnovsk GPP (whose current capacity is 50.0 (2 × 25.0) MW of electric power) by 25% by constructing a combined binary-cycle power generating unit on the basis of waste separate utilization.
Noble gas isotopes as low-budget exploration and monitoring tool for high- and low-temperature geothermal systems in extensional tectonic regimes

NASA Astrophysics Data System (ADS)

Kraml, Michael; Jodocy, Marco; Aeschbach, Werner; Kreuter, Horst

2017-04-01

Since viable geothermal systems in extensional settings are sparse compared to those situated in subduction zone environments, a specifically adapted exploration methodology of the former is currently not fully established. Standardized exploration methods applicable to geothermal systems related to subduction zones do not always deliver reliable or even deliver misleading results (e.g. Ochmann et al. 2010). The identification of promising prospects at the beginning of surface exploration studies is saving time and money of the project developer and investor. Noble gas isotope analyses can provide a low-budget tool for assessing the quality of the prospect in a very early exploration phase. Case studies of high- and low-temperature prospects situated in the East African Rift System and the Upper Rhine Graben, Germany will be presented and compared to other extensional areas like the Basin and Range Province, U.S.A. (Kraml et al. 2016a,b). Noble gas isotopes are also a versatile tool for monitoring of geothermal reservoirs during the production/exploitation phase. References Kraml, M., Jodocy, M., Reinecker, J., Leible, D., Freundt, F., Al Najem, S., Schmidt, G., Aeschbach, W., and Isenbeck-Schroeter, M. (2016a): TRACE: Detection of Permeable Deep-Reaching Fault Zone Sections in the Upper Rhine Graben, Germany, During Low-Budget Isotope-Geochemical Surface Exploration. Proceedings European Geothermal Congress 2016, Strasbourg, France, 19-24 Sept 2016 Kraml, M., Kaudse, T., Aeschbach, W. and Tanzanian Exploration Team (2016b): The search for volcanic heat sources in Tanzania: A helium isotope perspective. Proceedings 6th African Rift Geothermal Conference, Addis Ababa, Ethiopia, 2nd-4th November 2016 Ochmann, N., Kraml, M., Lindenfeld, M., Yakovlev, A., Rümpker, G., Babirye, P. (2010): Microearthquake Survey at the Buranga Geothermal Prospect (Western Uganda). Proceedings World Geothermal Congress, 25-29 April 2010, Bali, Indonesia (paper number 1126)
Transported Low-Temperature Geothermal Energy for Thermal End Uses Final Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang, Zhiyao; Liu, Xiaobing; Gluesenkamp, Kyle R

2016-10-01

The use of geothermal energy is an emerging area for improving the nation’s energy resiliency. Conventionally, geothermal energy applications have focused on power generation using high temperature hydrothermal resources or enhanced geothermal systems. However, many low temperature (below 150°C/300°F) geothermal resources are also available but have not been fully utilized. For example, it is estimated that 25 billion barrels of geothermal fluid (mostly water and some dissolved solids) at 176°F to 302°F (80°C to 150°C) is coproduced annually at oil and gas wells in the United States (DOE 2015). The heat contained in coproduced geothermal fluid (also referred as “coproducedmore » water”) is typically wasted because the fluid is reinjected back into the ground without extracting the heat.« less
Analysis geothermal prospect of Mt. Endut using geochemistry methods

NASA Astrophysics Data System (ADS)

Sobirin, R.; Permadi, A. N.; Akbar, A. M.; Wildan, D.; Supriyanto

2017-07-01

Mt. Endut geothermal area is located in Lebak district, Banten province, about 40 km to the south of the town of Rangkasbitung. There are four manifestations of hot springs i.e: Handeuleum hot springs, Cikawah 1, Cikawah 2, and Gajrug. Based on geochemical analysis using Na-K-Mg triangular diagrams, Cl-Li-B, and Cl-SO4-HCO3, it is known that Cikawah 1 hot springs is chloride type and the other springs are bicarbonate type. Reservoir temperature range is from 162°C to 180°C are predicted by SiO2 and NaK geothermometers. In general all hot springs are out flows, but there is an hypothesis that Cikawah 1 is the up flow. Because it is in partial equilibrium and chloride type. Mount Endut has a hydrothermal system with a fluid reservoir in the form of hot water or water dominated system. The geothermal prospect area of Mount Endut is located around the Cikawah manifestation to the western part of the Endut mountain. Further research is required by conducting geophysical surveys around the Mount Endut.
The Role of Heat in the Development of Energy and Mineral Resources in the Northern Basin and Range Province

NASA Astrophysics Data System (ADS)

Armstrong, Richard L.

It is now just over a decade since OPEC escalated the price of oil and triggered a flurry of alternate energy research and changing energy consumption practices. One scientific impact of that historical economic turning point was the launching of geothermal exploration programs of unprecedented intensity that focused on Cenozoic volcanic rocks and active, as well as fossil, geothermal systems. The good science that was already being done on such rocks and systems was both accelerated and diluted by government-funded research and energy industry exploration efforts. After the initial flood of detailed reports, gray literature, and documents interred in company files, we are observing the appearance of syntheses of just what happened and what progress was achieved during the geothermal boom (which has now wilted to the quiet development of a few most promising sites). Recent examples of geothermal synthesis literature include the book Geothermal Systems by L. Rybach and L.J. Muffler (John Wiley, New York, 1981), publications like Oregon Department of Geology and Mineral Industries Paper 15 by G.R. Priest et al. (1983) entitled “Geology and geothermal resources of central Oregon Cascade range,” and informative maps like the U.S. Geological Survey series summarizing late Cenozoic volcanic rock distribution and age (R.G. Luedke and R.L. Smith, maps 1-1091 A to D, 1979 to 1982), and state and regional geothermal resources maps (NOAA National Geophysical Data Center, 1977-1982). The book under review here is part of this second literature wave, a useful primary reference, collection of syntheses, and literature guide but certainly not unique.
The Geysers-Clear Lake geothermal area, California - an updated geophysical perspective of heat sources

USGS Publications Warehouse

Stanley, W.D.; Blakely, R.J.

1995-01-01

The Geysers-Clear Lake geothermal area encompasses a large dry-steam production area in The Geysers field and a documented high-temperature, high-pressure, water-dominated system in the area largely south of Clear Lake, which has not been developed. An updated view is presented of the geological/geophysical complexities of the crust in this region in order to address key unanswered questions about the heat source and tectonics. Forward modeling, multidimensional inversions, and ideal body analysis of the gravity data, new electromagnetic sounding models, and arguments made from other geophysical data sets suggest that many of the geophysical anomalies have significant contributions from rock property and physical state variations in the upper 7 km and not from "magma' at greater depths. Regional tectonic and magmatic processes are analyzed to develop an updated scenario for pluton emplacement that differs substantially from earlier interpretations. In addition, a rationale is outlined for future exploration for geothermal resources in The Geysers-Clear Lake area. -from Authors
Geothermal Water Use: Life Cycle Water Consumption, Water Resource Assessment, and Water Policy Framework

DOE Data Explorer

Schroeder, Jenna N.

2014-06-10

This report examines life cycle water consumption for various geothermal technologies to better understand factors that affect water consumption across the life cycle (e.g., power plant cooling, belowground fluid losses) and to assess the potential water challenges that future geothermal power generation projects may face. Previous reports in this series quantified the life cycle freshwater requirements of geothermal power-generating systems, explored operational and environmental concerns related to the geochemical composition of geothermal fluids, and assessed future water demand by geothermal power plants according to growth projections for the industry. This report seeks to extend those analyses by including EGS flash, both as part of the life cycle analysis and water resource assessment. A regional water resource assessment based upon the life cycle results is also presented. Finally, the legal framework of water with respect to geothermal resources in the states with active geothermal development is also analyzed.
Chemical Signatures of and Precursors to Fractures Using Fluid Inclusion Stratigraphy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lorie M. Dilley

Enhanced Geothermal Systems (EGS) are designed to recover heat from the subsurface by mechanically creating fractures in subsurface rocks. Open or recently closed fractures would be more susceptible to enhancing the permeability of the system. Identifying dense fracture areas as well as large open fractures from small fracture systems will assist in fracture stimulation site selection. Geothermal systems are constantly generating fractures (Moore, Morrow et al. 1987), and fluids and gases passing through rocks in these systems leave small fluid and gas samples trapped in healed microfractures. These fluid inclusions are faithful records of pore fluid chemistry. Fluid inclusions trappedmore » in minerals as the fractures heal are characteristic of the fluids that formed them, and this signature can be seen in fluid inclusion gas analysis. This report presents the results of the project to determine fracture locations by the chemical signatures from gas analysis of fluid inclusions. With this project we hope to test our assumptions that gas chemistry can distinguish if the fractures are open and bearing production fluids or represent prior active fractures and whether there are chemical signs of open fracture systems in the wall rock above the fracture. Fluid Inclusion Stratigraphy (FIS) is a method developed for the geothermal industry which applies the mass quantification of fluid inclusion gas data from drill cuttings and applying known gas ratios and compositions to determine depth profiles of fluid barriers in a modern geothermal system (Dilley, 2009; Dilley et al., 2005; Norman et al., 2005). Identifying key gas signatures associated with fractures for isolating geothermal fluid production is the latest advancement in the application of FIS to geothermal systems (Dilley and Norman, 2005; Dilley and Norman, 2007). Our hypothesis is that peaks in FIS data are related to location of fractures. Previous work (DOE Grant DE-FG36-06GO16057) has indicated differences in the chemical signature of fluid inclusions between open and closed fractures as well as differences in the chemical signature of open fractures between geothermal systems. Our hypothesis is that open fracture systems can be identified by their FIS chemical signature; that there are differences based on the mineral assemblages and geology of the system; and that there are chemical precursors in the wall rock above open, large fractures. Specific goals for this project are: (1) To build on the preliminary results which indicate that there are differences in the FIS signatures between open and closed fractures by identifying which chemical species indicate open fractures in both active geothermal systems and in hot, dry rock; (2) To evaluate the FIS signatures based on the geology of the fields; (3) To evaluate the FIS signatures based on the mineral assemblages in the fracture; and (4) To determine if there are specific chemical signatures in the wall rock above open, large fractures. This method promises to lower the cost of geothermal energy production in several ways. Knowledge of productive fractures in the boreholes will allow engineers to optimize well production. This information can aid in well testing decisions, well completion strategies, and in resource calculations. It will assist in determining the areas for future fracture enhancement. This will develop into one of the techniques in the 'tool bag' for creating and managing Enhanced Geothermal Systems.« less
The activity-composition relationship of oxygen and hydrogen isotopes in aqueous salt solutions: III. Vapor-liquid water equilibration of NaCl solutions to 350°C

NASA Astrophysics Data System (ADS)

Horita, Juske; Cole, David R.; Wesolowski, David J.

1995-03-01

The effect of dissolved NaCl on equilibrium oxygen and hydrogen isotope fractionation factors between liquid water and water vapor was precisely determined in the temperature range from 130-350°C, using two different types of apparatus with static or dynamic sampling techniques of the vapor phase. The magnitude of the oxygen and hydrogen isotope effects of NaCl is proportional to the molality of liquid NaCl solutions at a given temperature. Dissolved NaCl lowers appreciably the hydrogen isotope fractionation factor between liquid water and water vapor over the entire temperature range. NaCl has little effect on the oxygen isotope fractionation factor at temperatures below about 200°C, with the magnitude of the salt effect gradually increasing from 200-350°C. Our results are at notable variance with those of Truesdell (1974) and Kazahaya (1986), who reported large oxygen and hydrogen isotope effects of NaCl with very complex dependencies on temperature and NaCl molality. Our high-temperature results have been regressed along with our previous results between 50 and 100°C (Horita et al., 1993a) and the low-temperature literature data to simple equations which are valid for NaCl solutions from 0 to at least 5 molal NaCl in the temperature range from 10-350°C. Our preliminary results of oxygen isotope fractionation in the system CaCO3-water ± NaCl at 300°C and 1 kbar are consistent with those obtained from the liquid-vapor equilibration experiments, suggesting that the isotope salt effects are common to systems involving brines and any other coexisting phases or species (gases, minerals, dissolved species, etc.). The observed NaCl isotope effects at elevated temperatures should be taken into account in the interpretation of isotopic data of brine-dominated natural systems.
Flooded Underground Coal Mines: A Significant Source of Inexpensive Geothermal Energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Watzlaf, G.R.; Ackman, T.E.

2007-04-01

Many mining regions in the United States contain extensive areas of flooded underground mines. The water within these mines represents a significant and widespread opportunity for extracting low-grade, geothermal energy. Based on current energy prices, geothermal heat pump systems using mine water could reduce the annual costs for heating to over 70 percent compared to conventional heating methods (natural gas or heating oil). These same systems could reduce annual cooling costs by up to 50 percent over standard air conditioning in many areas of the country. (Formatted full-text version is released by permission of publisher)
Value of Information Evaluation using Field Data

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trainor-Guitton, W.

2015-06-15

Value of information (VOI) provides the ability to identify and prioritize useful information gathering for a geothermal prospect, either hydrothermal or for enhanced geothermal systems. Useful information provides a value greater than the cost of the information; wasteful information costs more than the expected value of the information. In this project we applied and refined VOI methodologies on selected geothermal prospects.
Production induced boiling and cold water entry in the Cerro Prieto geothermal reservoir indicated by chemical and physical measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Grant, M.A.; Truesdell, A.H.; Manon, A.

1981-01-01

Chemical and physical data suggest that the relatively shallow western part of the Cerro Prieto reservoir is bounded below by low permeability rocks, and above and at the sides by an interface with cooler water. There is no continuous permeability barrier around or immediately above the reservoir. Permeability within the reservoir is dominantly intergranular. Mixture with cooler water rather than boiling is the dominant cooling process in the natural state, and production causes displacement of hot water by cooler water, not by vapor. Local boiling occurs near most wells in response to pressure decreases, but no general vapor zone hasmore » formed.« less
Exploration criteria for low permeability geothermal resources. Final report. [Coso KGRA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Norton, D.

1977-10-01

Low permeability geothermal systems related to high temperature plutons in the upper crust were analyzed in order to ascertain those characteristics of these systems which could be detected by surface and shallow subsurface exploration methods. Analyses were designed to integrate data and concepts from the literature, which relate to the transport processes, together with computer simulation of idealized systems. The systems were analyzed by systematically varying input parameters in order to understand their effect on the variables which might be measured in an exploration-assessment program. The methods were applied to a prospective system in its early stages of evaluation. Datamore » from the Coso system were used. The study represents a first-order approximation to transport processes in geothermal systems, which consist of high temperature intrusions, host rock, and fluids. Included in an appendix are operations procedures for interactive graphics programs developed during the study. (MHR)« less
Performance of deep geothermal energy systems

NASA Astrophysics Data System (ADS)

Manikonda, Nikhil

Geothermal energy is an important source of clean and renewable energy. This project deals with the study of deep geothermal power plants for the generation of electricity. The design involves the extraction of heat from the Earth and its conversion into electricity. This is performed by allowing fluid deep into the Earth where it gets heated due to the surrounding rock. The fluid gets vaporized and returns to the surface in a heat pipe. Finally, the energy of the fluid is converted into electricity using turbine or organic rankine cycle (ORC). The main feature of the system is the employment of side channels to increase the amount of thermal energy extracted. A finite difference computer model is developed to solve the heat transport equation. The numerical model was employed to evaluate the performance of the design. The major goal was to optimize the output power as a function of parameters such as thermal diffusivity of the rock, depth of the main well, number and length of lateral channels. The sustainable lifetime of the system for a target output power of 2 MW has been calculated for deep geothermal systems with drilling depths of 8000 and 10000 meters, and a financial analysis has been performed to evaluate the economic feasibility of the system for a practical range of geothermal parameters. Results show promising an outlook for deep geothermal systems for practical applications.
Shallow Geothermal Admissibility Maps: a Methodology to Achieve a Sustainable Development of Shallow Geothermal Energy with Regards to Groundwater Resources

NASA Astrophysics Data System (ADS)

Bréthaut, D.; Parriaux, A.; Tacher, L.

2009-04-01

Implantation and use of shallow geothermal systems may have environmental impacts. Traditionally, risks are divided into 2 categories: direct and indirect. Direct risks are linked with the leakage of the circulating fluid (usually water with anti-freeze) of ground source heat pumps into the underground which may be a source of contamination. Indirect risks are linked with the borehole itself and the operation of the systems which can modify the groundwater flow, change groundwater temperature and chemistry, create bypasses from the surfaces to the aquifers or between two aquifers. Groundwater source heat pumps (GWSHP) may provoke indirect risks, while ground source heat pumps (GSHP) may provoke both direct and indirect risks. To minimize those environmental risks, the implantation of shallow geothermal systems must be regulated. In 2007, more than 7000 GSHP have been installed in Switzerland, which represents 1.5 Mio drilled meters. In the canton of Vaud, each shallow geothermal project has to be approved by the Department of the Environment. Approximately 1500 demands have been treated during 2007, about 15 times more than in 1990. Mapping shallow geothermal systems implantation restrictions due to environmental constrains permits: 1) to optimize the management and planning of the systems, 2) to minimize their impact on groundwater resources and 3) to facilitate administrative procedures for treating implantation demands. Such maps are called admissibility maps. Here, a methodology to elaborate them is presented and tested. Interactions between shallow geothermal energy and groundwater resources have been investigated. Admissibility criteria are proposed and structured into a flow chart which provides a decision making tool for shallow geothermal systems implantation. This approach has been applied to three areas of West Switzerland ranging from 2 to 6 km2. For each area, a geological investigation has been realized and complementary territorial information (e.g. map of contaminated areas) was gathered in order to produce the admissibility maps. For one area, a more detailed study has been performed and a complete 3D geological model has been constructed using an in-house modelling software called GeoShape. The model was then imported into a geographical information system which has been used to realize the admissibility map. Resulting maps were judged to be consistent and satisfying. In a second part of the project, this method will be applied at a larger scale. An admissibility map of the canton of Vaud (3200 km2) will be created. Considering the fast growth of the number of implanted GSHP and GWSHP throughout the world, it is clear that admissibility maps will play a major role in developing shallow geothermal energy as an environmentally friendly and sustainable resource.
Fluid inclusion from drill hole DW-5, Hohi geothermal area, Japan: Evidence of boiling and procedure for estimating CO2 content

USGS Publications Warehouse

Sasada, M.; Roedder, E.; Belkin, H.E.

1986-01-01

Fluid inclusion studies have been used to derive a model for fluid evolution in the Hohi geothermal area, Japan. Six types of fluid inclusions are found in quartz obtained from the drill core of DW-5 hole. They are: (I) primary liquid-rich with evidence of boiling; (II) primary liquid-rich without evidence of boiling; (III) primary vapor-rich (assumed to have been formed by boiling); (IV) secondary liquid-rich with evidence of boiling; (V) secondary liquid-rich without evidence of boiling; (VI) secondary vapor-rich (assumed to have been formed by boiling). Homogenization temperatures (Th) range between 196 and 347??C and the final melting point of ice (Tm) between -0.2 and -4.3??C. The CO2 content was estimated semiquantitatively to be between 0 and 0.39 wt. % based on the bubble behavior on crushing. NaCl equivalent solid solute salinity of fluid inclusions was determined as being between 0 and 6.8 wt. % after minor correction for CO2 content. Fluid inclusions in quartz provide a record of geothermal activity of early boiling and later cooling. The CO2 contents and homogenization temperatures of fluid inclusions with evidence of boiling generally increase with depth; these changes, and NaCl equivalent solid solute salinity of the fluid can be explained by an adiabatic boiling model for a CO2-bearing low-salinity fluid. Some high-salinity inclusions without CO2 are presumed to have formed by a local boiling process due to a temperature increase or a pressure decrease. The liquid-rich primary and secondary inclusions without evidence of boiling formed during the cooling process. The salinity and CO2 content of these inclusions are lower than those in the boiling fluid at the early stage, probably as a result of admixture with groundwater. ?? 1986.

Geothermal Systems for School.

ERIC Educational Resources Information Center

Dinse, David H.

1998-01-01

Describes an award-winning school heating and cooling system in which two energy-efficient technologies, variable-flow pumping and geothermal heat pumps, were combined. The basic system schematic and annual energy use and cost savings statistics are provided. (GR)
Preliminary study of Songa-Wayaua geothermal prospect area using volcanostratigraphy and remote sensing analysis

NASA Astrophysics Data System (ADS)

Asokawaty, Ribka; Nugroho, Indra; Satriana, Joshua; Hafidz, Muhamad; Suryantini

2017-12-01

Songa-Wayaua geothermal prospect area is located on Bacan Island, Northern Molluca Province. Geothermal systems in this area associated with three Quartenary volcanoes, such as Mt. Pele-pele, Mt. Lansa, and Mt. Bibinoi. Based on literature study, five surface manifestations such as hot springs and alteration occurred within this area. The active manifestations indicate that Songa-Wayaua area has potential geothermal resource. This study objective is to evaluate Songa-Wayaua geothermal system on preliminary study stage by using volcanostratigraphy and remote sensing analysis to delineate the boundary of geothermal system area. The result of this study showed that Songa-Wayaua prospect area has four heat sources potential (e.g. Pele-pele Hummock, Lansa Hummock, Songa Hummock, and Bibinoi Hummock), controlled by geological structure presented by Pele-pele Normal Fault, and had three places as the recharge and discharge area which are very fulfilling as a geothermal system.
Molecular carbon isotopic evidence for the origin of geothermal hydrocarbons

USGS Publications Warehouse

Des Marais, D.J.; Donchin, J.H.; Nehring, N.L.; Truesdell, A.H.

1981-01-01

Previous interest in light hydrocarbons from geothermal systems has focused principally on the origin of the methane1 and the estimation of subsurface temperatures from the carbon isotopic content of coexisting methane and carbon dioxide1-3. Higher molecular weight hydrocarbons were first reported in gases from Yellowstone National Park4, and have since been found to occur commonly in geothermal emanations in the western United States5. Isotopic measurements of individual geothermal hydrocarbons are now reported which help to explain the origin of these hydrocarbons. The thermal decomposition of sedimentary or groundwater organic matter is a principal source of hydrocarbons in four geothermal areas in western North America. ?? 1981 Nature Publishing Group.
Analytical estimation show low depth-independent water loss due to vapor flux from deep aquifers

NASA Astrophysics Data System (ADS)

Selker, John S.

2017-06-01

Recent articles have provided estimates of evaporative flux from water tables in deserts that span 5 orders of magnitude. In this paper, we present an analytical calculation that indicates aquifer vapor flux to be limited to 0.01 mm/yr for sites where there is negligible recharge and the water table is well over 20 m below the surface. This value arises from the geothermal gradient, and therefore, is nearly independent of the actual depth of the aquifer. The value is in agreement with several numerical studies, but is 500 times lower than recently reported experimental values, and 100 times larger than an earlier analytical estimate.
Industrially induced changes in Earth structure at the geysers geothermal area, California

USGS Publications Warehouse

Foulger, G.R.; Grant, C.C.; Ross, A.; Julian, B.R.

1997-01-01

Industrial exploitation is causing clearly-measurable changes in Earth structure at The Geysers geothermal area, California. Production at The Geysers peaked in the late 1980s at ???3.5 ?? 103 kg s-1 of steam and 1800 MW of electricity. It subsequently decreased by about 10% per year [Barker et al., 1992] because of declining reservoir pressure. The steam reservoir coincides with a strong negative anomaly (???0.16, ???9%) in the compressional-to-shear seismic wave speed ratio vP/vS, consistent with the expected effects of low-pressure vapor-phase pore fluid [Julian et al., 1996]. Between 1991 and 1994 this anomaly increased in amplitude by up to about 0.07 (???4%). This is consistent with the expected effects of continued pressure reduction and conversion of pore water to steam as a result of exploitation. These unique results show that vP/vS tomography can easily detect saturation changes caused by exploitation of reservoirs, and is a potentially valuable technique for monitoring environmental change. They also provide geophysical observational evidence that geothermal energy is not a renewable energy source.
Industrially induced changes in Earth structure at the Geysers Geothermal Area, California

NASA Astrophysics Data System (ADS)

Foulger, G. R.; Grant, C. C.; Ross, A.; Julian, B. R.

Industrial exploitation is causing clearly-measurable changes in Earth structure at The Geysers geothermal area, California. Production at The Geysers peaked in the late 1980s at ˜3.5 × 10³ kg s-1 of steam and 1800 MW of electricity. It subsequently decreased by about 10% per year [Barker et al., 1992] because of declining reservoir pressure. The steam reservoir coincides with a strong negative anomaly (˜0.16, ˜9%) in the compressional-to-shear seismic wave speed ratio VP/ VS, consistent with the expected effects of low-pressure vapor-phase pore fluid [Julian et al., 1996]. Between 1991 and 1994 this anomaly increased in amplitude by up to about 0.07 (˜4%). This is consistent with the expected effects of continued pressure reduction and conversion of pore water to steam as a result of exploitation. These unique results show that VP/VS tomography can easily detect saturation changes caused by exploitation of reservoirs, and is a potentially valuable technique for monitoring environmental change. They also provide geophysical observational evidence that geothermal energy is not a renewable energy source.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Kubik, Michelle

A comprehensive assessment of enhanced, or engineered, geothermal systems was carried out by an 18-member panel assembled by the Massachusetts Institute of Technology (MIT) to evaluate the potential of geothermal energy becoming a major energy source for the United States.
Estimation of the sustainable geothermal potential of Vienna

NASA Astrophysics Data System (ADS)

Tissen, Carolin; Benz, Susanne A.; Keck, Christiane A.; Bayer, Peter; Blum, Philipp

2017-04-01

Regarding the limited availability of fossil fuels and the absolute necessity to reduce CO2 emissions in order to mitigate the worldwide climate change, renewable resources and new energy systems are required to provide sustainable energy for the future. Shallow geothermal energy holds a huge untapped potential especially for heating and hot water, which represent up to 50% of the global energy demand. Previous studies quantified the capacity of shallow geothermal energy for closed and open systems in cities such as Vienna, London (Westminster) and Ludwigsburg in Germany. In the present study, these approaches are combined and also include the anthropogenic heat input by the urban heat island (UHI) effect. The objective of the present study is therefore to estimate the sustainable geothermal potential of Vienna. Furthermore, the amount of energy demand for heating and hot water that can be supplied by open and closed geothermal systems will be determined. The UHI effect in Vienna is reflected in higher ground water temperatures within the city centre (14 ˚ C to 18 ˚ C) in comparison to lower ones in rural areas (10 ˚ C to 13 ˚ C). A preliminary estimation of the anthropogenic heat flow into the ground water caused by elevated basement temperatures and land surface temperatures is 3,5 × 108 kWh/a. This additional heat flow leads to a total geothermal potential which is 2.5 times larger than the estimated annual energy demand for heating and hot water in Vienna.
Evaluation of mineral-aqueous chemical equilibria of felsic reservoirs with low-medium temperature: A comparative study in Yangbajing geothermal field and Guangdong geothermal fields

NASA Astrophysics Data System (ADS)

Li, Jiexiang; Sagoe, Gideon; Yang, Guang; Lu, Guoping

2018-02-01

Classical geothermometers are useful tools for estimating reservoir temperatures of geothermal systems. However, their application to low-medium temperature reservoirs is limited because large variations of temperatures calculated by different classical geothermometers are usually observed. In order to help choose the most appropriate classical geothermometer for calculating the temperatures of low-medium temperature reservoirs, this study evaluated the mineral-aqueous equilibria of typical low-medium temperature felsic reservoirs in the Yangbajing geothermal field and Guangdong geothermal fields. The findings of this study support that reservoirs in the Guangdong geothermal fields have no direct magma influence. Also, natural reservoirs may represent the intermediate steady state before reaching full equilibrium, which rarely occurs. For the low-medium temperature geothermal systems without the influence of magma, even with seawater intrusion, the process of minerals reaching mineral-aqueous equilibrium is sequential: chlorite and chalcedony are the first, then followed by K-feldspar, kaolinite and K-mica. Chlorite may reach equilibrium at varying activity values, and the equilibrium between K-feldspar and kaolinite or K-feldspar and K-mica can fix the contents of K and Al in the solutions. Although the SiO2 and Al attain equilibrium state, albite and laumontite remain unsaturated and thus may affect low-medium temperature calculations. In this study, the chalcedony geothermometer was found to be the most suitable geothermometer for low-medium temperature reservoirs. The results of K-Mg geothermometer may be useful to complement that of the chalcedony geothermometer in low-medium temperature reservoir systems. Na-K geothermometer will give unreliable results at low-medium temperatures; and Na-K-Ca will also be unsuitable to calculate reservoir temperatures lower than 180 °C, probably caused by the chemical imbalance of laumontite.
Sloshing dynamics modulated fluid angular momentum and moment fluctuations driven by orbital gravity gradient and jitter accelerations in microgravity

NASA Technical Reports Server (NTRS)

Hung, R. J.; Pan, H. L.

1995-01-01

The dynamical behavior of spacecraft propellant affected by the asymmetric combined gravity gradient and jitter accelerations, in particular the effect of surface tension on partially-filled rotating fluids applicable to a full-scale Gravity Probe-B Spacecraft dewar tank has been investigated. Three different cases of orbital accelerations: (1) gravity gradient-dominated, (2) equally weighted between gravity gradient and jitter, and (3) gravity jitter-dominated accelerations are studied. The results of slosh wave excitation along the liquid-vapor interface induced by gravity gradient-dominated accelerations provide a torsional moment with tidal motion of bubble oscillations in the rotating dewar. The results are clearly seen from the twisting shape of the bubble oscillations driven by gravity gradient-dominated acceleration. The results of slosh wave excitation along the liquid-vapor interface induced by gravity jitter-dominated acceleration indicate the results of bubble motion in a manner of down-and-up and leftward-and-rightward movement of oscillation when the bubble is rotating with respect to rotating dewar axis. Fluctuations of angular momentum, fluid moment and bubble mass center caused by slosh wave excitations driven by gravity gradient acceleration or gravity jitter acceleration are also investigated.
Bridging worlds/charting new courses

NASA Astrophysics Data System (ADS)

This report describes the work being done within Sandia's renewable energy program. This work touches on four major disciplines. (1) Photovoltaics. The goal of this project is to develop costeffective, reliable energy system technologies for energy supplies worldwide produced by U.S. industry. It encompasses cell research and development, collector development, technology evaluation, systems engineering, domestic and international applications, and design assistance. (2) Solar Thermal. This project endeavors to develop and increase acceptance of solar thermal electric and industrial technologies as cost-competitive candidates for power generation and to promote their commercialization. Its' major activities are with dish/Stirling systems, the Solar Two power tower, design assistance to industry and users, technology development and research activities. (3) Wind. The wind project impacts domestic and international markets with commercially feasible systems for utility-scale and other applications of wind energy. The project conducts applied research in aerodynamics, structural dynamics, fatigue, materials and controls, and engineering systems, and develops cooperative work with industry. (4) Geothermal. This project is developing technology to increase proven geothermal reserves and is assisting industry in expanding geothermal power on-line. Development work is in stemhole drilling, drilling techniques, instrumentation for geothermal wells, acoustic telemetry, and drilling exploratory wells.
Fluid geochemistry of Fault zone hydrothermal system in the Yidun-Litang area, eastern Tibetan Plateau geothermal belt

NASA Astrophysics Data System (ADS)

Shi, Z.; Wang, G.

2017-12-01

Understanding the geochemical and geothermal characteristic of the hydrothermal systems provide useful information in appropriate evaluating the geothermal potential in this area. In this paper, we investigate the chemical and isotopic composition of thermal water in an underexploited geothermal belt, Yidun-Litang area, in eastern Tibetan Plateau geothermal belt. 24 hot springs from the Yidun and Litang area were collected and analyzed. The chemical facies of the hot springs are mainly Na-HCO3 type water. Water-rock interaction, cation exchange are the dominant hydrogeochemical processes in the hydrothermal evolution. All the hot springs show long-time water-rock interaction and significant 18O shift occurred in the Yindun area. Tritium data indicate the long-time water-rock interaction time in the hydrothermal system. According to the isotope and geochemical data, the hydrothermal systems in Yidun and Litang area may share a common deep parent geothermal liquid but receive different sources of meteoric precipitation and undergone different geochemical processes. The Yidun area have relative high reservoir equilibrium temperature (up to 230 °C) while the reservoir temperature at Litang area is relative low (up to 128 °C).
The Efficacy and Potential of Renewable Energy from Carbon Dioxide that is Sequestered in Sedimentary Basin Geothermal Resources

NASA Astrophysics Data System (ADS)

Bielicki, J. M.; Adams, B. M.; Choi, H.; Saar, M. O.; Taff, S. J.; Jamiyansuren, B.; Buscheck, T. A.; Ogland-Hand, J.

2015-12-01

Mitigating climate change requires increasing the amount of electricity that is generated from renewable energy technologies and while simultaneously reducing the amount of carbon dioxide (CO2) that is emitted to the atmosphere from present energy and industrial facilities. We investigated the efficacy of generating electricity using renewable geothermal heat that is extracted by CO2 that is sequestered in sedimentary basins. To determine the efficacy of CO2-Geothermal power production in the United States, we conducted a geospatial resource assessment of the combination of subsurface CO2 storage capacity and heat flow in sedimentary basins and developed an integrated systems model that combines reservoir modeling with power plant modeling and economic costs. The geospatial resource assessment estimates the potential resource base for CO2-Geothermal power plants, and the integrated systems model estimates the physical (e.g., net power) and economic (e.g., levelized cost of electricity, capital cost) performance of an individual CO2-Geothermal power plant for a range of reservoir characteristics (permeability, depth, geothermal temperature gradient). Using coupled inverted five-spot injection patterns that are common in CO2-enhanced oil recovery operations, we determined the well pattern size that best leveraged physical and economic economies of scale for the integrated system. Our results indicate that CO2-Geothermal plants can be cost-effectively deployed in a much larger region of the United States than typical approaches to geothermal electricity production. These cost-effective CO2-Geothermal electricity facilities can also be capacity-competitive with many existing baseload and renewable energy technologies over a range of reservoir parameters. For example, our results suggest that, given the right combination of reservoir parameters, LCOEs can be as low as $25/MWh and capacities can be as high as a few hundred MW.
The hydrothermal-convection systems of Kilauea: An historical perspective

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, R.B.; Kauahikaua, J.P.

1993-08-01

Kilauea is one of only two basaltic volcanoes in the world where geothermal power has been produced commercially. Little is known about the origin, size and longevity of its hydrothermal-convection systems. The authors review the history of scientific studies aimed at understanding these systems and describe their commercial development. Geothermal energy is a controversial issue in Hawaii, partly because of hydrogen sulfide emissions and concerns about protection of rain forests.
ASSESSMENT OF HIGH-TEMPERATURE GEOTHERMAL RESOURCES IN HYDROTHERMAL CONVECTION SYSTEMS IN THE UNITED STATES.

USGS Publications Warehouse

Nathenson, Manuel

1984-01-01

The amount of thermal energy in high-temperature geothermal systems (>150 degree C) in the United States has been calculated by estimating the temperature, area, and thickness of each identified system. These data, along with a general model for recoverability of geothermal energy and a calculation that takes account of the conversion of thermal energy to electricity, yield a resource estimate of 23,000 MWe for 30 years. The undiscovered component was estimated based on multipliers of the identified resource as either 72,000 or 127,000 MWe for 30 years depending on the model chosen for the distribution of undiscovered energy as a function of temperature.
Engineering and economic analysis for the utilization of geothermal fluids in a cane sugar processing plant. Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Humme, J.T.; Tanaka, M.T.; Yokota, M.H.

1979-07-01

The purpose of this study was to determine the feasibility of geothermal resource utilization at the Puna Sugar Company cane sugar processing plant, located in Keaau, Hawaii. A proposed well site area was selected based on data from surface exploratory surveys. The liquid dominated well flow enters a binary thermal arrangement, which results in an acceptable quality steam for process use. Hydrogen sulfide in the well gases is incinerated, leaving sulfur dioxide in the waste gases. The sulfur dioxide in turn is recovered and used in the cane juice processing at the sugar factory. The clean geothermal steam from themore » binary system can be used directly for process requirements. It replaces steam generated by the firing of the waste fibrous product from cane sugar processing. The waste product, called bagasse, has a number of alternative uses, but an evaluation clearly indicated it should continue to be employed for steam generation. This steam, no longer required for process demands, can be directed to increased electric power generation. Revenues gained by the sale of this power to the utility, in addition to other savings developed through the utilization of geothermal energy, can offset the costs associated with hydrothermal utilization.« less
Power-poor Philippines taps geothermal pool

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1982-04-15

The current energy situation in the Philippines (75% imported oil) is reviewed and current and future activities in the area of geothermal energy use is discussed. It is estimated that by 1986, $830 million will be spent to develop the extensive geothermal sources to produce 13% of the nation's total energy. The high-quality geothermal sources are described as producing 162/sup 0/C water-steam mixture at a pressure of 6.68 kg/sec. Energy producing systems are described briefly as well as the environmental and equipment problems encountered already. The cost of geothermal energy is discussed (2.5 cents/kWh) and compared with energy costs ofmore » fossil-fuel and hydroelectricity. It is concluded that the geothermal energy sources should be a major contributor to the Philippines for at least 30 years. (MJJ)« less
Hydrogeochemical exploration of geothermal prospects in the Tecuamburro Volcano region, Guatemala

USGS Publications Warehouse

Janik, C.J.; Goff, F.; Fahlquist, L.; Adams, A.I.; Alfredo, Roldan M.; Chipera, S.J.; Trujillo, P.E.; Counce, D.

1992-01-01

Chemical and isotopic analyses of thermal and nonthermal waters and of gases from springs and fumaroles are used to evaluate the geothermal potential of the Tecuamburro Volcano region, Guatemala. Chemically distinct geothermal surface manifestations generally occur in separate hydrogeologic areas within this 400 km2 region: low-pressure fumaroles with temperatures near local boiling occur at 1470 m elevation in a sulfur mine near the summit of Tecuamburro Volcano; non-boiling acid-sulfate hot springs and mud pots are restricted to the Laguna Ixpaco area, about 5 km NNW of the sulfur mine and 350-400 m lower in elevation; steam-heated and thermal-meteoric waters are found on the flanks of Tecuamburro Volcano and several kilometers to the north in the andesitic highland, where the Infernitos fumarole (97??C at 1180 m) is the primary feature; neutral-chloride hot springs discharge along Rio Los Esclavos, principally near Colmenares at 490 m elevation, about 8-10 km SE of Infernitos. Maximum geothermometer temperatures calculated from Colmenares neutral-chloride spring compositions are ???180??C, whereas maximum subsurface temperatures based on Laguna Ixpaco gas compositions are ???310??C. An exploration core hole drilled to a depth of 808 m about 0.3 km south of Laguna Ixpaco had a bottom-hole temperature of 238??C but did not produce sufficient fluids to confirm or chemically characterize a geothermal reservoir. Hydrogeochemical data combined with regional geologic interpretations indicate that there are probably two hydrothermal-convection systems, which are separated by a major NW-trending structural boundary, the Ixpaco fault. One system with reservoir temperatures near 300??C lies beneath Tecuamburro Volcano and consists of a large vapor zone that feeds steam to the Laguna Ixpaco area, with underlying hot water that flows laterally to feed a small group of warm, chloriderich springs SE of Tecuamburro Volcano. The other system is located beneath the Infernitos area in the andesitic highland and consists of a lower-temperature (150-190??C) reservoir with a large natural discharge that feeds the Colmenares hot springs. ?? 1992.
Combined Geothermal Potential of Subsurface Urban Heat Islands

NASA Astrophysics Data System (ADS)

Benz, Susanne; Bayer, Peter; Menberg, Kathrin; Blum, Philipp

2016-04-01

The subsurface urban heat island (SUHI) can be seen as a geothermal potential in form of elevated groundwater temperatures caused by anthropogenic heat fluxes into the subsurface. In this study, these fluxes are quantified for an annual timeframe in two German cities, Karlsruhe and Cologne. Our two-dimensional (2D) statistical analytical model determines the renewable and sustainable geothermal potential caused by six vertical anthropogenic heat fluxes into the subsurface: from (1) elevated ground surface temperatures, (2) basements, (3) sewage systems, (4) sewage leakage, (5) subway tunnels, and (6) district heating networks. The results show that at present 2.15 ± 1.42 PJ and 0.99 ± 0.32 PJ of heat are annually transported into the shallow groundwater of Karlsruhe and Cologne, respectively, due to anthropogenic heat fluxes into the subsurface. This is sufficient to sustainably cover 32% and 9% of the annual residential space heating demand of Karlsruhe and Cologne, respectively. However, most of the discussed anthropogenic fluxes into the subsurface are conductive heat fluxes and therefore dependent on the groundwater temperature itself. Accordingly, a decrease in groundwater temperature back to its natural (rural) state, achieved through the use of geothermal heat pumps, will increase these fluxes and with them the sustainable potential. Hence, we propose the introduction of a combined geothermal potential that maximizes the sustainability of urban shallow geothermal energy use and the efficiency of shallow geothermal systems by balancing groundwater temperature with anthropogenic heat fluxes into the subsurface. This will be a key element in the development of a demand-oriented, cost-efficient geothermal management tool with an additional focus on the sustainability of the urban heat sources.
On the definition of dominant force regimes for flow boiling heat transfer by using single mini-tubes

NASA Astrophysics Data System (ADS)

Baba, Soumei; Sawada, Kenichiro; Kubota, Chisato; Kawanami, Osamu; Asano, Hitoshi; Inoue, Koichi; Ohta, Haruhiko

Recent increase in the size of space platforms requires the management of larger amount of waste heat under high heat flux conditions and the transportation of it along a long distance to the radiator. Flow boiling applied to the thermal management system in space attracts much attention as promising means to realize high-performance heat transfer and transport because of large latent heat of vaporization. In microgravity two-phase flow phenomena are quite different from those under 1-g condition because buoyancy effects are significantly reduced and surface tension becomes dominant. By the similar reason, flow boiling characteristics in mini channels are not the same as those in channels of normal sizes. In the present stage, however, the boundary between the regimes of body force dominated and of surface tension dominated is not clear. The design of space thermal devices, operated under the conditions where no effect of gravity is expected, will improve the reliability of their ground tests, provided that the boundaries of dominant force regimes are clarified quantitatively in advance. In flow boiling in mini channels or in parallel channels, back flow could be occurred because of rapid growth of bubbles in a confined space, resulting flow rate fluctuation. Flow boiling heat transfer characteristics in mini channels can be changed considerably by the existence of inlet flow rate fluctuation. It is important to pay attention to experimental accuracy and to use a single circular mini-tube to compare heat transfer characteristics with those of normal size tubes. In the present paper, effects of tube orientations, i.e. vertical upward flow, vertical downward flow and horizontal flow, on flow boiling heat transfer characteristics is investigated for FC72 flowing in single mini-tubes with inner diameters of 0.13 and 0.51 mm to establish a reliable dominant force regime map. If the regime map is described by using dimensionless groups of Bond, Weber and Froude numbers, the boundary of dominant forces of inertia and body force is examined by using the mini-tube of the larger diameter at constant Bond number Bo = 0.51, and the boundary of inertia and surface tension by using the mini-tube of smaller diameter at Bo = 0.033. The influence of inertia is varied by the change of vapor quality, i.e. ratio of vapor mass flow rate to the total, under constant mass velocities, where the velocity of liquid-vapor mixtures is increased with increasing vapor quality. For the tube diameter of 0.51 mm, under low inertia conditions at Froude number Fr < 5, heat transfer coefficients were influenced by the tube orientation, while the heat transfer coefficients were almost independent of the orientation for Fr > 5. The results indicated that the boundary between the body force dominated and the inertia force dominated regimes was given by Froude number as Fr ˜ 5. On the other hand, for tube diameter of 0.13 mm, almost no effect of tube = orientation was observed for all combinations of mass velocity and vapor quality, and heat transfer coefficients were independent of vapor quality under low inertia conditions at Weber number We < 5, and vice versa. The results implied the boundary between the surface tension dominated and the inertia force dominated regimes was represented by We ˜ 5. = In addition, by the reflection of both results on the two-dimensional regime map, the boundary between the surface tension dominated and the body force dominated regimes was approx-imately evaluated as Bo ˜ 0.25 from the crossing point of two boundary lines. This value = located in the range of 0.033 < Bo < 0.51 is consistent with the boundaries between the sur-face tension dominated and the body force dominated regimes classified for the smaller and larger mini-tubes, respectively, under low inertia conditions.

Recent trends in the development of heat exchangers for geothermal systems

NASA Astrophysics Data System (ADS)

Franco, A.; Vaccaro, M.

2017-11-01

The potential use of geothermal resources has been a remarkable driver for market players and companies operating in the field of geothermal energy conversion. For this reason, medium to low temperature geothermal resources have been the object of recent rise in consideration, with strong reference to the perspectives of development of Organic Rankine Cycle (ORC) technology. The main components of geothermal plants based on ORC cycle are surely the heat exchangers. A lot of different heat exchangers are required for the operation of ORC plants. Among those it is surely of major importance the Recovery Heat Exchanger (RHE, typically an evaporator), in which the operating fluid is evaporated. Also the Recuperator, in regenerative Organic Rankine Cycle, is of major interest in technology. Another important application of the heat exchangers is connected to the condensation, according to the possibility of liquid or air cooling media availability. The paper analyzes the importance of heat exchangers sizing and the connection with the operation of ORC power plants putting in evidence the real element of innovation: the consideration of the heat exchangers as central element for the optimum design of ORC systems.
Equatorial ground ice on Mars: Steady-state stability

NASA Technical Reports Server (NTRS)

Mellon, Michael T.; Jakosky, Bruce M.; Postawko, Susan E.

1993-01-01

Current Martian equatorial surface temperatures are too warm for water ice to exist at the surface for any appreciable length of time before subliming into the atmosphere. Subsurface temperatures are generally warmer still and, despite the presence of a diffusive barrier of porous regolith material, it has been shown by Smoluchowski, Clifford and Hillel, and Fanale et al. that buried ground ice will also sublime and be lost to the atmosphere in a relatively short time. We investigate the behavior of this subliming subsurface ice and show that it is possible for ice to maintain at a steady-state depth, where sublimation and diffusive loss to the atmosphere is balanced by resupply from beneath by diffusion and recondensation of either a deeper buried ice deposits or ground water. We examine the behavior of equatorial ground ice with a numercial time-marching molecular diffusion model. In our model we allow for diffusion of water vapor through a porous regolith, variations in diffusivity and porosity with ice content, and recondensation of sublimed water vapor. A regolith containing considerable amounts of ice can still be very porous, allowing water vapor to diffuse up from deeper within the ice layer where temperatures are warmer due to the geothermal gradient. This vapor can then recondense nearer to the surface where ice had previously sublimed and been lost to the atmosphere. As a result we find that ice deposits migrate to find a steady-state depth, which represents a balance between diffusive loss to the atmosphere through the overlying porous regolith and diffusive resupply through a porous icy regolith below. This depth depends primarily on the long-term mean surface temperature and the nature of the geothermal gradient, and is independent of the ice-free porosity and the regolith diffusivity. Only the rate of loss of ground ice depends on diffusive properties.
Geomicrobiology of sublacustrine thermal vents in Yellowstone Lake: geochemical controls on microbial community structure and function

PubMed Central

Inskeep, William P.; Jay, Zackary J.; Macur, Richard E.; Clingenpeel, Scott; Tenney, Aaron; Lovalvo, David; Beam, Jacob P.; Kozubal, Mark A.; Shanks, W. C.; Morgan, Lisa A.; Kan, Jinjun; Gorby, Yuri; Yooseph, Shibu; Nealson, Kenneth

2015-01-01

Yellowstone Lake (Yellowstone National Park, WY, USA) is a large high-altitude (2200 m), fresh-water lake, which straddles an extensive caldera and is the center of significant geothermal activity. The primary goal of this interdisciplinary study was to evaluate the microbial populations inhabiting thermal vent communities in Yellowstone Lake using 16S rRNA gene and random metagenome sequencing, and to determine how geochemical attributes of vent waters influence the distribution of specific microorganisms and their metabolic potential. Thermal vent waters and associated microbial biomass were sampled during two field seasons (2007–2008) using a remotely operated vehicle (ROV). Sublacustrine thermal vent waters (circa 50–90°C) contained elevated concentrations of numerous constituents associated with geothermal activity including dissolved hydrogen, sulfide, methane and carbon dioxide. Microorganisms associated with sulfur-rich filamentous “streamer” communities of Inflated Plain and West Thumb (pH range 5–6) were dominated by bacteria from the Aquificales, but also contained thermophilic archaea from the Crenarchaeota and Euryarchaeota. Novel groups of methanogens and members of the Korarchaeota were observed in vents from West Thumb and Elliot's Crater (pH 5–6). Conversely, metagenome sequence from Mary Bay vent sediments did not yield large assemblies, and contained diverse thermophilic and nonthermophilic bacterial relatives. Analysis of functional genes associated with the major vent populations indicated a direct linkage to high concentrations of carbon dioxide, reduced sulfur (sulfide and/or elemental S), hydrogen and methane in the deep thermal ecosystems. Our observations show that sublacustrine thermal vents in Yellowstone Lake support novel thermophilic communities, which contain microorganisms with functional attributes not found to date in terrestrial geothermal systems of YNP. PMID:26579074
Geothermal Geodatabase for Rico Hot Springs Area and Lemon Hot Springs, Dolores and San Miguel Counties, Colorado

DOE Data Explorer

Richard Zehner

2012-11-01

This geodatabase was built to cover several geothermal targets developed by Flint Geothermal in 2012 during a search for high-temperature systems that could be exploited for electric power development. Several of the thermal springs have geochemistry and geothermometry values indicative of high-temperature systems. In addition, the explorationists discovered a very young Climax-style molybdenum porphyry system northeast of Rico, and drilling intersected thermal waters at depth. Datasets include: 1. Structural data collected by Flint Geothermal 2. Point information 3. Mines and prospects from the USGS MRDS dataset 4. Results of reconnaissance shallow (2 meter) temperature surveys 5. Air photo lineaments 6. Areas covered by travertine 7. Groundwater geochemistry 8. Land ownership in the Rico area 9. Georeferenced geologic map of the Rico Quadrangle, by Pratt et al. 10. Various 1:24,000 scale topographic maps
Methanotrophic bacteria in warm geothermal spring sediments identified using stable-isotope probing.

PubMed

Sharp, Christine E; Martínez-Lorenzo, Azucena; Brady, Allyson L; Grasby, Stephen E; Dunfield, Peter F

2014-10-01

We investigated methanotrophic bacteria in sediments of several warm geothermal springs ranging in temperature from 22 to 45 °C. Methane oxidation was measured at potential rates up to 141 μmol CH4 d(-1) g(-1) sediment. Active methanotrophs were identified using (13) CH4 stable-isotope probing (SIP) incubations performed at close to in situ temperatures for each site. Quantitative (q) PCR of pmoA genes identified the position of the heavy ((13) C-labelled) DNA fractions in density gradients, and 16S rRNA gene pyrotag sequencing of the heavy fractions was performed to identify the active methanotrophs. Methanotroph communities identified in heavy fractions of all samples were predominated by species similar (≥ 95% 16S rRNA gene identities) to previously characterized Gammaproteobacteria and Alphaproteobacteria methanotrophs. Among the five hottest samples (45 °C), members of the Gammaproteobacteria genus Methylocaldum dominated in two cases, while three others were dominated by an OTU closely related (96.8% similarity) to the Alphaproteobacteria genus Methylocapsa. These results suggest that diverse methanotroph groups are adapted to warm environments, including the Methylocapsa-Methylocella-Methyloferula group, which has previously only been detected in cooler sites. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.
The impact of temperature on microbial diversity and AOA activity in the Tengchong Geothermal Field, China.

PubMed

Li, Haizhou; Yang, Qunhui; Li, Jian; Gao, Hang; Li, Ping; Zhou, Huaiyang

2015-11-26

Using a culture-independent method that combines CARD-FISH, qPCR and 16S rDNA, we investigated the abundance, community structure and diversity of microbes along a steep thermal gradient (50-90 °C) in the Tengchong Geothermal Field. We found that Bacteria and Archaea abundance changed markedly with temperature changes and that the number of cells was lowest at high temperatures (90.8 °C). Under low-temperature conditions (52.3-74.6 °C), the microbial communities were dominated by Bacteria, which accounted for 60-80% of the total number of cells. At 74.6 °C, Archaea were dominant, and at 90.8 °C, they accounted for more than 90% of the total number of cells. Additionally, the microbial communities at high temperatures (74.6-90.8 °C) were substantially simpler than those at the low-temperature sites. Only a few genera (e.g., bacterial Caldisericum, Thermotoga and Thermoanaerobacter, archaeal Vulcanisaeta and Hyperthermus) often dominated in high-temperature environments. Additionally, a positive correlation between Ammonia-Oxidizing Archaea (AOA) activity and temperature was detected. AOA activity increased from 17 to 52 pmol of NO2(-) per cell d(-1) with a temperature change from 50 to 70 °C.
Unconventional Hydrocarbon Development Hazards Within the Central United States. Report 1: Overview and Potential Risk to Infrastructure

DTIC Science & Technology

2015-08-01

of the injection purpose, i.e., secondary oil and gas recovery, disposal of waste fluids, geothermal energy, and/or UHP hydraulic fracturing...activities such as reservoir impoundment, mining, wastewater injection, geothermal systems and CO2 capture have been linked directly to induced...activities, e.g., deep fluid injection, geothermal injection, and/or UHP wells, that critically affect deep lithologies and alter the existing mechanical
Association of Cancer Incidence and Duration of Residence in Geothermal Heating Area in Iceland: An Extended Follow-Up.

PubMed

Kristbjornsdottir, Adalbjorg; Aspelund, Thor; Rafnsson, Vilhjalmur

2016-01-01

Residents of geothermal areas have higher incidence of non-Hodgkin's lymphoma, breast cancer, prostate cancer, and kidney cancers than others. These populations are exposed to chronic low-level ground gas emissions and various pollutants from geothermal water. The aim was to assess whether habitation in geothermal areas and utilisation of geothermal water is associated with risk of cancer according to duration of residence. The cohort obtained from the census 1981 was followed to the end of 2013. Personal identifier was used in record linkage with nation-wide emigration, death, and cancer registries. The exposed population, defined by community codes, was located on young bedrock and had utilised geothermal water supply systems since 1972. Two reference populations were located by community codes on older bedrock or had not utilised geothermal water supply systems for as long a period as had the exposed population. Adjusted hazard ratio (HR), 95% confidence intervals (CI) non-stratified and stratified on cumulative years of residence were estimated in Cox-model. The HR for all cancer was 1.21 (95% CI 1.12-1.30) as compared with the first reference area. The HR for pancreatic cancer was 1.93 (1.22-3.06), breast cancer, 1.48 (1.23-1.80), prostate cancer 1.47 (1.22-1.77), kidney cancer 1.46 (1.03-2.05), lymphoid and haematopoietic tissue 1.54 (1.21-1.97), non-Hodgkin´s lymphoma 2.08 (1.38-3.15) and basal cell carcinoma of the skin 1.62 (1.35-1.94). Positive dose-response relationship was observed between incidence of cancers and duration of residence, and between incidence of cancer and degree of geothermal/volcanic activity in the comparison areas. The higher cancer incidence in geothermal areas than in reference areas is consistent with previous findings. As the dose-response relationships were positive between incidence of cancers and duration of residence, it is now more urgent than before to investigate the chemical and physical content of the geothermal water and of the ambient air of the areas to detect recognized or new carcinogens.
Long Range Effect of The M7.8 April 2015 Nepal Earth Quake on the Deep Groudwater Outflow in a Thousand-Mile-Away Geothermal Field in Southern China's Guangdong

NASA Astrophysics Data System (ADS)

Lu, G.; Yu, S.; Xu, F.; Wang, X.; Yan, K.; Yuen, D. A.

2015-12-01

Deep ground waters sustain high temperature and pressure and are susceptible to impact from an earthquake. How an earthquake would have been associated with long-range effect on geological environment of deep groundwater is a question of interest to the scientific community and general public. The massive Richter 8.1 Nepal Earthquake (on April 25, 2015) provided a rare opportunity to test the response of deep groundwater systems. Deep ground waters at elevated temperature would naturally flow to ground surface along preferential flow path such as a deep fault, forming geothermal water flows. Geothermal water flows are susceptible to stress variation and can reflect the physical conditions of supercritical hot water kilometers deep down inside the crust. This paper introduces the monitoring work on the outflow in Xijiang Geothermal Field of Xinyi City, Guangdong Province in southern China. The geothermal field is one of typical geothermal fields with deep faults in Guangdong. The geothermal spring has characteristic daily variation of up to 72% in flow rate, which results from being associated with a north-south run deep fault susceptible to earthquake event. We use year-long monitoring data to illustrate how the Nepal earthquake would have affected the flows at the field site over 2.5 thousand kilometers away. The irregularity of flow is judged by deviation from otherwise good correlation of geothermal spring flow with solid earth tidal waves. This work could potentially provide the basis for further study of deep groundwater systems and insight to earthquake prediction.
Geothermal switch heater installation, testing and monitoring : phases 1 & 2.

DOT National Transportation Integrated Search

2016-07-01

Transportation Technology Center, Inc. (TTCI), Norfolk Southern (NS), and John A. Volpe National Transportation Systems Center (Volpe) completed Phases 1 and 2 of a project on a working prototype geothermal switch heating system designed to test the ...
Elements de conception d'un systeme geothermique hybride par optimisation financiere

NASA Astrophysics Data System (ADS)

Henault, Benjamin

The choice of design parameters for a hybrid geothermal system is usually based on current practices or questionable assumptions. In fact, the main purpose of a hybrid geothermal system is to maximize the energy savings associated with heating and cooling requirements while minimizing the costs of operation and installation. This thesis presents a strategy to maximize the net present value of a hybrid geothermal system. This objective is expressed by a series of equations that lead to a global objective function. Iteratively, the algorithm converges to an optimal solution by using an optimization method: the conjugate gradient combined with a combinatorial method. The objective function presented in this paper makes use of a simulation algorithm for predicting the fluid temperature of a hybrid geothermal system on an hourly basis. Thus, the optimization method selects six variables iteratively, continuous and integer type, affecting project costs and energy savings. These variables are the limit temperature at the entry of the heat pump (geothermal side), the number of heat pumps, the number of geothermal wells and the distance in X and Y between the geothermal wells. Generally, these variables have a direct impact on the cost of the installation, on the entering water temperature at the heat pumps, the cost of equipment, the thermal interference between boreholes, the total capacity of geothermal system, on system performance, etc. On the other hand, the arrangement of geothermal wells is variable and is often irregular depending on the number of selected boreholes by the algorithm. Removal or addition of one or more borehole is guided by a predefined order dicted by the designer. This feature of irregular arrangement represents an innovation in the field and is necessary for the operation of this algorithm. Indeed, this ensures continuity between the number of boreholes allowing the use of the conjugate gradient method. The proposed method provides as outputs the net present value of the optimal solution, the position of the vertical boreholes, the number of installed heat pumps, the limits of entering water temperature at the heat pumps and energy consumption of the hybrid geothermal system. To demonstrate the added value of this design method, two case studies are analyzed, for a commercial building and a residential. The two studies allow to conclude that: the net present value of hybrid geothermal systems can be significantly improved by the choice of right specifications; the economic value of a geothermal project is strongly influenced by the number of heat pumps and the number of geothermal wells or the temperature limit in heating mode; the choice of design parameters should always be driven by an objective function and not by the designer; peak demand charges favor hybrid geothermal systems with a higher capacity. Then, in order to validate the operation, this new design method is compared to the standard sizing method which is commonly used. By designing the hybrid geothermal system according to standard sizing method and to meet 70% of peak heating, the net present value over 20 years for the residential project is negative, at -61,500 while it is 43,700 for commercial hybrid geothermal system. Using the new design method presented in this thesis, the net present values of projects are respectively 162,000 and 179,000. The use of this algorithm is beneficial because it significantly increases the net present value of projects. The research presented in this thesis allows to optimize the financial performance of hybrid geothermal systems. The proposed method will allow industry stakeholders to increase the profitability of their projects associated with low temperature geothermal energy.
Liquid-Vapor Interface Configurations Investigated in Low Gravity

NASA Technical Reports Server (NTRS)

Concus, Paul; Finn, Robert; Weislogel, Mark M.

1998-01-01

The Interface Configuration Experiment (ICE) is part of a multifaceted study that is exploring the often striking behavior of liquid-vapor interfaces in low-gravity environments. Although the experiment was posed largely as a test of current mathematical theory, applications of the results should be manifold. In space almost every fluid system is affected, if not dominated, by capillarity (the effects of surface tension). As a result, knowledge of fluid interface behavior, in particular an equilibrium interface shape from which any analysis must begin, is fundamental--from the control of liquid fuels and oxygen in storage tanks to the design and development of inspace thermal systems, such as heat pipes and capillary pumped loops. ICE has increased, and should continue to increase, such knowledge as it probes the specific peculiarities of current theory upon which our present understanding rests. Several versions of ICE have been conducted in the drop towers at the NASA Lewis Research Center, on the space shuttles during the first and second United States Microgravity Laboratory missions (USML-1 and USML-2), and most recently aboard the Russian Mir space station. These studies focused on interfacial problems concerning the existence, uniqueness, configuration, stability, and flow characteristics of liquid-vapor interfaces. Results to date have clearly demonstrated the value of the present theory and the extent to which it can predict the behavior of capillary systems.
Low-Temperature Projects of the Department of Energy's Geothermal Technologies Program: Evaluation and Lessons Learned: Preprint

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Tom; Snyder, Neil; Gosnold, Will

This paper discusses opportunities and challenges related to the technical and economic feasibility of developing power generation from geothermal resources at temperatures of 150 degrees C and lower. Insights from projects funded by the U.S. Department of Energy (DOE), Geothermal Technologies Office inform these discussions and provide the basis for some lessons learned to help guide decisions by DOE and the industry in further developing this resource. The technical basis for low-temperature geothermal energy is well established and the systems can be economic today in certain situations. However, these applications are far from a 'plug and play' product; successful developmentmore » today requires a good knowledge of geothermal system design and operation.« less
Energy Return On Investment of Engineered Geothermal Systems Data

DOE Data Explorer

Mansure, Chip

2012-01-01

The project provides an updated Energy Return on Investment (EROI) for Enhanced Geothermal Systems (EGS). Results incorporate Argonne National Laboratory's Life Cycle Assessment and base case assumptions consistent with other projects in the Analysis subprogram. EROI is a ratio of the energy delivered to the consumer to the energy consumed to build, operate, and decommission the facility. EROI is important in assessing the viability of energy alternatives. Currently EROI analyses of geothermal energy are either out-of-date, of uncertain methodology, or presented online with little supporting documentation. This data set is a collection of files documenting data used to calculate the Energy Return On Investment (EROI) of Engineered Geothermal Systems (EGS) and erratum to publications prior to the final report. Final report is available from the OSTI web site (http://www.osti.gov/geothermal/). Data in this collections includes the well designs used, input parameters for GETEM, a discussion of the energy needed to haul materials to the drill site, the baseline mud program, and a summary of the energy needed to drill each of the well designs. EROI is the ratio of the energy delivered to the customer to the energy consumed to construct, operate, and decommission the facility. Whereas efficiency is the ratio of the energy delivered to the customer to the energy extracted from the reservoir.
Heat flow in vapor dominated areas of the Yellowstone Plateau volcanic field: implications for the thermal budget of the Yellowstone Caldera

USGS Publications Warehouse

Hurwitz, Shaul; Harris, Robert; Werner, Cynthia Anne; Murphy, Fred

2012-01-01

Characterizing the vigor of magmatic activity in Yellowstone requires knowledge of the mechanisms and rates of heat transport between magma and the ground surface. We present results from a heat flow study in two vapor dominated, acid-sulfate thermal areas in the Yellowstone Caldera, the 0.11 km2 Obsidian Pool Thermal Area (OPTA) and the 0.25 km2 Solfatara Plateau Thermal Area (SPTA). Conductive heat flux through a low permeability layer capping large vapor reservoirs is calculated from soil temperature measurements at >600 locations and from laboratory measurements of soil properties. The conductive heat output is 3.6 ± 0.4 MW and 7.5 ± 0.4 MW from the OPTA and the SPTA, respectively. The advective heat output from soils is 1.3 ± 0.3 MW and 1.2 ± 0.3 MW from the OPTA and the SPTA, respectively and the heat output from thermal pools in the OPTA is 6.8 ± 1.4 MW. These estimates result in a total heat output of 11.8 ± 1.4 MW and 8.8 ± 0.4 MW from OPTA and SPTA, respectively. Focused zones of high heat flux in both thermal areas are roughly aligned with regional faults suggesting that faults in both areas serve as conduits for the rising acid vapor. Extrapolation of the average heat flux from the OPTA (103 ± 2 W·m−2) and SPTA (35 ± 3 W·m−2) to the ~35 km2 of vapor dominated areas in Yellowstone yields 3.6 and 1.2 GW, respectively, which is less than the total heat output transported by steam from the Yellowstone Caldera as estimated by the chloride inventory method (4.0 to 8.0 GW).
Geothermal reservoir characterization using distributed temperature sensing at Brady Geothermal Field, Nevada

DOE Office of Scientific and Technical Information (OSTI.GOV)

Patterson, Jeremy R.; Cardiff, Michael; Coleman, Thomas

Distributed temperature sensing (DTS) systems provide near real-time data collection that captures borehole spatiotemporal temperature dynamics. For this study, temperature data was collected in an observation well at an active geothermal site for a period of eight days under geothermal production conditions. Collected temperature data showcase the ability of DTS systems to detect changes to the location of the steam-water interface, visualize borehole temperature recovery — following injection of a coldwater “slug” — and identify anomalously warm and/or cool zones. The high sampling rate and spatial resolution of DTS data also shows borehole temperature dynamics that are not captured bymore » traditional pressure-temperature survey tools. Inversion of thermal recovery data using a finite-difference heat-transfer model produces a thermal-diffusivity profile that is consistent with laboratorymeasured values and correlates with identified lithologic changes within the borehole. Used alone or in conjunction with complementary data sets, DTS systems are useful tools for developing a better understanding of both reservoir rock thermal properties as well as within and near borehole fluid movement.« less
The impact of temperature on microbial diversity and AOA activity in the Tengchong Geothermal Field, China

PubMed Central

Li, Haizhou; Yang, Qunhui; Li, Jian; Gao, Hang; Li, Ping; Zhou, Huaiyang

2015-01-01

Using a culture-independent method that combines CARD-FISH, qPCR and 16S rDNA, we investigated the abundance, community structure and diversity of microbes along a steep thermal gradient (50–90 °C) in the Tengchong Geothermal Field. We found that Bacteria and Archaea abundance changed markedly with temperature changes and that the number of cells was lowest at high temperatures (90.8 °C). Under low-temperature conditions (52.3–74.6 °C), the microbial communities were dominated by Bacteria, which accounted for 60–80% of the total number of cells. At 74.6 °C, Archaea were dominant, and at 90.8 °C, they accounted for more than 90% of the total number of cells. Additionally, the microbial communities at high temperatures (74.6–90.8 °C) were substantially simpler than those at the low-temperature sites. Only a few genera (e.g., bacterial Caldisericum, Thermotoga and Thermoanaerobacter, archaeal Vulcanisaeta and Hyperthermus) often dominated in high-temperature environments. Additionally, a positive correlation between Ammonia-Oxidizing Archaea (AOA) activity and temperature was detected. AOA activity increased from 17 to 52 pmol of NO2− per cell d−1 with a temperature change from 50 to 70 °C. PMID:26608685
The impact of temperature on microbial diversity and AOA activity in the Tengchong Geothermal Field, China

NASA Astrophysics Data System (ADS)

Li, Haizhou; Yang, Qunhui; Li, Jian; Gao, Hang; Li, Ping; Zhou, Huaiyang

2015-11-01

Using a culture-independent method that combines CARD-FISH, qPCR and 16S rDNA, we investigated the abundance, community structure and diversity of microbes along a steep thermal gradient (50-90 °C) in the Tengchong Geothermal Field. We found that Bacteria and Archaea abundance changed markedly with temperature changes and that the number of cells was lowest at high temperatures (90.8 °C). Under low-temperature conditions (52.3-74.6 °C), the microbial communities were dominated by Bacteria, which accounted for 60-80% of the total number of cells. At 74.6 °C, Archaea were dominant, and at 90.8 °C, they accounted for more than 90% of the total number of cells. Additionally, the microbial communities at high temperatures (74.6-90.8 °C) were substantially simpler than those at the low-temperature sites. Only a few genera (e.g., bacterial Caldisericum, Thermotoga and Thermoanaerobacter, archaeal Vulcanisaeta and Hyperthermus) often dominated in high-temperature environments. Additionally, a positive correlation between Ammonia-Oxidizing Archaea (AOA) activity and temperature was detected. AOA activity increased from 17 to 52 pmol of NO2- per cell d-1 with a temperature change from 50 to 70 °C.
Copahue Geothermal System: A Volcanic Environment with Rich Extreme Prokaryotic Biodiversity.

PubMed

Urbieta, María Sofía; Porati, Graciana Willis; Segretín, Ana Belén; González-Toril, Elena; Giaveno, María Alejandra; Donati, Edgardo Rubén

2015-07-08

The Copahue geothermal system is a natural extreme environment located at the northern end of the Cordillera de los Andes in Neuquén province in Argentina. The geochemistry and consequently the biodiversity of the area are dominated by the activity of the Copahue volcano. The main characteristic of Copahue is the extreme acidity of its aquatic environments; ponds and hot springs of moderate and high temperature as well as Río Agrio. In spite of being an apparently hostile location, the prokaryotic biodiversity detected by molecular ecology techniques as well as cultivation shows a rich and diverse environment dominated by acidophilic, sulphur oxidising bacteria or archaea, depending on the conditions of the particular niche studied. In microbial biofilms, found in the borders of the ponds where thermal activity is less intense, the species found are completely different, with a high presence of cyanobacteria and other photosynthetic species. Our results, collected during more than 10 years of work in Copahue, have enabled us to outline geomicrobiological models for the different environments found in the ponds and Río Agrio. Besides, Copahue seems to be the habitat of novel, not yet characterised autochthonous species, especially in the domain Archaea.
Effect of Water Vapor Pressure on Fatigue Crack Growth in Al-Zn-Cu-Mg Alloy Over Wide-Range Stress Intensity Factor Loading

DTIC Science & Technology

2014-05-07

impacts: (a) crack closure, (b) transport of water vapor molecules within the fatigue crack (47], and (c) tensile stress-plastic strain range...sealed stainless steel UHV chamber. Pure water vapor was introduced from a sealed glass flask containing triply distilled water, via a precision leak...lamellar for H1 flow in a fatigue crack in steel ; specifically, flow is dominated by the low dynamic viscosity of a gas (particularly at low pressures) and

Chlorite, Biotite, Illite, Muscovite, and Feldspar Dissolution Kinetics at Variable pH and Temperatures up to 280 C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carroll, S.; Smith, M.; Lammers, K.

2016-10-05

Summary Sheet silicates and clays are ubiquitous in geothermal environments. Their dissolution is of interest because this process contributes to scaling reactions along fluid pathways and alteration of fracture surfaces, which could affect reservoir permeability. In order to better predict the geochemical impacts on long-term performance of engineered geothermal systems, we have measured chlorite, biotite, illite, and muscovite dissolution and developed generalized kinetic rate laws that are applicable over an expanded range of solution pH and temperature for each mineral. This report summarizes the rate equations for layered silicates where data were lacking for geothermal systems.
Geothermal Energy Summary

DOE Office of Scientific and Technical Information (OSTI.GOV)

J. L. Renner

2007-08-01

Following is complete draft.Geothermal Summary for AAPG Explorer J. L. Renner, Idaho National Laboratory Geothermal energy is used to produce electricity in 24 countries. The United States has the largest capacity (2,544 MWe) followed by Philippines (1,931 MWe), Mexico (953 MWe), Indonesia (797 MWe), and Italy (791 MWe) (Bertani, 2005). When Chevron Corporation purchased Unocal Corporation they became the leading producer of geothermal energy worldwide with projects in Indonesia and the Philippines. The U. S. geothermal industry is booming thanks to increasing energy prices, renewable portfolio standards, and a production tax credit. California (2,244 MWe) is the leading producer, followedmore » by Nevada (243 MWe), Utah (26 MWe) and Hawaii (30 MWe) and Alaska (0.4 MWe) (Bertani, 2005). Alaska joined the producing states with two 0.4 KWe power plants placed on line at Chena Hot Springs during 2006. The plant uses 30 liters per second of 75°C water from shallow wells. Power production is assisted by the availability of gravity fed, 7°C cooling water (http://www.yourownpower.com/) A 13 MWe binary power plant is expected to begin production in the fall of 2007 at Raft River in southeastern Idaho. Idaho also is a leader in direct use of geothermal energy with the state capital building and several other state and Boise City buildings as well as commercial and residential space heated using fluids from several, interconnected geothermal systems. The Energy Policy Act of 2005 modified leasing provisions and royalty rates for both geothermal electrical production and direct use. Pursuant to the legislation the Bureau of Land management and Minerals Management Service published final regulations for continued geothermal leasing, operations and royalty collection in the Federal Register (Vol. 72, No. 84 Wednesday May 2, 2007, BLM p. 24358-24446, MMS p. 24448-24469). Existing U. S. plants focus on high-grade geothermal systems located in the west. However, interest in non-traditional geothermal development is increasing. A comprehensive new MIT-led study of the potential for geothermal energy within the United States predicts that mining the huge amounts of stored thermal energy in the Earth’s crust not associated with hydrothermal systems, could supply a substantial portion of U.S. electricity with minimal environmental impact (Tester, et al., 2006, available at http://geothermal.inl.gov). There is also renewed interest in geothermal production from other non-traditional sources such as the overpressured zones in the Gulf Coast and warm water co-produced with oil and gas. Ormat Technologies, Inc., a major geothermal company, recently acquired geothermal leases in the offshore overpressured zone of Texas. Ormat and the Rocky Mountain Oilfield Testing Center recently announced plans to jointly produce geothermal power from co-produced water from the Teapot Dome oilfield (Casper Star-Tribune, March 2, 2007). RMOTC estimates that 300 KWe capacity is available from the 40,000 BWPD of 88°C water associated with oil production from the Tensleep Sandstone (Milliken, 2007). The U. S. Department of Energy is seeking industry partners to develop electrical generation at other operating oil and gas fields (for more information see: https://e-center.doe.gov/iips/faopor.nsf/UNID/50D3734745055A73852572CA006665B1?OpenDocument). Several web sites offer periodically updated information related to the geothermal industry and th« less
Influence of geology on arsenic concentrations in ground and surface water in central Lesvos, Greece.

PubMed

Aloupi, Maria; Angelidis, Michael O; Gavriil, Apostolos M; Koulousaris, Michael; Varnavas, Soterios P

2009-04-01

The occurrence of As was studied in groundwater used for human consumption and irrigation, in stream water and sediments and in water from thermal springs in the drainage basin of Kalloni Gulf, island of Lesvos, Greece, in order to investigate the potential influence of the geothermal field of Polichnitos-Lisvori on the ground and surface water systems of the area. Total dissolved As varied in the range <0.7-88.3 microg L(-1) in groundwater, 41.1-90.7 microg L(-1) in thermal spring water and 0.4-13.2 microg L(-1) in stream water, whereas As concentrations in stream sediments varied between 2.0-21.9 mg kg(-1). Four out of 31 groundwater samples exceeded the EC standard of 10 microg L(-1). The survey revealed an enrichment in both surface and groundwater hydrological systems in the northern part of the area (average concentrations of As in groundwater, stream water and stream sediment: 8.0 microg L(-1), 8.8 microg L(-1) and 15.0 mg kg(-1) respectively), in association with the volcanic bedrocks, while lower As concentrations were found in the eastern part (average concentrations in groundwater, stream water and stream sediment: 2.9 microg L(-1), 1.7 microg L(-1) and 5.9 mg kg(-1) respectively), which is dominated by ophiolitic ultramafic formations. The variation of As levels between the different parts of the study area suggests that local geology exerts a determinant influence on As geochemical behaviour. On the other hand, the geothermal activity manifested in the area of Polichnitos-Lisvori does not affect the presence of As in groundwater and streams.
Copahue Geothermal System: A Volcanic Environment with Rich Extreme Prokaryotic Biodiversity

PubMed Central

Urbieta, María Sofía; Willis Porati, Graciana; Segretín, Ana Belén; González-Toril, Elena; Giaveno, María Alejandra; Donati, Edgardo Rubén

2015-01-01

The Copahue geothermal system is a natural extreme environment located at the northern end of the Cordillera de los Andes in Neuquén province in Argentina. The geochemistry and consequently the biodiversity of the area are dominated by the activity of the Copahue volcano. The main characteristic of Copahue is the extreme acidity of its aquatic environments; ponds and hot springs of moderate and high temperature as well as Río Agrio. In spite of being an apparently hostile location, the prokaryotic biodiversity detected by molecular ecology techniques as well as cultivation shows a rich and diverse environment dominated by acidophilic, sulphur oxidising bacteria or archaea, depending on the conditions of the particular niche studied. In microbial biofilms, found in the borders of the ponds where thermal activity is less intense, the species found are completely different, with a high presence of cyanobacteria and other photosynthetic species. Our results, collected during more than 10 years of work in Copahue, have enabled us to outline geomicrobiological models for the different environments found in the ponds and Río Agrio. Besides, Copahue seems to be the habitat of novel, not yet characterised autochthonous species, especially in the domain Archaea. PMID:27682093
Estimation of the geothermal potential of the Caldara di Manziana site in the Mts Sabatini Volcanic District (Central Italy) by integrating geochemical data and 3D-GIS modelling.

NASA Astrophysics Data System (ADS)

Ranaldi, Massimo; Lelli, Matteo; Tarchini, Luca; Carapezza, Maria Luisa; Patera, Antonio

2016-04-01

High-enthalpy geothermal fields of Central Italy are hosted in deeply fractured carbonate reservoirs occurring in thermally anomalous and seismically active zones. However, the Mts. Sabatini volcanic district, located north of Rome, has an interesting deep temperatures (T), but it is characterized by low to very low seismicity and permeability in the reservoir rocks (mostly because of hydrothermal self-sealing processes). Low PCO2 facilitates the complete sealing of the reservoir fractures, preventing hot fluids rising and, determining a low CO2 flux at the surface. Conversely, high CO2 flux generally reflects a high pressure of CO2, suggesting that an active geothermal reservoir is present at depth. In Mts. Sabatini district, the Caldara of Manziana (CM) is the only zone characterized by a very high CO2 flux (188 tons/day) from a surface of 0.15 km2) considering both the diffuse and viscous CO2 emission. This suggests the likely presence of an actively degassing geothermal reservoir at depth. Emitted gas is dominated by CO2 (>97 vol.%). Triangular irregular networks (TINs) have been used to represent the morphology of the bottom of the surficial volcanic deposits, the thickness of the impervious formation and the top of the geothermal reservoir. The TINs, integrated by T-gradient and deep well data, allowed to estimate the depth and the temperature of the top of the geothermal reservoir, respectively to ~-1000 m from the surface and to ~130°C. These estimations are fairly in agreement with those obtained by gas chemistry (818
From Crustal Anatexis to Pluton Emplacement: High-Precision Zircon Geochronology Reveals the Thermal History of the Larderello-Travale Geothermal System (Italy)

NASA Astrophysics Data System (ADS)

Farina, F.; Dini, A.; Ovtcharova, M.; Davies, J.; Bouvier, A. S.; Baumgartner, L. P.; Caricchi, L.; Schaltegger, U.

2017-12-01

Late Miocene to recent post-collisional extension in Tuscany (Italy) led to the emplacement of shallow-level granitic plutons and to the eruption of small rhyolitic bodies. The intrusion of peraluminous two-mica and tourmaline-bearing granites triggered the formation of the steam-dominated Larderello-Travale geothermal system. In this study, zircon crystals from granite samples obtained from drill holes at 3.0-4.5 km depth were investigated by combining in-situ oxygen isotopes analysis and high-precision CA-ID-TIMS U-Pb age determinations to gain insight into the nature of the magmatic heat source fuelling the geothermal field. Magmatic zircon crystals display δ18O values ranging from 8.6 to 13.5‰ and crystals from individual samples exhibit inter- and intra-grain oxygen isotope variability exceeding 3‰. The geochronological data indicates the existence of three magmatic pulses with ages between 3.637 ± 0.008 and 1.671 ± 0.004 Ma. More importantly, zircon crystals from individual samples exhibit an age spread as large as 200-400 ky. This age dispersion, which is more than one order of magnitude greater than the uncertainty on a single date, suggest that most of the zircon did not crystallize at the emplacement level, but within isolated and isotopically distinct magma batches before large-scale homogenization in a magmatic reservoir at depth. The rate of assembly and final volume of this reservoir is estimated using the distribution of precise U-Pb zircon dates following the approach of Caricchi et al. (2014). Thermal modelling indicates that the heat flow at the surface in the geothermal field cannot be sustained by the inferred reservoir or by heat advection from the mantle. Our data suggest the existence of a younger shallow-level intrusion, whose occurrence also accounts for the existence of confined magmatic fluids at the top of the Larderello-Travale intrusion. We conclude that a multi-disciplinary approach, integrating high-precision zircon dating, in-situ oxygen isotopes and thermal modelling can be used to resolve the thermal structure of the crust in active geothermal systems. Ref: Caricchi et al., (2014). Nature, 511, 457-461. This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 701494.
Analytical model for the design of in situ horizontal permeable reactive barriers (HPRBs) for the mitigation of chlorinated solvent vapors in the unsaturated zone

NASA Astrophysics Data System (ADS)

Verginelli, Iason; Capobianco, Oriana; Hartog, Niels; Baciocchi, Renato

2017-02-01

In this work we introduce a 1-D analytical solution that can be used for the design of horizontal permeable reactive barriers (HPRBs) as a vapor mitigation system at sites contaminated by chlorinated solvents. The developed model incorporates a transient diffusion-dominated transport with a second-order reaction rate constant. Furthermore, the model accounts for the HPRB lifetime as a function of the oxidant consumption by reaction with upward vapors and its progressive dissolution and leaching by infiltrating water. Simulation results by this new model closely replicate previous lab-scale tests carried out on trichloroethylene (TCE) using a HPRB containing a mixture of potassium permanganate, water and sand. In view of field applications, design criteria, in terms of the minimum HPRB thickness required to attenuate vapors at acceptable risk-based levels and the expected HPRB lifetime, are determined from site-specific conditions such as vapor source concentration, water infiltration rate and HPRB mixture. The results clearly show the field-scale feasibility of this alternative vapor mitigation system for the treatment of chlorinated solvents. Depending on the oxidation kinetic of the target contaminant, a 1 m thick HPRB can ensure an attenuation of vapor concentrations of orders of magnitude up to 20 years, even for vapor source concentrations up to 10 g/m3. A demonstrative application for representative contaminated site conditions also shows the feasibility of this mitigation system from an economical point of view with capital costs potentially somewhat lower than those of other remediation options, such as soil vapor extraction systems. Overall, based on the experimental and theoretical evaluation thus far, field-scale tests are warranted to verify the potential and cost-effectiveness of HPRBs for vapor mitigation control under various conditions of application.
Geothermal resources of California sedimentary basins

USGS Publications Warehouse

Williams, C.F.; Grubb, F.V.; Galanis, S.P.

2004-01-01

The 2004 Department of Energy (DOE) Strategic Plan for geothermal energy calls for expanding the geothermal resource base of the United States to 40,000 MW of electric power generating potential. This will require advances in technologies for exploiting unconventional geothermal resources, including Enhanced Geothermal Systems (EGS) and geopressured geothermal. An investigation of thermal conditions in California sedimentary basins through new temperature and heat flow measurements reveals significant geothermal potential in some areas. In many of the basins, the combined cooling effects of recent tectonic and sedimentary processes result in relatively low (<60 mW/m2) heat flow and geothermal gradients. For example, temperatures in the upper 3 km of San Joaquin, Sacramento and Ventura basins are typically less than 125??C and do not reach 200??c by 5 km. By contrast, in the Cuyama, Santa Maria and western Los Angeles basins, heat flow exceeds 80 mW/m2 and temperatures near or above 200??C occur at 4 to 5 km depth, which represents thermal conditions equivalent to or hotter than those encountered at the Soultz EGS geothermal site in Europe. Although the extractable geothermal energy contained in these basins is not large relative to the major California producing geothermal fields at The Geysers or Salton Sea, the collocation in the Los Angeles basin of a substantial petroleum extraction infrastructure and a major metropolitan area may make it attractive for eventual geothermal development as EGS technology matures.
A Review of Methods Applied by the U.S. Geological Survey in the Assessment of Identified Geothermal Resources

USGS Publications Warehouse

Williams, Colin F.; Reed, Marshall J.; Mariner, Robert H.

2008-01-01

The U. S. Geological Survey (USGS) is conducting an updated assessment of geothermal resources in the United States. The primary method applied in assessments of identified geothermal systems by the USGS and other organizations is the volume method, in which the recoverable heat is estimated from the thermal energy available in a reservoir. An important focus in the assessment project is on the development of geothermal resource models consistent with the production histories and observed characteristics of exploited geothermal fields. The new assessment will incorporate some changes in the models for temperature and depth ranges for electric power production, preferred chemical geothermometers for estimates of reservoir temperatures, estimates of reservoir volumes, and geothermal energy recovery factors. Monte Carlo simulations are used to characterize uncertainties in the estimates of electric power generation. These new models for the recovery of heat from heterogeneous, fractured reservoirs provide a physically realistic basis for evaluating the production potential of natural geothermal reservoirs.
Volcanostratigraphic Approach for Evaluation of Geothermal Potential in Galunggung Volcano

NASA Astrophysics Data System (ADS)

Ramadhan, Q. S.; Sianipar, J. Y.; Pratopo, A. K.

2016-09-01

he geothermal systems in Indonesia are primarily associated with volcanoes. There are over 100 volcanoes located on Sumatra, Java, and in the eastern part of Indonesia. Volcanostratigraphy is one of the methods that is used in the early stage for the exploration of volcanic geothermal system to identify the characteristics of the volcano. The stratigraphy of Galunggung Volcano is identified based on 1:100.000 scale topographic map of Tasikmalaya sheet, 1:50.000 scale topographic map and also geological map. The schematic flowchart for evaluation of geothermal exploration is used to interpret and evaluate geothermal potential in volcanic regions. Volcanostratigraphy study has been done on Galunggung Volcano and Talaga Bodas Volcano, West Java, Indonesia. Based on the interpretation of topographic map and analysis of the dimension, rock composition, age and stress regime, we conclude that both Galunggung Volcano and Talaga Bodas Volcano have a geothermal resource potential that deserve further investigation.
Topographic and Air-Photo Lineaments in Various Locations Related to Geothermal Exploration in Colorado

DOE Data Explorer

Richard Zehner

2012-02-01

These line shapefiles trace apparent topographic and air-photo lineaments in various counties in Colorado. It was made in order to identify possible fault and fracture systems that might be conduits for geothermal fluids, as part of a DOE reconnaissance geothermal exploration program. Geothermal fluids commonly utilize fault and fractures in competent rocks as conduits for fluid flow. Geothermal exploration involves finding areas of high near-surface temperature gradients, along with a suitable "plumbing system" that can provide the necessary permeability. Geothermal power plants can sometimes be built where temperature and flow rates are high. This line shapefile is an attempt to use desktop GIS to delineate possible faults and fracture orientations and locations in highly prospective areas prior to an initial site visit. Geochemical sampling and geologic mapping could then be centered around these possible faults and fractures. To do this, georeferenced topographic maps and aerial photographs were utilized in an existing GIS, using ESRI ArcMap 10.0 software. The USA_Topo_Maps and World_Imagery map layers were chosen from the GIS Server at server.arcgisonline.com, using a UTM Zone 13 NAD27 projection. This line shapefile was then constructed over that which appeared to be through-going structural lineaments in both the aerial photographs and topographic layers, taking care to avoid manmade features such as roads, fence lines, and utility right-of-ways. Still, it is unknown what actual features these lineaments, if they exist, represent. Although the shapefiles are arranged by county, not all areas within any county have been examined for lineaments. Work was focused on either satellite thermal infrared anomalies, known hot springs or wells, or other evidence of geothermal systems. Finally, lineaments may be displaced somewhat from their actual location, due to such factors as shadow effects with low sun angles in the aerial photographs. Credits: These lineament shapefile was created by Geothermal Development Associates, as part of a geothermal geologic reconnaissance performed by Flint Geothermal, LLC, of Denver Colorado. Use Limitation: These shapefiles were constructed as an aid to geothermal exploration in preparation for a site visit for field checking. We make no claims as to the existence of the lineaments, their location, orientation, and/or nature.
Finite-element solutions for geothermal systems

NASA Technical Reports Server (NTRS)

Chen, J. C.; Conel, J. E.

1977-01-01

Vector potential and scalar potential are used to formulate the governing equations for a single-component and single-phase geothermal system. By assuming an initial temperature field, the fluid velocity can be determined which, in turn, is used to calculate the convective heat transfer. The energy equation is then solved by considering convected heat as a distributed source. Using the resulting temperature to compute new source terms, the final results are obtained by iterations of the procedure. Finite-element methods are proposed for modeling of realistic geothermal systems; the advantages of such methods are discussed. The developed methodology is then applied to a sample problem. Favorable agreement is obtained by comparisons with a previous study.
MISR Observations of Etna Volcanic Plumes

NASA Technical Reports Server (NTRS)

Scollo, S.; Kahn, R. A.; Nelson, D. L.; Coltelli, M.; Diner, D. J.; Garay, M. J.; Realmuto, V. J.

2012-01-01

In the last twelve years, Mt. Etna, located in eastern Sicily, has produced a great number of explosive eruptions. Volcanic plumes have risen to several km above sea level and created problems for aviation and the communities living near the volcano. A reduction of hazards may be accomplished using remote sensing techniques to evaluate important features of volcanic plumes. Since 2000, the Multiangle Imaging SpectroRadiometer (MISR) on board NASA s Terra spacecraft has been extensively used to study aerosol dispersal and to extract the three-dimensional structure of plumes coming from anthropogenic or natural sources, including volcanoes. In the present work, MISR data from several explosive events occurring at Etna are analyzed using a program named MINX (MISR INteractive eXplorer). MINX uses stereo matching techniques to evaluate the height of the volcanic aerosol with a precision of a few hundred meters, and extracts aerosol properties from the MISR Standard products. We analyzed twenty volcanic plumes produced during the 2000, 2001, 2002-03, 2006 and 2008 Etna eruptions, finding that volcanic aerosol dispersal and column height obtained by this analysis is in good agreement with ground-based observations. MISR aerosol type retrievals: (1) clearly distinguish volcanic plumes that are sulphate and/or water vapor dominated from ash-dominated ones; (2) detect even low concentrations of volcanic ash in the atmosphere; (3) demonstrate that sulphate and/or water vapor dominated plumes consist of smaller-sized particles compared to ash plumes. This work highlights the potential of MISR to detect important volcanic plume characteristics that can be used to constrain the eruption source parameters in volcanic ash dispersion models. Further, the possibility of discriminating sulphate and/or water vapor dominated plumes from ash-dominated ones is important to better understand the atmospheric impact of these plumes.
Cumulative biological impacts of The Geysers geothermal development

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brownell, J.A.

1981-10-01

The cumulative nature of current and potential future biological impacts from full geothermal development in the steam-dominated portion of The Geysers-Calistoga KGRA are identified by the California Energy Commission staff. Vegetation, wildlife, and aquatic resources information have been reviewed and evaluated. Impacts and their significance are discussed and staff recommendations presented. Development of 3000 MW of electrical energy will result in direct vegetation losses of 2790 acres, based on an estimate of 11.5% loss per lease-hold of 0.93 acres/MW. If unmitigated, losses will be greater. Indirect vegetation losses and damage occur from steam emissions which contain elements (particularly boron) toxicmore » to vegetation. Other potential impacts include chronic low-level boron exposure, acid rain, local climate modification, and mechanical damage. A potential exists for significant reduction and changes in wildlife from direct habitat loss and development influences. Highly erosive soils create the potential for significant reduction of aquatic resources, particularly game fish. Toxic spills have caused some temporary losses of aquatic species. Staff recommends monitoring and implementation of mitigation measures at all geothermal development stages.« less
Subsurface modeling of geothermal manifestation in Mt. Endut based on vertical electrical sounding (VES) method

NASA Astrophysics Data System (ADS)

Permadi, A. N.; Akbar, A. M.; Wildan, D.; Sobirin, R.; Supriyanto

2017-07-01

The Endut geothermal prospect area is located in Lebak district, Banten province, about 40 km in the southern Rangkasbitung city. This area has been surveyed by PSDG (Pusat Sumber Daya Geologi) since 2006. In this survey, data acquisition has been performed by using the resistivity methods with Schlumberger configuration from southwest to northeast. Local hot spring Cikawah (CKW) manifestation dominated by quaternary volcanic rocks of Mount Endut product that intruded tertiary sedimentary bedrock. Horizontal fault and normal trend rejuvenation of the northeast - southwest was expected control hot spring manifestation in Cikawah. Geothermal manifestations such as hot water Cikawah has the highest temperature (88 °C), the hot water discharge 5 L/sec, neutral pH, chloride type, in partial equlibrium, and there are in the between of the balance of Cl-Li-B. Resistivity data shows conductive layer at a depth of approximately 500 meters below Cikawah hot spring, which is suspected to be associated with the argillic alteration intrusive rocks. The high resistivity anomaly is suspected to be associated with thick igneous intrusive rocks.
Critiquing ';pore connectivity' as basis for in situ flow in geothermal systems

NASA Astrophysics Data System (ADS)

Kenedi, C. L.; Leary, P.; Malin, P.

2013-12-01

Geothermal system in situ flow systematics derived from detailed examination of grain-scale structures, fabrics, mineral alteration, and pore connectivity may be extremely misleading if/when extrapolated to reservoir-scale flow structure. In oil/gas field clastic reservoir operations, it is standard to assume that small scale studies of flow fabric - notably the Kozeny-Carman and Archie's Law treatments at the grain-scale and well-log/well-bore sampling of formations/reservoirs at the cm-m scale - are adequate to define the reservoir-scale flow properties. In the case of clastic reservoirs, however, a wide range of reservoir-scale data wholly discredits this extrapolation: Well-log data show that grain-scale fracture density fluctuation power scales inversely with spatial frequency k, S(k) ~ 1/k^β, 1.0 < β < 1.2, 1cycle/km < k < 1cycle/cm; the scaling is a ';universal' feature of well-logs (neutron porosity, sonic velocity, chemical abundance, mass density, resistivity, in many forms of clastic rock and instances of shale bodies, for both horizontal and vertical wells). Grain-scale fracture density correlates with in situ porosity; spatial fluctuations of porosity φ in well-core correlate with spatial fluctuations in the logarithm of well-core permeability, δφ ~ δlog(κ) with typical correlation coefficient ~ 85%; a similar relation is observed in consolidating sediments/clays, indicating a generic coupling between fluid pressure and solid deformation at pore sites. In situ macroscopic flow systems are lognormally distributed according to κ ~ κ0 exp(α(φ-φ0)), α >>1 an empirical parameter for degree of in situ fracture connectivity; the lognormal distribution applies to well-productivities in US oil fields and NZ geothermal fields, ';frack productivity' in oil/gas shale body reservoirs, ore grade distributions, and trace element abundances. Although presently available evidence for these properties in geothermal reservoirs is limited, there are indications that geothermal system flow essentially obeys the same ';universal' in situ flow rules as does clastic rock: Well-log data from Los Azufres, MX, show power-law scaling S(k) ~ 1/k^β, 1.2 < β < 1.4, for spatial frequency range 2cycles/km to 0.5cycle/m; higher β-values are likely due to the relatively fresh nature of geothermal systems; Well-core at Bulalo (PH) and Ohaaki (NZ) show statistically significant spatial correlation, δφ ~ δlog(κ) Well productivity at Ohaaki/Ngawha (NZ) and in geothermal systems elsewhere are lognormally distributed; K/Th/U abundances lognormally distributed in Los Azufres well-logs We therefore caution that small-scale evidence for in situ flow fabric in geothermal systems that is interpreted in terms of ';pore connectivity' may in fact not reflect how small-scale chemical processes are integrated into a large-scale geothermal flow structure. Rather such small scale studies should (perhaps) be considered in term of the above flow rules. These flow rules are easily incorporated into standard flow simulation codes, in particular the OPM = Open Porous Media open-source industry-standard flow code. Geochemical transport data relevant to geothermal systems can thus be expected to be well modeled by OPM or equivalent (e.g., INL/LANL) codes.
The Coso geothermal area: A laboratory for advanced MEQ studies for geothermal monitoring

USGS Publications Warehouse

Julian, B.R.; Foulger, G.R.; Richards-Dinger, K.

2004-01-01

The permanent 16-station network of three-component digital seismometers at the Coso geothermal area, California, supplemented by 14 temporary instruments deployed in connection with the DOE Enhanced Geothermal Systems (EGS) Project, provides high-quality microearthquake (MEQ) recordings that are well suited to monitoring a producing geothermal area. We are currently using these data to investigate structure and active processes within the geothermal reservoir by applying three advanced methods: a) high-precision MEQ hypocenter location; b) time-dependent tomography; c) complete (moment tensor) MEQ source mechanism determination. Preliminary results to date resolve seismogenic structures in the producing field more clearly than is possible with conventional earthquake-location techniques. A shallow part of the producing field shows clear changes in the ratio of the seismic wave speeds, Vp/V s, between 1996 and 2002, which are probably related to physical changes in the reservoir caused by fluid extraction.
Archaeal and bacterial diversity in two hot spring microbial mats from a geothermal region in Romania.

PubMed

Coman, Cristian; Drugă, Bogdan; Hegedus, Adriana; Sicora, Cosmin; Dragoş, Nicolae

2013-05-01

The diversity of archaea and bacteria was investigated in two slightly alkaline, mesophilic hot springs from the Western Plain of Romania. Phylogenetic analysis showed a low diversity of Archaea, only three Euryarchaeota taxa being detected: Methanomethylovorans thermophila, Methanomassiliicoccus luminyensis and Methanococcus aeolicus. Twelve major bacterial groups were identified, both springs being dominated by Cyanobacteria, Chloroflexi and Proteobacteria. While at the phylum/class-level the microbial mats share a similar biodiversity; at the species level the geothermal springs investigated seem to be colonized by specific consortia. The dominant taxa were filamentous heterocyst-containing Fischerella, at 45 °C and non-heterocyst Leptolyngbya and Geitlerinema, at 55 °C. Other bacterial taxa (Thauera sp., Methyloversatilis universalis, Pannonibacter phragmitetus, Polymorphum gilvum, Metallibacterium sp. and Spartobacteria) were observed for the first time in association with a geothermal habitat. Based on their bacterial diversity the two mats were clustered together with other similar habitats from Europe and part of Asia, most likely the water temperature playing a major role in the formation of specific microbial communities that colonize the investigated thermal springs.
Geothermal pilot study final report: creating an international geothermal energy community

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bresee, J.C.; Yen, W.W.S.; Metzler, J.E.

The Geothermal Pilot Study under the auspices of the Committee on the Challenges of Modern Society (CCMS) was established in 1973 to apply an action-oriented approach to international geothermal research and development, taking advantage of the established channels of governmental communication provided by the North Atlantic Treaty Organization (NATO). The Pilot Study was composed of five substudies. They included: computer-based information systems; direct application of geothermal energy; reservoir assessment; small geothermal power plants; and hot dry rock concepts. The most significant overall result of the CCMS Geothermal Pilot Study, which is now complete, is the establishment of an identifiable communitymore » of geothermal experts in a dozen or more countries active in development programs. Specific accomplishments include the creation of an international computer file of technical information on geothermal wells and fields, the development of studies and reports on direct applications, geothermal fluid injection and small power plants, and the operation of the visiting scientist program. In the United States, the computer file has aready proven useful in the development of reservoir models and of chemical geothermometers. The state-of-the-art report on direct uses of geothermal energy is proving to be a valuable resource document for laypersons and experts in an area of increasing interest to many countries. Geothermal fluid injection studies in El Salvador, New Zealand, and the United States have been assisted by the Reservoir Assessment Substudy and have led to long-range reservoir engineering studies in Mexico. At least seven small geothermal power plants are in use or have been planned for construction around the world since the Small Power Plant Substudy was instituted--at least partial credit for this increased application can be assigned to the CCMS Geothermal Pilot Study. (JGB)« less
Deep permeable fault-controlled helium transport and limited mantle flux in two extensional geothermal systems in the Great Basin, United States

USGS Publications Warehouse

Banerjee, Amlan; Person, Mark; Hofstra, Albert; Sweetkind, Donald S.; Cohen, Denis; Sabin, Andrew; Unruh, Jeff; Zyvoloski, George; Gable, Carl W.; Crossey, Laura; Karlstrom, Karl

2011-01-01

This study assesses the relative importance of deeply circulating meteoric water and direct mantle fluid inputs on near-surface 3He/4He anomalies reported at the Coso and Beowawe geothermal fields of the western United States. The depth of meteoric fluid circulation is a critical factor that controls the temperature, extent of fluid-rock isotope exchange, and mixing with deeply sourced fluids containing mantle volatiles. The influence of mantle fluid flux on the reported helium anomalies appears to be negligible in both systems. This study illustrates the importance of deeply penetrating permeable fault zones (10-12 to 10-15 m2) in focusing groundwater and mantle volatiles with high 3He/4He ratios to shallow crustal levels. These continental geothermal systems are driven by free convection.

A biographical memoir of Donald Edward White

USGS Publications Warehouse

Muffler, L. J. Patrick

2016-01-01

Donald E. White was a leading scientist for the U.S. Geological Survey, where his career was devoted almost entirely to the study of hydrothermal processes in the Earth’s crust, from the dual perspectives of active geothermal systems and of extinct hydrothermal systems now represented only by ore deposits and alteration patterns. White was devoted to analyzing the mechanisms by which ore-forming metals are concentrated, transported, and deposited. His early work on antimony deposits and on mercury transport led to the understanding that these elements, as well as some precious metals, were concentrated in hydrothermal convection systems characterized by dilute chloride waters of predominantly meteoric origin. He concluded, on the other hand, that base metals required more concentrated brines, as was impressively confirmed in the early 1960s by the discovery of the metal-rich fluids of the Salton Sea geothermal system and subsequently by the recognition of sulfide-depositing hydrothermal systems on the sea floor. His studies of active hot-spring systems elucidated the principles of geyser activity and provided the scientific foundation for research programs aimed at the understanding of geothermal systems throughout the world.
Geothermal reservoir characterization using distributed temperature sensing at Brady Geothermal Field, Nevada

DOE PAGES

Patterson, Jeremy R.; Cardiff, Michael; Coleman, Thomas; ...

2017-12-01

Distributed temperature sensing (DTS) systems provide near real-time data collection that captures borehole spatiotemporal temperature dynamics. For this study, temperature data was collected in an observation well at an active geothermal site for a period of eight days under geothermal production conditions. Collected temperature data showcase the ability of DTS systems to detect changes to the location of the steam-water interface, visualize borehole temperature recovery — following injection of a coldwater “slug” — and identify anomalously warm and/or cool zones. The high sampling rate and spatial resolution of DTS data also shows borehole temperature dynamics that are not captured bymore » traditional pressure-temperature survey tools. Inversion of thermal recovery data using a finite-difference heat-transfer model produces a thermal-diffusivity profile that is consistent with laboratorymeasured values and correlates with identified lithologic changes within the borehole. Used alone or in conjunction with complementary data sets, DTS systems are useful tools for developing a better understanding of both reservoir rock thermal properties as well as within and near borehole fluid movement.« less
Study of the potential health and environmental impacts from the development of liquid-dominated geothermal resources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, J.M.

1982-09-01

This document describes seven programs to provide scientific input, understanding, and forecasting capability for hydrothermal energy areas needing resolution. The three major areas addressed are (1) the impacts on living components of the aqueous and terrestrial ecosystems, (2) the impacts on the quality of the abiotic environment itself, and (3) the techniques needed to measure releases from hydrothermal activities.
Low-Temperature Projects of the Department of Energy's Geothermal Technologies Program: Evaluation and Lessons Learned

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Tom; Snyder, Neil; Gosnold, Will

This paper discusses opportunities and challenges related to the technical and economic feasibility of developing power generation from geothermal resources at temperatures of 150 degrees C and lower. Insights from projects funded by the U.S. Department of Energy (DOE), Geothermal Technologies Office inform these discussions and provide the basis for some lessons learned to help guide decisions by DOE and the industry in further developing this resource. The technical basis for low-temperature geothermal energy is well established and the systems can be economic today in certain situations. However, these applications are far from a 'plug and play' product; successful developmentmore » today requires a good knowledge of geothermal system design and operation.« less
Geothermal and volcanism in west Java

NASA Astrophysics Data System (ADS)

Setiawan, I.; Indarto, S.; Sudarsono; Fauzi I, A.; Yuliyanti, A.; Lintjewas, L.; Alkausar, A.; Jakah

2018-02-01

Indonesian active volcanoes extend from Sumatra, Jawa, Bali, Lombok, Flores, North Sulawesi, and Halmahera. The volcanic arc hosts 276 volcanoes with 29 GWe of geothermal resources. Considering a wide distribution of geothermal potency, geothermal research is very important to be carried out especially to tackle high energy demand in Indonesia as an alternative energy sources aside from fossil fuel. Geothermal potency associated with volcanoes-hosted in West Java can be found in the West Java segment of Sunda Arc that is parallel with the subduction. The subduction of Indo-Australian oceanic plate beneath the Eurasian continental plate results in various volcanic products in a wide range of geochemical and mineralogical characteristics. The geochemical and mineralogical characteristics of volcanic and magmatic rocks associated with geothermal systems are ill-defined. Comprehensive study of geochemical signatures, mineralogical properties, and isotopes analysis might lead to the understanding of how large geothermal fields are found in West Java compared to ones in Central and East Java. The result can also provoke some valuable impacts on Java tectonic evolution and can suggest the key information for geothermal exploration enhancement.
Behavior of Rare Earth Element In Geothermal Systems; A New Exploration/Exploitation Tool

DOE Office of Scientific and Technical Information (OSTI.GOV)

Scott A. Wood

2002-01-28

The goal of this four-year project was to provide a database by which to judge the utility of the rare earth elements (REE) in the exploration for and exploitation of geothermal fields in the United States. Geothermal fluids from hot springs and wells have been sampled from a number of locations, including: (1) the North Island of New Zealand (1 set of samples); (2) the Cascades of Oregon; (3) the Harney, Alvord Desert and Owyhee geothermal areas of Oregon; (4) the Dixie Valley and Beowawe fields in Nevada; (5) Palinpion, the Philippines: (6) the Salton Sea and Heber geothermal fieldsmore » of southern California; and (7) the Dieng field in Central Java, Indonesia. We have analyzed the samples from all fields for REE except the last two.« less
Geothermal Energy Retrofit

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bachman, Gary

The Cleary University Geothermal Energy Retrofit project involved: 1. A thermal conductivity test; 2. Assessment of alternative horizontal and vertical ground heat exchanger options; 3. System design; 4. Asphalt was stripped from adjacent parking areas and a vertical geothermal ground heat exchanger system installed; 5. the ground heat exchanger was connected to building; 6. a system including 18 heat pumps, control systems, a manifold and pumps, piping for fluid transfer and ductwork for conditioned air were installed throughout the building.
Multiple source components in gas manifestations from north-central Italy

USGS Publications Warehouse

Minissale, A.; Evans, William C.; Magro, G.; Vaselli, O.

1997-01-01

Gas manifestations in north-central Italy consist of CO2-rich gases with minor N2-rich emissions and discharge either along with thermal springs or into cold and stagnant waters. 'Cold' gases are prevalently CO2-dominated (> 90%) while gases related to the thermal waters have variable composition: from CO2 > 99.5% to N2 > 90%. The variable composition of 'thermal' gases is caused by differences in the thermal regime and lithology of the ascent paths, where there is mixing of gases from multiple sources, such as N2-rich atmospheric and deep CO2-rich metamorphic end-members. Elevated concentrations of CH4 and H2 in these gases are generally related to the presence of active geothermal systems at shallow depth, such as the Larderello-Travale field in Tuscany. The ??13C values between coexisting CH4 and CO2 in all samples analyzed suggest that CH4 originates abiogenically in 200-400??C hydrothermal systems. Far from geothermal areas, where the thermal gradient is lower or the water/gas ratio is high because of large inflow of meteoric waters, H2 and CH4 are usually lower. In some cases, they can be scrubbed or oxidized (especially H2), while the residual rising gas becomes indirectly enriched in N2 and CO2. Carbon dioxide is also enriched in some discharged gases because it is produced at shallow depth in lower temperature conditions (< 150??C). Heavy ??15N values for N2 to near +7.0??? suggest that, for some gas samples that contain excess nitrogen (e.g. where N2/Ar ??? 83), this component probably derives from ammonia-rich feldspars and micas within the Palaeozoic schist basement rocks. However, other samples show evidence of a shallow component of CH4 and N2 from Neogene basin sediments. The areal distribution of the 3He/4He ratio points to a general prevalence of atmospheric and crustal 4He in the gas discharges in central Italy. A significant component of mantle 3He is only found in the geothermal areas of Larderello where the large regional thermal anomaly suggests the presence of a deep magmatic body. ?? 1997 Elsevier Science B.V.
Hybridizing a Geothermal Plant with Solar and Thermal Energy Storage to Enhance Power Generation

DOE Office of Scientific and Technical Information (OSTI.GOV)

McTigue, Joshua Dominic P; Zhu, Guangdong; Turchi, Craig S

The objective of this project is to identify cost-effective thermal storage systems for a geothermal/solar hybrid system in order to increase the plant dispatchability. Furthermore, an optimal quantity of thermal storage will also be determined to achieve the best economics of a geothermal/solar hybrid plant. NREL is working with Hyperlight Energy and Coso Operating Company to develop techno-economic models of such a system.
Modeling thermal stress propagation during hydraulic stimulation of geothermal wells

NASA Astrophysics Data System (ADS)

Jansen, Gunnar; Miller, Stephen A.

2017-04-01

A large fraction of the world's water and energy resources are located in naturally fractured reservoirs within the earth's crust. Depending on the lithology and tectonic history of a formation, fracture networks can range from dense and homogeneous highly fractured networks to single large scale fractures dominating the flow behavior. Understanding the dynamics of such reservoirs in terms of flow and transport is crucial to successful application of engineered geothermal systems (also known as enhanced geothermal systems or EGS) for geothermal energy production in the future. Fractured reservoirs are considered to consist of two distinct separate media, namely the fracture and matrix space respectively. Fractures are generally thin, highly conductive containing only small amounts of fluid, whereas the matrix rock provides high fluid storage but typically has much smaller permeability. Simulation of flow and transport through fractured porous media is challenging due to the high permeability contrast between the fractures and the surrounding rock matrix. However, accurate and efficient simulation of flow through a fracture network is crucial in order to understand, optimize and engineer reservoirs. It has been a research topic for several decades and is still under active research. Accurate fluid flow simulations through field-scale fractured reservoirs are still limited by the power of current computer processing units (CPU). We present an efficient implementation of the embedded discrete fracture model, which is a promising new technique in modeling the behavior of enhanced geothermal systems. An efficient coupling strategy is determined for numerical performance of the model. We provide new insight into the coupled modeling of fluid flow, heat transport of engineered geothermal reservoirs with focus on the thermal stress changes during the stimulation process. We further investigate the interplay of thermal and poro-elastic stress changes in the reservoir. Combined with a analytical formulation for the injection temperatures in the open hole section of a geothermal well, the stress changes induced during the injection period of reservoir development can be studied.
Geothermal energy program overview

NASA Astrophysics Data System (ADS)

1991-12-01

The mission of the Geothermal Energy Program is to develop the science and technology necessary for tapping our nation's tremendous heat energy sources contained within the Earth. Geothermal energy is a domestic energy source that can produce clean, reliable, cost-effective heat and electricity for our nation's energy needs. Geothermal energy - the heat of the Earth - is one of our nation's most abundant energy resources. In fact, geothermal energy represents nearly 40 percent of the total U.S. energy resource base and already provides an important contribution to our nation's energy needs. Geothermal energy systems can provide clean, reliable, cost-effective energy for our nation's industries, businesses, and homes in the form of heat and electricity. The U.S. Department of Energy's (DOE) Geothermal Energy Program sponsors research aimed at developing the science and technology necessary for utilizing this resource more fully. Geothermal energy originates from the Earth's interior. The hottest fluids and rocks at accessible depths are associated with recent volcanic activity in the western states. In some places, heat comes to the surface as natural hot water or steam, which have been used since prehistoric times for cooking and bathing. Today, wells convey the heat from deep in the Earth to electric generators, factories, farms, and homes. The competitiveness of power generation with lower quality hydrothermal fluids, geopressured brines, hot dry rock, and magma (the four types of geothermal energy), still depends on the technical advancements sought by DOE's Geothermal Energy Program.
Gas geochemistry and preliminary CO2 output estimation from the island of Kos (Greece)

NASA Astrophysics Data System (ADS)

D'Alessandro, Walter; Daskalopoulou, Kyriaki; Calabrese, Sergio; Longo, Manfredi; Kyriakopoulos, Konstantinos; Gagliano, Antonina Lisa

2017-04-01

Several gas samples have been collected from natural gas manifestations at the island of Kos. Most of them are found underwater along the southern coast of the island. On land two anomalous degassing areas have been recognized. These are characterised by lack of vegetation and after long dry periods by the presence of sulfate salts efflorescences. Almost all the gases are CO2-dominated (CO2 ranging from 88 to 99%) with minor amounts of N2 (up to 7%) and CH4 (up to 2.6%). Only the on-land manifestations have also significant contents of H2 (up to 0.2%) and H2S (up to 0.3%). Only one underwater manifestation is N2-dominated (61-99%) with CH4 (0.6-11%) and low CO2 (0.1-26%). The isotopic composition of He shows values ranging from 0.84 to 6.72 R/RA indicating a sometimes strong mantle contribution with the highest values measured in two of the most strongly degassing areas (Paradise Beach and Volcania). C-isotopic composition of CO2 is in the range from -3.6 to 0.6 ‰ vs V-PDB with most of the values around -1‰ indicating a mixed mantle - limestones origin. Isotopic composition of CH4, ranging from -21.5 to 2.8‰ for C and from -143 to 36‰ for H, points to a geothermal origin with sometimes evident secondary oxidation processes. CO2-flux measurements showed values up to about 10,000 g/m2/day in the areas of Volcania and Kokkino Nero and up to about 50,000 g/m2/day at Paradise beach. Preliminary CO2 output estimations gave values of 8.8 and 4 tons/day for the first two areas respectively and of 2.7 tons/day for the latter. The total output of the island (15.5 tons/day) should be considered a minimum estimation because of the incomplete coverage of the area and is comparable to the other active volcanic/geothermal systems of Greece (Nisyros, Nea Kameni and Methana).
Goechemical and Hydrogeochemical Properties of Cappadocia Geothermal Province

NASA Astrophysics Data System (ADS)

Furkan Sener, Mehmet; Sener, Mehmet; Uysal, Tonguc

2016-04-01

In order to determine the geothermal resource potential of Niǧde, Nevşehir and Aksaray provinces in Central Anatolian Volcanic Province (CAVP), geothermal fluids, surface water, and alteration rock samples from the Cappadocia volcanic zone in Turkey were investigated for their geochemical and stable isotopic characteristics in light of published geological and tectonic studies. Accordingly, the Cappadocia Geothermal Province (CGP) has two different geothermal systems located along tectonic zones including five active and two potential geothermal fields, which are located between Tuzgölü Fault Zone and Keçiboyduran-Melendiz Fault and north of Keçiboyduran-Melendiz Fault. Based on water chemistry and isotope compositions, samples from the first area are characterized by Ca-Mg-HCO3 ve Ca-HCO3 type mineral poor waters and Ca-Na-SO4 and Ca-Mg-SO4 type for the cold waters and the hot waters, respectively, whereas hot waters from the second area are Na-Cl-HCO3 and Ca-Na-HCO3 type mineral poor waters. According to δ18O and δ2H isotope studies, the geothermal waters are fed from meteoric waters. Results of silica geothermometer indicate that the reservoir temperature of Dertalan, Melendiz Mount, Keçiboyduran Mount, Hasan Mount (Keçikalesi), Ziga, Acıgöl, and Derinkuyu geothermal waters are 150-173 oC, 88-117 oC, 91-120 oC, 94-122 oC, 131-156 oC, 157-179 oC; 152-174 oC and 102-130 oC, respectively. The REE composition of geothermal fluids, surface water, and mineral precipitates indicate that temperature has a strong effect on REE fractionation of the sampled fluids. Eu- and Ce- anomalies (Eu/Eu*, Ce/Ce*) are visible in several samples, which are related to the inheritance from the host reservoir rocks and redox-controlled fractionation of these elements during water-rock interactions. REE and Yttrium geochemistry results of altered rock samples and water samples, which were taken from same locations exhibited quite similar features in each system. Hence, it was conclude that the same hydrothermal fluid in geothermal system was reached to the surface and interacted with the surface rocks. Our conceptual geothermal model for Cappadocia Geothermal Province based on our geochemical and hydrogeochemical data in combination with geological and geophysical information suggest that the geothermal resources in this region are controlled by primary (active fault) and secondary (buried fault) tectonic belts. Further, our geochemical data indicate the Paleozoic-Mesozoic marble and gneiss being the reservoir rocks. Geogradient and impending heat fluxes to the surface with a possible crustal thinning, which was developed after regional tectonic activities during the Late Pliocene-Quaternary period, constitutes the heat sources. In addition, our study suggest that the Quaternary tuff and ignimbrites of Cappadocia Volcanics represent the seal rock of the geothermal system. In conclusion this study provide evidence for a significant geothermal potential in the Cappadocia region with well-defined seal rocks. However, further studies are needed to resolve the geothermal fluid source problem. Keywords: Cappadocia, geothermal systems, geochemistry, rare earth elements, hydrogeochemistry, hydrothermal alteration.
Research | NREL

Science.gov Websites

manufacturing, buildings efficiency, concentrating solar power, geothermal energy, transportation, water power Integration Facility Geothermal Energy Grid Modernization Hydrogen & Fuel Cells Integrated Energy Research Research Researching energy systems and technologies-and the science behind them-for a
Protocol for Addressing Induced Seismicity Associated with Enhanced Geothermal Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Majer, Ernie; Nelson, James; Robertson-Tait, Ann

2012-01-01

This Protocol is a living guidance document for geothermal developers, public officials, regulators and the general public that provides a set of general guidelines detailing useful steps to evaluate and manage the effects of induced seismicity related to EGS projects.
Realizing the geothermal electricity potential—water use and consequences

NASA Astrophysics Data System (ADS)

Shankar Mishra, Gouri; Glassley, William E.; Yeh, Sonia

2011-07-01

Electricity from geothermal resources has the potential to supply a significant portion of US baseload electricity. We estimate the water requirements of geothermal electricity and the impact of potential scaling up of such electricity on water demand in various western states with rich geothermal resources but stressed water resources. Freshwater, degraded water, and geothermal fluid requirements are estimated explicitly. In general, geothermal electricity has higher water intensity (l kWh - 1) than thermoelectric or solar thermal electricity. Water intensity decreases with increase in resource enthalpy, and freshwater gets substituted by degraded water at higher resource temperatures. Electricity from enhanced geothermal systems (EGS) could displace 8-100% of thermoelectricity generated in most western states. Such displacement would increase stress on water resources if re-circulating evaporative cooling, the dominant cooling system in the thermoelectric sector, is adopted. Adoption of dry cooling, which accounts for 78% of geothermal capacity today, will limit changes in state-wide freshwater abstraction, but increase degraded water requirements. We suggest a research and development focus to develop advanced energy conversion and cooling technologies that reduce water use without imposing energy and consequent financial penalties. Policies should incentivize the development of higher enthalpy resources, and support identification of non-traditional degraded water sources and optimized siting of geothermal plants.
Thermally conductive cementitious grout for geothermal heat pump systems

DOEpatents

Allan, Marita

2001-01-01

A thermally conductive cement-sand grout for use with a geothermal heat pump system. The cement sand grout contains cement, silica sand, a superplasticizer, water and optionally bentonite. The present invention also includes a method of filling boreholes used for geothermal heat pump systems with the thermally conductive cement-sand grout. The cement-sand grout has improved thermal conductivity over neat cement and bentonite grouts, which allows shallower bore holes to be used to provide an equivalent heat transfer capacity. In addition, the cement-sand grouts of the present invention also provide improved bond strengths and decreased permeabilities. The cement-sand grouts can also contain blast furnace slag, fly ash, a thermoplastic air entraining agent, latex, a shrinkage reducing admixture, calcium oxide and combinations thereof.
Pyramid Lake Renewable Energy Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

John Jackson

2008-03-14

The Pyramid Lake Paiute Tribe is a federally recognized Tribe residing on the Pyramid Lake Reservation in western Nevada. The funding for this project was used to identify blind geothermal systems disconnected from geothermal sacred sites and develop a Tribal energy corporation for evaluating potential economic development for profit.
The YNP Metagenome Project: Environmental Parameters Responsible for Microbial Distribution in the Yellowstone Geothermal Ecosystem

PubMed Central

Inskeep, William P.; Jay, Zackary J.; Tringe, Susannah G.; Herrgård, Markus J.; Rusch, Douglas B.

2013-01-01

The Yellowstone geothermal complex contains over 10,000 diverse geothermal features that host numerous phylogenetically deeply rooted and poorly understood archaea, bacteria, and viruses. Microbial communities in high-temperature environments are generally less diverse than soil, marine, sediment, or lake habitats and therefore offer a tremendous opportunity for studying the structure and function of different model microbial communities using environmental metagenomics. One of the broader goals of this study was to establish linkages among microbial distribution, metabolic potential, and environmental variables. Twenty geochemically distinct geothermal ecosystems representing a broad spectrum of Yellowstone hot-spring environments were used for metagenomic and geochemical analysis and included approximately equal numbers of: (1) phototrophic mats, (2) “filamentous streamer” communities, and (3) archaeal-dominated sediments. The metagenomes were analyzed using a suite of complementary and integrative bioinformatic tools, including phylogenetic and functional analysis of both individual sequence reads and assemblies of predominant phylotypes. This volume identifies major environmental determinants of a large number of thermophilic microbial lineages, many of which have not been fully described in the literature nor previously cultivated to enable functional and genomic analyses. Moreover, protein family abundance comparisons and in-depth analyses of specific genes and metabolic pathways relevant to these hot-spring environments reveal hallmark signatures of metabolic capabilities that parallel the distribution of phylotypes across specific types of geochemical environments. PMID:23653623
Preliminary assessment of the velocity pump reaction turbine as a geothermal total-flow expander

NASA Astrophysics Data System (ADS)

Demuth, O. J.

1984-06-01

The velocity pump reaction turbine (VPRT) was evaluated as a total flow expander in a geothermal-electric conversion cycle. Values of geofluid effectiveness of VPRT systems were estimated for conditions consisting of: a 360(F) geothermal resource, 60 F wet-bulb ambient temperature, zero and 0.003 mass concentrations of dissolved noncondensible gas in the geofluid, 100 and 120 F condensing temperatures, and engine efficiencies ranging from 0.4 to 1.0. Achievable engine efficiencies were estimated to range from 0.77, with plant geofluid effectiveness values ranging as high as 9.5 watt hr-lbm geofluid for the 360 F resource temperature. This value is competitive with magnitudes of geofluid effectiveness projected for advanced binary plants, and is on the order of 40% higher than estimates for dual-flash steam and other total flow systems reviewed. Because of its potentially high performance and relative simplicity, the VPRT system appears to warrant further investigation toward its use in a well-head geothermal plant.

Diversity of sulfate-reducing bacteria in a plant using deep geothermal energy

NASA Astrophysics Data System (ADS)

Alawi, Mashal; Lerm, Stephanie; Vetter, Alexandra; Wolfgramm, Markus; Seibt, Andrea; Würdemann, Hilke

2011-06-01

Enhanced process understanding of engineered geothermal systems is a prerequisite to optimize plant reliability and economy. We investigated microbial, geochemical and mineralogical aspects of a geothermal groundwater system located in the Molasse Basin by fluid analysis. Fluids are characterized by temperatures ranging from 61°C to 103°C, salinities from 600 to 900 mg/l and a dissolved organic carbon content (DOC) between 6.4 to 19.3 mg C/l. The microbial population of fluid samples was analyzed by genetic fingerprinting techniques based on PCR-amplified 16S rRNA- and dissimilatory sulfite reductase genes. Despite of the high temperatures, microbes were detected in all investigated fluids. Fingerprinting and DNA sequencing enabled a correlation to metabolic classes and biogeochemical processes. The analysis revealed a broad diversity of sulfate-reducing bacteria. Overall, the detection of microbes known to be involved in biocorrosion and mineral precipitation indicates that microorganisms could play an important role for the understanding of processes in engineered geothermal systems.
The effect of geothermal fluid composition in lime-pozzolan reactions on elastic and transport properties.

NASA Astrophysics Data System (ADS)

MacFarlane, J.; Vanorio, T.

2016-12-01

Calcium-Silicate-Hydrates (C-S-H) are a complex family of hydrates known to form within hyper-alkaline geothermal systems as well as concrete. Within both environments the formation of C-S-H can be linked to the lime-pozzolan reaction. Pozzolan's defined as a siliceous or alumino-siliceous material, which in itself possesses little or no cementing property, but in the presence of moisture chemically reacts with calcium hydroxide at ordinary temperatures to form cementitious compounds. C-S-H fibers have been discovered in a low permeability, caprock layer beneath the Campi Flegrei caldera, as well as within ancient Roman concrete made using volcanic ash and fluids from the Campi Flegrei region over 2000 years ago. By replicating the recipe for Roman concrete, fibrous minerals have been formed in laboratory experiments and imaged using a scanning electron microscope. The formation of C-S-H within concrete has been shown to depend on the mineral ions present, among other factors. Here, we report on how the geothermal fluid composition effects the elastic and transport properties of laboratory samples. Samples were made using the same volcanic ash as the Romans, called Pozzolana, slaked lime and geothermal fluid. Two geothermal fluids from the Campi Flegrei region were compared, as well as deionized water as a control. Preliminary results have shown changes in both the elastic and transport properties between sample sets made with geothermal fluid and the control. These changes are attributed to the structure of the C-S-H that forms in the lime-pozzolan reaction. Understanding how the geothermal fluid composition controls the properties of this reaction has implications for the understanding of both geothermal systems and concrete engineering.
Groundwater Monitoring and Engineered Geothermal Systems: The Newberry EGS Demonstration

NASA Astrophysics Data System (ADS)

Grasso, K.; Cladouhos, T. T.; Garrison, G.

2013-12-01

Engineered Geothermal Systems (EGS) represent the next generation of geothermal energy development. Stimulation of multiple zones within a single geothermal reservoir could significantly reduce the cost of geothermal energy production. Newberry Volcano in central Oregon represents an ideal location for EGS research and development. As such, the goals of the Newberry EGS Demonstration, operated by AltaRock Energy, Inc., include stimulation of a multiple-zone EGS reservoir, testing of single-well tracers and a demonstration of EGS reservoir viability through flow-back and circulation tests. A shallow, local aquifer supplied the approximately 41,630 m3 (11 million gals) of water used during stimulation of NWG 55-29, a deep geothermal well on the western flank of Newberry Volcano. Protection of the local aquifer is of primary importance to both the Newberry EGS Demonstration and the public. As part of the Demonstration, AltaRock Energy, Inc. has developed and implemented a groundwater monitoring plan to characterize the geochemistry of the local aquifer before, during and after stimulation. Background geochemical conditions were established prior to stimulation of NWG 55-29, which was completed in 2012. Nine sites were chosen for groundwater monitoring. These include the water supply well used during stimulation of NWG 55-29, three monitoring wells, three domestic water wells and two hot seeps located in the Newberry Caldera. Together, these nine monitoring sites represent up-, down- and cross-gradient locations. Groundwater samples are analyzed for 25 chemical constituents, stable isotopes, and geothermal tracers used during stimulation. In addition, water level data is collected at three monitoring sites in order to better characterize the effects of stimulation on the shallow aquifer. To date, no significant geochemical changes and no geothermal tracers have been detected in groundwater samples from these monitoring sites. The Newberry EGS Demonstration groundwater monitoring program is currently on-going.
Multi-Fluid Geothermal Energy Systems: Using CO2 for Dispatchable Renewable Power Generation and Grid Stabilization

NASA Astrophysics Data System (ADS)

Buscheck, T. A.; Bielicki, J. M.; Randolph, J.; Chen, M.; Hao, Y.; Sun, Y.

2013-12-01

Abstract We present an approach to use CO2 to (1) generate dispatchable renewable power that can quickly respond to grid fluctuations and be cost-competitive with natural gas, (2) stabilize the grid by efficiently storing large quantities of energy, (3) enable seasonal storage of solar thermal energy for grid integration, (4) produce brine for power-plant cooling, all which (5) increase CO2 value, rendering CO2 capture to be commerically viable, while (6) sequestering huge quantities of CO2. These attributes reduce carbon intensity of electric power, and enable cost-competitive, dispatchable power from major sources of renewable energy: wind, solar, and geothermal. Conventional geothermal power systems circulate brine as the working fluid to extract heat, but the parasitic power load for this circulation can consume a large portion of gross power output. Recently, CO2 has been considered as a working fluid because its advantageous properties reduce this parasitic loss. We expand on this idea by using multiple working fluids: brine, CO2, and N2. N2 can be separated from air at lower cost than captured CO2, it is not corrosive, and it will not react with the formation. N2 also can improve the economics of energy production and enable energy storage, while reducing operational risk. Extracting heat from geothermal reservoirs often requires submersible pumps to lift brine, but these pumps consume much of the generated electricity. In contrast, our approach drives fluid circulation by injecting supplemental, compressible fluids (CO2, and N2) with high coefficients of thermal expansion. These fluids augment reservoir pressure, produce artesian flow at the producers, and reduce the parasitic load. Pressure augmentation is improved by the thermosiphon effect that results from injecting cold/dense CO2 and N2. These fluids are heated to reservoir temperature, greatly expand, and increase the artesian flow of brine and supplemental fluid at the producers. Rather than using pumps, the thermosiphon directly converts reservoir thermal energy into mechanical energy for fluid circulation. Because stored pressure drives fluid production, the response time is faster than that of conventional geothermal power, already considered to be dispatchable. For conventional geothermal, the parasitic power load is in phase with gross power output. In contrast, our approach can time-shift much of the parasitic power load, which is dominated by the power required to separate N2 from air and compress it for injection. Because N2 is readily available, it can be injected intermittently. Thus, most of the parasitic power load can be shifted to coincide with minimum power demand or when there is a surplus of renewable power. Such a time-shift also allows net power output to be nearly equal to gross power output during peak demand. Energy storage can be almost 100 percent efficient because it is achieved by shifting the parasitic load, which is more efficient than other methods used to store energy and stabilize the grid. This work was performed under the auspices of the U.S. DOE by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.
Vapor condensation onto a non-volatile liquid drop

DOE Office of Scientific and Technical Information (OSTI.GOV)

Inci, Levent; Bowles, Richard K., E-mail: richard.bowles@usask.ca

2013-12-07

Molecular dynamics simulations of miscible and partially miscible binary Lennard–Jones mixtures are used to study the dynamics and thermodynamics of vapor condensation onto a non-volatile liquid drop in the canonical ensemble. When the system volume is large, the driving force for condensation is low and only a submonolayer of the solvent is adsorbed onto the liquid drop. A small degree of mixing of the solvent phase into the core of the particles occurs for the miscible system. At smaller volumes, complete film formation is observed and the dynamics of film growth are dominated by cluster-cluster coalescence. Mixing into the coremore » of the droplet is also observed for partially miscible systems below an onset volume suggesting the presence of a solubility transition. We also develop a non-volatile liquid drop model, based on the capillarity approximations, that exhibits a solubility transition between small and large drops for partially miscible mixtures and has a hysteresis loop similar to the one observed in the deliquescence of small soluble salt particles. The properties of the model are compared to our simulation results and the model is used to study the formulation of classical nucleation theory for systems with low free energy barriers.« less
The furnace in the basement: Part 1, The early days of the Hot Dry Rock Geothermal Energy Program, 1970--1973

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, M.C.

1995-09-01

This report presents the descriptions of the background information and formation of the Los Alamos Scientific Laboratory Geothermal Energy Group. It discusses the organizational, financial, political, public-relations,geologic, hydrologic, physical, and mechanical problems encountered by the group during the period 1970--1973. It reports the failures as well as the successes of this essential first stage in the development of hot dry rock geothermal energy systems.
Numerical Analysis of Combined Well and Open-Closed Loops Geothermal (CWG) Systems

NASA Astrophysics Data System (ADS)

Park, Yu-Chul

2016-04-01

Open-loop geothermal heat pump (GHP) system and closed-loop heat pump systems have been used in Korea to reduce emission of greenhouse gases such as carbon dioxide (CO2). The GHP systems have the pros and cons, for example, the open-loop GHP system is good energy-efficient and the closed-loop GHP system requires minimum maintenance costs. The open-loop GHP system can be used practically only with large amount of groundwater supply. The closed-loop GHP system can be used with high costs of initial installation. The performance and efficiency of the GHP system depend on the characteristics of the GHP system itself in addition to the geologic conditions. To overcome the cons of open-loop or closed-loop GHP system, the combined well and open-closed loops geothermal (CWG) system was designed. The open-loop GHP system is surrounded with closed-loop GHP systems in the CWG system. The geothermal energy in closed-loop GHP systems is supplied by the groundwater pumped by the open-loop GHP system. In this study, 2 different types of the CWG systems (small aperture hybrid CWG system and large aperture CWG system) are estimated using numerical simulation models in the aspect of energy efficiency. This work was supported by the New & Renewable Energy Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea. (No.20153030111120).
The Geysers Geothermal Field Update1990/2010

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brophy, P.; Lippmann, M.; Dobson, P.F.

2010-10-01

In this report, we have presented data in four sections: (1) THE GEYSERS HISTORICAL UPDATE 1990-2010 - A historical update of the primary developments at The Geysers between 1990 and 2010 which uses as its start point Section IIA of the Monograph - 'Historical Setting and History of Development' that included articles by James Koenig and Susan Hodgson. (2) THE GEYSERS COMPREHENSIVE REFERENCE LIST 1990-2010 - In this section we present a rather complete list of technical articles and technical related to The Geysers that were issued during the period 1990-2010. The list was compiled from many sources including, butmore » not limited to scientific journals and conference proceedings. While the list was prepared with care and considerable assistance from many geothermal colleagues, it is very possible that some papers could have been missed and we apologize to their authors in advance. The list was subdivided according to the following topics: (1) Field characterization; (2) Drilling; (3) Field development and management; (4) Induced seismicity; (5) Enhanced Geothermal Systems; (6) Power production and related issues; (7) Environment-related issues; and (8) Other topics. (3) GRC 2010 ANNUAL MEETING GEYSERS PAPERS - Included in this section are the papers presented at the GRC 2010 Annual Meeting that relate to The Geysers. (4) ADDITIONAL GEYSERS PAPERS 1990-2010 - Eighteen additional technical papers were included in this publication in order to give a broad background to the development at The Geysers after 1990. The articles issued during the 1990-2010 period were selected by colleagues considered knowledgeable in their areas of expertise. We forwarded the list of references given in Section 2 to them asking to send us with their selections with a preference, because of limited time, to focus on those papers that would not require lengthy copyright approval. We then chose the articles presented in this section with the purpose of providing the broadest possible view across all technical fields, as related to The Geysers steam-dominated geothermal system. The Geysers has seen many fundamental changes between 1990-2010 and yet the geothermal resource seems still to be robust to the extent that, long after its anticipated life span, we are seeing new geothermal projects being developed on the north and west peripheries of the field. It is hoped that this report provides a focused data source particularly for those just starting their geothermal careers, as well as those who have been involved in the interesting and challenging field of geothermal energy for many years. Despite many hurdles The Geysers has continued to generate electrical power for 50 years and its sustainability has exceeded many early researchers expectations. It also seems probable that, with the new projects described above, generation will continue for many years to come. The success of The Geysers is due to the technical skills and the financial acumen of many people, not only over the period covered by this report (1990-2010), but since the first kilowatt of power was generated in 1960. This Special Report celebrates those 50 years of geothermal development at The Geysers and attempts to document the activities that have brought success to the project so that a permanent record can be maintained. It is strongly hoped and believed that a publication similar to this one will be necessary in another 20 years to document further activities in the field.« less
Association of Cancer Incidence and Duration of Residence in Geothermal Heating Area in Iceland: An Extended Follow-Up

PubMed Central

Kristbjornsdottir, Adalbjorg; Aspelund, Thor; Rafnsson, Vilhjalmur

2016-01-01

Background Residents of geothermal areas have higher incidence of non-Hodgkin’s lymphoma, breast cancer, prostate cancer, and kidney cancers than others. These populations are exposed to chronic low-level ground gas emissions and various pollutants from geothermal water. The aim was to assess whether habitation in geothermal areas and utilisation of geothermal water is associated with risk of cancer according to duration of residence. Methods The cohort obtained from the census 1981 was followed to the end of 2013. Personal identifier was used in record linkage with nation-wide emigration, death, and cancer registries. The exposed population, defined by community codes, was located on young bedrock and had utilised geothermal water supply systems since 1972. Two reference populations were located by community codes on older bedrock or had not utilised geothermal water supply systems for as long a period as had the exposed population. Adjusted hazard ratio (HR), 95% confidence intervals (CI) non-stratified and stratified on cumulative years of residence were estimated in Cox-model. Results The HR for all cancer was 1.21 (95% CI 1.12–1.30) as compared with the first reference area. The HR for pancreatic cancer was 1.93 (1.22–3.06), breast cancer, 1.48 (1.23–1.80), prostate cancer 1.47 (1.22–1.77), kidney cancer 1.46 (1.03–2.05), lymphoid and haematopoietic tissue 1.54 (1.21–1.97), non-Hodgkin´s lymphoma 2.08 (1.38–3.15) and basal cell carcinoma of the skin 1.62 (1.35–1.94). Positive dose-response relationship was observed between incidence of cancers and duration of residence, and between incidence of cancer and degree of geothermal/volcanic activity in the comparison areas. Conclusions The higher cancer incidence in geothermal areas than in reference areas is consistent with previous findings. As the dose-response relationships were positive between incidence of cancers and duration of residence, it is now more urgent than before to investigate the chemical and physical content of the geothermal water and of the ambient air of the areas to detect recognized or new carcinogens. PMID:27205903
ENERGY FROM THE WEST: ENERGY RESOURCE DEVELOPMENT SYSTEMS REPORT. VOLUME VI: GEOTHERMAL

EPA Science Inventory

This report describes the technologies likely to be used for development of geothermal resources in eight western states (Arizona, Colorado, Montana, New Mexico, North Dakota, South Dakota, Utah, and Wyoming). It provides information on input materials and labor requirements, out...
Geothermal Grows Up

ERIC Educational Resources Information Center

Johnson, William C.; Kraemer, Steven; Ormond, Paul

2011-01-01

Self-declared energy and carbon reduction goals on the part of progressive colleges and universities have driven ground source geothermal space heating and cooling systems into rapid evolution, as part of long-term climate action planning efforts. The period of single-building or single-well solutions is quickly being eclipsed by highly engineered…
The Iceland Deep Drilling Project (IDDP): (I) A New Era in Geothermal Development?

NASA Astrophysics Data System (ADS)

Elders, W. A.; Fridleifsson, G. O.; Bird, D. K.; Reed, M. H.; Schiffman, P.; Zierenberg, R.

2007-12-01

The Iceland Deep Drilling Project (IDDP) announced in September 2007 that an international industrial consortium has signed a new contract to collaborate in exploratory deep drilling in Iceland. The main objective of the IDDP is to investigate whether it is economically feasible to produce energy from geothermal systems at supercritical conditions. This will require drilling to depths of 4 to 5 km in order to reach temperatures of 400 to 600°C. Today, geothermal wells in Iceland typically range up to 2.5 km in depth and produce steam at about 300°C, or less, at a rate sufficient to generate about 4 to 7 megawatts of electricity. It is estimated that producing steam from a well penetrating a reservoir with temperatures >450°C, and at a rate of 0.67 cubic meters a second, could generate 40 to 50 MWe. If IDDP's test of this concept proves successful, it could lead to major improvements in the development of high-temperature geothermal resources worldwide. The consortium collaborating to fund this investigation of supercritical geothermal energy consists of three leading Icelandic power companies, Hitaveita Sudurnesja Ltd., Landsvirkjun, Orkuveita Reykjavikur, together with Orkustofnun (the National Energy Authority) and Alcoa Inc. (an international aluminum company). The three power companies financed a feasibility study for the project that was completed in 2003. Each of the three power companies is committed to drill, at their own cost, a 3.5 to 4.0 km deep well in a geothermal field that they operate. The design of these wells will permit them to be deepened to 4.5 or 5.0 km by the IDDP, and funded by the consortium with additional funds from international scientific agencies. The first deep IDDP well will be drilled in the latter part of 2008 in the Krafla geothermal field near the northern end of the central rift zone of Iceland, within a volcanic caldera that has had recent volcanic activity. Two new wells, ~4 km deep, will then be drilled at the Hengill and the Reykjanes geothermal fields during 2009-2010, and subsequently deepened. In contrast to the fresh water systems at Krafla and Hengill, the Reykjanes geothermal system produces hydrothermally modified seawater on the Reykjanes peninsula, in southern Iceland, where the Mid-Atlantic Ridge comes on land in southern Iceland. Processes at depth at Reykjanes should be similar to those responsible for black smokers on ocean spreading centers. The IDDP has engendered considerable international scientific interest. The US National Science Foundation and the International Continental Scientific Drilling Program will jointly fund the coring and sampling for scientific studies. In preparation for studying the data and samples that will be recovered by deep drilling research is underway on samples from existing wells in the target geothermal fields, and on exposed "fossil" geothermal systems and active mid-ocean ridge systems that have conditions believed to be similar to those that will be encountered in deep drilling by the IDDP. Some of these initial scientific studies by US investigators are reported in the accompanying papers.
Use of U and Th Decay-Series Disequilibrium to Characterize Geothermal Systems: An Example from the Coso Geothermal System

NASA Astrophysics Data System (ADS)

Leslie, B. W.; Hammond, D.

2007-12-01

Uranium and thorium decay series isotopes were measured in fluids and solids in the Coso geothermal system to assess the utility and constrain the limitations of the radioisotopic approach to the investigation of rock-water interaction. Fluid radioisotope measurements indicate substantial kilometer-scale variability in chemistry. Between 1988 and 1990, radium isotope activity ratios indicate temporal variability, which is exhibited by apparent mixing relationships observed as a function of time for single wells. Activity ratios of Ra-224/Ra-226 and Ra- 228/Ra-226, and the processes that contribute and remove these radionuclide to and from the fluids, constrain residence times of fluids and may help constrain fluid velocities in the geothermal system. Activity ratios of Ra- 224/Ra-226 > ten were measured. In groundwater and geothermal systems ratios of Ra-224/Ra-226 > ten are limited to zones of thermal upwelling or very young (days to weeks) waters in mountainous areas. Rn-222 results indicate that radon is also an effective tracer for steam velocities within the geothermal system. Analysis of carbon dioxide and Rn-222 data indicates that the residence time of steam (time since separation from the liquid) is short (probably less than four days). Estimates of fluid velocities derived from Rn-222 and radium isotopic measurements are within an order of magnitude of velocities derived from a fluorescein tracer test. Both Rn-222 and Ra-224 activities are higher in single-phase fluids in the northwest as compared to the southeast, indicating a higher rock-surface-area/water-volume ratio in the northwest. Thus, measurements of short-lived radioisotopes and gaseous phase constituents can constrain processes and characteristics of geothermal systems that are usually difficult to constrain (e.g., surface area/volume, residence times). The NRC staff views expressed herein are preliminary and do not constitute a final judgment or determination of the matters addressed or of the acceptability of a license application for a geologic repository at Yucca Mountain.
Chemical reaction path modeling of hydrothermal processes on Mars: Preliminary results

NASA Technical Reports Server (NTRS)

Plumlee, Geoffrey S.; Ridley, W. Ian

1992-01-01

Hydrothermal processes are thought to have had significant roles in the development of surficial mineralogies and morphological features on Mars. For example, a significant proportion of the Martian soil could consist of the erosional products of hydrothermally altered impact melt sheets. In this model, impact-driven, vapor-dominated hydrothermal systems hydrothermally altered the surrounding rocks and transported volatiles such as S and Cl to the surface. Further support for impact-driven hydrothermal alteration on Mars was provided by studies of the Ries crater, Germany, where suevite deposits were extensively altered to montmorillonite clays by inferred low-temperature (100-130 C) hydrothermal fluids. It was also suggested that surface outflow from both impact-driven and volcano-driven hydrothermal systems could generate the valley networks, thereby eliminating the need for an early warm wet climate. We use computer-driven chemical reaction path calculation to model chemical processes which were likely associated with postulated Martian hydrothermal systems.
Bacterial and archaeal diversity in two hot spring microbial mats from the geothermal region of Tengchong, China.

PubMed

Pagaling, Eulyn; Grant, William D; Cowan, Don A; Jones, Brian E; Ma, Yanhe; Ventosa, Antonio; Heaphy, Shaun

2012-07-01

We investigated the bacterial and archaeal diversity in two hot spring microbial mats from the geothermal region of Tengchong in the Yunnan Province, China, using direct molecular analyses. The Langpu (LP) laminated mat was found by the side of a boiling pool with temperature of 60-65 °C and a pH of 8.5, while the Tengchong (TC) streamer mat consisted of white streamers in a slightly acidic (pH 6.5) hot pool outflow with a temperature of 72 °C. Four 16S rRNA gene clone libraries were constructed and restriction enzyme analysis of the inserts was used to identify unique sequences and clone frequencies. From almost 200 clones screened, 55 unique sequences were retrieved. Phylogenetic analysis showed that the LP mat consisted of a diverse bacterial population [Cyanobacteria, Chloroflexi, Chlorobia, Nitrospirae, 'Deinococcus-Thermus', Proteobacteria (alpha, beta and delta subdivisions), Firmicutes, Bacteroidetes and Actinobacteria], while the archaeal population was dominated by methanogenic Euryarchaeota and Crenarchaeota. In contrast, the TC streamer mat consisted of a bacterial population dominated by Aquificae, while the archaeal population also contained Korarchaeota as well as Crenarchaeota and methanogenic Euryarchaeota. These mats harboured clone sequences affiliated to unidentified lineages, suggesting that they are a potential source for discovering novel bacteria and archaea.
Geophysics of Geothermal Areas: State of the Art and Future Development

NASA Astrophysics Data System (ADS)

Mabey, Don R.

In May 1980 a workshop organized by the Advanced School of Geophysics of the Ettore Majorana Center for Scientific Culture was held in Erice, Italy. The purpose was to present the state of the art and future development of geophysics as related to exploration for geothermal resources and the environmental impact of the development of geothermal systems. The workshop was addressed to “younger researchers working in scientific institutions and in public or private agencies and who are particularly interested in these aspects of the energy problem.” Fourteen formal lectures were presented to the workshop. This volume contains papers based on 10 of these lectures with a preface, forward, and introduction by the editors. The ten papers are “Heat Transfer in Geothermal Areas,” “Interpretation of Conductive Heat Flow Anomalies,” “Deep Electromagnetic Soundings in Geothermal Exploration,” “A Computation Method for dc Geoelectric Fields,” “Measurement of Ground Deformation in Geothermal Areas,” “Active Seismic Methods in Geothermal Exploration,” “The Role of Geophysical Investigations in the Discovery of the Latera Geothermal Field,” “Geothermal Resources Exploration in the European Community: The Geophysical Case,” “Activity Performed by AGIP (ENI Group) in the Field of Geothermal Energy,” and “Geothermal Exploration in the Western United States.” Six of the authors are from Italy, and one each is from Iceland, the Netherlands, West Germany, and the United States. All of the papers are in English.
Update on Geothermal Direct-Use Installations in the United States

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beckers, Koenraad J; Young, Katherine R; Snyder, Diana M.

Direct-use of geothermal energy currently has limited penetration in the United States, with an estimated installed capacity of about 500 MWth, supplying on the order of 0.01% of the total annual U.S. heat demand (about 30 EJ). We see higher penetration levels in other countries such as Iceland (about 90%) and Hungary (2.5%). An updated database of geothermal direct-use systems in the U.S. has been compiled and analyzed, building upon the Oregon Institute of Technology (OIT) Geo-Heat Center direct-use database. Types of directuse applications examined include hot springs resorts and pools, aquaculture farms, greenhouses, and district heating systems, among others;more » power-generating facilities and ground-source heat pumps were excluded. Where possible, the current operation status, open and close dates, well data, and other technical data were obtained for each entry. The database contains 545 installations, of which 407 are open, 108 are closed, and 30 have an unknown status. Spas are the most common type of installation, accounting for 50% of installations by number. Aquaculture installations (46 out of 407 open installations) account for the largest percentage (26%) of installed capacity in operation (129 MWth out of 501 MWth). Historical deployment curves show the installed capacity significantly increased in the 1970s and 1980s mainly due to development of geothermal district heating, aquaculture, and greenhouse systems. Since the 2000s, geothermal direct-use development appears to have slowed, and the number of sites in operation decreased due to closures. Case studies reveal multiple barriers to geothermal direct-use implementation and operation, including 1) existence of an information gap among stakeholders, developers, and the general public, 2) competition from cheap natural gas, and 3) the family-owned, small-scale nature of businesses might result in discontinuation among generations.« less
Design and Implementation of Geothermal Energy Systems at West Chester University

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lewis, James

West Chester University has launched a comprehensive transformation of its campus heating and cooling systems from traditional fossil fuels to geothermal. This change will significantly decrease the institution's carbon footprint and serve as a national model for green campus efforts. The institution has designed a phased series of projects to build a district geo-exchange system with shared well fields, central pumping station and distribution piping to provide the geo-exchange water to campus buildings as their internal building HVAC systems are changed to be able to use the geo-exchange water. This project addresses the US Department of Energy Office of Energymore » Efficiency and Renewable Energy (EERE) goal to invest in clean energy technologies that strengthen the economy, protect the environment, and reduce dependence on foreign oil. In addition, this project advances EERE's efforts to establish geothermal energy as an economically competitive contributor to the US energy supply.« less
Cap rock efficiency of geothermal systems in fold-and-thrust belts: Evidence from paleo-thermal and structural analyses in Rosario de La Frontera geothermal area (NW Argentina)

NASA Astrophysics Data System (ADS)

Maffucci, R.; Corrado, S.; Aldega, L.; Bigi, S.; Chiodi, A.; Di Paolo, L.; Giordano, G.; Invernizzi, C.

2016-12-01

Cap rock characterization of geothermal systems is often neglected despite fracturing may reduce its efficiency and favours fluid migration. We investigated the siliciclastic cap rock of Rosario de La Frontera geothermal system (NW Argentina) in order to assess its quality as a function of fracture patterns and related thermal alteration. Paleothermal investigations (XRD on fine-grained fraction of sediments, organic matter optical analysis and fluid inclusions on veins) and 1D thermal modelling allowed us to distinguish the thermal fingerprint associated to sedimentary burial from that related to fluid migration. The geothermal system is hosted in a Neogene N-S anticline dissected by high angle NNW- and ENE-striking faults. Its cap rock can be grouped into two quality categories: rocks acting as good insulators, deformed by NNW-SSE and E-W shear fractures, NNE-SSW gypsum- and N-S-striking calcite-filled veins that developed during the initial stage of anticline growth. Maximum paleo-temperatures (< 60 °C) were experienced during deposition to folding phases. rocks acting as bad insulators, deformed by NNW-SSE fault planes and NNW- and WNW-striking sets of fractures associated to late transpressive kinematics. Maximum paleo-temperatures higher than about 115 °C are linked to fluid migration from the reservoir to surface (with a reservoir top at maximum depths of 2.5 km) along fault damage zones. This multi-method approach turned out to be particularly useful to trace the main pathways of hot fluids and can be applied in blind geothermal systems where either subsurface data are scarce or surface thermal anomalies are lacking.
DOE-GTO Low Temperture Projects Evaluation and Lessons Learned

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Tom; Snyder, Neil; Gosnold, Will

2017-05-01

This paper discusses opportunities and challenges related to the technical and economic feasibility of developing power generation from geothermal resources at temperatures of 150 degrees C and lower. Insights from projects funded by the U.S. Department of Energy (DOE), Geothermal Technologies Office inform these discussions and provide the basis for some lessons learned to help guide decisions by DOE and the industry in further developing this resource. The technical basis for low-temperature geothermal energy is well established and the systems can be economic today in certain situations. However, these applications are far from a 'plug and play' product; successful developmentmore » today requires a good knowledge of geothermal system design and operation.« less

Billy J. Roberts | NREL

Science.gov Websites

technique Wildlife and energy technology interactions Geothermal technology Education M.S., Certificate in . Estimate of the Geothermal Energy Resource in the Major Sedimentary Basins in the United States. Paper the Systems Modeling & Geospatial Data Science Group in the Strategic Energy Analysis Center
Update on Geothermal Direct-Use Installations in the United States

DOE Data Explorer

Beckers, Koenraad F.; Snyder, Diana M.; Young, Katherine R.

2017-03-02

An updated database of geothermal direct-use systems in the U.S. has been compiled and analyzed, building upon the Oregon Institute of Technology (OIT) Geo-Heat Center direct-use database. Types of direct-use applications examined include hot springs resorts and pools, aquaculture farms, greenhouses, and district heating systems, among others; power-generating facilities and ground-source heat pumps were excluded. Where possible, the current operation status, open and close dates, well data, and other technical data were obtained for each entry. The database contains 545 installations, of which 407 are open, 108 are closed, and 30 have an unknown status. A report is also included which details and analyzes current geothermal direct-use installations and barriers to further implementation.
VOC composition of current motor vehicle fuels and vapors, and collinearity analyses for receptor modeling.

PubMed

Chin, Jo-Yu; Batterman, Stuart A

2012-03-01

The formulation of motor vehicle fuels can alter the magnitude and composition of evaporative and exhaust emissions occurring throughout the fuel cycle. Information regarding the volatile organic compound (VOC) composition of motor fuels other than gasoline is scarce, especially for bioethanol and biodiesel blends. This study examines the liquid and vapor (headspace) composition of four contemporary and commercially available fuels: gasoline (<10% ethanol), E85 (85% ethanol and 15% gasoline), ultra-low sulfur diesel (ULSD), and B20 (20% soy-biodiesel and 80% ULSD). The composition of gasoline and E85 in both neat fuel and headspace vapor was dominated by aromatics and n-heptane. Despite its low gasoline content, E85 vapor contained higher concentrations of several VOCs than those in gasoline vapor, likely due to adjustments in its formulation. Temperature changes produced greater changes in the partial pressures of 17 VOCs in E85 than in gasoline, and large shifts in the VOC composition. B20 and ULSD were dominated by C(9) to C(16)n-alkanes and low levels of the aromatics, and the two fuels had similar headspace vapor composition and concentrations. While the headspace composition predicted using vapor-liquid equilibrium theory was closely correlated to measurements, E85 vapor concentrations were underpredicted. Based on variance decomposition analyses, gasoline and diesel fuels and their vapors VOC were distinct, but B20 and ULSD fuels and vapors were highly collinear. These results can be used to estimate fuel related emissions and exposures, particularly in receptor models that apportion emission sources, and the collinearity analysis suggests that gasoline- and diesel-related emissions can be distinguished. Copyright © 2011 Elsevier Ltd. All rights reserved.
Curie point depth from spectral analysis of aeromagnetic data for geothermal reconnaissance in Afghanistan

NASA Astrophysics Data System (ADS)

Saibi, H.; Aboud, E.; Gottsmann, J.

2015-11-01

The geologic setting of Afghanistan has the potential to contain significant mineral, petroleum and geothermal resources. However, much of the country's potential remains unknown due to limited exploration surveys. Here, we present countrywide aeromagnetic data to estimate the Curie point depth (CPD) and to evaluate the geothermal exploration potential. CPD is an isothermal surface at which magnetic minerals lose their magnetization and as such outlines an isotherm of about 580 °C. We use spectral analysis on the aeromagnetic data to estimate the CPD spatial distribution and compare our findings with known geothermal fields in the western part of Afghanistan. The results outline four regions with geothermal potential: 1) regions of shallow Curie point depths (∼16-21 km) are located in the Helmand basin. 2) regions of intermediate depths (∼21-27 km) are located in the southern Helmand basin and the Baluchistan area. 3) Regions of great depths (∼25-35 km) are located in the Farad block. 4) Regions of greatest depths (∼35-40 km) are located in the western part of the northern Afghanistan platform. The deduced thermal structure in western Afghanistan relates to the collision of the Eurasian and Indian plates, while the shallow CPDs are related to crustal thinning. This study also shows that the geothermal systems are associated with complex magmatic and tectonic association of major intrusions and fault systems. Our results imply geothermal gradients ranging from 14 °C/km to 36 °C/km and heat-flow values ranging from 36 to 90 mW/m2 for the study area.
Publications - GMC 366 | Alaska Division of Geological & Geophysical

Science.gov Websites

Alaska MAPTEACH Tsunami Inundation Mapping Energy Resources Gas Hydrates STATEMAP Program information DGGS GMC 366 Publication Details Title: Makushin Geothermal Project ST-1R Core 2009 re-sampling and analysis: Analytical results for anomalous precious and base metals associated with geothermal systems
GEOTHERMAL ENVIRONMENTAL ASSESSMENT BASELINE STUDY: VEGETATION AND SOILS OF THE ROOSEVELT HOT SPRINGS GEOTHERMAL RESOURCE AREA

EPA Science Inventory

Identification and elemental concentrations of indigenous soil and plant systems found on the Roosevelt Hot Spring KGRA are described. Twenty-three different soils and five separate plant communities are geographically mapped and identified. One hundred forty-seven plant species ...
Fault-controlled permeability and fluid flow in low-porosity crystalline rocks: an example from naturally fractured geothermal systems in the Southern Andes

NASA Astrophysics Data System (ADS)

Arancibia, G.; Roquer, T.; Sepúlveda, J.; Veloso, E. A.; Morata, D.; Rowland, J. V.

2017-12-01

Fault zones can control the location, emplacement, and evolution of economic mineral deposits and geothermal systems by acting as barriers and/or conduits to crustal fluid flow (e.g. magma, gas, oil, hydro-geothermal and groundwater). The nature of the fault control permeability is critical in the case of fluid flow into low porosity/permeability crystalline rocks, since structural permeability provides the main hydraulic conductivity to generate a natural fractured system. However, several processes accompanying the failure of rocks (i.e. episodic permeability given by cycling ruptures, mineral precipitation from fluids in veins, dissolution of minerals in the vicinity of a fracture) promote a complex time-dependent and enhancing/reducing fault-controlled permeability. We propose the Southern Volcanic Zone (Southern Andes, Chile) as a case study to evaluate the role of the structural permeability in low porosity crystalline rocks belonging to the Miocene North Patagonian Batholith. Recently published studies propose a relatively well-constrained first-order role of two active fault systems, the arc-parallel (NS to NNE trending) Liquiñe Ofqui Fault System and the arc-oblique (NW trending) Andean Transverse Fault Zones, in fluid flow at crustal scales. We now propose to examine the Liquiñe ( 39°S) and Maihue ( 40°S) areas as sites of interaction between these fault systems, in order to evaluate a naturally fractured geothermal system. Preliminary results indicate upwelling of thermal water directly from fractured granite or from fluvial deposits overlying granitoids. Measured temperatures of thermal springs suggest a low- to medium-enthalpy system, which could potentially be harnessed for use in geothermal energy applications (e.g. heating, wood dryer and green house), which are much needed in Southern Chile. Future work will aim to examine the nature of structural permeability from the regional to the microscopic scale connecting the paleo- and current- fluid flow through the fractured media. Results will contribute to a better understanding of geothermal systems in the Andean tectonic setting and of naturally fractured reservoirs in low-porosity crystalline rocks around the world. Acknowledgments: This work is funded by CEGA-FONDAP/CONICYT #15090013 and VRI-PUENTE #P1703/2017.
Structural controls of the Tuscarora geothermal field, Elko County, Nevada

NASA Astrophysics Data System (ADS)

Dering, G.; Faulds, J. E.

2012-12-01

Tuscarora is an amagmatic geothermal system located ~90 km northwest of Elko, Nevada, in the northern part of the Basin and Range province ~15 km southeast of the Snake River Plain. Detailed geologic mapping, structural analysis, and well data have been integrated to identify the structural controls of the Tuscarora geothermal system. The structural framework of the geothermal field is defined by NNW- to NNE-striking normal faults that are approximately orthogonal to the present extension direction. Boiling springs, fumaroles, and siliceous sinter emanate from a single NNE-striking, west-dipping normal fault. Normal faults west of these hydrothermal features mostly dip steeply east, whereas normal faults east of the springs primarily dip west. Thus, the springs, fumaroles, and sinter straddle a zone of interaction between fault sets that dip toward each other, classified as a strike-parallel anticlinal accommodation zone. Faults within the geothermal area are mostly discontinuous along strike with offsets of tens to hundreds of meters, whereas the adjacent range-bounding fault systems of the Bull Run and Independence Mountains accommodate several kilometers of displacement. The geothermal field lies within a broad step over between the southward terminating west-dipping Bull Run fault zone and the northward terminating west-dipping Independence Mountains fault zone. Neither of these major fault zones is known to host high temperature geothermal systems. The accommodation zone lies within the broad step over and contains both east-dipping antithetic and west-dipping synthetic faults. Accommodation zones are relatively common structural components of extended terranes that transfer strain between oppositely dipping fault sets via a network of subsidiary normal faults. This study has identified the hinge zone of an anticlinal accommodation zone as the site most conducive to fluid up-flow. The recognition of this specific portion of an accommodation zone as a favorable structural setting for geothermal activity may be a useful exploration tool for development of drilling targets in extensional terranes, as well as for developing geologic models of known geothermal fields. This type of information may ultimately help to reduce the risks of targeting successful geothermal wells in such settings.
Hydrogeochemical characteristics and genesis of the high-temperature geothermal system in the Tashkorgan basin of the Pamir syntax, western China

NASA Astrophysics Data System (ADS)

Li, Yiman; Pang, Zhonghe; Yang, Fengtian; Yuan, Lijuan; Tang, Pinghui

2017-11-01

High-temperature geothermal systems in China, such as those found in Tenchong and Tibet, are common. A similar system without obvious manifestations found in the Tashkorgan basin in the western Xinjiang Autonomous Region, however, was not expected. The results from borehole measurements and predictions with geothermometers, such as quartz, Na-K and Na-K-Mg, indicate that the reservoir temperature is approximately 250-260 °C. Geothermal water is high in Total Dissolved Solids (>2.5 g/L) and SiO2 content (>273 mg/L), and the water type is Cl·SO4-Na, likely resulting from water-rock interactions in the granodiorite reservoirs. Based on isotope analysis, it appears to be recharged by local precipitation and river water. Evidence from the relationships between major ions and the Cl and molar Na/Cl ratio suggests mixing between deep geothermal water and shallow cold groundwater during the upwelling process. Mixing ratios calculated by the relationship between Cl and SiO2 show that the proportion from cold end-members are 96-99% and 40-90% for riparian zone springs and geothermal water from boreholes, respectively. Active regional tectonic and Neo-tectonic movements in the Pamir syntax as well as radioactive elements in the granodiorite reservoir of the Himalayan stage provide basis for the high heat flow background (150-350 mW/m2). NNW trending fault systems intersecting with overlying NE faults provide circulation conduits with high permeability for geothermal water.
Towards understanding the puzzling lack of acid geothermal springs in Tibet (China): Insight from a comparison with Yellowstone (USA) and some active volcanic hydrothermal systems

NASA Astrophysics Data System (ADS)

Guo, Qinghai; Kirk Nordstrom, D.; Blaine McCleskey, R.

2014-11-01

Explanations for the lack of acid geothermal springs in Tibet are inferred from a comprehensive hydrochemical comparison of Tibetan geothermal waters with those discharged from Yellowstone (USA) and two active volcanic areas, Nevado del Ruiz (Colombia) and Miravalles (Costa Rica) where acid springs are widely distributed and diversified in terms of geochemical characteristic and origin. For the hydrothermal areas investigated in this study, there appears to be a relationship between the depths of magma chambers and the occurrence of acid, chloride-rich springs formed via direct magmatic fluid absorption. Nevado del Ruiz and Miravalles with magma at or very close to the surface (less than 1-2 km) exhibit very acidic waters containing HCl and H2SO4. In contrast, the Tibetan hydrothermal systems, represented by Yangbajain, usually have fairly deep-seated magma chambers so that the released acid fluids are much more likely to be fully neutralized during transport to the surface. The absence of steam-heated acid waters in Tibet, however, may be primarily due to the lack of a confining layer (like young impermeable lavas at Yellowstone) to separate geothermal steam from underlying neutral chloride waters and the possible scenario that the deep geothermal fluids below Tibet carry less H2S than those below Yellowstone.
GEOTHERM Data Set

DOE Data Explorer

DeAngelo, Jacob

1983-01-01

GEOTHERM is a comprehensive system of public databases and software used to store, locate, and evaluate information on the geology, geochemistry, and hydrology of geothermal systems. Three main databases address the general characteristics of geothermal wells and fields, and the chemical properties of geothermal fluids; the last database is currently the most active. System tasks are divided into four areas: (1) data acquisition and entry, involving data entry via word processors and magnetic tape; (2) quality assurance, including the criteria and standards handbook and front-end data-screening programs; (3) operation, involving database backups and information extraction; and (4) user assistance, preparation of such items as application programs, and a quarterly newsletter. The principal task of GEOTHERM is to provide information and research support for the conduct of national geothermal-resource assessments. The principal users of GEOTHERM are those involved with the Geothermal Research Program of the U.S. Geological Survey.
Wellbore and groundwater temperature distribution eastern Snake River Plain, Idaho: Implications for groundwater flow and geothermal potential

DOE PAGES

McLing, Travis L.; Smith, Richard P.; Smith, Robert W.; ...

2016-04-10

A map of groundwater temperatures from the Eastern Snake River Plain (ESRP) regional aquifer can be used to identify and interpret important features of the aquifer, including aquifer flow direction, aquifer thickness, and potential geothermal anomalies. The ESRP is an area of high heat flow, yet most of this thermal energy fails to reach the surface, due to the heat being swept downgradient by the aquifer to the major spring complexes near Thousand Springs, ID, a distance of 300 km. Nine deep boreholes that fully penetrate the regional aquifer display three common features: (1) high thermal gradients beneath the aquifer,more » corresponding to high conductive heat flow in low-permeability hydrothermally-altered rocks; (2) isothermal temperature profiles within the aquifer, characteristic of an actively flowing groundwater; and (3) moderate thermal gradients in the vadose zone with values that indicate that over half of the geothermal heat flow is removed by advective transport in the regional aquifer system. This study utilized temperature data from 250 ESRP aquifer wells to evaluate regional aquifer flow direction, aquifer thickness, and potential geothermal anomalies. Because the thermal gradients are typically low in the aquifer, any measurement of groundwater temperature is a reasonable estimate of temperature throughout the aquifer thickness, allowing the construction of a regional aquifer temperature map for the ESRP. Mapped temperatures are used to identify cold thermal plumes associated with recharge from tributary valleys and adjacent uplands, and warm zones associated with geothermal input to the aquifer. Warm zones in the aquifer can have various causes, including local circulation of groundwater through the deep conductively dominated region, slow groundwater movement in low-permeability regions, or localized heat flow from deeper thermal features.« less
Phylogenetic diversity analysis of subterranean hot springs in Iceland.

PubMed

Marteinsson, V T; Hauksdóttir, S; Hobel, C F; Kristmannsdóttir, H; Hreggvidsson, G O; Kristjánsson, J K

2001-09-01

Geothermal energy has been harnessed and used for domestic heating in Iceland. In wells that are typically drilled to a depth of 1,500 to 2,000 m, the temperature of the source water is 50 to 130 degrees C. The bottoms of the boreholes can therefore be regarded as subterranean hot springs and provide a unique opportunity to study the subterranean biosphere. Large volumes of geothermal fluid from five wells and a mixture of geothermal water from 50 geothermal wells (hot tap water) were sampled and concentrated through a 0.2-microm-pore-size filter. Cells were observed in wells RG-39 (91.4 degrees C) and MG-18 (71.8 degrees C) and in hot tap water (76 degrees C), but no cells were detected in wells SN-4, SN-5 (95 to 117 degrees C), and RV-5 (130 degrees C). Archaea and Bacteria were detected by whole-cell fluorescent in situ hybridization. DNAs were extracted from the biomass, and small-subunit rRNA genes (16S rDNAs) were amplified by PCR using primers specific for the Archaea and Bacteria domains. The PCR products were cloned and sequenced. The sequence analysis showed 11 new operational taxonomic units (OTUs) out of 14, 3 of which were affiliated with known surface OTUs. Samples from RG-39 and hot tap water were inoculated into enrichment media and incubated at 65 and 85 degrees C. Growth was observed only in media based on geothermal water. 16S rDNA analysis showed enrichments dominated with Desulfurococcales relatives. Two strains belonging to Desulfurococcus mobilis and to the Thermus/Deinococcus group were isolated from borehole RG-39. The results indicate that subsurface volcanic zones are an environment that provides a rich subsurface for novel thermophiles.
Changes in the water quality and bacterial community composition of an alkaline and saline oxbow lake used for temporary reservoir of geothermal waters.

PubMed

Borsodi, Andrea K; Szirányi, Barbara; Krett, Gergely; Márialigeti, Károly; Janurik, Endre; Pekár, Ferenc

2016-09-01

Geothermal waters exploited in the southeastern region of Hungary are alkali-hydrogen-carbonate type, and beside the high amount of dissolved salt, they contain a variety of aromatic, heteroaromatic, and polyaromatic hydrocarbons. The majority of these geothermal waters used for heating are directed into surface waters following a temporary storage in reservoir lakes. The aim of this study was to gain information about the temporal and spatial changes of the water quality as well as the bacterial community composition of an alkaline and saline oxbow lake operated as reservoir of used geothermal water. On the basis of the water physical and chemical measurements as well as the denaturing gradient gel electrophoresis (DGGE) patterns of the bacterial communities, temporal changes were more pronounced than spatial differences. During the storage periods, the inflow, reservoir water, and sediment samples were characterized with different bacterial community structures in both studied years. The 16S ribosomal RNA (rRNA) gene sequences of the bacterial strains and molecular clones confirmed the differences among the studied habitats. Thermophilic bacteria were most abundant in the geothermal inflow, whereas the water of the reservoir was dominated by cyanobacteria and various anoxygenic phototrophic prokaryotes. In addition, members of several facultative anaerobic denitrifying, obligate anaerobic sulfate-reducing and syntrophic bacterial species capable of decomposition of different organic compounds including phenols were revealed from the water and sediment of the reservoir. Most of these alkaliphilic and/or halophilic species may participate in the local nitrogen and sulfur cycles and contribute to the bloom of phototrophs manifesting in a characteristic pink-reddish discoloration of the water of the reservoir.
Development of Models to Simulate Tracer Tests for Characterization of Enhanced Geothermal Systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Williams, Mark D.; Reimus, Paul; Vermeul, Vincent R.

2013-05-01

A recent report found that power and heat produced from enhanced (or engineered) geothermal systems (EGSs) could have a major impact on the U.S energy production capability while having a minimal impact on the environment. EGS resources differ from high-grade hydrothermal resources in that they lack sufficient temperature distribution, permeability/porosity, fluid saturation, or recharge of reservoir fluids. Therefore, quantitative characterization of temperature distributions and the surface area available for heat transfer in EGS is necessary for the design and commercial development of the geothermal energy of a potential EGS site. The goal of this project is to provide integrated tracermore » and tracer interpretation tools to facilitate this characterization. This project was initially focused on tracer development with the application of perfluorinated tracer (PFT) compounds, non-reactive tracers used in numerous applications from atmospheric transport to underground leak detection, to geothermal systems, and evaluation of encapsulated PFTs that would release tracers at targeted reservoir temperatures. After the 2011 midyear review and subsequent discussions with the U.S. Department of Energy Geothermal Technology Program (GTP), emphasis was shifted to interpretive tool development, testing, and validation. Subsurface modeling capabilities are an important component of this project for both the design of suitable tracers and the interpretation of data from in situ tracer tests, be they single- or multi-well tests. The purpose of this report is to describe the results of the tracer and model development for simulating and conducting tracer tests for characterizing EGS parameters.« less
The use of novel DNA nanotracers to determine groundwater flow paths - a test study at the Grimsel Deep Underground Geothermal (DUG) Laboratory in Switzerland

NASA Astrophysics Data System (ADS)

Kittilä, Anniina; Evans, Keith; Puddu, Michela; Mikutis, Gediminas; Grass, Robert N.; Deuber, Claudia; Saar, Martin O.

2016-04-01

Groundwater flow in fractured media is heterogeneous and takes place in structures with complex geometry and scale effects, which make the characterization and modeling of the groundwater flow technically challenging. Surface geophysical surveys have limited resolution of permeable structures, and often provide ambiguous results, whereas the interpretation of borehole flow logs to infer hydraulic flow paths within fractured reservoirs is usually non-unique. Nonetheless, knowledge of the hydraulic properties of individual fractures and the role they play in determining the larger-scale flow within the fracture network (i.e. the overall flow conditions) is required in many hydrogeological and geo-engineering situations, such as in geothermal reservoir studies. Tracer tests can overcome some of the aforementioned limitations by providing strong constraints on the geometry and characteristics of flow paths linking boreholes within both porous media and fracture-dominated types of reservoirs. In the case of geothermal reservoirs, tracer tests are often used to provide estimates of the pore/fracture volume swept by flow between injection and production wells. This in turn places constraints on the swept surface area, a parameter that is key for estimating the commercial longevity of the geothermal system. A problem with conventional tracer tests is that the solute species used as the tracer tend to persist in detectable quantities within the reservoir for a long time, thereby impeding repeat tracer tests. DNA nanotracers do not suffer from this problem as they can be designed with a unique signature for each test. DNA nanotracers are environmentally friendly, sub-micron sized silica particles encapsulating small fragments of synthetic DNA which can be fabricated to have a specified, uniquely detectable configuration. For this reason, repeat tracer tests conducted with a differently-encoded DNA fragment to that used in the original will not suffer interference from the earlier test. In this study, we present the results of tests of applying novel DNA nanotracers to characterize groundwater flow properties and the flow pathways in a fracture-dominated reservoir in the Deep Underground Geothermal (DUG) Laboratory at the Grimsel Test Site in the Swiss Alps. This study is motivated by subsequent comparisons of similar characterizations of fractured rock masses after hydraulic stimulation. These will take place at the DUG Lab at the end of 2016. The results of the flow-path characterization are also compared with those obtained from classical solute tracer tests.
COTHERM: Geophysical Modeling of High Enthalpy Geothermal Systems

NASA Astrophysics Data System (ADS)

Grab, Melchior; Maurer, Hansruedi; Greenhalgh, Stewart

2014-05-01

In recent years geothermal heating and electricity generation have become an attractive alternative energy resource, especially natural high enthalpy geothermal systems such as in Iceland. However, the financial risk of installing and operating geothermal power plants is still high and more needs to be known about the geothermal processes and state of the reservoir in the subsurface. A powerful tool for probing the underground system structure is provided by geophysical techniques, which are able to detect flow paths and fracture systems without drilling. It has been amply demonstrated that small-scale features can be well imaged at shallow depths, but only gross structures can be delineated for depths of several kilometers, where most high enthalpy systems are located. Therefore a major goal of our study is to improve geophysical mapping strategies by multi-method geophysical simulations and synthetic data inversions, to better resolve structures at greater depth, characterize the reservoir and monitor any changes within it. The investigation forms part of project COTHERM - COmbined hydrological, geochemical and geophysical modeling of geoTHERMal systems - in which a holistic and synergistic approach is being adopted to achieve multidisciplinary cooperation and mutual benefit. The geophysical simulations are being performed in combination with hydrothermal fluid flow modeling and chemical fluid rock interaction modeling, to provide realistic constraints on lithology, pressure, temperature and fluid conditions of the subsurface. Two sites in Iceland have been selected for the study, Krafla and Reykjanes. As a starting point for the geophysical modeling, we seek to establish petrophysical relations, connecting rock properties and reservoir conditions with geophysical parameters such as seismic wave speed, attenuation, electrical conductivity and magnetic susceptibility with a main focus on seismic properties. Therefore, we follow a comprehensive approach involving three components: (1) A literature study to find relevant, existing theoretical models, (2) laboratory determinations to confirm their validity for Icelandic rocks of interest and (3) a field campaign to obtain in-situ, shallow rock properties from seismic and resistivity tomography surveys over a fossilized and exhumed geothermal system. Theoretical models describing physical behavior for rocks with strong inhomogeneities, complex pore structure and complicated fluid-rock interaction mechanisms are often poorly constrained and require the knowledge about a wide range of parameters that are difficult to quantify. Therefore we calibrate the theoretical models by laboratory measurements on samples of rocks, forming magmatic geothermal reservoirs. Since the samples used in the laboratory are limited in size, and laboratory equipment operates at much higher frequency than the instruments used in the field, the results need to be up-scaled from the laboratory scale to field scale. This is not a simple process and entails many uncertainties.
A new illite geothermometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ballantyne, Judith M.; Moore, Joseph N.

1988-01-01

Sericite, either as illite or illite/smectite, is ubiquitous in geothermal systems. Theoretical Ca- and Na-smectite contents of non-expanding geothermal sericites have been calculated from published electron microprobe analyses. Geothermal sericites can be modeled as solid solutions of muscovite and smectite. For those sericites that fit the model, the amount of smectite in solid solution is related to temperature by the expression TºC = 1000/(0.45LogX{sub smectite} + 2.38) – 273. The temperature dependence of illite interlayer chemistry suggests a related temperature dependence of the K, Na and Ca content of geothermal fluids. The original data used by Fournier and Truesdell (1973)more » to derive the empirical Na-K-Ca geothermometer for geothermal fluids can be modeled equally well by an equation incorporating the equilibrium constant for the reaction of smectite to illite: T ºC = 1.145*10{sup 3}/([0.35LogNa + 0.175LogCa – 0.75LogK] + 1.51) – 273, where the concentration units are molalities. This supports the hypothesis that illite and illite/smectite are important controls on the concentrations of Na, K and Ca in geothermal fluids.« less
Oilfield geothermal exploitation in China-A case study from the Liaohe oilfield in Bohai Bay Basin

NASA Astrophysics Data System (ADS)

Wang, Shejiao; Yao, Yanhua; Fan, Xianli; Yan, Jiahong

2017-04-01

The clean geothermal energy can play a huge role in solving the problem of severe smog in China as it can replace large coal-fired heating in winter. Chinese government has paid close attention on the development and utilization of geothermal energy. In the "13th Five-Year" plan, the geothermal development is included into the national plan for the first time. China is very rich in the medium and low-temperature geothermal resources, ranking first in the geothermal direct use in the world for a long time. The geothermal resources are mainly concentrated in sedimentary basins, especially in petroliferous basins distributed in North China (in North China, heating is needed in winter). These basins are usually close to the large- and medium-sized cities. Therefore, tapping oilfield geothermal energy have attracted a great attention in the last few years as the watercut achieved above 90% in most oilfields and significant progress has been made. In this paper, taking the Liaohe Oilfield in the Bohai Bay Basin as an example, we discussed the distribution and potential of the geothermal resources, discussed how to use the existed technology to harness geothermal energy more effectively, and forecasted the development prospect of the oilfield geothermal energy. By using the volumetric method, we calculated the geothermal resources of the Guantao Formation, Dongying Formation, Shahejie Formation and basement rock in the Liaohe depression. We tested the geothermal energy utilization efficiency in different conditions by applying different pump technologies and utilizing geothermal energy in different depth, such as shallow geothermal energy (0-200m), middle-deep depth geothermal energy (200-4000m), and oilfield sewage heat produced with oil production. For the heat pump systems, we tested the conventional heat pump system, high-temperature heat pump system, super high-temperature heat pump system, and gas heat pump system. Finally, based on the analysis of national policy, the heat demands of oilfield, and the exploration and development technologies, we discussed the potential of the oilfield geothermal energy development for the industrial and the civil applications in the future.
Sensitivity of predicted scaling and permeability in Enhanced Geothermal Systems to Thermodynamic Data and Activity Models

NASA Astrophysics Data System (ADS)

Hingerl, Ferdinand F.; Wagner, Thomas; Kulik, Dmitrii A.; Kosakowski, Georg; Driesner, Thomas; Thomsen, Kaj

2010-05-01

A consortium of research groups from ETH Zurich, EPF Lausanne, the Paul Scherrer Institut and the University of Bonn collaborates in a comprehensive program of basic research on key aspects of the Enhanced Geothermal Systems (EGSs). As part of this GEOTHERM project (www.geotherm.ethz.ch), we concentrate on the fundamental investigation of thermodynamic models suitable for describing fluid-rock interactions at geothermal conditions. Predictions of the fluid-rock interaction in EGS still face several major challenges. Slight variations in the input thermodynamic and kinetic parameters may result in significant differences in the predicted mineral solubilities and stable assemblage. Realistic modeling of mineral precipitation in turn has implications onto our understanding of the permeability evolution of the geothermal reservoir, as well as the scaling in technical installations. In order to reasonably model an EGS, thermodynamic databases and activity models must be tailored to geothermal conditions. We therefore implemented in GEMS code the Pitzer formalism, which is the standard model used for computing thermodynamic excess properties of brines at elevated temperatures and pressures. This model, however, depends on a vast amount of interaction parameters, which are to a substantial extend unknown. Furthermore, a high order polynomial temperature interpolation makes extrapolation unreliable if not impossible. As an alternative we additionally implemented the EUNIQUAC activity model. EUNIQUAC requires fewer empirical fit parameters (only binary interaction parameters needed) and uses simpler and more stable temperature and pressure extrapolations. This results in an increase in computation speed, which is of crucial importance when performing coupled long term simulations of geothermal reservoirs. To achieve better performance under geothermal conditions, we are currently partly reformulating EUNIQUAC and refitting the existing parameter set. First results of the Pitzer-EUNIQUAC benchmark applied to relevant aqueous solutions at elevated temperature, pressure and ionic strength will be presented.

iTOUGH2-EOS1SC. Multiphase Reservoir Simulator for Water under Sub- and Supercritical Conditions. User's Guide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Magnusdottir, Lilja; Finsterle, Stefan

2015-03-01

Supercritical fluids exist near magmatic heat sources in geothermal reservoirs, and the high enthalpy fluid is becoming more desirable for energy production with advancing technology. In geothermal modeling, the roots of the geothermal systems are normally avoided but in order to accurately predict the thermal behavior when wells are drilled close to magmatic intrusions, it is necessary to incorporate the heat sources into the modeling scheme. Modeling supercritical conditions poses a variety of challenges due to the large gradients in fluid properties near the critical zone. This work focused on using the iTOUGH2 simulator to model the extreme temperature andmore » pressure conditions in magmatic geothermal systems.« less
Three-dimensional seismic structure and moment tensors of non-double-couple earthquakes at the Hengill-Grensdalur volcanic complex, Iceland

USGS Publications Warehouse

Miller, A.D.; Julian, B.R.; Foulger, G.R.

1998-01-01

The volcanic and geothermal areas of Iceland are rich sources of non-double-couple (non-DC) earthquakes. A state-of-the-art digital seismometer network deployed at the Hengill-Grensdalur volcanic complex in 1991 recorded 4000 small earthquakes. We used the best recorded of these to determine 3-D VP and VP/VS structure tomographically and accurate earthquake moment tensors. The VP field is dominated by high seismic wave speed bodies interpreted as solidified intrusions. A widespread negative (-4 per cent) VP/VS anomaly in the upper 4 km correlates with the geothermal field, but is too strong to be caused solely by the effect of temperature upon liquid water or the presence of vapour, and requires in addition mineralogical or lithological differences between the geothermal reservoir and its surroundings. These may be caused by geothermal alteration. Well-constrained moment tensors were obtained for 70 of the best-recorded events by applying linear programming methods to P- and S-wave polarities and amplitude ratios. About 25 per cent of the mechanisms are, within observational error, consistent with DC mechanisms consistent with shear faulting. The other 75 per cent have significantly non-DC mechanisms. Many have substantial explosive components, one has a substantial implosive component, and the deviatoric component of many is strongly non-DC. Many of the non-DC mechanisms are consistent, within observational error, with simultaneous tensile and shear faulting. However, the mechanisms occupy a continuum in source-type parameter space and probably at least one additional source process is occurring. This may be fluid flow into newly formed cracks, causing partial compensation of the volumetric component. Studying non-shear earthquakes such as these has great potential for improving our understanding of geothermal processes and earthquake source processes in general.
Geotherm: the U.S. geological survey geothermal information system

USGS Publications Warehouse

Bliss, J.D.; Rapport, A.

1983-01-01

GEOTHERM is a comprehensive system of public databases and software used to store, locate, and evaluate information on the geology, geochemistry, and hydrology of geothermal systems. Three main databases address the general characteristics of geothermal wells and fields, and the chemical properties of geothermal fluids; the last database is currently the most active. System tasks are divided into four areas: (1) data acquisition and entry, involving data entry via word processors and magnetic tape; (2) quality assurance, including the criteria and standards handbook and front-end data-screening programs; (3) operation, involving database backups and information extraction; and (4) user assistance, preparation of such items as application programs, and a quarterly newsletter. The principal task of GEOTHERM is to provide information and research support for the conduct of national geothermal-resource assessments. The principal users of GEOTHERM are those involved with the Geothermal Research Program of the U.S. Geological Survey. Information in the system is available to the public on request. ?? 1983.
Thermal properties variations in unconsolidated material for very shallow geothermal application (ITER project)

NASA Astrophysics Data System (ADS)

Sipio, Eloisa Di; Bertermann, David

2018-04-01

In engineering, agricultural and meteorological project design, sediment thermal properties are highly important parameters, and thermal conductivity plays a fundamental role when dimensioning ground heat exchangers, especially in very shallow geothermal systems. Herein, the first 2 m of depth from surface is of critical importance. However, the heat transfer determination in unconsolidated material is difficult to estimate, as it depends on several factors, including particle size, bulk density, water content, mineralogy composition and ground temperature. The performance of a very shallow geothermal system, as a horizontal collector or heat basket, is strongly correlated to the type of sediment at disposal and rapidly decreases in the case of dry-unsaturated conditions. The available experimental data are often scattered, incomplete and do not fully support thermo-active ground structure modeling. The ITER project, funded by the European Union, contributes to a better knowledge of the relationship between thermal conductivity and water content, required for understanding the very shallow geothermal systems behaviour in saturated and unsaturated conditions. So as to enhance the performance of horizontal geothermal heat exchangers, thermally enhanced backfilling material were tested in the laboratory, and an overview of physical-thermal properties variations under several moisture and load conditions for different mixtures of natural material was here presented.
VOC composition of current motor vehicle fuels and vapors, and collinearity analyses for receptor modeling

PubMed Central

Chin, Jo-Yu; Batterman, Stuart A.

2015-01-01

The formulation of motor vehicle fuels can alter the magnitude and composition of evaporative and exhaust emissions occurring throughout the fuel cycle. Information regarding the volatile organic compound (VOC) composition of motor fuels other than gasoline is scarce, especially for bioethanol and bio-diesel blends. This study examines the liquid and vapor (headspace) composition of four contemporary and commercially available fuels: gasoline (<10% ethanol), E85 (85% ethanol and 15% gasoline), ultra-low sulfur diesel (ULSD), and B20 (20% soy-biodiesel and 80% ULSD). The composition of gasoline and E85 in both neat fuel and headspace vapor was dominated by aromatics and n-heptane. Despite its low gasoline content, E85 vapor contained higher concentrations of several VOCs than those in gasoline vapor, likely due to adjustments in its formulation. Temperature changes produced greater changes in the partial pressures of 17 VOCs in E85 than in gasoline, and large shifts in the VOC composition. B20 and ULSD were dominated by C9 to C16 n-alkanes and low levels of the aromatics, and the two fuels had similar headspace vapor composition and concentrations. While the headspace composition predicted using vapor–liquid equilibrium theory was closely correlated to measurements, E85 vapor concentrations were underpredicted. Based on variance decomposition analyses, gasoline and diesel fuels and their vapors VOC were distinct, but B20 and ULSD fuels and vapors were highly collinear. These results can be used to estimate fuel related emissions and exposures, particularly in receptor models that apportion emission sources, and the collinearity analysis suggests that gasoline- and diesel-related emissions can be distinguished. PMID:22154341
Thermal regime of the Great Basin and its implications for enhanced geothermal systems and off-grid power

USGS Publications Warehouse

Sass, John H.; Walters, Mark A.

1999-01-01

The Basin and Range Province of the Western United States covers most of Nevada and parts of adjoining states. It was formed by east-west tectonic extension that occurred mostly between 50 and 10 Ma, but which still is active in some areas. The northern Basin and Range, also known as the Great Basin, is higher in elevation, has higher regional heat flow and is more tectonically active than the southern Basin and Range which encompasses the Mojave and Sonoran Deserts. The Great Basin terrane contains the largest number of geothermal power plants in the United States, although most electrical production is at The Geysers and in the Salton Trough. Installed capacities of electrical power plants in the Great Basin vary from 1 to 260 MWe. Productivity is limited largely by permeability, relatively small productive reservoir volumes, available water, market conditions and the availability of transmission lines. Accessible, in-place heat is not a limiting condition for geothermal systems in the Great Basin. In many areas, economic temperatures (>120°C) can be found at economically drillable depths making it an appropriate region for implementation of the concept of "Enhanced Geothermal Systems" (EGS). An incremental approach to EGS would involve increasing the productivity and longevity of existing hydrothermal systems. Those geothermal projects that have an existing power plant and transmission facilities are the most attractive EGS candidates. Sites that were not developed owing to marginal size, lack of intrinsic permeability, and distance to existing electrical grid lines are also worthy of consideration for off-grid power production in geographically isolated markets such as ranches, farms, mines, and smelters.
Predicting the growth of S i3N4 nanowires by phase-equilibrium-dominated vapor-liquid-solid mechanism

NASA Astrophysics Data System (ADS)

Zhang, Yongliang; Cai, Jing; Yang, Lijun; Wu, Qiang; Wang, Xizhang; Hu, Zheng

2017-09-01

Nanomaterial synthesis is experiencing a profound evolution from empirical science ("cook-and-look") to prediction and design, which depends on the deep insight into the growth mechanism. Herein, we report a generalized prediction of the growth of S i3N4 nanowires by nitriding F e28S i72 alloy particles across different phase regions based on our finding of the phase-equilibrium-dominated vapor-liquid-solid (PED-VLS) mechanism. All the predictions about the growth of S i3N4 nanowires, and the associated evolutions of lattice parameters and geometries of the coexisting Fe -Si alloy phases, are experimentally confirmed quantitatively. This progress corroborates the general validity of the PED-VLS mechanism, which could be applied to the design and controllable synthesis of various one-dimensional nanomaterials.
Geology of the Pavana geothermal area, Departamento de Choluteca, Honduras, Central America: Field report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Eppler, D.B.; Heiken, G.; Wohletz, K.

The Pavana geothermal area is located in southern Honduras near the Gulf of Fonseca. This region is underlain by late Tertiary volcanic rocks. Within ranges near the geothermal manifestations, the rock sequences is characterized by intermediate to mafic laharic breccias and lavas overlain by silicic tuffs and lavas, which are in turn overlain by intermediate to mafic breccias, lavas, and tuffs. The nearest Quaternary volcanoes are about 40 km to the southwest, where the chain of active Central American volcanoes crosses the mouth of the Gulf of Fonseca. Structure of the Pavana area is dominated by generally northwest-trending, southwest-dipping normalmore » faults. This structure is topographically expressed as northwest-trending escarpments that bound blocks of bedrock separated by asymmetric valleys that contain thin alluvial deposits. Thermal waters apparently issue from normal faults and are interpreted as having been heated during deep circulation along fault zones within a regional environment of elevated heat flow. Natural outflow from the main thermal area is about 3000 l/min of 60/sup 0/C water. Geothermometry of the thermal waters suggests a reservoir base temperature of about 150/sup 0/C.« less
2016 Geothermal Technologies Office Annual Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

None, None

This report highlights project successes and continued efforts in all of our program areas – EGS, Hydrothermal, Low-Temperature, and Systems Analysis – which are flanked by useful tools and resources and links to more information. Such highlights include FORGE and EGS successes, projects reducing geothermal costs and risks, and advancements in technology research and development.
Health and safety implications of alternative energy technologies. I. Geothermal and biomass

NASA Astrophysics Data System (ADS)

Watson, A. P.; Etnier, E. L.

1981-07-01

An evaluation of potential occupational and public health aspects of geopressure, hydrothermal, hot dry rock, silviculture, crop and animal residues, fermentable plant products, municipal waste, and plantation energy technologies has been performed. Future development of these energy options in the United States will contain hazards that could easily be eliminated by safer equipment design and common-sense attention to operation and maintenance. Occupational exposure to hydrogen sulfide gas occurs near all geothermal sites and wherever organic matter decomposes anaerobically. Respiratory damage has occurred to laborers in geothermal fields, while farm workers have been fatally overcome when employed near agitating liquid manure systems. However, the most frequent and severe of reported injuries to geothermal workers is dermal exposure to caustic sludges produced by H2S abatement systems. Principal health and safety considerations of biomass pathways are directly related to the diffuse nature of solar energy fixation by photosynthesis and subsequent transfer to animal food chains. Since the potential fuel is in an unconcentrated form, cultivation, harvest, and transport are necessarily laborintensive. Thus, a significant potential for occupational injuries and fatalities exists. Of all biomass systems evaluated, direct burning of solid fuels presents the greatest public health risk. Data are presented to characterize the population at risk and the frequency and severity of injuries.
Harsh Environment Silicon Carbide Sensor Technology for Geothermal Instrumentation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pisano, Albert P.

2013-04-26

This project utilizes Silicon Carbide (SiC) materials platform to fabricate advanced sensors to be used as high-temperature downhole instrumentation for the DOE’s Geothermal Technologies Program on Enhanced Geothermal Systems. The scope of the proposed research is to 1) develop a SiC pressure sensor that can operate in harsh supercritical conditions, 2) develop a SiC temperature sensor that can operate in harsh supercritical conditions, 3) develop a bonding process for adhering SiC sensor die to well casing couplers, and 4) perform experimental exposure testing of sensor materials and the sensor devices.
Identification of geothermal system using 2D audio magnetotelluric method in Telomoyo volcanic area

NASA Astrophysics Data System (ADS)

Romadlon, Arriqo'Fauqi; Niasari, Sintia Windhi

2017-07-01

Geothermal area of Candi Umbul Telomoyo is one of geothermal fields in Indonesia. This geothermal field is located in the Grabag district, Magelang, Central Java. This geothermal field was formed in a volcanic quarter. The main aim in this study is to identify geothermal system at Telomoyo volcanic area through synthetic model analysis. There are surface manifestations such as warm springs and altered rocks. Results of geochemistry study showed reservoir's temperature was 230°C. The Warm spring in Candi Umbul was the outflow zone of the Telomoyo geothermal system. The Telomoyo geothermal system was indicated chloride-bicarbonate type of warm spring. In addition, the results of geological mapping indicate that the dominant fault structure has southwest-northeast orientation. The fault was caused by the volcanic activity of mount Telomoyo. In this research conducted data analysis from synthetics model. It aims to estimate the response of magnetotelluric methods in various models of geothermal systems. In this study, we assumed three models of geothermal system in Candi Umbul-Telomoyo area. From the data analysis it was known that the model 1 and model 2 can be distinguished if the measurements were conducted in a frequency range of 0.01 Hz to 1000 Hz. In response of tipper (Hz) had a small value on all models at all measurement points, so the tipper cannot distinguish between model 1, model 2 and model 3. From this analysis was known that TM mode is more sensitive than TE mode at the resistivity and phase responses.
How Does Boiling in the Earth's Crust Influence Metal Speciation and Transport?

NASA Astrophysics Data System (ADS)

Kam, K.; Lemke, K.

2014-12-01

The presence of large quantities of precious metals, such as gold and copper, near the Earth's surface (upper crust) is commonly attributed to transport in aqueous solution and precipitation upon variations in temperature and pressure. As a consequence, gold exploration is closely linked to solution chemistry, i.e. hydrothermal processes involving aqueous fluids with densities of around unity. However, as crustal fluids buoyantly ascend, boiling produces a coexisting low-density aqueous liquid with fundamentally different physical and chemical properties, and a, most importantly, a high affinity for coinage metals (Heinrich et al., Econ Geol., 1992, 87, 1566). From recent experimental studies of Au (Hurtig and Williams-Jones, 2014, Geochim. Cosmochim. Acta,, 127, 304), we know that metal speciation in this low-density phase differs fundamentally from that observed in bulk solution, clearly, with important implications for Au, and metal speciation in general, transport and ore concentrations processes (these processes would also be operable in industrial geothermal plants given the quite special solvent properties of steam). In brief, this study focuses on the speciation of select metal halides in bulk solution as well as in water vapor, and is driven by our need to understand the solvent properties of around 2.0x109 cubic kilometers of free water (or 2,500 times as much water as stored in all lakes and rivers) present in the Earth's crust. The scope of this study has particular applications in the geothermal and oil industries, as both deal with high temperature low-density aqueous fluids. Understanding how metal halide species behave upon boiling can also provide insight into how metals, such as copper and silver, coat turbine equipment and steam piping in geothermal plants, ultimately rendering these components inoperable. This study will also provide preliminary results from mass spectrometric experiments of transition metal halides, and will be augmented with results from molecular simulations of metal halides that are aimed at characterizing the nature (i.e. relativistic structures and energies) of metal clusters in water vapor.
Origin and distribution of thiophenes and furans in gas discharges from active volcanoes and geothermal systems.

PubMed

Tassi, Franco; Montegrossi, Giordano; Capecchiacci, Francesco; Vaselli, Orlando

2010-03-31

The composition of non-methane organic volatile compounds (VOCs) determined in 139 thermal gas discharges from 18 different geothermal and volcanic systems in Italy and Latin America, consists of C(2)-C(20) species pertaining to the alkanes, alkenes, aromatics and O-, S- and N-bearing classes of compounds. Thiophenes and mono-aromatics, especially the methylated species, are strongly enriched in fluids emissions related to hydrothermal systems. Addition of hydrogen sulphide to dienes and electrophilic methylation involving halogenated radicals may be invoked for the formation of these species. On the contrary, the formation of furans, with the only exception of C(4)H(8)O, seems to be favoured at oxidizing conditions and relatively high temperatures, although mechanisms similar to those hypothesized for the production of thiophenes can be suggested. Such thermodynamic features are typical of fluid reservoirs feeding high-temperature thermal discharges of volcanoes characterised by strong degassing activity, which are likely affected by conspicuous contribution from a magmatic source. The composition of heteroaromatics in fluids naturally discharged from active volcanoes and geothermal areas can then be considered largely dependent on the interplay between hydrothermal vs. magmatic contributions. This implies that they can be used as useful geochemical tools to be successfully applied in both volcanic monitoring and geothermal prospection.
Microbiological Aspects of Geothermal Energy: Influence of Microbial Activity on Scaling and Clogging in a Cold Storage

NASA Astrophysics Data System (ADS)

Lerm, Stephanie; Alawi, Mashal; Miethling-Graff, Rona; Vieth, Andrea; Seibt, Andrea; Wolfgramm, Markus; Würdemann, Hilke

2010-05-01

The development of strategies to substantially reduce emission of greenhouse gases to the atmosphere is one of the major challenges of the next decades. Therefore, the utilization of subsurface stored energy arouses increasing interest. Corrosion and scaling are major problems in geothermal operation which create significant maintenance and cleaning costs. In the scope of the research project AquiScreen the operational reliability of geothermal used aquifer systems was investigated under microbial, geochemical, mineralogical, and petrologic aspects (see also Alawi et al.; General Assembly EGU 2010). This presentation focuses on the investigation of a cold storage in Berlin (Reichstag building, depth 30-50 m). In order to evaluate the impact of microbial processes in the low saline aquifer (see also Vetter et al.; General Assembly EGU 2010), the microbial communities of fluid and filter samples were investigated by Fluorescent in situ hybridization (FISH) and DNA fingerprinting techniques based on PCR amplified partial 16S rRNA genes. Analyses of fluid samples revealed a bacterial community dominated by iron and sulfur oxidizing bacteria closely related to Siderooxidans lithoautotrophicus, Gallionella sp. and Thiotrix unzii. Scanning electron microscope analysis revealed iron hydroxide formation and precipitation in the filter of the top side facility and the well, corresponding to the abundance of iron oxidizing bacteria. Besides oxidizing bacteria sulfate reducing bacteria (SRB) were detected as well, indicating the formation of micro-habitats with divergent redox zones. After several years of operation and routine maintenance procedures the injectivity of the injection wells and the endurance of the top side facility filters were reduced drastically due to clogging. Mechanical cleaning and a disinfection treatment with hydrogen peroxide (H2O2) were successful to re-establish the injectivity of the wells. The results of the microbiological investigations prove that bacteria and their metabolic activities were involved in the decrease of filter endurances. A strong biofilm formation of filamentous sulfur-oxidizing bacteria related to Thiothrix was observed. In the course of the disinfection measure the microbial composition in the process water changed significantly. Thiothrix could not be detected any longer and the biocoenosis in the fluid was dominated now by Flavobacterium, Acidovorax as well as Alcaligenaceae related organisms. In contrast, SRB analyzed by specific dissimilatory sulfite reductase genes were hardly affected by the disinfection measures. However, even if especially SRB are considered as the most important taxonomic group for microbiologically influenced corrosion (MIC), present operational results indicate that scaling and clogging were the predominant processes for the operation of the shallow cold storage in Berlin.
Materials for geothermal production

NASA Astrophysics Data System (ADS)

Kukacka, L. E.

Advances in the development of new materials continue to be made in the geothermal materials project. Many successes have already been accrued and the results used commercially. In FY-91, work was focused on reducing well drilling, fluid transport and energy conversion costs. Specific activities performed included lightweight CO2 resistant well cements, thermally conductive and scale resistant protective liner systems, chemical systems for lost circulation control, corrosion mitigation in process components at The Geysers, and elastomer-metal bonding systems. Efforts to transfer the technologies developed in these efforts to other energy-related sectors of the economy continued, and considerable success was achieved.
Geothermal Produced Fluids: Characteristics, Treatment Technologies, and Management Options

DOE Office of Scientific and Technical Information (OSTI.GOV)

Finster, Molly; Clark, Corrie; Schroeder, Jenna

2015-10-01

Geothermal power plants use geothermal fluids as a resource and create waste residuals as part of the power generation process. Both the geofluid resource and the waste stream are considered produced fluids. The chemical and physical nature of produced fluids can have a major impact on the geothermal power industry and can influence the feasibility of geothermal power development, exploration approaches, power plant design, operating practices, and the reuse or disposal of residuals. In general, produced fluids include anything that comes out of a geothermal field and that subsequently must be managed on the surface. These fluids vary greatly dependingmore » on the geothermal reservoir being harnessed, power plant design, and the life cycle stage in which the fluid exists, but generally include water and fluids used to drill geothermal wells, fluids used to stimulate wells in enhanced geothermal systems, and makeup and/or cooling water used during operation of a geothermal power plant. Additional geothermal-related produced fluids include many substances that are similar to waste streams from the oil and gas industry, such as scale, flash tank solids, precipitated solids from brine treatment, hydrogen sulfide, and cooling-tower-related waste. This review paper aims to provide baseline knowledge on specific technologies and technology areas associated with geothermal power production. Specifically, this research focused on the management techniques related to fluids produced and used during the operational stage of a geothermal power plant; the vast majority of which are employed in the generation of electricity. The general characteristics of produced fluids are discussed. Constituents of interest that tend to drive the selection of treatment technologies are described, including total dissolved solids, noncondensable gases, scale and corrosion, silicon dioxide, metal sulfides, calcium carbonate, corrosion, metals, and naturally occurring radioactive material. Management options for produced fluids that require additional treatment for these constituents are also discussed, including surface disposal, reuse and recycle, agricultural industrial and domestic uses, mineral extraction and recovery, and solid waste handling.« less
Design and Implementation of Geothermal Energy Systems at West Chester University

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cuprak, Greg

West Chester University has launched a comprehensive transformation of its campus heating and cooling systems from traditional fossil fuels (coal, oil and natural gas) to geothermal. This change will significantly decrease the institution’s carbon footprint and serve as a national model for green campus efforts. The institution has designed a phased series of projects to build a district geo-exchange system with shared well fields, central pumping station and distribution piping to provide the geo-exchange water to campus buildings as their internal building HVAC systems is changed to be able to use the geo-exchange water. This project addresses the US Departmentmore » of Energy Office of Energy Efficiency and Renewable Energy (EERE) goal to invest in clean energy technologies that strengthen the economy, protect the environment, and reduce dependence on foreign oil. In addition, this project advances EERE’s efforts to establish geothermal energy as an economically competitive contributor to the US energy supply.« less
Phylogenetic Diversity Analysis of Subterranean Hot Springs in Iceland

PubMed Central

Marteinsson, Viggó Thór; Hauksdóttir, Sigurbjörg; Hobel, Cédric F. V.; Kristmannsdóttir, Hrefna; Hreggvidsson, Gudmundur Oli; Kristjánsson, Jakob K.

2001-01-01

Geothermal energy has been harnessed and used for domestic heating in Iceland. In wells that are typically drilled to a depth of 1,500 to 2,000 m, the temperature of the source water is 50 to 130°C. The bottoms of the boreholes can therefore be regarded as subterranean hot springs and provide a unique opportunity to study the subterranean biosphere. Large volumes of geothermal fluid from five wells and a mixture of geothermal water from 50 geothermal wells (hot tap water) were sampled and concentrated through a 0.2-μm-pore-size filter. Cells were observed in wells RG-39 (91.4°C) and MG-18 (71.8°C) and in hot tap water (76°C), but no cells were detected in wells SN-4, SN-5 (95 to 117°C), and RV-5 (130°C). Archaea and Bacteria were detected by whole-cell fluorescent in situ hybridization. DNAs were extracted from the biomass, and small-subunit rRNA genes (16S rDNAs) were amplified by PCR using primers specific for the Archaea and Bacteria domains. The PCR products were cloned and sequenced. The sequence analysis showed 11 new operational taxonomic units (OTUs) out of 14, 3 of which were affiliated with known surface OTUs. Samples from RG-39 and hot tap water were inoculated into enrichment media and incubated at 65 and 85°C. Growth was observed only in media based on geothermal water. 16S rDNA analysis showed enrichments dominated with Desulfurococcales relatives. Two strains belonging to Desulfurococcus mobilis and to the Thermus/Deinococcus group were isolated from borehole RG-39. The results indicate that subsurface volcanic zones are an environment that provides a rich subsurface for novel thermophiles. PMID:11526029
Relative Importance of H2 and H2S as Energy Sources for Primary Production in Geothermal Springs▿ †

PubMed Central

D'Imperio, Seth; Lehr, Corinne R.; Oduro, Harry; Druschel, Greg; Kühl, Michael; McDermott, Timothy R.

2008-01-01

Geothermal waters contain numerous potential electron donors capable of supporting chemolithotrophy-based primary production. Thermodynamic predictions of energy yields for specific electron donor and acceptor pairs in such systems are available, although direct assessments of these predictions are rare. This study assessed the relative importance of dissolved H2 and H2S as energy sources for the support of chemolithotrophic metabolism in an acidic geothermal spring in Yellowstone National Park. H2S and H2 concentration gradients were observed in the outflow channel, and vertical H2S and O2 gradients were evident within the microbial mat. H2S levels and microbial consumption rates were approximately three orders of magnitude greater than those of H2. Hydrogenobaculum-like organisms dominated the bacterial component of the microbial community, and isolates representing three distinct 16S rRNA gene phylotypes (phylotype = 100% identity) were isolated and characterized. Within a phylotype, O2 requirements varied, as did energy source utilization: some isolates could grow only with H2S, some only with H2, while others could utilize either as an energy source. These metabolic phenotypes were consistent with in situ geochemical conditions measured using aqueous chemical analysis and in-field measurements made by using gas chromatography and microelectrodes. Pure-culture experiments with an isolate that could utilize H2S and H2 and that represented the dominant phylotype (70% of the PCR clones) showed that H2S and H2 were used simultaneously, without evidence of induction or catabolite repression, and at relative rate differences comparable to those measured in ex situ field assays. Under in situ-relevant concentrations, growth of this isolate with H2S was better than that with H2. The major conclusions drawn from this study are that phylogeny may not necessarily be reliable for predicting physiology and that H2S can dominate over H2 as an energy source in terms of availability, apparent in situ consumption rates, and growth-supporting energy. PMID:18641166

Towards understanding the puzzling lack of acid geothermal springs in Tibet (China): Insight from a comparison with Yellowstone (USA) and some active volcanic hydrothermal systems

USGS Publications Warehouse

Nordstrom, D. Kirk; Guo, Qinghai; McCleskey, R. Blaine

2014-01-01

Explanations for the lack of acid geothermal springs in Tibet are inferred from a comprehensive hydrochemical comparison of Tibetan geothermal waters with those discharged from Yellowstone (USA) and two active volcanic areas, Nevado del Ruiz (Colombia) and Miravalles (Costa Rica) where acid springs are widely distributed and diversified in terms of geochemical characteristic and origin. For the hydrothermal areas investigated in this study, there appears to be a relationship between the depths of magma chambers and the occurrence of acid, chloride-rich springs formed via direct magmatic fluid absorption. Nevado del Ruiz and Miravalles with magma at or very close to the surface (less than 1–2 km) exhibit very acidic waters containing HCl and H2SO4. In contrast, the Tibetan hydrothermal systems, represented by Yangbajain, usually have fairly deep-seated magma chambers so that the released acid fluids are much more likely to be fully neutralized during transport to the surface. The absence of steam-heated acid waters in Tibet, however, may be primarily due to the lack of a confining layer (like young impermeable lavas at Yellowstone) to separate geothermal steam from underlying neutral chloride waters and the possible scenario that the deep geothermal fluids below Tibet carry less H2S than those below Yellowstone.
Investigating ultra high-enthalpy geothermal systems: a collaborative initiative to promote scientific opportunities

NASA Astrophysics Data System (ADS)

Elders, W. A.; Nielson, D.; Schiffman, P.; Schriener, A., Jr.

2014-12-01

Scientists, engineers, and policy makers gathered at a workshop in the San Bernardino Mountains of southern California in October 2013 to discuss the science and technology involved in developing high-enthalpy geothermal fields. A typical high-enthalpy geothermal well between 2000 and 3000 m deep produces a mixture of hot water and steam at 200-300 °C that can be used to generate about 5-10 MWe of electric power. The theme of the workshop was to explore the feasibility and economic potential of increasing the power output of geothermal wells by an order of magnitude by drilling deeper to reach much higher pressures and temperatures. Development of higher enthalpy geothermal systems for power production has obvious advantages; specifically higher temperatures yield higher power outputs per well so that fewer wells are needed, leading to smaller environmental footprints for a given size of power plant. Plans for resource assessment and drilling in such higher enthalpy areas are already underway in Iceland, New Zealand, and Japan. There is considerable potential for similar developments in other countries that already have a large production of electricity from geothermal steam, such as Mexico, the Philippines, Indonesia, Italy, and the USA. However drilling deeper involves technical and economic challenges. One approach to mitigating the cost issue is to form a consortium of industry, government and academia to share the costs and broaden the scope of investigation. An excellent example of such collaboration is the Iceland Deep Drilling Project (IDDP), which is investigating the economic feasibility of producing electricity from supercritical geothermal reservoirs, and this approach could serve as model for future developments elsewhere. A planning committee was formed to explore creating a similar initiative in the USA.
Comparison of the microbial communities of hot springs waters and the microbial biofilms in the acidic geothermal area of Copahue (Neuquén, Argentina).

PubMed

Urbieta, María Sofía; González-Toril, Elena; Bazán, Ángeles Aguilera; Giaveno, María Alejandra; Donati, Edgardo

2015-03-01

Copahue is a natural geothermal field (Neuquén province, Argentina) dominated by the Copahue volcano. As a consequence of the sustained volcanic activity, Copahue presents many acidic pools, hot springs and solfataras with different temperature and pH conditions that influence their microbial diversity. The occurrence of microbial biofilms was observed on the surrounding rocks and the borders of the ponds, where water movements and thermal activity are less intense. Microbial biofilms are particular ecological niches within geothermal environments; they present different geochemical conditions from that found in the water of the ponds and hot springs which is reflected in different microbial community structure. The aim of this study is to compare microbial community diversity in the water of ponds and hot springs and in microbial biofilms in the Copahue geothermal field, with particular emphasis on Cyanobacteria and other photosynthetic species that have not been detected before in Copahue. In this study, we report the presence of Cyanobacteria, Chloroflexi and chloroplasts of eukaryotes in the microbial biofilms not detected in the water of the ponds. On the other hand, acidophilic bacteria, the predominant species in the water of moderate temperature ponds, are almost absent in the microbial biofilms in spite of having in some cases similar temperature conditions. Species affiliated with Sulfolobales in the Archaea domain are the predominant microorganism in high temperature ponds and were also detected in the microbial biofilms.
Microbiological Monitoring in Geothermal Plants

NASA Astrophysics Data System (ADS)

Alawi, M.; Lerm, S.; Linder, R.; Vetter, A.; Vieth-Hillebrand, A.; Miethling-Graff, R.; Seibt, A.; Wolfgramm, M.; Wuerdemann, H.

2010-12-01

In the scope of the research projects “AquiScreen” and “MiProTherm” we investigated geothermally used groundwater systems under microbial, geochemical, mineralogical and petrological aspects. On one side an enhanced process understanding of engineered geothermal systems is mandatory to optimize plant reliability and economy, on the other side this study provides insights into the microbiology of terrestrial thermal systems. Geothermal systems located in the North German Basin and the Molasse Basin were analyzed by sampling of fluids and solid phases. The investigated sites were characterized by different temperatures, salinities and potential microbial substrates. The microbial population was monitored by the use of genetic fingerprinting techniques and PCR-cloning based on PCR-amplified 16S rRNA and dissimilatory sulfite reductase (DSR) genes. DNA-sequences of fingerprints and cloned PCR-products were compared to public databases and correlated with metabolic classes to provide information about the biogeochemical processes. In all investigated geothermal plants, covering a temperature range from 5° to 120°C, microorganisms were found. Phylogenetic gene analyses indicate a broad diversity of microorganisms adapted to the specific conditions in the engineered system. Beside characterized bacteria like Thermus scotoductus, Siderooxidans lithoautotrophicus and the archaeon Methanothermobacter thermoautotrophicus a high number of so far uncultivated microorganisms was detected. As it is known that - in addition to abiotic factors - microbes like sulfate-reducing bacteria (SRB) are involved in the processes of corrosion and scaling in plant components, we identified SRB by specific analyses of DSR genes. The SRB detected are closely related to thermotolerant and thermophilic species of Desulfotomaculum, Thermodesulfovibrio, Desulfohalobium and Thermodesulfobacterium, respectively. Overall, the detection of microbes known to be involved in biocorrosion and the examined precipitation products like iron sulfides are indicating that microorganisms play an important role for the understanding of processes in engineered geothermal systems. The further identification of crucial process parameters influencing microbial activities will help to develop appropriate counter measures against microbial induced clogging and corrosion.
High Temperature 300°C Directional Drilling System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chatterjee, Kamalesh; Aaron, Dick; Macpherson, John

2015-07-31

Many countries around the world, including the USA, have untapped geothermal energy potential. Enhanced Geothermal Systems (EGS) technology is needed to economically utilize this resource. Temperatures in some EGS reservoirs can exceed 300°C. To effectively utilize EGS resources, an array of injector and production wells must be accurately placed in the formation fracture network. This requires a high temperature directional drilling system. Most commercial services for directional drilling systems are rated for 175°C while geothermal wells require operation at much higher temperatures. Two U.S. Department of Energy (DOE) Geothermal Technologies Program (GTP) projects have been initiated to develop a 300°Cmore » capable directional drilling system, the first developing a drill bit, directional motor, and drilling fluid, and the second adding navigation and telemetry systems. This report is for the first project, “High Temperature 300°C Directional Drilling System, including drill bit, directional motor and drilling fluid, for enhanced geothermal systems,” award number DE-EE0002782. The drilling system consists of a drill bit, a directional motor, and drilling fluid. The DOE deliverables are three prototype drilling systems. We have developed three drilling motors; we have developed four roller-cone and five Kymera® bits; and finally, we have developed a 300°C stable drilling fluid, along with a lubricant additive for the metal-to-metal motor. Metal-to-metal directional motors require coatings to the rotor and stator for wear and corrosion resistance, and this coating research has been a significant part of the project. The drill bits performed well in the drill bit simulator test, and the complete drilling system has been tested drilling granite at Baker Hughes’ Experimental Test Facility in Oklahoma. The metal-to-metal motor was additionally subjected to a flow loop test in Baker Hughes’ Celle Technology Center in Germany, where it ran for more than 100 hours.« less
Analytical model for the design of in situ horizontal permeable reactive barriers (HPRBs) for the mitigation of chlorinated solvent vapors in the unsaturated zone.

PubMed

Verginelli, Iason; Capobianco, Oriana; Hartog, Niels; Baciocchi, Renato

2017-02-01

In this work we introduce a 1-D analytical solution that can be used for the design of horizontal permeable reactive barriers (HPRBs) as a vapor mitigation system at sites contaminated by chlorinated solvents. The developed model incorporates a transient diffusion-dominated transport with a second-order reaction rate constant. Furthermore, the model accounts for the HPRB lifetime as a function of the oxidant consumption by reaction with upward vapors and its progressive dissolution and leaching by infiltrating water. Simulation results by this new model closely replicate previous lab-scale tests carried out on trichloroethylene (TCE) using a HPRB containing a mixture of potassium permanganate, water and sand. In view of field applications, design criteria, in terms of the minimum HPRB thickness required to attenuate vapors at acceptable risk-based levels and the expected HPRB lifetime, are determined from site-specific conditions such as vapor source concentration, water infiltration rate and HPRB mixture. The results clearly show the field-scale feasibility of this alternative vapor mitigation system for the treatment of chlorinated solvents. Depending on the oxidation kinetic of the target contaminant, a 1m thick HPRB can ensure an attenuation of vapor concentrations of orders of magnitude up to 20years, even for vapor source concentrations up to 10g/m 3 . A demonstrative application for representative contaminated site conditions also shows the feasibility of this mitigation system from an economical point of view with capital costs potentially somewhat lower than those of other remediation options, such as soil vapor extraction systems. Overall, based on the experimental and theoretical evaluation thus far, field-scale tests are warranted to verify the potential and cost-effectiveness of HPRBs for vapor mitigation control under various conditions of application. Copyright © 2017 Elsevier B.V. All rights reserved.
A market survey of geothermal wellhead power generation systems

NASA Technical Reports Server (NTRS)

Leeds, M. W.

1978-01-01

The market potential for a portable geothermal wellhead power conversion device is assessed. Major study objectives included identifying the most promising applications for such a system, the potential impediments confronting their industrialization, and the various government actions needed to overcome these impediments. The heart of the study was a series of structured interviews with key decision-making individual in the various disciplines of the geothermal community. In addition, some technical and economic analyses of a candidate system were performed to support the feasibility of the basic concept.
Water Use in Enhanced Geothermal Systems (EGS): Geology of U.S. Stimulation Projects, Water Costs, and Alternative Water Use Policies

DOE Data Explorer

Schroeder, Jenna N.

2014-12-16

According to the Energy Information Administration (EIA) of the U.S. Department of Energy (DOE), geothermal energy generation in the United States is projected to more than triple by 2040 (EIA 2013). This addition, which translates to more than 5 GW of generation capacity, is anticipated because of technological advances and an increase in available sources through the continued development of enhanced geothermal systems (EGSs) and low-temperature resources (EIA 2013). Studies have shown that air emissions, water consumption, and land use for geothermal electricity generation have less of an impact than traditional fossil fuel?based electricity generation; however, the long-term sustainability of geothermal power plants can be affected by insufficient replacement of aboveground or belowground operational fluid losses resulting from normal operations (Schroeder et al. 2014). Thus, access to water is therefore critical for increased deployment of EGS technologies and, therefore, growth of the geothermal sector. This paper examines water issues relating to EGS development from a variety of perspectives. It starts by exploring the relationship between EGS site geology, stimulation protocols, and below ground water loss, which is one of the largest drivers of water consumption for EGS projects. It then examines the relative costs of different potential traditional and alternative water sources for EGS. Finally it summarizes specific state policies relevant to the use of alternative water sources for EGS, and finally explores the relationship between EGS site geology, stimulation protocols, and below ground water loss, which is one of the largest drivers of water consumption for EGS projects.
Analysis of Geologic Parameters on the Performance of CO2-Plume Geothermal (CPG) Systems in a Multi-Layered Reservoirs

NASA Astrophysics Data System (ADS)

Garapati, N.; Randolph, J.; Saar, M. O.

2013-12-01

CO2-Plume Geothermal (CPG) involves injection of CO2 as a working fluid to extract heat from naturally high permeable sedimentary basins. The injected CO2 forms a large subsurface CO2 plume that absorbs heat from the geothermal reservoir and eventually buoyantly rises to the surface. The heat density of sedimentary basins is typically relatively low.However, this drawback is likely counteracted by the large accessible volume of natural reservoirs compared to artificial, hydrofractured, and thus small-scale, reservoirs. Furthermore, supercritical CO2has a large mobility (inverse kinematic viscosity) and expansibility compared to water resulting in the formation of a strong thermosiphon which eliminates the need for parasitic pumping power requirements and significantly increasing electricity production efficiency. Simultaneously, the life span of the geothermal power plant can be increased by operating the CPG system such that it depletes the geothermal reservoir heat slowly. Because the produced CO2 is reinjected into the ground with the main CO2 sequestration stream coming from a CO2 emitter, all of the CO2 is ultimately geologically sequestered resulting in a CO2 sequestering geothermal power plant with a negative carbon footprint. Conventional geothermal process requires pumping of huge amount of water for the propagation of the fractures in the reservoir, but CPG process eliminates this requirement and conserves water resources. Here, we present results for performance of a CPG system as a function of various geologic properties of multilayered systemsincludingpermeability anisotropy, rock thermal conductivity, geothermal gradient, reservoir depth and initial native brine salinity as well as spacing between the injection and production wells. The model consists of a 50 m thick, radially symmetric grid with a semi-analytic heat exchange and no fluid flow at the top and bottom boundaries and no fluid and heat flow at the lateral boundaries. We design Plackett-Burman experiments resulting in 16 simulations for the seven parameters investigated. The reservoir is divided into 3-, 4-, or 5- layer systems with log-normal permeability distributions. We consider 10 sets of values for each case resulting in a total of 16x3x10 =480 simulations.We analyze the performance of the system to maximize the amount of heat energy extracted, minimize reservoir temperature depletion and maximize the CO2concentration in the produced fluid. Achieving the latter objective reduces power system problems as Welch and Boyle (GRC Trans. 2009) found that CO2 concentration should be >94% in the systems they investigated.
Origin and Distribution of Thiophenes and Furans in Gas Discharges from Active Volcanoes and Geothermal Systems

PubMed Central

Tassi, Franco; Montegrossi, Giordano; Capecchiacci, Francesco; Vaselli, Orlando

2010-01-01

The composition of non-methane organic volatile compounds (VOCs) determined in 139 thermal gas discharges from 18 different geothermal and volcanic systems in Italy and Latin America, consists of C2–C20 species pertaining to the alkanes, alkenes, aromatics and O-, S- and N-bearing classes of compounds. Thiophenes and mono-aromatics, especially the methylated species, are strongly enriched in fluids emissions related to hydrothermal systems. Addition of hydrogen sulphide to dienes and electrophilic methylation involving halogenated radicals may be invoked for the formation of these species. On the contrary, the formation of furans, with the only exception of C4H8O, seems to be favoured at oxidizing conditions and relatively high temperatures, although mechanisms similar to those hypothesized for the production of thiophenes can be suggested. Such thermodynamic features are typical of fluid reservoirs feeding high-temperature thermal discharges of volcanoes characterised by strong degassing activity, which are likely affected by conspicuous contribution from a magmatic source. The composition of heteroaromatics in fluids naturally discharged from active volcanoes and geothermal areas can then be considered largely dependent on the interplay between hydrothermal vs. magmatic contributions. This implies that they can be used as useful geochemical tools to be successfully applied in both volcanic monitoring and geothermal prospection. PMID:20480029
NV PFA Regional Data

DOE Data Explorer

James Faulds

2015-10-28

This project focused on defining geothermal play fairways and development of a detailed geothermal potential map of a large transect across the Great Basin region (96,000 km2), with the primary objective of facilitating discovery of commercial-grade, blind geothermal fields (i.e. systems with no surface hot springs or fumaroles) and thereby accelerating geothermal development in this promising region. Data included in this submission consists of: structural settings (target areas, recency of faulting, slip and dilation potential, slip rates, quality), regional-scale strain rates, earthquake density and magnitude, gravity data, temperature at 3 km depth, permeability models, favorability models, degree of exploration and exploration opportunities, data from springs and wells, transmission lines and wilderness areas, and published maps and theses for the Nevada Play Fairway area.
Three-Dimensional Seismic Image of a Geothermal Prospect: Tinguiririca, Central Andes, Chile

NASA Astrophysics Data System (ADS)

Lira, E.; Comte, D.; Giavelli, A.; Clavero, J. E.; Pineda, G.

2010-12-01

Seismic monitoring has been widely used by the oil and gas industry, as a valuable input for the reservoir characterization. This tool has also been used in geothermal productive systems, particularly to understand permeability controls usually associated to shallow crustal fault systems that are seismically actives. Faults can be considered either “migration path” or “seals” in Petroleum Systems, depending on their activity story (they are carriers while actives and seals when the activity cease due to diagenetic processes in the fault plain). On the other hand, is well known that seismic velocities are strongly related to rock properties, in particular Vp/Vs and VpVs relationship has been successfully used to emphasize the variations in the physical rock properties due to fluid content and porosity. In geothermal systems, P and S-wave velocities are expected to be noticeably affected by massive hydrothermal alteration and/or to the presence of hot water in the fault related fractures of the rocks. In this job, the results of three months of seismic monitoring and a seismic velocity tomography are presented. Sixteen short period continuous recording, three components seismic stations were deployed in an area of approximately 20x10 Km2, and a large 8.8 magnitude earthquake took place during the recording period. The study area corresponds to the Tinguiririca volcanic complex (70°21''W, 35°48''S), in the high mountain of the Central Andes near the Chile-Argentina border. These preliminary results are complemented with some MT profiles, delineating potentially interesting geothermal features.
Completion Design Considerations for a Horizontal Enhanced Geothermal System

DOE Office of Scientific and Technical Information (OSTI.GOV)

Olson, Jeffrey; Eustes, Alfred; Fleckenstein, William

2015-09-02

The petroleum industry has had considerable success in recent decades in developing unconventional shale plays using horizontal drilling and multi-zonal isolation and stimulation techniques to fracture tight formations to enable the commercial production of oil and gas. Similar well completions could be used in Enhanced Geothermal Systems (EGS) to create multiple fractures from horizontal wells. This study assesses whether well completion techniques used in the unconventional shale industry to create multi-stage fractures can be applied to an enhanced geothermal system, with a focus on the completion of the EGS injection well. This study assumes an Enhanced Geothermal System (EGS) consistingmore » of a central horizontal injection well flanked on each side by horizontal production wells, connected to the injection well by multiple fractures. The focus is on the design and completion of the horizontal well. For the purpose of developing design criteria, a reservoir temperature of 200 degrees C (392 degrees F) and an injection well flow rate of 87,000 barrels per day (160 kg/s), corresponding to production well flow rates of 43,500 barrels per day (80 kg/s) is assumed. The analysis found that 9-5/8 inches 53.5 pounds per foot (ppf) P110 casing string with premium connections meets all design criteria for the horizontal section of injection well. A P110 grade is fairly common and is often used in horizontal sections of shale development wells in petroleum operations. Next, several zonal isolation systems commonly used in the shale gas industry were evaluated. Three techniques were evaluated -- a 'plug and perf' design, a 'sand and perf' design, and a 'packer and port' design. A plug and perf system utilizes a cemented casing throughout the length of the injector wellbore. The sand and perf system is identical to the plug and perf system, but replaces packers with sand placed in the casing after stimulation to screen out the stimulated perforated zones and provide zonal isolation. The packer and port completion approach utilizes an open horizontal hole that zonally isolates areas through the use of external packers and a liner. A review of technologies used in these systems was performed to determine if commercially available equipment from the petroleum industry could be used at the temperatures, pressures, and sizes encountered in geothermal settings. The study found no major technical barriers to employing shale gas multi-zonal completion techniques in a horizontal well in a geothermal setting for EGS development. For all techniques considered, temperature limitations of equipment are a concern. Commercially available equipment designed to operate at the high temperatures encountered in geothermal systems are available, but is generally unproven for geothermal applications. Based on the study, further evaluation of adapting oil and gas completion techniques to EGS is warranted.« less
Shallow geothermal potential of Cantone Ticino through map modeling

NASA Astrophysics Data System (ADS)

Perego, Rodolfo; Pera, Sebastian; Belliardi, Marco

2017-04-01

Low enthalpy geothermal energy is continuously growing in importance within Europe, since it is a reliable and efficient renewable energy, especially when exploited by closed-loop systems. Switzerland hosts one of the greatest density of low temperature geothermal systems in the world. Cantone Ticino includes more than 4000 probes, with an overall installed length of more than 500 km and the requests are continuously growing: the management of this technology must be therefore accurately faced both from a physical and political standpoint. The current authorization approach for closed-loop systems in Cantone Ticino, however, is mainly based on basic maps taking into account the presence of restrictions arising from the enforcement of the water protection act and ordinance. Closed-loop systems cannot be installed within S groundwater protection zones, and within the Au (usable groundwater) sector the installation of such systems is allowed in specific areas where the presence of conflicts precludes groundwater exploitation for drinking purposes. The described procedure, however, does not consider the subsurface potential nor the techno-economic constraints. More empirically based maps could instead give precious planning indications and they could also be useful, if properly verified, to perform pre-emptive estimates of technical and economic parameters. The procedure for the mapping of the geothermal potential started with the identification of the main parameters affecting it, such as the ground surface temperature (GST), thermal conductivity of both outcrops/unconsolidated material and heat flux/geothermal gradient. Maps for all of these parameters were created and some of them were compared with real measurement data, with satisfactory results. The estimated error for the ground temperature reconstruction was quantified in ±1°C, while the error of the hydraulic conductivity reconstruction was estimated as half of an order of magnitude. A reference set of thermal properties was then assigned to each lithological unit (both rocky and sedimentary) according to SIA 384/6 regulation and a thermal conductivity map (for outcrops and equivalent Quaternary deposits) was produced. 128 simulations with EED software varying λ, GST and heat flux were then performed in order to find a regression that could allow calculating for the whole region the total borehole length required to satisfy a hypothesized annual heat demand of 30 MWh/year. BHE length map was then verified against 967 real systems and the overall error was quantified in approximately 21% (±27m). Maps of technological, economical and market indexes were finally produced also with the help a newly developed economic tool. Geothermal potential maps were also compared with the current authorization map and the disparity was clearly observable: the areas where new closed loop systems are currently allowed often represent the ones with a lower geothermal potential. This means that a revision of the authorization process is necessary in order to have a more optimized management of this resource that could also take into account the natural, technological and economic constraints. In parallel, the verified maps proposed in this work proved to be a reliable instrument to pre-emptively perform semi-quantitative estimates for new GSHP systems.
Calc-silicate mineralization in active geothermal systems

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bird, D.K.; Schiffman, P.; Elders, W.A.

The detailed study of calc-silicate mineral zones and coexisting phase relations in the Cerro Prieto geothermal system were used as examples for thermodynamic evaluation of phase relations among minerals of variable composition and to calculate the chemical characteristics of hydrothermal solutions compatible with the observed calc-silicate assemblages. In general there is a close correlation between calculated and observed fluid compositions. Calculated fugacities of O{sub 2} at about 320{degrees}C in the Cerro Prieto geothermal system are about five orders of magnitude less than that at the nearby Salton Sea geothermal system. This observation is consistent with the occurrence of Fe{sup 3+}more » rich epidotes in the latter system and the presence of prehnite at Cerro Prieto.« less
Water Use in Enhanced Geothermal Systems (EGS): Geology of U.S. Stimulation Projects, Water Costs, and Alternative Water Source Policies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harto, C. B.; Schroeder, J. N.; Horner, R. M.

According to the Energy Information Administration (EIA) of the U.S. Department of Energy (DOE), geothermal energy generation in the United States is projected to more than triple by 2040 (EIA 2013). This addition, which translates to more than 5 GW of generation capacity, is anticipated because of technological advances and an increase in available sources through the continued development of enhanced geothermal systems (EGSs) and low-temperature resources (EIA 2013). Studies have shown that air emissions, water consumption, and land use for geothermal electricity generation have less of an impact than traditional fossil fuel–based electricity generation; however, the long-term sustainability ofmore » geothermal power plants can be affected by insufficient replacement of aboveground or belowground operational fluid losses resulting from normal operations (Schroeder et al. 2014). Thus, access to water is therefore critical for increased deployment of EGS technologies and, therefore, growth of the geothermal sector. This paper examines water issues relating to EGS development from a variety of perspectives. It starts by exploring the relationship between EGS site geology, stimulation protocols, and below ground water loss, which is one of the largest drivers of water consumption for EGS projects. It then examines the relative costs of different potential traditional and alternative water sources for EGS. Finally it summarizes specific state policies relevant to the use of alternative water sources for EGS, and finally explores the relationship between EGS site geology, stimulation protocols, and below ground water loss, which is one of the largest drivers of water consumption for EGS projects.« less
Comparison of circulation times of thermal waters discharging from the Idaho batholith based on geothermometer temperatures, helium concentrations, and 14C measurements

USGS Publications Warehouse

Mariner, R.H.; Evans, William C.; Young, H.W.

2006-01-01

Circulation times of waters in geothermal systems are poorly known. In this study, we examine the thermal waters of the Idaho batholith to verify whether maximum system temperatures, helium concentrations, and 14C values are related to water age in these low-to-moderate temperature geothermal systems. He/N2 values of gas collected from thermal waters that circulate solely through distinct units of the Idaho batholith correlate linearly with Na-K-(4/3)Ca geothermometer temperatures, showing that both variables are excellent indicators of relative water age. Thermal waters that circulate in early Tertiary (45-50 Ma) granite of the Sawtooth batholith have 3.5 times more helium than thermal waters of the same aquifer temperature that circulate through the main Cretaceous granite (average 91 Ma). Hot spring waters circulating in hydrothermally altered parts of the batholith have very little dissolved helium and no correlation between He/N2 values and geothermometer temperatures. Thermal waters discharging from the Idaho batholith are more depleted in deuterium than modern precipitation in the area. Recharge to these geothermal systems occurred from at least 10,000 BP for the cooler systems up to about 33,000 BP for the hotter systems.
Alternative Geothermal Power Production Scenarios

DOE Data Explorer

Sullivan, John

2014-03-14

The information given in this file pertains to Argonne LCAs of the plant cycle stage for a set of ten new geothermal scenario pairs, each comprised of a reference and improved case. These analyses were conducted to compare environmental performances among the scenarios and cases. The types of plants evaluated are hydrothermal binary and flash and Enhanced Geothermal Systems (EGS) binary and flash plants. Each scenario pair was developed by the LCOE group using GETEM as a way to identify plant operational and resource combinations that could reduce geothermal power plant LCOE values. Based on the specified plant and well field characteristics (plant type, capacity, capacity factor and lifetime, and well numbers and depths) for each case of each pair, Argonne generated a corresponding set of material to power ratios (MPRs) and greenhouse gas and fossil energy ratios.
Analysis of Low-Temperature Utilization of Geothermal Resources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anderson, Brian

Full realization of the potential of what might be considered “low-grade” geothermal resources will require that we examine many more uses for the heat than traditional electricity generation. To demonstrate that geothermal energy truly has the potential to be a national energy source we will be designing, assessing, and evaluating innovative uses for geothermal-produced water such as hybrid biomass-geothermal cogeneration of electricity and district heating and efficiency improvements to the use of cellulosic biomass in addition to utilization of geothermal in district heating for community redevelopment projects. The objectives of this project were: 1) to perform a techno-economic analysis ofmore » the integration and utilization potential of low-temperature geothermal sources. Innovative uses of low-enthalpy geothermal water were designed and examined for their ability to offset fossil fuels and decrease CO2 emissions. 2) To perform process optimizations and economic analyses of processes that can utilize low-temperature geothermal fluids. These processes included electricity generation using biomass and district heating systems. 3) To scale up and generalize the results of three case study locations to develop a regionalized model of the utilization of low-temperature geothermal resources. A national-level, GIS-based, low-temperature geothermal resource supply model was developed and used to develop a series of national supply curves. We performed an in-depth analysis of the low-temperature geothermal resources that dominate the eastern half of the United States. The final products of this study include 17 publications, an updated version of the cost estimation software GEOPHIRES, and direct-use supply curves for low-temperature utilization of geothermal resources. The supply curves for direct use geothermal include utilization from known hydrothermal, undiscovered hydrothermal, and near-hydrothermal EGS resources and presented these results at the Stanford Geothermal Workshop. We also have incorporated our wellbore model into TOUGH2-EGS and began coding TOUGH2-EGS with the wellbore model into GEOPHIRES as a reservoir thermal drawdown option. Additionally, case studies for the WVU and Cornell campuses were performed to assess the potential for district heating and cooling at these two eastern U.S. sites.« less
Preliminary Study of 2-D Time Domain Electromagnetic (TDEM) Modeling to Analyze Subsurface Resistivity Distribution and its Application to the Geothermal Systems

NASA Astrophysics Data System (ADS)

Aji Hapsoro, Cahyo; Purqon, Acep; Srigutomo, Wahyu

2017-07-01

2-D Time Domain Electromagnetic (TDEM) has been successfully conducted to illustrate the value of Electric field distribution under the Earth surface. Electric field compared by magnetic field is used to analyze resistivity and resistivity is one of physical properties which very important to determine the reservoir potential area of geothermal systems as one of renewable energy. In this modeling we used Time Domain Electromagnetic method because it can solve EM field interaction problem with complex geometry and to analyze transient problems. TDEM methods used to model the value of electric and magnetic fields as a function of the time combined with the function of distance and depth. The result of this modeling is Electric field intensity value which is capable to describe the structure of the Earth’s subsurface. The result of this modeling can be applied to describe the Earths subsurface resistivity values to determine the reservoir potential of geothermal systems.

Second law analysis of advanced power generation systems using variable temperature heat sources

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bliem, C.J.; Mines, G.L.

1990-01-01

Many systems produce power using variable temperature (sensible) heat sources. The Heat Cycle Research Program is currently investigating the potential improvements to such power cycles utilizing moderate temperature geothermal resources to produce electrical power. It has been shown that mixtures of saturated hydrocarbons (alkanes) or halogenated hydrocarbons operating with a supercritical Rankine cycle gave improved performance over boiling Rankine cycles with the pure working fluids for typical applications. Recently, in addition to the supercritical Rankine Cycle, other types of cycles have been proposed for binary geothermal service. This paper explores the limits on efficiency of a feasible plant and discussesmore » the methods used in these advanced concept plants to achieve the maximum possible efficiency. The advanced plants considered appear to be approaching the feasible limit of performance so that the designer must weigh all considerations to fine the best plant for a given service. These results would apply to power systems in other services as well as to geothermal power plants. 17 refs., 15 figs.« less
7 CFR 4279.108 - Eligible borrowers.

Code of Federal Regulations, 2013 CFR

2013-01-01

... reliance on nonrenewable energy resources by encouraging the development and construction of solar energy systems and other renewable energy systems (including wind energy systems, geothermal energy systems, and anaerobic digesters for the purpose of energy generation). (b) Citizenship. Individual borrowers must be...
On the use of flow-storage repartitions derived from artificial tracer tests for geothermal reservoir characterization in the Malm-Molasse basin: a theoretical study

NASA Astrophysics Data System (ADS)

Dewi, Dina Silvia; Osaigbovo Enomayo, Augustine; Mohsin, Rizwan; Karmakar, Shyamal; Ghergut, Julia; Sauter, Martin

2016-04-01

Flow-storage repartition (FSR) analysis (Shook 2003) is a versatile tool for characterizing subsurface flow and transport systems. FSR can be derived from measured signals of inter-well tracer tests, if certain requirements are met - basically, the same as required for equivalence between fluid residence time distribution (RTD) and a measured inter-well tracer signal (pre-processed and de-convolved if necessary). Nominally, a FSR is derived from a RTD as a trajectory in normalized {1st, 0th}-order statistical moment space; more intuitively, as a parametric plot of 0th-order against 1st-order statistical moments of RTD truncated at time t, with t as a parameter running from the first tracer input to the latest available tracer sampling; 0th-order moments being normalized by the total tracer recovery, and 1st-order moments by the mean RT. Fracture-dominated systems plot in the upper left (high F , low S) region of FSR diagrams; a homogeneous single-continuum with no dispersion (infinite Peclet number) displays a straight line from {F ,S}={0,0} to {F ,S}={1,1}. This analysis tool appears particularly attractive for characterizing markedly-heterogeneous, porous-fissured-fractured (partly karstified) formations like those targeted by geothermal exploration in the Malm-Molasse basin in Southern Germany, and especially for quantifying flow and transport contributions from contrasting facies types ('reef' versus 'bedded'). However, tracer tests conducted in such systems with inter-well distances of some hundreds of metres (as required by economic considerations on geothermal reservoir sizing) face the problem of very long residence times - and thus the need to deal with incomplete (truncated) signals. For the geothermal well triplet at the Sauerlach site near Munich, tracer peak arrival times exceeding 2 years have been predicted, and signal tails decreasing by less than 50% over >10 years, which puts great uncertainty on the (extrapolation-based) normalizing factors needed to calculate FSR. Looking at the Sauerlach example, we find that premature interruption of tracer sampling systematically leads to overestimating the reservoir's storage capacity and underestimating its flow capacity, with misestimation generally increasing as the bedded/reef interfacial area per volume is increased. It is interesting to correlate these findings with the tracer-based approach to facies identification for the shallower Malm aquifers of the Southern Franconian Alb, proposed by Seiler et al. (1989, 1995) and with expectations from the direct (i. e., distributed-parameter) modeling of matrix-diffusive effects (Maloszewski and Zuber 1985) on measured tracer signals. References: Maloszewski P, Zuber A (1985) On the theory of tracer experiments in fissured rocks with a porous matrix, Journal of Hydrology, 79, 333-358 Seiler K-P, Behrens H, Wolf M (1995) Use of artificial and environmental tracers to study storage and drainage of groundwater in the Franconian Alb, Germany, and the consequences for groundwater protection, Proc Isotopes in Water Resources Management, 2, 135-146 (IAEA, Vienna) Seiler K-P, Maloszewski P, Behrens H (1989) Hydrodynamic dispersion in karstified limestones and dolomites in the Upper Jurassic of the Franconian Alb, FRG, Journal of Hydrology, 108, 235-247 Shook G M (2003) A Simple, Fast Method of Estimating Fractured Reservoir Geometry from Tracer Tests, Geothermal Resources Council Transactions, 27, 407-411 Financial support from the German Federal Ministry for Economic Affairs and Energy is gratefully acknowledged. - Gefördert durch BMWi aufgrund eines Beschlusses des Deutschen Bundestages (FKZ 0325515 "TRENDS").
DOE Office of Scientific and Technical Information (OSTI.GOV)

Davlin, Thomas

The overall deliverable from the project is the design, construction and commissioning of a detention facility heating and cooling system that minimizes ownership costs and maximizes efficiency (and therefore minimizes environmental impact). The primary deliverables were the proof of concept for the application of geothermal systems for an institutional facility and the ongoing, quarterly system operating data downloads to the Department of Energy . The primary advantage of geothermal based heat pump systems is the higher efficiency of the system compared to a conventional chiller, boiler, cooling tower based system. The higher efficiency results in a smaller environmental foot printmore » and lower energy costs for the detention facility owner, Lancaster County. The higher efficiency for building cooling is primarily due to a more constant compressor condensing temperature with the geothermal well field acting as a thermal “sink” (in place of the conventional system’s cooling tower). In the heating mode, Ground Couple Heat Pump (GCHP) systems benefits from the advantage of a heat pump Coefficient of Performance (COP) of approximately 3.6, significantly better than a conventional gas boiler. The geothermal well field acting as a thermal “source” allows the heat pumps to operate efficiently in the heating mode regardless of ambient temperatures. The well field is partially located in a wetland with a high water table so, over time, the project will be able to identify the thermal loading characteristics of a well field located in a high water table location. The project demonstrated how a large geothermal well field can be installed in a wetland area in an economical and environmentally sound manner. Finally, the SW 40th Street Thermal Energy Plant project demonstrates the benefits of providing domestic hot water energy, as well as space heating, to help balance well filed thermal loading in a cooling dominated application. During the period of August 2012 thru March 2014, with the detention facility occupied for the final seven months, the well field supply water temperatures to the heat pumps dropped to a minimum of 39°F and reached a maximum temperature of 68 °F while providing 15,819 MMBtu of cooling energy and 27,467 MMBtu of heating energy. During this period the peak recorded system cooling load was 610 tons and the peak heating load was 8.4 MMBtu. The DEC is currently evaluating the most beneficial electric rate for plant operations. Total project cost of $16.9 million was approximately $3.2 million less than the estimate provided in the grant application. The reduction in project costs were primarily due to favorable construction material prices as well as strong competition in the local construction contractor market. The DEC plant reached the substantial completion milestone in December 2011 and began providing thermal service to the detention facility in January 2012 when the building’s HVAC system was ready to accept heating service. The plant reached commercial operating status on August 1, 2012. However, due to construction delays, the detention facility was not occupied until September of 2013. The detention facility construction delays also impacted the installation and commissioning of the project’s dedicated domestic hot water heat pump. Final coordination with the detention facility’s building management system vendor to establish network links for the exchange of date is currently being completed. This will allow the development of control sequences for the optimal operation of the domestic hot water system.« less
Geothermal flux through palagonitized tephra, Surtsey, Iceland - The Surtsey temperature-data-relay experiment via Landsat-1

NASA Technical Reports Server (NTRS)

Friedman, J. D.; Preble, D. M.; Jakobsson, S.

1976-01-01

The net geothermal flux through palagonitized basaltic tephra rims of the Surtur I and Surtur II craters at Surtsey, Iceland, in 1972, is estimated at 780 plus or minus 325 microcal/sq cm/s, indicating a decline since 1969 when a flux of 1500 microcal/sq cm/s was estimated. Heat flux in this range characterizes the postvolcanic environment on Surtsey in which the subaerial polagonitization of basaltic tephra is associated with mass transfer of hydrothermal vapor, either of meteoric or sea-water origin, only a few years after cessation of eruptive activity. The flux estimation is the result of the Surtsey data-relay experiment via Landsat-1 which was carried out in several phases. Temperature data were transmitted for a 38-day period in November and December 1972. A near-surface vertical gradient of 69.4 C/m was obtained, suggesting a mixed mechanism of heat transfer, partitioned between conduction and convection.
7 CFR 4279.108 - Eligible borrowers.

Code of Federal Regulations, 2010 CFR

2010-01-01

... reliance on nonrenewable energy resources by encouraging the development and construction of solar energy systems and other renewable energy systems (including wind energy systems, geothermal energy systems, and anaerobic digesters for the purpose of energy generation). (b) Citizenship. Individual borrowers must be...
7 CFR 4279.108 - Eligible borrowers.

Code of Federal Regulations, 2012 CFR

2012-01-01

... reliance on nonrenewable energy resources by encouraging the development and construction of solar energy systems and other renewable energy systems (including wind energy systems, geothermal energy systems, and anaerobic digesters for the purpose of energy generation). (b) Citizenship. Individual borrowers must be...
Hydrologic models of modern and fossil geothermal systems in the Great Basin: Genetic implications for epithermal Au-Ag and Carlin-type gold deposits

USGS Publications Warehouse

Person, M.; Banerjee, A.; Hofstra, A.; Sweetkind, D.; Gao, Y.

2008-01-01

The Great Basin region in the western United States contains active geothermal systems, large epithermal Au-Ag deposits, and world-class Carlin-type gold deposits. Temperature profiles, fluid inclusion studies, and isotopic evidence suggest that modern and fossil hydrothermal systems associated with gold mineralization share many common features, including the absence of a clear magmatic fluid source, discharge areas restricted to fault zones, and remarkably high temperatures (>200 ??C) at shallow depths (200-1500 m). While the plumbing of these systems varies, geochemical and isotopic data collected at the Dixie Valley and Beowawe geothermal systems suggest that fluid circulation along fault zones was relatively deep (>5 km) and comprised of relatively unexchanged Pleistocene meteoric water with small (<2.5%) shifts from the meteoric water line (MWL). Many fossil ore-forming systems were also dominated by meteoric water, but usually exhibit ??18O fluid-rock interactions with larger shifts of 5???-20??? from the MWL. Here we present a suite of two-dimensional regional (100 km) and local (40-50 km) scale hydrologic models that we have used to study the plumbing of modern and Tertiary hydrothermal systems of the Great Basin. Geologically and geophysically consistent cross sections were used to generate somewhat idealized hydrogeologic models for these systems that include the most important faults, aquifers, and confining units in their approximate configurations. Multiple constraints were used, including enthalpy, ??18O, silica compositions of fluids and/or rocks, groundwater residence times, fluid inclusion homogenization temperatures, and apatite fission track anomalies. Our results suggest that these hydrothermal systems were driven by natural thermal convection along anisotropic, subvertical faults connected in many cases at depth by permeable aquifers within favorable lithostratigraphic horizons. Those with minimal fluid ?? 18O shifts are restricted to high-permeability fault zones and relatively small-scale (???5 km), single-pass flow systems (e.g., Beowawe). Those with intermediate to large isotopic shifts (e.g., epithermal and Carlin-type Au) had larger-scale (???15 km) loop convection cells with a greater component of flow through marine sedimentary rocks at lower water/rock ratios and greater endowments of gold. Enthalpy calculations constrain the duration of Carlin-type gold systems to probably <200 k.y. Shallow heat flow gradients and fluid silica concentrations suggest that the duration of the modern Beowawe system is <5 k.y. However, fluid flow at Beowawe during the Quaternary must have been episodic with a net duration of ???200 k.y. to account for the amount of silica in the sinter deposits. In the Carlin trend, fluid circulation extended down into Paleozoic siliciclastic rocks, which afforded more mixing with isotopically enriched higher enthalpy fluids. Computed fission track ages along the Carlin trend included the convective effects, and ranged between 91.6 and 35.3 Ma. Older fission track ages occurred in zones of groundwater recharge, and the younger ages occurred in discharge areas. This is largely consistent with fission track ages reported in recent studies. We found that either an amagmatic system with more permeable faults (10-11 m2) or a magmatic system with less permeable faults (10-13 m2) could account for the published isotopic and thermal data along the Carlin trend systems. Localized high heat flow beneath the Muleshoe fault was needed to match fl uid inclusion temperatures at Mule Canyon. However, both magmatic and amagmatic scenarios require the existence of deep, permeable faults to bring hot fluids to the near surface. ?? 2008 Geological Society of America.
Rock geochemistry related to mineralization processes in geothermal areas

NASA Astrophysics Data System (ADS)

Kausar, A. Al; Indarto, S.; Setiawan, I.

2018-02-01

Abundant geothermal systems in Indonesia suggest high heat and mass transfer associated with recent or paleovolcanic arcs. In the active geothermal system, the upflow of mixed fluid between late stage hydrothermal and meteoric water might contain mass of minerals associated with epithermal mineralisation process as exemplified at Lihir gold mine in Papua New Guinea. In Indonesia, there is a lack of study related to the precious metals occurrence within active geothermal area. Therefore, in this paper, we investigate the possibility of mineralization process in active geothermal area of Guci, Central Java by using geochemical analysis. There are a lot of conducted geochemical analysis of water, soil and gas by mapping the temperature, pH, Hg and CO2 distribution, and estimating subsurface temperature based on geothermometry approach. Then we also apply rock geochemistry to find minerals that indicate the presence of mineralization. The result from selected geothermal area shows the presence of pyrite and chalcopyrite minerals on the laharic breccias at Kali Putih, Sudikampir. Mineralization is formed within host rock and the veins are associated with gold polymetallic mineralization.
Natural geochemical analogues of the near field of high-level nuclear waste repositories

DOE Office of Scientific and Technical Information (OSTI.GOV)

Apps, J.A.

1995-09-01

United States practice has been to design high-level nuclear waste (HLW) geological repositories with waste densities sufficiently high that repository temperatures surrounding the waste will exceed 100{degrees}C and could reach 250{degrees}C. Basalt and devitrified vitroclastic tuff are among the host rocks considered for waste emplacement. Near-field repository thermal behavior and chemical alteration in such rocks is expected to be similar to that observed in many geothermal systems. Therefore, the predictive modeling required for performance assessment studies of the near field could be validated and calibrated using geothermal systems as natural analogues. Examples are given which demonstrate the need for refinementmore » of the thermodynamic databases used in geochemical modeling of near-field natural analogues and the extent to which present models can predict conditions in geothermal fields.« less
Dixie Valley Engineered Geothermal System Exploration Methodology Project, Baseline Conceptual Model Report

DOE Data Explorer

Joe Iovenitti

2013-05-15

The Engineered Geothermal System (EGS) Exploration Methodology Project is developing an exploration approach for EGS through the integration of geoscientific data. The Project chose the Dixie Valley Geothermal System in Nevada as a field laboratory site for methodlogy calibration purposes because, in the public domain, it is a highly characterized geothermal systems in the Basin and Range with a considerable amount of geoscience and most importantly, well data. This Baseline Conceptual Model report summarizes the results of the first three project tasks (1) collect and assess the existing public domain geoscience data, (2) design and populate a GIS database, and (3) develop a baseline (existing data) geothermal conceptual model, evaluate geostatistical relationships, and generate baseline, coupled EGS favorability/trust maps from +1km above sea level (asl) to -4km asl for the Calibration Area (Dixie Valley Geothermal Wellfield) to identify EGS drilling targets at a scale of 5km x 5km. It presents (1) an assessment of the readily available public domain data and some proprietary data provided by Terra-Gen Power, LLC, (2) a re-interpretation of these data as required, (3) an exploratory geostatistical data analysis, (4) the baseline geothermal conceptual model, and (5) the EGS favorability/trust mapping. The conceptual model presented applies to both the hydrothermal system and EGS in the Dixie Valley region.
Double-diffusive convection in geothermal systems: the salton sea, California, geothermal system as a likely candidate

USGS Publications Warehouse

Fournier, R.O.

1990-01-01

Much has been published about double-diffusive convection as a mechanism for explaining variations in composition and temperature within all-liquid natural systems. However, relatively little is known about the applicability of this phenomenon within the heterogeneous rocks of currently active geothermal systems where primary porosity may control fluid flow in some places and fractures may control it in others. The main appeal of double-diffusive convection within hydrothermal systems is-that it is a mechanism that may allow efficient transfer of heat mainly by convection, while at the same time maintaining vertical and lateral salinity gradients. The Salton Sea geothermal system exhibits the following reservoir characteristics: (1) decreasing salinity and temperature from bottom to top and center toward the sides, (2) a very high heat flow from the top of the system that seems to require a major component of convective transfer of heat within the chemically stratified main reservoir, and (3) a relatively uniform density of the reservoir fluid throughout the system at all combinations of subsurface temperature, pressure, and salinity. Double-diffusive convection can account for these characteristics very nicely whereas other previously suggested models appear to account either for the thermal structure or for the salinity variations, but not both. Hydrologists, reservoir engineers, and particularly geochemists should consider the possibility and consequences of double-diffusive convection when formulating models of hydrothermal processes, and of the response of reservoirs to testing and production. ?? 1990.
Experiments Demonstrate Geothermal Heating Process

ERIC Educational Resources Information Center

Roman, Harry T.

2012-01-01

When engineers design heat-pump-based geothermal heating systems for homes and other buildings, they can use coil loops buried around the perimeter of the structure to gather low-grade heat from the earth. As an alternative approach, they can drill well casings and store the summer's heat deep in the earth, then bring it back in the winter to warm…
Microbiological monitoring in geothermal plants and a cold storage

NASA Astrophysics Data System (ADS)

Alawi, Mashal; Lerm, Stephanie; Vieth, Andrea; Vetter, Alexandra; Miethling-Graff, Rona; Seibt, Andrea; Wolfgramm, Markus; Würdemann, Hilke

2010-05-01

Enhanced process understanding of engineered geothermal systems is mandatory to optimize plant reliability and economy. In the scope of the research project 'AquiScreen' we investigated geothermally used groundwater systems under microbial, geochemical, mineralogical and petrological aspects. Geothermal systems located in the North German Basin and the Molasse Basin were analyzed by sampling of fluids and solid phases. The investigated sites were characterized by different temperatures, salinities and potential microbial substrates. The microbial population was analyzed by the use of genetic fingerprinting techniques based on PCR-amplified 16S rRNA genes. Sequencing of dominant bands of fingerprints from different sites and the subsequent comparison on public databases enables a correlation to metabolic classes and provides information about the biochemical processes. In all investigated geothermal plants covering a temperature range from 45° to 120° C microorganisms were found. Phylogenetic gene analyses indicate a broad diversity of microorganisms adapted to the specific conditions in the engineered system. Beside characterized bacteria like Thermus scotoductus, Siderooxidans lithoautotrophicus and the archaeon Methanothermobacter thermoautotrophicus a high number of so far uncultivated microorganisms was detected. As it is known that -in addition to abiotic factors- microbes like sulfate-reducing bacteria (SRB) are involved in the processes of corrosion and scaling in plant components we identified SRB by specific analyses of dissimilatoric sulfite reductase genes. The SRB detected are closely related to thermotolerant and thermophilic species of Desulfotomaculum, Thermodesulfovibrio and Thermodesulfobacterium, respectively. Overall, the detection of microbes known to be involved in biocorrosion and examined precipitation products like iron sulfides are indicating that microorganisms play an important role for the understanding of processes in engineered geothermal systems. Furthermore, an observed reduction of the filter operation times in a cold storage could be traced back to an enhanced growth of a filamentous iron-oxidizing bacterium related to Thiotrix. The further identificaton of crucial process parameters that are influencing microbial activities will help developing appropriate counter measures against microbial induced clogging and corrosion.
TOUGH2Biot - A simulator for coupled thermal-hydrodynamic-mechanical processes in subsurface flow systems: Application to CO2 geological storage and geothermal development

NASA Astrophysics Data System (ADS)

Lei, Hongwu; Xu, Tianfu; Jin, Guangrong

2015-04-01

Coupled thermal-hydrodynamic-mechanical processes have become increasingly important in studying the issues affecting subsurface flow systems, such as CO2 sequestration in deep saline aquifers and geothermal development. In this study, a mechanical module based on the extended Biot consolidation model was developed and incorporated into the well-established thermal-hydrodynamic simulator TOUGH2, resulting in an integrated numerical THM simulation program TOUGH2Biot. A finite element method was employed to discretize space for rock mechanical calculation and the Mohr-Coulomb failure criterion was used to determine if the rock undergoes shear-slip failure. Mechanics is partly coupled with the thermal-hydrodynamic processes and gives feedback to flow through stress-dependent porosity and permeability. TOUGH2Biot was verified against analytical solutions for the 1D Terzaghi consolidation and cooling-induced subsidence. TOUGH2Biot was applied to evaluate the thermal, hydrodynamic, and mechanical responses of CO2 geological sequestration at the Ordos CCS Demonstration Project, China and geothermal exploitation at the Geysers geothermal field, California. The results demonstrate that TOUGH2Biot is capable of analyzing change in pressure and temperature, displacement, stress, and potential shear-slip failure caused by large scale underground man-made activity in subsurface flow systems. TOUGH2Biot can also be easily extended for complex coupled process problems in fractured media and be conveniently updated to parallel versions on different platforms to take advantage of high-performance computing.
3D Geological Model for "LUSI" - a Deep Geothermal System

NASA Astrophysics Data System (ADS)

Sohrabi, Reza; Jansen, Gunnar; Mazzini, Adriano; Galvan, Boris; Miller, Stephen A.

2016-04-01

Geothermal applications require the correct simulation of flow and heat transport processes in porous media, and many of these media, like deep volcanic hydrothermal systems, host a certain degree of fracturing. This work aims to understand the heat and fluid transport within a new-born sedimentary hosted geothermal system, termed Lusi, that began erupting in 2006 in East Java, Indonesia. Our goal is to develop conceptual and numerical models capable of simulating multiphase flow within large-scale fractured reservoirs such as the Lusi region, with fractures of arbitrary size, orientation and shape. Additionally, these models can also address a number of other applications, including Enhanced Geothermal Systems (EGS), CO2 sequestration (Carbon Capture and Storage CCS), and nuclear waste isolation. Fractured systems are ubiquitous, with a wide-range of lengths and scales, making difficult the development of a general model that can easily handle this complexity. We are developing a flexible continuum approach with an efficient, accurate numerical simulator based on an appropriate 3D geological model representing the structure of the deep geothermal reservoir. Using previous studies, borehole information and seismic data obtained in the framework of the Lusi Lab project (ERC grant n°308126), we present here the first 3D geological model of Lusi. This model is calculated using implicit 3D potential field or multi-potential fields, depending on the geological context and complexity. This method is based on geological pile containing the geological history of the area and relationship between geological bodies allowing automatic computation of intersections and volume reconstruction. Based on the 3D geological model, we developed a new mesh algorithm to create hexahedral octree meshes to transfer the structural geological information for 3D numerical simulations to quantify Thermal-Hydraulic-Mechanical-Chemical (THMC) physical processes.
Honey Lake Power Facility under construction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1988-12-01

Geothermal energy and wood waste are primary energy sources for the 30 megawatt, net, Honey Lake Power Facility, a cogeneration power plant. The facility 60% completed in January 1989, will use 1,300 tons per day of fuel obtained from selective forest thinnings and from logging residue combined with mill wastes. The power plant will be the largest industrial facility to use some of Lassen County's geothermal resources. The facility will produce 236 million kilowatt-hours of electricity annually. The plant consists of a wood-fired traveling grate furnace with a utility-type high pressure boiler. Fluids from a geothermal well will pass throughmore » a heat exchange to preheat boiler feedwater. Used geothermal fluid will be disposed of in an injection well. Steam will be converted to electrical power through a 35.5-megawatt turbine generator and transmitted 22 miles to Susanville over company-owned and maintained transmission lines. The plant includes pollution control for particulate removal, ammonia injection for removal of nitrogen oxides, and computer-controlled combustion systems to control carbon monoxide and hydrocarbons. The highly automated wood yard consists of systems to remove metal, handle oversized material, receive up to six truck loads of wood products per hour, and continuously deliver 58 tons per hour of fuel through redundant systems to ensure maximum on-line performance. The plant is scheduled to become operational in mid-1989.« less
Energy balance and economic feasibility of shallow geothermal systems for winery industry

NASA Astrophysics Data System (ADS)

Ruiz-Mazarrón, F.; Almoguera-Millán, J.; García-Llaneza, J.; Perdigones, A.

2012-04-01

The search of energy efficient solutions has not yet been accomplished in agro-food constructions, for which technical studies and orientations are needed to find energy efficient solutions adapted to the environment. The main objective of this investigation is to evaluate the effectiveness of using shallow geothermal energy for the winery industry. World wine production in 2009 stood at 27100 millions of litres [1]. World spends 320 billion Euros on wine a year, according to industry insiders. On average, it is estimated that producing 1 litre of wine sold in a 75 cl glass bottle costs around 0.5-1.2 Euros /litre [2]. The process of ageing the wine could substantially increase production costs. Considering the time required for the aging of wine (months or years) and the size of the constructions, the use of an air conditioning system implies a considerable increase in energy consumption. Underground wine cellars have been in use for centuries for making and ageing wine. Ground thermal inertia provides protection from outdoor temperature oscillation and maintains thermal stability without energy consumption [3]. Since the last century, production of wine has moved to buildings above ground that have several advantages: lower construction cost, more space, etc. Nevertheless, these constructions require a large energy consumption to maintain suitable conditions for the ageing and conservation of wine. This change of construction techniques is the cause of an increase in energy consumption in modern wineries. The use of shallow geothermal energy can be a good alternative to take advantage of the benefits of aboveground buildings and underground constructions simultaneously. Shallow geothermal systems can meet the needs of heating and cooling using a single installation, maintaining low energy consumption. Therefore, it could be a good alternative to conventional HVAC systems. The main disadvantage of geothermal systems is the high cost of investment required. This paper analyzes the use of shallow geothermal systems in wineries, studying its feasibility versus conventional HVAC systems. A comparative analysis of six European locations will be performed. [1] OIV, Assessment on the world vitiviniculture situation in 2010, in, Organisation Internationale de la Vigne et du Vin, 2010. [2] FAO, Agribusiness Handbook: Grapes Wine, in, Investment Centre Division. FAO, 2009. [3] F.R. Mazarrón, J. Cid-Falceto, I. Cañas, An assessment of using ground thermal inertia as passive thermal technique in the wine industry around the world, Applied Thermal Engineering, 33-34 (0) (2012) 54-61.
Mapping temperature and radiant geothermal heat flux anomalies in the Yellowstone geothermal system using ASTER thermal infrared data

USGS Publications Warehouse

Vaughan, R. Greg; Lowenstern, Jacob B.; Keszthelyi, Laszlo P.; Jaworowski, Cheryl; Heasler, Henry

2012-01-01

The purpose of this work was to use satellite-based thermal infrared (TIR) remote sensing data to measure, map, and monitor geothermal activity within the Yellowstone geothermal area to help meet the missions of both the U.S. Geological Survey Yellowstone Volcano Observatory and the Yellowstone National Park Geology Program. Specifically, the goals were to: 1) address the challenges of remotely characterizing the spatially and temporally dynamic thermal features in Yellowstone by using nighttime TIR data from the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and 2) estimate the temperature, geothermal radiant emittance, and radiant geothermal heat flux (GHF) for Yellowstone’s thermal areas (both Park wide and for individual thermal areas). ASTER TIR data (90-m pixels) acquired at night during January and February, 2010, were used to estimate surface temperature, radiant emittance, and radiant GHF from all of Yellowstone’s thermal features, produce thermal anomaly maps, and update field-based maps of thermal areas. A background subtraction technique was used to isolate the geothermal component of TIR radiance from thermal radiance due to insolation. A lower limit for the Yellowstone’s total radiant GHF was established at ~2.0 GW, which is ~30-45% of the heat flux estimated through geochemical (Cl-flux) methods. Additionally, about 5 km2 was added to the geodatabase of mapped thermal areas. This work provides a framework for future satellite-based thermal monitoring at Yellowstone as well as exploration of other volcanic / geothermal systems on a global scale.
Hydrogen Fluxes from Photosynthetic Communities: Implications for Early Earth Biogeochemistry

NASA Technical Reports Server (NTRS)

Hoehler, Tori M.; Bebout, Brad M.; DesMarais, David J.; DeVincenzi, Donald L. (Technical Monitor)

2000-01-01

More than half the history of life on Earth was dominated by photosynthetic microbial mats, which must have represented the preeminent biological influence on global geochemical cycling during that time. In modem analogs of then ancient communities, hypersaline microbial mats from Guerrero Negro, Mexico, we have observed a large flux of molecular hydrogen originating in the cyanobacteria-dominated surface layers. Hydrogen production follows a distinct diel pattern and is sensitive to both oxygen tension and microbial species composition within the mat. On an early Earth dominated by microbial mats, the observed H2 fluxes would scale to global levels far in excess of geothermal emissions. A hydrogen flux of this magnitude represents a profound transmission of reducing power from oxygenic photosynthesis, both to the anaerobic biosphere, where H2 is an almost universally-utilized substrate and regulator of microbial redox chemistry, and to the atmosphere, where subsequent escape to space could provide an important mechanism for the net oxidation of Earth's surface.

7 CFR 4279.108 - Eligible borrowers.

Code of Federal Regulations, 2011 CFR

2011-01-01

... reliance on nonrenewable energy resources by encouraging the development and construction of solar energy systems and other renewable energy systems (including wind energy systems, geothermal energy systems, and anaerobic digesters for the purpose of energy generation). (b) Citizenship. Individual borrowers must be...
7 CFR 4279.108 - Eligible borrowers.

Code of Federal Regulations, 2014 CFR

2014-01-01

... reliance on nonrenewable energy resources by encouraging the development and construction of solar energy systems and other renewable energy systems (including wind energy systems, geothermal energy systems, and anaerobic digesters for the purpose of energy generation). (b) Citizenship. Individual borrowers must be...
Innovative computational tools for reducing exploration risk through integration of water-rock interactions and magnetotelluric surveys

DOE Office of Scientific and Technical Information (OSTI.GOV)

Moore, Joseph

2017-04-20

Mapping permeability distributions in geothermal reservoirs is essential for reducing the cost of geothermal development. To avoid the cost and sampling bias of measuring permeability directly through drilling, we require remote methods of imaging permeability such as geophysics. Electrical resistivity (or its inverse, conductivity) is one of the most sensitive geophysical properties known to reflect long range fluid interconnection and thus the likelihood of permeability. Perhaps the most widely applied geophysical methods for imaging subsurface resistivity is magnetotellurics (MT) due to its relatively great penetration depths. A primary goal of this project is to confirm through ground truthing at existingmore » geothermal systems that MT resistivity structure interpreted integratively is capable of revealing permeable fluid pathways into geothermal systems.« less
A geographically weighted regression model for geothermal potential assessment in mediterranean cultural landscape

NASA Astrophysics Data System (ADS)

D'Arpa, S.; Zaccarelli, N.; Bruno, D. E.; Leucci, G.; Uricchio, V. F.; Zurlini, G.

2012-04-01

Geothermal heat can be used directly in many applications (agro-industrial processes, sanitary hot water production, heating/cooling systems, etc.). These applications respond to energetic and environmental sustainability criteria, ensuring substantial energy savings with low environmental impacts. In particular, in Mediterranean cultural landscapes the exploitation of geothermal energy offers a valuable alternative compared to other exploitation systems more land-consuming and visual-impact. However, low enthalpy geothermal energy applications at regional scale, require careful design and planning to fully exploit benefits and reduce drawbacks. We propose a first example of application of a Geographically Weighted Regression (GWR) for the modeling of geothermal potential in the Apulia Region (South Italy) by integrating hydrological (e.g. depth to water table, water speed and temperature), geological-geotechnical (e.g. lithology, thermal conductivity) parameters and land-use indicators. The GWR model can effectively cope with data quality, spatial anisotropy, lack of stationarity and presence of discontinuities in the underlying data maps. The geothermal potential assessment required a good knowledge of the space-time variation of the numerous parameters related to the status of geothermal resource, a contextual analysis of spatial and environmental features, as well as the presence and nature of regulations or infrastructures constraints. We create an ad hoc geodatabase within ArcGIS 10 collecting relevant data and performing a quality assessment. Cross-validation shows high level of consistency of the spatial local models, as well as error maps can depict areas of lower reliability. Based on low enthalpy geothermal potential map created, a first zoning of the study area is proposed, considering four level of possible exploitation. Such zoning is linked and refined by the actual legal constraints acting at regional or province level as enforced by the regional plan for the protection of the landscape ("Piano Urbanistico Territoriale Tematico Paesaggio"), the regional plan for the protection of water and groundwater ("Piano di Tutela delle Acque"), the regional plan of hydrogeological risk ("Piano di Assetto Idrogeologico") and the province level master-plan for the development ("Piano Territoriale di Coordinamento Provinciale"). We believe our results can be a substantial contribution for the ongoing regional debate on the exploitation of geothermal potential as well as an important knowledge base for the integration of such topic in the new regional energetic and environmental plan ("Piano Energetico Ambientale Regionale").
Assessing the Impact of the Installation of a Community-Scale Closed-Loop Ground-Source Geothermal System on Underlying Aquifers: Ball State University, Muncie, IN

NASA Astrophysics Data System (ADS)

Neumann, K.; Dowling, C.; Florea, L.; Dunn, M.; Samuelson, A. C.; Lowe, J.

2013-12-01

Ball State University (BSU), located within the city of Muncie, Indiana, began installing the nation's largest ground-source geothermal project in 2009. Currently, BSU is burning over 20,000 tons of coal annually to satisfy heating and cooling demands of the school and is one of the largest emitters of CO2, SO2 and mercury in the city of Muncie and surrounding Delaware County. The elimination of coal burning will reduce aerial pollution by an estimated 1400 tons of SO2 and 4 pounds of mercury annually, once the system is fully operational. Currently, the groundsource geothermal system is being installed in Phases. Phase 1 includes 1803 400-ft deep geothermal boreholes that were drilled in a 15x15 ft grid in two large fields (North and South) in the northern part of campus. Two geothermal exchange loops were installed in each borehole to add or remove heat from the ground. BSU students and faculty collected hydrogeologic and temperature data from a series of groundwater monitoring wells, beginning Summer 2010. The installation of the second phase in the southern part of campus has commenced.. Despite the rise in community-scale ground-source geothermal energy systems, there is very little empirical information on their effects upon the groundwater environment, or, vice versa, of the effects of the groundwater flow pattern on the geothermal field. Previous studies have triggered concern over the impact of large-scale geothermal systems where increases in groundwater temperatures were documented. We will demonstrate how, since BSU initiated Phase 1 in late November 2011 with cold-water circulation (adding heat to the ground), the temperature increased over 10 degrees Celsius in the center of the South Field, with temperatures rising in other surrounding monitoring wells depending on groundwater movement and their distance from the edge of the geothermal boreholes. The temperature increases are distinctively different in the upper highly hydraulically conductive aquifers (Quaternary till) and the underlying poorly conductive formations (Ordovician and Silurian limestone and shale). Maintaining a temperature differential between the exchange loops and the geologic substrate and/or groundwater is crucial to the long term efficiency of the system, and continued monitoring both of the hydrology and engineering aspects of the project will be necessary.
Low temperature geothermal systems in carbonate-evaporitic rocks: Mineral equilibria assumptions and geothermometrical calculations. Insights from the Arnedillo thermal waters (Spain).

PubMed

Blasco, Mónica; Gimeno, María J; Auqué, Luis F

2018-02-15

Geothermometrical calculations in low-medium temperature geothermal systems hosted in carbonate-evaporitic rocks are complicated because 1) some of the classical chemical geothermometers are, usually, inadequate (since they were developed for higher temperature systems with different mineral-water equilibria at depth) and 2) the chemical geothermometers calibrated for these systems (based on the Ca and Mg or SO 4 and F contents) are not free of problems either. The case study of the Arnedillo thermal system, a carbonate-evaporitic system of low temperature, will be used to deal with these problems through the combination of several geothermometrical techniques (chemical and isotopic geothermometers and geochemical modelling). The reservoir temperature of the Arnedillo geothermal system has been established to be in the range of 87±13°C being the waters in equilibrium with respect to calcite, dolomite, anhydrite, quartz, albite, K-feldspar and other aluminosilicates. Anhydrite and quartz equilibria are highly reliable to stablish the reservoir temperature. Additionally, the anhydrite equilibrium explains the coherent results obtained with the δ 18 O anhydrite - water geothermometer. The equilibrium with respect to feldspars and other aluminosilicates is unusual in carbonate-evaporitic systems and it is probably related to the presence of detrital material in the aquifer. The identification of the expected equilibria with calcite and dolomite presents an interesting problem associated to dolomite. Variable order degrees of dolomite can be found in natural systems and this fact affects the associated equilibrium temperature in the geothermometrical modelling and also the results from the Ca-Mg geothermometer. To avoid this uncertainty, the order degree of the dolomite present in the Arnedillo reservoir has been determined and the results indicate 18.4% of ordered dolomite and 81.6% of disordered dolomite. Overall, the results suggest that this multi-technique approach is very useful to solve some of the problems associated to the study of carbonate-evaporitic geothermal systems. Copyright © 2017 Elsevier B.V. All rights reserved.
Chlorite dissolution kinetics at pH 3–10 and temperature to 275°C

DOE Office of Scientific and Technical Information (OSTI.GOV)

Smith, Megan M.; Carroll, Susan A.

Sheet silicates and clays are ubiquitous in geothermal environments. Their dissolution is of interest because this process contributes to scaling reactions along fluid pathways and alteration of fracture surfaces which could affect reservoir permeability. Here, in order to better predict the geochemical impacts on long-term performance of engineered geothermal systems, we have measured chlorite dissolution and developed a generalized kinetic rate law applicable over an expanded range of solution pH and temperature. Chlorite, (Mg,Al,Fe) 12(Si,Al) 8O 20(OH) 16, commonly occurs in many geothermal host rocks as either a primary mineral or alteration product.
Abrupt physical and chemical changes during 1992-1999, Anderson Springs, SE Geyser Geothermal Field, California

USGS Publications Warehouse

Janik, Cathy J.; Goff, Fraser; Walter, Stephen R.; Sorey, Michael L.; Counce, Dale; Colvard, Elizabeth M.

2000-01-01

The Anderson Springs area is located about 90 miles (145 kilometers) north of San Francisco, California, in the southwestern part of Lake County. The area was first developed in the late 1800s as a health resort, which was active until the 1930s. Patrons drank a variety of cool to hot mineral waters from improved springs, swam in various baths and pools, and hiked in the rugged hills flanking Anderson Creek and its tributaries. In the bluffs to the south of the resort were four small mercury mines of the eastern Mayacmas quicksilver district. About 1,260 flasks of mercury were produced from these mines between 1909 and 1943. By the early 1970s, the higher ridges south and west of Anderson Springs became part of the southeast sector of the greater Geysers geothermal field. Today, several electric power plants are built on these ridges, producing energy from a vapor-dominated 240 °C reservoir. Only the main hot spring at Anderson Springs has maintained a recognizable identity since the 1930s. The hot spring is actually a cluster of seeps and springs that issue from a small fault in a ravine southwest of Anderson Creek. Published and unpublished records show that the maximum temperature (Tm) of this cluster fell gradually from 63°C in 1889 to 48°C in 1992. However, Tm of the cluster climbed to 77°C in 1995 and neared boiling (98°C) in 1998. A new cluster of boiling vents and small fumaroles (Tm = 99.3°C) formed in 1998 about 30 m north of the old spring cluster. Several evergreen trees on steep slopes immediately above these vents apparently were killed by the new activity. Thermal waters at Anderson Hot Springs are mostly composed of near-surface ground waters with some added gases and condensed steam from The Geysers geothermal system. Compared to gas samples from Southeast Geysers wells, the hot spring gases are higher in CO2 and lower in H2S and NH3. As the springs increased in temperature, however, the gas composition became more like the mean composition of steam discharges from the Southeast Geysers. The hot spring waters are low in ions of Cl, B, and Li, but relatively high in HCO3, SO4 and NH4. The stable-isotope compositions (deuterium and oxygen-18) of these waters plot near the global meteoric water line. Geochemical data through time reveal apparent maxima in the concentrations of SO4, Fe, and Mn in 1991 to 1992, before the cluster became hotter. The black-to-gray deposits from the new spring cluster are rich in pyrite and contain anomalous metals. About one-half mile to the east of the hot springs, mineralized water discharges intermittently from an old adit of the Schwartz (Anderson) mine, and enters a tributary of Anderson Creek. This drainage increased substantially in July 1998, and a slurry of mine water and precipitates were transported down the tributary and into Anderson Creek. In December 1998, the adit water was 22°C, and had a chemical composition that was similar to spring waters that once discharged in the ravines surrounding the old Anderson Springs resort. The cause for the abrupt changes that have occurred in thermal features at Anderson Springs is still not resolved. One possibility is that these changes are a response to withdrawal of steam from The Geysers geothermal field over more than 20 years of production. Pressure declines in the geothermal reservoir may have caused a "drying out" of the overlying condensation zone. Induced boiling in this zone and upflow of deep steam to shallower depths would cause heating and vaporization of shallow ground waters. In addition, earthquakes occurring in the vicinity of Anderson Springs have increased significantly after nearby geothermal power plants began operation. These earthquakes may have enhanced surface discharge of thermal fluids along fractures and faults.
The effect of the dynamic wet troposphere on radio interferometric measurements

NASA Technical Reports Server (NTRS)

Treuhaft, R. N.; Lanyi, G. E.

1987-01-01

A statistical model of water vapor fluctuations is used to describe the effect of the dynamic wet troposphere on radio interferometric measurements. It is assumed that the spatial structure of refractivity is approximated by Kolmogorov turbulence theory, and that the temporal fluctuations are caused by spatial patterns moved over a site by the wind, and these assumptions are examined for the VLBI delay and delay rate observables. The results suggest that the delay rate measurement error is usually dominated by water vapor fluctuations, and water vapor induced VLBI parameter errors and correlations are determined as a function of the delay observable errors. A method is proposed for including the water vapor fluctuations in the parameter estimation method to obtain improved parameter estimates and parameter covariances.
MOUNT HOOD WILDERNESS AND ADJACENT AREAS, OREGON.

USGS Publications Warehouse

Keith, T.E.C.; Causey, J.D.

1984-01-01

A mineral survey of the Mount Hood Wilderness, Oregon, was conducted. Geochemical data indicate two areas of substantiated mineral-resource potential containing weak epithermal mineralization: an area of the north side of Zigzag Mountain where vein-type lead-zinc-silver deposits occur and an area of the south side of Zigzag Mountain, where the upper part of a quartz diorite pluton has propylitic alteration associated with mineralization of copper, gold, silver, lead, and zinc in discontinuous veins. Geothermal-resource potential for low- to intermediate-temperature (less than 248 degree F) hot-water systems in the wilderness is probable in these areas. Part of the wilderness is classified as a Known Geothermal Resource Area (KGRA), which is considered to have probable geothermal-resource potential, and two parts of the wilderness have been included in geothermal lease areas.
Chlorite dissolution kinetics at pH 3–10 and temperature to 275°C

DOE PAGES

Smith, Megan M.; Carroll, Susan A.

2015-12-02

Sheet silicates and clays are ubiquitous in geothermal environments. Their dissolution is of interest because this process contributes to scaling reactions along fluid pathways and alteration of fracture surfaces which could affect reservoir permeability. Here, in order to better predict the geochemical impacts on long-term performance of engineered geothermal systems, we have measured chlorite dissolution and developed a generalized kinetic rate law applicable over an expanded range of solution pH and temperature. Chlorite, (Mg,Al,Fe) 12(Si,Al) 8O 20(OH) 16, commonly occurs in many geothermal host rocks as either a primary mineral or alteration product.
Environmental Impacts of a Multi-Borehole Geothermal System: Model Sensitivity Study

NASA Astrophysics Data System (ADS)

Krol, M.; Daemi, N.

2017-12-01

Problems associated with fossil fuel consumption has increased worldwide interest in discovering and developing sustainable energy systems. One such system is geothermal heating, which uses the constant temperature of the ground to heat or cool buildings. Since geothermal heating offers low maintenance, high heating/cooling comfort, and a low carbon footprint, compared to conventional systems, there has been an increasing trend in equipping large buildings with geothermal heating. However, little is known on the potential environmental impact geothermal heating can have on the subsurface, such as the creation of subsurface thermal plumes or changes in groundwater flow dynamics. In the present study, the environmental impacts of a closed-loop, ground source heat pump (GSHP) system was examined with respect to different system parameters. To do this a three-dimensional model, developed using FEFLOW, was used to examine the thermal plumes resulting from ten years of operation of a vertical closed-loop GSHP system with multiple boreholes. A required thermal load typical of an office building located in Canada was calculated and groundwater flow and heat transport in the geological formation was simulated. Consequently, the resulting thermal plumes were studied and a sensitivity analysis was conducted to determine the effect of different parameters like groundwater flow and soil type on the development and movement of thermal plumes. Since thermal plumes can affect the efficiency of a GSHP system, this study provides insight into important system parameters.
QEMSCAN° (Quantitative Evaluation of Minerals by Scanning Electron Microscopy): capability and application to fracture characterization in geothermal systems

NASA Astrophysics Data System (ADS)

Ayling, B.; Rose, P. E.; Zemach, E.; Drakos, P. S.; Petty, S.

2011-12-01

Fractures are important conduits for fluids in geothermal systems, and the creation and maintenance of fracture permeability is a fundamental aspect of EGS (Engineered Geothermal System) development. Hydraulic or chemical stimulation techniques are often employed to achieve this. In the case of chemical stimulation, an understanding of the minerals present in the fractures themselves is desirable to better design a stimulation effort (i.e. which chemical to use and how much). Borehole televiewer surveys provide important information about regional and local stress regimes and fracture characteristics (e.g. fracture aperture), and XRD is useful for examining bulk rock mineralogy, but neither technique is able to quantify the distribution of these minerals in fractures. QEMSCAN° is a fully-automated micro-analysis system that enables quantitative chemical analysis of materials and generation of high-resolution mineral maps and images as well as porosity structure. It uses a scanning electron microscopy platform (SEM) with an electron beam source in combination with four energy-dispersive X-ray spectrometers (EDS). The measured backscattered electron and electron-induced secondary X-ray emission spectra are used to classify sample mineralogy. Initial applications of QEMSCAN° technology were predominantly in the minerals industry and application to geothermal problems has remained limited to date. In this pilot study, the potential application of QEMSCAN° technology to fracture characterization was evaluated using samples of representative mineralized fractures in two geothermal systems (Newberry Volcano, Oregon and Brady's geothermal field, Nevada). QEMSCAN° results were compared with XRD and petrographic techniques. Nine samples were analyzed from each field, collected from the drill core in the 1000-1500 m depth range in two shallow wells (GEO-N2 at Newberry Volcano and BCH-3 at Brady's). The samples were prepared as polished thin sections for QEMSCAN° analysis. Results indicate that a sampling resolution of 10 μm is sufficient to resolve fracture morphology and mineral zonation (where multiple episodes of mineralization occurred), and enables relatively fast data acquisition (3 cm2 can be analyzed in approximately 3 hours). Finer resolutions (down to 2.5 μm) take significantly longer, but can be used to provide additional spatial detail in areas of interest after a low resolution (10 μm) scan. Use of XRD data in conjunction with QEMSCAN° data is sometimes needed to distinguish geothermal alteration minerals with similar chemical compositions (clay minerals, micas and chlorite), however overall the technique appears to have excellent potential for geothermal applications.
Broadband Magnetotelluric Investigations of Crustal Resistivity Structure in North-Eastern Alberta: Implications for Engineered Geothermal Systems

NASA Astrophysics Data System (ADS)

Liddell, M. V.; Unsworth, M. J.; Nieuwenhuis, G.

2013-12-01

Greenhouse gas emissions from hydrocarbon consumption produce profound changes in the global climate, and the implementation of alternative energy sources is needed. The oilsands industry in Alberta (Canada) is a major producer of greenhouse gases as natural gas is burnt to produce the heat required to extract and process bitumen. Geothermal energy could be utilized to provide this necessary heat and has the potential to reduce both financial costs and environmental impacts of the oilsands industry. In order to determine the geothermal potential the details of the reservoir must be understood. Conventional hydrothermal reservoirs have been detected using geophysical techniques such as magnetotellurics (MT) which measures the electrical conductivity of the Earth. However, in Northern Alberta the geothermal gradient is relatively low, and heat must be extracted from deep inside the basement rocks using Engineered Geothermal Systems (EGS) and therefore an alternative exploration technique is required. MT can be useful in this context as it can detect fracture zones and regions of elevated porosity. MT data were recorded near Fort McMurray with the goal of determining the geothermal potential by understanding the crustal resistivity structure beneath the Athabasca Oilsands. The MT data are being used to locate targets of significance for geothermal exploration such as regions of low resistivity in the basement rocks which can relate to in situ fluids or fracture zones which can facilitate efficient heat extraction or het transport. A total of 93 stations were collected ~500m apart on two profiles stretching 30 and 20km respectively. Signals were recorded using Phoenix Geophysics V5-2000 systems over frequency bands from 1000 to 0.001 Hz, corresponding to depths of penetration approximately 50m to 50km. Groom-Bailey tensor decomposition and phase tensor analysis shows a well defined geoelectric strike direction that varied along the profile from N60°E to N45°E. Inversion of the data reveals the low resistivity sedimentary rocks of the Western Canadian Sedimentary Basin overlying a highly resistive Pre-Cambrian crystalline basement. The basement rocks have strong indications of being electrically anisotropic. Groom-Bailey and phase tensor azimuths are stable and consistent across both frequency and distance but display large phase tensor skew values (indicating 3D structure) and small induction vectors (indicating a lack of lateral structure). This type of anisotropy is unique because of its apparent widespread nature and the number of sites we have to constrain the anisotropic characteristics. These results can help to guide future geothermal development in Alberta as detailed information of the host rock resistivity structure can aid any EGS development.
SOIL VAPOR EXTRACTION TECHNOLOGY: REFERENCE HANDBOOK

EPA Science Inventory

Soil vapor extraction (SVE) systems are being used in Increasing numbers because of the many advantages these systems hold over other soil treatment technologies. SVE systems appear to be simple in design and operation, yet the fundamentals governing subsurface vapor transport ar...
IECEC '83; Proceedings of the Eighteenth Intersociety Energy Conversion Engineering Conference, Orlando, FL, August 21-26, 1983. Volume 1 - Thermal energy systems

NASA Astrophysics Data System (ADS)

Among the topics discussed are the nuclear fuel cycle, advanced nuclear reactor designs, developments in central status power reactors, space nuclear reactors, magnetohydrodynamic devices, thermionic devices, thermoelectric devices, geothermal systems, solar thermal energy conversion systems, ocean thermal energy conversion (OTEC) developments, and advanced energy conversion concepts. Among the specific questions covered under these topic headings are a design concept for an advanced light water breeder reactor, energy conversion in MW-sized space power systems, directionally solidified cermet electrodes for thermionic energy converters, boron-based high temperature thermoelectric materials, geothermal energy commercialization, solar Stirling cycle power conversion, and OTEC production of methanol. For individual items see A84-30027 to A84-30055
Geological Model of Supercritical Geothermal Reservoir on the Top of the Magma Chamber

NASA Astrophysics Data System (ADS)

Tsuchiya, N.

2017-12-01

We are conducting supercritical geothermal project, and deep drilling project named as "JBBP: Japan Beyond Brittle Project" The temperatures of geothermal fields operating in Japan range from 200 to 300 °C (average 250 °C), and the depths range from 1000 to 2000 m (average 1500 m). In conventional geothermal reservoirs, the mechanical behavior of the rocks is presumed to be brittle, and convection of the hydrothermal fluid through existing network is the main method of circulation in the reservoir. In order to minimize induced seismicity, a rock mass that is "beyond brittle" is one possible candidate, because the rock mechanics of "beyond brittle" material is one of plastic deformation rather than brittle failure. To understand the geological model of a supercritical geothermal reservoir, granite-porphyry system, which had been formed in subduction zone, was investigated as a natural analog of the supercritical geothermal energy system. Quartz veins, hydrothermal breccia veins, and glassy veins are observed in a granitic body. The glassy veins formed at 500-550 °C under lithostatic pressures, and then pressures dropped drastically. The solubility of silica also dropped, resulting in formation of quartz veins under a hydrostatic pressure regime. Connections between the lithostatic and hydrostatic pressure regimes were key to the formation of the hydrothermal breccia veins, and the granite-porphyry system provides useful information for creation of fracture clouds in supercritical geothermal reservoirs. A granite-porphyry system, associated with hydrothermal activity and mineralization, provides a suitable natural analog for studying a deep-seated geothermal reservoir where stockwork fracture systems are created in the presence of supercritical geothermal fluids. I describe fracture networks and their formation mechanisms using petrology and fluid inclusion studies in order to understand this "beyond brittle" supercritical geothermal reservoir, and a geological model for "Beyond Brittle" and "Supercritical" geothermal reservoir, which is located at the top of magma chamber of granite-porphyry system, will be revealed.
Composition inversion in mixtures of binary colloids and polymer

NASA Astrophysics Data System (ADS)

Zhang, Isla; Pinchaipat, Rattachai; Wilding, Nigel B.; Faers, Malcolm A.; Bartlett, Paul; Evans, Robert; Royall, C. Patrick

2018-05-01

Understanding the phase behaviour of mixtures continues to pose challenges, even for systems that might be considered "simple." Here, we consider a very simple mixture of two colloidal and one non-adsorbing polymer species, which can be simplified even further to a size-asymmetrical binary mixture, in which the effective colloid-colloid interactions depend on the polymer concentration. We show that this basic system exhibits surprisingly rich phase behaviour. In particular, we enquire whether such a system features only a liquid-vapor phase separation (as in one-component colloid-polymer mixtures) or whether, additionally, liquid-liquid demixing of two colloidal phases can occur. Particle-resolved experiments show demixing-like behaviour, but when combined with bespoke Monte Carlo simulations, this proves illusory, and we reveal that only a single liquid-vapor transition occurs. Progressive migration of the small particles to the liquid phase as the polymer concentration increases gives rise to composition inversion—a maximum in the large particle concentration in the liquid phase. Close to criticality, the density fluctuations are found to be dominated by the larger colloids.
Thermodynamics Analysis of Binary Plant Generating Power from Low-Temperature Geothermal Resource

NASA Astrophysics Data System (ADS)

Maksuwan, A.

2018-05-01

The purpose in this research was to predict tendency of increase Carnot efficiency of the binary plant generating power from low-temperature geothermal resource. Low-temperature geothermal resources or less, are usually exploited by means of binary-type energy conversion systems. The maximum efficiency is analyzed for electricity production of the binary plant generating power from low-temperature geothermal resource becomes important. By using model of the heat exchanger equivalent to a power plant together with the calculation of the combined heat and power (CHP) generation. The CHP was solved in detail with appropriate boundary originating an idea from the effect of temperature of source fluid inlet-outlet and cooling fluid supply. The Carnot efficiency from the CHP calculation was compared between condition of increase temperature of source fluid inlet-outlet and decrease temperature of cooling fluid supply. Result in this research show that the Carnot efficiency for binary plant generating power from low-temperature geothermal resource has tendency increase by decrease temperature of cooling fluid supply.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Calvin, Wendy

The Great Basin Center for Geothermal Energy (GBCGE or the Center) was established at the University of Nevada, Reno (UNR) in May 2000 to promote research and utilization of geothermal resources. The Center received funding through this grant to promote increased geothermal development in the Great Basin, with most of the funding used for peerreviewed research. Funding to the Center and work under the contract were initiated in March 2002, with supplemental funding in subsequent years. The Center monitored the research projects that were competitively awarded in a series of proposal calls between 2002 and 2007. Peer-reviewed research promoted identificationmore » and utilization of geothermal resources in Nevada. Projects used geology, geochemistry, geophysics, remote sensing, and the synthesis of multi-disciplinary information to produce new models of geothermal systems in the Western U.S. and worldwide. Funds were also used to support graduate student research and training. Part of the grant was used to support public outreach activities, including webpages, online maps and data resources, and informational workshops for stakeholders.« less

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shervais, John W.; Glen, Jonathan M.; Liberty, Lee M.

The Snake River volcanic province (SRP) overlies a thermal anomaly that extends deep into the mantle; it represents one of the highest heat flow provinces in North America. Our goals for this Phase 1 study are to: (1) adapt the methodology of Play Fairway Analysis for geothermal exploration to create a formal basis for its application to geothermal systems, (2) assemble relevant data for the SRP from publicly available and private sources, and (3) build a geothermal play fairway model for the SRP and identify the most promising plays, using software tools that are standard in the petroleum industry. Themore » success of play fairway analysis in geothermal exploration depends critically on defining a systematic methodology that is grounded in theory (as developed within the petroleum industry over the last two decades) and within the geologic and hydrologic framework of real geothermal systems. Our preliminary assessment of the data suggests that important undiscovered geothermal resources may be located in several areas of the SRP, including the western SRP (associated with buried lineaments defined by gravity or magnetic anomalies, and capped by extensive deposits of lacustrine sediment), at lineament intersections in the central SRP (along the Banbury-Hagerman trend NW of Twin Falls, and along the northern margin of the Mt Bennett Hills-Camas Prairie area), and along the margins of the eastern SRP. Additional high temperature resources are likely associated with rhyolite domes and crypto-domes in the eastern SRP, but are masked by shallow groundwater flow leading to low upper crustal heat flow values. These blind resources may be exploitable with existing deep drilling technology. Groundwater modeling planned for later phases of the PFA project will address whether temperatures at viable producing depths are sufficient to support electricity production.« less
Stable isotope fractionation at a glacial hydrothermal field: implications for biogeochemistry and biosignatures on Mars

NASA Astrophysics Data System (ADS)

Cousins, C.; Bowden, R.; Fogel, M.; Cockell, C.; Crawford, I.; Gunn, M.; Karlsson, M. T.; Thorsteinsson, T.

2012-12-01

Hydrothermal environments that arise through the interaction between volcanogenic heat and glacial ice are ideal sites for understanding microbial biogeochemical processes on Earth, and also potentially on Mars where similar volcano-cryosphere interactions are thought to have occurred in the past. The Kverkfjöll subglacial basaltic volcano in central Iceland is geographically isolated, with little influence from flora, fauna, and human activity. Major environmental inputs include geothermal heat, meltwater from ice and snow, and outgassing of CO2, H2S, and SO2. Large physiochemical gradients exist, from steaming fumaroles and boiling hydrothermal pools, to frozen geothermal ground and glacial ice. Stable isotope measurements of total organic carbon, total sulphur, and total nitrogen were coupled with metagenomic analysis of the residing microbial communities, with the aim to identify biogeochemical relationships and processes operating within the Kverkfjöll geothermal environment, and also to identify any isotopic biosignatures that could be preserved within geothermal sediments. This study focused on a variety of samples taken along a hot spring stream that fed into a large ice-confined geothermal lake. Samples analysed range from unconsolidated hot spring sediments, well-developed microbial mats, and dissolved sulphate from hot spring fluids. From the anoxic spring source, the stream water increases in dissolved oxygen, decreases in temperature, yet maintains a pH of ~4. The spring environment is dominated by dissolved sulphate (~2.3 mM), with lower levels of nitrate (~50 μM), phosphorus (~5μM), and ammonium (~1.5 μM). Stable S isotope analysis reveals a fractionation of ~3.2 ‰ between sediment sulphide (as pyrite; δ34S ~0‰), and dissolved water sulphate (δ34S ~3.2 ‰) consistently along the hot spring stream, indicating the presence of an active sulphur cycle, although not one dominated by sulphate reduction (e.g. very negative sulphide δ34S). This fractionation trend was absent within lake sediments, possibly due to a number of mixed sources feeding into the lake, in addition to the spring stream. δ13C in sediments becomes increasingly more negative going downstream, along with increasing removal of TOC. Microbial mats were largely similar with very positive C isotope ratios (δ13C -9.4 to -12.6 ‰) typical of sulphur oxidizing microbes. Bulk genomic DNA was extracted from sediments and mats in order to identify firstly the community composition via 454-pyrosequencing, and secondly the functional diversity within these physiochemically varied environments. This metagenomic data will be combined with stable isotope patterns to elucidate the metabolic potential of hydrothermal environments at Kverkfjöll, which can be used to infer potential biogeochemical pathways of signatures of such pathways on Mars in similar, past environments.
Coupling Flow & Transport Modeling with Electromagnetic Geophysics to Better Understand Crustal Permeability

NASA Astrophysics Data System (ADS)

Pepin, J.; Folsom, M.; Person, M. A.; Kelley, S.; Gomez-Velez, J. D.; Peacock, J.

2016-12-01

Over the last 30 years, considerable effort has focused on understanding the distribution of permeability within the earth's crust and its implications for flow and transport. The scarcity of direct observations makes the description of permeabilities beyond depths of about 3 km particularly challenging. Numerous studies have defined depth-decay relationships for basement permeability, while others note that it is too complex to be characterized by a general relationship. Hydrothermal modeling studies focusing on two geothermal systems within the tectonically active Rio Grande rift of New Mexico suggest that there may be laterally extensive regions of highly permeable (10-14 to 10-12 m2) basement rocks at depths ranging between 4 and 8 km. The NaCl groundwater signature, elevated fracture density, and secondary mineralization of fractured basement outcrops associated with these geothermal systems indicate that there may indeed be significant groundwater flow within the basement rocks of the rift. We hypothesize that there are extensive regions of highly permeable crystalline basement rocks at depths greater than 3 km within the Rio Grande rift. These fractured zones serve as large conduits for geothermal fluids before they ascend to shallow depths through gaps in overlying confining sediments or along faults. To test these hypotheses, we use a combination of geophysical observations and flow and transport modeling. We used electromagnetic geophysics (TEM & MT) to image resistivity in one of the hypothesized deep circulation geothermal systems near Truth or Consequences, NM. The resistivity dataset, in tandem with geochemical and thermal observations, is then used to calibrate a hydrothermal model of the system. This new calibration methodology has the potential to change the way researchers study crustal fluid flow and geothermal systems; thereby providing a tool to explore depths greater than 3 km where minimal data is available. In addition, it has the advantage of being scale-independent; meaning it can be applied to localized models just as well as continental-scale models.
Metagenomes from High-Temperature Chemotrophic Systems Reveal Geochemical Controls on Microbial Community Structure and Function

PubMed Central

Inskeep, William P.; Rusch, Douglas B.; Jay, Zackary J.; Herrgard, Markus J.; Kozubal, Mark A.; Richardson, Toby H.; Macur, Richard E.; Hamamura, Natsuko; Jennings, Ryan deM.; Fouke, Bruce W.; Reysenbach, Anna-Louise; Roberto, Frank; Young, Mark; Schwartz, Ariel; Boyd, Eric S.; Badger, Jonathan H.; Mathur, Eric J.; Ortmann, Alice C.; Bateson, Mary; Geesey, Gill; Frazier, Marvin

2010-01-01

The Yellowstone caldera contains the most numerous and diverse geothermal systems on Earth, yielding an extensive array of unique high-temperature environments that host a variety of deeply-rooted and understudied Archaea, Bacteria and Eukarya. The combination of extreme temperature and chemical conditions encountered in geothermal environments often results in considerably less microbial diversity than other terrestrial habitats and offers a tremendous opportunity for studying the structure and function of indigenous microbial communities and for establishing linkages between putative metabolisms and element cycling. Metagenome sequence (14–15,000 Sanger reads per site) was obtained for five high-temperature (>65°C) chemotrophic microbial communities sampled from geothermal springs (or pools) in Yellowstone National Park (YNP) that exhibit a wide range in geochemistry including pH, dissolved sulfide, dissolved oxygen and ferrous iron. Metagenome data revealed significant differences in the predominant phyla associated with each of these geochemical environments. Novel members of the Sulfolobales are dominant in low pH environments, while other Crenarchaeota including distantly-related Thermoproteales and Desulfurococcales populations dominate in suboxic sulfidic sediments. Several novel archaeal groups are well represented in an acidic (pH 3) Fe-oxyhydroxide mat, where a higher O2 influx is accompanied with an increase in archaeal diversity. The presence or absence of genes and pathways important in S oxidation-reduction, H2-oxidation, and aerobic respiration (terminal oxidation) provide insight regarding the metabolic strategies of indigenous organisms present in geothermal systems. Multiple-pathway and protein-specific functional analysis of metagenome sequence data corroborated results from phylogenetic analyses and clearly demonstrate major differences in metabolic potential across sites. The distribution of functional genes involved in electron transport is consistent with the hypothesis that geochemical parameters (e.g., pH, sulfide, Fe, O2) control microbial community structure and function in YNP geothermal springs. PMID:20333304
Performance, Cost, and Financial Parameters of Geothermal District Heating Systems for Market Penetration Modeling under Various Scenarios

DOE Office of Scientific and Technical Information (OSTI.GOV)

Beckers, Koenraad J; Young, Katherine R

Geothermal district heating (GDH) systems have limited penetration in the U.S., with an estimated installed capacity of only 100 MWth for a total of 21 sites. We see higher deployment in other regions, for example, in Europe with an installed capacity of more than 4,700 MWth for 257 GDH sites. The U.S. Department of Energy Geothermal Vision (GeoVision) Study is currently looking at the potential to increase the deployment in the U.S. and to understand the impact of this increased deployment. This paper reviews 31 performance, cost, and financial parameters as input for numerical simulations describing GDH system deployment inmore » support of the GeoVision effort. The focus is on GDH systems using hydrothermal and Enhanced Geothermal System resources in the U.S.; ground-source heat pumps and heat-to-electricity conversion technology were excluded. Parameters investigated include 1) capital and operation and maintenance costs for both subsurface and surface equipment; 2) performance factors such as resource recovery factors, well flow rates, and system efficiencies; and 3) financial parameters such as inflation, interest, and tax rates. Current values as well as potential future improved values under various scenarios are presented. Sources of data considered include academic and popular literature, software tools such as GETEM and GEOPHIRES, industry interviews, and analysis conducted by other task forces for the GeoVision Study, e.g., on the drilling costs and reservoir performance.« less
Thermally driven electrokinetic energy conversion with liquid water microjets

NASA Astrophysics Data System (ADS)

Lam, Royce K.; Gamlieli, Zach; Harris, Stephen J.; Saykally, Richard J.

2015-11-01

A goal of current energy research is to design systems and devices that can efficiently exploit waste heat and utilize solar or geothermal heat energy for electrical power generation. We demonstrate a novel technique exploiting water's large coefficient of thermal expansion, wherein modest thermal gradients produce the requisite high pressure for driving fast-flowing liquid water microjets, which can effect the direct conversion of the kinetic energy into electricity and gaseous hydrogen. Waste heat in thermoelectric generating plants and combustion engines, as well as solar and geothermal energy could be used to drive these systems.
Geothermal energy resources of wadi Al-Lith, Saudi Arabia

NASA Astrophysics Data System (ADS)

Lashin, A.; Chandrasekharam, D.; Al Arifi, N.; Al Bassam, A.; Varun, C.

2014-09-01

The entire western Arabian shield is the domain of both hydrothermal and enhanced geothermal systems associated with volcanic centres (Harrats) and high heat generating granites. The most prominent sites of hydrothermal systems are located around Al-Lith and Jizan. The hydrothermal system in Al Lith is controlled by high heat generating (∼11 μW/m3) post orogenic granites. The high heat flow value of >80 mW/m2 across Al-Lith coast is due to such granite intrusives, presence of dike swarms that intrude into the granites as well as position of Moho at shallow level. Although the thermal waters are chloride rich, Red Sea involvement is not observed. Long residence time and water rock interaction with granites are the main processes responsible for chloride enrichment in the thermal waters. Oxygen isotope shift indicates presence of high temperature geothermal system in the area. The tritium values indicate that the circulating waters are >75 years old.
Development of Genetic Occurrence Models for Geothermal Prospecting

NASA Astrophysics Data System (ADS)

Walker, J. D.; Sabin, A.; Unruh, J.; Monastero, F. C.; Combs, J.

2007-12-01

Exploration for utility-grade geothermal resources has mostly relied on identifying obvious surface manifestations of possible geothermal activity, e.g., locating and working near steaming ground or hot springs. This approach has lead to the development of over 130 resources worldwide, but geothermal exploration done in this manner is akin to locating hydrocarbon plays by searching for oil seeps. Confining exploration to areas with such features will clearly not discover a blind resource, that is, one that does not have surface expression. Blind resources, however, constitute the vast majority of hydrocarbon plays; this may be the case for geothermal resources as well. We propose a geothermal exploration strategy for finding blind systems that is based on an understanding of the geologic processes that transfer heat from the mantle to the upper crust and foster the conditions for hydrothermal circulation or enhanced geothermal exploration. The strategy employs a genetically based screening protocol to assess potential geothermal sites. The approach starts at the plate boundary scale and progressively focuses in on the scale of a producing electrical-grade field. Any active margin or hot spot is a potential location for geothermal resources. Although Quaternary igneous activity provides a clear indication of active advection of hot material into the upper crust, it is not sufficient to guarantee a potential utility-grade resource. Active faulting and/or evidence of high strain rates appear to be the critical features associated with areas of utility-grade geothermal potential. This is because deformation on its own can advect sufficient heat into the upper crust to create conditions favorable for geothermal exploitation. In addition, active deformation is required to demonstrate that open pathways for circulation of geothermal fluids are present and/or can be maintained. The last step in the screening protocol is to identify any evidence of geothermal activity, including high heat flow, anomalous temperature water wells, high-temperature indications from aqueous geothermometry and geochemistry, Pliocene or younger ages from low-temperature thermochronometers, as well as more obvious factors such as geysers and fumaroles (which by definition will be missing for blind resources). Our occurrence-model strategy inverts the current approach that relies first on obvious evidence of geothermal activity. We evaluated our approach by retrospectively applying the protocol to the characteristics of producing geothermal fields, and in all cases, known resource areas fit the parameters identified from a genetic perspective.
Geothermally Coupled Well-Based Compressed Air Energy Storage

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davidson, Casie L.; Bearden, Mark D.; Horner, Jacob A.

2015-12-20

Previous work by McGrail et al. (2013, 2015) has evaluated the possibility of pairing compressed air energy storage with geothermal resources in lieu of a fossil-fired power generation component, and suggests that such applications may be cost competitive where geology is favorable to siting both the geothermal and CAES components of such a system. Those studies also note that the collocation of subsurface resources that meet both sets of requirements are difficult to find in areas that also offer infrastructure and near- to mid-term market demand for energy storage. This study examines a novel application for the compressed air storagemore » portion of the project by evaluating the potential to store compressed air in disused wells by amending well casings to serve as subsurface pressure vessels. Because the wells themselves would function in lieu of a geologic storage reservoir for the CAES element of the project, siting could focus on locations with suitable geothermal resources, as long as there was also existing wellfield infrastructure that could be repurposed for air storage. Existing wellfields abound in the United States, and with current low energy prices, many recently productive fields are now shut in. Should energy prices remain stagnant, these idle fields will be prime candidates for decommissioning unless they can be transitioned to other uses, such as redevelopment for energy storage. In addition to the nation’s ubiquitous oil and gas fields, geothermal fields, because of their phased production lifetimes, also may offer many abandoned wellbores that could be used for other purposes, often near currently productive geothermal resources. These existing fields offer an opportunity to decrease exploration and development uncertainty by leveraging data developed during prior field characterization, drilling, and production. They may also offer lower-cost deployment options for hybrid geothermal systems via redevelopment of existing well-field infrastructure. This project assessed the technical and economic feasibility of implementing geothermally coupled well-based CAES for grid-scale energy storage. Based on an evaluation of design specifications for a range of casing grades common in U.S. oil and gas fields, a 5-MW CAES project could be supported by twenty to twenty-five 5,000-foot, 7-inch wells using lower-grade casing, and as few as eight such wells for higher-end casing grades. Using this information, along with data on geothermal resources, well density, and potential future markets for energy storage systems, The Geysers geothermal field was selected to parameterize a case study to evaluate the potential match between the proven geothermal resource present at The Geysers and the field’s existing well infrastructure. Based on calculated wellbore compressed air mass, the study shows that a single average geothermal production well could provide enough geothermal energy to support a 15.4-MW (gross) power generation facility using 34 to 35 geothermal wells repurposed for compressed air storage, resulting in a simplified levelized cost of electricity (sLCOE) estimated at 11.2 ¢/kWh (Table S.1). Accounting for the power loss to the geothermal power project associated with diverting geothermal resources for air heating results in a net 2-MW decrease in generation capacity, increasing the CAES project’s sLCOE by 1.8 ¢/kWh.« less
DOE Office of Scientific and Technical Information (OSTI.GOV)

Davidson, C L; Bearden, Mark D; Horner, Jacob A

Previous work by McGrail et al. (2013, 2015) has evaluated the possibility of pairing compressed air energy storage with geothermal resources in lieu of a fossil-fired power generation component, and suggests that such applications may be cost competitive where geology is favorable to siting both the geothermal and CAES components of such a system. Those studies also note that the collocation of subsurface resources that meet both sets of requirements are difficult to find in areas that also offer infrastructure and near- to mid-term market demand for energy storage. This study examines a novel application for the compressed air storagemore » portion of the project by evaluating the potential to store compressed air in disused wells by amending well casings to serve as subsurface pressure vessels. Because the wells themselves would function in lieu of a geologic storage reservoir for the CAES element of the project, siting could focus on locations with suitable geothermal resources, as long as there was also existing wellfield infrastructure that could be repurposed for air storage. Existing wellfields abound in the United States, and with current low energy prices, many recently productive fields are now shut in. Should energy prices remain stagnant, these idle fields will be prime candidates for decommissioning unless they can be transitioned to other uses, such as redevelopment for energy storage. In addition to the nation’s ubiquitous oil and gas fields, geothermal fields, because of their phased production lifetimes, also may offer many abandoned wellbores that could be used for other purposes, often near currently productive geothermal resources. These existing fields offer an opportunity to decrease exploration and development uncertainty by leveraging data developed during prior field characterization, drilling, and production. They may also offer lower-cost deployment options for hybrid geothermal systems via redevelopment of existing well-field infrastructure. This project assessed the technical and economic feasibility of implementing geothermally coupled well-based CAES for grid-scale energy storage. Based on an evaluation of design specifications for a range of casing grades common in U.S. oil and gas fields, a 5-MW CAES project could be supported by twenty to twenty-five 5,000-foot, 7-inch wells using lower-grade casing, and as few as eight such wells for higher-end casing grades. Using this information, along with data on geothermal resources, well density, and potential future markets for energy storage systems, The Geysers geothermal field was selected to parameterize a case study to evaluate the potential match between the proven geothermal resource present at The Geysers and the field’s existing well infrastructure. Based on calculated wellbore compressed air mass, the study shows that a single average geothermal production well could provide enough geothermal energy to support a 15.4-MW (gross) power generation facility using 34 to 35 geothermal wells repurposed for compressed air storage, resulting in a simplified levelized cost of electricity (sLCOE) estimated at 11.2 ¢/kWh (Table S.1). Accounting for the power loss to the geothermal power project associated with diverting geothermal resources for air heating results in a net 2-MW decrease in generation capacity, increasing the CAES project’s sLCOE by 1.8 ¢/kWh.« less
HIGH-TEMPERATURE GEOTHERMAL RESOURCES IN HYDROTHERMAL CONVECTION SYSTEMS IN THE UNITED STATES.

USGS Publications Warehouse

Nathenson, Manuel

1983-01-01

The calculation of high-temperature geothermal resources ( greater than 150 degree C) in the United States has been done by estimating the temperature, area, and thickness of each identified system. These data, along with a general model for recoverability of geothermal energy and a calculation that takes account of the conversion of thermal energy to electricity, yielded an estimate of 23,000 MW//e for 30 years. The undiscovered component was estimated based on multipliers of the identified resource as either 72,000 or 127,000 MW//e for 30 years depending on the model chosen for the distribution of undiscovered energy as a function of temperature.
Thermally driven electrokinetic energy conversion with liquid water microjets

DOE PAGES

Lam, Royce K.; Gamlieli, Zach; Harris, Stephen J.; ...

2015-11-01

One goal of current energy research is to design systems and devices that can efficiently exploit waste heat and utilize solar or geothermal heat energy for electrical power generation. We demonstrate a novel technique exploiting water's large coefficient of thermal expansion, wherein modest thermal gradients produce the requisite high pressure for driving fast-flowing liquid water microjets, which can effect the direct conversion of the kinetic energy into electricity and gaseous hydrogen. Waste heat in thermoelectric generating plants and combustion engines, as well as solar and geothermal energy could be used to drive these systems.
Using Facilities And Potential Of Geothermal Resources In The Canakkale Province - NW Turkey

NASA Astrophysics Data System (ADS)

Deniz, Ozan; Acar Deniz, Zahide

2016-04-01

Turkey, due to its geological location, has a rich potential in point of geothermal resources. Çanakkale province is located northwestern (NW) part of Turkey and it has important geothermal fields in terms of geothermal energy potential. Geothermal resources reach to the surface both effects of past volcanic activity and extensions of fault zones associated with complex tectonic systems in the region. The aim of this study is to summarize hydrogeochemical characteristics, using facilities and potential of hot springs and spas located in the Çanakkale province. There are 13 geothermal fields in the region and the surface temperatures of hot springs are ranging between 28 centigrade degree and 175 centigrade degree. Hydrogeochemical compositions of thermal water display variable chemical compositions. Na, Ca, SO4, HCO3 and Cl are the dominant ions in these waters. Thermal waters of Tuzla and Kestanbol geothermal fields which is located the near coastal area can be noted NaCl type. Because these two geothermal waters have high TDS values, scaling problems are seen around the hot springs and pipelines. Geothermal waters in the province are meteoric origin according to oxygen-18, deuterium and tritium isotopes data. Long underground residence times of these waters and its temperatures have caused both more water - rock interaction and low tritium values. Geothermal energy is utilized in many areas in Turkey today. It is generally used for space heating, balneotherapy and electricity generation. Explorations of geothermal resources and investments in geothermal energy sector have risen rapidly in the recent years particularly in western Turkey. High-temperature geothermal fields are generally located in this region related to the Aegean Graben System and the North Anotalian Fault Zone. All geothermal power plants in Turkey are located in this region. Considering the Çanakkale province, most geothermal fields are suitable for multipurpose usage but many of them have been still used only for spa tourism. Residential heating and greenhouse activities do not exist in the region yet. However, the only geothermal power plant which is settled in NW Turkey is located in Tuzla geothermal field (7.5 MW capacity). This area is both the most high-temperature area in the region and one of the most important geothermal fields in Turkey. Very little thermal centers in Turkey have thermal water potential of the coastal area like Çanakkale province. Climatic features of this area allows both thermal and sea tourism applications in all season of a year such as open-air curing, heliotherapy and thalassotherapy. Çanakkale province is located in "Troy North Aegean Culture and Thermal Tourism Development Zone". This area is being planned within the framework of health, thermal and rural tourism by the Republic of Turkey Ministry of Culture and Tourism. Keywords: Geothermal, Hydrogeochemistry, Çanakkale, Turkey
Sensitivity analysis of coupled processes and parameters on the performance of enhanced geothermal systems.

PubMed

Pandey, S N; Vishal, Vikram

2017-12-06

3-D modeling of coupled thermo-hydro-mechanical (THM) processes in enhanced geothermal systems using the control volume finite element code was done. In a first, a comparative analysis on the effects of coupled processes, operational parameters and reservoir parameters on heat extraction was conducted. We found that significant temperature drop and fluid overpressure occurred inside the reservoirs/fracture that affected the transport behavior of the fracture. The spatio-temporal variations of fracture aperture greatly impacted the thermal drawdown and consequently the net energy output. The results showed that maximum aperture evolution occurred near the injection zone instead of the production zone. Opening of the fracture reduced the injection pressure required to circulate a fixed mass of water. The thermal breakthrough and heat extraction strongly depend on the injection mass flow rate, well distances, reservoir permeability and geothermal gradients. High permeability caused higher water loss, leading to reduced heat extraction. From the results of TH vs THM process simulations, we conclude that appropriate coupling is vital and can impact the estimates of net heat extraction. This study can help in identifying the critical operational parameters, and process optimization for enhanced energy extraction from a geothermal system.
High-resolution chemical composition of geothermal scalings from Hungary: Preliminary results

NASA Astrophysics Data System (ADS)

Boch, Ronny; Dietzel, Martin; Deák, József; Leis, Albrecht; Mindszenty, Andrea; Demeny, Attila

2015-04-01

Geothermal fluids originating from several hundreds to thousands meters depth mostly hold a high potential for secondary mineral precipitation (scaling) due to high total dissolved solid contents at elevated temperature and pressure conditions. The precipitation of e.g. carbonates, sulfates, sulfides, and silica has shown to cause severe problems in geothermal heat and electric power production, when clogging of drill-holes, downhole pumps, pipes and heat exchangers occurs (e.g. deep geothermal doublet systems). Ongoing scaling reduces the efficiency in energy extraction and might even question the abandonment of installations in worst cases. In an attempt to study scaling processes both temporally and spatially we collected mineral precipitates from selected sites in Hungary (Bükfürdo, Szechenyi, Szentes, Igal, Hajduszoboszlo). The samples of up to 8 cm thickness were recovered from different positions of the geothermal systems and precipitated from waters of various temperatures (40-120 °C) and variable overall chemical composition. Most of these scalings show fine lamination patterns representing mineral deposition from weeks up to 45 years at our study sites. Solid-fluid interaction over time captured in the samples are investigated applying high-resolution analytical techniques such as laser-ablation mass-spectrometry and electron microprobe, micromill-sampling for stable isotope analysis, and micro-XRD combined with hydrogeochemical modeling. A detailed investigation of the processes determining the formation and growth of precipitates can help to elucidate the short-term versus long-term geothermal performance with regard to anthropogenic and natural reservoir and production dynamics. Changes in fluid chemistry, temperature, pressure, pH, degassing rate (CO2) and flow rate are reflected by the mineralogical, chemical and isotopic composition of the precipitates. Consequently, this high-resolution approach is intended as a contribution to decipher the environmental conditions during the formation of the investigated scalings and to increase our knowledge on retarding and preventive measures of scaling for geothermal applications.
Highly vibrationally excited CO generated in a low-temperature chemical reaction between carbon vapor and molecular oxygen

NASA Astrophysics Data System (ADS)

Jans, E.; Frederickson, K.; Yurkovich, M.; Musci, B.; Rich, J. W.; Adamovich, I. V.

2016-08-01

A chemical flow reactor is used to study the vibrational population distribution of CO produced by a reaction between carbon vapor generated in an arc discharge and molecular oxygen. The results demonstrate formation of highly vibrationally excited CO, up to vibrational level v = 14, at low temperatures, T = 400-450 K, with population inversion at v = 4-7, in a collision-dominated environment, 15-20 Torr. The average vibrational energy per CO molecule formed by the reaction is 0.6-1.2 eV/molecule, which corresponds to 10-20% of reaction enthalpy. The results show feasibility of development of a new CO chemical laser using carbon vapor and oxygen as reactants.
Influence of biofilm formation on corrosion and scaling in geothermal plants

NASA Astrophysics Data System (ADS)

Kleyböcker, Anne; Lerm, Stephanie; Monika, Kasina; Tobias, Lienen; Florian, Eichinger; Andrea, Seibt; Markus, Wolfgramm; Hilke, Würdemann

2017-04-01

Process failures may occur due to corrosion and scaling processes in open loop geothermal systems. Especially after heat extraction, sulfate reducing bacteria (SRB) contribute to corrosion processes due to a more favorable temperature for their growth. In biofilms containing FeS scales, corrosion processes are enhanced. Furthermore, scales can lead to reduced pipe profiles, to a diminished heat transfer and a decrease in the wellbore injectivity. Inhibitors are frequently applied to minimize scaling in technical systems. A prerequisite for the application of inhibitors in geothermal plants located in the Molasse basin is their degradability under reservoir conditions, e. g. in a reduced environment. In order to determine the effects of scale-inhibitors on the subsurface and microbial processes, laboratory experiments were performed focusing on the microbial inhibitor degradation. First results indicate that the inhibitor degradation under anaerobic conditions is possible. Besides the inhibitor application also other techniques are investigated to economically reduce corrosion and scaling in geothermal plants. In a mobile bypass system, the influence of biofilm formation on corrosion and scaling was investigated. The bypass system was tested at a geothermal heat store in the North German Basin. The plant is operated with highly saline fluid (salinity 130 g/L) and known to be affected by SRB. The SRB contributed to corrosion damages especially at the pump in the well on the cold side. Heat shocks were successfully used in the bypass system to reduce biofilm formation as well as corrosion and scaling processes.
Radiator Enhanced Geothermal System - A Revolutionary Method for Extracting Geothermal Energy

NASA Astrophysics Data System (ADS)

Karimi, S.; Marsh, B. D.; Hilpert, M.

2017-12-01

A new method of extracting geothermal energy, the Radiator Enhanced Geothermal System (RAD-EGS) has been developed. RAD-EGS attempts to mimic natural hydrothermal systems by 1) generating a vertical vane of artificially produced high porosity/permeability material deep in a hot sedimentary aquifer, 2) injecting water at surface temperatures to the bottom of the vane, where the rock is the hottest, 3) extracting super-heated water at the top of the vane. The novel RAD-EGS differs greatly from the currently available Enhanced Geothermal Systems in vane orientation, determined in the governing local crustal stress field by Shmax and Sl (meaning it is vertical), and in the vane location in a hot sedimentary aquifer, which naturally increases the longevity of the system. In this study, we explore several parameters regimes affecting the water temperature in the extraction well, keeping in mind that the minimum temperature of the extracted water has to be 150 °C in order for a geothermal system to be commercially viable. We used the COMSOL finite element package to simulate coupled heat and fluid transfer within the RAD-EGS model. The following geologic layers from top to bottom are accounted for in the model: i) confining upper layer, ii) hot sedimentary aquifer, and iii) underlying basement rock. The vane is placed vertically within the sedimentary aquifer. An injection well and an extraction well are also included in the simulation. We tested the model for a wide range of various parameters including background heat flux, thickness of geologic layers, geometric properties of the vane, diameter and location of the wells, fluid flow within the wells, regional hydraulic gradient, and permeability and porosity of the layers. The results show that among the aforementioned parameters, background heat flux and the depth of vane emplacement are highly significant in determining the level of commercial viability of the geothermal system. These results indicate that for the terrains with relatively high background heat flux or for vanes located in relatively deep layers, the RAD-EGS can produce economic geothermal energy for more than 40 years. Moreover, these simulations show that the geothermal vane design with the injection well at the bottom and production well at the top of the vane greatly contributes to the longevity of the system.
G.POT: a method for the assessment and mapping of the near-surface geothermal potential

NASA Astrophysics Data System (ADS)

Casasso, Alessandro; Sethi, Rajandrea

2017-04-01

Shallow geothermal systems are widely recognised as a valuable technology for the heating and cooling of buildings. The most adopted technology is the Borehole Heat Exchanger (BHE), since it can be installed almost everywhere. However, the economic viability of BHEs depends on the thermal load that can be efficiently exchanged with the ground, i.e. the near-surface geothermal potential. We present the G.POT (Geothermal POTential) method for the assessment of near-surface geothermal potential as a function of the thermal conductivity and capacity of the ground, of its initial temperature, of the thermal resistance of the BHE and of the duration of the sinusoidal thermal load cycle, which reproduces the typical pattern of a thermal load during a heating or a cooling season. The function was calibrated from the results of numerical heat transfer simulations, performed varying the values of the aforementioned parameters over broad ranges. G.POT is a simple mathematical tool which can be easily implemented for the large-scale assessment and mapping of the near-surface geothermal potential for heating or cooling purpose. An example of its application is also shown, and advice is provided on the processing of input parameters. References A. Casasso, R. Sethi, G.POT: A quantitative method for the assessment and mapping of the shallow geothermal potential, Energy 106 (2016) 765-773. A. Casasso, R. Sethi, Assessment and mapping of the shallow geothermal potential in the province of Cuneo (Piedmont, NW Italy), Renewable Energy 102, Part B (2017) 306-315.
Origin and potential geothermal significance of China Hat and other late Pleistocene topaz rhyolite lava domes of the Blackfoot Volcanic Field, SE Idaho

NASA Astrophysics Data System (ADS)

McCurry, M. O.; Pearson, D. M.; Welhan, J. A.; Kobs-Nawotniak, S. E.; Fisher, M. A.

2014-12-01

The Snake River Plain and neighboring regions are well known for their high heat flow and robust Neogene-Quaternary tectonic and magmatic activity. Interestingly, however, there are comparatively few surficial manifestations of geothermal activity. This study is part of a renewed examination of this region as a possible hidden or blind geothermal resource. We present a testable, integrated volcanological, petrogenetic, tectonic and hydrothermal conceptual model for 57 ka China Hat and cogenetic topaz rhyolite lava domes of the Blackfoot Volcanic Field. This field is well suited for analysis as a blind resource because of its distinctive combination of (1) young bimodal volcanism, petrogenetic evidence of shallow magma storage and evolution, presence of coeval extension, voluminous travertine deposits, and C- and He-isotopic evidence of active magma degassing; (2) a paucity of hot springs or other obvious indicators of a geothermal resource in the immediate vicinity of the lava domes; and (3) proximity to a region of high crustal heat flow, high-T geothermal fluids at 2.5-5 km depth and micro-seismicity characterized by its swarming nature. Eruptions of both basalt and rhyolite commonly evolve from minor phreatomagmatic to effusive. In our model, transport of both magmatic and possible deep crustal aqueous fluids may be controlled by preexisting crustal structures, including west-dipping thrust faults. Geochemical evolution of rhyolite magma is dominated by mid- to upper-crustal fractional crystallization (with pre-eruption storage and phenocryst formation at ~14 km). Approximately 1.2 km3 of topaz rhyolite have been erupted since 1.4 Ma, yielding an average eruption rate of 0.8 km3/m.y. Given reasonable assumptions of magma cumulate formation and eruption rates, and initial and final volatile concentrations, we infer average H2O and CO2 volatile fluxes from the rhyolite source region of ~2MT/year and 340 T/day, respectively. Lithium flux may be comparable to CO2.

Characterization of Hydrologic and Thermal Properties at Brady Geothermal Field, NV

NASA Astrophysics Data System (ADS)

Patterson, J.; Cardiff, M. A.; Lim, D.; Coleman, T.; Wang, H. F.; Feigl, K. L.

2017-12-01

Understanding and predicting the temperature evolution of geothermal reservoirs is a primary focus for geothermal power plant operators ensuring continued financial sustainability of the resource. Characterization of reservoir properties - such as thermal diffusivity and hydraulic conductivity - facilitates modeling efforts to develop a better understanding of temperature evolution. As part of the integrated "PoroTomo" experiment, borehole pressure measurements were collected in three monitoring wells of various depths under varying operational conditions at the Brady Geothermal Field near Reno, NV. During normal operational conditions, a vertical profile of borehole temperature to 330 m depth was collected using distributed temperature sensing (DTS) for a period of 5 days. Borehole pressure data indicates 2D flow and shows rapid responses to changes in pumping /injection rates, likely indicating fault-dominated flow. The temperature data show that borehole temperature recovery following cold water slug injection is variable with depth. Late time vertical temperature profiles show the borehole following a shallow geotherm to a depth of approximately 275 meters, below which the temperature declines until a depth of approximately 320 meters, with a stable zone of cold water forming below this, possibly indicating production-related thermal drawdown. A validated heat transfer model is used in conjunction with the temperature data to determine depth-dependent reservoir thermal properties. Hydraulic reservoir properties are determined through inversion of the collected pressure data using MODFLOW. These estimated thermal and hydraulic properties are synthesized with existing structural and stratigraphic datasets at Brady. The work presented herein was funded in part by the Office of Energy Efficiency and Renewable Energy (EERE), U.S. Department of Energy, under Award Number DE-EE0006760.
The Radiator-Enhanced Geothermal System

NASA Astrophysics Data System (ADS)

Hilpert, M.; Marsh, B. D.; Geiser, P.

2015-12-01

Standard Enhanced Geothermal Systems (EGS) have repeatedly been hobbled by the inability of rock to conductively transfer heat at rates sufficient to re-supply heat extracted convectively via artificially made fracture systems. At the root of this imbalance is the basic magnitude of thermal diffusivity for most rocks, which severely hampers heat flow once the cooled halos about fractures reach ~0.1 m or greater. This inefficiency is exacerbated by the standard EGS design of mainly horizontally constructed fracture systems with inflow and outflow access at the margins of the fracture network. We introduced an alternative system whereby the heat exchanger mimics a conventional radiator in an internal combustion engine, which we call a Radiator-EGS (i.e., RAD-EGS). The heat exchanger is built vertically with cool water entering the base and hot water extracted at the top. The RAD-EGS itself consists of a family of vertical vanes produced through sequential horizontal drilling and permeability stimulation through propellant fracking. The manufactured fracture zones share the orientation of the natural transmissive fracture system. As below about 700 m, S1 is vertical and the average strike of transmissive fractures parallels SHmax, creating vertical fractures that include S1 and SHmax requires drilling stacked laterals parallel to SHmax. The RAD-EGS is also based on the observation that the longevity of natural hydrothermal systems depends on thermal recharge through heat convection but not heat conduction. In this paper, we present numerical simulations that examine the effects of the depths of the injector and extraction wells, vane size, coolant flow rate, the natural crustal geothermal gradient, and natural regional background flow on geothermal energy extraction.
Snake River Plain Play Fairway Analysis - Phase 1 Report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shervais, John W.; Glen, Jonathan M.; Liberty, Lee M.

2015-09-02

The Snake River volcanic province (SRP) overlies a thermal anomaly that extends deep into the mantle; it represents one of the highest heat flow provinces in North America. Our goals for this Phase 1 study are to: (1) adapt the methodology of Play Fairway Analysis for geothermal exploration to create a formal basis for its application to geothermal systems, (2) assemble relevant data for the SRP from publicly available and private sources, and (3) build a geothermal play fairway model for the SRP and identify the most promising plays, using software tools that are standard in the petroleum industry. Themore » success of play fairway analysis in geothermal exploration depends critically on defining a systematic methodology that is grounded in theory (as developed within the petroleum industry over the last two decades) and within the geologic and hydrologic framework of real geothermal systems. Our preliminary assessment of the data suggests that important undiscovered geothermal resources may be located in several areas of the SRP, including the western SRP (associated with buried lineaments defined by gravity or magnetic anomalies, and capped by extensive deposits of lacustrine sediment), at lineament intersections in the central SRP (along the Banbury-Hagerman trend NW of Twin Falls, and along the northern margin of the Mt Bennett Hills-Camas Prairie area), and along the margins of the eastern SRP. Additional high temperature resources are likely associated with rhyolite domes and crypto-domes in the eastern SRP, but are masked by shallow groundwater flow leading to low upper crustal heat flow values. These blind resources may be exploitable with existing deep drilling technology. Groundwater modeling planned for later phases of the PFA project will address whether temperatures at viable producing depths are sufficient to support electricity production.« less
Appendices of an appraisal for the use of geothermal energy in state-owned buildings in Colorado. Section D. Durango

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meyer, R.T.; Coe, B.A.; Dick, J.D.

1981-01-01

Four state-owned building complexes ahve been evaluated within the city of Durango: The State Fish Hatchery, Fort Lewis College, new State Highway Department Building near the Bodo Industrial Park, and the National Guard Building. Three of the state facilities in Durango are evaluated for geothermal systems on thea ssumption of taking geothermal water from a trunk-line originating at the area northof Durango: State Fish Hatchery, Fort Lewis College and new State Highway Department Building. The National Guard Building is evaluated on the basis of a water-to-air heat pump, with warm water derived from a hypothetical shallow aquifer immediately below themore » building site. Two geothermal options were separately evaluated for Fort Lewis College: a central heat exchanger system for delivery of 145/sup 0/F heating water to the campus buildings and a central heat pump system for boosting the heating water to 200/sup 0/F prior to delivery to the buildings; both systems require the installation of a distribution piping network for the entire campus area. Retrofit engineering for the State Fish Hatchery provides for the installation of a small scale central distribution piping system to the several buildings, a central heat excanger coupled to the geothermal trunk line, and the use of various fan coil and unit heaters for space heating. An option is provided for discharge-mixing the geothermal water into the fish ponds and runs in order to raise the hatchery water temperature a couple degrees for increasing fish production and yield. The heating system for the new State Highway Department Building is redesigned to replace the natural-gas-fired forced-air furnaces with a heat exchanger, hot water fan coils and unit heaters.« less
Peeking Beneath the Caldera: Communicating Subsurface Knowledge of Newberry Volcano

NASA Astrophysics Data System (ADS)

Mark-Moser, M.; Rose, K.; Schultz, J.; Cameron, E.

2016-12-01

"Imaging the Subsurface: Enhanced Geothermal Systems and Exploring Beneath Newberry Volcano" is an interactive website that presents a three-dimensional subsurface model of Newberry Volcano developed at National Energy Technology Laboratory (NETL). Created using the Story Maps application by ArcGIS Online, this format's dynamic capabilities provide the user the opportunity for multimedia engagement with the datasets and information used to build the subsurface model. This website allows for an interactive experience that the user dictates, including interactive maps, instructive videos and video capture of the subsurface model, and linked information throughout the text. This Story Map offers a general background on the technology of enhanced geothermal systems and the geologic and development history of Newberry Volcano before presenting NETL's modeling efforts that support the installation of enhanced geothermal systems. The model is driven by multiple geologic and geophysical datasets to compare and contrast results which allow for the targeting of potential EGS sites and the reduction of subsurface uncertainty. This Story Map aims to communicate to a broad audience, and provides a platform to effectively introduce the model to researchers and stakeholders.
Thermodynamic study of (anthracene + benzo[a]pyrene) solid mixtures

PubMed Central

Rice, James W.; Suuberg, Eric M.

2010-01-01

To characterize better the thermodynamic behavior of a binary polycyclic aromatic hydrocarbon mixture, thermochemical and vapor pressure experiments were used to examine the phase behavior of the {anthracene (1) + benzo[a]pyrene (2)} system. A solid-liquid phase diagram was mapped for the mixture. A eutectic point occurs at x1 = 0.26. The eutectic mixture is an amorphous solid that lacks organized crystal structure and melts between T = (414 and 420) K. For mixtures that contain 0.10 < x1 < 0.90, the enthalpy of fusion is dominated by that of the eutectic. Solid-vapor equilibrium studies show that mixtures of anthracene and benzo[a]pyrene at x1 < 0.10 sublime at the vapor pressure of pure benzo[a]pyrene. These results suggest that the solid-vapor equilibrium of benzo[a]pyrene is not significantly influenced by moderate levels of anthracene in the crystal structure. PMID:20814451
Fault rock mineralogy and fluid flow in the Coso Geothermal Field, CA

NASA Astrophysics Data System (ADS)

Davatzes, N. C.; Hickman, S. H.

2005-12-01

The minerals that comprise fault rock, their grain shapes, and packing geometry are important controls on fault zone properties such as permeability, frictional strength, and slip behavior. In this study we examine the role of mineralogy and deformation microstructures on fluid flow in a fault-hosted, fracture-dominated geothermal system contained in granitic rocks in the Coso Geothermal Field, CA. Initial examination of the mineralogy and microstructure of fault rock obtained from core and surface outcrops reveals three fault rock types. (1) Fault rock consisting of kaolinite and amorphous silica that contains large connected pores, dilatant brittle fractures, and dissolution textures. (2) Fault rock consisting of foliated layers of chlorite and illite-smectite separated by slip surfaces. (3) Fault rock consisting of poorly sorted angular grains, characterized by large variations in grain packing (pore size), and crack-seal textures. These different fault rocks are respectively associated with a high permeability upper boiling zone for the geothermal system, a conductively heated "caprock" at moderate to shallow depth associated with low permeability, and a deeper convectively heated region associated with enhanced permeability. Outcrop and hand-sample scale mapping, XRD analysis, and SEM secondary electron images of fault gouge and slip surfaces at different stages of development (estimated shear strain) are used to investigate the processes responsible for the development and physical properties of these distinct fault rocks. In each type of fault rock, mineral dissolution and re-precipitation in conjunction with the amount and geometry of porosity changes induced by dilation or compaction are the key controls on fault rock development. In addition, at the contacts between slip surfaces, abrasion and resulting comminution appear to influence grain size, sorting, and packing. Macroscopically, we expect the frictional strength of these characteristic fault rocks to differ because the processes that accommodate deformation depend strongly on mineralogy. Frictional strength of quartz-dominated fault rocks in the near surface and in the reservoir should be greater (~0.6) than that in the clay-dominated cap rock (~0.2-0.4). Similarly, permeability should be much lower in foliated clay-rich fault rocks than in quartz-rich fault rocks as evidenced by larger, more connected pores imaged in quartz-rich gouge. Mineral stability is a function of loading, strain rate, temperature, and fluid flow conditions. Which minerals form, and the rates at which they grow is also a key element in determining variations in the magnitude and anisotropy of fault zone properties at Coso. Consequently, we suggest that the development of fault-zone properties depends on the feedback between deformation, resulting changes in permeability, and large-scale fluid flow and the leading to dissolution/precipitation of minerals in the fault rock and adjacent host rock. The implication for Coso is that chemical alteration of otherwise low-porosity crystalline rocks appears to determine the distribution and temporal evolution of permeability in the actively deforming fracture network at small to moderate scales as well as along major, reservoir-penetrating fault zones.
Direct utilization of geothermal energy in the Peoples Republic of China

NASA Astrophysics Data System (ADS)

Lund, J. W.

1980-12-01

A brief review of the direct utilization of geothermal energy in three regions of the Peoples' Republic of China is presented, stressing a development outline for the next five to ten years. The geothermal resource of the Tianjin-Beijing area is mainly to be developed for space heating, whereas along the coastal area of Fujian and Guangdong, it will be developed for agriculture, and industrial and residential use. Electric power generation will be the main concern in the southwest at Tengchong. Most theoretical research will be done on geologic structure interpretation, corrosion of pump shafts and buried pipelines, and heat flow, with some interest in the study of geopressure and hot dry rock systems. Specific examples from the Tianjin area include a wool factory; a wool rug weaving shop; heating of a hotel; public bathing; and well drilling for apartment heating, fish breeding, and greenhouses. Direct use of geothermal energy in the Beijing area includes cotton dyeing, humidifying, medical purposes, and animal husbandry. Experimental geothermal electric power plants are summarized in table form.
Investigation of Microbial Diversity in Geothermal Hot Springs in Unkeshwar, India, Based on 16S rRNA Amplicon Metagenome Sequencing

PubMed Central

Mehetre, Gajanan T.; Paranjpe, Aditi; Dastager, Syed G.

2016-01-01

Microbial diversity in geothermal waters of the Unkeshwar hot springs in Maharashtra, India, was studied using 16S rRNA amplicon metagenomic sequencing. Taxonomic analysis revealed the presence of Bacteroidetes, Proteobacteria, Cyanobacteria, Actinobacteria, Archeae, and OD1 phyla. Metabolic function prediction analysis indicated a battery of biological information systems indicating rich and novel microbial diversity, with potential biotechnological applications in this niche. PMID:26950332
Capture of Geothermal Heat as Chemical Energy

DOE PAGES

Jody, Bassam J.; Petchsingto, Tawatchai; Doctor, Richard D.; ...

2015-12-11

In this paper, fluids that undergo endothermic reactions were evaluated as potential chemical energy carriers of heat from geothermal reservoirs for power generation. Their performance was compared with that of H 2O and CO 2. The results show that (a) chemical energy carriers can produce more power from geothermal reservoirs than water and CO 2 and (b) working fluids should not be selected solely on the basis of their specific thermo-physical properties but rather on the basis of the rate of exergy (ideal power) they can deliver. Finally, this article discusses the results of the evaluation of two chemical energymore » carrier systems: ammonia and methanol/water mixtures.« less
The Iceland Deep Drilling Project (IDDP): (I) Drilling for Supercritical Hydrothermal Fluids is Underway

NASA Astrophysics Data System (ADS)

Elders, W. A.; Fridleifsson, G. O.; Bird, D. K.; Reed, M. H.; Schiffman, P.; Zierenberg, R.

2008-12-01

The IDDP is being carried out by an international industry-government consortium in Iceland (consisting of three leading Icelandic power companies, together with the National Energy Authority), Alcoa Inc. and StatoilHydro) with the objective of investigating the economic feasibility of producing electricity from supercritical geothermal fluids. This will require drilling to temperatures of 400-600°C and depths of 4 to 5 km. Modeling suggests that supercritical water could yield an order of magnitude greater power output than that produced by conventional geothermal wells. The consortium plans to test this concept in three different geothermal fields in Iceland. If successful, major improvements in the development of high-temperature geothermal resources could result worldwide. In June 2008 preparation of the first deep IDDP well commenced in the Krafla volcanic caldera in the active rift zone of NE Iceland. Selection of the first drill site for this well was based on geological, geophysical and geochemical data, and on the results of extensive geothermal drilling since 1971. During 1975-1984, a rifting episode occurred in the caldera, involving 9 volcanic eruptions. In parts of the geothermal field acid volcanic gases made steam from some of the existing wells unsuitable for power generation for the following decade. A large magma chamber at 3-7 km depth was detected by S-wave attenuation beneath the center of the caldera, believed to be the heat source of the geothermal system. A recent MT-survey has confirmed the existence of low resistivity bodies at shallow depths within the volcano. The IDDP well will be drilled and cased to 800m depth in September, before the winter snows, and in spring 2009 it will be drilled and cased to 3.5km depth and then deepened to 4.5 km in July. Several spot cores for scientific studies will be collected between 2400m and the total depth. After the well heats, it will be flow tested and, if successful, a pilot plant for power production should follow in 2010. During 2009-19 two new wells, ~4 km deep, will be drilled at the Hengill and the Reykjanes geothermal fields in southern Iceland, and subsequently deepened into the supercritical zone. In contrast to the fresh water systems at Krafla and Hengill, the Reykjanes geothermal system produces hydrothermally modified seawater on the Reykjanes peninsula, where the Mid-Atlantic Ridge comes on land. Processes at depth at Reykjanes should be more similar to those responsible for black smokers on oceanic rift systems. Because of the considerable international scientific opportunities afforded by the IDDP, the US National Science Foundation and the International Continental Scientific Drilling Program will jointly fund the coring and sampling for scientific studies. Research is underway on samples from existing wells in the targeted geothermal fields, and on active mid-ocean ridge systems that have conditions believed to be similar to those that will be encountered in deep drilling by the IDDP. Some of these initial scientific studies by US investigators are reported in the accompanying papers.
Geochemical modelling of EGS fracture stimulation applying weak and strong acid treatments

NASA Astrophysics Data System (ADS)

Sigfusson, Bergur; Sif Pind Aradottir, Edda

2015-04-01

Engineered Geothermal systems (EGS) provide geothermal power by tapping into the Earth's deep geothermal resources that are otherwise not exploitable due to lack of water and fractures, location or rock type. EGS technologies have the potential to cost effectively produce large amounts of electricity almost anywhere in the world. The EGS technology creates permeability in the rock by hydro-fracturing the reservoir with cold water pumped into the first well (the injection well) at a high pressure. The second well (the production well) intersects the stimulated fracture system and returns the hot water to the surface where electricity can be generated. A significant technological hurdle is ensuring effective connection between the wells and the fracture system and to control the deep-rooted fractures (can exceed 5 000 m depth). A large area for heat transfer and sufficient mass flow needs to be ensured between wells without creating fast flowing paths in the fracture network. Maintaining flow through the fracture system can cause considerable energy penalty to the overall process. Therefore, chemical methods to maintain fractures and prevent scaling can be necessary to prevent excessive pressure build up in the re-injection wells of EGS systems. The effect of different acid treatments on the porosity development of selected rock types was simulated with the aid of the Petrasim interface to the Toughreact simulation code. The thermodynamic and kinetic database of Aradottir et al. (2014) was expanded to include new minerals and the most important fluoride bearing species involved in mineral reactions during acid stimulation of geothermal systems. A series of simulations with injection waters containing fluoric acid, hydrochloric acid and CO2 or mixtures thereof were then carried out and porosity development in the fracture system monitored. The periodic injection of weak acid mixtures into EGS systems may be cost effective in some isolated cases to prevent pressure build-up and therefore lowering pumping costs during operation. Selection of the acid is though highly dependent on the chemistry of the reservoir in question. Reference Aradottir, E. S. P., Gunnarsson, I., Sigfusson, B., Gunnarsson, G., Juliusson, B. M., Gunnlaugsson, E., Sigurdardóttir, H., Arnarson, M. T., Sonnenthal, E., 2014. Toward Cleaner Geothermal Energy Utilization: Capturing and Sequestering CO2 and H2S Emissions from Geothermal Power Plants. Transport in Porous Media. DOI 10.1007s/11242-014-0316-5
The potential contribution of geothermal energy to electricity supply in Saudi Arabia

NASA Astrophysics Data System (ADS)

Chandrasekharam, D.; Lashin, Aref; Al Arifi, Nassir

2016-10-01

With increase in demand for electricity at 7.5% per year, the major concern of Saudi Arabia is the amount of CO2 being emitted. The country has the potential of generating 200×106 kWh from hydrothermal sources and 120×106 terawatt hour from Enhanced Geothermal System (EGS) sources. In addition to electricity generation and desalination, the country has substantial source for direct application such as space cooling and heating, a sector that consumes 80% of the electricity generated from fossil fuels. Geothermal energy can offset easily 17 million kWh of electricity that is being used for desalination. At least a part of 181,000 Gg of CO2 emitted by conventional space cooling units can also be mitigated through ground-source heat pump technology immediately. Future development of EGS sources together with the wet geothermal systems will make the country stronger in terms of oil reserves saved and increase in exports.
Spectral Correlation of Thermal and Magnetotelluric Responses in a 2D Geothermal System

NASA Astrophysics Data System (ADS)

Pacheco, M. A.

2008-05-01

A methodology of thermal response observations at regional scale in geothermal systems was implemented using magnetotelluric(MT) data that was analyzed by spectral correlation of EM anomalies. Local favorability indices were obtained enhancing the anomalies of thermal flow and their corresponding magnetotelluric responses related to a common source. A C++ code was developed to compute magnetotelluric and thermal responses using finite differences of a geothermal field model. The problem of thermal convection was solved numerically using the approach of Boussinesq and temperature and thermal flow profiles are obtained, also is solved to the equations of electromagnetic induction 2D that govern the wave equation for the H-polarization case in a two-dimensional model of the system. This methodology is useful to find thermal anomalies in conductive or resistive structures of a geothermal system, which is directly associated with the litology of the model such as magmatic chamber, basement and hydrothermal reservoir.
Salt loaded heat pipes: steady-state operation and related heat and mass transport

NASA Astrophysics Data System (ADS)

Simakin, A.; Ghassemi, A.

2003-10-01

Fluids in the deep-seated zones (3.5-4.5 km) of active geothermal zones are known to have increased salinity and acidity that can enhance interaction with surrounding porous rocks. A possible mechanism for brine generation is the separation of the rising magmatic fluid into a gas-like and a liquid-like component. This work illustrates the main features of this mechanism by investigating the conditions for heat pipe convection of natural brines in hydrothermal systems. The well-established heat pipe regime for convection of two-phase pure water (vapor-liquid) in a porous column is extended to the case of boiling brines. In particular, the NaCl-H 2O system is used to model the 1-D reactive flow with dissolution-precipitation in geothermal reservoirs. The quasi steady-state equations of the conservation of matter, Darcy's law for the gas and liquid phases, and the heat balance equation have been examined while neglecting the temporal variation of porosity. A semi-analytical procedure is used to solve these equations for a two-phase fluid in equilibrium with a solid salt. The solution is in the form of the dependence of liquid volume fraction as a function of temperature for different heat fluxes. The solution is separated into two isolated regions by the temperature T=596°C, at the maximum fluid pressure for three-phase (H-L-V) equilibrium. In the case of unsaturated two-phase flow at the reference permeability of porous rocks (3·10 -16 m 2), the maximum heat flux that can be transferred through the porous column via convection is analytically estimated to be 4.3 W/m 2. This is close to the corresponding value for the three-phase case that is numerically calculated to be 6 W/m 2. Due to dissolution (partial leaching of oxide components by acid condensates) and precipitation of salt at the boiling front, heat transfer in a heat pipe in soluble media occurs in a direction opposite to the associated mass transfer. This can cause deep hydrothermal karsting that is manifested as surface subsidence at rates of about several cm/yr as observed in some active geothermal fields.
International Union of Theoretical and Applied Mechanics: Symposium on Adiabatic Waves in liquid-Vapor Systems Held at Goettingen (Germany, F.R.) on 28 August-1 September 1989. Abstracts of the Contributed Papers

DTIC Science & Technology

1989-09-01

THE LIQUID- VAPOR CRITICAL POINT" P.A. Thompson, J.E. Shepherd, H.J. Cho, S.Can Gulen (Troy). Non-euilibrium in dinamic systems , critical phenomena...IN LIQUID-VAPOR SYSTEMS G~ttingen: 28. August - 1. September 1989 Chairmen: Gerd E.A. Meier & Philip A. Thompson Secretary: Tomasz A. Kowalewski...is a great pleasure to welcome you on behalf of the Organizing Committee to the IUTAM Symposium on Adiabatic Waves in Liquid Vapor Systems . We are
Electric power generation using geothermal brine resources for a proof of concept facility

NASA Technical Reports Server (NTRS)

Hankin, J. W.

1974-01-01

An exploratory systems study of a geothermal proof-of-concept facility is being conducted. This study is the initial phase (Phase 0) of a project to establish the technical and economic feasibility of using hot brine resources for electric power production and other industrial applications. Phase 0 includes the conceptual design of an experimental test-bed facility and a 10-MWe power generating facility.
High-temperature Y267 epdm elastomer - field and laboratory experiences, August 1981

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hirasuna, A.R.; Friese, G.J.; Stephens, G.A.

1982-01-01

During the period 1976 to 1979 L'Garde, Inc. developed geothermal elastomer compounds under a U.S. Department of Energy - Division of Geothermal Energy (DOE-DGE) contract. The resulting developments yielded compounds from 4 polymer systems which successfully exceeded the contract requirements. Since completion of the compound development, significant laboratory and down-hole experience occurred, primarily on the Y267 EPDM compound. This work summarizes those experiences. 11 references.
Volcano-tectonic structures, gravity and helium in geothermal areas of Tuscany and Latium (Vulsini volcanic district), Italy

USGS Publications Warehouse

Di, Filippo M.; Lombardi, S.; Nappi, G.; Reimer, G.M.; Renzulli, A.; Toro, B.

1999-01-01

Since the early 1980s, geological and structural mapping, gravity, and helium soil-gas studies have been performed in the eastern sector of the Vulsini Volcanic District (Roman Magmatic Province) in an attempt to locate potential geothermal reservoirs. This area is characterised by an anomalous geothermal gradient of > 100??C/km, and by widespread hydrothermal mineralization, thermal springs, high gas fluxes, and fossil and current travertine deposits. The results of these surveys indicate the existence of a number of fault systems, with N-S and E-W structures that appear to be superimposed on older NW-SE and NE-SW features. Comparison of the results of the various studies also reveals differences in permeability and potential reservoir structures at depth.Since the early 1980s, geological and structural mapping, gravity, and helium soil-gas studies have been performed in the eastern sector of the Vulsini Volcanic District (Roman Magmatic Province) in an attempt to locate potential geothermal reservoirs. This area is characterised by an anomalous geothermal gradient of > 100??C/km, and by widespread hydrothermal mineralization, thermal springs, high gas fluxes, and fossil and current travertine deposits. The results of these surveys indicate the existence of a number of fault systems, with N-S and E-W structures that appear to be superimposed on older NW-SE and NE-SW features. Comparison of the results of the various studies also reveals differences in permeability and potential reservoir structures at depth.
Trends in Solar energy Driven Vertical Ground Source Heat Pump Systems in Sweden - An Analysis Based on the Swedish Well Database

NASA Astrophysics Data System (ADS)

Juhlin, K.; Gehlin, S.

2016-12-01

Sweden is a world leader in developing and using vertical ground source heat pump (GSHP) technology. GSHP systems extract passively stored solar energy in the ground and the Earth's natural geothermal energy. Geothermal energy is an admitted renewable energy source in Sweden since 2007 and is the third largest renewable energy source in the country today. The Geological Survey of Sweden (SGU) is the authority in Sweden that provides open access geological data of rock, soil and groundwater for the public. All wells drilled must be registered in the SGU Well Database and it is the well driller's duty to submit registration of drilled wells.Both active and passive geothermal energy systems are in use. Large GSHP systems, with at least 20 boreholes, are active geothermal energy systems. Energy is stored in the ground which allows both comfort heating and cooling to be extracted. Active systems are therefore relevant for larger properties and industrial buildings. Since 1978 more than 600 000 wells (water wells, GSHP boreholes etc) have been registered in the Well Database, with around 20 000 new registrations per year. Of these wells an estimated 320 000 wells are registered as GSHP boreholes. The vast majority of these boreholes are single boreholes for single-family houses. The number of properties with registered vertical borehole GSHP installations amounts to approximately 243 000. Of these sites between 300-350 are large GSHP systems with at least 20 boreholes. While the increase in number of new registrations for smaller homes and households has slowed down after the rapid development in the 80's and 90's, the larger installations for commercial and industrial buildings have increased in numbers over the last ten years. This poster uses data from the SGU Well Database to quantify and analyze the trends in vertical GSHP systems reported between 1978-2015 in Sweden, with special focus on large systems. From the new aggregated data, conclusions can be drawn about the development of larger vertical GSHP system installments over the years and the geographical distribution in Sweden.

Geologic setting of the proposed West Flank Forge Site, California: Suitability for EGS research and development

USGS Publications Warehouse

Sabin, Andrew; Blake, Kelly; Lazaro, Mike; Blankenship, Douglas; Kennedy, Mack; McCullough, Jess; DeOreo, S.B.; Hickman, Stephen H.; Glen, Jonathan; Kaven, Joern; Williams, Colin F.; Phelps, Geoffrey; Faulds, James E.; Hinz, Nicholas H.; Calvin, Wendy M.; Siler, Drew; Robertson-Tait, Ann

2017-01-01

The proposed West Flank FORGE site is within the China Lake Naval Air Weapons Station (NAWS), China Lake, CA. The West Flank is west of the Coso geothermal field, an area of China Lake NAWS dominated by the Quaternary Coso volcanic field largely comprised of rhyolite domes and their volcaniclastic and epiclastic horizons. The largest dome flow complex, Sugarloaf Mountain, marks the northwestern margin of the geothermal field. The West Flank is situated due west of Sugarloaf. The geologic setting of the West Flank was determined from one deep well (83-11) drilled as a potential production hole in 2009. The bottom-hole temperature (BHT) of well 83-11 approaches 600 oF (315˚C), but flow tests demonstrate very low, non-commercial permeabilities. With the exception of the upper 600 feet of volcaniclastic alluvium, well 83-11 is completed in granitic basement. The West Flank possesses the primary attributes of a FORGE site: non-commercial permeability (<10-16m2), a 175˚ to 225˚C temperature range in crystalline rocks, and a location outside an existing geothermal fieldThe Coso Mountains host the Coso volcanic field and are within a right-releasing stepover between the dextral Airport Lake (ALF) and Little Lake fault zones (LLFZ) and the Wild Horse Mesa and Owens Valley faults. Two distinct fault populations have been identified at Coso: WNW-trending and antithetical, NE-trending strike-slip faults and N- to NNE-trending normal faults. These faults are both high permeability drilling targets at depth within the main (productive) geothermal field and they locally segment the field into distinct hydrothermal regimes. The West Flank may be segmented from the rest of the field by one such northerly trending fault. The overall minimum principal stress orientation in the main geothermal field varies from 103˚ to 108˚; however, the minimum horizontal principal stress in 83-11 is rotated to 081˚.
Low-level water vapor fields from the VISSR atmospheric sounder (VAS) split window channels at 11 and 12 microns. [visible infrared spin scan radiometer

NASA Technical Reports Server (NTRS)

Chesters, D.; Uccellini, L.; Robinson, W.

1982-01-01

A series of high-resolution water vapor fields were derived from the 11 and 12 micron channels of the VISSR Atmospheric Sounder (VAS) on GOES-5. The low-level tropospheric moisture content was separated from the surface and atmospheric radiances by using the differential adsorption across the 'split window' along with the average air temperature from imbedded radiosondes. Fields of precipitable water are presented in a time sequence of five false color images taken over the United States at 3-hour intervals. Vivid subsynoptic and mesoscale patterns evolve at 15 km horizontal resolution over the 12-hour observing period. Convective cloud formations develop from several areas of enhanced low-level water vapor, especially where the vertical water vapor gradient relatively strong. Independent verification at radiosonde sites indicates fairly good absolute accuracy, and the spatial and temporal continuity of the water vapor features indicates very good relative accuracy. Residual errors are dominated by radiometer noise and unresolved clouds.
Geothermal reservoir simulation of hot sedimentary aquifer system using FEFLOW®

NASA Astrophysics Data System (ADS)

Nur Hidayat, Hardi; Gala Permana, Maximillian

2017-12-01

The study presents the simulation of hot sedimentary aquifer for geothermal utilization. Hot sedimentary aquifer (HSA) is a conduction-dominated hydrothermal play type utilizing deep aquifer, which is heated by near normal heat flow. One of the examples of HSA is Bavarian Molasse Basin in South Germany. This system typically uses doublet wells: an injection and production well. The simulation was run for 3650 days of simulation time. The technical feasibility and performance are analysed in regards to the extracted energy from this concept. Several parameters are compared to determine the model performance. Parameters such as reservoir characteristics, temperature information and well information are defined. Several assumptions are also defined to simplify the simulation process. The main results of the simulation are heat period budget or total extracted heat energy, and heat rate budget or heat production rate. Qualitative approaches for sensitivity analysis are conducted by using five parameters in which assigned lower and higher value scenarios.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Hinz, Nick; Coolbaugh, Mark; Shevenell, Lisa

There are currently 74 productive geothermal systems associated with volcanic centers (VCs) in arcs globally, including actively producing systems, past producing systems, and systems with successful flow tests. The total installed or tested capacity of these 74 geothermal systems is 7,605 MWe, ranging from 0.7 MWe each at Copahue, Chile and Barkhatnaya Sopka, Kamchatka to 795 MWe, Larderello, Italy, and averaging 90.5 MWe per system. These 74 productive VCs constitute 10% of 732 VCs distributed across more than a dozen major arcs around the world. The intra-arc (within-arc) tectonic setting is highly variable globally, ranging from extension to transtension, transpression,more » or compression. Furthermore, the shear strain associated with oblique plate convergence can be accommodated by either intra-arc or arc-marginal deformation. The structural-tectonic settings of these 74 productive VCs were characterized to add to a global catalog of parameters to help guide future exploration, development, and regional resource potential.« less
Effects of geothermal activity and primary production on molybdenum isotopes: Lake Mývatn, Iceland

NASA Astrophysics Data System (ADS)

Neely, R.; Gíslason, S. R.; Ólafsson, M.; Pearce, C. R.; Torssander, P.; Eiríksdóttir, E. S.; Burton, K. W.

2016-12-01

Molybdenum (Mo) is highly sensitive to oxidation state and its isotopes are used as a proxy for redox conditions in the palaeoenvironent, particularly in the oceans. Geothermal systems play an important role in element cycles, comprising 10% of the Mo flux to the oceans and the dominant mechanism for Mo ore formation in porphyry deposits. Currently, little is known about Mo isotopes in either geothermal or groundwaters or how these systems may affect global mass balance. This study takes the Lake Mývatn area as a natural laboratory to study both geothermally affected and unaffected groundwaters, along with seasonal variations in a lacustrine environment. We present a comprehensive elemental and Mo isotope study of two groundwater systems from a basaltic terrain in North Iceland. The waters are of meteoric origin, range in sampling temperature from 2-93°C and in Mo isotope composition (δ98MoNIST) from -0.40 to 1.81‰. The Mo isotopic signature of the waters is largely controlled by mixing between cold groundwaters (isotopically light) and a geothermal end member (isotopically heavy). One of these groundwater systems forms the only input into Lake Mývatn: one of the most productive lakes in the northern hemisphere. Here we also present a time series from the Laxá River, which is the only outflow from the lake. Whilst seasonal variations in Mo isotopes are small (from δ98MoNIST 0.1 to 0.3‰) they positively correlate (R2 = 0.8) with variations in δ34S (from δ43S 1.7 to 4.6‰) with a shift to a heavier isotope peaks in late summer (September). This increase in δ98Mo coincides with a documented cyanobacteria bloom in late July to early September, known to preferentially use light isotopes.
Geological model of supercritical geothermal reservoir related to subduction system

NASA Astrophysics Data System (ADS)

Tsuchiya, Noriyoshi

2017-04-01

Following the Great East Japan Earthquake and the accident at the Fukushima Daiichi Nuclear power station on 3.11 (11th March) 2011, geothermal energy came to be considered one of the most promising sources of renewable energy for the future in Japan. The temperatures of geothermal fields operating in Japan range from 200 to 300 °C (average 250 °C), and the depths range from 1000 to 2000 m (average 1500 m). In conventional geothermal reservoirs, the mechanical behavior of the rocks is presumed to be brittle, and convection of the hydrothermal fluid through existing network is the main method of circulation in the reservoir. In order to minimize induced seismicity, a rock mass that is "beyond brittle" is one possible candidate, because the rock mechanics of "beyond brittle" material is one of plastic deformation rather than brittle failure. Supercritical geothermal resources could be evaluated in terms of present volcanic activities, thermal structure, dimension of hydrothermal circulation, properties of fracture system, depth of heat source, depth of brittle factures zone, dimension of geothermal reservoir. On the basis of the GIS, potential of supercritical geothermal resources could be characterized into the following four categories. 1. Promising: surface manifestation d shallow high temperature, 2 Probability: high geothermal gradient, 3 Possibility: Aseismic zone which indicates an existence of melt, 4 Potential : low velocity zone which indicates magma input. Base on geophysical data for geothermal reservoirs, we have propose adequate tectonic model of development of the supercritical geothermal reservoirs. To understand the geological model of a supercritical geothermal reservoir, granite-porphyry system, which had been formed in subduction zone, was investigated as a natural analog of the supercritical geothermal energy system. Quartz veins, hydrothermal breccia veins, and glassy veins are observed in a granitic body. The glassy veins formed at 500-550 °C under lithostatic pressures, and then pressures dropped drastically. The solubility of silica also dropped, resulting in formation of quartz veins under a hydrostatic pressure regime. Connections between the lithostatic and hydrostatic pressure regimes were key to the formation of the hydrothermal breccia veins, and the granite-porphyry system provides useful information for creation of fracture clouds in supercritical geothermal reservoirs. A granite-porphyry system, associated with hydrothermal activity and mineralization, provides a suitable natural analog for studying a deep-seated geothermal reservoir where stockwork fracture systems are created in the presence of supercritical geothermal fluids. I describe fracture networks and their formation mechanisms using petrology and fluid inclusion studies in order to understand this "beyond brittle" supercritical geothermal reservoir, and a geological model for "Beyond Brittle" and "Supercritical" geothermal reservoir in the subduction zone were was revealed.
Notre Dame Geothermal Ionic Liquids Research: Ionic Liquids for Utilization of Geothermal Energy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Brennecke, Joan F.

The goal of this project was to develop ionic liquids for two geothermal energy related applications. The first goal was to design ionic liquids as high temperature heat transfer fluids. We identified appropriate compounds based on both experiments and molecular simulations. We synthesized the new ILs, and measured their thermal stability, measured storage density, viscosity, and thermal conductivity. We found that the most promising compounds for this application are aminopyridinium bis(trifluoromethylsulfonyl)imide based ILs. We also performed some measurements of thermal stability of IL mixtures and used molecular simulations to better understand the thermal conductivity of nanofluids (i.e., mixtures of ILsmore » and nanoparticles). We found that the mixtures do not follow ideal mixture theories and that the addition of nanoparticles to ILs may well have a beneficial influence on the thermal and transport properties of IL-based heat transfer fluids. The second goal was to use ionic liquids in geothermally driven absorption refrigeration systems. We performed copious thermodynamic measurements and modeling of ionic liquid/water systems, including modeling of the absorption refrigeration systems and the resulting coefficients of performance. We explored some IL/organic solvent mixtures as candidates for this application, both with experimentation and molecular simulations. We found that the COPs of all of the IL/water systems were higher than the conventional system – LiBr/H2O. Thus, IL/water systems appear very attractive for absorption refrigeration applications.« less
Chad Augustine | NREL

Science.gov Websites

(EGS) Geothermal resource assessment High pressure, high temperature reaction systems Research Interests EGS demonstration and deployment Advanced drilling systems research Thermodynamics and process Phenomenological Experimental Demonstrations to Quantitative Understanding." Journal of Supercritical Fluids
CO2 Push-Pull Single Fault Injection Simulations

DOE Data Explorer

Borgia, Andrea; Oldenburg, Curtis (ORCID:0000000201326016); Zhang, Rui; Pan, Lehua; Daley, Thomas M.; Finsterle, Stefan; Ramakrishnan, T.S.; Doughty, Christine; Jung, Yoojin; Lee, Kyung Jae; Altundas, Bilgin; Chugunov, Nikita

2017-09-21

ASCII text files containing grid-block name, X-Y-Z location, and multiple parameters from TOUGH2 simulation output of CO2 injection into an idealized single fault representing a dipping normal fault at the Desert Peak geothermal field (readable by GMS). The fault is composed of a damage zone, a fault gouge and a slip plane. The runs are described in detail in the following: Borgia A., Oldenburg C.M., Zhang R., Jung Y., Lee K.J., Doughty C., Daley T.M., Chugunov N., Altundas B, Ramakrishnan T.S., 2017. Carbon Dioxide Injection for Enhanced Characterization of Faults and Fractures in Geothermal Systems. Proceedings of the 42st Workshop on Geothermal Reservoir Engineering, Stanford University, Stanford, California, February 13-17.
DOE Office of Scientific and Technical Information (OSTI.GOV)

Earl D Mattson; Ghanashyam Neupane; Mitchell Plummer

Long-term sustainability of fracture conductivity is critical for commercial success of engineered geothermal system (EGS) and hydrogeothermal field sites. The injection of proppants has been suggested as a means to enhance the conductivity in these systems. Several studies have examined the chemical behavior of proppants that are not at chemical equilibrium with the reservoir rock and water. These studies have suggested that in geothermal systems, geochemical reactions can lead to enhance proppant dissolution and deposition alteration minerals. We hypothesize that proppant dissolution will decrease the strength of the proppant and can potentially reduce the conductivity of the fracture. To examinemore » the geomechanical strength of proppants, we have performed modified crushing tests of proppants and reservoir rock material that was subjected to geothermal reservoir temperature conditions. The batch reactor experiments heated crushed quartz monzonite rock material, proppants (either quartz sand, sintered bauxite or kryptospheres) with Raft River geothermal water to 250 ºC for a period of 2 months. Solid and liquid samples were shipped to University of Utah for chemical characterization with ICP-OES, ICP-MS, and SEM. A separate portion of the rock/proppant material was subjected to a modified American Petroleum Institute ISO 13503-2 proppant crushing test. This test is typically used to determine the maximum stress level that can be applied to a proppant pack without the occurrence of unacceptable proppant crushing. We will use the test results to examine potential changes in proppant/reservoir rock geomechanical properties as compared to samples that have not been subjected to geothermal conditions. These preliminary results will be used to screen the proppants for long term use in EGS and hot hydrogeothermal systems.« less
Structural Orientations Adjacent to Some Colorado Geothermal Systems

DOE Data Explorer

Richard

2012-02-01

Structural orientations (fractures, joints, faults, lineaments, bedding orientations, etc.) were collected with a standard Brunton compass during routine field examinations of geothermal phenomena in Colorado. Often multiple orientations were taken from one outcrop. Care was taken to ensure outcrops were "in place". Point data was collected with a hand-held GPS unit. The structural data is presented both as standard quadrant measurements and in format suitable for ESRI symbology
The evolution of the Cappadocia Geothermal Province, Anatolia (Turkey): geochemical and geochronological evidence

NASA Astrophysics Data System (ADS)

Şener, M. Furkan; Şener, Mehmet; Uysal, I. Tonguç

2017-12-01

Cappadocia Geothermal Province (CGP), central Turkey, consists of nine individual geothermal regions controlled by active regional fault systems. This paper examines the age dating of alteration minerals and the geochemistry (trace elements and isotopes) of the alteration minerals and geothermal waters, to assess the evolution of CGP in relation to regional tectonics. Ar-Ar age data of jarosite and alunite show that the host rocks were exposed to oxidizing conditions near the Earth's surface at about 5.30 Ma. Based on the δ18O-δD relationhip, water samples had a high altitude meteoric origin. The δ34S values of jarosite and alunite indicate that water samples from the southern part of the study area reached the surface after circulation through volcanic rocks, while northern samples had traveled to the surface after interacting with evaporates at greater depths. REY (rare earth elements and yttrium) diagrams of alteration minerals (especially illite, jarosite and alunite) from rock samples, taken from the same locations as the water samples, display a similar REY pattern to water samples. This suggests that thermal fluids, which reached the surface along a fault zone and caused the mineral alteration in the past, had similar chemical composition to the current geothermal water. The geothermal conceptual model, which defines a volcanically heated reservoir and cap rocks, suggests there are no structural drawbacks to the use of the CGP geothermal system as a resource. However, fluid is insufficient to drive the geothermal system as a result of scanty supply of meteoric water due to evaporation significantly exceeding rainfall.
Reservoir Maintenance and Development Task Report for the DOE Geothermal Technologies Office GeoVision Study.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lowry, Thomas Stephen; Finger, John T.; Carrigan, Charles R.

This report documents the key findings from the Reservoir Maintenance and Development (RM&D) Task of the U.S. Department of Energy's (DOE), Geothermal Technologies Office (GTO) Geothermal Vision Study (GeoVision Study). The GeoVision Study had the objective of conducting analyses of future geothermal growth based on sets of current and future geothermal technology developments. The RM&D Task is one of seven tasks within the GeoVision Study with the others being, Exploration and Confirmation, Potential to Penetration, Institutional Market Barriers, Environmental and Social Impacts, Thermal Applications, and Hybrid Systems. The full set of findings and the details of the GeoVision Study canmore » be found in the final GeoVision Study report on the DOE-GTO website. As applied here, RM&D refers to the activities associated with developing, exploiting, and maintaining a known geothermal resource. It assumes that the site has already been vetted and that the resource has been evaluated to be of sufficient quality to move towards full-scale development. It also assumes that the resource is to be developed for power generation, as opposed to low-temperature or direct use applications. This document presents the key factors influencing RM&D from both a technological and operational standpoint and provides a baseline of its current state. It also looks forward to describe areas of research and development that must be pursued if the development geothermal energy is to reach its full potential.« less
Maps, Models and Data from Southeastern Great Basin PFA, Phase II Project

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nash, Greg

This submission includes composite risk segment models in raster format for permeability, heat of the earth, and MT, as well as the final PFA model of geothermal exploration risk in Southwestern Utah, USA. Additionally, this submission has data regarding hydrothermally altered areas, and opal sinter deposits in the study area. All of this information lends to the understanding and exploration for hidden geothermal systems in the area.
Exploration drilling and reservoir model of the Platanares geothermal system, Honduras, Central America

USGS Publications Warehouse

Goff, F.; Goff, S.J.; Kelkar, S.; Shevenell, L.; Truesdell, A.H.; Musgrave, J.; Rufenacht, H.; Flores, W.

1991-01-01

Results of drilling, logging, and testing of three exploration core holes, combined with results of geologic and hydrogeochemical investigations, have been used to present a reservoir model of the Platanares geothermal system, Honduras. Geothermal fluids circulate at depths ??? 1.5 km in a region of active tectonism devoid of Quaternary volcanism. Large, artesian water entries of 160 to 165??C geothermal fluid in two core holes at 625 to 644 m and 460 to 635 m depth have maximum flow rates of roughly 355 and 560 l/min, respectively, which are equivalent to power outputs of about 3.1 and 5.1 MW(thermal). Dilute, alkali-chloride reservoir fluids (TDS ??? 1200 mg/kg) are produced from fractured Miocene andesite and Cretaceous to Eocene redbeds that are hydrothermally altered. Fracture permeabillity in producing horizons is locally greater than 1500 and bulk porosity is ??? 6%. A simple, fracture-dominated, volume-impedance model assuming turbulent flow indicates that the calculated reservoir storage capacity of each flowing hole is approximately 9.7 ?? 106 l/(kg cm-2), Tritium data indicate a mean residence time of 450 yr for water in the reservoir. Multiplying the natural fluid discharge rate by the mean residence time gives an estimated water volume of the Platanares system of ??? 0.78 km3. Downward continuation of a 139??C/km "conductive" gradient at a depth of 400 m in a third core hole implies that the depth to a 225??C source reservoir (predicted from chemical geothermometers) is at least 1.5 km. Uranium-thorium disequilibrium ages on calcite veins at the surface and in the core holes indicate that the present Platanares hydrothermal system has been active for the last 0.25 m.y. ?? 1991.
Vibrationally Excited Carbon Monoxide Produced via a Chemical Reaction Between Carbon Vapor and Oxygen

NASA Astrophysics Data System (ADS)

Jans, Elijah R.; Eckert, Zakari; Frederickson, Kraig; Rich, Bill; Adamovich, Igor V.

2017-06-01

Measurements of the vibrational distribution function of carbon monoxide produced via a reaction between carbon vapor and molecular oxygen has shown a total population inversion on vibrational levels 4-7. Carbon vapor, produced using an arc discharge to sublimate graphite, is mixed with an argon oxygen flow. The excited carbon monoxide is vibrationally populated up to level v=14, at low temperatures, T=400-450 K, in a collision-dominated environment, 15-20 Torr, with total population inversions between v=4-7. The average vibrational energy per CO molecule formed by the reaction is 0.6-1.2 eV/molecule, which corresponds to 10-20% of the reaction enthalpy. Kinetic modeling of the flow reactor, including state specific vibrational processes, was performed to infer the vibrational distribution of the products of the reaction. The results show viability of developing of a new chemical CO laser from the reaction of carbon vapor and oxygen.
Alaskan Permafrost Analogs of Martian Small Valley Networks, Thermokarst, Terrain Softening, Terraces, and Volcanic Craters

NASA Technical Reports Server (NTRS)

Kargel, Jeffrey S.; Wessels, Rick; Beget, James E.; Eddy, Thomas; Lloyd, Sandra; Macaulay, Don; Proch, Mark; Skinner, Jim; Tanaka, Kenneth L.

2004-01-01

A geomorphic landscape analog in the Bering Land Bridge National Preserve (Alaska) offers a model for Mars where (1) fluvial and alluvial deposition, volcanism, and other processes first produced a layered ice-rich upper crust, and then (2) severe permafrost conditions (mild by today's Martian standards) and heterogeneous heat flow and volcanism have modified this terrain to produce a geomorphic areal mosaic that is alternately dominated by (a) geothermal meltwater and sublimation (bottom-up heat flow) and (b) surface-driven meltwater and sublimation (top-down heat flow).
Are modern geothermal waters in northwest Nevada forming epithermal gold deposits?

USGS Publications Warehouse

Breit, George N.; Hunt, Andrew G.; Wolf, Ruth E.; Koenig, Alan E.; Fifarek, Richard; Coolbaugh, Mark F.

2010-01-01

Hydrothermal systems currently are active near some gold deposits in northwestern Nevada. Possible links of these modern systems to gold mineralization were evaluated by chemically and isotopically analyzing water samples from the Brady, Dixie Valley, Humboldt House, San Emidio-Empire, Soda Lake, and Wabuska geothermal areas. In addition, quartz veins from Humboldt House and the adjacent Florida Canyon Mine were analyzed to compare ore and gangue phases with those predicted to form from proximal hydrothermal fluids.Nearly all water samples are alkali-chloride-type. Total dissolved solids range from 800 to 3900 mg/L, and pH varies from 5.6 to 7.8. Geochemical modeling with SOLVEQ, WATCH, and CHILLER predict the precipitation of silica in all systems during cooling. Anhydrite, calcite, barite, pyrite, base-metal sulfides, and alumino-silicates are variably saturated at calculated reservoir temperatures and also precipitate during boiling/cooling of some fluids. Measured dissolved gold concentrations are low (<0.2μg/L), but are generally consistent with contents predicted by equilibrium of sampled solutions with elemental gold at reservoir temperatures. Although the modern geothermal waters can precipitate ore minerals, the low gold and other ore metal concentrations require very large fluid volumes to form a deposit of economic interest.
Geophysical techniques for low enthalpy geothermal exploration in New Zealand

NASA Astrophysics Data System (ADS)

Soengkono, Supri; Bromley, Chris; Reeves, Robert; Bennie, Stewart; Graham, Duncan

2013-05-01

Shallow warm water resources associated with low enthalpy geothermal systems are often difficult to explore using geophysical techniques, mainly because the warm water creates an insufficient physical change from the host rocks to be easily detectable. In addition, often the system also has a limited or narrow size. However, appropriate use of geophysical techniques can still help the exploration and further investigation of low enthalpy geothermal resources. We present case studies on the use of geophysical techniques for shallow warm water explorations over a variety of settings in New Zealand (mostly in the North Island) with variable degrees of success. A simple and direct method for the exploration of warm water systems is shallow temperature measurements. In some New Zealand examples, measurements of near surface temperatures helped to trace the extent of deeper thermal water. The gravity method was utilised as a structural technique for the exploration of some warm water systems in New Zealand. Our case studies show the technique can be useful in identifying basement depths and tracing fault systems associated with the occurrence of hot springs. Direct current (DC) ground resistivity measurements using a variety of electrode arrays have been the most common method for the exploration of low enthalpy geothermal resources in New Zealand. The technique can be used to detect the extent of shallow warm waters that are more electrically conductive than the surrounding cold groundwater. Ground resistivity investigations using the electromagnetic (EM) techniques of audio magnetotellurics (AMT or shallow MT), controlled source audio magnetotellurics (CSAMT) and transient electromagnetic (TEM) methods have also been used. Highly conductive clays of thermal or sedimentary origin often limit the penetration depth of the resistivity techniques and can create some interpretation difficulties. Interpretation of resistivity anomalies needs to be treated in a site specific manner.
An Excel®-based visualization tool of 2-D soil gas concentration profiles in petroleum vapor intrusion.

PubMed

Verginelli, Iason; Yao, Yijun; Suuberg, Eric M

2016-01-01

In this study we present a petroleum vapor intrusion tool implemented in Microsoft ® Excel ® using Visual Basic for Applications (VBA) and integrated within a graphical interface. The latter helps users easily visualize two-dimensional soil gas concentration profiles and indoor concentrations as a function of site-specific conditions such as source strength and depth, biodegradation reaction rate constant, soil characteristics and building features. This tool is based on a two-dimensional explicit analytical model that combines steady-state diffusion-dominated vapor transport in a homogeneous soil with a piecewise first-order aerobic biodegradation model, in which rate is limited by oxygen availability. As recommended in the recently released United States Environmental Protection Agency's final Petroleum Vapor Intrusion guidance, a sensitivity analysis and a simplified Monte Carlo uncertainty analysis are also included in the spreadsheet.

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