Workshop Report: International Workshop to Explore Synergies between Nuclear and Renewable Energy Sources as a Key Component in Developing Pathways to Decarbonization of the Energy Sector

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

Bragg-Sitton, Shannon M.; Boardman, Richard; Ruth, Mark

2016-08-01

An international workshop was organized in June 2016 to explore synergies between nuclear and renewable energy sources. Synergies crossing electricity, transportation, and industrial sectors were the focus of the workshop, recognizing that deep decarbonization will require efforts that go far beyond the electricity sector alone. This report summarizes the key points made within each presentation and highlights outcomes that were arrived at in the discussions.

U.S. electric power sector transitions required to achieve 80% reductions in economy-wide greenhouse gas emissions: Results based on a state-level model of the U.S. energy system

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

Iyer, Gokul C.; Clarke, Leon E.; Edmonds, James A.

The United States has articulated a deep decarbonization strategy for achieving a reduction in economy-wide greenhouse gas (GHG) emissions of 80% below 2005 levels by 2050. Achieving such deep emissions reductions will entail a major transformation of the energy system and of the electric power sector in particular. , This study uses a detailed state-level model of the U.S. energy system embedded within a global integrated assessment model (GCAM-USA) to demonstrate pathways for the evolution of the U.S. electric power sector that achieve 80% economy-wide reductions in GHG emissions by 2050. The pathways presented in this report are based onmore » feedback received during a workshop of experts organized by the U.S. Department of Energy’s Office of Energy Policy and Systems Analysis. Our analysis demonstrates that achieving deep decarbonization by 2050 will require substantial decarbonization of the electric power sector resulting in an increase in the deployment of zero-carbon and low-carbon technologies such as renewables and carbon capture utilization and storage. The present results also show that the degree to which the electric power sector will need to decarbonize and low-carbon technologies will need to deploy depends on the nature of technological advances in the energy sector, the ability of end-use sectors to electrify and level of electricity demand.« less

Implications of Deep Decarbonization for Carbon Cycle Science

NASA Astrophysics Data System (ADS)

Jones, A. D.; Williams, J.; Torn, M. S.

2016-12-01

The energy-system transformations required to achieve deep decarbonization in the United States, defined as a reduction of greenhouse gas emissions of 80% or more below 1990 levels by 2050, have profound implications for carbon cycle science, particularly with respect to 4 key objectives: understanding and enhancing the terrestrial carbon sink, using bioenergy sustainably, controlling non-CO2 GHGs, and emissions monitoring and verification. (1) As a source of mitigation, the terrestrial carbon sink is pivotal but uncertain, and changes in the expected sink may significantly affect the overall cost of mitigation. Yet the dynamics of the sink under changing climatic conditions, and the potential to protect and enhance the sink through land management, are poorly understood. Policy urgently requires an integrative research program that links basic science knowledge to land management practices. (2) Biomass resources can fill critical energy needs in a deeply decarbonized system, but current understanding of sustainability and lifecycle carbon aspects is limited. Mitigation policy needs better understanding of the sustainable amount, types, and cost of bioenergy feedstocks, their interactions with other land uses, and more efficient and reliable monitoring of embedded carbon. (3) As CO2 emissions from energy decrease under deep decarbonization, the relative share of non-CO2 GHGs grows larger and their mitigation more important. Because the sources tend to be distributed, variable, and uncertain, they have been under-researched. Policy needs a better understanding of mitigation priorities and costs, informed by deeper research in key areas such as fugitive CH4, fertilizer-derived N2O, and industrial F-gases. (4) The M&V challenge under deep decarbonization changes with a steep decrease in the combustion CO2 sources due to widespread electrification, while a greater share of CO2 releases is net-carbon-neutral. Similarly, gas pipelines may carry an increasing share of methane from biogenic or other net carbon-neutral sources. Improved lifecycle analysis will be needed to verify carbon neutrality, while the signal-to-noise challenge for attributing CO2 to fossil or biogenic fuels becomes more challenging.

The British Climate Change Act: a critical evaluation and proposed alternative approach

NASA Astrophysics Data System (ADS)

Pielke, Roger A., Jr.

2009-04-01

This paper evaluates the United Kingdom's Climate Change Act of 2008 in terms of the implied rates of decarbonization of the UK economy for a short-term and a long-term target established in law. The paper uses the Kaya identity to structure the evaluation, employing both a bottom up approach (based on projections of future UK population, economic growth, and technology) and a top down approach (deriving implied rates of decarbonization consistent with the targets and various rates of projected economic growth). Both approaches indicate that the UK economy would have to achieve annual rates of decarbonization in excess of 4 or 5%. To place these numbers in context, the UK would have to achieve the 2006 carbon efficiency of France by about 2015, a level of effort comparable to the building of about 30 new nuclear power plants, displacing an equivalent amount of fossil energy. The paper argues that the magnitude of the task implied by the UK Climate Change Act strongly suggests that it is on course to fail, and discusses implications.

Carbon Retention and Isotopic Evolution in Deeply Subducted Sediments: Evidence from the Italian Alps

NASA Astrophysics Data System (ADS)

Cook-Kollars, J.; Bebout, G. E.; Agard, P.; Angiboust, S.

2012-12-01

Subduction-zone metamorphism of oceanic crust and carbonate-rich seafloor sediments plays an important regulatory role in the global C cycle by controlling the fraction of subducting C entering long-term storage in the mantle and the fraction of subducting C emitted into the atmosphere in arc volcanic gases. Modeling studies suggest that the extent of decarbonation of subducting sediments could be strongly affected by extents of infiltration by external H2O-rich fluids and that, in cool subduction zones, the dehydration of subducting oceanic slabs may not release sufficient H2O to cause significant decarbonation of overlying sediments [Gorman et al. (2006), G-cubed; Hacker (2008), G-cubed]. Metasedimentary suites in the Western Alps (sampled from the Schistes Lustres, Zermatt-Saas ophiolite, and at Lago di Cignana) were subducted to depths corresponding to 1.5-3.2 GPa, over a range of peak temperatures of 350-600°C, and are associated with HP/UHP-metamorphosed Jurassic ophiolitic rocks [Agard et al. (2001), Bull. soc. geol. France; Frezzotti et al. (2011), Nature Geoscience]. These metasedimentary suites are composed of interlayered metapelites and metacarbonates and represent a range of peak P-T conditions experienced in modern, relatively cool subduction zones. Integrated petrologic and isotopic study of these rocks allows an analysis of decarbonation and isotopic exchange among oxidized and reduced C reservoirs along prograde subduction-zone P-T paths. Petrographic work on Schistes Lustres metacarbonates indicates only minor occurrences of calc-silicate phases, consistent with the rocks having experienced only very minor decarbonation during prograde metamorphism. Carbonate δ13CVPDB values (-1.5 to 1‰) are similar to values typical of marine carbonates. Higher grade, UHP-metamorphosed carbonates at Cignana show mineralogic evidence of decarbonation; however, the δ13C of the calcite in these samples remains similar to that of marine carbonate. With increasing grade, metapelitic carbonaceous matter shows an increase in δ13CVPDB, ranging from about -25‰ in low-grade Schistes Lustres samples to -16‰ in the highest-grade Cignana samples. Carbonate in the entire suite shows decrease in δ18OSMOW, from marine carbonate values > 25‰ to values of 17-22‰ independent of the carbonate content of the rocks. This shift could possibly be explained by isotopic exchange with silicate phases in the same rocks [Henry et al. (1996), Chem. Geol.]. Metapelitic rocks in this suite experienced moderate amounts of dehydration (20-50%) largely related to breakdown of chlorite and carpholite [Bebout et al. (in press), Chem. Geol. (abstract in this session); Angiboust and Agard (2010), Lithos], conceivably providing a source for infiltrating H2O-rich fluids producing negative shifts in calcite δ18O in interlayered metacarbonates. These results indicate that relatively little decarbonation occurred in carbonate-bearing sediments subducted to depths greater than 100 km, arguing against any model of extensive decarbonation driven by infiltration of the sediments by H2O-rich fluids released from mafic and ultramafic parts of the underlying subducting slab. This study provides field evidence for the efficient retention of C in subducting shale-carbonate sequences through forearc depths, potentially affecting the C budget and isotopic evolution of the deeper mantle.

Intra-slab COH fluid fluxes evidenced by fluid-mediated decarbonation of lawsonite eclogite-facies altered oceanic metabasalts

NASA Astrophysics Data System (ADS)

Vitale Brovarone, Alberto; Chu, Xu; Martin, Laure; Ague, Jay J.; Monié, Patrick; Groppo, Chiara; Martinez, Isabelle; Chaduteau, Carine

2018-04-01

The interplay between the processes controlling the mobility of H2O and C-bearing species during subduction zone metamorphism exerts a critical control on plate tectonics and global volatile recycling. Here we present the first study on fresh, carbonate-bearing, lawsonite eclogite-facies metabasalts from Alpine Corsica, France, which reached the critical depths at which important devolatilization reactions occur in subducting slabs. The studied samples indicate that the evolution of oceanic crustal sequences subducted under present-day thermal regimes is dominated by localized fluid-rock interactions that are strongly controlled by the nature and extent of inherited (sub)seafloor hydrothermal processes, and by the possibility of deep fluids to be channelized along inherited or newly-formed discontinuities. Fluid channelization along inherited discontinuities controlled local rehydration and dehydration/decarbonation reactions and the stability of carbonate and silicate minerals at the blueschist-eclogite transition. Fluid-mediated decarbonation was driven by upward, up-temperature fluid flow in the inverted geothermal gradient of a subducting oceanic slab, a process that has not been documented in natural samples to date. We estimate that the observed fluid-rock reactions released 20-60 kg CO2 per m3 of rock (i.e. 0.7-2.1 wt% CO2), which is in line with the values predicted from decarbonation of metabasalts in open systems at these depths. Conversely, the estimated time-integrated fluid fluxes (20-50 t/m2) indicate that the amount of carbon transported by channelized fluid flow within the volcanic part of subducting oceanic plates is potentially much higher than previous numerical estimates, testifying to the percolation of C-bearing fluids resulting from devolatilization/dissolution processes operative in large reservoirs.

Penetration of hydrogen-based energy system and its potential for causing global environmental change: Scoping risk analysis based on life cycle thinking

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

Kikuchi, Ryunosuke

2006-03-15

A hydrogen-based economy seems superficially to be environmentally friendly, and many people have worked toward its realization. Today hydrogen is mainly produced by decarbonizing fossil fuels (e.g. natural gas), and in the future decarbonization of both fossil fuels and biomass will play a leading role in the production of hydrogen. The main purpose of this paper is to suggest the identification of potential environmental risks in terms of 'life cycle thinking' (which considers all aspects from production to utilization) with regard to the hydrogen-based economy to come. Hydrogen production by decarbonization results in CO{sub 2} emissions. The final destination ofmore » the recovered CO{sub 2} is uncertain. Furthermore, there is a possibility that hydrogen molecules will escape to the atmosphere, posing risks that could occasion global environmental changes such as depletion of stratospheric ozone, temperature change in the stratosphere and change of the hydrides cycle through global vaporization. Based on the results of simulation, requirements regarding the following items are proposed to minimize potential risks: hydrogen source, production and storage loss.« less

Mantle wedge infiltrated with saline fluids from dehydration and decarbonation of subducting slab

PubMed Central

Kawamoto, Tatsuhiko; Yoshikawa, Masako; Kumagai, Yoshitaka; Mirabueno, Ma. Hannah T.; Okuno, Mitsuru; Kobayashi, Tetsuo

2013-01-01

Slab-derived fluids play an important role in heat and material transfer in subduction zones. Dehydration and decarbonation reactions of minerals in the subducting slab have been investigated using phase equilibria and modeling of fluid flow. Nevertheless, direct observations of the fluid chemistry and pressure–temperature conditions of fluids are few. This report describes CO2-bearing saline fluid inclusions in spinel-harzburgite xenoliths collected from the 1991 Pinatubo pumice deposits. The fluid inclusions are filled with saline solutions with 5.1 ± 1.0% (wt) NaCl-equivalent magnesite crystals, CO2-bearing vapor bubbles, and a talc and/or chrysotile layer on the walls. The xenoliths contain tremolite amphibole, which is stable in temperatures lower than 830 °C at the uppermost mantle. The Pinatubo volcano is located at the volcanic front of the Luzon arc associated with subduction of warm oceanic plate. The present observation suggests hydration of forearc mantle and the uppermost mantle by slab-derived CO2-bearing saline fluids. Dehydration and decarbonation take place, and seawater-like saline fluids migrate from the subducting slab to the mantle wedge. The presence of saline fluids is important because they can dissolve more metals than pure H2O and affect the chemical evolution of the mantle wedge. PMID:23716664

Mantle wedge infiltrated with saline fluids from dehydration and decarbonation of subducting slab.

PubMed

Kawamoto, Tatsuhiko; Yoshikawa, Masako; Kumagai, Yoshitaka; Mirabueno, Ma Hannah T; Okuno, Mitsuru; Kobayashi, Tetsuo

2013-06-11

Slab-derived fluids play an important role in heat and material transfer in subduction zones. Dehydration and decarbonation reactions of minerals in the subducting slab have been investigated using phase equilibria and modeling of fluid flow. Nevertheless, direct observations of the fluid chemistry and pressure-temperature conditions of fluids are few. This report describes CO2-bearing saline fluid inclusions in spinel-harzburgite xenoliths collected from the 1991 Pinatubo pumice deposits. The fluid inclusions are filled with saline solutions with 5.1 ± 1.0% (wt) NaCl-equivalent magnesite crystals, CO2-bearing vapor bubbles, and a talc and/or chrysotile layer on the walls. The xenoliths contain tremolite amphibole, which is stable in temperatures lower than 830 °C at the uppermost mantle. The Pinatubo volcano is located at the volcanic front of the Luzon arc associated with subduction of warm oceanic plate. The present observation suggests hydration of forearc mantle and the uppermost mantle by slab-derived CO2-bearing saline fluids. Dehydration and decarbonation take place, and seawater-like saline fluids migrate from the subducting slab to the mantle wedge. The presence of saline fluids is important because they can dissolve more metals than pure H2O and affect the chemical evolution of the mantle wedge.

Tuning Organic Carbon Dioxide Absorbents for Carbonation and Decarbonation

PubMed Central

Rajamanickam, Ramachandran; Kim, Hyungsoo; Park, Ji-Woong

2015-01-01

The reaction of carbon dioxide with a mixture of a superbase and alcohol affords a superbase alkylcarbonate salt via a process that can be reversed at elevated temperatures. To utilize the unique chemistry of superbases for carbon capture technology, it is essential to facilitate carbonation and decarbonation at desired temperatures in an easily controllable manner. Here, we demonstrate that the thermal stabilities of the alkylcarbonate salts of superbases in organic solutions can be tuned by adjusting the compositions of hydroxylic solvent and polar aprotic solvent mixtures, thereby enabling the best possible performances to be obtained from the various carbon dioxide capture agents based on these materials. The findings provides valuable insights into the design and optimization of organic carbon dioxide absorbents. PMID:26033537

Mitigation: Decarbonization unique to cities

NASA Astrophysics Data System (ADS)

Ibrahim, Nadine

2017-10-01

Strategies that reduce fossil-fuel use can achieve both global carbon mitigation and local health-protection goals. Now research shows the dual benefits of compact urban design and circular economy policies in Chinese cities.

40 CFR 86.428-80 - Maintenance, scheduled; test vehicles.

Code of Federal Regulations, 2011 CFR

2011-07-01

... necessary. For example, piston and cylinder replacement caused by piston seizure which results in the vehicle being inoperative; or in the case of two-stroke engines, decarbonization, the need for which is...

40 CFR 86.428-80 - Maintenance, scheduled; test vehicles.

Code of Federal Regulations, 2012 CFR

2012-07-01

... necessary. For example, piston and cylinder replacement caused by piston seizure which results in the vehicle being inoperative; or in the case of two-stroke engines, decarbonization, the need for which is...

40 CFR 86.428-80 - Maintenance, scheduled; test vehicles.

Code of Federal Regulations, 2010 CFR

2010-07-01

... necessary. For example, piston and cylinder replacement caused by piston seizure which results in the vehicle being inoperative; or in the case of two-stroke engines, decarbonization, the need for which is...

40 CFR 86.428-80 - Maintenance, scheduled; test vehicles.

Code of Federal Regulations, 2014 CFR

2014-07-01

... necessary. For example, piston and cylinder replacement caused by piston seizure which results in the vehicle being inoperative; or in the case of two-stroke engines, decarbonization, the need for which is...

Slip stream apparatus and method for treating water in a circulating water system

DOEpatents

Cleveland, J.R.

1997-03-18

An apparatus is described for treating water in a circulating water system that has a cooling water basin which includes a slip stream conduit in flow communication with the circulating water system, a source of acid solution in flow communication with the slip stream conduit, and a decarbonator in flow communication with the slip stream conduit and the cooling water basin. In use, a slip stream of circulating water is drawn from the circulating water system into the slip stream conduit of the apparatus. The slip stream pH is lowered by contact with an acid solution provided from the source thereof. The slip stream is then passed through a decarbonator to form a treated slip stream, and the treated slip stream is returned to the cooling water basin. 4 figs.

The roles of users in shaping transitions to new energy systems

NASA Astrophysics Data System (ADS)

Schot, Johan; Kanger, Laur; Verbong, Geert

2016-05-01

Current government information policies and market-based instruments aimed at influencing the energy choices of consumers often ignore the fact that consumer behaviour is not fully reducible to individuals making rational conscious decisions all the time. The decisions of consumers are largely configured by shared routines embedded in socio-technical systems. To achieve a transition towards a decarbonized and energy-efficient system, an approach that goes beyond individual consumer choice and puts shared routines and system change at its centre is needed. Here, adopting a transitions perspective, we argue that consumers should be reconceptualized as users who are important stakeholders in the innovation process shaping new routines and enacting system change. We review the role of users in shifts to new decarbonized and energy-efficient systems and provide a typology of user roles.

Long-term energy security in a national scale using LEAP. Application to de-carbonization scenarios in Andorra

NASA Astrophysics Data System (ADS)

Travesset-Baro, Oriol; Jover, Eric; Rosas-Casals, Marti

2016-04-01

This paper analyses the long-term energy security in a national scale using Long-range Energy Alternatives Planning System (LEAP) modelling tool. It builds the LEAP Andorra model, which forecasts energy demand and supply for the Principality of Andorra by 2050. It has a general bottom-up structure, where energy demand is driven by the technological composition of the sectors of the economy. The technological model is combined with a top-down econometric model to take into account macroeconomic trends. The model presented in this paper provides an initial estimate of energy demand in Andorra segregated into all sectors (residential, transport, secondary, tertiary and public administration) and charts a baseline scenario based on historical trends. Additional scenarios representing different policy strategies are built to explore the country's potential energy savings and the feasibility to achieve the Intended Nationally Determined Contribution (INDC) submitted in April 2015 to UN. In this climatic agreement Andorra intends to reduce net greenhouse gas emissions (GHG) by 37% as compared to a business-as-usual scenario by 2030. In addition, current and future energy security is analysed in this paper under baseline and de-carbonization scenarios. Energy security issues are assessed in LEAP with an integrated vision, going beyond the classic perspective of security of supply, and being closer to the sustainability's integrative vision. Results of scenarios show the benefits of climate policies in terms of national energy security and the difficulties for Andorra to achieving the de-carbonization target by 2030.

Impact melting of carbonates from the Chicxulub crater

NASA Astrophysics Data System (ADS)

Jones, A. P.; Claeys, P.; Heuschkel, S.

We have recently interpreted distinctive feathery-textured spinifex carbonate in the upper part of the Chicxulub suevite breccia as quenched carbonate melts (Jones et al. 1998); these distinctive fragments make up to 10 vol% of the breccia. Carbonate clasts and spherules occurring in the ejecta-rich basal part of the coarse clastic sequence, which marks the K/T boundary all around the Gulf of Mexico, may represent distal quenched droplets of carbonate liquids. In seeking to explain this widespread carbonate impact-melting phenomenon, we have re-examined the available experimental evidence. The important decarbonation reaction for calcite CaCO3=CaO+CO2 is inhibited by very small pressures up to temperatures >2000 K. We conclude that massive decarbonation by direct shock pressure is unlikely without attainment of temperatures >4000 K. Therefore, decarbonation generally can only occur during post-shock cooling for carbonates at low pressure (< 10 bars). We assume that post-shock cooling is quasi-thermodynamic, and provide a general P-T model for carbonate spanning 11 orders of magnitude in pressure (atmosphere to core). Subtle differences in sample preconditioning can probably explain the wildly divergent experimental shock data. A major planetary implication for the formation of the Earth's early atmosphere is that impacts on limestone would be less likely to have contributed substantial CO2 than has previously been assumed. Lastly, we note that carbonate melts at high pressures serve as excellent catalysts for diamond growth, and may have contributed to the widespread formation of some impact diamond.

The role of capital costs in decarbonizing the electricity sector

NASA Astrophysics Data System (ADS)

Hirth, Lion; Steckel, Jan Christoph

2016-11-01

Low-carbon electricity generation, i.e. renewable energy, nuclear power and carbon capture and storage, is more capital intensive than electricity generation through carbon emitting fossil fuel power stations. High capital costs, expressed as high weighted average cost of capital (WACC), thus tend to encourage the use of fossil fuels. To achieve the same degree of decarbonization, countries with high capital costs therefore need to impose a higher price on carbon emissions than countries with low capital costs. This is particularly relevant for developing and emerging economies, where capital costs tend to be higher than in rich countries. In this paper we quantitatively evaluate how high capital costs impact the transformation of the energy system under climate policy, applying a numerical techno-economic model of the power system. We find that high capital costs can significantly reduce the effectiveness of carbon prices: if carbon emissions are priced at USD 50 per ton and the WACC is 3%, the cost-optimal electricity mix comprises 40% renewable energy. At the same carbon price and a WACC of 15%, the cost-optimal mix comprises almost no renewable energy. At 15% WACC, there is no significant emission mitigation with carbon pricing up to USD 50 per ton, but at 3% WACC and the same carbon price, emissions are reduced by almost half. These results have implications for climate policy; carbon pricing might need to be combined with policies to reduce capital costs of low-carbon options in order to decarbonize power systems.

Emerging clean energy technology investment trends

NASA Astrophysics Data System (ADS)

Bumpus, A.; Comello, S.

2017-06-01

Early-stage capital providers and clean energy technology incubators are supporting a new wave of innovations focused on end-use efficiency and demand control. This wave complements expanding investments in supply technologies required for electricity sector decarbonization.

Slip stream apparatus and method for treating water in a circulating water system

DOEpatents

Cleveland, Joe R.

1997-01-01

An apparatus (10) for treating water in a circulating water system (12) t has a cooling water basin (14) includes a slip stream conduit (16) in flow communication with the circulating water system (12), a source (36) of acid solution in flow communication with the slip stream conduit (16), and a decarbonator (58) in flow communication with the slip stream conduit (16) and the cooling water basin (14). In use, a slip stream of circulating water is drawn from the circulating water system (12) into the slip stream conduit (16) of the apparatus (10). The slip stream pH is lowered by contact with an acid solution provided from the source (36) thereof. The slip stream is then passed through a decarbonator (58) to form a treated slip stream, and the treated slip stream is returned to the cooling water basin (14).

Energy [R]Evolution: Opportunities for Decarbonizing Canada

NASA Astrophysics Data System (ADS)

Byrne, J. M.

2016-12-01

The future of conventional energy in Canada is uncertain. World oil prices have suffered steep declines recently and there are no strong arguments for recovery in the foreseeable future. The country is now engaged in serious debates and discussions over the value of GHG emissions, pipelines, oil and gas operations, and renewable energy. Oilsands deposits in northern Alberta require long-term investment and decades of consistent sales to repay those investments. The election of more progressive governments in Alberta and Canada may provide the national and global credibility and opportunity to address the environmental problems caused by Oilsands and other fossil fuel developments. The discussion will focus on the possible ways forward for Canada to diversify the regional and national economy with renewable energy networks, thereby meeting our Paris GHG emission reduction commitments. The end goal of this work is to see the Canadian economy decarbonized within two decades.

Thermal decomposition of dolomite under CO2: insights from TGA and in situ XRD analysis.

PubMed

Valverde, Jose Manuel; Perejon, Antonio; Medina, Santiago; Perez-Maqueda, Luis A

2015-11-28

Thermal decomposition of dolomite in the presence of CO2 in a calcination environment is investigated by means of in situ X-ray diffraction (XRD) and thermogravimetric analysis (TGA). The in situ XRD results suggest that dolomite decomposes directly at a temperature around 700 °C into MgO and CaO. Immediate carbonation of nascent CaO crystals leads to the formation of calcite as an intermediate product of decomposition. Subsequently, decarbonation of this poorly crystalline calcite occurs when the reaction is thermodynamically favorable and sufficiently fast at a temperature depending on the CO2 partial pressure in the calcination atmosphere. Decarbonation of this dolomitic calcite occurs at a lower temperature than limestone decarbonation due to the relatively low crystallinity of the former. Full decomposition of dolomite leads also to a relatively low crystalline CaO, which exhibits a high reactivity as compared to limestone derived CaO. Under CO2 capture conditions in the Calcium-Looping (CaL) process, MgO grains remain inert yet favor the carbonation reactivity of dolomitic CaO especially in the solid-state diffusion controlled phase. The fundamental mechanism that drives the crystallographic transformation of dolomite in the presence of CO2 is thus responsible for its fast calcination kinetics and the high carbonation reactivity of dolomitic CaO, which makes natural dolomite a potentially advantageous alternative to limestone for CO2 capture in the CaL technology as well as SO2in situ removal in oxy-combustion fluidized bed reactors.

Evidence and future scenarios of a low-carbon energy transition in Central America: a case study in Nicaragua

NASA Astrophysics Data System (ADS)

Barido, Diego Ponce de Leon; Johnston, Josiah; Moncada, Maria V.; Callaway, Duncan; Kammen, Daniel M.

2015-10-01

The global carbon emissions budget over the next decades depends critically on the choices made by fast-growing emerging economies. Few studies exist, however, that develop country-specific energy system integration insights that can inform emerging economies in this decision-making process. High spatial- and temporal-resolution power system planning is central to evaluating decarbonization scenarios, but obtaining the required data and models can be cost prohibitive, especially for researchers in low, lower-middle income economies. Here, we use Nicaragua as a case study to highlight the importance of high-resolution open access data and modeling platforms to evaluate fuel-switching strategies and their resulting cost of power under realistic technology, policy, and cost scenarios (2014-2030). Our results suggest that Nicaragua could cost-effectively achieve a low-carbon grid (≥80%, based on non-large hydro renewable energy generation) by 2030 while also pursuing multiple development objectives. Regional cooperation (balancing) enables the highest wind and solar generation (18% and 3% by 2030, respectively), at the least cost (US127 MWh-1). Potentially risky resources (geothermal and hydropower) raise system costs but do not significantly hinder decarbonization. Oil price sensitivity scenarios suggest renewable energy to be a more cost-effective long-term investment than fuel oil, even under the assumption of prevailing cheap oil prices. Nicaragua’s options illustrate the opportunities and challenges of power system decarbonization for emerging economies, and the key role that open access data and modeling platforms can play in helping develop low-carbon transition pathways.

Anticipating the Environmental Impacts and Behavioral Drivers of Deep Decarbonization

EPA Pesticide Factsheets

EPA is seeking regular and early career applications proposing research that will contribute to an improved ability to understand and anticipate the public health and environmental impacts and behavioral drivers of significant changes in energy consumption

City transformations in a 1.5 °C warmer world

NASA Astrophysics Data System (ADS)

Solecki, William; Rosenzweig, Cynthia; Dhakal, Shobhakar; Roberts, Debra; Barau, Aliyu Salisu; Schultz, Seth; Ürge-Vorsatz, Diana

2018-03-01

Meeting the ambitions of the Paris Agreement will require rapid and massive decarbonization of cities, as well as adaptation. Capacity and requirement differs across cities, with challenges and opportunities for transformational action in both the Global North and South.

Turning Paris into reality at the University of California

NASA Astrophysics Data System (ADS)

Victor, David G.; Abdulla, Ahmed; Auston, David; Brase, Wendell; Brouwer, Jack; Brown, Karl; Davis, Steven J.; Kappel, Carrie V.; Meier, Alan; Modera, Mark; Zarin Pass, Rebecca; Phillips, David; Sager, Jordan; Weil, David; TomKat Natural Gas Exit Strategies Working Group

2018-03-01

The Paris Agreement highlights the need for local climate leadership. The University Of California's approach to deep decarbonization offers lessons in efficiency, alternative fuels and electrification. Bending the emissions curve globally requires efforts that blend academic insights with practical solutions.

City Transformations in a 1.5 C Warmer World

NASA Technical Reports Server (NTRS)

Barau, Aliyu Salisu; Urge-Vorsatz, Diana; Schultz, Seth; Solecki, William; Dhakal, Shobhakar; Rosenzweig, Cynthia; Roberts, Debra

2018-01-01

Meeting the ambitions of the Paris Agreement will require rapid and massive decarbonization of cities, as well as adaptation. Capacity and requirement differs across cities, with challenges and opportunities for transformational action in both the Global North and South.

Decarbonizing the Global Economy - An Integrated Assessment of Low Carbon Emission Scenarios proposed in Climate Policy

NASA Astrophysics Data System (ADS)

Hokamp, Sascha; Khabbazan, Mohammad Mohammadi

2017-04-01

In 2015, the Conference of the Parties (COP 21) reaffirmed to targeting the global mean temperature rise below 2 °C in 2100 while finding no consent on decarbonizing the global economy, and instead, the final agreement called for enhanced scientific investigation of low carbon emission scenarios (UNFCC, 2015). In addition, the Climate Action Network International (CAN) proposes Special Reports to address decarbonization and low carbon development including 1.5 °C scenarios (IPCC, 2016). In response to these developments, we investigate whether the carbon emission cuts, in accordance with the recent climate policy proposals, may reach the climate target. To tackle this research question, we employ the coupled climate-energy-economy integrated assessment Model of INvestment and endogenous technological Development (MIND, cf. Edenhofer et al., 2005, Neubersch et al. 2014). Extending MIND's climate module to the two-box version used in the Dynamic Integrated model of Climate and the Economy (DICE, cf. Nordhaus and Sztorc, 2013, Nordhaus 2014), we perform a cost-effectiveness analysis with constraints on anthropogenic carbon emissions. We show that a climate policy scenario with early decarbonization complies with the 2° C climate target, even without Carbon Capturing and Storage (CCS) or negative emissions (see van Vuuren et al., 2013, for negative emissions). However, using emission inertia of 3.7 percent annually, reflecting the inflexibility on transforming the energy sector, we find a climate policy with moderately low emissions from 2100 onwards at a cost in terms of Balanced Growth Equivalents (BGE, cf. Anthoff and Tol, 2009) of 0.764 % that requires an early (2035 vs. 2120) peak of investments in renewable energy production compared to a business-as-usual scenario. Hence, decarbonizing the global economy and achieving the 2 °C target might still be possible before 2100, but the window of opportunity is beginning to close. References: Anthoff, D., and Tol, R. S. J. (2009), "The Impact of Climate Change on the Balanced Growth Equivalent: An Application to FUND", Environmental and Resource Economics, 43 (3), 351-367. Edenhofer, O., Bauer, N., and Kriegler, E. (2005), "The Impact of Technological Change on Climate Protection and Welfare: Insights from the Model MIND", Ecological Economics, 54, 277-292. Neubersch, D., Held, H., and Otto, A., (2014), "Operationalizing Climate Targets under Learning: An Application of Cost-Risk Analysis", Climatic Change, 126, 305-318. Nordhaus, W. D., and Sztorc, P., (2013), DICE2013R: Introduction and User's Manual Nordhaus, W. D. (2014), "Estimates of the Social Cost of Carbon: Concepts and Results from the DICE-2013R Model and Alternative Approaches", Journal of the Association of Environmental and Resource Economists, 1 (1/2, Spring/Summer, 2014), 273-312. IPCC (2016), Sixth Assessment Report (AR6) Products, IPCC-XLIII/INF.7. UNFCCC (2015), Adoption of the Paris Agreement van Vuuren, D. P., Deetman, S., van Vliet, J., van den Berg, M. , van Ruijven, B.J., and Koelbl, B. (2013): "The Role of Negative CO2 Emissions for Reaching 2 °C - Insights from Integrated Assessment Modelling", Climatic Change, 118, 15-27.

Steady- and non-steady-state carbonate-silicate controls on atmospheric CO2

USGS Publications Warehouse

Sundquist, E.T.

1991-01-01

Two contrasting hypotheses have recently been proposed for the past long-term relation between atmospheric CO2 and the carbonate-silicate geochemical cycle. One approach (Berner, 1990) suggests that CO2 levels have varied in a manner that has maintained chemical weathering and carbonate sedimentation at a steady state with respect to tectonically controlled decarbonation reactions. A second approach (Raymo et al., 1988), applied specificlly to the late Cenozoic, suggests a decrease in CO2 caused by an uplift-induced increase in chemical weathering, without regard to the rate of decarbonation. According to the steady-state (first) hypothesis, increased weathering and carbonate sedimentation are generally associated with increasing atmospheric CO2, whereas the uplift (second) hypothesis implies decreasing CO2 under the same conditions. An ocean-atmosphere-sediment model has been used to assess the response of atmospheric CO2 and carbonate sedimentation to global perturbations in chemical weathering and decarbonation reactions. Although this assessment is theoretical and cannot yet be related to the geologic record, the model simulations compare steady-state and non-steady-state carbonate-silicate cycle response. The e-fold response time of the 'CO2-weathering' feedback mechanism is between 300 and 400 ka. The response of carbonate sedimentation is much more rapid. These response times provide a measure of the strength of steady-state assumptions, and imply that certain systematic relations are sustained throughout steady-state and non-steady-state scenarios for the carbonate-silicate cycle. The simulations suggest that feedbacks can maintain the system near a steady state, but that non-steady-state effects may contribute to long-term trends. The steady-state and uplift hypotheses are not necessarily incompatible over time scales of a few million years. ?? 1991.

Fatty acids in sparry calcite fracture fills and microsparite cement of septarian diagenetic concretions

NASA Astrophysics Data System (ADS)

Pearson, M. J.; Hendry, J. P.; Taylor, C. W.; Russell, M. A.

2005-04-01

Sparry calcite fracture fills and concretion body cements in concretions from the Flodigarry Shale Member of the Staffin Shale Formation, Isle of Skye, Scotland, entrap and preserve mineral and organic materials of sedimentary and diagenetic origin. Fatty acids are a major component of the lipids recovered by decarbonation and comprise mainly n-alkanoic and α-ω dicarboxylic acids. Two generations of fracture-fill calcite (early brown and later yellow) and the concretion body microspar yield significantly different fatty acid profiles. Early brown calcites yield mainly medium-chain n-alkanoic acids with strong even predominance; later yellow calcites are dominated by α-ω dicarboxylic acids with no even predominance. Both fracture fills lack the long-chain n-alkanoic and α-ω dicarboxylic acids additionally recovered from the concretion bodies. The absence of longer chain acids in the calcite spar fracture fills is inferred to result from the transport of fatty acids by septarian mineralising fluids whereby low-aqueous solubility of longer chain acids or their salts accounts for their relative immobility. Comparative experiments have been carried out using conventional solvent extraction on the concretion body and associated shales, both decarbonated and untreated. Extracted lipid yields are higher, but the fatty acids probably derive from mixed locations in the rock including both kerogen- and carbonate-associated lipid pools. Only experiments involving decarbonation yielded α-ω dicarboxylic acids in molecular distributions probably controlled mainly by fluid transport. Alkane biomarker ratios indicate very low thermal maturity has been experienced by the concretions and their host sediments. Septarian cracks lined by brown calcite formed during early burial. Microbial CO 2 from sulphate-reducing bacteria was probably the main source of mineralising carbonate. Emplacement of the later septarian fills probably involved at least one episode of fluid invasion.

Political economy of Clinton's ambitious energy program

NASA Astrophysics Data System (ADS)

Aldy, Joseph E.

2016-10-01

Hillary Clinton's campaign has stressed her continuity with Obama's energy policy on key aspects such as decarbonization of the US economy, technological innovation and global cooperation. However, policy reforms to deliver long-term climate goals might be out of reach in a highly divided Congress.

Potential for widespread electrification of personal vehicle travel in the United States

NASA Astrophysics Data System (ADS)

Needell, Zachary A.; McNerney, James; Chang, Michael T.; Trancik, Jessika E.

2016-09-01

Electric vehicles can contribute to climate change mitigation if coupled with decarbonized electricity, but only if vehicle range matches travellers’ needs. Evaluating electric vehicle range against a population’s needs is challenging because detailed driving behaviour must be taken into account. Here we develop a model to combine information from coarse-grained but expansive travel surveys with high-resolution GPS data to estimate the energy requirements of personal vehicle trips across the US. We find that the energy requirements of 87% of vehicle-days could be met by an existing, affordable electric vehicle. This percentage is markedly similar across diverse cities, even when per capita gasoline consumption differs significantly. We also find that for the highest-energy days, other vehicle technologies are likely to be needed even as batteries improve and charging infrastructure expands. Car sharing or other means to serve this small number of high-energy days could play an important role in the electrification and decarbonization of transportation.

"Decarbonization" of an imino N-heterocyclic carbene via triple benzyl migration from hafnium

USDA-ARS?s Scientific Manuscript database

An imino N-heterocyclic carbene underwent three sequential benzyl migrations upon reaction with tetrabenzylhafnium, resulting in complete removal of the carbene carbon from the ligand. The resulting eneamido-amidinato hafnium complex showed alkene polymerization activity comparable to that of a prec...

Extensive decarbonation of continuously hydrated subducting slabs

NASA Astrophysics Data System (ADS)

Arzilli, F.; Burton, M. R.; La Spina, G.; Macpherson, C.

2016-12-01

CO2 release from subducting slabs is a key element of Earth's carbon cycle, consigning slab carbon either to mantle burial or recycling to the surface through arc volcanism, however, what controls subducted carbon's fate is poorly understood. Fluids mobilized by devolatilization of subducting slabs play a fundamental role in the melting of mantle wedges and in global geochemical cycles [1]. The effect of such fluids on decarbonation in subducting lithologies has been investigated recently [2-5] but mechanisms of carbon transfer from the slab to wedge are poorly understood [2-6]. Several thermodynamic models [2-3], and experimental studies [6] suggest that carbon-bearing phases are stable at sub-arc depths (80-140 km; 2.6-4.5 GPa), implying that this carbon can be subducted to mantle depths of >140 km. This is inconsistent with observations of voluminous CO2 release from arc volcanoes [7-10], located above slabs that are at 2.6-4.5 GPa pressure. Here, we show that continuous hydrated of sediment veneers on subducting slabs by H2O released from oceanic crust and serpentinised mantle lithosphere [11-13], produces extensive slab decarbonation over a narrow, sub-arc pressure range, even for low temperature subduction pathways. This explains the location of CO2-rich volcanism, quantitatively links the sedimentary composition of slab material to the degree of decarbonation and greatly increases estimates for the magnitude of carbon flux through the arc in subduction zones. [1] Hilton, D.R. et al. (2002) Rev. Mineral. Geochem. 47, 319-370. [2] Gorman, P.J. et al. (2006) Geochem. Geophys. Geosyst. 7. [3] Kerrick, D.M. and Connolly, J.A.D. (2001) Nature 411, 293-296. [4] Cook-Kollars, J. et al. (2014) Chem. Geol. 386, 31-48. [5] Collins, N.C. et al. (2015) Chem. Geol. 412, 132-150. [6] Poli, S. et al. (2009) Earth Planet. Sci. Lett. 278, 350-360. [7] Sano, Y. and Williams, S.N. (1996) Geophys. Res. Lett. 23, 2749-2752. [8] Marty, B. and Tolstikhin, I.N. (1998) Chem. Geol. 145, 233-248. [9] Wallace, P.J. (2005) J. Volcanol. Geoth. Res. 140, 217-240. [10] Burton, M.R. et al. (2013) Rev. Mineral. Geochem. 75, 323-354. [11] Ulmer, P. and Trommsdorff, V. (1995) Science 268, 858-861. [12] Schmidt, M.W. and Poli, S. (1998) Earth Planet. Sci. Lett. 163, 361-379. [13] van Keken, P. E. et al. (2011) J. Geophys. Res. 116.

SWITCH-China: A Systems Approach to Decarbonizing China's Power System.

PubMed

He, Gang; Avrin, Anne-Perrine; Nelson, James H; Johnston, Josiah; Mileva, Ana; Tian, Jianwei; Kammen, Daniel M

2016-06-07

We present an integrated model, SWITCH-China, of the Chinese power sector with which to analyze the economic and technological implications of a medium to long-term decarbonization scenario while accounting for very-short-term renewable variability. On the basis of the model and assumptions used, we find that the announced 2030 carbon peak can be achieved with a carbon price of ∼$40/tCO2. Current trends in renewable energy price reductions alone are insufficient to replace coal; however, an 80% carbon emission reduction by 2050 is achievable in the Intergovernmental Panel on Climate Change Target Scenario with an optimal electricity mix in 2050 including nuclear (14%), wind (23%), solar (27%), hydro (6%), gas (1%), coal (3%), and carbon capture and sequestration coal energy (26%). The co-benefits of carbon-price strategy would offset 22% to 42% of the increased electricity costs if the true cost of coal and the social cost of carbon are incorporated. In such a scenario, aggressive attention to research and both technological and financial innovation mechanisms are crucial to enabling the transition at a reasonable cost, along with strong carbon policies.

The Road Less Travelled: The Deep Challenges of Social Transformations

NASA Astrophysics Data System (ADS)

O'Brien, K. L.; Moser, S. C.

2016-12-01

How do we create the societal transformations necessary to stabilize the global climate and address other global goals? The roadmap metaphor guiding this session reflects a managerial approach to deep decarbonization, one that can be planned, charted, guided and implemented with the tools already known. Transformations and systems change involve far more than technical innovations, policy instruments and behavioral change. Drawing on a wide range of research on transformation processes from the social sciences and humanities and systems science, we argue that current approaches to decarbonization are likely to fail if they ignore theories of social change, including insights on the dynamics of social, cultural, economic and political transformations. Climate stabilization also calls for attention to the relationships between human values, political agency, power, and institutional change. It is precisely these deeper dynamics - which are typically ignored - that stall transformative change. Rather than developing a carbon road map, we suggest both a wider and deeper exploration of the territory of social transformation is needed, and suggest both different metaphors and methods to engage individual change agents and communities of actors, who together can create pathways to sustainability.

Energy storage deployment and innovation for the clean energy transition

NASA Astrophysics Data System (ADS)

Kittner, Noah; Lill, Felix; Kammen, Daniel M.

2017-09-01

The clean energy transition requires a co-evolution of innovation, investment, and deployment strategies for emerging energy storage technologies. A deeply decarbonized energy system research platform needs materials science advances in battery technology to overcome the intermittency challenges of wind and solar electricity. Simultaneously, policies designed to build market growth and innovation in battery storage may complement cost reductions across a suite of clean energy technologies. Further integration of R&D and deployment of new storage technologies paves a clear route toward cost-effective low-carbon electricity. Here we analyse deployment and innovation using a two-factor model that integrates the value of investment in materials innovation and technology deployment over time from an empirical dataset covering battery storage technology. Complementary advances in battery storage are of utmost importance to decarbonization alongside improvements in renewable electricity sources. We find and chart a viable path to dispatchable US$1 W-1 solar with US$100 kWh-1 battery storage that enables combinations of solar, wind, and storage to compete directly with fossil-based electricity options.

Carbon Mobility at Subduction Interfaces via Deformation-Enhanced Fluid Infiltration: Evidence from the Swiss/Italian Alps

NASA Astrophysics Data System (ADS)

Jaeckel, K. P.; Bebout, G. E.; Angiboust, S.

2016-12-01

The interplay between fluid flow and deformation along subduction interfaces, and the extent to which deformation-enhanced fluid infiltration can drive decarbonation and carbonate dissolution, remain poorly understood. Recent work on HP/UHP decarbonation in W. Alps suites has indicated that, in intact volumes of metasediment, metabasalt, and ophicarbonate away from major shear zones and with few veins, carbonate is largely retained to 80-90 km depths (Cook-Kollars et al., 2014; Collins et al., 2015; Chem. Geol.). Yet uncertain is whether forearc fluid infiltration focused in intensely sheared and fractured zones could result in greater mobilization of C from subducting sections, in quantities sufficient to impact subduction zone C cycling. Lower-plate rocks at Arosa and Dent Blanche interface exposures (Bachmann et al., 2009, JGR; Angiboust et al., 2015, G3) are primarily calc-schist intercalated with meta-ultramafic and metamafic schist and contain carbonate-bearing veins of varying abundance and texture. At some localities, these sections contain blocks of carbonate, metabasalt, and upper-plate gneiss. Strongly deformed veins concordant with the foliation parallel to the thrust interface commonly contain carbonate and quartz. In highly sheared regions in the Arosa Zone, δ18O(VSMOW) values of some host-rocks and veins are shifted from +20 ± 2‰, values observed regionally for the Schistes Lustres, to values of +11 to +13‰. These shifts can be explained by interaction with externally-derived H2O-rich fluids with δ18O of +9 to +11‰. Smaller datasets for Dent Blanche localities hint at similar δ18O shifts. Most of these rocks contain little evidence of C release by decarbonation reactions. Evidence exists for local-scale dissolution of carbonate, during pressure solution, and carbonate-bearing veins reflect C mobility in fluids. Ongoing work assesses whether volumes of carbonate removed in some regions balance with those precipitated nearby in veins and pressure shadows.

A tale of two cities: Comparison of impacts on CO2 emissions, the indoor environment and health of home energy efficiency strategies in London and Milton Keynes

NASA Astrophysics Data System (ADS)

Shrubsole, C.; Das, P.; Milner, J.; Hamilton, I. G.; Spadaro, J. V.; Oikonomou, E.; Davies, M.; Wilkinson, P.

2015-11-01

Dwellings are a substantial source of global CO2 emissions. The energy used in homes for heating, cooking and running electrical appliances is responsible for a quarter of current total UK emissions and is a key target of government policies for greenhouse gas abatement. Policymakers need to understand the potential impact that such decarbonization policies have on the indoor environment and health for a full assessment of costs and benefits. We investigated these impacts in two contrasting settings of the UK: London, a predominantly older city and Milton Keynes, a growing new town. We employed SCRIBE, a building physics-based health impact model of the UK housing stock linked to the English Housing Survey, to examine changes, 2010-2050, in end-use energy demand, CO2 emissions, winter indoor temperatures, airborne pollutant concentrations and associated health impacts. For each location we modelled the existing (2010) housing stock and three future scenarios with different levels of energy efficiency interventions combined with either a business-as-usual, or accelerated decarbonization of the electricity grid approach. The potential for CO2 savings was appreciably greater in London than Milton Keynes except when substantial decarbonization of the electricity grid was assumed, largely because of the lower level of current energy efficiency in London and differences in the type and form of the housing stock. The average net impact on health per thousand population was greater in magnitude under all scenarios in London compared to Milton Keynes and more beneficial when it was assumed that purpose-provided ventilation (PPV) would be part of energy efficiency interventions, but more detrimental when interventions were assumed not to include PPV. These findings illustrate the importance of considering ventilation measures for health protection and the potential variation in the impact of home energy efficiency strategies, suggesting the need for tailored policy approaches in different locations, rather than adopting a universally rolled out strategy.

Contrasting fluid/rock interaction between the Notch Peak granitic intrusion and argillites and limestones in western Utah: evidence from stable isotopes and phase assemblages

USGS Publications Warehouse

Nabelek, P.I.; Labotka, T.C.; O'Neil, J.R.; Papike, J.J.

1984-01-01

The Jurassic Notch Peak granitic stock, western Utah, discordantly intrudes Cambrian interbedded pure limestones and calcareous argillites. Contact metamorphosed argillite and limestone samples, collected along traverses away from the intrusion, were analyzed for ??18O, ??13C, and ??D. The ??13C and ??18O values for the limestones remain constant at about 0.5 (PDB) and 20 (SMOW), respectively, with increasing metamorphic grade. The whole rock ??18O values of the argillites systematically decrease from 19 to as low as 8.1, and the ??13C values of the carbonate fraction from 0.5 to -11.8. The change in ??13C values can be explained by Rayleigh decarbonation during calcsilicate reactions, where calculated {Mathematical expression} is about 4.5 permil for the high-grade samples and less for medium and low-grade samples suggesting a range in temperatures at which most decarbonation occurred. However, the amount of CO2 released was not anough to decrease the whole rock ??18O to the values observed in the argillites. The low ??18O values close to the intrusion suggest interaction with magmatic water that had a ??18O value of 8.5. The extreme lowering of ??13C by fractional devolatilization and the lowering of ??18O in argillites close to the intrusion indicates oxgen-equivalent fluid/rock ratios in excess of 1.0 and X(CO2)F of the fluid less than 0.2. Mineral assemblages in conjunction with the isotopic data indicate a strong influence of water infiltration on the reaction relations in the argillites and separate fluid and thermal fronts moving thru the argillites. The different stable isotope relations in limestones and argillites attest to the importance of decarbonation in the enhancement of permeability. The flow of fluids was confined to the argillite beds (argillite aquifers) whereas the limestones prevented vertical fluid flow and convective cooling of the stock. ?? 1984 Springer-Verlag.

Decarbonation and carbonation processes in the slab and mantle wedge - insights from thermomechanical modeling

NASA Astrophysics Data System (ADS)

Gonzalez, C. M.; Gorczyk, W.; Connolly, J. A.; Gerya, T.; Hobbs, B. E.; Ord, A.

2013-12-01

Subduction zones offer one of the most geologically active and complex systems to investigate. They initiate a process in which crustal sediments are recycled, mantle heterogeneities arise, and mantle wedge refertilization occurs via slab derived volatiles and magma generation. Slab derived volatiles, consisting primarily of H2O - CO2 fluids, are especially critical in subduction evolution as they rheologically weaken the mantle wedge, decrease solidus temperatures, and rock-fluid interactions result in metasomatism. While the effects of H2O in these processes have been well studied in the past decades, CO2's role remains open for much scientific study. This is partly attributed to the sensitivity of decarbonation to the thermal gradient of the subduction zone, bulk compositions (sediments, basalts, peridotites) and redox state of the mantle. Here we show benchmarking results of a subduction scenario that implements carbonation-decarbonation reactions into a fully coupled petrological-thermomechanical numerical modeling code. We resolve stable mineralogy and extract rock properties via Perple_X at a resolution of 5°C and 25 MPa. The numerical technique employed is a characteristics-based marker-in-cell technique with conservative finite-differences that includes visco-elastic-plastic rheologies (I2ELVIS). The devolatilized fluids are tracked via markers that are either generated or consumed based on P-T conditions. The fluids are also allowed to freely advect within the velocity field. The hosts for CO2 in this system are computed via GLOSS average sediments (H2O: 7.29 wt% & CO2: 3.01 wt%), metabasalts ( H2O: 2.63 & CO2: 2.90 wt%), and ophicarbonates (H2O: 1.98 wt% & CO2: 5.00 wt%). Our results demonstrate the feasibility of applying this decarbonation-carbonation numerical method to a range of geodynamic scenarios that simulate the removal of CO2 from the subducting slab. Such applicable scenarios include sediment diapirism into the convecting wedge and better understanding the fate of carbonates beyond the subarc and consequent subduction into the deeper mantle within a fully coupled model framework. A case study where CO2 fluids are intimately connected to subduction and metasomatism of the mantle is in the Western Mediterranean in Italy. There, carbonate melts metasomatized the asthenosphere leading to a seismic low velocity zone associated with large scale mantle degassing in the region of approximately 70 Mt/year of CO2 [1]. This natural laboratory provides us with a present day example to help constrain the benchmarking process in order to refine our numerical techniques. [1] Frezzotti, Peccerillo, & Panza, 2009. Chemical Geology, 262(1-2), 108-120. doi: DOI 10.1016/j.chemgeo.2009.02.015

Our Transforming Energy Economy: Pathways to a Decarbonized Future -

Science.gov Websites

a clean energy future. For example, JISEA's impacts can be seen in its growing natural gas research example, JISEA hosted the NG-RE 360 Degrees of Opportunity Forum, a series of workshops in different assets are one example, such as "smart" buildings that benefit both from solar photovoltaic

NREL Staff Recognized by DOE for Outstanding Achievements at 2016 Annual

Science.gov Websites

Bryan Pivovar was recognized for his outstanding dedication and contributions in developing the H2 at developing a white paper, demonstrating approaches to deeply decarbonize multiple energy sectors. H2 at Scale commercialized through a tech transfer opportunity, paving the way for U.S. manufacturing leadership. Market

Clean vehicles as an enabler for a clean electricity grid

NASA Astrophysics Data System (ADS)

Coignard, Jonathan; Saxena, Samveg; Greenblatt, Jeffery; Wang, Dai

2018-05-01

California has issued ambitious targets to decarbonize transportation through the deployment of electric vehicles (EVs), and to decarbonize the electricity grid through the expansion of both renewable generation and energy storage. These parallel efforts can provide an untapped synergistic opportunity for clean transportation to be an enabler for a clean electricity grid. To quantify this potential, we forecast the hourly system-wide balancing problems arising out to 2025 as more renewables are deployed and load continues to grow. We then quantify the system-wide balancing benefits from EVs modulating the charging or discharging of their batteries to mitigate renewable intermittency, without compromising the mobility needs of drivers. Our results show that with its EV deployment target and with only one-way charging control of EVs, California can achieve much of the same benefit of its Storage Mandate for mitigating renewable intermittency, but at a small fraction of the cost. Moreover, EVs provide many times these benefits if two-way charging control becomes widely available. Thus, EVs support the state’s renewable integration targets while avoiding much of the tremendous capital investment of stationary storage that can instead be applied towards further deployment of clean vehicles.

Natural wind variability triggered drop in German redispatch volume and costs from 2015 to 2016.

PubMed

Wohland, Jan; Reyers, Mark; Märker, Carolin; Witthaut, Dirk

2018-01-01

Avoiding dangerous climate change necessitates the decarbonization of electricity systems within the next few decades. In Germany, this decarbonization is based on an increased exploitation of variable renewable electricity sources such as wind and solar power. While system security has remained constantly high, the integration of renewables causes additional costs. In 2015, the costs of grid management saw an all time high of about € 1 billion. Despite the addition of renewable capacity, these costs dropped substantially in 2016. We thus investigate the effect of natural climate variability on grid management costs in this study. We show that the decline is triggered by natural wind variability focusing on redispatch as a main cost driver. In particular, we find that 2016 was a weak year in terms of wind generation averages and the occurrence of westerly circulation weather types. Moreover, we show that a simple model based on the wind generation time series is skillful in detecting redispatch events on timescales of weeks and beyond. As a consequence, alterations in annual redispatch costs in the order of hundreds of millions of euros need to be understood and communicated as a normal feature of the current system due to natural wind variability.

Syntectic Reactions involving Limestones and Limestone-Derived Carbonatitic Melts in the Generation of some Peralkalic Magmas: Reflections on Reginald Daly's Insights 100 Years Later

NASA Astrophysics Data System (ADS)

Lentz, D.

2017-12-01

The theoretical analysis of how sedimentary limestones and marbles could melt as a result of infiltrative contact metasomatism associated with silicate magmas, enables reconsideration of the limestone syntectic (assimilation) hypothesis for the origin of some peralkalic rocks. Reginald Daly's syntectic model published in detail in early 1918 fell out of favor because experimental evidence from the early 1960's suggested; 1) that limestone assimilation would increase P(CO2) and cause solidification of the silicate intrusion, 2) that there is a thermal barrier between silica-saturated and undersaturated magmas that would inhibit extensive desilication of the magma, and 3) the endothermic decarbonation reactions would require heat via magmatic crystallization of near-solidus magmas. However, these concerns were not as critical for high-T mafic melts relative to more low-T silicic melts, although most subsequent researchers dismissed syntexis as isotopic arguments also seemed robust. However, skarn-related limestone melts can interact much more easily with silicate magma, resulting in calc-silicate-forming (endoskarn-like) limestone syntectic (desilication - calcification-magnesification processes) decarbonation reactions with compositional evolution into the silica-undersaturated field. If mafic in composition originally when syntectically modified, then the CO2-bearing derivative peralkalic melt may subsequently react with the dominant volume magma or fractionate separately into a more evolved composition. As well, an increase in P(CO2) within the modified silicate fraction coupled with compositional evolution to more silica-undersaturated compositions enhances the stability of the immiscible, extremely low viscosity carbonate melt fraction. In addition, dynamic interaction of these co-existing immiscible melts (analogous to the current hypothesis) would partition elements, as well as isotopic signatures, such that they would be virtually unrecognizable as having a crustal level syntectic origin, based on mass-balance principles and Rayleigh decarbonation isotopic equilibria, as they do in many infiltrative skarn systems. Essentially, this partly vindicates the basic premise of Daly's limestone syntectic hypothesis for the origin of some peralkalic igneous rocks.

Competing Air Quality and Water Conservation Co-benefits from Power Sector Decarbonization

NASA Astrophysics Data System (ADS)

Peng, W.; Wagner, F.; Mauzerall, D. L.; Ramana, M. V.; Zhai, H.; Small, M.; Zhang, X.; Dalin, C.

2016-12-01

Decarbonizing the power sector can reduce fossil-based generation and associated air pollution and water use. However, power sector configurations that prioritize air quality benefits can be different from those that maximize water conservation benefits. Despite extensive work to optimize the generation mix under an air pollution or water constraint, little research has examined electricity transmission networks and the choice of which fossil fuel units to displace in order to achieve both environmental objectives simultaneously. When air pollution and water stress occur in different regions, the optimal transmission and displacement decisions still depend on priorities placed on air quality and water conservation benefits even if low-carbon generation planning is fixed. Here we use China as a test case, and develop a new optimization framework to study transmission and displacement decisions and the resulting air quality and water use impacts for six power sector decarbonization scenarios in 2030 ( 50% of national generation is low carbon). We fix low-carbon generation in each scenario (e.g. type, location, quantity) and vary technology choices and deployment patterns across scenarios. The objective is to minimize the total physical costs (transmission costs and coal power generation costs) and the estimated environmental costs. Environmental costs are estimated by multiplying effective air pollutant emissions (EMeff, emissions weighted by population density) and effective water use (Weff, water use weighted by a local water stress index) by their unit economic values, Vem and Vw. We are hence able to examine the effect of varying policy priorities by imposing different combinations of Vem and Vw. In all six scenarios, we find that increasing the priority on air quality co-benefits (higher Vem) reduces air pollution impacts (lower EMeff) at the expense of lower water conservation (higher Weff); and vice versa. Such results can largely be explained by differences in optimal transmission decisions due to different locations of air pollution and water stress in China (severe in the east and north respectively). To achieve both co-benefits simultaneously, it is therefore critical to coordinate policies that reduce air pollution (pollution tax) and water use (water pricing) with power sector planning.

Scenarios for Deep Carbon Emission Reductions from Electricity by 2050 in Western North America using the Switch Electric Power Sector Planning Model: California's Carbon Challenge Phase II, Volume II

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

Nelson, James; Mileva, Ana; Johnston, Josiah

2014-01-01

This study used a state-of-the-art planning model called SWITCH for the electric power system to investigate the evolution of the power systems of California and western North America from present-day to 2050 in the context of deep decarbonization of the economy. Researchers concluded that drastic power system carbon emission reductions were feasible by 2050 under a wide range of possible futures. The average cost of power in 2050 would range between $149 to $232 per megawatt hour across scenarios, a 21 to 88 percent increase relative to a business-as-usual scenario, and a 38 to 115 percent increase relative to themore » present-day cost of power. The power system would need to undergo sweeping change to rapidly decarbonize. Between present-day and 2030 the evolution of the Western Electricity Coordinating Council power system was dominated by implementing aggressive energy efficiency measures, installing renewable energy and gas-fired generation facilities and retiring coal-fired generation. Deploying wind, solar and geothermal power in the 2040 timeframe reduced power system emissions by displacing gas-fired generation. This trend continued for wind and solar in the 2050 timeframe but was accompanied by large amounts of new storage and long-distance high-voltage transmission capacity. Electricity storage was used primarily to move solar energy from the daytime into the night to charge electric vehicles and meet demand from electrified heating. Transmission capacity over the California border increased by 40 - 220 percent by 2050, implying that transmission siting, permitting, and regional cooperation will become increasingly important. California remained a net electricity importer in all scenarios investigated. Wind and solar power were key elements in power system decarbonization in 2050 if no new nuclear capacity was built. The amount of installed gas capacity remained relatively constant between present-day and 2050, although carbon capture and sequestration was installed on some gas plants by 2050.« less

Clean energy and the hydrogen economy.

PubMed

Brandon, N P; Kurban, Z

2017-07-28

In recent years, new-found interest in the hydrogen economy from both industry and academia has helped to shed light on its potential. Hydrogen can enable an energy revolution by providing much needed flexibility in renewable energy systems. As a clean energy carrier, hydrogen offers a range of benefits for simultaneously decarbonizing the transport, residential, commercial and industrial sectors. Hydrogen is shown here to have synergies with other low-carbon alternatives, and can enable a more cost-effective transition to de-carbonized and cleaner energy systems. This paper presents the opportunities for the use of hydrogen in key sectors of the economy and identifies the benefits and challenges within the hydrogen supply chain for power-to-gas, power-to-power and gas-to-gas supply pathways. While industry players have already started the market introduction of hydrogen fuel cell systems, including fuel cell electric vehicles and micro-combined heat and power devices, the use of hydrogen at grid scale requires the challenges of clean hydrogen production, bulk storage and distribution to be resolved. Ultimately, greater government support, in partnership with industry and academia, is still needed to realize hydrogen's potential across all economic sectors.This article is part of the themed issue 'The challenges of hydrogen and metals'. © 2017 The Author(s).

The impact of reducing car weight on global emissions: the future fleet in Great Britain

NASA Astrophysics Data System (ADS)

Serrenho, André Cabrera; Norman, Jonathan B.; Allwood, Julian M.

2017-05-01

Current European policies define targets for future direct emissions of new car sales that foster a fast transition to electric drivetrain technologies. However, these targets do not consider the emissions produced in electricity generation and material production, and therefore fail to incentivise car manufacturers to consider the benefits of vehicle weight reduction. In this paper, we examine the potential benefits of limiting the average weight and altering the material composition of new cars in terms of global greenhouse gas emissions produced during the use phase, electricity generation and material production. We anticipate the emissions savings for the future car fleet in Great Britain until 2050 for various alternative futures, using a dynamic material flow analysis of ferrous metals and aluminium, and considering an evolving demand for car use. The results suggest that fostering vehicle weight reduction could produce greater cumulative emissions savings by 2050 than those obtained by incentivising a fast transition to electric drivetrains, unless there is an extreme decarbonization of the electricity grid. Savings promoted by weight reduction are immediate and do not depend on the pace of decarbonization of the electricity grid. Weight reduction may produce the greatest savings when mild steel in the car body is replaced with high-strength steel. This article is part of the themed issue 'Material demand reduction'.

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

Pham Minh, Doan, E-mail: doan.phamminh@mines-albi.fr; Nzihou, Ange; Sharrock, Patrick

Highlights: • Carbonated apatite (CAP) could be easily obtained from CaCO{sub 3} and orthophosphates. • Highest CaCO{sub 3} dissolution and apatitic carbonate content were obtained with H{sub 3}PO{sub 4}. • A-B-type CAP was formed. • The synthesized CAP was thermally stable up to 1000 °C. • This CAP showed high biomineralization activity before and after thermal treatment. - Abstract: The one-step synthesis of carbonated hydroxyapatite (CAP) using calcite and different orthophosphates was investigated in a closed batch reactor. Only orthophosphoric acid could lead to the complete decomposition of calcite particles, when the reaction temperature was set at 80 °C. Onmore » the other hand, the reaction time and the dilution of the initial calcite suspension had no significant influence on the formation of the solid products. CAP was formed as the main crystalline calcium phosphate with the carbonate content in the range of 4.2–4.6 wt.%. The thermal decarbonation of the synthesized CAP started at 750 °C but it was only significant at 1000 °C under air atmosphere. This thermal decarbonation was total at 1200 °C or above. All CAP samples and products following thermal treatments were found bioactive in the test using simulated body fluid (SBF) solution.« less

Natural wind variability triggered drop in German redispatch volume and costs from 2015 to 2016

PubMed Central

Reyers, Mark; Märker, Carolin; Witthaut, Dirk

2018-01-01

Avoiding dangerous climate change necessitates the decarbonization of electricity systems within the next few decades. In Germany, this decarbonization is based on an increased exploitation of variable renewable electricity sources such as wind and solar power. While system security has remained constantly high, the integration of renewables causes additional costs. In 2015, the costs of grid management saw an all time high of about € 1 billion. Despite the addition of renewable capacity, these costs dropped substantially in 2016. We thus investigate the effect of natural climate variability on grid management costs in this study. We show that the decline is triggered by natural wind variability focusing on redispatch as a main cost driver. In particular, we find that 2016 was a weak year in terms of wind generation averages and the occurrence of westerly circulation weather types. Moreover, we show that a simple model based on the wind generation time series is skillful in detecting redispatch events on timescales of weeks and beyond. As a consequence, alterations in annual redispatch costs in the order of hundreds of millions of euros need to be understood and communicated as a normal feature of the current system due to natural wind variability. PMID:29329349

The effect of heated vapor-phase acidification on organic carbon concentrations and isotopic values in geologic rock samples

NASA Astrophysics Data System (ADS)

Wang, R. Z.; West, A. J.; Yager, J. A.; Rollins, N.; Li, G.; Berelson, W.

2016-12-01

Carbon signatures recorded in the modern and geologic rock record can give insight on the Earth's carbon cycle through time. This is especially true for organic carbon (OC), which can help us understand how the biosphere has evolved over Earth's history. However, carbon recorded in rocks is a combination of OC and inorganic carbon (IC) mostly in the form of carbonate minerals. To measure OC, IC must therefore first be removed through a process called "decarbonation." This is often done through a leaching process with hydrochloric acid (HCl). However, three well known problems exist for the decarbonation process: 1) Incomplete removal of IC, 2) Unintentional removal of OC, and 3) Addition of false carbon blank. Currently, vapor (gas) phase removal of OC is preferred to liquid phase treatment because it has been shown that OC is lost to solubilization during liquid phase acidification. Vapor phase treatment is largely thought to avoid the problem of OC loss, but this has not yet been rigorously investigated. This study investigates that assumption and shows that vapor phase treatment can cause unintentional OC loss. We show that vapor phase treatment must be sensitive to rock type and treatment length to produce robust OC isotopic measurements and concentrations.

A retrospective analysis of funding and focus in US advanced fission innovation

NASA Astrophysics Data System (ADS)

Abdulla, A.; Ford, M. J.; Morgan, M. G.; Victor, D. G.

2017-08-01

Deep decarbonization of the global energy system will require large investments in energy innovation and the deployment of new technologies. While many studies have focused on the expenditure that will be needed, here we focus on how government has spent public sector resources on innovation for a key carbon-free technology: advanced nuclear. We focus on nuclear power because it has been contributing almost 20% of total US electric generation, and because the US program in this area has historically been the world’s leading effort. Using extensive data acquired through the Freedom of Information Act, we reconstruct the budget history of the Department of Energy’s program to develop advanced, non-light water nuclear reactors. Our analysis shows that—despite spending 2 billion since the late 1990s—no advanced design is ready for deployment. Even if the program had been well designed, it still would have been insufficient to demonstrate even one non-light water technology. It has violated much of the wisdom about the effective execution of innovative programs: annual funding varies fourfold, priorities are ephemeral, incumbent technologies and fuels are prized over innovation, and infrastructure spending consumes half the budget. Absent substantial changes, the possibility of US-designed advanced reactors playing a role in decarbonization by mid-century is low.

Potential for Electrified Vehicles to Contribute to U.S. Petroleum and Climate Goals and Implications for Advanced Biofuels.

PubMed

Meier, Paul J; Cronin, Keith R; Frost, Ethan A; Runge, Troy M; Dale, Bruce E; Reinemann, Douglas J; Detlor, Jennifer

2015-07-21

To examine the national fuel and emissions impacts from increasingly electrified light-duty transportation, we reconstructed the vehicle technology portfolios from two national vehicle studies. Using these vehicle portfolios, we normalized assumptions and examined sensitivity around the rates of electrified vehicle penetration, travel demand growth, and electricity decarbonization. We further examined the impact of substituting low-carbon advanced cellulosic biofuels in place of petroleum. Twenty-seven scenarios were benchmarked against a 50% petroleum-reduction target and an 80% GHG-reduction target. We found that with high rates of electrification (40% of miles traveled) the petroleum-reduction benchmark could be satisfied, even with high travel demand growth. The same highly electrified scenarios, however, could not satisfy 80% GHG-reduction targets, even assuming 80% decarbonized electricity and no growth in travel demand. Regardless of precise consumer vehicle preferences, emissions are a function of the total reliance on electricity versus liquid fuels and the corresponding greenhouse gas intensities of both. We found that at a relatively high rate of electrification (40% of miles and 26% by fuel), an 80% GHG reduction could only be achieved with significant quantities of low-carbon liquid fuel in cases with low or moderate travel demand growth.

Water conservation implications for decarbonizing non-electric energy supply: A hybrid life-cycle analysis.

PubMed

Liu, Shiyuan; Wang, Can; Shi, Lei; Cai, Wenjia; Zhang, Lixiao

2018-08-01

Low-carbon transition in the non-electric energy sector, which includes transport and heating energy, is necessary for achieving the 2 °C target. Meanwhile, as non-electric energy accounts for over 60% of total water consumption in the energy supply sector, it is vital to understand future water trends in the context of decarbonization. However, few studies have focused on life-cycle water impacts for non-electric energy; besides, applying conventional LCA methodology to assess non-electric energy has limitations. In this paper, a Multi-Regional Hybrid Life-Cycle Assessment (MRHLCA) model is built to assess total CO 2 emissions and water consumption of 6 non-electric energy technologies - transport energy from biofuel and gasoline, heat supply from natural gas, biogas, coal, and residual biomass, within 7 major emitting economies. We find that a shift to natural gas and residual biomass heating can help economies reduce 14-65% CO 2 and save more than 21% water. However, developed and developing economies should take differentiated technical strategies. Then we apply scenarios from IMAGE model to demonstrate that if economies take cost-effective 2 °C pathways, the water conservation synergy for the whole energy supply sector, including electricity, can also be achieved. Copyright © 2018 Elsevier Ltd. All rights reserved.

High-surface-area, dual-function oxygen electrocatalysts for space power applications

NASA Technical Reports Server (NTRS)

Ham, David O.; Moniz, Gary; Taylor, E. Jennings

1987-01-01

The processes of hydration/dehydration and carbonation/decarbonation are investigated as an approach to provide higher surface area mixed metal oxides that are more active electrochemically. These materials are candidates for use as electrocatalysts and electrocatalyst supports for alkaline electrolyzers and fuel cells. For the case of the perovskite, LaCoO3 , higher surface areas were achieved with no change in structure and a more active oxygen electrocatalyst.

Feasibility and Costs of Natural Gas as a Bridge to Deep Decarbonization in the United States

NASA Astrophysics Data System (ADS)

Jones, A. D.; McJeon, H. C.; Muratori, M.; Shi, W.

2015-12-01

Achieving emissions reductions consistent with a 2 degree Celsius global warming target requires nearly complete replacement of traditional fossil fuel combustion with near-zero carbon energy technologies in the United States by 2050. There are multiple technological change pathways consistent with this deep decarbonization, including strategies that rely on renewable energy, nuclear, and carbon capture and storage (CCS) technologies. The replacement of coal-fired power plants with natural gas-fired power plants has also been suggested as a bridge strategy to achieve near-term emissions reduction targets. These gas plants, however, would need to be replaced by near-zero energy technologies or retrofitted with CCS by 2050 in order to achieve longer-term targets. Here we examine the costs and feasibility of a natural gas bridge strategy. Using the Global Change Assessment (GCAM) model, we develop multiple scenarios that each meet the recent US Intended Nationally Determined Contribution (INDC) to reduce GHG emissions by 26%-28% below its 2005 levels in 2025, as well as a deep decarbonization target of 80% emissions reductions below 1990 levels by 2050. We find that the gas bridge strategy requires that gas plants be retired on average 20 years earlier than their designed lifetime of 45 years, a potentially challenging outcome to achieve from a policy perspective. Using a more idealized model, we examine the net energy system costs of this gas bridge strategy compared to one in which near-zero energy technologies are deployed in the near tem. We explore the sensitivity of these cost results to four factors: the discount rate applied to future costs, the length (or start year) of the gas bridge, the relative capital cost of natural gas vs. near-zero energy technology, and the fuel price of natural gas. The discount rate and cost factors are found to be more important than the length of the bridge. However, we find an important interaction as well. At low discount rates, the gas bridge is more expensive and a shorter bridge is preferred. At high discount rates, the gas bridge is less expensive and a longer bridge is preferred. This result indicates that the valuation of future expenditures relative to present day expenditures is a major factor in determining the merits of a gas bridge strategy.

H2 at Scale: Benefitting our Future Energy System - Update for the Hydrogen Technical Advisory Committee

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

Ruth, Mark

2016-12-06

Hydrogen is a flexible, clean energy carrying intermediate that enables aggressive market penetration of renewables while deeply decarbonizing our energy system. H2 at Scale is a concept that supports the electricity grid by utilizing energy without other demands at any given time and also supports transportation and industry by providing low-priced hydrogen to them. This presentation is an update to the Hydrogen Technical Advisory Committee (HTAC).

The impact of reducing car weight on global emissions: the future fleet in Great Britain

PubMed Central

Norman, Jonathan B.; Allwood, Julian M.

2017-01-01

Current European policies define targets for future direct emissions of new car sales that foster a fast transition to electric drivetrain technologies. However, these targets do not consider the emissions produced in electricity generation and material production, and therefore fail to incentivise car manufacturers to consider the benefits of vehicle weight reduction. In this paper, we examine the potential benefits of limiting the average weight and altering the material composition of new cars in terms of global greenhouse gas emissions produced during the use phase, electricity generation and material production. We anticipate the emissions savings for the future car fleet in Great Britain until 2050 for various alternative futures, using a dynamic material flow analysis of ferrous metals and aluminium, and considering an evolving demand for car use. The results suggest that fostering vehicle weight reduction could produce greater cumulative emissions savings by 2050 than those obtained by incentivising a fast transition to electric drivetrains, unless there is an extreme decarbonization of the electricity grid. Savings promoted by weight reduction are immediate and do not depend on the pace of decarbonization of the electricity grid. Weight reduction may produce the greatest savings when mild steel in the car body is replaced with high-strength steel. This article is part of the themed issue ‘Material demand reduction’. PMID:28461428

The impact of reducing car weight on global emissions: the future fleet in Great Britain.

PubMed

Serrenho, André Cabrera; Norman, Jonathan B; Allwood, Julian M

2017-06-13

Current European policies define targets for future direct emissions of new car sales that foster a fast transition to electric drivetrain technologies. However, these targets do not consider the emissions produced in electricity generation and material production, and therefore fail to incentivise car manufacturers to consider the benefits of vehicle weight reduction. In this paper, we examine the potential benefits of limiting the average weight and altering the material composition of new cars in terms of global greenhouse gas emissions produced during the use phase, electricity generation and material production. We anticipate the emissions savings for the future car fleet in Great Britain until 2050 for various alternative futures, using a dynamic material flow analysis of ferrous metals and aluminium, and considering an evolving demand for car use. The results suggest that fostering vehicle weight reduction could produce greater cumulative emissions savings by 2050 than those obtained by incentivising a fast transition to electric drivetrains, unless there is an extreme decarbonization of the electricity grid. Savings promoted by weight reduction are immediate and do not depend on the pace of decarbonization of the electricity grid. Weight reduction may produce the greatest savings when mild steel in the car body is replaced with high-strength steel.This article is part of the themed issue 'Material demand reduction'. © 2017 The Authors.

How Well Do We Know the Future of CO2 Emissions? Projecting Fleet Emissions from Light Duty Vehicle Technology Drivers.

PubMed

Martin, Niall P D; Bishop, Justin D K; Boies, Adam M

2017-03-07

While the UK has committed to reduce CO 2 emissions to 80% of 1990 levels by 2050, transport accounts for nearly a fourth of all emissions and the degree to which decarbonization can occur is highly uncertain. We present a new methodology using vehicle and powertrain parameters within a Bayesian framework to determine the impact of engineering vehicle improvements on fuel consumption and CO 2 emissions. Our results show how design changes in vehicle parameters (e.g., mass, engine size, and compression ratio) result in fuel consumption improvements from a fleet-wide mean of 5.6 L/100 km in 2014 to 3.0 L/100 km by 2030. The change in vehicle efficiency coupled with increases in vehicle numbers and fleet-wide activity result in a total fleet-wide reduction of 41 ± 10% in 2030, relative to 2012. Concerted internal combustion engine improvements result in a 48 ± 10% reduction of CO 2 emissions, while efforts to increase the number of diesel vehicles within the fleet had little additional effect. Increasing plug-in and all-electric vehicles reduced CO 2 emissions by less (42 ± 10% reduction) than concerted internal combustion engines improvements. However, if the grid decarbonizes, electric vehicles reduce emissions by 45 ± 9% with further reduction potential to 2050.

Carbonation by fluid-rock interactions at high-pressure conditions: Implications for carbon cycling in subduction zones

NASA Astrophysics Data System (ADS)

Piccoli, Francesca; Vitale Brovarone, Alberto; Beyssac, Olivier; Martinez, Isabelle; Ague, Jay J.; Chaduteau, Carine

2016-07-01

Carbonate-bearing lithologies are the main carbon carrier into subduction zones. Their evolution during metamorphism largely controls the fate of carbon, regulating its fluxes between shallow and deep reservoirs. Recent estimates predict that almost all subducted carbon is transferred into the crust and lithospheric mantle during subduction metamorphism via decarbonation and dissolution reactions at high-pressure conditions. Here we report the occurrence of eclogite-facies marbles associated with metasomatic systems in Alpine Corsica (France). The occurrence of these marbles along major fluid-conduits as well as textural, geochemical and isotopic data indicating fluid-mineral reactions are compelling evidence for the precipitation of these carbonate-rich assemblages from carbonic fluids during metamorphism. The discovery of metasomatic marbles brings new insights into the fate of carbonic fluids formed in subducting slabs. We infer that rock carbonation can occur at high-pressure conditions by either vein-injection or chemical replacement mechanisms. This indicates that carbonic fluids produced by decarbonation reactions and carbonate dissolution may not be directly transferred to the mantle wedge, but can interact with slab and mantle-forming rocks. Rock-carbonation by fluid-rock interactions may have an important impact on the residence time of carbon and oxygen in subduction zones and lithospheric mantle reservoirs as well as carbonate isotopic signatures in subduction zones. Furthermore, carbonation may modulate the emission of CO2 at volcanic arcs over geological time scales.

Providing sustainable catalytic solutions for a rapidly changing world: a summary and recommendations for urgent future action.

PubMed

Thomas, John Meurig

2018-01-13

In addition to summarizing the main thrusts of each paper presented at this Discussion, other urgent issues involving the role (and characterization) of new catalysts for eliminating oxides of nitrogen, for using CO 2 liberated from steel mills, for fuel cells and the need for rapid decarbonization of fossil fuels are outlined.This article is part of a discussion meeting issue 'Providing sustainable catalytic solutions for a rapidly changing world'. © 2017 The Author(s).

[The use of micromycetes for cleaning parts of aircraft].

PubMed

Dotsenko, G N; Feofilova, E P; Tereshina, V M; Memorskaia, A S

2001-01-01

The mycelial Fungi Penicillium funiculosum, P. citrinum, P. expansum, P. chrysogenum, Aspergillus ochraceus, A. alliaceus, A. luchaensis, A. flavus, and A. niger were isolated from enrichment cultures. These fungi actively destruct carbon deposits formed during exploitation of aircraft. A biotechnological method for removing fouling from parts of aircraft engines (PAE) was developed. This method is less laborious, more rapid and ecologically clean than contemporary chemical methods. Scanning microscopy was suggested to use for estimating the degree of decarbonization of PAE surfaces.

Quantification of fossil organic matter in contaminated sediments from an industrial watershed: validation of the quantitative multimolecular approach by radiocarbon analysis.

PubMed

Jeanneau, Laurent; Faure, Pierre

2010-09-01

The quantitative multimolecular approach (QMA) based on an exhaustive identification and quantification of molecules from the extractable organic matter (EOM) has been recently developed in order to investigate organic contamination in sediments by a more complete method than the restrictive quantification of target contaminants. Such an approach allows (i) the comparison between natural and anthropogenic inputs, (ii) between modern and fossil organic matter and (iii) the differentiation between several anthropogenic sources. However QMA is based on the quantification of molecules recovered by organic solvent and then analyzed by gas chromatography-mass spectrometry, which represent a small fraction of sedimentary organic matter (SOM). In order to extend the conclusions of QMA to SOM, radiocarbon analyses have been performed on organic extracts and decarbonated sediments. This analysis allows (i) the differentiation between modern biomass (contemporary (14)C) and fossil organic matter ((14)C-free) and (ii) the calculation of the modern carbon percentage (PMC). At the confluence between Fensch and Moselle Rivers, a catchment highly contaminated by both industrial activities and urbanization, PMC values in decarbonated sediments are well correlated with the percentage of natural molecular markers determined by QMA. It highlights that, for this type of contamination by fossil organic matter inputs, the conclusions of QMA can be scaled up to SOM. QMA is an efficient environmental diagnostic tool that leads to a more realistic quantification of fossil organic matter in sediments. Copyright 2010 Elsevier B.V. All rights reserved.

Change in the Nd isotopic composition of the bottom water and detrital sediments on the Bering Slope over the last 500 kyrs with implications for the formation of the North Pacific Intermediate Water

NASA Astrophysics Data System (ADS)

Jang, K.; Huh, Y.; Han, Y.

2015-12-01

The Bering Sea is a potential location for the formation of the North Pacific Intermediate/Deep Water (NPIW/NPDW) and may play an important role in the global heat distribution. We reconstructed the neodymium isotopic ratio (ɛNd) of authigenic Fe-Mn oxide coatings and detrital sediments on the Bering Slope (IODP Expedition 323 site U1345; water depth 1008 m) over the last 500 kyrs. The ɛNd is a quasi-conservative water mass tracer. We compared three different leaching techniques to assure that authigenic signals are captured without contamination from terrigenous sources: (1) leaching (3 hours) with 0.02 M hydroxylamine hydrochloride (HH) in 25% buffered acetic acid after decarbonation; sediment/solution (v/v) > 10, (2) leaching (1 hour) with 0.02 M HH in 25% buffered acetic acid without decarbonation; sediment/solution ~ 1, and (3) leaching (1 hour) with 0.005 M HH in 1.5% buffered acetic acid-0.003 M Na-EDTA without decarbonation; sediment/solution > 40. The low Al concentrations and less radiogenic ɛNdvalues indicated that method (2) is the most appropriate leaching process. The average ɛNd of the authigenic fraction over the last 500 kyrs is -3.3 ± 0.9 (1σ, n=38), with large temporal fluctuations. The ɛNd of authigenic and detrital fractions are well correlated (r2 ~ 0.66), suggesting that the bottom water composition in the Bering Sea was governed by terrigenous inflow from surrounding areas. Radiogenic ɛNd peaks (up to -1.9) seem to be influenced by radiogenic water inflow from the the Kamchatka or Aluetian arcs. The high bulk density and low b* values imply higher terrigenous versus biological contribution and enhanced sea ice formation. Subsequent brine formation would have triggered sinking of radiogenic surface water, forming the NPIW. On the other hand, non-radiogenic ɛNd troughs (down to -5.3) are observed at times of low bulk density and high b* values. We presume higher biological productivity which is supported by the high opal content at these intervals (Kanematsu et al., 2013). Sea level rise and boundary exchange with terrigenous sediment derived from N. America is a likely mechanism. This work was supported by the Basic Science Research Program through the NRF funded by Ministry of Science, ICT and Future Planning (No. 2014 0498836)

Carbon Legacy of Forest Degradation Foregone: can Europe's Forests Contribute to Deep Decarbonization?

NASA Astrophysics Data System (ADS)

Kauppi, P.; Nabuurs, G. J.

2016-12-01

Contemporary European forests, comprising 161 Mha, play a large role in mitigation of the EU carbon emissions. These intensively managed forests, roughly compensate 10% of EU emissions in forest carbon, in synchrony with the harvest for lumber, fibre and bioenergy, . But this has not always been the case; European forests are recovering since roughly 1850 from thousands of years of human induced degradation. The impact of more recent management is profound and has stimulated a worldwide unique and unprecedented recovery of this forest biome, partly in terms of area, but mainly in forest density that is, biomass per hectare increases. Based on what we know of the recent historic development, can these forests further contribute to deep decarbonization and how? We outline historic development of European forests since roughly 0 AD. We sketch evidence on degradation and deforestation, and on the impact of forest management on restoring the forest growth thus feeding on biomass recovery. We estimate the historical trajectory of the recovery from forest degradation. We discuss the future pathways of European forest resources, and the prospects for the European-model recovery to occur in degraded forests of the other continents. Based on this evidence from the past, we outline what Climate Smart Forestry could mean in the European circumstances aiming to further strengthen this role of European forests. Big scientific challenges remain to understand and project the future development of these forests under climate change and natural disturbances closely entangled with forest management and new demands of industry in the bio-economy.

Clean Restructuring: Design Elements for Low Carbon Wholesale Markets and Beyond

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

None, None

Countries around the world are in various stages of power system reform and restructuring to more effectively meet development goals and decarbonization commitments. Changes in social dynamics, technology, business models, and environmental goals are increasing pressure for countries to consider improvements to their power systems. This brochure overviews the 21st Century Power Partnerships thought leadership report that explores the clean restructuring pathway in depth, envisions an end state, and articulates three main areas of consideration for decision makers embarking on a clean restructuring process. The report also details case studies from Germany, Denmark, and Mexico.

Mössbauer study on the deformed surface of high-manganese steel

NASA Astrophysics Data System (ADS)

Nasu, S.; Tanimoto, H.; Fujita, F. E.

1990-07-01

Conversion electron, X-ray backscattering and conventional transmission57Fe Mössbauer measurements have been performed to investigate the origin of the remarkable work hardening at the surface of a high-manganese steel which is called Hadfield steel. Mössbauer results show that α' martensite has no relation to work hardening. From the comparison of conversion electron to X-ray backscattering spectra, the occurrence of decarbonization is suggested at the surface. The transmission Mössbauer spectrum at 20 K for deformed specimen shows the existence of ɛ martensite which could be related to the work hardening of Hadfield steel.

Fiber-Reinforced Rocks Akin to Roman Concrete Help Explain Ground Deformation at Campi Flegrei Caldera

NASA Astrophysics Data System (ADS)

Vanorio, Tiziana; Kanitpanyacharoen, Waruntorn

2016-04-01

The caldera of Campi Flegrei is one of the active hydrothermal systems of the Mediterranean region experiencing notable unrest episodes in a densely populated area. During the last crisis of 1982-1984, nearly 40,000 people were evacuated for almost two years from the main town of Pozzuoli, the Roman Puteoli, due to the large uplifts (~2 m over two years) and the persistent seismic activity. The evacuation severely hampered the economy and the social make-up of the community, which included the relocation of schools and commercial shops as well as the harbor being rendered useless for docking. Despite the large uplifts, the release of strain appears delayed. Seismicity begins and reaches a magnitude of 4.0 only upon relatively large uplifts (~ 70-80 cm) contrary to what is generally observed for calderas exhibiting much lower deformation levels. Over and above the specific mechanism causing the unrest and the lack of identification of a shallow magmatic reservoir (< 4 km) by seismic data, there is a core question of how the subsurface rocks of Campi Flegrei withstand a large strain and have high strength. We performed a series of direct measurements on deep well cores by combining high-resolution microstructural and mineralogical analyses with the elastic and mechanical properties of well cores from the deep wells drilled in the area right before the unrest of 1982-1984 - San Vito (SV1 and SV2) and Mofete (MF1, MF2, MF5). The rock physics analysis of the well cores provides evidence for the existence of two horizons, above and below the seismogenic area, underlying a natural, coupled process. The basement is a calc-silicate rock housing hydrothermal decarbonation reactions, which provide lime-rich fluids. The caprock above the seismogenic area has a pozzolanic composition and a fibril-rich matrix made of intertwining filaments of ettringite and tobemorite, resulting from lime-pozzolanic reactions. These findings provide evidence for a natural process reflecting that engineering the mortar of the Roman concrete. The formation of fibrous minerals by intertwining filaments confers shear and tensile strength to the caprock, contributing to its ductility and increased resistance to fracture. The importance of the findings reported in this study lies not only on the fibrous and compositionally nature of the caprock but also on its possible physicochemical deterioration. Given the P-T-XCO2 conditions regulating the decarbonation reactions, the influx of new fluids into the Campi Flegrei system lowers the temperature of the decarbonation reaction and dilutes the existing CO2, thus triggering additional CO2, methane, and steam to form. As these gases rise toward the surface, the natural cement layer halts them, leading to pore pressure increase and subsequent ground deformations.

Multi-scale investigation into the mechanisms of fault mirror formation in seismically active carbonate rocks

NASA Astrophysics Data System (ADS)

Ohl, Markus; Chatzaras, Vasileios; Niemeijer, Andre; King, Helen; Drury, Martyn; Plümper, Oliver

2017-04-01

Mirror surfaces along principal slip zones in carbonate rocks have recently received considerable attention as they are thought to form during fault slip at seismic velocities and thus may be a marker for paleo-seismicity (Siman-Tov et al., 2013). Therefore, these structures represent an opportunity to improve our understanding of earthquake mechanics in carbonate faults. Recent investigations reported the formation of fault mirrors in natural rocks as well as in laboratory experiments and connected their occurrence to the development of nano-sized granular material (Spagnuolo et al., 2015). However, the underlying formation and deformation mechanisms of these fault mirrors are still poorly constrained and warrant further research. In order to understand the influence and significance of these fault products on the overall fault behavior, we analysed the micro-, and nanostructural inventory of natural fault samples containing mirror slip surfaces. Here we present first results on the possible formation mechanisms of fault mirrors and associated deformation mechanisms operating in the carbonate fault gouge from two seismically active fault zones in central Greece. Our study specifically focuses on mirror slip surfaces obtained from the Arkitsa fault in the Gulf of Evia and the Schinos fault in the Gulf of Corinth. The Schinos fault was reactivated by a magnitude 6.7 earthquake in 1981 while the Arkitsa fault is thought to have been reactivated by a magnitude 6.9 earthquake in 1894. Our investigations encompass a combination of state-of-the-art analytical techniques including X-ray computed tomography, focused ion beam scanning electron microscopy (FIB-SEM), transmission electron microscopy (TEM) and Raman spectroscopy. Using this multiscale analytical approach, we report decarbonation-reaction structures, considerable calcite twinning and grain welding immediately below the mirror slip surface. Grains or areas indicating decarbonation reactions show a foam-like, grainy texture. Some areas show a lamellar structure of decarbonated and intact calcite, representing former calcite twins. The average grain size of welded grains is between 100 - 200 nm. In addition, we identified the formation of an amorphous calcium-bearing phase that is enriched in Al, Fe, Si and Mg compared to the host calcite. This phase covers the coarser calcite grains as a thin film and welds them together as well as infiltrating cleavage planes, cracks and surface corrugations on top of the principal mirror slip surface. Thus, it contributes to creating a highly smooth slip surface. References: Siman-Tov et al., 2013, Nanograins form carbonate fault mirrors: Geology, v. 41; no. 6; p. 703-706. Spagnuolo et al., 2015, Fast-moving dislocations trigger flash weakening in carbonate bearing faults during earthquakes: Nature Scientific Reports 5:1611

Geochemistry of primary-carbonate bearing K-rich igneous rocks in the Awulale Mountains, western Tianshan: Implications for carbon-recycling in subduction zone

NASA Astrophysics Data System (ADS)

Yang, Wu-Bin; Niu, He-Cai; Shan, Qiang; Chen, Hua-Yong; Hollings, Pete; Li, Ning-Bo; Yan, Shuang; Zartman, Robert E.

2014-10-01

Arc magmatism plays an important role in the recycling of subducted carbon and returning it to the surface. However, the transfer mechanisms of carbon are poorly understood. In this study, the contribution of subducted carbonate-rich sediments to the genesis of the carbonate-bearing K-rich igneous rocks from western Tianshan was investigated. Four key triggers are involved, including sediments subduction, slab decarbonation, partial melting and magma segregation. The globular carbonate ocelli show C-O isotope signatures intermediate between oceanic sediments and mantle, suggesting that the carbon of the primary carbonate ocelli was derived from recycled subducted sediments in the mantle. Decarbonation of the subducted slab is regarded as the primary agent to carbonize the mantle wedge. Geochemical features indicate that the carbonate ocelli are primary, and that the parental K- and carbon-rich mafic alkaline magma was derived from partial melting of carbonated mantle wedge veined with phlogopite. Major and trace element compositions indicate that globular carbonate ocelli hosted in the Bugula K-rich igneous rocks are calcio-carbonate and formed primarily by segregation of the differentiated CO2-rich alkaline magma after crystallization fractionation. The K-rich alkaline magma, which formed from partial melting of metasomatized (i.e., phlogopite bearing) mantle wedge in the sub-arc region, is a favorable agent to transport subducted carbon back to the Earth's surface during carbon recycling in subduction zones, because of the high CO2 solubility in alkaline mafic magma. We therefore propose a model for the petrogenesis of the carbonate-bearing K-rich igneous rocks in western Tianshan, which are significant for revealing the mechanism of carbon recycling in subduction zones.

The Role of Technology for Achieving Climate Policy Objectives: Overview of the EMF 27 Study on Technology Strategies and Climate Policy Scenarios

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

Kriegler, Elmar; Weyant, John; Blanford, Geoffrey J.

2014-04-01

This article presents the synthesis of results from the Stanford Energy Modeling Forum Study 27, an inter-comparison of 19 energy-economy and integrated assessment models. The study investigated the value of individual mitigation technologies such as energy intensity improvements, carbon capture and sequestration (CCS), nuclear power, solar and wind power and bioenergy for climate mitigation. Achieving atmospheric greenhouse gas concentration targets at 450 and 550 ppm CO2 equivalent requires massive greenhouse gas emissions reductions. A fragmented policy approach at the level of current ambition is inconsistent with these targets. The availability of a negative emissions technology, in most models biofuels withmore » CCS, proved to be a key element for achieving the climate targets. Robust characteristics of the transformation of the energy system are increased energy intensity improvements and the electrification of energy end use coupled with a fast decarbonization of the electricity sector. Non-electric energy end use is hardest to decarbonize, particularly in the transport sector. Technology is a key element of climate mitigation. Versatile technologies such as CCS and bioenergy have largest value, due in part to their combined ability to produce negative emissions. The individual value of low-carbon power technologies is more limited due to the many alternatives in the sector. The scale of the energy transformation is larger for the 450 ppm than for the 550 ppm CO2e target. As a result, the achievability and the costs of the 450 ppm target are more sensitive to variations in technology variability. Mitigation costs roughly double when moving from 550 ppm to 450 ppm CO2e, but remain below 3% of GDP for most models.« less

Countdown to Drawdown: an initial overview of exponential scaling of potential societal tipping points for deep decarbonization of global energy infrastructure by 2050

NASA Astrophysics Data System (ADS)

McCaffrey, Mark; Bhowmik, Avit

2017-04-01

The 194 signatories to the Paris Agreement range in size from small island nations (Tuvalu, less than 10,000 people) to massive states (India and China, which between them have 2.6 billion people). Their cultural backgrounds, political, economic and social systems vary widely. What they all share is an agreement for climate stabilisation at 1.5-2˚ C. A roadmap outlining potential exponential transitions towards a carbon-free economy may benefit from a logarithmic "powers of ten" framework that sets aside backgrounds and systems to examine the relative population concentration scales-from the individual (100) to local/neighborhood (103) to the national/transnational scales (108) and ultimately the global population of around 10 billion anticipated in 2050 (1010). What are the related targets and indicators for successful engagement at each level for rapid and radical reductions of carbon emissions and concentrations? What are the possible interventions and barriers that may be applied at different levels of population concentration? What "drawdown" strategies are most appropriate for different scales? Could focusing demonstrations of clean energy and sustainable practices on the local/neighborhood to urban scale (103-104) provide a leverage that has not been achieved at more complex national and transnational scales? Ultimately, backgrounds and systems are important factors in the equation, but the "powers of 10" scaling framework may provide a compass to assist in identifying the challenges, opportunities and related thresholds and tipping points for achieving deep decarbonization and transformation of the global energy infrastructure at every level of society over the next thirty-three years.

Infiltration-driven metamorphism, New England, USA: Regional CO2 fluxes and implications for Devonian climate and extinctions

NASA Astrophysics Data System (ADS)

Stewart, E. M.; Ague, Jay J.

2018-05-01

We undertake thermodynamic pseudosection modeling of metacarbonate rocks in the Wepawaug Schist, Connecticut, USA, and examine the implications for CO2 outgassing from collisional orogenic belts. Two broad types of pseudosections are calculated: (1) a fully closed-system model with no fluid infiltration and (2) a fluid-buffered model including an H2O-CO2 fluid of a fixed composition. This fluid-buffered model is used to approximate a system open to infiltration by a water-bearing fluid. In all cases the fully closed-system model fails to reproduce the observed major mineral zones, mineral compositions, reaction temperatures, and fluid compositions. The fluid-infiltrated models, on the other hand, successfully reproduce these observations when the XCO2 of the fluid is in the range ∼0.05 to ∼0.15. Fluid-infiltrated models predict significant progressive CO2 loss, peaking at ∼50% decarbonation at amphibolite facies. The closed-system models dramatically underestimate the degree of decarbonation, predicting only ∼15% CO2 loss at peak conditions, and, remarkably, <1% CO2 loss below ∼600 °C. We propagate the results of fluid-infiltrated pseudosections to determine an areal CO2 flux for the Wepawaug Schist. This yields ∼1012 mol CO2 km-2 Myr-1, consistent with multiple independent estimates of the metamorphic CO2 flux, and comparable in magnitude to fluxes from mid-ocean ridges and volcanic arcs. Extrapolating to the area of the Acadian orogenic belt, we suggest that metamorphic CO2 degassing is a plausible driver of global warming, sea level rise, and, perhaps, extinction in the mid- to late-Devonian.

Evaluating the efficiency of nuclear energy policies: an empirical examination for 26 countries.

PubMed

Gozgor, Giray; Demir, Ender

2017-08-01

The decarbonization of the global economy is an urgent concern. As a potential solution, it can be important to understand the efficiency of nuclear energy policies. For this purpose, the paper analyzes whether there is a unit root in nuclear energy consumption in 26 countries and it uses the unit root tests with two endogenous (unknown) structural breaks. The paper finds that nuclear energy consumption is stationary around a level and the time trend in 25 of 26 countries and nuclear energy consumption contains a unit root only in France. The paper also discusses the potential implications of the findings.

Clean Restructuring: Design Elements for Low-Carbon Wholesale Markets and Beyond. A 21st Century Power Partnership Thought Leadership Report

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

Shah, Monisha; Valenzuela, Jose Maria; Mora, Hector Alejandro Beltran

Countries around the world are in various stages of reforming and restructuring their power systems to better meet development needs and decarbonization commitments. Changes in technology, business models, societal needs, and environmental goals are increasing pressure on countries to consider improvements to their power systems. This report addresses key issues associated with clean restructuring--the transition from traditional, vertically integrated utilities to competitive wholesale markets that rely increasingly on variable renewable electricity sources, demand response, and other clean energy options. The report also includes case studies from Mexico, Denmark, and Germany to provide real-world examples of clean restructuring from different perspectives.

Historical emissions critical for mapping decarbonization pathways

NASA Astrophysics Data System (ADS)

Majkut, J.; Kopp, R. E.; Sarmiento, J. L.; Oppenheimer, M.

2016-12-01

Policymakers have set a goal of limiting temperature increase from human influence on the climate. This motivates the identification of decarbonization pathways to stabilize atmospheric concentrations of CO2. In this context, the future behavior of CO2 sources and sinks define the CO2 emissions necessary to meet warming thresholds with specified probabilities. We adopt a simple model of the atmosphere-land-ocean carbon balance to reflect uncertainty in how natural CO2 sinks will respond to increasing atmospheric CO2 and temperature. Bayesian inversion is used to estimate the probability distributions of selected parameters of the carbon model. Prior probability distributions are chosen to reflect the behavior of CMIP5 models. We then update these prior distributions by running historical simulations of the global carbon cycle and inverting with observationally-based inventories and fluxes of anthropogenic carbon in the ocean and atmosphere. The result is a best-estimate of historical CO2 sources and sinks and a model of how CO2 sources and sinks will vary in the future under various emissions scenarios, with uncertainty. By linking the carbon model to a simple climate model, we calculate emissions pathways and carbon budgets consistent with meeting specific temperature thresholds and identify key factors that contribute to remaining uncertainty. In particular, we show how the assumed history of CO2 emissions from land use change (LUC) critically impacts estimates of the strength of the land CO2 sink via CO2 fertilization. Different estimates of historical LUC emissions taken from the literature lead to significantly different parameterizations of the carbon system. High historical CO2 emissions from LUC lead to a more robust CO2 fertilization effect, significantly lower future atmospheric CO2 concentrations, and an increased amount of CO2 that can be emitted to satisfy temperature stabilization targets. Thus, in our model, historical LUC emissions have a significant impact on allowable carbon budgets under temperture targets.

Environmental and natural resource implications of sustainable urban infrastructure systems

NASA Astrophysics Data System (ADS)

Bergesen, Joseph D.; Suh, Sangwon; Baynes, Timothy M.; Kaviti Musango, Josephine

2017-12-01

As cities grow, their environmental and natural resource footprints also tend to grow to keep up with the increasing demand on essential urban services such as passenger transportation, commercial space, and thermal comfort. The urban infrastructure systems, or socio-technical systems providing these services are the major conduits through which natural resources are consumed and environmental impacts are generated. This paper aims to gauge the potential reductions in environmental and resources footprints through urban transformation, including the deployment of resource-efficient socio-technical systems and strategic densification. Using hybrid life cycle assessment approach combined with scenarios, we analyzed the greenhouse gas (GHG) emissions, water use, metal consumption and land use of selected socio-technical systems in 84 cities from the present to 2050. The socio-technical systems analyzed are: (1) bus rapid transit with electric buses, (2) green commercial buildings, and (3) district energy. We developed a baseline model for each city considering gross domestic product, population density, and climate conditions. Then, we overlaid three scenarios on top of the baseline model: (1) decarbonization of electricity, (2) aggressive deployment of resource-efficient socio-technical systems, and (3) strategic urban densification scenarios to each city and quantified their potentials in reducing the environmental and resource impacts of cities by 2050. The results show that, under the baseline scenario, the environmental and natural resource footprints of all 84 cities combined would increase 58%-116% by 2050. The resource-efficient scenario along with strategic densification, however, has the potential to curve down GHG emissions to 17% below the 2010 level in 2050. Such transformation can also limit the increase in all resource footprints to less than 23% relative to 2010. This analysis suggests that resource-efficient urban infrastructure and decarbonization of electricity coupled with strategic densification have a potential to mitigate resources and environmental footprints of growing cities.

First in-situ monitoring of CO2 delivery to the mantle followed by compression melting, using synchrotron generated X-ray diffraction.

NASA Astrophysics Data System (ADS)

Hammouda, Tahar; Chantel, Julien; Manthilake, Geeth; Guignard, Jérémy; Crichton, Wilson; Gaillard, Fabrice

2014-05-01

Melting of peridotite + CO2 upon compression has been directly monitored in situ, for the first time. We have combined high pressure experiments in the multianvil apparatus with synchrotron-generated X-ray diffraction, in order to monitor sample decarbonation upon heating, followed by melting upon compression. Experiments were performed in the model system CaO-MgO-SiO2+CO2, using dolomite and silicates contained in graphite capsules as starting material. Save Al, starting composition was aimed at reproducing peridotitic system. The sample was first compressed at room temperature, then heated. Decarbonation was observed at 2.2 GPa and 1100°C. After further heating to 1300°C, pressure was increased. Melting was observed at 2.7 GPa, while temperature was kept at 1300°C. All transformations were followed using X-ray diffraction. Starting with silicate + carbonate mixtures, we were thus able to keep CO2 fluid in the experimental sample at high P and T, up to the solidus. Concerning carbon recycling at subduction zones, it is known that CO2 is a non-wetting fluid in silicate aggregates. Therefore, any CO2 resulting from carbonate breakdown likely remains trapped at grain corners either in the subducted lithosphere or in the mantle wedge before eventually being trapped in mantle minerals as fluid inclusions, due to dynamic recrystallization. In this way, CO2 released from the slab may be spread laterally due to mantle convection. Entrainment to further depths by deep subduction or in convection cells induces CO2 introduction to depth wherein the solidus can be crossed, due to pressure increase. The solidus corresponds to the so-called carbonate ledge, beyond which carbonatitic melts are produced. Therefore, compression melting of CO2-bearing lithologies is a way to produce carbonatitic melts at depths corresponding to about 80 km. This mechanism is a viable explanation for the observed geophysical anomalies, such as those revealed by electrical conductivity measurements.

Framing clean energy campaigns to promote civic engagement among parents

NASA Astrophysics Data System (ADS)

Hanus, Nichole; Wong-Parodi, Gabrielle; Hoyos, Lisa; Rauch, Molly

2018-03-01

Civic engagement is one important way citizens can influence the rate of decarbonization in the electricity sector. However, motivating engagement can be challenging even if people are affected and interested in participating. Here we employed a randomized controlled trial to assess the effect of clean energy campaigns emphasizing cost savings, health, climate, or health and climate, or no additional information at all (control) on civic engagement behaviors (signing a petition or making a phone call). We targeted parents as they have been shown to be powerful agents of political and business practice change in other contexts, and hence, could play an important role in the decarbonization of the electricity sector. In Study 1, we recruited n = 292 parents already engaged in climate advocacy; in Study 2, we recruited a representative sample of n = 1254 parents drawn from the general public. Both studies were conducted in Michigan, Florida, and California, as these states have sizable advocacy group membership, divergent energy profiles, and strategic importance to the climate movement. In both studies, we find the odds of taking action are reduced by over 90% when participants are asked to make a phone call and leave a voicemail message, versus signing an online petition. Among the parents already engaged in advocacy, we observe a ceiling effect regarding attitudes towards clean energy and find the cost campaign produces unintended consequences. Among our public sample, we find that participants who believe the campaign to be credible and comprehendible are more likely to take action than those who discredit the campaign or do not understand its message. Additionally, we find parents who have children under the age of 18 negatively adjust their attitudes towards fossil fuels after being presented with health information. Ultimately, we find that campaign messages can influence energy attitudes and parents are willing to take action on the topic if the advocacy action seems like an effective approach.

Evaluating the Extent of C Cycling Through a Cold Subduction Zone: New Clues from Izu- Bonin Melt Inclusions

NASA Astrophysics Data System (ADS)

Shaw, A. M.; Hauri, E. H.; Fischer, T. P.; Hilton, D. R.

2006-05-01

Subduction zones provide our best window into C cycling processes between Earth's surface reservoirs and the mantle. The efficiency of this process can be constrained through volatile studies of melt inclusions, where measured pre-eruptive CO2 contents are combined with magma production rates to obtain an output CO2 flux. These outputs can then be compared to C inputs from the subducting slab (sedimentary, organic and altered oceanic crust) to evaluate budgets through a given arc system. Decarbonation of the various C components within a slab are strongly controlled by temperature, pressure and fluid availability. The Izu-Bonin subduction zone system is a cold subduction zone and modeled CO2 behaviour for low temperature geotherms suggest that little decarbonation would occur at subarc depths 1. However, fluids can effectively promote decarbonation. Trace element ratios of Izu arc rocks 2 predict that a significant amount of fluid is fluxed through the Izu-Bonin arc system. This study aims to evaluate the extent of C recycling through a cold, yet fluid-rich arc system. Here we report new CO2 melt inclusions abundance data from 4 volcanoes in the Izu-Bonin arc: Nijima, Oshima, Hachijojima and Aogashima. Concentrations of CO2, along with other volatiles (H2O, F, SO2, Cl), were determined using SIMS techniques at the Carnegie Institution of Washington. Various processes can modify intrinsic volatile contents such as degassing, fractional crystallization, crustal contamination and extent of melting, thereby masking true source values. CO2 contents of Izu-Bonin melt inclusions show positive trends with other volatiles (H2O and SO2) and with MgO contents (with the exception of Nijima). This indicates that differentiation and degassing have occurred simultaneously. In this case, we assume that the highest CO2 concentration samples (up to 1200 ppm CO2 from Nijima volcano) best represent pre-eruptive magma compositions. Comparing a total CO2 input of 10.35 Mmol/yr3 to our calculated output of 17.6 Mmol/yr (assuming a magma production rate of 60 km3/km/Myr1) we estimate that approximately 17% of C subducted at the trench is recycled at the arc front. This value is remarkably similar to the C recycling efficiency found at the Central American arc (14-18%)5, where thermal conditions are significantly warmer. 1Kerrick, D.M. and Connolly, J.A.D. Metamorphic devolatization of subducted marine sediments and the transport of volatiles into the Earth's mantle, Nature v. 411, 293-296 (2001). 2Stern, R. J., Fouch, M. J. & Klemperer, S. in Inside the Subduction Factory 175-222 (2003). 3Hilton, D. R., Fischer, T. P. & Marty, B. Rev. in Mineral v. 47 319-370. 4Dimalanta, C., Taira, A., Yumul, G. P., Jr., Tokuyama, H. & Mochizuki, K. EPSL, v. 202, 105-115 (2002). 5Shaw, A. M., Hilton, D. R., Fischer, T. P., Walker, J. A. & Alvarado, G. EPSL v. 214, 499-513 (2003).

Exploring the Potential Business Case for Synergies Between Natural Gas and Renewable Energy

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

Cochran, Jaquelin; Zinaman, Owen; Logan, Jeffrey

2014-02-01

Natural gas and renewable energy each contribute to economic growth, energy independence, and carbon mitigation, sometimes independently and sometimes collectively. Often, natural gas and renewables are considered competitors in markets, such as those for bulk electricity. This paper attempts to address the question, 'Given near- and long-term needs for abundant, cleaner energy sources and decarbonization, how can more compelling business models be created so that these two domestic forms of energy work in greater concert?' This paper explores revenue opportunities that emerge from systems-level perspectives in 'bulk energy' (large-scale electricity and natural gas production, transmission, and trade) and four 'distributionmore » edge' subsectors: industrial, residential, commercial, and transportation end uses.« less

Rapid carbon mineralization for permanent disposal of anthropogenic carbon dioxide emissions

NASA Astrophysics Data System (ADS)

Matter, Juerg M.; Stute, Martin; Snæbjörnsdottir, Sandra Ó.; Oelkers, Eric H.; Gislason, Sigurdur R.; Aradottir, Edda S.; Sigfusson, Bergur; Gunnarsson, Ingvi; Sigurdardottir, Holmfridur; Gunnlaugsson, Einar; Axelsson, Gudni; Alfredsson, Helgi A.; Wolff-Boenisch, Domenik; Mesfin, Kiflom; Taya, Diana Fernandez de la Reguera; Hall, Jennifer; Dideriksen, Knud; Broecker, Wallace S.

2016-06-01

Carbon capture and storage (CCS) provides a solution toward decarbonization of the global economy. The success of this solution depends on the ability to safely and permanently store CO2. This study demonstrates for the first time the permanent disposal of CO2 as environmentally benign carbonate minerals in basaltic rocks. We find that over 95% of the CO2 injected into the CarbFix site in Iceland was mineralized to carbonate minerals in less than 2 years. This result contrasts with the common view that the immobilization of CO2 as carbonate minerals within geologic reservoirs takes several hundreds to thousands of years. Our results, therefore, demonstrate that the safe long-term storage of anthropogenic CO2 emissions through mineralization can be far faster than previously postulated.

The North American Energy System: Overview of the 3rd Chapter of SOCCR-2

NASA Astrophysics Data System (ADS)

Marcotullio, P. J.

2016-12-01

North America, including Canada, Mexico and the United States, has a large and complex energy system, which includes the extraction and conversion of primary energy sources and their storage, transmission, distribution and ultimate end use in the building, transportation and industrial sectors. The chapter overviews this system focusing on our understanding of the energy trends and system feedback dynamics, key drivers of change, and subsequent carbon emissions and the basis for carbon management. We also put the carbon emissions from the North American system in global context. Highlights include the changes to the system (sources, fuel mix, drivers, infrastructure, etc.,) over the past decade, and a review of scenarios that provide glimpses into future emissions levels and meeting the requirements for decarbonization in the medium and longer term.

Switchable hydrophilicity solvents for lipid extraction from microalgae for biofuel production.

PubMed

Boyd, Alaina R; Champagne, Pascale; McGinn, Patrick J; MacDougall, Karen M; Melanson, Jeremy E; Jessop, Philip G

2012-08-01

A switchable hydrophilicity solvent (SHS) was studied for its effectiveness at extracting lipids from freeze-dried samples of Botryococcus braunii microalgae. The SHS N,N-dimethylcyclohexylamine extracted up to 22 wt.% crude lipid relative to the freeze-dried cell weight. The solvent was removed from the extract with water saturated with carbon dioxide at atmospheric pressure and recovered from the water upon de-carbonation of the mixture. Liquid chromatography-mass spectrometry (LC-MS) showed that the extracted lipids contained high concentrations of long chain tri-, di- and mono-acylglycerols, no phospholipids, and only 4-8% of residual solvent. Unlike extractions with conventional organic solvents, this new method requires neither distillation nor the use of volatile, flammable or chlorinated organic solvents. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

Steinberg, Daniel; Bielen, Dave; Eichman, Josh

Electrification of end-use services in the transportation, buildings, and industrial sectors coupled with decarbonization of electricity generation has been identified as one of the key pathways to achieving a low-carbon future in the United States. By lowering the carbon intensity of the electricity generation and substituting electricity for higher-emissions fossil fuels in end-use sectors, significant reductions in carbon dioxide emissions can be achieved. This report describes a preliminary analysis that examines the potential impacts of widespread electrification on the U.S. energy sector. We develop a set of exploratory scenarios under which electrification is aggressively pursued across all end-use sectors andmore » examine the impacts of achieving these electrification levels on electricity load patterns, total fossil energy consumption, carbon dioxide emissions, and the evolution of the U.S. power system.« less

Data on development of new energy technologies

NASA Astrophysics Data System (ADS)

1994-03-01

The paper compiles data on the trend of development of new energy technologies into a book. By category, renewable energy is solar energy, wind power generation, geothermal power generation, ocean energy, and biomass. As a category of fuel form conversion, cited are coal liquefaction/gasification, coal gasification combined cycle power generation, and natural gas liquefaction/decarbonization. The other categories are cogeneration by fuel cell and ceramic gas turbine, district heat supply system, power load leveling technology, transportation-use substitution-fuel vehicle, and others (Stirling engine, superconducting power generator, etc.). The data are systematically compiled on essential principles, transition of introduction, objectives of introduction, status of production, cost, development schedule, performance, etc. The paper also deals with the related legislation system, developmental organizations, and a menu for power companies' buying surplus power.

What Can China Do? China's Best Alternative Outcome for Energy Efficiency and CO2 Emissions

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

G. Fridley, David; Zheng, Nina; T. Aden, Nathaniel

After rapid growth in economic development and energy demand over the last three decades, China has undertaken energy efficiency improvement efforts to reduce its energy intensity under the 11th Five Year Plan (FYP). Since becoming the world's largest annual CO{sub 2} emitter in 2007, China has set reduction targets for energy and carbon intensities and committed to meeting 15% of its total 2020 energy demand with non-fossil fuel. Despite having achieved important savings in 11th FYP efficiency programs, rising per capita income and the continued economic importance of trade will drive demand for transport activity and fuel use. At themore » same time, an increasingly 'electrified' economy will drive rapid power demand growth. Greater analysis is therefore needed to understand the underlying drivers, possible trajectories and mitigation potential in the growing industrial, transport and power sectors. This study uses scenario analysis to understand the likely trajectory of China's energy and carbon emissions to 2030 in light of the current and planned portfolio of programs, policies and technology development and ongoing urbanization and demographic trends. It evaluates the potential impacts of alternative transportation and power sector development using two key scenarios, Continued Improvement Scenario (CIS) and Accelerated Improvement Scenario (AIS). CIS represents the most likely path of growth based on continuation of current policies and meeting announced targets and goals, including meeting planned appliance efficiency standard revisions, fuel economy standards, and industrial targets and moderate phase-out of subcritical coal-fired generation with additional non-fossil generation. AIS represents a more aggressive trajectory of accelerated improvement in energy intensity and decarbonized power and transport sectors. A range of sensitivity analysis and power technology scenarios are tested to evaluate the impact of additional actions such as carbon capture and sequestration (CCS) and integrated mine-mouth generation. The CIS and AIS results are also contextualized and compared to model scenarios in other published studies. The results of this study show that China's energy and CO{sub 2} emissions will not likely peak before 2030, although growth is expected to slow after 2020. Moreover, China will be able to meet its 2020 carbon intensity reduction target of 40 to 45% under both CIS and AIS, but only meet its 15% non-fossil fuel target by 2020 under AIS. Under both scenarios, efficiency remains a key resource and has the same, if not greater, mitigation potential as new technologies in transport and power sectors. In the transport sector, electrification will be closely linked the degree of decarbonization in the power sector and EV deployment has little or no impact on China's crude oil import demand. Rather, power generation improvements have the largest sector potential for overall emission mitigation while mine-mouth power generation and CCS have limited mitigation potential compared to fuel switching and efficiency improvements. Comparisons of this study's results with other published studies reveal that CIS and AIS are within the range of other national energy projections but alternative studies rely much more heavily on CCS for carbon reduction. The McKinsey study, in particular, has more optimistic assumptions for reductions in crude oil imports and coal demand in its abatement scenario and has much higher gasoline reduction potential for the same level of EV deployment. Despite these differences, this study's scenario analysis of both transport and power sectors illustrate the necessity for continued efficiency improvements and aggressive power sector decarbonization in flattening China's CO{sub 2} emissions.« less

Three essays on decision-making in energy policy

NASA Astrophysics Data System (ADS)

Wendling, Zachary Ann

This dissertation examines three issues surrounding decision-making in energy policy. Over the past decade, technological advances in horizontal drilling and hydraulic fracturing have allowed the economical extraction of natural gas and petroleum from shale basins. Thus far, natural gas has been produced from shale at a commercial scale only in certain American States and Canadian Provinces, though potential shale plays exist elsewhere in North America and the world. Whether, how, and to what extent SGD diffuses to new shale basins and jurisdictions will depend on several questions about energy policy. The first chapter examines the potential for SGD in the European Union. Among EU institutions, the European Parliament has been the strongest proponent for regulation of SGD, preferring a balance between environmental protection and opportunities for economic development, energy security, and climate mitigation. Analysis of roll call voting on SGD in the Seventh European Parliament shows that ideological preferences are the primary explanation of voting behavior, followed by national interests in decarbonization. Prospects for further regulatory action are discussed. ? The second chapter takes a closer look at the potential of shale gas to facilitate decarbonization in the electricity sector. Proponents of SGD have claimed that high carbon fossil fuels can be immediately phased out and replaced in the short term by power plants that burn cheap, abundant natural gas, which emits half the greenhouse gasses over a well-to-wire life cycle. A value of information analysis examines the conditions under which this may be so and quantifies how valuable it would be to have perfect information about uncertain parameters in a cost function characterizing the global electricity sector. The third chapter is describes a new tool of policy analysis, the Indiana Scalable Energy-Economy Model (IN-SEEM). State and local governments have played an increasing role in energy and climate policy in the United States and abroad, yet few models can capture the policy impacts at finer geographic scales. Having such tools is essential for local stakeholders as they contemplate energy options such as SGD. This chapter explains the development, performance, and usefulness of IN-SEEM in answering policy questions.

Sulfur degassing due to contact metamorphism during flood basalt eruptions

NASA Astrophysics Data System (ADS)

Yallup, Christine; Edmonds, Marie; Turchyn, Alexandra V.

2013-11-01

We present a study aimed at quantifying the potential for generating sulfur-rich gas emissions from the devolatilization of sediments accompanying sill emplacement during flood basalt eruptions. The potential contribution of sulfur-rich gases from sediments might augment substantially the magma-derived sulfur gases and hence impact regional and global climate. We demonstrate, from a detailed outcrop-scale study, that sulfur and total organic carbon have been devolatilized from shales immediately surrounding a 3-m thick dolerite sill on the Isle of Skye, Scotland. Localized partial melting occurred within a few centimetres of the contact in the shale, generating melt-filled cracks. Pyrite decomposed on heating within 80 cm of the contact, generating sulfur-rich gases (a mixture of H2S and SO2) and pyrrhotite. The pyrrhotite shows 32S enrichment, due to loss of 34S-enriched SO2. Further decomposition and oxidation of pyrrhotite resulted in hematite and/or magnetite within a few cm of the contact. Iron sulfates were produced during retrogressive cooling and oxidation within 20 cm of the contact. Decarbonation of the sediments due to heating is also observed, particularly along the upper contact of the sill, where increasing δ13C is consistent with loss of methane gas. The geochemical and mineralogical features observed in the shales are consistent with a short-lived intrusion, emplaced in <5 h. The dolerite magma contains pervasive pyrite and localized sulfur concentrations greater than the sulfur concentration at sulfide liquid saturation, consistent with addition of sulfur (perhaps from sediments) at a late stage. Our study provides evidence for desulfurization, as well as decarbonation, of shales adjacent to an igneous intrusion. The liberated fluids, rich in sulfur and carbon, are likely to be focused along regions of low pore fluid pressure along the margins of the sill. The sulfur gases liberated from the sediments would have augmented the sulfur dioxide (and hydrogen sulfide) yield of the eruption substantially, had they reached the surface. This enhancement of the magmatic sulfur budget has important implications for the climate impact of large flood basalt eruptions that erupt through thick, volatile-rich sedimentary sequences.

Techno-economic assessment of the need for bulk energy storage in low-carbon electricity systems with a focus on compressed air storage (CAES)

NASA Astrophysics Data System (ADS)

Safaei Mohamadabadi, Hossein

Increasing electrification of the economy while decarbonizing the electricity supply is among the most effective strategies for cutting greenhouse gas (GHG) emissions in order to abate climate change. This thesis offers insights into the role of bulk energy storage (BES) systems to cut GHG emissions from the electricity sector. Wind and solar energies can supply large volumes of low-carbon electricity. Nevertheless, large penetration of these resources poses serious reliability concerns to the grid, mainly because of their intermittency. This thesis evaluates the performance of BES systems - especially compressed air energy storage (CAES) technology - for integration of wind energy from engineering and economic aspects. Analytical thermodynamic analysis of Distributed CAES (D-CAES) and Adiabatic CAES (A-CAES) suggest high roundtrip storage efficiencies ( 80% and 70%) compared to conventional CAES ( 50%). Using hydrogen to fuel CAES plants - instead of natural gas - yields a low overall efficiency ( 35%), despite its negligible GHG emissions. The techno-economic study of D-CAES shows that exporting compression heat to low-temperature loads (e.g. space heating) can enhance both the economic and emissions performance of compressed air storage plants. A case study for Alberta, Canada reveals that the abatement cost of replacing a conventional CAES with D-CAES plant practicing electricity arbitrage can be negative (-$40 per tCO2e, when the heat load is 50 km away from the air storage site). A green-field simulation finds that reducing the capital cost of BES - even drastically below current levels - does not substantially impact the cost of low-carbon electricity. At a 70% reduction in the GHG emissions intensity of the grid, gas turbines remain three times more cost-efficient in managing the wind variability compared to BES (in the best case and with a 15-minute resolution). Wind and solar thus, do not need to wait for availability of cheap BES systems to cost-effectively decarbonize the grid. The prospects of A-CAES seem to be stronger compared to other BES systems due to its low energy-specific capital cost.

Mass transfers induced by flow of CO2 rich-brine through fractured cement: experiment and modeling

NASA Astrophysics Data System (ADS)

Habdoulghafour, H.; Luquot, L.; Gouze, P.

2011-12-01

Long-term confinement failure is a key issue in the assessment of the confidence levels of CO2 storage. Evaluating the potential for CO2 leakage through wells (casing, cements and interfaces with the cap-rock) is of primary importance for the analysis of latent and short-range risks of confinement failure. Some controversy remains regarding the risk of conventional cements. While some researchers argue that they may fail, EOR oil industry experience suggests the opposite. The issue is non-trivial. Experimental investigations on cement alteration mechanism triggered by CO2-rich brine show that both carbonation and de-carbonation mechanisms may occur and are the dominant mass exchange processes. It is tempting to conclude from the results of batch experiments that cement carbonation tends to decrease porosity and permeability, whereas de-carbonation increases both, but these assumptions must be tested using realistic flow-through experiments. Here we investigated the effect of CO2 rich-brine flowing through fractured portlandite-rich cement plugs. Experiments were carried out under realistic in situ conditions (T=80°C and P=10 MPa). Monitoring the fluid composition at the outlet allows us to measure the rate at which portlandite and CSH are dissolved and Ca-carbonate (calcite) precipitated. The precipitation of carbonate limits the fluid access to the inner part of cement (by diffusion) but, in the condition of forced flow-through CO2-rich brine in the fracture, this carbonate layer is subsequently dissolved as showed by the X-ray micro tomography performed post-mortem. Despite these coupled dissolution-precipitation mechanisms (and the on-going reaction front displacement), the permeability of the fracture remains almost constant during the experiment because the effective aperture controlled by the undissolved fraction of the cement (i.e. silica-rich minerals) is preserved. For the studied conditions, it can be concluded that the flow properties of the fractured cements are conserved, while the chemical and probably the mechanical properties of the cement are deeply modified.

Integrating air quality, water and climate concerns into China's energy strategy

NASA Astrophysics Data System (ADS)

Peng, Wei

As the world's top carbon emitter, China also suffers from serious air pollution and increasingly severe water stress. My dissertation focuses on a variety of energy strategies in China and examines potential synergies and tradeoffs between air quality, water conservation and carbon mitigation objectives. It includes four analytical chapters. Chapter 2 and 3 examines the air quality and climate implications of a variety policy options in the near term and at the 2030 time horizon, respectively. Based on an integrated assessment using regional air pollution model and epidemiological evidence, I find that improving industrial energy efficiency is the most effective near-term strategy to curb air pollution and carbon emissions, while electrifying end-use sectors (e.g. vehicles and residential stoves) with decarbonized electricity will likely become the favorable co-control strategy in 2030. These two chapters hence provide a scientific basis for policymakers in China to coordinate air pollution and carbon mitigation strategies. Chapter 4 and 5 then examines the role of electricity transmission, as a critical element of the electrification strategy, in the nexus of air pollution, water stress and carbon emissions. Chapter 4 evaluates the potential air quality and climate benefits of long-distance electricity transmission in China in the near term. I find that transmitting a hybrid mix of renewable and coal power can be a cost-effective energy transfer strategy to curb air pollution impacts and carbon emissions, because it not only utilizes zero-carbon renewable resources in the west, but also displaces coal power generation and associated air pollution impacts in highly populated eastern regions. Chapter 5 studies the potential tradeoffs in the transmission system designs to achieve air quality or water conservation benefits from a decarbonized generation system. Since air pollution and water stress are severe in eastern and northern China respectively, I find that an increasing priority on air pollution control would favor a larger amount of electricity transmission into eastern population centers, while an increasing priority on water conservation would favor using locally produced renewable power or imported electricity to displace fossil generation in northern water-stressed regions.

Electricity diversification, decentralization, and decarbonization: The role of U.S. state energy policy

NASA Astrophysics Data System (ADS)

Carley, Sanya

In response to mounting concerns about climate change and an over-dependence on fossil fuels, U.S. state governments have assumed leadership roles in energy policy. State leaders across the country have constructed policies that target electricity sector operations, and aim to increase the percentage of renewable electricity generation, increase the use of distributed generation, and decrease carbon footprints. The policy literature, however, lacks compelling empirical evidence that state initiatives toward these ends are effective. This research seeks to contribute empirical insights that can help fill this void in the literature, and advance policy knowledge about the efficacy of these instruments. This three-essay dissertation focuses on the assessment of state energy policy instruments aimed at the diversification, decentralization, and decarbonization of the U.S. electricity sector. The first essay considers the effects of state efforts to diversify electricity portfolios via increases in renewable energy. This essay asks: are state-level renewable portfolio standards (RPS) effective at increasing renewable energy deployment, as well as the share of renewable energy out of the total generation mix? Empirical results demonstrate that RPS policies so far are effectively encouraging total renewable energy deployment, but not the percentage of renewable energy generation. The second essay considers state policy efforts to decentralize the U.S. electricity sector via instruments that remove barriers to distributed generation (DG) deployment. The primary question this essay addresses is whether the removal of legal barriers acts as a primary motivating factor for DG deployment. Empirical results reveal that net metering policies are positively associated with DG deployment; interconnection standards significantly increase the likelihood that end-users will adopt DG capacity; and utility DG adoption is related to standard market forces. The third essay asks: what are the potential effects of state energy policy portfolios on carbon emissions within the U.S. electricity sector? The results from an electricity modeling scenario analysis reveal that state policy portfolios have modest to minimal carbon mitigation effects in the long run if surrounding states do not adopt similar portfolios as well. The effectiveness of state-level policy portfolios can increase significantly if surrounding states adopt similar portfolios, or with the introduction of a national carbon price.

The Path Forward from Paris: the Challenge for Tropical Countries

NASA Astrophysics Data System (ADS)

Nobre, C.

2016-12-01

The pledges of emissions reductions put forth at the COP21 in Paris fall short of ensuring the desired guardrail of 2 C warming, let alone the more stringent, but necessary, goal of 1.5 C warming if we want to minimize the increasing risks of climate change over both the short term of decades and the long term of centuries. Decarbonization of the global economy is mandatory, which implies a gargantuan challenge of decarbonizing the energy system. Given the likelihood of decreasing strength of the natural sinks in the global oceans and land biota as warming progresses, it may be necessary to reach nearly zero net emissions by midcentury and even negative net emissions by the end of the century. In addition to massive and rapid implementation of renewable energy systems, desirable mitigation trajectories involve large-scale reforestation and ecosystem restoration and also bioenergy capture and storage systems (BECCS). Tropical countries can play an important role to meet both goals as long as they are able to implement sustainable agriculture at the large scale that is nearly carbon-neutral and resilient to unavoidable climate change. And reaching sustainability in the agricultural sector—remembering that agricultural direct emissions and indirect emissions due to deforestation account for almost one quarter of global emissions—is under the constraint to meet food security for all, that is, food production has to grow 70% by midcentury, with concomitant reduction of waste in the food chain. I will take the example of mitigation options for Brazil—a large tropical country with per capita emissions of about 7.5 ton CO2-eq—to illustrate sustainable development trajectories of reaching carbon neutrality by midcentury. That will imply developing a modern, more productive carbon-neutral agriculture within the next two decades, reducing tropical deforestation to nearly zero within a decade, restoring ecosystems and increasing renewable energy use to over 80% of its total energy consumption by 2050. It will be shown that such ambitious goals are within the realm of reality if some basic conditions are met: a faster cycle of knowledge to policy implementation and technology to practice, and innovative financing mechanisms.

Quantifying the Contribution of Urban-Industrial Efficiency and Symbiosis to Deep Decarbonization: Impact of 637 Chinese Cities

NASA Astrophysics Data System (ADS)

Ramaswami, A.; Tong, K.; Fang, A.; Lal, R.; Nagpure, A.; Li, Y.; Yu, H.; Jiang, D.; Russell, A. G.; Shi, L.; Chertow, M.; Wang, Y.; Wang, S.

2016-12-01

Urban activities in China contribute significantly to global greenhouse gas (GHG) emissions and to local air pollution-related health risks. Co-location analysis can help inform the potential for energy- and material-exchanges across homes, businesses, infrastructure and industries co-located in cities. Such co-location dependent urban-industrial symbiosis strategies offer a new pathway toward urban energy efficiency and health that have not previously been quantified. Key examples includes the use of waste industrial heat in other co-located industries, and in residential-commercial district heating-cooling systems of cities. To quantify the impact of these strategies: (1) We develop a new data-set of 637 Chinese cities to assess the potential for efficiency and symbiosis across co-located homes, businesses, industries and the energy and construction sectors in the different cities. (2) A multi-scalar urban systems model quantifies trans-boundary CO2 impacts as well as local health benefits of these uniquely urban, co-location-dependent strategies. (3) CO2 impacts are aggregated across the 637 Chinese cities (home to 701 million people) to quantify national CO2 mitigation potential. (4) The local health benefits are modeled specific to each city and mapped geospatially to identify areas where co-benefits between GHG mitigation and health are maximized. Results: A first order conservative analysis of co-location dependent urban symbiosis indicates potential for reducing 6% of China's national total CO2 emissions in a relatively short time period, yielding a new pathway not previously considered in China's energy futures models. The magnitude of these reductions (6%) was similar in magnitude to sector specific industrial, power sector and buildings efficiency strategeies that together contributed 9% CO2 reduction aggregated across the nation. CO2 reductions mapped to the 637 cities ranged from <1% to 40%, depending upon co-location patterns, climate and other features of the cities. The modeled reductions in fossil-fuel use yield reductions in PM-2.5 emissions from <1% to 73%, depending on the city, and avoided annual mortality >40,000 premature deaths (avoided) across all cities. These results demonstrate the contribution urban symbiosis on decarbonization and health co-benefits.

Beyond Solar Fuels: Renewable Energy-Driven Chemistry.

PubMed

Lanzafame, Paola; Abate, Salvatare; Ampelli, Claudio; Genovese, Chiara; Passalacqua, Rosalba; Centi, Gabriele; Perathoner, Siglinda

2017-11-23

The future feasibility of decarbonized industrial chemical production based on the substitution of fossil feedstocks (FFs) with renewable energy (RE) sources is discussed. Indeed, the use of FFs as an energy source has the greatest impact on the greenhouse gas emissions of chemical production. This future scenario is indicated as "solar-driven" or "RE-driven" chemistry. Its possible implementation requires to go beyond the concept of solar fuels, in particular to address two key aspects: i) the use of RE-driven processes for the production of base raw materials, such as olefins, methanol, and ammonia, and ii) the development of novel RE-driven routes that simultaneously realize process and energy intensification, particularly in the direction of a significant reduction of the number of the process steps. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Seafloor doming driven by degassing processes unveils sprouting volcanism in coastal areas.

PubMed

Passaro, Salvatore; Tamburrino, Stella; Vallefuoco, Mattia; Tassi, Franco; Vaselli, Orlando; Giannini, Luciano; Chiodini, Giovanni; Caliro, Stefano; Sacchi, Marco; Rizzo, Andrea Luca; Ventura, Guido

2016-03-01

We report evidences of active seabed doming and gas discharge few kilometers offshore from the Naples harbor (Italy). Pockmarks, mounds, and craters characterize the seabed. These morphologies represent the top of shallow crustal structures including pagodas, faults and folds affecting the present-day seabed. They record upraise, pressurization, and release of He and CO2 from mantle melts and decarbonation reactions of crustal rocks. These gases are likely similar to those that feed the hydrothermal systems of the Ischia, Campi Flegrei and Somma-Vesuvius active volcanoes, suggesting the occurrence of a mantle source variously mixed to crustal fluids beneath the Gulf of Naples. The seafloor swelling and breaching by gas upraising and pressurization processes require overpressures in the order of 2-3 MPa. Seabed doming, faulting, and gas discharge are manifestations of non-volcanic unrests potentially preluding submarine eruptions and/or hydrothermal explosions.

Decentralized energy systems for clean electricity access

NASA Astrophysics Data System (ADS)

Alstone, Peter; Gershenson, Dimitry; Kammen, Daniel M.

2015-04-01

Innovative approaches are needed to address the needs of the 1.3 billion people lacking electricity, while simultaneously transitioning to a decarbonized energy system. With particular focus on the energy needs of the underserved, we present an analytic and conceptual framework that clarifies the heterogeneous continuum of centralized on-grid electricity, autonomous mini- or community grids, and distributed, individual energy services. A historical analysis shows that the present day is a unique moment in the history of electrification where decentralized energy networks are rapidly spreading, based on super-efficient end-use appliances and low-cost photovoltaics. We document how this evolution is supported by critical and widely available information technologies, particularly mobile phones and virtual financial services. These disruptive technology systems can rapidly increase access to basic electricity services and directly inform the emerging Sustainable Development Goals for quality of life, while simultaneously driving action towards low-carbon, Earth-sustaining, inclusive energy systems.

ROCK PHYSICS. Rock physics of fibrous rocks akin to Roman concrete explains uplifts at Campi Flegrei Caldera.

PubMed

Vanorio, Tiziana; Kanitpanyacharoen, Waruntorn

2015-08-07

Uplifts in the Campi Flegrei caldera reach values unsurpassed anywhere in the world (~2 meters). Despite the marked deformation, the release of strain appears delayed. The rock physics analysis of well cores highlights the presence of two horizons, above and below the seismogenic area, underlying a coupled process. The basement is a calc-silicate rock housing hydrothermal decarbonation reactions, which provide lime-rich fluids. The caprock above the seismogenic area has a pozzolanic composition and a fibril-rich matrix that results from lime-pozzolanic reactions. These findings provide evidence for a natural process reflecting that characterizing the cementitious pastes in modern and Roman concrete. The formation of fibrous minerals by intertwining filaments confers shear and tensile strength to the caprock, contributing to its ductility and increased resistance to fracture. Copyright © 2015, American Association for the Advancement of Science.

Developing country finance in a post-2020 global climate agreement

NASA Astrophysics Data System (ADS)

Hannam, Phillip M.; Liao, Zhenliang; Davis, Steven J.; Oppenheimer, Michael

2015-11-01

A central task for negotiators of the post-2020 global climate agreement is to construct a finance regime that supports low-carbon development in developing economies. As power sector investments between developing countries grow, the climate finance regime should incentivize the decarbonization of these major sources of finance by integrating them as a complement to the commitments of developed nations. The emergence of the Asian Infrastructure Investment Bank, South-South Cooperation Fund and other nascent institutions reveal the fissures that exist in rules and norms surrounding international finance in the power sector. Structuring the climate agreement in Paris to credit qualified finance from the developing world could have several advantages, including: (1) encouraging low-carbon cooperation between developing countries; (2) incentivizing emerging investors to prefer low-carbon investments; and (3) enabling more cost-effective attainment of national and global climate objectives. Failure to coordinate on standards now could hinder low-carbon development in the decades to come.

Decarbonizing urban transport in European cities: four cases show possibly high co-benefits

NASA Astrophysics Data System (ADS)

Creutzig, Felix; Mühlhoff, Rainer; Römer, Julia

2012-12-01

Cities worldwide are increasingly becoming agents of climate change mitigation, while simultaneously aiming for other goals, such as improved accessibility and clean air. Based on stakeholder interviews and data analysis, we assess the current state of urban mobility in the four European cities of Barcelona, Malmö, Sofia and Freiburg. We then provide scenarios of increasingly ambitious policy packages, reducing greenhouse gas emissions from urban transport by up to 80% from 2010 to 2040. We find significant concurrent co-benefits in cleaner air, reduced noise ambience, fewer traffic-related injuries and deaths, more physical activity, less congestion and monetary fuel savings. Our scenarios suggest that non-motorized transport, especially bicycles, can occupy high modal shares, particularly in cities with less than 0.5 million inhabitants. We think that this kind of multi-criteria assessment of social costs and benefits is a useful complement to cost-benefit analysis of climate change mitigation measures.

The carbon footprint of global tourism

NASA Astrophysics Data System (ADS)

Lenzen, Manfred; Sun, Ya-Yen; Faturay, Futu; Ting, Yuan-Peng; Geschke, Arne; Malik, Arunima

2018-06-01

Tourism contributes significantly to global gross domestic product, and is forecast to grow at an annual 4%, thus outpacing many other economic sectors. However, global carbon emissions related to tourism are currently not well quantified. Here, we quantify tourism-related global carbon flows between 160 countries, and their carbon footprints under origin and destination accounting perspectives. We find that, between 2009 and 2013, tourism's global carbon footprint has increased from 3.9 to 4.5 GtCO2e, four times more than previously estimated, accounting for about 8% of global greenhouse gas emissions. Transport, shopping and food are significant contributors. The majority of this footprint is exerted by and in high-income countries. The rapid increase in tourism demand is effectively outstripping the decarbonization of tourism-related technology. We project that, due to its high carbon intensity and continuing growth, tourism will constitute a growing part of the world's greenhouse gas emissions.

Shale Gas: Development Opportunities and Challenges

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

Zoback, Mark D.; Arent, Douglas J.

2014-03-01

The use of horizontal drilling and multistage hydraulic fracturing technologies has enabled the production of immense quantities of natural gas, to date principally in North America but increasingly in other countries around the world. The global availability of this resource creates both opportunities and challenges that need to be addressed in a timely and effective manner. There seems little question that rapid shale gas development, coupled with fuel switching from coal to natural gas for power generation, can have beneficial effects on air pollution, greenhouse gas emissions, and energy security in many countries. In this context, shale gas resources representmore » a critically important transition fuel on the path to a decarbonized energy future. For these benefits to be realized, however, it is imperative that shale gas resources be developed with effective environmental safeguards to reduce their impact on land use, water resources, air quality, and nearby communities.« less

Pathways for balancing CO2 emissions and sinks.

PubMed

Walsh, Brian; Ciais, Philippe; Janssens, Ivan A; Peñuelas, Josep; Riahi, Keywan; Rydzak, Felicjan; van Vuuren, Detlef P; Obersteiner, Michael

2017-04-13

In December 2015 in Paris, leaders committed to achieve global, net decarbonization of human activities before 2100. This achievement would halt and even reverse anthropogenic climate change through the net removal of carbon from the atmosphere. However, the Paris documents contain few specific prescriptions for emissions mitigation, leaving various countries to pursue their own agendas. In this analysis, we project energy and land-use emissions mitigation pathways through 2100, subject to best-available parameterization of carbon-climate feedbacks and interdependencies. We find that, barring unforeseen and transformative technological advancement, anthropogenic emissions need to peak within the next 10 years, to maintain realistic pathways to meeting the COP21 emissions and warming targets. Fossil fuel consumption will probably need to be reduced below a quarter of primary energy supply by 2100 and the allowable consumption rate drops even further if negative emissions technologies remain technologically or economically unfeasible at the global scale.

Shock-induced CO2 loss from CaCO3: Implications for early planetary atmospheres

NASA Technical Reports Server (NTRS)

Lange, M. A.; Ahrens, T. J.

1984-01-01

Recovered samples from shock recovery experiments on single crystal calcite were subjected to thermogravimetric analysis to determine the amount of post-shock CO2, the decarbonization interval and the activation energy, for the removal of remaining CO2 in shock-loaded calcite. Comparison of post-shock CO2 with that initially present determines shock-induced CO2 loss as a function of shock pressure. Incipient to complete CO2 loss occurs over a pressure range of approximately 10 to approximately 70 GPa. Optical and scanning electron microscopy reveal structural changes, which are related to the shock-loading. The occurrence of dark, diffuse areas, which can be resolved as highly vesicular areas as observed with a scanning electron microscope are interpreted as representing quenched partial melts, into which shock-released CO2 was injected. The experimental results are used to constrain models of shock-produced, primary CO2 atmospheres on the accreting terrestrial planets.

Drivers of the US CO2 emissions 1997–2013

PubMed Central

Feng, Kuishuang; Davis, Steven J.; Sun, Laixiang; Hubacek, Klaus

2015-01-01

Fossil fuel CO2 emissions in the United States decreased by ∼11% between 2007 and 2013, from 6,023 to 5,377 Mt. This decline has been widely attributed to a shift from the use of coal to natural gas in US electricity production. However, the factors driving the decline have not been quantitatively evaluated; the role of natural gas in the decline therefore remains speculative. Here we analyse the factors affecting US emissions from 1997 to 2013. Before 2007, rising emissions were primarily driven by economic growth. After 2007, decreasing emissions were largely a result of economic recession with changes in fuel mix (for example, substitution of natural gas for coal) playing a comparatively minor role. Energy–climate policies may, therefore, be necessary to lock-in the recent emissions reductions and drive further decarbonization of the energy system as the US economy recovers and grows. PMID:26197104

Seafloor doming driven by degassing processes unveils sprouting volcanism in coastal areas

PubMed Central

Passaro, Salvatore; Tamburrino, Stella; Vallefuoco, Mattia; Tassi, Franco; Vaselli, Orlando; Giannini, Luciano; Chiodini, Giovanni; Caliro, Stefano; Sacchi, Marco; Rizzo, Andrea Luca; Ventura, Guido

2016-01-01

We report evidences of active seabed doming and gas discharge few kilometers offshore from the Naples harbor (Italy). Pockmarks, mounds, and craters characterize the seabed. These morphologies represent the top of shallow crustal structures including pagodas, faults and folds affecting the present-day seabed. They record upraise, pressurization, and release of He and CO2 from mantle melts and decarbonation reactions of crustal rocks. These gases are likely similar to those that feed the hydrothermal systems of the Ischia, Campi Flegrei and Somma-Vesuvius active volcanoes, suggesting the occurrence of a mantle source variously mixed to crustal fluids beneath the Gulf of Naples. The seafloor swelling and breaching by gas upraising and pressurization processes require overpressures in the order of 2–3 MPa. Seabed doming, faulting, and gas discharge are manifestations of non-volcanic unrests potentially preluding submarine eruptions and/or hydrothermal explosions. PMID:26925957

Moving beyond alternative fuel hype to decarbonize transportation

NASA Astrophysics Data System (ADS)

Melton, Noel; Axsen, Jonn; Sperling, Daniel

2016-03-01

In the past three decades, government, industry and other stakeholders have repeatedly been swept up with the ‘fuel du jour’, claiming that a particular alternative fuel vehicle (AFV) technology can succeed in replacing conventional gasoline-powered vehicles. However, AFV technologies have experienced relatively little success, with fossil fuels still accounting for about 95% of global transport energy use. Here, using the US as a case study, we conduct a media analysis to show how society’s attention has skipped among AFV types between 1980 and 2013, including methanol, natural gas, plug-in electric, hybrid electric, hydrogen and biofuels. Although our results provide no indication as to whether hype ultimately has a net positive or negative impact on AFV innovation, we offer several recommendations that governments can follow to move past hype to support significant AFV adoption and displace fossil fuel use in the transportation sector.

Effects of Anode Arc Root Fluctuation on Coating Quality During Plasma Spraying

NASA Astrophysics Data System (ADS)

An, Lian-Tong; Gao, Yang; Sun, Chengqi

2011-06-01

To obtain a coating of high quality, a new type of plasma torch was designed and constructed to increase the stability of the plasma arc and reduce the air entrainment into the plasma jet. The torch, called bi-anode torch, generates an elongated arc with comparatively high arc voltage and low arc fluctuation. Spraying experiments were carried out to compare the quality of coatings deposited by a conventional torch and a bi-anode torch. Alumina coatings and tungsten carbide coatings were prepared to appraise the heating of the sprayed particles in the plasma jets and the entrainment of the surrounding air into the plasma jets, respectively. The results show that anode arc root fluctuation has only a small effect on the melting rate of alumina particles. On the other hand, reduced air entrainment into the plasma jet of the bi-anode torch will drastically reduce the decarbonization of tungsten carbide coatings.

Pathways for balancing CO2 emissions and sinks

PubMed Central

Walsh, Brian; Ciais, Philippe; Janssens, Ivan A.; Peñuelas, Josep; Riahi, Keywan; Rydzak, Felicjan; van Vuuren, Detlef P.; Obersteiner, Michael

2017-01-01

In December 2015 in Paris, leaders committed to achieve global, net decarbonization of human activities before 2100. This achievement would halt and even reverse anthropogenic climate change through the net removal of carbon from the atmosphere. However, the Paris documents contain few specific prescriptions for emissions mitigation, leaving various countries to pursue their own agendas. In this analysis, we project energy and land-use emissions mitigation pathways through 2100, subject to best-available parameterization of carbon-climate feedbacks and interdependencies. We find that, barring unforeseen and transformative technological advancement, anthropogenic emissions need to peak within the next 10 years, to maintain realistic pathways to meeting the COP21 emissions and warming targets. Fossil fuel consumption will probably need to be reduced below a quarter of primary energy supply by 2100 and the allowable consumption rate drops even further if negative emissions technologies remain technologically or economically unfeasible at the global scale. PMID:28406154

The North American Energy System: Chapter 3 of SOCCR-2

NASA Astrophysics Data System (ADS)

Gurney, K. R.; Marcotullio, P. J.; McGlynn, E.; Bruhwiler, L.; Davis, K. J.; Davis, S. J.; Engel-Cox, J.; Field, J.; Gately, C.; Kammen, D. M.; McMahon, J.; Morrow, W.; Torrie, R.

2017-12-01

North America (Canada, Mexico and the United States), has a large and complex energy system, which in this case includes the extraction and conversion of primary energy sources and their storage, transmission, distribution and ultimate end use in the building, transportation and industrial sectors. The presentation assesses the contribution of this energy system to the carbon cycle. The assessment includes the identification of CO2 emissions from fossil fuel use in the different end use, changes over the past 10 years (since the last SOCCR) and the drivers of change. The assessment focuses on our understanding of the energy trends and system feedback dynamics, key drivers of change as a basis for carbon management. The energy systems' carbon emissions from the North American system are placed in global context and a review of scenarios into the future emissions levels, which demonstrate the requirements for de-carbonization in the medium and longer term.

How should support for climate-friendly technologies be designed?

PubMed

Fischer, Carolyn; Torvanger, Asbjørn; Shrivastava, Manish Kumar; Sterner, Thomas; Stigson, Peter

2012-01-01

Stabilizing global greenhouse gas concentrations at levels to avoid significant climate risks will require massive "decarbonization" of all the major economies over the next few decades, in addition to the reduced emissions from other GHGs and carbon sequestration. Achieving the necessary scale of emissions reductions will require a multifaceted policy effort to support a broad array of technological and behavioral changes. Change on this scale will require sound, well-thought-out strategies. In this article, we outline some core principles, drawn from recent social science research, for guiding the design of clean technology policies, with a focus on energy. The market should be encouraged to make good choices: pricing carbon emissions and other environmental damage, removing distorting subsidies and barriers to competition, and supporting RD&D broadly. More specific policies are required to address particular market failures and barriers. For those technologies identified as being particularly desirable, some narrower RD&D policies are available.

The Effects of Varying Crustal Carbonate Composition on Assimilation and CO2 Degassing at Arc Volcanoes

NASA Astrophysics Data System (ADS)

Carter, L. B.; Holmes, A. K.; Dasgupta, R.; Tumiati, S.

2015-12-01

Magma-crustal carbonate interaction and subsequent decarbonation can provide an additional source of CO2 release to the exogenic system superimposed on mantle-derived CO2. Carbonate assimilation at present day volcanoes is often modeled by limestone consumption experiments [1-4]. Eruptive products, however, do not clearly display the characteristic ultracalcic melt compositions produced during limestone-magma interaction [4]. Yet estimated CO2outflux [5] and composition of volcanics in many volcanic systems may allow ~3-17% limestone- or dolostone-assimilated melt contribution. Crystallization may retain ultracalcic melts in pyroxenite cumulates. To extend our completed study on limestone assimilation, here we explore the effect of varying composition from calcite to dolomite on chemical and thermal decarbonation efficiency of crustal carbonates. Piston cylinder experiments at 0.5 GPa and 900-1200 °C demonstrate that residual mineralogy during interaction with magma shifts from CaTs cpx and anorthite/scapolite in the presence of calcite to Di cpx and Fo-rich olivine with dolomite. Silica-undersaturated melts double in magnesium content, while maintaining high (>30 wt.%) CaO values. At high-T, partial thermal breakdown of dolomite into periclase and CO2 is minimal (<5%) suggesting that in the presence of magma, CO2 is primarily released due to assimilation. Assimilated melts at identical P-T conditions depict similarly high volatile contents (10-20 wt.% by EMPA deficit at 0.5 GPa, 1150 °C with hydrous basalt) with calcite or dolomite. Analysis of the coexisting fluid phase indicates the majority of water is dissolved in the melt, while CO2 released from the carbonate is preferentially partitioned into the vapor. This suggests that although assimilated melts have a higher CO2 solubility, most of the CO2can easily degas from the vapor phase at arc volcanoes, possibly more so at volcanic plumbing systems traversing dolomite [8]. [1]Conte et al 2009 EuJMin (21) 763-782; [2]Iacono-Marziano et al 2008 CMP (155) 719-738; [3]Mollo et al 2010 Lithos (114) 503-514; [4]Carter and Dasgupta 2015 EPSL (427) 202-214; [5]Burton et al 2013 RevMinGeochem (75) 323-254; [6]Balassone et al 2013 Lithos (160-161) 84-97; [7]Di Rocco et al. 2012 JPet (53) 2307-2332; [8]Del Moro et al 2001 JVGR (112) 15-24.

P-V-T equation of state of CaCO3 aragonite to 29 GPa and 1673 K: In situ X-ray diffraction study

NASA Astrophysics Data System (ADS)

Litasov, Konstantin D.; Shatskiy, Anton; Gavryushkin, Pavel N.; Bekhtenova, Altyna E.; Dorogokupets, Peter I.; Danilov, Boris S.; Higo, Yuji; Akilbekov, Abdirash T.; Inerbaev, Talgat M.

2017-04-01

Pressure-volume-temperature relations have been measured to 29 GPa and 1673 K for CaCO3 aragonite using synchrotron X-ray diffraction with a multianvil apparatus at the 'SPring-8' facility. A least-squares fit of the room-temperature compression data to the Vinet-Rydberg equation of state (EOS) yielded KT0 = 65.7 ± 0.8 GPa and KT' = 5.1 ± 0.1, with fixed V0 = 227.11 Å3. Further analysis of the high-temperature compression data led to the temperature derivative of the bulk modulus (∂KT/∂T)P = -0.016 ± 0.001 GPa/K and zero-pressure thermal expansion α = a0 + a1T with a0 = 4.98 (22) × 10-5 K-1 and a1 = 2.81(38) × 10-8 K-2. The Mie-Gruneisen-Debye approach revealed the Gruneisen parameter γ0 = 1.39 at a fixed Debye temperature θ0 = 516 K and the parameter q = 1. Analysis of axial compressibility and thermal expansion indicates that the c-axis is two times more compressible than the b-axis and four times more compressible than the a-axis, whereas zero-pressure thermal expansion of the a-axis (a0a = 2.6 × 10-5 K-1 and a1a = 2.3 × 10-8 K-2) is weaker than that of the b-axis axis (a0b = 6.3 × 10-5 K-1 and a1b = 0.1 × 10-8 K-2) and c-axis axis (a0c = 5.2 × 10-5 K-1 and a1c = 9.5 × 10-8 K-2). A full set of thermodynamic parameters (including heat capacity, enthalpy and free energy) for aragonite and updated equations of state for magnesite and siderite was obtained using the Kunc-Einstein approach. The new EOS parameters were used for thermodynamic calculations for aragonite decarbonation reactions. The present thermal EOS provides accurate calculations of aragonite density to deep mantle. Decarbonation of subducting oceanic crust containing 2 wt% aragonite would result in a 0.5% density reduction at 30 GPa and 1273 K. Aragonite becomes denser than magnesite at pressures about 16 GPa along the 1500 K isotherm and at 9 GPa along the 298 K isotherm.

Numerical analysis on infiltration-driven decarbonation during skarnification

NASA Astrophysics Data System (ADS)

Chu, X.; Lee, C. T.; Dasgupta, R.

2017-12-01

Interaction of arc magmas with carbonate sequences on active margins leads to contact metamorphism and metasomatism by infiltrating magmatic fluids. This skarnification process releases CO2 to the metasomatic fluids, which transport carbon to shallow reservoirs and can affect the long-term carbon budget in the exogenic system [1]. In this study, we apply a self-consistent 1D finite difference model to an impure marble consisting of quartz and calcite, in a similar scheme as ref [2]. The Darcian flow is modeled with a fixed boundary condition of water influx, taking into account the reaction kinetics [3,4] and pore space compaction. The modeling results show that the reaction front lags the fluid infiltration front and propagates at the rate scaling with: = k × [infiltrating fluid flux] / [reactant amount], where k is a function of the reaction kinetics and rock rheology. The reaction front does not advance until one reactant is exhausted; thus a protolith assemblage of 50:50 quartz:calcite has the slowest-moving reaction front. The steady-state carbon flux scales with the distance of reaction front to comply with mass conservation, and thus yields a linear relationship with the infiltrating flux and is largely independent of the protolith quartz:calcite ratio. Assuming that the rate of global magma emplacement on the continental arcs is 3 km3/yr [5], the arc magmas exsolve 5 vol.% water as they crystallize, and 40% of such magmas intrude carbonate sequences, the total steady-state carbon flux due to skarnification is 0.2 Tmol/yr. By contrast, Mount Etna alone emits carbon up to 0.2 Tmol/yr, most of which is the product of magma-carbonate interaction [6]. We note that the infiltration of pure water produces a wollastonite marble; natural metasomatic fluid is saturated with silica and other components, which leads to greater decarbonation and the formation of calc-silicate skarn. Wallrock assimilation also adds to the carbon flux from arcs, so the simplified analysis should be viewed as a lower-limit estimate. [1] Lee et al (2013) Geosphere 9. [2] Balashov & Yardley (1998) Am J Sci 298. [3] Joesten & Fisher (1988) GSA Bull 100. [4] Lasaga & Rye (1993) Am J Sci 293. [5] Crisp (1984) J Volcanol Geotherm Res 20. [6] Allard et al (1991) Nature 351.

Solar energy in the context of energy use, energy transportation and energy storage.

PubMed

MacKay, David J C

2013-08-13

Taking the UK as a case study, this paper describes current energy use and a range of sustainable energy options for the future, including solar power and other renewables. I focus on the area involved in collecting, converting and delivering sustainable energy, looking in particular detail at the potential role of solar power. Britain consumes energy at a rate of about 5000 watts per person, and its population density is about 250 people per square kilometre. If we multiply the per capita energy consumption by the population density, then we obtain the average primary energy consumption per unit area, which for the UK is 1.25 watts per square metre. This areal power density is uncomfortably similar to the average power density that could be supplied by many renewables: the gravitational potential energy of rainfall in the Scottish highlands has a raw power per unit area of roughly 0.24 watts per square metre; energy crops in Europe deliver about 0.5 watts per square metre; wind farms deliver roughly 2.5 watts per square metre; solar photovoltaic farms in Bavaria, Germany, and Vermont, USA, deliver 4 watts per square metre; in sunnier locations, solar photovoltaic farms can deliver 10 watts per square metre; concentrating solar power stations in deserts might deliver 20 watts per square metre. In a decarbonized world that is renewable-powered, the land area required to maintain today's British energy consumption would have to be similar to the area of Britain. Several other high-density, high-consuming countries are in the same boat as Britain, and many other countries are rushing to join us. Decarbonizing such countries will only be possible through some combination of the following options: the embracing of country-sized renewable power-generation facilities; large-scale energy imports from country-sized renewable facilities in other countries; population reduction; radical efficiency improvements and lifestyle changes; and the growth of non-renewable low-carbon sources, namely 'clean' coal, 'clean' gas and nuclear power. If solar is to play a large role in the future energy system, then we need new methods for energy storage; very-large-scale solar either would need to be combined with electricity stores or it would need to serve a large flexible demand for energy that effectively stores useful energy in the form of chemicals, heat, or cold.

Carbon dioxide generation and drawdown during active orogenesis of siliciclastic rocks in the Southern Alps, New Zealand

NASA Astrophysics Data System (ADS)

Menzies, Catriona D.; Wright, Sarah L.; Craw, Dave; James, Rachael H.; Alt, Jeffrey C.; Cox, Simon C.; Pitcairn, Iain K.; Teagle, Damon A. H.

2018-01-01

Collisional mountain building influences the global carbon cycle through release of CO2 liberated by metamorphic reactions and promoting mechanical erosion that in turn increases chemical weathering and drawdown of atmospheric CO2. The Southern Alps is a carbonate-poor, siliciclastic mountain belt associated with the active Australian Pacific plate boundary. On-going, rapid tectonic uplift, metamorphism and hydrothermal activity are mobilising carbon. Here we use carbon isotope measurements of hot spring fluids and gases, metamorphic host rocks, and carbonate veins to establish a metamorphic carbon budget. We identify three major sources for CO2 within the Southern Alps: (1) the oxidation of graphite; (2) consumption of calcite by metamorphic reactions at the greenschist-amphibolite facies boundary, and (3) the dissolution of groundmass and vein-hosted calcite. There is only a minor component of mantle CO2 arising on the Alpine Fault. Hot springs have molar HCO3-/Ca2+ ∼9, which is substantially higher than produced by the dissolution of calcite indicating that deeper metamorphic processes must dominate. The total CO2 flux to the near surface environment in the high uplift region of the Southern Alps is estimated to be ∼6.4 × 108 mol/yr. Approximately 87% of this CO2 is sourced from coupled graphite oxidation (25%) and disseminated calcite decarbonation (62%) reactions during prograde metamorphism. Dissolution of calcite and mantle-derived CO2 contribute ∼10% and ∼3% respectively. In carbonate-rich orogens CO2 production is dominated by metamorphic decarbonation of limestones. The CO2 flux to the atmosphere from degassing of hot springs in the Southern Alps is 1.9 to 3.2 × 108 mol/yr, which is 30-50% of the flux to the near surface environment. By contrast, the drawdown of CO2 through surficial chemical weathering ranges between 2.7 and 20 × 109 mol/yr, at least an order of magnitude greater than the CO2 flux to the atmosphere from this orogenic belt. Thus, siliciclastic mountain belts like the Southern Alps are net sinks for atmospheric CO2, in contrast to orogens involving abundant carbonate rocks, such as the Himalaya, that are net CO2 sources.

The heat capacity of a natural monticellite and phase equilibria in the system CaO-MgO-SiO2-CO2

USGS Publications Warehouse

Sharp, Z.D.; Essene, E.J.; Anovitz, Lawrence M.; Metz, G.W.; Westrum, E.F.; Hemingway, B.S.; Valley, J.W.

1986-01-01

The heat capacity of a natural monticellite (Ca1.00Mg.09Fe.91Mn.01Si0.99O3.99) measured between 9.6 and 343 K using intermittent-heating, adiabatic calorimetry yields Cp0(298) and S2980 of 123.64 ?? 0.18 and 109.44 ?? 0.16 J ?? mol-1 K-1 respectively. Extrapolation of this entropy value to end-member monticellite results in an S0298 = 108.1 ?? 0.2 J ?? mol-1 K-1. High-temperature heat-capacity data were measured between 340-1000 K with a differential scanning calorimeter. The high-temperature data were combined with the 290-350 K adiabatic values, extrapolated to 1700 K, and integrated to yield the following entropy equation for end-member monticellite (298-1700 K): ST0(J ?? mol-1 K-1) = S2980 + 164.79 In T + 15.337 ?? 10-3 T + 22.791 ?? 105 T-2 - 968.94. Phase equilibria in the CaO-MgO-SiO2 system were calculated from 973 to 1673 K and 0 to 12 kbar with these new data combined with existing data for akermanite (Ak), diopside (Di), forsterite (Fo), merwinite (Me) and wollastonite (Wo). The location of the calculated reactions involving the phases Mo and Fo is affected by their mutual solid solution. A best fit of the thermodynamically generated curves to all experiments is made when the S0298 of Me is 250.2 J ?? mol-1 K-1 less than the measured value of 253.2 J ?? mol-1 K-1. A best fit to the reversals for the solid-solid and decarbonation reactions in the CaO-MgO-SiO2-CO2 system was obtained with the ??G0298 (kJ ?? mole-1) for the phases Ak(-3667), Di(-3025), Fo(-2051), Me(-4317) and Mo(-2133). The two invariant points - Wo and -Fo for the solid-solid reactions are located at 1008 ?? 5 K and 6.3 ?? 0.1 kbar, and 1361 ?? 10 K and 10.2 ?? 0.2 kbar respectively. The location of the thermodynamically generated curves is in excellent agreement with most experimental data on decarbonation equilibria involving these phases. ?? 1986.

Emergent dynamics of the climate-economy system in the Anthropocene.

PubMed

Kellie-Smith, Owen; Cox, Peter M

2011-03-13

Global CO(2) emissions are understood to be the largest contributor to anthropogenic climate change, and have, to date, been highly correlated with economic output. However, there is likely to be a negative feedback between climate change and human wealth: economic growth is typically associated with an increase in CO(2) emissions and global warming, but the resulting climate change may lead to damages that suppress economic growth. This climate-economy feedback is assumed to be weak in standard climate change assessments. When the feedback is incorporated in a transparently simple model it reveals possible emergent behaviour in the coupled climate-economy system. Formulae are derived for the critical rates of growth of global CO(2) emissions that cause damped or long-term boom-bust oscillations in human wealth, thereby preventing a soft landing of the climate-economy system. On the basis of this model, historical rates of economic growth and decarbonization appear to put the climate-economy system in a potentially damaging oscillatory regime.

Reducing greenhouse gas emissions for climate stabilization: framing regional options.

PubMed

Olabisi, Laura Schmitt; Reich, Peter B; Johnson, Kris A; Kapuscinski, Anne R; Su, Sangwon H; Wilson, Elizabeth J

2009-03-15

The Intergovernmental Panel on Climate Change (IPCC) has stated that stabilizing atmospheric CO2 concentrations will require reduction of global greenhouse gas (GHG) emissions by as much as 80% by 2050. Subnational efforts to cut emissions will inform policy development nationally and globally. We projected GHG mitigation strategies for Minnesota, which has adopted a strategic goal of 80% emissions reduction by 2050. A portfolio of conservation strategies, including electricity conservation, increased vehicle fleet fuel efficiency, and reduced vehicle miles traveled, is likely the most cost-effective option for Minnesota and could reduce emissions by 18% below 2005 levels. An 80% GHG reduction would require complete decarbonization of the electricity and transportation sectors, combined with carbon capture and sequestration at power plants, or deep cuts in other relatively more intransigent GHG-emitting sectors. In order to achieve ambitious GHG reduction goals, policymakers should promote aggressive conservation efforts, which would probably have negative net costs, while phasing in alternative fuels to replace coal and motor gasoline over the long-term.

Translational Science for Energy and Beyond.

PubMed

McKone, James R; Crans, Debbie C; Martin, Cheryl; Turner, John; Duggal, Anil R; Gray, Harry B

2016-09-19

A clear challenge for the coming decades is decreasing the carbon intensity of the global energy supply while simultaneously accommodating a rapid worldwide increase in power demand. Meeting this challenge of providing abundant, clean energy undoubtedly requires synergistic efforts between basic and applied researchers in the chemical sciences to develop and deploy new technologies. Among the available options, solar energy is one of the promising targets because of the high abundance of solar photons over much of the globe. Similarly, decarbonization of the global energy supply will require clean sources of hydrogen to use as reducing equivalents for fuel and chemical feedstocks. In this report, we discuss the importance of translational research-defined as work that explicitly targets basic discovery as well as technology development-in the context of photovoltaics and solar fuels. We focus on three representative research programs encompassing translational research in government, industry, and academia. We then discuss more broadly the benefits and challenges of translational research models and offer recommendations for research programs that address societal challenges in the energy sector and beyond.

U.S. Natural Gas System Methane Emissions: State of Knowledge from LCAs, Inventories, and Atmospheric Measurements (Presentation)

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

Heath, G.

Natural gas (NG) is a potential "bridge fuel" during transition to a decarbonized energy system: It emits less carbon dioxide during combustion than other fossil fuels and can be used in many industries. However, because of the high global warming potential of methane (CH4, the major component of NG), climate benefits from NG use depend on system leakage rates. Some recent estimates of leakage have challenged the benefits of switching from coal to NG, a large near-term greenhouse gas (GHG) reduction opportunity. During this presentation, Garvin will review evidence from multiple perspectives - life cycle assessments (LCAs), inventories and measurementsmore » - about NG leakage in the US. Particular attention will be paid to a recent article in Science magazine which reviewed over 20 years of published measurements to better understand what we know about total methane emissions and those from the oil and gas sectors. Scientific and policy implications of the state of knowledge will be discussed.« less

A regenerative elastocaloric heat pump

NASA Astrophysics Data System (ADS)

Tušek, Jaka; Engelbrecht, Kurt; Eriksen, Dan; Dall'Olio, Stefano; Tušek, Janez; Pryds, Nini

2016-10-01

A large fraction of global energy use is for refrigeration and air-conditioning, which could be decarbonized if efficient renewable energy technologies could be found. Vapour-compression technology remains the most widely used system to move heat up the temperature scale after more than 100 years; however, caloric-based technologies (those using the magnetocaloric, electrocaloric, barocaloric or elastocaloric effect) have recently shown a significant potential as alternatives to replace this technology due to high efficiency and the use of green solid-state refrigerants. Here, we report a regenerative elastocaloric heat pump that exhibits a temperature span of 15.3 K on the water side with a corresponding specific heating power up to 800 W kg-1 and maximum COP (coefficient-of-performance) values of up to 7. The efficiency and specific heating power of this device exceeds those of other devices based on caloric effects. These results open up the possibility of using the elastocaloric effect in various cooling and heat-pumping applications.

Targeted opportunities to address the climate-trade dilemma in China

NASA Astrophysics Data System (ADS)

Liu, Zhu; Davis, Steven J.; Feng, Kuishuang; Hubacek, Klaus; Liang, Sai; Anadon, Laura Diaz; Chen, Bin; Liu, Jingru; Yan, Jinyue; Guan, Dabo

2016-02-01

International trade has become the fastest growing driver of global carbon emissions, with large quantities of emissions embodied in exports from emerging economies. International trade with emerging economies poses a dilemma for climate and trade policy: to the extent emerging markets have comparative advantages in manufacturing, such trade is economically efficient and desirable. However, if carbon-intensive manufacturing in emerging countries such as China entails drastically more CO2 emissions than making the same product elsewhere, then trade increases global CO2 emissions. Here we show that the emissions embodied in Chinese exports, which are larger than the annual emissions of Japan or Germany, are primarily the result of China’s coal-based energy mix and the very high emissions intensity (emission per unit of economic value) in a few provinces and industry sectors. Exports from these provinces and sectors therefore represent targeted opportunities to address the climate-trade dilemma by either improving production technologies and decarbonizing the underlying energy systems or else reducing trade volumes.

Energy access and sustainable development

NASA Astrophysics Data System (ADS)

Kammen, Daniel M.; Alstone, Peter; Gershenson, Dimitry

2015-03-01

With 1.4 billion people lacking electricity to light their homes and provide other basic services, or to conduct business, and all of humanity (and particularly the poor) are in need of a decarbonized energy system can close the energy access gap and protect the global climate system. With particular focus on addressing the energy needs of the underserved, we present an analytical framework informed by historical trends and contemporary technological, social, and institutional conditions that clarifies the heterogeneous continuum of centralized on-grid electricity, autonomous mini- or community grids, and distributed, individual energy services. We find that the current day is a unique moment of innovation in decentralized energy networks based on super-efficient end-use technology and low-cost photovoltaics, supported by rapidly spreading information technology, particularly mobile phones. Collectively these disruptive technology systems could rapidly increase energy access, contributing to meeting the Millennium Development Goals for quality of life, while simultaneously driving action towards low-carbon, Earth-sustaining, energy systems.

Aligning corporate greenhouse-gas emissions targets with climate goals

NASA Astrophysics Data System (ADS)

Krabbe, Oskar; Linthorst, Giel; Blok, Kornelis; Crijns-Graus, Wina; van Vuuren, Detlef P.; Höhne, Niklas; Faria, Pedro; Aden, Nate; Pineda, Alberto Carrillo

2015-12-01

Corporate climate action is increasingly considered important in driving the transition towards a low-carbon economy. For this, it is critical to ensure translation of global goals to greenhouse-gas (GHG) emissions reduction targets at company level. At the moment, however, there is a lack of clear methods to derive consistent corporate target setting that keeps cumulative corporate GHG emissions within a specific carbon budget (for example, 550-1,300 GtCO2 between 2011 and 2050 for the 2 °C target). Here we propose a method for corporate emissions target setting that derives carbon intensity pathways for companies based on sectoral pathways from existing mitigation scenarios: the Sectoral Decarbonization Approach (SDA). These company targets take activity growth and initial performance into account. Next to target setting on company level, the SDA can be used by companies, policymakers, investors or other stakeholders as a benchmark for tracking corporate climate performance and actions, providing a mechanism for corporate accountability.

Aggressive Strategies for Residential Energy and Carbon Savings by 2025

NASA Astrophysics Data System (ADS)

Ling, F. H.; Kammen, D. M.

2004-12-01

Energy efficiency technologies and practices have long been recognized as a low-cost, often least cost, option that can be deployed widely throughout the economy (Steve Nadel, 2002; Donald A. Hanson and John A. Laitner, 2003). We are engaged in a review of technology-based energy savings options throughout the U. S. economy with a joint focus on both immediate savings opportunities and long-term strategies for accelerating the innovation process and pipeline. For the near term, we developed scenarios based on available 'off the shelf' technologies and practices for achieving minimum energy consumption in lighting, standby power in electronics, and miscellaneous end-uses in the U.S. residential sector. In the business-as-usual (BAU) case, energy consumption continues to grow despite innovations at a current rate of 1.7 percent/year (Laitner, 2004). Nevertheless, the need for developing new energy supplies can be mitigated through the use of 'best current technologies' as the industry norm in 2025. Figure 1 (see URL below) shows this reduction in energy consumption and greenhouse gas emissions. The BAU model corresponds to the current rate of 'decarbonization' in the overall U.S. economy (Energy Information Administration, 2004). Over a twenty-year period, about 2 billion metric tons of carbon dioxide and 30 quads of primary fuel could be saved through the introduction of "best current technology" with the greatest reductions in the area of lighting technologies. In 2025, 1.5 quads of primary energy is saved with the breakdown in end-use electricity saved as follows: 113 TWh (0.39 quads), 70.8 TWh (0.24 quads), and 62 TWh (0.21 quads) for residential lighting, appliance standards, and standby power respectively. In addition, there is empirical evidence from specific technology sectors, from statewide programs in California, as well as on theoretical grounds (Laitner, 2004) that innovation and decarbonization rates of 3 to 5 percent/year have at times been, and could again be achieved. While such high rates of innovation do not usually sustain themselves for more than a few years, innovation rates higher than the current 1.7 percent/year are also explored in this study. Acknowledgement: Alliance to Save Energy (ASE) and Energy Foundation References: Energy Information Administration. "Annual Energy Outlook 2004." Washington, DC: U.S. Department of Energy, 2004. Hanson, Donald A. and Laitner, John A. "Skip". "An Integrated Analysis of Policies That Increase Investments in Advanced Energy-Efficient/Low-Carbon Technologies." Energy Economics, 2003. Laitner, J. A. "How far energy efficiency." 2004. Nadel, Steve. "Appliance and Equipment Efficiency Standards." Annual Reviews, 2002.

Designing low-carbon power systems for Great Britain in 2050 that are robust to the spatiotemporal and inter-annual variability of weather

NASA Astrophysics Data System (ADS)

Zeyringer, Marianne; Price, James; Fais, Birgit; Li, Pei-Hao; Sharp, Ed

2018-05-01

The design of cost-effective power systems with high shares of variable renewable energy (VRE) technologies requires a modelling approach that simultaneously represents the whole energy system combined with the spatiotemporal and inter-annual variability of VRE. Here, we soft-link a long-term energy system model, which explores new energy system configurations from years to decades, with a high spatial and temporal resolution power system model that captures VRE variability from hours to years. Applying this methodology to Great Britain for 2050, we find that VRE-focused power system design is highly sensitive to the inter-annual variability of weather and that planning based on a single year can lead to operational inadequacy and failure to meet long-term decarbonization objectives. However, some insights do emerge that are relatively stable to weather-year. Reinforcement of the transmission system consistently leads to a decrease in system costs while electricity storage and flexible generation, needed to integrate VRE into the system, are generally deployed close to demand centres.

Equatorial convergence of India and early Cenozoic climate trends

PubMed Central

Kent, Dennis V.; Muttoni, Giovanni

2008-01-01

India's northward flight and collision with Asia was a major driver of global tectonics in the Cenozoic and, we argue, of atmospheric CO2 concentration (pCO2) and thus global climate. Subduction of Tethyan oceanic crust with a carpet of carbonate-rich pelagic sediments deposited during transit beneath the high-productivity equatorial belt resulted in a component flux of CO2 delivery to the atmosphere capable to maintain high pCO2 levels and warm climate conditions until the decarbonation factory shut down with the collision of Greater India with Asia at the Early Eocene climatic optimum at ≈50 Ma. At about this time, the India continent and the highly weatherable Deccan Traps drifted into the equatorial humid belt where uptake of CO2 by efficient silicate weathering further perturbed the delicate equilibrium between CO2 input to and removal from the atmosphere toward progressively lower pCO2 levels, thus marking the onset of a cooling trend over the Middle and Late Eocene that some suggest triggered the rapid expansion of Antarctic ice sheets at around the Eocene-Oligocene boundary. PMID:18809910

Syn-deformational features of Carlin-type Au deposits

USGS Publications Warehouse

Peters, S.G.

2004-01-01

Syn-deformational ore deposition played an important role in some Carlin-type Au deposits according to field and laboratory evidence, which indicates that flow of Au-bearing fluids was synchronous with regional-scale deformation events. Gold-related deformation events linked to ore genesis were distinct from high-level, brittle deformation that is typical of many epithermal deposits. Carlin-type Au deposits, with brittle-ductile features, most likely formed during tectonic events that were accompanied by significant fluid flow. Interactive deformation-fluid processes involved brittle-ductile folding, faulting, shearing, and gouge development that were focused along illite-clay and dissolution zones caused by hydrothermal alteration. Alteration along these deformation zones resulted in increased porosity and enhancement of fluid flow, which resulted in decarbonated, significant dissolution, collapse, and volume and mass reduction. Carlin-type Au deposits commonly are hosted in Paleozoic and Mesozoic sedimentary rocks (limestone, siltstone, argillite, shale, and quartzite) on the margins of cratons. The sedimentary basins containing the host rocks underwent tectonic events that influenced the development of stratabound, structurally controlled orebodies. Published by Elsevier Ltd.

Opportunities for Decarbonizing Existing U.S. Coal-Fired Power Plants via CO2 Capture, Utilization and Storage.

PubMed

Zhai, Haibo; Ou, Yang; Rubin, Edward S

2015-07-07

This study employs a power plant modeling tool to explore the feasibility of reducing unit-level emission rates of CO2 by 30% by retrofitting carbon capture, utilization, and storage (CCUS) to existing U.S. coal-fired electric generating units (EGUs). Our goal is to identify feasible EGUs and their key attributes. The results indicate that for about 60 gigawatts of the existing coal-fired capacity, the implementation of partial CO2 capture appears feasible, though its cost is highly dependent on the unit characteristics and fuel prices. Auxiliary gas-fired boilers can be employed to power a carbon capture process without significant increases in the cost of electricity generation. A complementary CO2 emission trading program can provide additional economic incentives for the deployment of CCS with 90% CO2 capture. Selling and utilizing the captured CO2 product for enhanced oil recovery can further accelerate CCUS deployment and also help reinforce a CO2 emission trading market. These efforts would allow existing coal-fired EGUs to continue to provide a significant share of the U.S. electricity demand.

Equatorial convergence of India and early Cenozoic climate trends.

PubMed

Kent, Dennis V; Muttoni, Giovanni

2008-10-21

India's northward flight and collision with Asia was a major driver of global tectonics in the Cenozoic and, we argue, of atmospheric CO(2) concentration (pCO(2)) and thus global climate. Subduction of Tethyan oceanic crust with a carpet of carbonate-rich pelagic sediments deposited during transit beneath the high-productivity equatorial belt resulted in a component flux of CO(2) delivery to the atmosphere capable to maintain high pCO(2) levels and warm climate conditions until the decarbonation factory shut down with the collision of Greater India with Asia at the Early Eocene climatic optimum at approximately 50 Ma. At about this time, the India continent and the highly weatherable Deccan Traps drifted into the equatorial humid belt where uptake of CO(2) by efficient silicate weathering further perturbed the delicate equilibrium between CO(2) input to and removal from the atmosphere toward progressively lower pCO(2) levels, thus marking the onset of a cooling trend over the Middle and Late Eocene that some suggest triggered the rapid expansion of Antarctic ice sheets at around the Eocene-Oligocene boundary.

More homogeneous wind conditions under strong climate change decrease the potential for inter-state balancing of electricity in Europe

NASA Astrophysics Data System (ADS)

Wohland, Jan; Reyers, Mark; Weber, Juliane; Witthaut, Dirk

2017-11-01

Limiting anthropogenic climate change requires the fast decarbonization of the electricity system. Renewable electricity generation is determined by the weather and is hence subject to climate change. We simulate the operation of a coarse-scale fully renewable European electricity system based on downscaled high-resolution climate data from EURO-CORDEX. Following a high-emission pathway (RCP8.5), we find a robust but modest increase (up to 7 %) of backup energy in Europe through the end of the 21st century. The absolute increase in the backup energy is almost independent of potential grid expansion, leading to the paradoxical effect that relative impacts of climate change increase in a highly interconnected European system. The increase is rooted in more homogeneous wind conditions over Europe resulting in intensified simultaneous generation shortfalls. Individual country contributions to European generation shortfall increase by up to 9 TWh yr-1, reflecting an increase of up to 4 %. Our results are strengthened by comparison with a large CMIP5 ensemble using an approach based on circulation weather types.

Translational Science for Energy and Beyond

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

McKone, James R.; Crans, Debbie C.; Martin, Cheryl

A clear challenge for the coming decades is decreasing the carbon intensity of the global energy supply while simultaneously accommodating a rapid worldwide increase in power demand. Meeting this challenge of providing abundant, clean energy undoubtedly requires synergistic efforts between basic and applied researchers in the chemical sciences to develop and deploy new technologies. Among the available options, solar energy is one of the promising targets because of the high abundance of solar photons over much of the globe. Similarly, decarbonization of the global energy supply will require clean sources of hydrogen to use as reducing equivalents for fuel andmore » chemical feedstocks. In this report, we discuss the importance of translational research -- defined as work that explicitly targets basic discovery as well as technology development -- in the context of photovoltaics and solar fuels. We focus on three representative research programs encompassing translational research in government, industry, and academia. We then discuss more broadly the benefits and challenges of translational research models and offer recommendations for research programs that address societal challenges in the energy sector and beyond.« less

Application of hybrid life cycle approaches to emerging energy technologies--the case of wind power in the UK.

PubMed

Wiedmann, Thomas O; Suh, Sangwon; Feng, Kuishuang; Lenzen, Manfred; Acquaye, Adolf; Scott, Kate; Barrett, John R

2011-07-01

Future energy technologies will be key for a successful reduction of man-made greenhouse gas emissions. With demand for electricity projected to increase significantly in the future, climate policy goals of limiting the effects of global atmospheric warming can only be achieved if power generation processes are profoundly decarbonized. Energy models, however, have ignored the fact that upstream emissions are associated with any energy technology. In this work we explore methodological options for hybrid life cycle assessment (hybrid LCA) to account for the indirect greenhouse gas (GHG) emissions of energy technologies using wind power generation in the UK as a case study. We develop and compare two different approaches using a multiregion input-output modeling framework - Input-Output-based Hybrid LCA and Integrated Hybrid LCA. The latter utilizes the full-sized Ecoinvent process database. We discuss significance and reliability of the results and suggest ways to improve the accuracy of the calculations. The comparison of hybrid LCA methodologies provides valuable insight into the availability and robustness of approaches for informing energy and environmental policy.

Nested barriers to low-carbon infrastructure investment

NASA Astrophysics Data System (ADS)

Granoff, Ilmi; Hogarth, J. Ryan; Miller, Alan

2016-12-01

Low-carbon, 'green' economic growth is necessary to simultaneously improve human welfare and avoid the worst impacts of climate change and environmental degradation. Infrastructure choices underpin both the growth and the carbon intensity of the economy. This Perspective explores the barriers to investing in low-carbon infrastructure and some of the policy levers available to overcome them. The barriers to decarbonizing infrastructure 'nest' within a set of barriers to infrastructure development more generally that cause spending on infrastructure--low-carbon or not--to fall more than 70% short of optimal levels. Developing countries face additional barriers such as currency and political risks that increase the investment gap. Low-carbon alternatives face further barriers, such as commercialization risk and financial and public institutions designed for different investment needs. While the broader barriers to infrastructure investment are discussed in other streams of literature, they are often disregarded in literature on renewable energy diffusion or climate finance, which tends to focus narrowly on the project costs of low- versus high-carbon options. We discuss how to overcome the barriers specific to low-carbon infrastructure within the context of the broader infrastructure gap.

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

Balakrishnan, Madhesan; Sacia, Eric R.; Sreekumar, Sanil

Decarbonizing the transportation sector is critical to achieving global climate change mitigation. Although biofuels will play an important role in conventional gasoline and diesel applications, bioderived solutions are particularly important in jet fuels and lubricants, for which no other viable renewable alternatives exist. Producing compounds for jet fuel and lubricant base oil applications often requires upgrading fermentation products, such as alcohols and ketones, to reach the appropriate molecular-weight range. Ketones possess both electrophilic and nucleophilic functionality, which allows them to be used as building blocks similar to alkenes and aromatics in a petroleum refining complex. Here, we develop a methodmore » for selectively upgrading biomass-derived alkyl methyl ketones with >95% yields into trimer condensates, which can then be hydrodeoxygenated in near-quantitative yields to give a new class of cycloalkane compounds. The basic chemistry developed here can be tailored for aviation fuels as well as lubricants by changing the production strategy. We demonstrate that a sugarcane biorefinery could use natural synergies between various routes to produce a mixture of lubricant base oils and jet fuels that achieve net life-cycle greenhouse gas savings of up to 80%.« less

The High Field Path to Practical Fusion Energy

NASA Astrophysics Data System (ADS)

Mumgaard, Robert; Whyte, D.; Greenwald, M.; Hartwig, Z.; Brunner, D.; Sorbom, B.; Marmar, E.; Minervini, J.; Bonoli, P.; Irby, J.; Labombard, B.; Terry, J.; Vieira, R.; Wukitch, S.

2017-10-01

We propose a faster, lower cost development path for fusion energy enabled by high temperature superconductors, devices at high magnetic field, innovative technologies and modern approaches to technology development. Timeliness, scale, and economic-viability are the drivers for fusion energy to combat climate change and aid economic development. The opportunities provided by high-temperature superconductors, innovative engineering and physics, and new organizational structures identified over the last few years open new possibilities for realizing practical fusion energy that could meet mid-century de-carbonization needs. We discuss re-factoring the fusion energy development path with an emphasis on concrete risk retirement strategies utilizing a modular approach based on the high-field tokamak that leverages the broader tokamak physics understanding of confinement, stability, and operational limits. Elements of this plan include development of high-temperature superconductor magnets, simplified immersion blankets, advanced long-leg divertors, a compact divertor test tokamak, efficient current drive, modular construction, and demountable magnet joints. An R&D plan culminating in the construction of an integrated pilot plant and test facility modeled on the ARC concept is presented.

Quaternary fault-controlled volcanic vents and crustal thinning: new insights from the magma-rich Tyrrhenian passive margin (Italy)

NASA Astrophysics Data System (ADS)

Cardello, Giovanni Luca; Conti, Alessia; Consorti, Lorenzo; Do Couto, Damien

2017-04-01

The discover of monogenic Quaternary volcanic vents, that were recently mapped along major fault zones both inland and offshore the Tyrrhenian magma-rich passive margin, poses questions about: timing and role they had into Plio-Pleistocene crustal thinning with relevant consequences for the hazard assessment of an area inhabited by some 0.5 million people. The present-day margin is stretched over 100 km between the Volsci Range (VR) and the Pontian escarpment, being defined by moderate shallow seismicity (Mw≤4.6), relative high geothermal gradient and ongoing hydrothermal activity. Although major central volcanoes (e.g., Colli Albani), occurring at major fault intersections are well studied, smaller volcanic fields were so far unconstrained. Both field survey in the VR and offshore high-resolution geophysical data, allow us to: 1) better define the anatomy of the poorly known VR volcanic field; 2) furnish new insights on the regional Quaternary dynamics; 3) propose modes and reason of magma emplacement. The VR is composed of about 40 punctual and linear monogenic and mostly phreatomagmatic vents occurring at the edges of the Apennine carbonate fold-and-thrust belt and within the VR backbone. Volcanites are characterized by zeolitized to incoherent tuffs and surge deposits locally covered by lavas and slope deposits. Most explosive units host carbonate-rich lithics with different degrees of rounding and decarbonation, which frequently belong to Albian-Cenomanian aquifers. By comparing cross-section with lithic analyses we demonstrate that fragmentation, transport, progressive disintegration and decarbonation occur at multiple depths, depending on the fold-and-thrust belt setting. Thus, along the same vent zone, juvenile lithic composition proves repeated fragmentation within pressured-aquifers, testifying for fissural activity with implications for local seismic and volcanic assessment. Pyroclastic deposits occur as well in the Pontina and Fondi coastal plains at shallow depth suggesting recent (<10 kyr) and possibly local eruptions. Offshore, 25 km north of Ventotene, a middle Pleistocene 200 m-high truncated volcano was found partially covered by middle to recent deposits. It is delimited by well defined WNW-striking fault-controlled escarpment dissected by NE-striking faults. As on the Ponza-Zannone high, volcanic complex occur on a horst intersecting the two main regional trends, possibly associated with younger SE-stretching. Quaternary stretching rotation occurs as a response to Tyrrhenian back-arc opening and contemporaneous inarching of the Apennine front. In this frame, frontal to lateral slab tearing and retreat is tracked by E-rejuvenated volcanic activity along the Palmarola-Vesuvius lineament. In conclusion, we argue about the role NE-dipping crustal detachment(s) may have played into crustal thinning, driving and occasionally hampering magma-emplacement.

Potential for deserts to supply reliable renewable electric power

NASA Astrophysics Data System (ADS)

Labordena, Mercè; Lilliestam, Johan

2015-04-01

To avoid dangerous climate change, the electricity systems must be decarbonized by mid-century. The world has sufficient renewable electricity resources for complete power sector decarbonization, but an expansion of renewables poses several challenges for the electricity systems. First, wind and solar PV power are intermittent and supply-controlled, making it difficult to securely integrate this fluctuating generation into the power systems. Consequently, power sources that are both renewable and dispatchable, such as biomass, hydro and concentrating solar power (CSP), are particularly important. Second, renewable power has a low power density and needs vast areas of land, which is problematic both due to cost reasons and due to land-use conflicts, in particular with agriculture. Renewable and dispatchable technologies that can be built in sparsely inhabited regions or on land with low competition with agriculture would therefore be especially valuable; this land-use competition greatly limits the potential for hydro and biomass electricity. Deserts, however, are precisely such low-competition land, and are at the same time the most suited places for CSP generation, but this option would necessitate long transmission lines from remote places in the deserts to the demand centers such as big cities. We therefore study the potential for fleets of CSP plants in the large deserts of the world to produce reliable and reasonable-cost renewable electricity for regions with high and/or rapidly increasing electricity demand and with a desert within or close to its borders. The regions in focus here are the European Union, North Africa and the Middle East, China and Australia. We conduct the analysis in three steps. First, we identify the best solar generation areas in the selected deserts using geographic information systems (GIS), and applying restrictions to minimize impact on biodiversity, soils, human heath, and land-use and land-cover change. Second, we identify transmission corridors from the generation areas to the demand centers in the target regions, using a GIS-based transmission algorithm that minimizes economic, social and environmental costs. Third, we use the multi-scale energy system model Calliope to specify the optimal configuration and operation of the CSP fleet to reliably follow the demand every hour of the year in the target regions, and to calculate the levelized cost of doing so, including both generation and transmission costs. The final output will show whether and how much reliable renewable electricity can be supplied from CSP fleets in deserts to demand centers in adjacent regions, at which costs this is possible, as well as a detailed description of the routes of HVDC transmission links. We expect to find that the potential for deserts to supply reliable CSP to the regions in focus is very large in all cases, despite the long distances.

[Synthesis and characteristics of porous hydroxyapatite bioceramics].

PubMed

Niu, Jinlong; Zhang, Zhenxi; Jiang, Dazong

2002-06-01

The macroporous structure of human bone allows the ingrowth of the soft tissues and organic cells into the bone matrix, profits the development and metabolism of bone tissue, and adapts the bone to the change of load. There is great requirement for artificial biomimic porous bioactive ceramics with the similar structure of bone tissue that can be used clinically for repairing lost bone. Fine hydroxyapatite (HAp) powder produced by wet chemical reaction was mixed with hydrogen peroxide (H2O2), polyvinyl alcohol, methyl cellulose or other pores-making materials to form green cake. After drying at low temperature (below 100 degrees C) and decarbonizing at about 300 degrees C-400 degrees C, the spongy ceramic block was sintered at high temperature, thus, macroporous HAp bioceramic with interconnected pores and reasonable porosity and pore-diameter was manufactured. This kind of porous HAp bioceramics were intrinsically osteoinductive to a certain degree, but its outstanding property was that they can absorb human bone morphogenetic proteins and other bone growth factors to form composites, so that the macroporous HAp bioactive ceramic has appropriate feasibility for clinical application. From the point of biomedical application, the recent developments in synthesis and characteristics investigation of macroporous HAp are reviewed in this paper.

Evidence for a spike in mantle carbon outgassing during the Ediacaran period

NASA Astrophysics Data System (ADS)

Paulsen, Timothy; Deering, Chad; Sliwinski, Jakub; Bachmann, Olivier; Guillong, Marcel

2017-12-01

Long-term cycles in Earth's climate are thought to be primarily controlled by changes in atmospheric CO2 concentrations. Changes in carbon emissions from volcanic activity can create an imbalance in the carbon cycle. Large-scale changes in volcanic activity have been inferred from proxies such as the age abundance of detrital zircons, but the magnitude of carbon emissions depends on the style of volcanism as well as the amount. Here we analyse U-Pb age and trace element data of detrital zircons from Antarctica and compare the results with the global rock record. We identify a spike in CO2-rich carbonatite and alkaline magmatism during the Ediacaran period. Before the Ediacaran, secular cooling of the mantle and the advent of cooler subduction regimes promoted the sequestration of carbon derived from decarbonation of subducting oceanic slabs in the mantle. We infer that subsequent magmatism led to the extensive release of carbon that may at least in part be recorded in the Shuram-Wonoka carbon isotope excursion. We therefore suggest that this pulse of alkaline volcanism reflects a profound reorganization of the Neoproterozoic deep and surface carbon cycles and promoted planetary warming before the Cambrian radiation.

Novel pathways for fuels and lubricants from biomass optimized using life-cycle greenhouse gas assessment

DOE PAGES

Balakrishnan, Madhesan; Sacia, Eric R.; Sreekumar, Sanil; ...

2015-06-08

Decarbonizing the transportation sector is critical to achieving global climate change mitigation. Although biofuels will play an important role in conventional gasoline and diesel applications, bioderived solutions are particularly important in jet fuels and lubricants, for which no other viable renewable alternatives exist. Producing compounds for jet fuel and lubricant base oil applications often requires upgrading fermentation products, such as alcohols and ketones, to reach the appropriate molecular-weight range. Ketones possess both electrophilic and nucleophilic functionality, which allows them to be used as building blocks similar to alkenes and aromatics in a petroleum refining complex. Here, we develop a methodmore » for selectively upgrading biomass-derived alkyl methyl ketones with >95% yields into trimer condensates, which can then be hydrodeoxygenated in near-quantitative yields to give a new class of cycloalkane compounds. The basic chemistry developed here can be tailored for aviation fuels as well as lubricants by changing the production strategy. We demonstrate that a sugarcane biorefinery could use natural synergies between various routes to produce a mixture of lubricant base oils and jet fuels that achieve net life-cycle greenhouse gas savings of up to 80%.« less

Thermal and structural characterization of synthetic and natural nanocrystalline hydroxyapatite.

PubMed

Sofronia, Ancuta M; Baies, Radu; Anghel, Elena M; Marinescu, Cornelia A; Tanasescu, Speranta

2014-10-01

The aim of this work was to study the thermal stability on heating and to obtain the processing parameters of synthetic and bone-derived hydroxyapatite over temperatures between room temperature and 1400°C by thermal analysis (thermogravimetry (TG)/differential scanning calorimetry (DSC) and thermo-mechanical analysis-TMA). Structural and surface modifications related to samples origin and calcination temperature were investigated by Fourier transformed infrared (FTIR) and Raman spectroscopy, X-ray diffraction (XRD) and BET method. FTIR spectra indicated that the organic constituents and carbonate are no longer present in the natural sample calcined at 800°C. Raman spectra highlighted the decomposition products of the hydroxyapatite. The calcination treatment modifies the processes kinetics of the synthetic samples, being able to isolate lattice water desorption processes of decarbonization and the dehydroxylation processes. Shrinkage of calcined synthetic sample increases by 10% compared to uncalcined synthetic powder. From the TMA correlated with TG analysis and heat capacity data it can be concluded that sintering temperature of the synthetic samples should be chosen in the temperature range of the onset of dehydroxylation and the temperature at which oxyapatite decomposition begins. Copyright © 2014 Elsevier B.V. All rights reserved.

Novel pathways for fuels and lubricants from biomass optimized using life-cycle greenhouse gas assessment

PubMed Central

Balakrishnan, Madhesan; Sacia, Eric R.; Sreekumar, Sanil; Gunbas, Gorkem; Gokhale, Amit A.; Scown, Corinne D.; Toste, F. Dean; Bell, Alexis T.

2015-01-01

Decarbonizing the transportation sector is critical to achieving global climate change mitigation. Although biofuels will play an important role in conventional gasoline and diesel applications, bioderived solutions are particularly important in jet fuels and lubricants, for which no other viable renewable alternatives exist. Producing compounds for jet fuel and lubricant base oil applications often requires upgrading fermentation products, such as alcohols and ketones, to reach the appropriate molecular-weight range. Ketones possess both electrophilic and nucleophilic functionality, which allows them to be used as building blocks similar to alkenes and aromatics in a petroleum refining complex. Here, we develop a method for selectively upgrading biomass-derived alkyl methyl ketones with >95% yields into trimer condensates, which can then be hydrodeoxygenated in near-quantitative yields to give a new class of cycloalkane compounds. The basic chemistry developed here can be tailored for aviation fuels as well as lubricants by changing the production strategy. We also demonstrate that a sugarcane biorefinery could use natural synergies between various routes to produce a mixture of lubricant base oils and jet fuels that achieve net life-cycle greenhouse gas savings of up to 80%. PMID:26056307

Global and regional drivers of accelerating CO2 emissions

PubMed Central

Raupach, Michael R.; Marland, Gregg; Ciais, Philippe; Le Quéré, Corinne; Canadell, Josep G.; Klepper, Gernot; Field, Christopher B.

2007-01-01

CO2 emissions from fossil-fuel burning and industrial processes have been accelerating at a global scale, with their growth rate increasing from 1.1% y−1 for 1990–1999 to >3% y−1 for 2000–2004. The emissions growth rate since 2000 was greater than for the most fossil-fuel intensive of the Intergovernmental Panel on Climate Change emissions scenarios developed in the late 1990s. Global emissions growth since 2000 was driven by a cessation or reversal of earlier declining trends in the energy intensity of gross domestic product (GDP) (energy/GDP) and the carbon intensity of energy (emissions/energy), coupled with continuing increases in population and per-capita GDP. Nearly constant or slightly increasing trends in the carbon intensity of energy have been recently observed in both developed and developing regions. No region is decarbonizing its energy supply. The growth rate in emissions is strongest in rapidly developing economies, particularly China. Together, the developing and least-developed economies (forming 80% of the world's population) accounted for 73% of global emissions growth in 2004 but only 41% of global emissions and only 23% of global cumulative emissions since the mid-18th century. The results have implications for global equity. PMID:17519334

Emerging Methane Sources: A Bang or Whimper? (Invited)

NASA Astrophysics Data System (ADS)

Harriss, R. C.

2013-12-01

In this presentation we examine two emerging methane emission sources that may further accelerate climate change in the 21st century: 1) Will fugitive methane emissions associated with the development of unconventional natural gas resources pose a significant threat of accelerating climate change? 2) Will continued warming of Arctic regions destabilize permafrost and methane hydrates rapidly increasing global atmospheric methane that results in a catastrophic climate change emergency? These risks are currently described in two different guises, with unconventional gas as persistent and gradually unfolding threat and Arctic rapid warming and release of methane as a low-probability event that could in an instant change everything. Current research is far from answering the question of whether these emerging methane sources will lead to a climate change bang or whimper. Both issues reflect the need to understand complex environmental and engineered systems as they interact with social and economic forces. While the evolution of energy systems favors methane as a contemporary transition fuel, researchers and practitioners need to address the fugitive methane leakage, reliability, and safety of natural gas systems. The concept of a methane bridge as a viable direction to decarbonization is appealing; it's just not as big or fast a step as many scientists want.

Stability of iron-bearing carbonates in the deep Earth’s interior

DOE PAGES

Cerantola, Valerio; Bykova, Elena; Kupenko, Ilya; ...

2017-07-19

The presence of carbonates in inclusions in diamonds coming from depths exceeding 670 km are obvious evidence that carbonates exist in the Earth’s lower mantle. However, their range of stability, crystal structures and the thermodynamic conditions of the decarbonation processes remain poorly constrained. We investigate the behaviour of pure iron carbonate at pressures over 100 GPa and temperatures over 2,500 K using single-crystal X-ray diffraction and Mossbauer spectroscopy in laser-heated diamond anvil cells. On heating to temperatures of the Earth’s geotherm at pressures to B 50 GPa FeCO 3 partially dissociates to form various iron oxides. Furthermore, at higher pressures FeCO 3 forms two new structures— tetrairon(III) orthocarbonate Femore » $$3+\\atop{4}$$C 3O 12 and diiron(II) diiron(III) tetracarbonate Fe$$2+\\atop{2}$$ Fe$$3+\\atop{2}$$C 4 O 13, both phases containing CO 4 tetrahedra. Fe 4 C 4 O 13 is stable at conditions along the entire geotherm to depths of at least 2,500 km, thus demonstrating that self-oxidation-reduction reactions can preserve carbonates in the Earth’s lower mantle.« less

The assessment of global thermo-energy performances of existing district heating systems optimized by harnessing renewable energy sources

NASA Astrophysics Data System (ADS)

Şoimoşan, Teodora M.; Danku, Gelu; Felseghi, Raluca A.

2017-12-01

Within the thermo-energy optimization process of an existing heating system, the increase of the system's energy efficiency and speeding-up the transition to green energy use are pursued. The concept of multi-energy district heating system, with high harnessing levels of the renewable energy sources (RES) in order to produce heat, is expected to be the key-element in the future urban energy infrastructure, due to the important role it can have in the strategies of optimizing and decarbonizing the existing district heating systems. The issues that arise are related to the efficient integration of different technologies of harnessing renewable energy sources in the energy mix and to the increase of the participation levels of RES, respectively. For the holistic modeling of the district heating system, the concept of the energy hub was used, where the synergy of different primary forms of entered energy provides the system a high degree energy security and flexibility in operation. The optimization of energy flows within the energy hub allows the optimization of the thermo-energy district system in order to approach the dual concept of smart city & smart energy.

Thermal behaviour of chrome shavings and of sludges recovered after digestion of tanned solid wastes with calcium hydroxide

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

Tahiri, S.; Albizane, A.; Messaoudi, A.

2007-07-01

The thermal behaviour of chrome shavings and of sludges recovered after digestion of tanned wastes with Ca(OH){sub 2} was studied. Ashes obtained after incineration of wastes at various temperatures were analysed by X-ray diffraction and EDX method. The main crystallized phases present in the ash obtained at 600 deg. C are Cr{sub 2}O{sub 3} and NaCl. The diffractograms revealed an increase in the intensities of the chromium oxide peaks and a very notable decrease of the amount of sodium chloride at 1100 deg. C. EDX analysis revealed a total disappearance of the chlorine peak at this temperature. Scanning electron micrographsmore » show that the waste lost its fibrous aspect when the temperature increases. Formation of aggregates was noted after 550 deg. C. Combustion of organic matters and decarbonation phenomenon are the main stages observed on GTA and DTA curves of sludges. These phenomena are, respectively, exothermic and endothermic. The diffractogram of sludges recorded at 550 deg. C, in the presence of a constant oxygen surplus, revealed the presence of CaCrO{sub 4} and CaCO{sub 3}.« less

Biojet fuels and emissions mitigation in aviation: An integrated assessment modeling analysis

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

Wise, Marshall; Muratori, Matteo; Kyle, Page

Although the aviation sector is a relatively small contributor to total greenhouse gas emissions, it is a fast-growing, fossil fuel-intensive transportation mode. Because aviation is a mode for which liquid fuels currently have no practical substitute, biofuels are gaining attention as a promising cleaner alternative. In this paper, we use the GCAM integrated assessment model to develop scenarios that explore the potential impact of biojet fuels for use in aviation in the context of broader climate change mitigation. We show that a carbon price would have a significant impact on the aviation sector. In the absence of alternatives to jetmore » fuel from petroleum, mitigation potential is limited and would be at the expense of aviation service demand growth. However, mitigation efforts through the increased use of biojet fuels show potential to reduce the carbon intensity of aviation, and may not have a significant impact on carbon mitigation and bioenergy use in the rest of the energy system. The potential of biofuel to decarbonize air transport is significantly enhanced when carbon dioxide capture and storage (CCS) is used in the conversion process to produce jet fuels from biomass feedstock.« less

Novel pathways for fuels and lubricants from biomass optimized using life-cycle greenhouse gas assessment.

PubMed

Balakrishnan, Madhesan; Sacia, Eric R; Sreekumar, Sanil; Gunbas, Gorkem; Gokhale, Amit A; Scown, Corinne D; Toste, F Dean; Bell, Alexis T

2015-06-23

Decarbonizing the transportation sector is critical to achieving global climate change mitigation. Although biofuels will play an important role in conventional gasoline and diesel applications, bioderived solutions are particularly important in jet fuels and lubricants, for which no other viable renewable alternatives exist. Producing compounds for jet fuel and lubricant base oil applications often requires upgrading fermentation products, such as alcohols and ketones, to reach the appropriate molecular-weight range. Ketones possess both electrophilic and nucleophilic functionality, which allows them to be used as building blocks similar to alkenes and aromatics in a petroleum refining complex. Here, we develop a method for selectively upgrading biomass-derived alkyl methyl ketones with >95% yields into trimer condensates, which can then be hydrodeoxygenated in near-quantitative yields to give a new class of cycloalkane compounds. The basic chemistry developed here can be tailored for aviation fuels as well as lubricants by changing the production strategy. We also demonstrate that a sugarcane biorefinery could use natural synergies between various routes to produce a mixture of lubricant base oils and jet fuels that achieve net life-cycle greenhouse gas savings of up to 80%.

Can Growth Be Green?

PubMed

Gough, Ian

2015-01-01

This short article, based on a presentation at the London School of Economics, criticizes the common opinion that "green growth" offers a relatively painless - some even say pain-free - transition path for capitalist economies. After a brief summary of the daunting arithmetic entailed in combining fast decarbonization with continuing growth, the article advances 3 propositions. First, market-based carbon mitigation programs, such as carbon trading, cannot be sufficient and must be coupled with other policy pillars that foster transformative investment and widespread regulation. Second, a political economy of climate policy needs to draw on the lessons of comparative social policy research, which emphasizes the role of international pressures, interests, institutions, and ideas. Taking these into account gives a more realistic perspective on climate policy making in today's neoliberal world. Third, more radical policies on both consumption and production are called for, to ensure that carbon mitigation is not pursued at the expense of equity and social welfare. These include policies to restrain high-carbon luxury consumption and a transition toward shorter paid working time. The conclusion is that a realistic program of green growth will be immensely difficult and entail radical political change. © SAGE Publications 2015.

China's transportation energy consumption and CO2 emissions from a global perspective

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

Yin, Xiang; Chen, Wenying; Eom, Jiyong

2015-07-01

ABSTRACT Rapidly growing energy demand from China's transportation sector in the last two decades have raised concerns over national energy security, local air pollution, and carbon dioxide (CO2) emissions, and there is broad consensus that China's transportation sector will continue to grow in the coming decades. This paper explores the future development of China's transportation sector in terms of service demands, final energy consumption, and CO2 emissions, and their interactions with global climate policy. This study develops a detailed China transportation energy model that is nested in an integrated assessment model—Global Change Assessment Model (GCAM)—to evaluate the long-term energy consumptionmore » and CO2 emissions of China's transportation sector from a global perspective. The analysis suggests that, without major policy intervention, future transportation energy consumption and CO2 emissions will continue to rapidly increase and the transportation sector will remain heavily reliant on fossil fuels. Although carbon price policies may significantly reduce the sector's energy consumption and CO2 emissions, the associated changes in service demands and modal split will be modest, particularly in the passenger transport sector. The analysis also suggests that it is more difficult to decarbonize the transportation sector than other sectors of the economy, primarily owing to its heavy reliance on petroleum products.« less

Climate-society feedbacks and the avoidance of dangerous climate change

NASA Astrophysics Data System (ADS)

Jarvis, A. J.; Leedal, D. T.; Hewitt, C. N.

2012-09-01

The growth in anthropogenic CO2 emissions experienced since the onset of the Industrial Revolution is the most important disturbance operating on the Earth's climate system. To avoid dangerous climate change, future greenhouse-gas emissions will have to deviate from business-as-usual trajectories. This implies that feedback links need to exist between climate change and societal actions. Here, we show that, consciously or otherwise, these feedbacks can be represented by linking global mean temperature change to the growth dynamics of CO2 emissions. We show that the global growth of new renewable sources of energy post-1990 represents a climate-society feedback of ~0.25%yr-1 per degree increase in global mean temperature. We also show that to fulfil the outcomes negotiated in Durban in 2011, society will have to become ~ 50 times more responsive to global mean temperature change than it has been since 1990. If global energy use continues to grow as it has done historically then this would result in amplification of the long-term endogenous rate of decarbonization from -0.6%yr-1 to ~-13%yr-1. It is apparent that modest levels of feedback sensitivity pay large dividends in avoiding climate change but that the marginal return on this effort diminishes rapidly as the required feedback strength increases.

Long-term shifts in life-cycle energy efficiency and carbon intensity.

PubMed

Yeh, Sonia; Mishra, Gouri Shankar; Morrison, Geoff; Teter, Jacob; Quiceno, Raul; Gillingham, Kenneth; Riera-Palou, Xavier

2013-03-19

The quantity of primary energy needed to support global human activity is in large part determined by how efficiently that energy is converted to a useful form. We estimate the system-level life-cycle energy efficiency (EF) and carbon intensity (CI) across primary resources for 2005-2100. Our results underscore that although technological improvements at each energy conversion process will improve technology efficiency and lead to important reductions in primary energy use, market mediated effects and structural shifts toward less efficient pathways and pathways with multiple stages of conversion will dampen these efficiency gains. System-level life-cycle efficiency may decrease as mitigation efforts intensify, since low-efficiency renewable systems with high output have much lower GHG emissions than some high-efficiency fossil fuel systems. Climate policies accelerate both improvements in EF and the adoption of renewable technologies, resulting in considerably lower primary energy demand and GHG emissions. Life-cycle EF and CI of useful energy provide a useful metric for understanding dynamics of implementing climate policies. The approaches developed here reiterate the necessity of a combination of policies that target efficiency and decarbonized energy technologies. We also examine life-cycle exergy efficiency (ExF) and find that nearly all of the qualitative results hold regardless of whether we use ExF or EF.

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.

Renal and metabolic effects of three months of decarbonated cola beverages in rats.

PubMed

Celec, Peter; Pálffy, Roland; Gardlík, Roman; Behuliak, Michal; Hodosy, Július; Jáni, Peter; Bozek, Peter; Sebeková, Katarína

2010-11-01

Epidemiological studies have shown an association between the intake of cola beverages and chronic kidney diseases. Experimental evidence for the negative effects of cola intake on kidneys is lacking. Male Wistar rats had ad libitum access to water (control group) or three different sugar-sweetened cola beverages for three months. Despite very high cola intake (daily cca 140 mL), no differences were found in body weight, kidney weight, glomerular morphology, oxidative and carbonyl stress or expression of selected marker genes in the renal cortex. Interestingly, all groups consuming cola beverages had lower blood glucose levels during an oral glucose tolerance test, suggesting improved insulin sensitivity. Despite hyperfiltration (5-6-fold increase in diuresis), cola beverages had no effect on assessed parameters of renal function, histology, gene expression or oxidative stress. Moreover, cola intake seems to increase creatinine clearance and to decrease plasma levels of urea. In our study increased insulin sensitivity and altered renal functional parameters were observed in rats receiving cola beverages for three months. Whether the findings are due to the short duration of the study or interspecies metabolic differences should be uncovered in further studies. Even more interesting might be the analysis of effects of cola intake in animal models of diabetes.

Experimental investigation of the stability of Fe-rich carbonates in the lower mantle

NASA Astrophysics Data System (ADS)

Boulard, E.; Menguy, N.; Auzende, A.; Benzerara, K.; Bureau, H.; Antonangeli, D.; Corgne, A.; Morard, G.; Siebert, J.; Perrillat, J.; Guyot, F. J.; Fiquet, G.

2011-12-01

Carbonates are the main C-bearing minerals that are transported deep in the Earth's mantle via subduction of the oceanic lithosphere [1]. The fate of carbonates at mantle conditions plays a key role in the deep carbon cycle. Decarbonation, melting or reduction of carbonates will affect the extent and the way carbon is recycled into the deep Earth. To clarify the fate of carbonates in the deep mantle, high-pressure high-temperature experiments were carried out up to 105 GPa and 2850 K on oxide assemblages of (Mg,Fe)O + CO2. The presence of Fe(II) in starting materials induces redox reactions from which Fe(II) is oxidized and a part of the carbon is reduced. This leads to an assemblage of magnetite, diamonds, and carbonates or, pressure depending, their newly discovered Fe(III)-bearing high-pressure polymorphs based on a silicate-like chemistry with tetrahedrally coordinated carbon [2]. Our results show the possibility for carbon to be recycled in the lowermost mantle and provide evidence of a possible coexistence of reduced and oxidized carbon at lower mantle conditions. [1] Sleep, N. H., and K. Zahnle (2001) J. Geophys. Res.-Planets 106(E1), 1373-1399. [2] Boulard et al. (2011) PNAS, 108, 5184-5187.

Desiliconization and decarburization behavior of molten Fe-C-Si(-S) alloy with CO2 and O2

NASA Astrophysics Data System (ADS)

Taguchi, Kenji; Ono-Nakazato, Hideki; Usui, Tateo; Marukawa, Katsukiyo

2003-12-01

One of the most important problems in the steelmaking process is an increase of the disposal slag mainly discharged from the dephosphorization process. In order to reduce the quantity of the disposal slag, the complete removal of silicon from molten pig iron is considered very effective before the dephosphorization in the pretreatment process. From this point of view, the desiliconization and the decarburization behavior of Fe-C-Si alloy with CO2 and O2 has been investigated in the present work. It is thermodynamically calculated that silicon should be oxidized in preference to carbon over 0.60 mass pct Si under the condition of sSiO2=a C=1 at 1573 K and is experimentally confirmed that silicon is only oxidized under the condition in actual. Even under the competitive region of desiliconizing and decarbonizing, under 0.60 mass pct Si, silicon is found to be oxidized down to about 0.1 mass pct Si in preference. The overall rate constants for the desiliconization and the decarburization are derived, and the value for the desiliconization is one order of magnitude larger than that for the decarburization. The influence of sulfur is also examined, and the retarding effect is not observed on the oxidation reactions.

Dynamic Analysis of the Temperature and the Concentration Profiles of an Industrial Rotary Kiln Used in Clinker Production.

PubMed

Rodrigues, Diulia C Q; Soares, Atílio P; Costa, Esly F; Costa, Andréa O S

2017-01-01

Cement is one of the most used building materials in the world. The process of cement production involves numerous and complex reactions that occur under different temperatures. Thus, there is great interest in the optimization of cement manufacturing. Clinker production is one of the main steps of cement production and it occurs inside the kiln. In this paper, the dry process of clinker production is analysed in a rotary kiln that operates in counter flow. The main phenomena involved in clinker production is as follows: free residual water evaporation of raw material, decomposition of magnesium carbonate, decarbonation, formation of C3A and C4AF, formation of dicalcium silicate, and formation of tricalcium silicate. The main objective of this study was to propose a mathematical model that realistically describes the temperature profile and the concentration of clinker components in a real rotary kiln. In addition, the influence of different speeds of inlet gas and solids in the system was analysed. The mathematical model is composed of partial differential equations. The model was implemented in Mathcad (available at CCA/UFES) and solved using industrial input data. The proposal model is satisfactory to describe the temperature and concentration profiles of a real rotary kiln.

Progress in thermal comfort research over the last twenty years.

PubMed

de Dear, R J; Akimoto, T; Arens, E A; Brager, G; Candido, C; Cheong, K W D; Li, B; Nishihara, N; Sekhar, S C; Tanabe, S; Toftum, J; Zhang, H; Zhu, Y

2013-12-01

Climate change and the urgency of decarbonizing the built environment are driving technological innovation in the way we deliver thermal comfort to occupants. These changes, in turn, seem to be setting the directions for contemporary thermal comfort research. This article presents a literature review of major changes, developments, and trends in the field of thermal comfort research over the last 20 years. One of the main paradigm shift was the fundamental conceptual reorientation that has taken place in thermal comfort thinking over the last 20 years; a shift away from the physically based determinism of Fanger's comfort model toward the mainstream and acceptance of the adaptive comfort model. Another noticeable shift has been from the undesirable toward the desirable qualities of air movement. Additionally, sophisticated models covering the physics and physiology of the human body were developed, driven by the continuous challenge to model thermal comfort at the same anatomical resolution and to combine these localized signals into a coherent, global thermal perception. Finally, the demand for ever increasing building energy efficiency is pushing technological innovation in the way we deliver comfortable indoor environments. These trends, in turn, continue setting the directions for contemporary thermal comfort research for the next decades. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Hydro-economic modeling of integrated solutions for the water-energy-land nexus in Africa

NASA Astrophysics Data System (ADS)

Parkinson, S.; Kahil, M.; Wada, Y.; Krey, V.; Byers, E.; Johnson, N. A.; Burek, P.; Satoh, Y.; Willaarts, B.; Langan, S.; Riahi, K.

2017-12-01

This study focused on the development of the Extended Continental-scale Hydro-economic Optimization model (ECHO) and its application to the analysis of long-term water, energy and land use pathways for Africa. The framework is important because it integrates multi-decadal decisions surrounding investments into new water infrastructure, electric power generation and irrigation technologies. The improved linkages in ECHO reveal synergies between water allocation strategies across sectors and the greenhouse gas emissions resulting from electricity supply. The African case study features a reduced-form transboundary river network and associated environmental flow constraints covering surface and groundwater withdrawals. Interactions between local water constraints and the continental-scale economy are captured in the model through the combination of regional electricity markets. Spatially-explicit analysis of land availability is used to restrict future reservoir expansion. The analysis demonstrates the massive investments required to ensure rapidly expanding water, energy and food demands in Africa aligned with human development objectives are met in a sustainable way. Modeled constraints on environmental flows in line with presumptive ecological guidelines trigger diffusion of energy-intensive water supply technologies in water-stressed regions, with implications for the cost and speed of the electricity sector decarbonization required to achieve climate targets.

The load shift potential of plug-in electric vehicles with different amounts of charging infrastructure

NASA Astrophysics Data System (ADS)

Gnann, Till; Klingler, Anna-Lena; Kühnbach, Matthias

2018-06-01

Plug-in electric vehicles are the currently favoured option to decarbonize the passenger car sector. However, a decarbonisation is only possible with electricity from renewable energies and plug-in electric vehicles might cause peak loads if they started to charge at the same time. Both these issues could be solved with coordinated load shifting (demand response). Previous studies analyzed this research question by focusing on private vehicles with domestic and work charging infrastructure. This study additionally includes the important early adopter group of commercial fleet vehicles and reflects the impact of domestic, commercial, work and public charging. For this purpose, two models are combined. In a comparison of three scenarios, we find that charging of commercial vehicles does not inflict evening load peaks in the same magnitude as purely domestic charging of private cars does. Also for private cars, charging at work occurs during the day and may reduce the necessity of load shifting while public charging plays a less important role in total charging demand as well as load shifting potential. Nonetheless, demand response reduces the system load by about 2.2 GW or 2.8% when domestic and work charging are considered compared to a scenario with only domestic charging.

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

Veysey, Jason; Octaviano, Claudia; Calvin, Katherine

Mexico’s climate policy sets ambitious national greenhouse gas (GHG) emission reduction targets—30% versus a business-as-usual baseline by 2020, 50% versus 2000 by 2050. However, these goals are at odds with recent energy and emission trends in the country. Both energy use and GHG emissions in Mexico have grown substantially over the last two decades. Here, we investigate how Mexico might reverse current trends and reach its mitigation targets by exploring results from energy system and economic models involved in the CLIMACAP-LAMP project. To meet Mexico’s emission reduction targets, all modeling groups agree that decarbonization of electricity is needed, along withmore » changes in the transport sector, either to more efficient vehicles or a combination of more efficient vehicles and lower carbon fuels. These measures reduce GHG emissions as well as emissions of other air pollutants. The models find different energy supply pathways, with some solutions based on renewable energy and others relying on biomass or fossil fuels with carbon capture and storage. The economy-wide costs of deep mitigation could range from 2% to 4% of GDP in 2030, and from 7% to 15% of GDP in 2050. Our results suggest that Mexico has some flexibility in designing deep mitigation strategies, and that technological options could allow Mexico to achieve its emission reduction targets, albeit at a cost to the country.« less

Nuclear energy: Between global electricity demand, worldwide decarbonisation imperativeness, and planetary environmental implications.

PubMed

Prăvălie, Remus; Bandoc, Georgeta

2018-03-01

For decades, nuclear energy has been considered an important option for ensuring global energy security, and it has recently started being promoted as a solution for climate change mitigation. However, nuclear power remains highly controversial due to its associated risks - nuclear accidents and problematic radioactive waste management. This review aims to assess the viability of global nuclear energy economically (energy-wise), climatically and environmentally. To this end, the nuclear sector's energy- and climate-related advantages were explored alongside the downsides that mainly relate to radioactive pollution. Economically, it was found that nuclear energy is still an important power source in many countries around the world. Climatically, nuclear power is a low-carbon technology and can therefore be a viable option for the decarbonization of the world's major economies over the following decades, if coupled with other large-scale strategies such as renewable energies. These benefits are however outweighed by the radioactive danger associated to nuclear power plants, either in the context of the nuclear accidents that have already occurred or in that of the large amounts of long-lived nuclear waste that have been growing for decades and that represent a significant environmental and societal threat. Copyright © 2017 Elsevier Ltd. All rights reserved.

Anthropocene Dialogues: Decoupling Economic Prosperity from Carbon Emissions

NASA Astrophysics Data System (ADS)

Tewksbury, J.; Kohm, K.

2017-12-01

Anthropocene magazine is a new science magazine produced by Future Earth. Its mission is to bring together the world's leading scientists, technologists, and creatives to explore on-the-ground stories of sustainability science in action. For AGU 2017, Anthropocene magazine will stage an "Anthropocene Dialogue" based on its July 2017 issue. Anthropocene Dialogues are panel discussions about the successes and challenges of transformative science-policy collaborations by leading science journalists, researchers, and practitioners. The focus of this dialogue is: What are the scientific and technological innovations that drive the decarbonization of economies—from plugging artificial intelligence into electrical grids to new experiments in solar geoengineering. Panelist include: Robert Jackson of the Global Carbon Project discussing the historic decoupling of carbon emissions from GDP, Oliver Morton of The Economist speaking on how geoengineering can be a key element of a decoupling process; Robinson Meyer of The Atlantic outlining a coal "retirement plan" based on supply side economics; Wayt Gibbs of Scientific American tackling the quintessential question, How much energy will the world need? and Mark Harris of IEEE Spectrum looking at new experiments in artificial intelligence that could pull fossil fuels out of electrical grids, factories, data centers, and transit systems. For more information on these stories, visit: anthropocenemagazine.org/in-print/. Free sample copies of the magazine will be available at the session.

Incorporating land-use requirements and environmental constraints in low-carbon electricity planning for California.

PubMed

Wu, Grace C; Torn, Margaret S; Williams, James H

2015-02-17

The land-use implications of deep decarbonization of the electricity sector (e.g., 80% below 1990 emissions) have not been well-characterized quantitatively or spatially. We assessed the operational-phase land-use requirements of different low-carbon scenarios for California in 2050 and found that most scenarios have comparable direct land footprints. While the per MWh footprint of renewable energy (RE) generation is initially higher, that of fossil and nuclear generation increases over time with continued fuel use. We built a spatially explicit model to understand the interactions between resource quality and environmental constraints in a high RE scenario (>70% of total generation). We found that there is sufficient land within California to meet the solar and geothermal targets, but areas with the highest quality wind and solar resources also tend to be those with high conservation value. Development of some land with lower conservation value results in lower average capacity factors, but also provides opportunity for colocation of different generation technologies, which could significantly improve land-use efficiency and reduce permitting, leasing, and transmission infrastructure costs. Basing siting decisions on environmentally-constrained long-term RE build-out requirements produces significantly different results, including better conservation outcomes, than implied by the current piecemeal approach to planning.

Energy in the Anthropocene

NASA Astrophysics Data System (ADS)

Davis, S. J.; Caldeira, K.; Cao, L.; Hoffert, M.

2012-12-01

Human interference in Earth's natural systems is fueled by ever-increasing consumption of fossil energy. The energy we consume has enabled exponential growth of human population and economic wealth by expanding access to basic goods and services such as food, medicine, light, sanitation and refrigeration, as well as more advanced technologies such as transport and communication. In turn, population growth and economic development drive demand for even more energy. By 2050, it is expected that global energy demand will double to more than 30 TW. Unfortunately, the modern energy system is largely dependent on fossil fuels, and the CO2 released by burning of these fuels is the primary cause of anthropogenic climate change. As human civilization has expanded, primary energy sources have become progressively less carbon intensive, transitioning from the use of unsustainably harvested biomass to coal, oil and then natural gas. However, tremendous growth in the quantity of energy energy consumption in the industrial era has caused rapid growth of CO2 emissions. Limiting these emissions to avoid the more severe impacts of climate change while also meeting future demand for energy will require continuing the process of decarbonization by making a planetary-scale transition to largely carbon-emission-free energy technologies. In 2004, Pacala and Socolow proposed that such a transition could be achieved by stabilizing emissions at then-current levels for 50 years and then decreasing emissions by 2% per year afterward. They divided the task of stabilization into "wedges" that would grow linearly from zero to 1 gigatonne of carbon emissions avoided per year (GtC/y; 1 Gt = 10^12 kg) over 50 years, and asserted that deploying 7 wedges offset the growth of emissions and put us on a trajectory to stabilize atmospheric CO2 concentration at 500 ppm if emissions decreased sharply in the second half of the 21st century. However, in light of the growth of emissions since 2004, new carbon-climate model simulations suggest that stabilizing current emissions for 50 years is no longer consistent with either an atmospheric CO2 concentration of 500 ppm nor global temperature increases below 2°C. Thus, if "solving the carbon-climate problem for the next 50 years" means meeting these climate targets, then solving the climate problem means not just stabilizing but substantially reducing CO2 emissions over the next 50 years, ultimately to near zero. And such large reductions in annual emissions will entail many more than 7 wedges. Depending on whether or not historical rates of decarbonization continue, a phase-out of emissions over 50 years would require between 19 and 31 wedges, beyond the wedges that may already be included in the baseline scenario. This level of mitigation will require affordable carbon-free energy systems to be deployed at the scale of tens of terawatts. Any hope for such fundamental transformation of the global energy system depends upon coordinated efforts to innovate, plan, and deploy new transportation and energy systems that can provide affordable energy at scale without emitting CO2 to the atmosphere. Lacking such efforts, the climate of the Anthropocene will come to resemble that of the Cretaceous.

Decarbonizing the international shipping industry: Solutions and policy recommendations.

PubMed

Wan, Zheng; El Makhloufi, Abdel; Chen, Yang; Tang, Jiayuan

2018-01-01

Ship-source greenhouse gas (GHG) emissions could increase by up to 250% by 2050 from their 2012 levels, owing to increasing global freight volumes. Binding international legal agreements to regulate GHGs, however, are lacking as technical solutions remain expensive, and crucial industrial support is absent. In 2003, the International Maritime Organization adopted Resolution A.963 (23) to regulate shipping CO 2 emissions via technical, operational, and market-based routes. However, progress has been slow and uncertain; there is no concrete emission reduction target or definitive action plan. Yet, a full-fledged roadmap may not even emerge until 2023. In this policy analysis, we revisit the progress of technical, operational, and market-based routes and the associated controversies. We argue that 1) a performance-based index, though good-intentioned, has loopholes affecting meaningful CO 2 emission reductions driven by technical advancements; 2) using slow steaming to cut energy consumption stands out among all operational solutions thanks to its immediate and obvious results, but with the already slow speed in practice, this single source has limited emission reduction potential; 3) without a technology-savvy shipping industry, a market-based approach is essentially needed to address the environmental impact. To give shipping a 50:50 chance for contributing fairly and proportionately to keep global warming below 2°C, deep emission reductions should occur soon. Copyright © 2017 Elsevier Ltd. All rights reserved.

Pathways to Mexico’s climate change mitigation targets: A multi-model analysis

DOE PAGES

Veysey, Jason; Octaviano, Claudia; Calvin, Katherine; ...

2015-04-25

Mexico’s climate policy sets ambitious national greenhouse gas (GHG) emission reduction targets—30% versus a business-as-usual baseline by 2020, 50% versus 2000 by 2050. However, these goals are at odds with recent energy and emission trends in the country. Both energy use and GHG emissions in Mexico have grown substantially over the last two decades. Here, we investigate how Mexico might reverse current trends and reach its mitigation targets by exploring results from energy system and economic models involved in the CLIMACAP-LAMP project. To meet Mexico’s emission reduction targets, all modeling groups agree that decarbonization of electricity is needed, along withmore » changes in the transport sector, either to more efficient vehicles or a combination of more efficient vehicles and lower carbon fuels. These measures reduce GHG emissions as well as emissions of other air pollutants. The models find different energy supply pathways, with some solutions based on renewable energy and others relying on biomass or fossil fuels with carbon capture and storage. The economy-wide costs of deep mitigation could range from 2% to 4% of GDP in 2030, and from 7% to 15% of GDP in 2050. Our results suggest that Mexico has some flexibility in designing deep mitigation strategies, and that technological options could allow Mexico to achieve its emission reduction targets, albeit at a cost to the country.« less

A sunny future: expert elicitation of China's solar photovoltaic technologies

NASA Astrophysics Data System (ADS)

Lam, Long T.; Branstetter, Lee; Azevedo, Inês L.

2018-03-01

China has emerged as the global manufacturing center for solar photovoltaic (PV) products. Chinese firms have entered all stages of the supply chain, producing most of the installed solar modules around the world. Meanwhile, production costs are at record lows. The decisions that Chinese solar producers make today will influence the path for the solar industry and its role towards de-carbonization of global energy systems in the years to come. However, to date, there have been no assessments of the future costs and efficiency of solar PV systems produced by the Chinese PV industry. We perform an expert elicitation to assess the technological and non-technological factors that led to the success of China’s silicon PV industry as well as likely future costs and performance. Experts evaluated key metrics such as efficiency, costs, and commercial viability of 17 silicon and non-silicon solar PV technologies by 2030. Silicon-based technologies will continue to be the mainstream product for large-scale electricity generation application in the near future, with module efficiency reaching as high as 23% and production cost as low as 0.24/W. The levelized cost of electricity for solar will be around 34/MWh, allowing solar PV to be competitive with traditional energy resources like coal. The industry’s future developments may be affected by overinvestment, overcapacity, and singular short-term focus.

New host for carbon in the deep Earth

PubMed Central

Boulard, Eglantine; Gloter, Alexandre; Corgne, Alexandre; Antonangeli, Daniele; Auzende, Anne-Line; Perrillat, Jean-Philippe; Guyot, François; Fiquet, Guillaume

2011-01-01

The global geochemical carbon cycle involves exchanges between the Earth’s interior and the surface. Carbon is recycled into the mantle via subduction mainly as carbonates and is released to the atmosphere via volcanism mostly as CO2. The stability of carbonates versus decarbonation and melting is therefore of great interest for understanding the global carbon cycle. For all these reasons, the thermodynamic properties and phase diagrams of these minerals are needed up to core mantle boundary conditions. However, the nature of C-bearing minerals at these conditions remains unclear. Here we show the existence of a new Mg-Fe carbon-bearing compound at depths greater than 1,800 km. Its structure, based on three-membered rings of corner-sharing (CO4)4- tetrahedra, is in close agreement with predictions by first principles quantum calculations [Oganov AR, et al. (2008) Novel high-pressure structures of MgCO3, CaCO3 and CO2 and their role in Earth’s lower mantle. Earth Planet Sci Lett 273:38–47]. This high-pressure polymorph of carbonates concentrates a large amount of Fe(III) as a result of intracrystalline reaction between Fe(II) and (CO3)2- groups schematically written as 4FeO + CO2 → 2Fe2O3 + C. This results in an assemblage of the new high-pressure phase, magnetite and nanodiamonds. PMID:21402927

Simulation of Flow Fluid in the BOF Steelmaking Process

NASA Astrophysics Data System (ADS)

Lv, Ming; Zhu, Rong; Guo, Ya-Guang; Wang, Yong-Wei

2013-12-01

The basic oxygen furnace (BOF) smelting process consists of different chemical reactions among oxygen, slag, and molten steel, which engenders a vigorous stirring process to promote slagging, dephosphorization, decarbonization, heating of molten steel, and homogenization of steel composition and temperature. Therefore, the oxygen flow rate, lance height, and slag thickness vary during the smelting process. This simulation demonstrated a three-dimensional mathematical model for a 100 t converter applying four-hole supersonic oxygen lance and simulated the effect of oxygen flow rate, lance height, and slag thickness on the flow of molten bath. It is found that as the oxygen flow rate increases, the impact area and depth increases, which increases the flow speed in the molten bath and decreases the area of dead zone. Low oxygen lance height benefits the increase of impact depth and accelerates the flow speed of liquid steel on the surface of the bath, while high oxygen lance height benefits the increase of impact area, thereafter enhances the uniform distribution of radial velocity in the molten steel and increases the flow velocity of molten steel at the bottom of furnace hearth. As the slag thickness increases, the diameter of impinging cavity on the slag and steel surface decreases. The radial velocity of liquid steel in the molten bath is well distributed when the jet flow impact on the slag layer increases.

Insights on beer volatile profile: Optimization of solid-phase microextraction procedure taking advantage of the comprehensive two-dimensional gas chromatography structured separation.

PubMed

Martins, Cátia; Brandão, Tiago; Almeida, Adelaide; Rocha, Sílvia M

2015-06-01

The aroma profile of beer is crucial for its quality and consumer acceptance, which is modu-lated by a network of variables. The main goal of this study was to optimize solid-phase microextraction experimental parameters (fiber coating, extraction temperature, and time), taking advantage of the comprehensive two-dimensional gas chromatography structured separation. As far as we know, it is the first time that this approach was used to the untargeted and comprehensive study of the beer volatile profile. Decarbonation is a critical sample preparation step, and two conditions were tested: static and under ultrasonic treatment, and the static condition was selected. Considering the conditions that promoted the highest extraction efficiency, the following parameters were selected: poly(dimethylsiloxane)/divinylbenzene fiber coating, at 40ºC, using 10 min of pre-equilibrium followed by 30 min of extraction. Around 700-800 compounds per sample were detected, corresponding to the beer volatile profile. An exploratory application was performed with commercial beers, using a set of 32 compounds with reported impact on beer aroma, in which different patterns can be observed through the structured chromatogram. In summary, the obtained results emphasize the potential of this methodology to allow an in-depth study of volatile molecular composition of beer. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Technical note: An inverse method to relate organic carbon reactivity to isotope composition from serial oxidation

NASA Astrophysics Data System (ADS)

Hemingway, Jordon D.; Rothman, Daniel H.; Rosengard, Sarah Z.; Galy, Valier V.

2017-11-01

Serial oxidation coupled with stable carbon and radiocarbon analysis of sequentially evolved CO2 is a promising method to characterize the relationship between organic carbon (OC) chemical composition, source, and residence time in the environment. However, observed decay profiles depend on experimental conditions and oxidation pathway. It is therefore necessary to properly assess serial oxidation kinetics before utilizing decay profiles as a measure of OC reactivity. We present a regularized inverse method to estimate the distribution of OC activation energy (E), a proxy for bond strength, using serial oxidation. Here, we apply this method to ramped temperature pyrolysis or oxidation (RPO) analysis but note that this approach is broadly applicable to any serial oxidation technique. RPO analysis directly compares thermal reactivity to isotope composition by determining the E range for OC decaying within each temperature interval over which CO2 is collected. By analyzing a decarbonated test sample at multiple masses and oven ramp rates, we show that OC decay during RPO analysis follows a superposition of parallel first-order kinetics and that resulting E distributions are independent of experimental conditions. We therefore propose the E distribution as a novel proxy to describe OC thermal reactivity and suggest that E vs. isotope relationships can provide new insight into the compositional controls on OC source and residence time.

Reaching a 1.5°C target: socio-technical challenges for a rapid transition to low-carbon electricity systems.

PubMed

Eyre, Nick; Darby, Sarah J; Grünewald, Philipp; McKenna, Eoghan; Ford, Rebecca

2018-05-13

A 1.5°C global average target implies that we should no longer focus on merely incremental emissions reductions from the electricity system, but rather on fundamentally re-envisaging a system that, sooner rather than later, becomes carbon free. Many low-carbon technologies are surpassing mainstream predictions for both uptake and cost reduction. Their deployment is beginning to be disruptive within established systems. 'Smart technologies' are being developed to address emerging challenges of system integration, but their rates of future deployment remain uncertain. We argue that transition towards a system that can fully displace carbon generation sources will require expanding the focus of our efforts beyond technical solutions. Recognizing that change has social and technical dimensions, and that these interact strongly, we set out a socio-technical review that covers electricity infrastructure, citizens, business models and governance. It describes some of the socio-technical challenges that need to be addressed for the successful transition of the existing electricity systems. We conclude that a socio-technical understanding of electricity system transitions offers new and better insights into the potential and challenges for rapid decarbonization.This article is part of the theme issue 'The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'. © 2018 The Author(s).

Dehydration of diasporite to corundite in nature and experiment

NASA Astrophysics Data System (ADS)

Feenstra, A.; Wunder, B.

2002-02-01

The diasporite-corundite rock transformation, which releases 6 8 wt% H2O in an average metabauxite, was studied experimentally. The results are compared with petrological observations on the island of Naxos (Greece), where the transformation occurred in metakarst bauxites during prograde regional metamorphism. Dehydration experiments were started with fine-grained natural diasporite embedded in marble. The samples were first annealed in the diaspore stability field, then slowly brought to the final pressure-temperature (P-T) conditions in the corundum field and kept there five to seven days. Overstepping the diaspore-corundum equilibrium by ˜30 °C at 8 kbar resulted in partial dehydration of diaspore. As with the corundum-in isograd on Naxos, the corundum grew preferentially along the bauxite-marble contact. Experiments at 17 40 kbar with T oversteps of 40 150 °C resulted in complete diaspore breakdown. A high-porosity zone containing corundum and silicates developed along the bauxite-marble boundary, resulting from the solid volume decreases associated with the diaspore-corundum and decarbonation reactions. In nature, the marble similarly behaved as a barrier for liberated fluid, as indicated by coarse corundum- chloritoid segregations along metabauxite rims. In the 30 40 kbar experiments, the porous contact zone acted as fluid pathway, allowing partial dissolution of metabauxite. This demonstrates pronounced Al, Fe, and Ti mobility at high P and T of 600 800 °C.

Promoting renewable energy and energy efficiency in Africa: a framework to evaluate employment generation and cost effectiveness

NASA Astrophysics Data System (ADS)

Cantore, Nicola; Nussbaumer, Patrick; Wei, Max; Kammen, Daniel M.

2017-03-01

The ongoing debate over the cost-effectiveness of renewable energy (RE) and energy efficiency (EE) deployment often hinges on the current cost of incumbent fossil-fuel technologies versus the long-term benefit of clean energy alternatives. This debate is often focused on mature or ‘industrialized’ economies and externalities such as job creation. In many ways, however, the situation in developing economies is at least as or even more interesting due to the generally faster current rate of economic growth and of infrastructure deployment. On the one hand, RE and EE could help decarbonize economies in developing countries, but on the other hand, higher upfront costs of RE and EE could hamper short-term growth. The methodology developed in this paper confirms the existence of this trade-off for some scenarios, yet at the same time provides considerable evidence about the positive impact of EE and RE from a job creation and employment perspective. By extending and adopting a methodology for Africa designed to calculate employment from electricity generation in the U.S., this study finds that energy savings and the conversion of the electricity supply mix to renewable energy generates employment compared to a reference scenario. It also concludes that the costs per additional job created tend to decrease with increasing levels of both EE adoption and RE shares.

The Implications of Deep Mitigation Pathways

NASA Astrophysics Data System (ADS)

Calvin, K. V.

2016-12-01

The 21st Conference of Parties to the UNFCCC agreement called for limiting climate change to "well below 2°C above pre-industrial levels and pursuing efforts to limit the temperature increase to 1.5°C." A climate target of 1.5°C places a stringent constraint on allowable emissions over the twenty-first century. Roegli et al. (2015) set that constraint at 200-415 GtCO2 between 2011 and 2100 for a likely chance of staying below 1.5°C in 2100. Limiting emissions to these levels requires that global emissions peak and decline over the coming decades, with net negative global emissions by mid-century. This level of decarbonization requires dramatic shifts in the energy and agricultural sectors, and comes at significant economic costs. This talk explores the effect of mitigating climate change to 1.5°C on the economy, energy system, and terrestrial system. We quantify the required deployment of various low carbon technologies, as well as the amount of existing capital that is abandoned in an effort to limit emissions. We show the shifts required in the terrestrial system, including its contribution to carbon sequestration through afforestation and bioenergy. Additionally, we show the implications of deep mitigation pathways on energy, food, and carbon prices. We contrast these results with a reference, no climate policy, world and a 2°C.

Carbon and oxygen isotope study of carbonates from highly shocked clasts of the polymict breccia of the Haughton Crater (Canada)

NASA Technical Reports Server (NTRS)

Agrinier, P.; Martinez, I.; Javoy, M.; Schaerer, U.

1992-01-01

It is known that the release of volatiles on impact is an important controlling factor in cratering processes in carbonate terranes and in the mobility of chemical elements. In order to assess the nature and the role of carbon- and oxygen-bearing volatiles during impact-induced metamorphism of sedimentary rocks, the C-13/C-12 and O-18/O-16 ratios and carbonate contents were determined for 30 shocked clasts from the Haughton Crater polymict breccia as well as for some unshocked carbonates from the sedimentary cover adjacent to the crater. Shock-induced CO2 loss during decarbonation of calcite is known to be a function of peak pressure and ambient partial pressure of the volatile species. In our clast samples, shocked from 20 to 60 GPa, we expect about 20 to 100 percent CO2 loss and preferential depletion in C-13 and O-18 in the residual carbonate. Rayleigh model (progressive loss of CO2) and batch model (single-step loss of CO2) curves for this depletion are shown. The magnitudes of the C-13 and O-18 depletions increase with the increase of the CO2 loss. In addition, the isotopic depletions should be correlated with an enrichment in CaO and MgO in the residual solid.

Fault lubrication during earthquakes.

PubMed

Di Toro, G; Han, R; Hirose, T; De Paola, N; Nielsen, S; Mizoguchi, K; Ferri, F; Cocco, M; Shimamoto, T

2011-03-24

The determination of rock friction at seismic slip rates (about 1 m s(-1)) is of paramount importance in earthquake mechanics, as fault friction controls the stress drop, the mechanical work and the frictional heat generated during slip. Given the difficulty in determining friction by seismological methods, elucidating constraints are derived from experimental studies. Here we review a large set of published and unpublished experiments (∼300) performed in rotary shear apparatus at slip rates of 0.1-2.6 m s(-1). The experiments indicate a significant decrease in friction (of up to one order of magnitude), which we term fault lubrication, both for cohesive (silicate-built, quartz-built and carbonate-built) rocks and non-cohesive rocks (clay-rich, anhydrite, gypsum and dolomite gouges) typical of crustal seismogenic sources. The available mechanical work and the associated temperature rise in the slipping zone trigger a number of physicochemical processes (gelification, decarbonation and dehydration reactions, melting and so on) whose products are responsible for fault lubrication. The similarity between (1) experimental and natural fault products and (2) mechanical work measures resulting from these laboratory experiments and seismological estimates suggests that it is reasonable to extrapolate experimental data to conditions typical of earthquake nucleation depths (7-15 km). It seems that faults are lubricated during earthquakes, irrespective of the fault rock composition and of the specific weakening mechanism involved.

Complementing carbon prices with technology policies to keep climate targets within reach

NASA Astrophysics Data System (ADS)

Bertram, Christoph; Luderer, Gunnar; Pietzcker, Robert C.; Schmid, Eva; Kriegler, Elmar; Edenhofer, Ottmar

2015-03-01

Economic theory suggests that comprehensive carbon pricing is most efficient to reach ambitious climate targets, and previous studies indicated that the carbon price required for limiting global mean warming to 2 °C is between US$16 and US$73 per tonne of CO2 in 2015 (ref. ). Yet, a global implementation of such high carbon prices is unlikely to be politically feasible in the short term. Instead, most climate policies enacted so far are technology policies or fragmented and moderate carbon pricing schemes. This paper shows that ambitious climate targets can be kept within reach until 2030 despite a sub-optimal policy mix. With a state-of-the-art energy-economy model we quantify the interactions and unique effects of three major policy components: (1) a carbon price starting at US$7 per tonne of CO2 in 2015 to incentivize economy-wide mitigation, flanked by (2) support for low-carbon energy technologies to pave the way for future decarbonization, and (3) a moratorium on new coal-fired power plants to limit stranded assets. We find that such a mix limits the efficiency losses compared with the optimal policy, and at the same time lowers distributional impacts. Therefore, we argue that this instrument mix might be a politically more feasible alternative to the optimal policy based on a comprehensive carbon price alone.

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

Eichman, Josh; Flores-Espino, Francisco

Flexible operation of electrolysis systems represents an opportunity to reduce the cost of hydrogen for a variety of end-uses while also supporting grid operations and thereby enabling greater renewable penetration. California is an ideal location to realize that value on account of growing renewable capacity and markets for hydrogen as a fuel cell electric vehicle (FCEV) fuel, refineries, and other end-uses. Shifting the production of hydrogen to avoid high cost electricity and participation in utility and system operator markets along with installing renewable generation to avoid utility charges and increase revenue from the Low Carbon Fuel Standard (LCFS) program canmore » result in around $2.5/kg (21%) reduction in the production and delivery cost of hydrogen from electrolysis. This reduction can be achieved without impacting the consumers of hydrogen. Additionally, future strategies for reducing hydrogen cost were explored and include lower cost of capital, participation in the Renewable Fuel Standard program, capital cost reduction, and increased LCFS value. Each must be achieved independently and could each contribute to further reductions. Using the assumptions in this study found a 29% reduction in cost if all future strategies are realized. Flexible hydrogen production can simultaneously improve the performance and decarbonize multiple energy sectors. The lessons learned from this study should be used to understand near-term cost drivers and to support longer-term research activities to further improve cost effectiveness of grid integrated electrolysis systems.« less

Changing Urban Carbon Metabolism over Time: Historical Trajectory and Future Pathway.

PubMed

Chen, Shaoqing; Chen, Bin

2017-07-05

Cities are expected to play a major role in carbon emissions mitigation. A key step in decoupling urban economy from carbon emissions is to understand the full impact of socioeconomic development on urban metabolism over time. Herein, we establish a system-based framework for modeling the variation of urban carbon metabolism through time by integrating a metabolic flow inventory, input-output model, and network analysis. Using Beijing as a case study, we track the historical trajectory of carbon flows embodied in urban final consumption over 1985-2012. We find that while the tendency of increase in direct carbon emission continues within this time frame, consumption-based carbon footprint might have peaked around 2010. Significant transitions in emission intensity and roles sectors play in transferring carbon over the period are important signs of decoupling urban development from carbonization. Our further analysis of driving factors reveals a strong competition between efficiency gains and consumption level rise, showing a cumulative contribution of -584% and 494% to total carbon footprint, respectively. Projection into a future pathway suggests there is still a great potential for carbon mitigation for the city, but a strong mitigation plan is required to achieve such decarbonization before 2030. By bridging temporal metabolic model and socioeconomic planning, this framework fills one of the main gaps between monitoring of urban metabolism and design of a low-carbon economy.

Effects of California's Climate Policy in Facilitating CCUS

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

Burton, Elizabeth

California is at the forefront of addressing the challenges involved in redesigning its energy infrastructure to meet 2050 GHG reduction goals, but CCUS commercialization lags in California as it does elsewhere. It is unclear why this is the case given the state’s forefront position in aggressive climate change policy. The intent of this paper is to examine the factors that may explain why CCUS has not advanced as rapidly as other GHG emissions mitigation technologies in California and identify ways by which CCUS commercialization may be advanced in the context of California’s future energy infrastructure. CCUS has application to reducemore » GHG emissions from the power, industrial and transportation sectors in the state. Efficiency, use of renewable energy or nuclear generation to replace fossil fuels, use of lower or no-net-carbon feedstocks (such as biomass), and use of CCUS on fossil fuel generation are the main options, but California has fewer options for making the deep cuts in CO 2 emissions within the electricity sector to meet 2050 goals. California is already the most efficient of all 50 states as measured by electricity use per capita, and, while further efficiency measures can reduce per capita consumption, increasing population is still driving electricity demand upwards. A 1976 law prevents building any new nuclear plants until a federal high-level nuclear waste repository is approved. Most all in-state electricity generation already comes from natural gas; although California does plan to eliminate electricity imports from out-of-state coal-fired generation. Thus, the two options with greatest potential to reduce in-state power sector CO 2 emissions are replacing fossil with renewable generation or employing CCUS on natural gas power plants. Although some scenarios call on California to transition its electricity sector to 100 percent renewables, it is unclear how practical this approach is given the intermittency of renewable generation, mismatches between peak generation times and demand times, and the rate of progress in developing technologies for large-scale power storage. Vehicles must be electrified or move to biofuels or zero-carbon fuels in order to decarbonize the transportation sector. These options transfer the carbon footprint of transportation to other sectors: the power sector in the case of electric vehicles and the industrial and agricultural sectors in the case of biofuels or zero-carbon fuels. Thus, the underlying presumption to achieve overall carbon reductions is that the electricity used by vehicles does not raise the carbon emissions of the power sector: biofuel feedstock growth, harvest, and processing uses low carbon energy or production of fuels from fossil feedstocks employs CCUS. This results in future transportation sector energy derived solely from renewables, biomass, or fossil fuel point sources utilizing CCUS. In the industrial sector, the largest contributors to GHG emissions are transportation fuel refineries and cement plants. Emissions from refineries come from on-site power generation and hydrogen plants; while fuel mixes can be changed to reduce the GHG emissions from processing and renewable sources can be used to generate power, total decarbonization requires use of CCUS. Similarly, for cement plants, power generation may use carbon-free feedstocks instead of fossil fuels, but CO 2 emissions associated with the manufacture of cement products must be dealt with through CCUS. Of course, another option for these facilities is the purchase of offsets to create a zero-emissions plant.« less

Earth's Deep Carbon Cycle Constrained by Partial Melting of Mantle Peridotite and Eclogite

NASA Astrophysics Data System (ADS)

Dasgupta, R.; Hirschmann, M. M.; Withers, A. C.

2006-05-01

The mass of carbon in the mantle is thought to exceed that in all Earth's other reservoirs combined1 and large fluxes of carbon are cycled into and out of the mantle via subduction and volcanic emission. Devolatilization is known to release water in the mantle wedge, but release of carbon could be delayed if the relevant decarbonation reactions or solidi of oceanic crust are not encountered along P-T path of subduction. Outgassing of CO2 from the mantle also has a critical influence on Earth's climate for time scales of 108-109 yr1. The residence time for carbon in the mantle is thought to exceed the age of the Earth1,2, but it could be significantly shorter owing to pervasive deep melting beneath oceanic ridges. The dominant influx of carbon is via carbonate in altered ocean-floor basalts, which survives decarbonation during subduction. Our experiments demonstrate that solidi of carbonated eclogite remain hotter than average subduction geotherms at least as deep as transition zone3, and thus significant subducted C is delivered to the deep Earth, rather than liberated in the shallow mantle by melting. Flux of CO2 into the mantle, assuming average estimate of carbon in altered ocean crust of 0.21 wt. % CO24, can amount to 0.15 × 1015 g/yr. In upwelling mantle, however, partial melting of carbonated eclogite releases calcio-dolomitic carbonatite melt at depths near ~400 km and metasomatically implants carbonate to surrounding peridotite. Thus, volcanic release of CO2 to basalt source regions is likely controlled by the solidus of carbonated peridotite. Our recent experiments with nominally anhydrous, carbonate-bearing garnet lherzolite indicate that the solidus of peridotite with a trace amount of CO2 is ~500 °C lower than that of volatile-free peridotite at 10 GPa5. In upwelling mantle the solidus of carbonated lherzolite is ~100-200 km shallower than that of eclogite+CO2, but beneath oceanic ridges, initial melting occurs as deep as 300-330 km. For peridotite with ~100-1000 ppm CO2, this initial melting yields 0.03-0.3% carbonatite melt. Extraction of such melts from the mantle above 300 km implies residence times of 1 to 4 Gyr for carbon and other highly incompatible elements in the convecting mantle. Such short residence times suggest that large fractions of mantle carbon must be recycled rather than primordial. Implied CO2 fluxes are 0.12-3.4 × 1015 g/yr, which matches or exceeds direct estimates for CO2 fluxes at ridges (0.04-0.66 × 1015 g/yr) 1,6. However, not all of this deep extracted CO2 may reach ridges; some may instead be implanted into oceanic lithosphere, providing a widespread source for metasomatic fluids that are highly enriched in incompatible elements. 1Sleep, N. H. and Zahnle, K. 2001, JGR 106, 1373-1399. 2Zhang, Y. and Zindler, A. 1993, EPSL 117, 331-345. 3Dasgupta, R. et al. 2004, EPSL 227, 73-85. 4Alt, J. C. and Teagle, D. A. H. 1999, GCA, 1527-1535. 5Dasgupta, R. and Hirschmann, M. M. in press, Nature. 6Javoy, M. and Pineau, F. 1991, EPSL 107, 598-611.

Effects of California's Climate Policy in Facilitating CCUS

DOE PAGES

Burton, Elizabeth

2014-12-31

California is at the forefront of addressing the challenges involved in redesigning its energy infrastructure to meet 2050 GHG reduction goals, but CCUS commercialization lags in California as it does elsewhere. It is unclear why this is the case given the state’s forefront position in aggressive climate change policy. The intent of this paper is to examine the factors that may explain why CCUS has not advanced as rapidly as other GHG emissions mitigation technologies in California and identify ways by which CCUS commercialization may be advanced in the context of California’s future energy infrastructure. CCUS has application to reducemore » GHG emissions from the power, industrial and transportation sectors in the state. Efficiency, use of renewable energy or nuclear generation to replace fossil fuels, use of lower or no-net-carbon feedstocks (such as biomass), and use of CCUS on fossil fuel generation are the main options, but California has fewer options for making the deep cuts in CO 2 emissions within the electricity sector to meet 2050 goals. California is already the most efficient of all 50 states as measured by electricity use per capita, and, while further efficiency measures can reduce per capita consumption, increasing population is still driving electricity demand upwards. A 1976 law prevents building any new nuclear plants until a federal high-level nuclear waste repository is approved. Most all in-state electricity generation already comes from natural gas; although California does plan to eliminate electricity imports from out-of-state coal-fired generation. Thus, the two options with greatest potential to reduce in-state power sector CO 2 emissions are replacing fossil with renewable generation or employing CCUS on natural gas power plants. Although some scenarios call on California to transition its electricity sector to 100 percent renewables, it is unclear how practical this approach is given the intermittency of renewable generation, mismatches between peak generation times and demand times, and the rate of progress in developing technologies for large-scale power storage. Vehicles must be electrified or move to biofuels or zero-carbon fuels in order to decarbonize the transportation sector. These options transfer the carbon footprint of transportation to other sectors: the power sector in the case of electric vehicles and the industrial and agricultural sectors in the case of biofuels or zero-carbon fuels. Thus, the underlying presumption to achieve overall carbon reductions is that the electricity used by vehicles does not raise the carbon emissions of the power sector: biofuel feedstock growth, harvest, and processing uses low carbon energy or production of fuels from fossil feedstocks employs CCUS. This results in future transportation sector energy derived solely from renewables, biomass, or fossil fuel point sources utilizing CCUS. In the industrial sector, the largest contributors to GHG emissions are transportation fuel refineries and cement plants. Emissions from refineries come from on-site power generation and hydrogen plants; while fuel mixes can be changed to reduce the GHG emissions from processing and renewable sources can be used to generate power, total decarbonization requires use of CCUS. Similarly, for cement plants, power generation may use carbon-free feedstocks instead of fossil fuels, but CO 2 emissions associated with the manufacture of cement products must be dealt with through CCUS. Of course, another option for these facilities is the purchase of offsets to create a zero-emissions plant.« less

Subduction Metamorphism of Ophicarbonates beyond the Stability of Antigorite: insights into Carbonate Dissolution vs. Decarbonation from the Almirez ultramafic massif (S. Spain)

NASA Astrophysics Data System (ADS)

Menzel, Manuel; Garrido, Carlos J.; López Sánchez Vizcaíno, Vicente; Marchesi, Claudio; Hidas, Károly

2017-04-01

Subduction zone processes play a key role in determining the time and length-scales of long-term element cycles like the deep carbon cycle. Recent improvements in thermodynamic modelling of fluid properties at high pressure and new experiments have underlined the importance of carbonate dissolution by subduction fluids from dehydration reactions for the transfer of carbon out of the subducting slab. However, natural case studies are scarce, in particular regarding the impact of fluids generated by serpentinite dehydration, which are considered as a major dissolution agent for carbon due to the high temperature of antigorite breakdown (about 650°C) and the potentially large volumes of hydrated peridotites occurring in the upper part of the subducting oceanic mantle lithosphere. Here we report the occurrence of meta-ophicarbonate lenses within prograde Chl-harzburgites in the Almirez ultramafic massif (Betic Cordillera, S. Spain). The presence of these lenses indicates that carbonate minerals were preserved beyond the stability conditions of antigorite and were not dissolved by deserpentinization fluids. The largest meta-ophicarbonate lens in the Almirez Chl-harzburgites measures 8 x 160 m and is composed of a high-grade assemblage of olivine, Ti-clinohumite, diopside, chlorite, dolomite, calcite and Cr-bearing magnetite with a granofelsic to banded appearance. In this assemblage we identified, for the first time in the Betic Cordillera, aragonite inclusions in olivine and diopside using coupled EBSD and chemical mapping. Calcite-dolomite thermometry and thermodynamic equilibrium modelling constrain the peak metamorphic conditions to 1.7 - 1.9 GPa and 680 °C at very low XCO2. These conditions compare well with P-T-estimates for the surrounding Chl-harzburgites. There is strong evidence that the protolith of the carbonate rocks within Chl-harzburgites was an ophicarbonate zone: bulk rock contents of Ni and Cr are similarly high in the carbonate rocks as in Atg-serpentinites and Chl-harzburgites of the Almirez massif, and their major element compositions plot on the CaCO3-antigorite mixing line. As the meta-ophicarbonates are enclosed within prograde Chl-harzburgites, they have experienced a high fluid flux triggered by the antigorite breakdown in surrounding serpentinites at about 660 °C, with a high potential to dissolve carbonates. However, these carbonate lenses retain high amounts of dolomite and calcite (40 - 45 vol%), and their phase assemblages and stable isotope compositions of carbonate (δ18O = 13-17 ‰ V-SMOW and δ13C = -0.5-1 ‰ V-PDB) do not indicate a major fluid-induced decarbonation. The survival of carbonate may be due to the fact that antigorite dehydration occurred at up to 50 - 70 °C lower temperatures in the presence of CaCO3 than in pure serpentinites. This could lead to the formation of a relatively impermeable shell of carbonate-bearing olivine-diopside fels around the meta-ophicarbonates prior to the main serpentinite dehydration, thus protecting the carbonate-richer assemblages from dissolution. The example of the meta-ophicarbonates at Almirez suggests that this mechanism may lead to recycling of substantial amounts of carbon into the deep mantle via subduction of carbonate-bearing serpentinites. Funding: We acknowledge funding from the People programme (Marie Curie Actions - ITN) of the European Union FP7 under REA Grant Agreement n°608001.

The loess-paleosol profile Datthausen, on the penultimate-glacial terrace of the upper Danube River: Luminescence dating and interpretation

NASA Astrophysics Data System (ADS)

Kadereit, Annette; Sauer, Daniela; Kühn, Peter; Herrmann, Ludger; Kösel, Michael; Miller, Christopher; Shinonaga, Taeko; Kreutzer, Sebastian; Starkovich, Britt

2015-04-01

The loess-paleosol profile Datthausen is situated on the penultimate-glacial (Würmian) terrace of the upper Danube River in southern Germany. The sequence of reworked, mostly sandy loess deposits exhibits brownish, loamy paleosols in its lower part and slightly de-carbonated and hydromorphic horizons in its upper part. The stratigraphic bisection is interpreted as the transition from the terrestrial Middle Pleniglacial (Middle Würmian) to the Upper Pleniglacial (Upper Würmian). This interpretation is supported by the observation that the upper two of the loamy paleosols show an olive tint and features of sediment reworking at the top (see Sauer et al. in this session). A similar stratigraphic pattern was observed in other central European loess-paleosol sections (Schönhals et al. 1964, E&G 15: 199-206) and was recently corroborated for, e.g., Nussloch on the Upper Rhine and Schwalbenberg II on the Middle Rhine (Antoine et al. 2009, QSR 28: 2955-2973; Schirmer 2012, E&G 61: 32-47). However, the chronometric position of the terrestrial Middle Pleniglacial to Upper Pleniglacial (MPG/UPG) transition is still under debate, as are the palaeoclimatic triggers controlling loess and soil formation. Valuable information hereon may be gained by matching the terrestrial chronologies with the marine and Greenland ice-core records. The chronometry of the Datthausen section is based on blue-light stimulated luminescence (BLSL) dating of small aliquots (ca. 200-500 grains) of quartz coarse grains (125-212 µm), using a single-aliquot regeneration (SAR) protocol (Murray & Wintle 2000, Rad. Meas. 32: 57-73) and a minimum-age model (Galbraith et al. 1999, Archaeometry 41: 339-364). Formation of the paleosols was likely promoted during the warmer Greenland Interstadials (GIS). Luminescence dating on samples taken from these paleosols determines the time of sediment deposition that preceded the soil formation in the respective sediment. We sampled two horizons below and three horizons above the MPG/UPG-boundary. A BLSL-age around ca. 37-35 ka for the lowermost sampled paleosol (6Bg5) suggests soil formation during a period matching GIS7 to GIS5. Therefore, the paleosol could conform to the Lohne Soil at Nussloch and Schwalbenberg II. A BLSL-age around ca. 29 ka for the uppermost MPG-palaeosol (5Bg4) may indicate soil formation during GIS4 or GIS3. Fragments of snail shells in the lowermost dated UPG-horizon (3Bw1) point to a reworked soil sediment. BLSL-dating yielded an age around ca. 26-27 ka. Therefore, at Datthausen the MPG/UPG transition appears to conform to the transition from marine/oxygen isotope stage (MIS/OIS) 3 to 2. De-carbonated horizon 2Bg1 (around ca. 23 ka) may possibly match GIS2. Hydromorphic horizon Cg2 (around ca. 22 ka) fits in a later period of the last glacial maximum (LGM). Correlations between the loess-paleosol sequence and ice-core records are challenging as the luminescence ages have uncertainties of ca. 10 % (1-sigma). Further, the sediments appear partially bleached and, partly affected by bio- or cryturbation. Overall, the chronometry fits to the field observations and the results of the pedological analyses, but the MPG/UPG transition appears to start slightly later than at Nussloch and Schwalbenberg II, where it precedes the MIS3/MIS2 boundary.

Experimental high strain-rate deformation products of carbonate-silicate rocks: Comparison with terrestrial impact materials

NASA Astrophysics Data System (ADS)

van der Bogert, C. H.; Schultz, P. H.; Spray, J. G.

2008-09-01

Introduction. The response of carbonate to impact processes has thus far been investigated using a combination of thermodynamic modelling, shock experiments, and impact experiments. Localized shear deformation was suggested to play an important role in the failure of carbonate during some shock experiments [1,2], and was invoked to explain significant degassing of carbonates during oblique impact experiments [3]. The results of the impact experiments are at odds with experiments [4] that show back-reaction of CO2 with CaO and MgO could significantly reduce CO2 degassing during impact events. We performed a frictional-welding experiment in order to investigate the effects of high strain-rate deformation on carbonate-silicate target materials, exclusive of shock deformation effects, and to investigate the differing results of other experiments. Samples and Techniques. A frictional melting experiment was performed using dolomitic marble and quartzite samples to simulate conditions during an impact into carbonate-silicate target rocks. The experiment followed the method of Spray (1995) [5]. The 1.5 cm3 samples were mounted onto separate steel cylinders with epoxy. Using a Blacks FWH-3 axial friction-welding rig, the samples were brought into contact at room temperature and under dry conditions with ~5 MPa applied pressure. Contact was maintained for two seconds at 750 rpm for a sustained strain-rate of 102 to 103 s-1. Results. Vapor or fine dust escaped from the interface during the experiment. Immediately after sample separation, the interfaces were incandescent. Once cooled, opaque white material adhered to both the quartzite and dolomitic marble samples. Quartzite sample. Material was injected into cracks that formed in the quartzite sample. Cooling and crystallization of the friction products resulted in the formation of submicron-sized minerals such as periclase and Ca- and Ca,Mg-silicates (Fig. 1) including merwinite and åkermanite. While periclase was observed as an individual mineral species, no pure lime was observed to be present. In the quartzite sample, CaO is present only as a component of the Ca- and Ca,Mg-silicates. In the fine-grained shear zone materials, however, elemental mapping and EMP analyses reveal an overall segregation of MgO and CaO [6], suggesting that CaO is mostly present in Casilicates and Ca,Mg-silicates with low MgO contents. Dolomitic marble sample. The dolomitic marble section exhibited thinner, shorter fractures than the quartzite sample. Mechanical twinning was induced by the deformation. The adhered friction products were very fine-grained material with larger, untwinned calcite (Fig. 2), and dendritic carbonates with a composition similar to huntite. Most of the secondary calcite had rounded margins, which suggested that they were molten during the experiment. The dendritic huntite-like carbonate, with a CO2 content higher than of these secondary carbonate grains (Fig. 3). However, calcite was the dominant secondary mineral. The finegrained portion of the shear zone material contained pervasive vesicles. The vesicles immediately adjacent to the secondary calcite grains were smaller than those adjacent to the dolomitic marble. This suggests that incorporation of CO2 near the calcite grains facilitated their growth. Discussion. The textures and compositions of the experimental products indicate that the dolomitic marble decarbonated in response to the high temperatures generated during experimental deformation. Simultaneously, the liberated CaO recombined with CO2 to form molten calcite in the shear zone. This effect, in part, is due to the lower decarbonation temperature for dolomite versus calcite [c.f., 7], which allows calcite to survive at higher temperatures than dolomite. In addition, the confining pressure during the experiment was high enough to allow calcite to be present as a liquid [c.f., 8]. Both the calcite and dendritic carbonate are likely products of back-reaction of CaO and MgO with CO2. However, both CaO and MgO were also incorporated into secondary silicates, which reduced the total amount available to back-react with CO2. It appears that all CaO released from the dolomitic marble formed secondary minerals (carbonates and silicates), because it is not present as pure CaO. The MgO released from the dolomitic marble primarily formed secondary silicates, periclase, and minor secondary carbonate. As a result, the secondary carbonates cannot be a sink for all the CO2 gas released from the dolomitic marble, unless a much higher proportion of the huntite-like phase was present. Thus, there was a net release of CO2 gas from the original dolomitic marble. A portion of this CO2 remained trapped in vesicles, but CO2 gas also escaped from the shear zone. This is consistent with compositional measurements of the shear zone that suggest a release of at least 5 wt% CO2 relative to the original dolomitic marble. Comparison with terrestrial craters. Many of the descriptions of deformation features in carbonates at terrestrial craters, such as mechanical twinning and bent fractures [9-11], are similar to those seen in our experimental products. Carbonates that survive impact seem to accommodate both shock and shear deformation primarily through mechanical fracturing and twinning. Impact melts at craters in carbonate-rich targets have been found to contain both silicic and carbonatitic melts [e.g., 12], with mineral phases that are indicative of high temperature reactions between carbonate and silicate rocks [e.g., 9]. Our experiments also showed these characteristics, however, the mineral phases produced were slightly different and we have not observed silicate glass in our experimental products. The segregation of MgO from CaO has been observed, for example, at Haughton [12] and Popigai [13], and was also seen in our experimental products [6]. Implications. The products of high strain-rate deformation experiments with carbonate-silicate rocks are similar in many aspects to impact products at terrestrial craters in mixed carbonate-silicate targets. The experiments show that decarbonation of carbonate targets and high temperature reactions between carbonate and silicates in the target rocks are not exclusive effects of shock deformation. Shear deformation alone can generate temperature and pressure conditions necessary to decarbonate dolomitic marble and generate calcitic melts. Thus, high strain-rate deformation is a potentially major contributor to the total impact-related energy deposited into the target, especially for oblique impacts. Shear deformation occuring during and after shock deformation could, in fact, enhance the release of CO2 as a gas, by creating pathways that allow gases to escape from target materials. Understanding the relative importance and interaction of each CO2 releasing or trapping mechanism is important for the determination of the environmental significance of impacts in targets containing carbonates. References. [1] Lange M. A. and Ahrens T. J. (1986) EPSL 77, 409-418. [2] Tyburczy J. A. and Ahrens T. J. (1986) JGR 91, 4730-4744. [3] Schultz P. H. (1996) GSA Abstracts, A384. [4] Agrinier P., et al. (2001) GCA 65, 2615-2632. [5] Spray J. G. (1995) Geology 23, 1119-1122. [6] van der Bogert C. H., et al. (2007) LPI Contribution No. 1360, 123-124. [7] Martinez I., et al. (1995) JGR 100, 15456-15476. [8] Ivanov B. A. and Deutsch A. (2002) Phys. Earth Planet. Int. 129, 131-143. [9] Martinez I., et al. (1994) EPSL 121, 559-574. [10] Redeker H.-J. and Stöffler D. (1988) Meteoritics 23, 185-196. [11] Skála R. and Jakes P. (1999). In Large Meteorite Impacts and Planetary Evolution II (eds. B. O. Dressler and V. L. Sharpton), pp. 205-214. [12] Osinski G. R. and Spray J. G. (2001) EPSL 194, 17-29. [13] Kenkmann T., et al. (1999) LPS XXX, Abstract #1561.

How a future energy world could look?

NASA Astrophysics Data System (ADS)

Ewert, M.

2012-10-01

The future energy system will change significantly within the next years as a result of the following Mega Trends: de-carbonization, urbanization, fast technology development, individualization, glocalization (globalization and localization) and changing demographics. Increasing fluctuating renewable production will change the role of non-renewable generation. Distributed energy from renewables and micro generation will change the direction of the energy flow in the electricity grids. Production will not follow demand but demand has to follow production. This future system is enabled by the fast technical development of information and communication technologies which will be present in the entire system. In this paper the results of a comprehensive analysis with different scenarios is summarized. Tools were used like the analysis of policy trends in the European countries, modelling of the European power grid, modelling of the European power markets and the analysis of technology developments with cost reduction potentials. With these tools the interaction of the main actors in the energy markets like conventional generation and renewable generation, grid transport, electricity storage including new storage options from E-Mobility, Power to Gas, Compressed Air Energy storage and demand side management were considered. The potential application of technologies and investments in new energy technologies were analyzed within existing frameworks and markets as well as new business models in new markets with different frameworks. In the paper the over all trend of this analysis is presented by describing a potential future energy world. This world represents only one of numerous options with comparable characteristics.

California-Specific Power-to-Hydrogen and Power-to-Gas Business Case Evaluation

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

Eichman, Joshua D.; Flores-Espino, Francisco

Flexible operation of electrolysis systems represents an opportunity to reduce the cost of hydrogen for a variety of end-uses while also supporting grid operations and thereby enabling greater renewable penetration. California is an ideal location to realize that value on account of growing renewable capacity and markets for hydrogen as a fuel cell electric vehicle (FCEV) fuel, refineries, and other end-uses. Shifting the production of hydrogen to avoid high cost electricity and participation in utility and system operator markets along with installing renewable generation to avoid utility charges and increase revenue from the Low Carbon Fuel Standard (LCFS) program canmore » result in around $2.5/kg (21%) reduction in the production and delivery cost of hydrogen from electrolysis. This reduction can be achieved without impacting the consumers of hydrogen. Additionally, future strategies for reducing hydrogen cost were explored and include lower cost of capital, participation in the Renewable Fuel Standard program, capital cost reduction, and increased LCFS value. Each must be achieved independently and could each contribute to further reductions. Using the assumptions in this study found a 29% reduction in cost if all future strategies are realized. Flexible hydrogen production can simultaneously improve the performance and decarbonize multiple energy sectors. The lessons learned from this study should be used to understand near-term cost drivers and to support longer-term research activities to further improve cost effectiveness of grid integrated electrolysis systems.« less

Comparing the Climate Agendas of the Parties to the UN Framework Convention on Climate Change

NASA Astrophysics Data System (ADS)

Stephenson, S. R.; Oculi, N.

2016-12-01

Effective mitigation of and adaptation to climate change requires multilateral coordination of numerous political and scientific activities and priorities. Since its inception in 1992, the UN Framework Convention on Climate Change (UNFCCC) has sought a comprehensive international response to the climate threat, culminating most recently in December 2015 at COP 21. The Paris Agreement was lauded as a landmark step toward global climate action as it represented a consensus of 196 countries to limit global warming to 2° C above pre-industrial levels with an additional stated goal to "pursue efforts" to limit the increase to 1.5° C. However, taken in a vacuum, the global Agreement masks important differences among its signatory countries in capabilities and priorities for tackling climate change, and obscures pathways for place-specific scientific research and intervention. Here we present a quantitative content analysis of official UNFCCC documents including COP transcripts, meeting agendas, and mitigation commitments outlined in pledged Intended Nationally Determined Contributions (INDC) to reveal areas of alignment and divergence among UNFCCC stakeholders. Textual cluster analysis illustrates the relative salience of key climate-related discourses (e.g. vulnerability; loss and damage; decarbonization; technology transfer) in the agendas of negotiating parties, and the degree to which the interests of some parties are over- or under-represented in the final "consensus" agreement. Understanding these disparities, and their potential to promote cooperation and/or disagreement among stakeholders, will be critical to scientists' efforts to develop equitable and sustainable long-term climate solutions.

Pathways to Decarbonization. Natural Gas and Renewable Energy. Lessons Learned from Energy System Stakeholders

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

Pless, Jacquelyn; Arent, Douglas J.; Logan, Jeffrey

2015-04-30

Ensuring the resilience, reliability, flexibility, and affordability of the U.S. electric grid is increasingly important as the country addresses climate change and an aging infrastructure. State and federal policy and actions by industry, non-profits, and others create a dynamic framework for achieving these goals. Three principle low-carbon generation technologies have formed the basis for multiple scenarios leading toward a low-carbon, resilient, and affordable power system. While there is no “silver bullet,” one avenue identified by key stakeholders is the opportunity to invest in natural gas (NG) and renewable resources, both of which offer abundant domestic resource bases and contribute tomore » energy independence, carbon mitigation, and economic growth. NG and renewable electricity (RE) have traditionally competed for market share in the power sector, but there is a growing experience base and awareness for their synergistic use (Cochran et al. 2014). Building upon these observations and previous work, the Joint Institute for Strategic Energy Analysis (JISEA), in collaboration with the Center for the New Energy Economy and the Gas Technology Institute, convened a series of workshops in 2014 to explore NG and RE synergies in the U.S. power sector. This report captures key insights from the workshop series, Synergies of Natural Gas and Renewable Energy: 360 Degrees of Opportunity, as well as supporting economic valuation analyses conducted by JISEA researchers that quantify the value proposition of investing in NG and RE together as complements.« less

Driving forces in energy-related CO2 emissions in south and east coastal China: commonality and variations

NASA Astrophysics Data System (ADS)

Gao, C.; Liu, Y.; Jin, J.; Wei, T.

2015-12-01

East and south coastal China contributes to respectively about 30% and 8% of CO2 emissions in China and the world, and therefore play a critical role in achieving the national goal of emission reduction to mitigate the global warming. It also serves as a benchmark for the less developed regions of China, in terms of achieving the developed world's human development standard under lower per capita emissions. We analyze the driving forces of emissions in this region and their provincial characteristics by applying the Logarithmic Mean Divisia Index method. Our findings show that emissions have been doubled during the period from 2000 to 2012, along with three and two folds increase in economy and energy consumption, respectively. This suggests a persistent lock between economic growth and emissions, even in this socioeconomically advanced region in China. Provincial difference in annual emission growth reveals three distinguished low-carbon developmental stages, owning mainly to the effectiveness of energy efficiency in reducing emission growth. This may explain why previous climate policies have aimed to reduce carbon intensity. These results indicate that targeted measures on enhancing energy efficiency in the short term and de-carbonization of both the economic and energy structure in the long term can lower the emission growth more effectively and efficiently. They also suggest that factor-driven emission reduction strategies and policies are needed in the geographically and socioeconomically similar regions.

A methodological approach to characterize the resilience of aquatic ecosystems with application to Lake Annecy, France

NASA Astrophysics Data System (ADS)

Pinault, J.-L.; Berthier, F.

2007-01-01

We propose a methodological approach to characterize the resilience of aquatic ecosystems with respect to the evolution of environmental parameters as well as their aptitude to adapt to forcings. This method that is applied to Lake Annecy, France, proceeds in three stages. First, according to the depth, variations of physicochemical parameters versus time are separated into three components related to (1) energy transfer through the surface of the lake, (2) the flow of rivers and springs that feed the lake, and (3) long-term evolution of the benthic zone as a consequence of mineral and organic matter loads. Second, dynamics of the lake are deduced by analyzing the physicochemical parameter components related to the three boundary conditions. Third, a stochastic process associated with the transfer models aims to characterize the resilience of the lakes according to forcings. For Lake Annecy, whose dynamics are representative of oligotrophic stratified lakes controlled by decarbonation processes where turnover and mixing occurring once a year in winter, the major consequence is the impoverishment of dissolved oxygen in deep water in autumn due to a temperature increase of the surface water in summer. The simulation raises relevant questions about whether a connection exists between physicochemical parameters and global warming, which should not induce harmful consequences on water quality and biodiversity in deep water. This methodological approach is general since it does not use any physical conceptual model to predict the hydrosystem behavior but uses directly observed data.

Impacts of nationally determined contributions on 2030 global greenhouse gas emissions: uncertainty analysis and distribution of emissions

NASA Astrophysics Data System (ADS)

Benveniste, Hélène; Boucher, Olivier; Guivarch, Céline; Le Treut, Hervé; Criqui, Patrick

2018-01-01

Nationally Determined Contributions (NDCs), submitted by Parties to the United Nations Framework Convention on Climate Change before and after the 21st Conference of Parties, summarize domestic objectives for greenhouse gas (GHG) emissions reductions for the 2025-2030 time horizon. In the absence, for now, of detailed guidelines for the format of NDCs, ancillary data are needed to interpret some NDCs and project GHG emissions in 2030. Here, we provide an analysis of uncertainty sources and their impacts on 2030 global GHG emissions based on the sole and full achievement of the NDCs. We estimate that NDCs project into 56.8-66.5 Gt CO2eq yr-1 emissions in 2030 (90% confidence interval), which is higher than previous estimates, and with a larger uncertainty range. Despite these uncertainties, NDCs robustly shift GHG emissions towards emerging and developing countries and reduce international inequalities in per capita GHG emissions. Finally, we stress that current NDCs imply larger emissions reduction rates after 2030 than during the 2010-2030 period if long-term temperature goals are to be fulfilled. Our results highlight four requirements for the forthcoming ‘climate regime’: a clearer framework regarding future NDCs’ design, an increasing participation of emerging and developing countries in the global mitigation effort, an ambitious update mechanism in order to avoid hardly feasible decarbonization rates after 2030 and an anticipation of steep decreases in global emissions after 2030.

Biomass enables the transition to a carbon-negative power system across western North America

NASA Astrophysics Data System (ADS)

Sanchez, Daniel L.; Nelson, James H.; Johnston, Josiah; Mileva, Ana; Kammen, Daniel M.

2015-03-01

Sustainable biomass can play a transformative role in the transition to a decarbonized economy, with potential applications in electricity, heat, chemicals and transportation fuels. Deploying bioenergy with carbon capture and sequestration (BECCS) results in a net reduction in atmospheric carbon. BECCS may be one of the few cost-effective carbon-negative opportunities available should anthropogenic climate change be worse than anticipated or emissions reductions in other sectors prove particularly difficult. Previous work, primarily using integrated assessment models, has identified the critical role of BECCS in long-term (pre- or post-2100 time frames) climate change mitigation, but has not investigated the role of BECCS in power systems in detail, or in aggressive time frames, even though commercial-scale facilities are starting to be deployed in the transportation sector. Here, we explore the economic and deployment implications for BECCS in the electricity system of western North America under aggressive (pre-2050) time frames and carbon emissions limitations, with rich technology representation and physical constraints. We show that BECCS, combined with aggressive renewable deployment and fossil-fuel emission reductions, can enable a carbon-negative power system in western North America by 2050 with up to 145% emissions reduction from 1990 levels. In most scenarios, the offsets produced by BECCS are found to be more valuable to the power system than the electricity it provides. Advanced biomass power generation employs similar system design to advanced coal technology, enabling a transition strategy to low-carbon energy.

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

Motyka, R.J.; Hawkins, D.B.; Poreda, R.J.

Two compositionally different groups of mud volcanoes exist in the Copper River Basin: the Tolsona group which discharges Na-Ca rich, HCO/sub 3/-SO/sub 4/ poor saline waters accompanied by small amounts of gas, composed predominately of CH/sub 4/ and N/sub 2/; and the Klawasi group which discharges Ca poor, Na-HCO/sub 3/ rich saline waters accompanied by enormous amounts of CO/sub 2/. The Tolsona-type water chemistry and isotopic composition could have been produced through the following processes: dilution of original interstitial seawaters with paleo-meteoric waters, possibly during a period of uplift in the mid-Cretaceous; loss of HCO/sub 3/ and SO/sub 4/ andmore » modification of other constituent concentrations by shale-membrane filtration; further depletion of Mg, K, HCO/sub 3/, and SO/sub 4/, and enrichment in Ca and Sr through dolomitization, hydrolysis, and clay-forming processes; and leaching of B, I, Li, and SiO/sub 2/ from marine sediments. Compared to the Tolsona waters, the Klawasi waters are strongly enriched in Li, Na, K, Mg, HCO/sub 3/, SO/sub 4/, B, SiO/sub 2/ and delta/sup 18/O and strongly depleted in Ca, Sr and D. The Klawasi wates also contain high concentrations of arsenic (10 to 48 ppM). The differences in fluid chemistry between Klawasi and Tolsona can be explained as the result of the interaction of fluids derived from a magmatic intrusion and contact decarbonation of limestone beds underlying the Klawasi area with overlying Tolsona-type formation waters.« less

Large temporal scale and capacity subsurface bulk energy storage with CO2

NASA Astrophysics Data System (ADS)

Saar, M. O.; Fleming, M. R.; Adams, B. M.; Ogland-Hand, J.; Nelson, E. S.; Randolph, J.; Sioshansi, R.; Kuehn, T. H.; Buscheck, T. A.; Bielicki, J. M.

2017-12-01

Decarbonizing energy systems by increasing the penetration of variable renewable energy (VRE) technologies requires efficient and short- to long-term energy storage. Very large amounts of energy can be stored in the subsurface as heat and/or pressure energy in order to provide both short- and long-term (seasonal) storage, depending on the implementation. This energy storage approach can be quite efficient, especially where geothermal energy is naturally added to the system. Here, we present subsurface heat and/or pressure energy storage with supercritical carbon dioxide (CO2) and discuss the system's efficiency, deployment options, as well as its advantages and disadvantages, compared to several other energy storage options. CO2-based subsurface bulk energy storage has the potential to be particularly efficient and large-scale, both temporally (i.e., seasonal) and spatially. The latter refers to the amount of energy that can be stored underground, using CO2, at a geologically conducive location, potentially enabling storing excess power from a substantial portion of the power grid. The implication is that it would be possible to employ centralized energy storage for (a substantial part of) the power grid, where the geology enables CO2-based bulk subsurface energy storage, whereas the VRE technologies (solar, wind) are located on that same power grid, where (solar, wind) conditions are ideal. However, this may require reinforcing the power grid's transmission lines in certain parts of the grid to enable high-load power transmission from/to a few locations.

Is Planetary-Scale High Tech Civilization Climatically Sustainable?: The Geophysics v Economics Paradigm War

NASA Astrophysics Data System (ADS)

Hoffert, M.

2012-12-01

Climate/energy policy is gridlocked between (1) a geophysics perspective revealing long-term instabilities from continued energy consumption growth, of which the fossil fuel greenhouse an early symptom; and (2) short-term, fossil-fuel energized-rapid-economic-growth-driven policies likely adaptive for hunter-gatherers competing for scarce food, but climatically fatal to planetary-scale economies dependent on agriculture and "energy slaves." Incorporating social science into climate/energy policy formulation has focused on integrated assessment models (IAMs) exploring scenarios (parallel universes making different social choices) depicting the evolution of GDP, energy consumed, the energy technology mixture, land use, greenhouse gas and aerosol emissions, and radiative forcing). Representative concentration pathways (RCP) scenarios developed for the IPCC AR5 report imply 5-10 degree C warming from fossil fuel burning unless unprecedentedly fast decarbonization rates ~ 7 %/yr are implemented from 2020 to 2100. A massive transition to carbon neutrality by midcentury is needed to keep warming < 2 degrees C (FIG. 1).Fossil fuel greenhouse warming is leveraged by two orders of magnitude relative to heating from human energy consumption. Even if civilization successfully transitions to carbon-neutrality in time, but energy use continues growing at 2%/year, fossil-fuel-greenhouse level warming would be generated by heat rejecting in only 200-300 years underscoring that sustainability implies a steady state planetary economy (FIG.2). Evolutionary psychology and neuroeconomics are emergent disciplines that may illuminate the physical v social science paradigm conflict threatening human survivability.

Solidus of carbonated fertile peridotite under fluid-saturated conditions

NASA Astrophysics Data System (ADS)

Falloon, Trevor J.; Green, David H.

1990-03-01

The solidus for a fertile peridotite composition ("Hawaiian pyrolite") in the presence of a CO2-H2O fluid phase has been determined from 10 to 35 kbar. The intersection of the decarbonation reaction (olivine + diopside + CO2 ←→ orthopyroxene + dolomite) with the pyrolite solidus defines the point Q‧, located at 22 kbar and 940 °C. At pressures less than Q‧, the solidus passes through a temperature maximum at 14 kbar, 1060 °C. The solidus is coincident with amphibole breakdown at pressures less than 16 kbar. At pressures above Q‧, the solidus is defined by the dissolution of crystalline carbonate into a sodic, dolomitic carbonatite melt. The solidus is at a temperature of 925 °C at ˜28 kbar. The solidus temperature above the point Q‧ is similar to the solidus determined for Hawaiian pyrolite-H2O-CO2 for small contents of H2O (<0.3 wt%) and CO2 (<5 wt%), thus indicating that the primary sodic dolomitic carbonatite melt at both solidi has a very low and limited H2O solubility. The new data clarify the roles of carbonatite melt, carbonated silicate melt, and H2O-rich fluid in mantle conditions that are relatively oxidized (fO2 ˜ MW to FMQ). In particular, a carbonatite melt + garnet lherzolite region is intersected by continental shield geothermal gradients, but such geotherms only intersect regions with carbonated silicate melt if perturbed to higher temperatures ("kinked geotherm").

Oxygen and carbon isotope compositions of carbonates in a prominent lithologically mixed unit in the central South Norwegian Caledonides

NASA Astrophysics Data System (ADS)

Jakob, Johannes; Boulvais, Philippe; Andersen, Torgeir B.

2018-06-01

A prominent pre-Scandian lithologically mixed unit in the central South Norwegian Caledonides contains more than 100 partly carbonated and hydrated metaperidotite bodies and locally fossiliferous detrital serpentinites. The lateral consistency of this mixed unit was not fully appreciated in the past. Therefore, parts of the mixed unit along strike were interpreted to belong to several different tectonostratigraphic levels. Here, we present new carbonate stable isotope data that suggest that the carbonates of the mixed unit between Bergen and Otta (re-)equilibrated at unit-wide similar peak metamorphic conditions. The isotope compositions are characteristic for this unit and indicate that it represented one single tectonic unit during the Scandian Orogeny. The carbonates in the mélange are characterized by a narrow range of δ18O (SMOW) values between + 11 and + 15.5‰ and three groups of δ13C (PDB) values: (I) + 1.6 to + 0.3‰, (II) - 1.8 to - 3.9‰, and (III) - 6 to - 8.6‰. Carbonates of group III probably were affected by decarbonation or by a fluid containing organic carbon, whereas carbonates of group I and II overlap with δ13C values typical for Ediacaran-Silurian marine carbonates and may have retained their initial δ13C imprint. We suggest that the δ18O values (re-)equilibrated with unit-wide released metamorphic fluids during Scandian metamorphism. An outcrop-scale homogenisation of the δ13C values reflects the local carbon isotope signature of the released metamorphic fluids that circulated channelized through the mélange unit.

Defining climate change scenario characteristics with a phase space of cumulative primary energy and carbon intensity

NASA Astrophysics Data System (ADS)

Ritchie, Justin; Dowlatabadi, Hadi

2018-02-01

Climate change modeling relies on projections of future greenhouse gas emissions and other phenomena leading to changes in planetary radiative forcing. Scenarios of socio-technical development consistent with end-of-century forcing levels are commonly produced by integrated assessment models. However, outlooks for forcing from fossil energy combustion can also be presented and defined in terms of two essential components: total energy use this century and the carbon intensity of that energy. This formulation allows a phase space diagram to succinctly describe a broad range of possible outcomes for carbon emissions from the future energy system. In the following paper, we demonstrate this phase space method with the Representative Concentration Pathways (RCPs) as used in the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5). The resulting RCP phase space is applied to map IPCC Working Group III (WGIII) reference case ‘no policy’ scenarios. Once these scenarios are described as coordinates in the phase space, data mining techniques can readily distill their core features. Accordingly, we conduct a k-means cluster analysis to distinguish the shared outlooks of these scenarios for oil, gas and coal resource use. As a whole, the AR5 database depicts a transition toward re-carbonization, where a world without climate policy inevitably leads to an energy supply with increasing carbon intensity. This orientation runs counter to the experienced ‘dynamics as usual’ of gradual decarbonization, suggesting climate change targets outlined in the Paris Accord are more readily achievable than projected to date.

Oxygen and carbon isotope compositions of carbonates in a prominent lithologically mixed unit in the central South Norwegian Caledonides

NASA Astrophysics Data System (ADS)

Jakob, Johannes; Boulvais, Philippe; Andersen, Torgeir B.

2017-11-01

A prominent pre-Scandian lithologically mixed unit in the central South Norwegian Caledonides contains more than 100 partly carbonated and hydrated metaperidotite bodies and locally fossiliferous detrital serpentinites. The lateral consistency of this mixed unit was not fully appreciated in the past. Therefore, parts of the mixed unit along strike were interpreted to belong to several different tectonostratigraphic levels. Here, we present new carbonate stable isotope data that suggest that the carbonates of the mixed unit between Bergen and Otta (re-)equilibrated at unit-wide similar peak metamorphic conditions. The isotope compositions are characteristic for this unit and indicate that it represented one single tectonic unit during the Scandian Orogeny. The carbonates in the mélange are characterized by a narrow range of δ18O (SMOW) values between + 11 and + 15.5‰ and three groups of δ13C (PDB) values: (I) + 1.6 to + 0.3‰, (II) - 1.8 to - 3.9‰, and (III) - 6 to - 8.6‰. Carbonates of group III probably were affected by decarbonation or by a fluid containing organic carbon, whereas carbonates of group I and II overlap with δ13C values typical for Ediacaran-Silurian marine carbonates and may have retained their initial δ13C imprint. We suggest that the δ18O values (re-)equilibrated with unit-wide released metamorphic fluids during Scandian metamorphism. An outcrop-scale homogenisation of the δ13C values reflects the local carbon isotope signature of the released metamorphic fluids that circulated channelized through the mélange unit.

The contribution of transport policies to the mitigation potential and cost of 2 °C and 1.5 °C goals

NASA Astrophysics Data System (ADS)

Zhang, Runsen; Fujimori, Shinichiro; Hanaoka, Tatsuya

2018-05-01

The transport sector contributes around a quarter of global CO2 emissions; thus, low-carbon transport policies are required to achieve the 2 °C and 1.5 °C targets. In this paper, representative transport policy scenarios are structured with the aim of achieving a better understanding of the interaction between the transport sector and the macroeconomy. To accomplish this, the Asia–Pacific Integrated Model/Transport (AIM/Transport) model, coupled with a computable general equilibrium model (AIM/CGE), is used to simulate the potential for different transport policy interventions to reduce emissions and cost over the period 2005–2100. The results show that deep decarbonization in the transport sector can be achieved by implementing transport policies such as energy efficiency improvements, vehicle technology innovations particularly the deployment of electric vehicles, public transport developments, and increasing the car occupancy rate. Technological transformations such as vehicle technological innovations and energy efficiency improvements provide the most significant reduction potential. The key finding is that low-carbon transport policies can reduce the carbon price, gross domestic product loss rate, and welfare loss rate generated by climate mitigation policies to limit global warming to 2 °C and 1.5 °C. Interestingly, the contribution of transport policies is more effective for stringent climate change targets in the 1.5 °C scenario, which implies that the stronger the mitigation intensity, the more transport specific policy is required. The transport sector requires attention to achieve the goal of stringent climate change mitigation.

Challenges and opportunities for hydrogen production from microalgae.

PubMed

Oey, Melanie; Sawyer, Anne Linda; Ross, Ian Lawrence; Hankamer, Ben

2016-07-01

The global population is predicted to increase from ~7.3 billion to over 9 billion people by 2050. Together with rising economic growth, this is forecast to result in a 50% increase in fuel demand, which will have to be met while reducing carbon dioxide (CO2 ) emissions by 50-80% to maintain social, political, energy and climate security. This tension between rising fuel demand and the requirement for rapid global decarbonization highlights the need to fast-track the coordinated development and deployment of efficient cost-effective renewable technologies for the production of CO2 neutral energy. Currently, only 20% of global energy is provided as electricity, while 80% is provided as fuel. Hydrogen (H2 ) is the most advanced CO2 -free fuel and provides a 'common' energy currency as it can be produced via a range of renewable technologies, including photovoltaic (PV), wind, wave and biological systems such as microalgae, to power the next generation of H2 fuel cells. Microalgae production systems for carbon-based fuel (oil and ethanol) are now at the demonstration scale. This review focuses on evaluating the potential of microalgal technologies for the commercial production of solar-driven H2 from water. It summarizes key global technology drivers, the potential and theoretical limits of microalgal H2 production systems, emerging strategies to engineer next-generation systems and how these fit into an evolving H2 economy. © 2016 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

Reducing GHG emissions in the United States' transportation sector

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

Das, Sujit; Andress, David A; Nguyen, Tien

Reducing GHG emissions in the U.S. transportation sector requires both the use of highly efficient propulsion systems and low carbon fuels. This study compares reduction potentials that might be achieved in 2060 for several advanced options including biofuels, hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), and fuel cell electric vehicles (FCEV), assuming that technical and cost reduction targets are met and necessary fueling infrastructures are built. The study quantifies the extent of the reductions that can be achieved through increasing engine efficiency and transitioning to low-carbon fuels separately. Decarbonizing the fuels is essential for achieving large reductions inmore » GHG emissions, and the study quantifies the reductions that can be achieved over a range of fuel carbon intensities. Although renewables will play a vital role, some combination of coal gasification with carbon capture and sequestration, and/or nuclear energy will likely be needed to enable very large reductions in carbon intensities for hydrogen and electricity. Biomass supply constraints do not allow major carbon emission reductions from biofuels alone; the value of biomass is that it can be combined with other solutions to help achieve significant results. Compared with gasoline, natural gas provides 20% reduction in GHG emissions in internal combustion engines and up to 50% reduction when used as a feedstock for producing hydrogen or electricity, making it a good transition fuel for electric propulsion drive trains. The material in this paper can be useful information to many other countries, including developing countries because of a common factor: the difficulty of finding sustainable, low-carbon, cost-competitive substitutes for petroleum fuels.« less

A reduced-form approach for representing the impacts of wind and solar PV deployment on the structure and operation of the electricity system

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

Johnson, Nils; Strubegger, Manfred; McPherson, Madeleine

In many climate change mitigation scenarios, integrated assessment models of the energy and climate systems rely heavily on renewable energy technologies with variable and uncertain generation, such as wind and solar PV, to achieve substantial decarbonization of the electricity sector. However, these models often include very little temporal resolution and thus have difficulty in representing the integration costs that arise from mismatches between electricity supply and demand. The global integrated assessment model, MESSAGE, has been updated to explicitly model the trade-offs between variable renewable energy (VRE) deployment and its impacts on the electricity system, including the implications for electricity curtailment,more » backup capacity, and system flexibility. These impacts have been parameterized using a reduced-form approach, which allows VRE integration impacts to be quantified on a regional basis. In addition, thermoelectric technologies were updated to include two modes of operation, baseload and flexible, to better account for the cost, efficiency, and availability penalties associated with flexible operation. In this paper, the modeling approach used in MESSAGE is explained and the implications for VRE deployment in mitigation scenarios are assessed. Three important stylized facts associated with integrating high VRE shares are successfully reproduced by our modeling approach: (1) the significant reduction in the utilization of non-VRE power plants; (2) the diminishing role for traditional baseload generators, such as nuclear and coal, and the transition to more flexible technologies; and (3) the importance of electricity storage and hydrogen electrolysis in facilitating the deployment of VRE.« less

Coal-fired Power Plants with Flexible Amine-based CCS and Co-located Wind Power: Environmental, Economic and Reliability Outcomes

NASA Astrophysics Data System (ADS)

Bandyopadhyay, Rubenka

Carbon Capture and Storage (CCS) technologies provide a means to significantly reduce carbon emissions from the existing fleet of fossil-fired plants, and hence can facilitate a gradual transition from conventional to more sustainable sources of electric power. This is especially relevant for coal plants that have a CO2 emission rate that is roughly two times higher than that of natural gas plants. Of the different kinds of CCS technology available, post-combustion amine based CCS is the best developed and hence more suitable for retrofitting an existing coal plant. The high costs from operating CCS could be reduced by enabling flexible operation through amine storage or allowing partial capture of CO2 during high electricity prices. This flexibility is also found to improve the power plant's ramp capability, enabling it to offset the intermittency of renewable power sources. This thesis proposes a solution to problems associated with two promising technologies for decarbonizing the electric power system: the high costs of the energy penalty of CCS, and the intermittency and non-dispatchability of wind power. It explores the economic and technical feasibility of a hybrid system consisting of a coal plant retrofitted with a post-combustion-amine based CCS system equipped with the option to perform partial capture or amine storage, and a co-located wind farm. A techno-economic assessment of the performance of the hybrid system is carried out both from the perspective of the stakeholders (utility owners, investors, etc.) as well as that of the power system operator. (Abstract shortened by ProQuest.).

Towards the next generation of climate change assessment: learning from past experiences to inform a sustainable future

NASA Astrophysics Data System (ADS)

Mach, K. J.; Field, C. B.

2017-12-01

Over decades, assessment by the Intergovernmental Panel on Climate Change and many others has bolstered understanding of the climate problem: unequivocal warming, pervasive impacts, and serious risks from continued high emissions of heat-trapping gases. Societies are increasingly responding with early actions to decarbonize energy systems and prepare for impacts. This emerging era of climate solutions creates a need for new approaches to assessment that emphasize learning from ongoing real-world experiences and that help close the gap between aspirations and the pace of progress. Against this backdrop, the presentation will take stock of recent advances and challenges in assessment, especially drawing from analysis of climate change assessment. Four assessment priorities will be considered: (1) integrating diverse evidence including quantitative and qualitative results, (2) applying rigorous expert judgment in evaluating knowledge and uncertainties, (3) exploring widely ranging futures and their connections to ongoing choices and actions, and (4) incorporating interactions among experts and decision-makers in assessment processes. Across these assessment priorities, the presentation will critique both opportunities and pitfalls, outlining possibilities for future experimentation, innovation, and learning. It will evaluate, in particular, lessons from risk-based approaches; strategies for transparently acknowledging persistent uncertainties and contested priorities; ways to minimize biases and foster creativity in expert judgments; scenario-based assessment of surprises, deep uncertainties, and decision-making implications; and opportunities for broadening the conception of expertise and engaging different decision-makers and stakeholders. Overall, these approaches can advance assessment products and processes as a basis for sustained dialogue supporting decision-making.

Sources and fractionation processes influencing the isotopic distribution of H, O and C in the Long Valley hydrothermal system, California, U.S.A.

USGS Publications Warehouse

White, A.F.; Peterson, M.L.; Wollenberg, H.; Flexser, S.

1990-01-01

The isotopic ratios of H, O and C in water within the Long Valley caldera, California reflect input from sources external to the hydrothermal reservoir. A decrease in ??D in precipitation of 0.5??? km-1, from west to east across Long Valley, is caused by the introduction of less fractionated marine moisture through a low elevation embayment in the Sierra Nevada Mountain Range. Relative to seasonal fluctuations in precipitation (-158 to -35??.), ??D ranges in hot and cold surface and groundwaters are much less variable (-135 to -105??.). Only winter and spring moisture, reflecting higher precipitation rates with lighter isotopic signatures, recharge the hydrological system. The hydrothermal fluids are mixtures of isotopically heavy recharge (??D = - 115???, ??18O = - 15???) derived from the Mammoth embayment, and isotopically lighter cold water (??D = -135???, ??18O = -18???). This cold water is not representative of current local recharge. The ??13C values for dissolved carbon in hot water are significantly heavier (- 7 to - 3???) than in cold water (-18 to -10???) denoting a separate hydrothermal origin. These ??13C values overlie the range generally attributed to magmatic degassing of CO2. However, ??13C values of metamorphosed Paleozoic basement carbonates surrounding Long Valley fall in a similar range, indicating that hydrothermal decarbonization reactions are a probable source of CO2. The ??13C and ??18O values of secondary travertime and vein calcite indicate respective fractionation with CO2 and H2O at temperatures approximating current hydrothermal conditions. ?? 1990.

Global Emissions of Nitrous Oxide: Key Source Sectors, their Future Activities and Technical Opportunities for Emission Reduction

NASA Astrophysics Data System (ADS)

Winiwarter, W.; Höglund-Isaksson, L.; Klimont, Z.; Schöpp, W.; Amann, M.

2017-12-01

Nitrous oxide originates primarily from natural biogeochemical processes, but its atmospheric concentrations have been strongly affected by human activities. According to IPCC, it is the third largest contributor to the anthropogenic greenhouse gas emissions (after carbon dioxide and methane). Deep decarbonization scenarios, which are able to constrain global temperature increase within 1.5°C, require strategies to cut methane and nitrous oxide emissions on top of phasing out carbon dioxide emissions. Employing the Greenhouse gas and Air pollution INteractions and Synergies (GAINS) model, we have estimated global emissions of nitrous oxide until 2050. Using explicitly defined emission reduction technologies we demonstrate that, by 2030, about 26% ± 9% of the emissions can be avoided assuming full implementation of currently existing reduction technologies. Nearly a quarter of this mitigation can be achieved at marginal costs lower than 10 Euro/t CO2-eq with the chemical industry sector offering important reductions. Overall, the largest emitter of nitrous oxide, agriculture, also provides the largest emission abatement potentials. Emission reduction may be achieved by precision farming methods (variable rate technology) as well as by agrochemistry (nitrification inhibitors). Regionally, the largest emission reductions are achievable where intensive agriculture and industry are prevalent (production and application of mineral fertilizers): Centrally Planned Asia including China, North and Latin America, and South Asia including India. Further deep cuts in nitrous oxide emissions will require extending reduction efforts beyond strictly technological solutions, i.e., considering behavioral changes, including widespread adoption of "healthy diets" minimizing excess protein consumption.

Multistage hydrothermal silicification and Fe-Tl-As-Sb-Ge-REE enrichment in the Red Dog Zn-Pb-Ag district, northern Alaska: Geochemistry, origin, and exploration applications

USGS Publications Warehouse

Slack, J.F.; Kelley, K.D.; Anderson, V.M.; Clark, J.L.; Ayuso, R.A.

2004-01-01

Geochemical analyses of major, trace, and rare earth elements (REE) in more than 200 samples of variably silicified and altered wall rocks, massive and banded sulfide, silica rock, and sulfide-rich and unmineralized barite were obtained from the Main, Aqqaluk, and Anarraaq deposits in the Red Dog Zn-Pb-Ag district of northern Alaska. Detailed lithogeochemical profiles for two drill cores at Aqqaluk display an antithetic relationship between SiO2/Al2O3 and TiO2/Zr which, together with textural information, suggest preferential silicification of carbonate-bearing sediments. Data for both drill cores also show generally high Tl, Sb, As, and Ge and uniformly positive Eu anomalies (Eu/Eu* > 1.0). Similar high Tl, Sb, As, Ge, and Eu/Eu* values are present in the footwall and shallow hanging wall of Zn-Pb-Ag sulfide intervals at Anarraaq but are not as widely dispersed. Net chemical changes for altered wall rocks in the district, on the basis of average Al-normalized data relative to unaltered black shales of the host Kuna Formation, include large enrichments (>50%) of Fe, Ba, Eu, V, S, Co, Zn, Pb, Tl, As, Sb, and Ge at both Red Dog and Anarraaq, Si at Red Dog, and Sr, U, and Se at Anarraaq. Large depletions (>50%) are evident for Ca at both Red Dog and Anarraaq, for Mg, P, and Y at Red Dog, and for Na at Anarraaq. At both Red Dog and Anarraaq, wall-rock alteration removed calcite and minor dolomite during hydrothermal decarbonation reactions and introduced Si, Eu, and Ge during silicification. Sulfidation reactions deposited Fe, S, Co, Zn, Pb, Tl, As, and Sb; barite mineralization introduced Ba, S, and Sr. Light REE and U were mobilized locally. This alteration and mineralization occurred during Mississippi an hydrothermal events that predated the Middle Jurassic-Cretaceous Brookian orogeny. Early hydrothermal silicification at Red Dog took place prior to or during massive sulfide mineralization, on the basis of the dominantly planar nature of Zn-Pb veins, which suggests filling of fractures that developed in previously lithified rock. Uniformly low Ca and Mg and uniformly negative Ce anomalies in highly siliceous Red Dog wall rocks reflect hydrothermal decarbonation reactions and pervasive silicification owing to conductive cooling of oxidized metalliferous fluids. Similar Ca and Mg depletions are evident at Anarraaq but generally lack associated silicification, possibly because temperatures of the hydrothermal fluids were too low (<180??C) or because the thermal contrast between the fluids and wall rocks was smaller owing to the greater depth of alteration and mineralization there, compared with Red Dog. Chalcophile element anomalies (Fe, Zn, Pb, Tl, As, Sb) in wall rocks at both Red Dog and Anarraq are attributed to sulfidation reactions, coeval with subsurface Zn-Pb-Ag mineralization, during the mixing of oxidized metalliferous fluids with H2S-rich fluids derived locally within the Kuna Formation. Sedimentary wall rocks in the Red Dog district are characterized by a distinctive suite of geochemical anomalies, especially for Zn, Pb, Tl, As, Sb, Ge, and Eu/Eu*. At the Aqqaluk deposit, wall rocks without visible sphalerite or galena (<300 ppm Zn + Pb) have anomalous Eu/Eu*, Tl, Sb, and As for up to ???100 m stratigraphically below Zn-rich silica rock. At Anarraaq, the Tl anomaly is most extensively developed, and enrichment relative to unaltered black shale of the Kuna Formation is present up to 62 m above the highest Zn-Pb sulfide zones. The magnitude of the enrichment and systematic behavior of Tl in the district make Tl a promising geochemical exploration guide for Red Dog-type Zn-Pb-Ag deposits elsewhere. ?? 2004 by Economic Geology.

Pathways limiting warming to 1.5°C: a tale of turning around in no time?

NASA Astrophysics Data System (ADS)

Kriegler, Elmar; Luderer, Gunnar; Bauer, Nico; Baumstark, Lavinia; Fujimori, Shinichiro; Popp, Alexander; Rogelj, Joeri; Strefler, Jessica; van Vuuren, Detlef P.

2018-05-01

We explore the feasibility of limiting global warming to 1.5°C without overshoot and without the deployment of carbon dioxide removal (CDR) technologies. For this purpose, we perform a sensitivity analysis of four generic emissions reduction measures to identify a lower bound on future CO2 emissions from fossil fuel combustion and industrial processes. Final energy demand reductions and electrification of energy end uses as well as decarbonization of electricity and non-electric energy supply are all considered. We find the lower bound of cumulative fossil fuel and industry CO2 emissions to be 570 GtCO2 for the period 2016-2100, around 250 GtCO2 lower than the lower end of available 1.5°C mitigation pathways generated with integrated assessment models. Estimates of 1.5°C-consistent CO2 budgets are highly uncertain and range between 100 and 900 GtCO2 from 2016 onwards. Based on our sensitivity analysis, limiting warming to 1.5°C will require CDR or terrestrial net carbon uptake if 1.5°C-consistent budgets are smaller than 650 GtCO2. The earlier CDR is deployed, the more it neutralizes post-2020 emissions rather than producing net negative emissions. Nevertheless, if the 1.5°C budget is smaller than 550 GtCO2, temporary overshoot of the 1.5°C limit becomes unavoidable if CDR cannot be ramped up faster than to 4 GtCO2 in 2040 and 10 GtCO2 in 2050. This article is part of the theme issue `The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'.

Federal research, development, and demonstration priorities for carbon dioxide removal in the United States

NASA Astrophysics Data System (ADS)

Sanchez, Daniel L.; Amador, Giana; Funk, Jason; Mach, Katharine J.

2018-01-01

Atmospheric carbon dioxide removal (CDR) technologies may be critical to achieving deep decarbonization. Yet a lack of technical and commercial maturity of CDR technologies hinders potential deployment. Needs for commercialization span research, development, and demonstration (RD&D) activities, including development of new materials, reactors, and processes, and rigorous monitoring of a portfolio of demonstration projects. As a world leader in supporting science and engineering, the United States (US) can play an important role in reducing costs and clarifying the sustainable scale of CDR. To date, federal agencies have focused on voluntary or piecemeal CDR programs. Here, we present a synthesis of research and developement needs, relevant agency authority, barriers to coordination, and interventions to enhance RD&D across the federal government of the US. On the basis of agency authority and expertise, the Department of Energy, Department of Agriculture, Department of the Interior, National Oceanic and Atmospheric Administration, and National Science Foundation are most central to conducting research, funding projects, monitoring effects, and promulgating regulations. Key enablers for successful programs include embracing technological diversity and administrative efficiency, fostering agency buy-in, and achieving commercial deployment. Based on these criteria, the executive branch could effectively coordinate RD&D strategy through two complementary pathways: (1) renewing intra-agency commitment to CDR in five primary agencies, including both research and demonstration, and (2) coordinating research prioritization and outcomes across agencies, led by the Office of Science and Technology Policy and loosely based on the National Nanotechnology Initiative. Both pathways can be stimulated by executive order or Congressional mandate. Executive branch implementation can begin at any time; future Farm and Energy Bills provide legislative vehicles for enhancing programs.

No way out? The double-bind in seeking global prosperity along with mitigated climate change

NASA Astrophysics Data System (ADS)

Garrett, T. J.

2011-04-01

In a prior study (Garrett, 2011), I introduced a simple thermodynamics-based economic growth model. By treating civilization as a whole, it was found that the global economy's current rate of energy consumption can be tied through a constant to its current accumulation of wealth. The value of the constant is λ = 9.7 ± 0.3 milliwatts per 1990 US dollar. Here, this model is coupled to a linear formulation for the evolution of atmospheric CO2 concentrations. Despite the model's extreme simplicity, multi-decadal hindcasts of trajectories in gross world product (GWP) and CO2 agree closely with recent observations. Extending the model to the future, the model implies that the well-known IPCC SRES scenarios substantially underestimate how much CO2 levels will rise for a given level of future economic prosperity. Instead, what is shown is that, like a long-term natural disaster, future greenhouse warming should be expected to retard the real growth of wealth through inflationary pressures. Because wealth is tied to rates of energy consumption through the constant λ, it follows that dangerous climate change should be a negative feedback on CO2 emission rates, and therefore the ultimate extent of greenhouse warming. Nonetheless, if atmospheric CO2 concentrations are to remain below a "dangerous" level of 450 ppmv (Hansen et al., 2007), there will have to be some combination of an unrealistically rapid rate of energy decarbonization and a near immediate collapse of civilization wealth. Effectively, civilization is in a double-bind. If civilization does not collapse quickly this century, then CO2 levels will likely end up exceeding 1000 ppmv; but, if CO2 levels rise by this much, then the danger is that civilization will gradually tend towards collapse.

Pathways limiting warming to 1.5°C: a tale of turning around in no time?

PubMed

Kriegler, Elmar; Luderer, Gunnar; Bauer, Nico; Baumstark, Lavinia; Fujimori, Shinichiro; Popp, Alexander; Rogelj, Joeri; Strefler, Jessica; van Vuuren, Detlef P

2018-05-13

We explore the feasibility of limiting global warming to 1.5°C without overshoot and without the deployment of carbon dioxide removal (CDR) technologies. For this purpose, we perform a sensitivity analysis of four generic emissions reduction measures to identify a lower bound on future CO 2 emissions from fossil fuel combustion and industrial processes. Final energy demand reductions and electrification of energy end uses as well as decarbonization of electricity and non-electric energy supply are all considered. We find the lower bound of cumulative fossil fuel and industry CO 2 emissions to be 570 GtCO 2 for the period 2016-2100, around 250 GtCO 2 lower than the lower end of available 1.5°C mitigation pathways generated with integrated assessment models. Estimates of 1.5°C-consistent CO 2 budgets are highly uncertain and range between 100 and 900 GtCO 2 from 2016 onwards. Based on our sensitivity analysis, limiting warming to 1.5°C will require CDR or terrestrial net carbon uptake if 1.5°C-consistent budgets are smaller than 650 GtCO 2 The earlier CDR is deployed, the more it neutralizes post-2020 emissions rather than producing net negative emissions. Nevertheless, if the 1.5°C budget is smaller than 550 GtCO 2 , temporary overshoot of the 1.5°C limit becomes unavoidable if CDR cannot be ramped up faster than to 4 GtCO 2 in 2040 and 10 GtCO 2 in 2050.This article is part of the theme issue 'The Paris Agreement: understanding the physical and social challenges for a warming world of 1.5°C above pre-industrial levels'. © 2018 The Author(s).

Carbon capture by sorption-enhanced water-gas shift reaction process using hydrotalcite-based material

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

van Selow, E.R.; Cobden, P.D.; Verbraeken, P.A.

2009-05-15

A novel route for precombustion decarbonization is the sorption-enhanced water-gas shift (SEWGS) process. In this process carbon dioxide is removed from a synthesis gas at elevated temperature by adsorption. Simultaneously, carbon monoxide is converted to carbon dioxide by the water-gas shift reaction. The periodic adsorption and desorption of carbon dioxide is induced by a pressure swing cycle, and the cyclic capacity can be amplified by purging with steam. From previous studies is it known that for SEWGS applications, hydrotalcite-based materials are particularly attractive as sorbent, and commercial high-temperature shift catalysts can be used for the conversion of carbon monoxide. Tabletsmore » of a potassium promoted hydrotalcite-based material are characterized in both breakthrough and cyclic experiments in a 2 m tall fixed-bed reactor. When exposed to a mixture of carbon dioxide, steam, and nitrogen at 400{sup o}C, the material shows a breakthrough capacity of 1.4 mmol/g. In subsequent experiments the material was mixed with tablets of promoted iron-chromium shift catalyst and exposed to a mixture of carbon dioxide, carbon monoxide, steam, hydrogen, and nitrogen. It is demonstrated that carbon monoxide conversion can be enhanced to 100% in the presence of a carbon dioxide sorbent. At breakthrough, carbon monoxide and carbon dioxide simultaneously appear at the end of the bed. During more than 300 cycles of adsorption/reaction and desorption, the capture rate, and carbon monoxide conversion are confirmed to be stable. Two different cycle types are investigated: one cycle with a CO{sub 2} rinse step and one cycle with a steam rinse step. The performance of both SEWGS cycles are discussed.« less

Development and application of laser microprobe techniques for oxygen isotope analysis of silicates, and, fluid/rock interaction during and after granulite-facies metamorphism, highland southwestern complex, Sri Lanka

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

Elsenheimer, D.W.

1992-01-01

The extent of fluid/rock interaction within the crust is a function of crustal depth, with large hydrothermal systems common in the brittle, hydrostatically pressured upper crust, but restricted fluid flow in the lithostatically pressured lower crust. To quantify this fluid/rock interaction, a Nd-YAG/CO[sub 2] laser microprobe system was constructed to analyze oxygen isotope ratios in silicates. Developed protocols produce high precision in [sigma][sup 18]O ([+-]0.2, 1[sigma]) and accuracy comparable to conventional extraction techniques on samples of feldspar and quartz as small as 0.3mg. Analysis of sub-millimeter domains in quartz and feldspar in granite from the Isle of Skye, Scotland, revealsmore » complex intragranular zonation. Contrasting heterogeneous and homogeneous [sigma][sup 18]O zonation patterns are revealed in samples <10m apart. These differences suggest fluid flow and isotopic exchange was highly heterogeneous. It has been proposed that granulite-facies metamorphism in the Highland Southwestern Complex (HSWC), Sri Lanka, resulted from the pervasive influx of CO[sub 2], with the marbles and calc-silicates within the HSWC a proposed fluid source. The petrologic and stable isotopic characteristic of HSWC marbles are inconsistent with extensive decarbonation. Wollastonite calc-silicates occur as deformed bands and as post-metamorphis veins with isotopic compositions that suggest vein fluids that are at least in part magmatic. Post-metamorphic magmatic activity is responsible for the formation of secondary disseminated graphite growth in the HSWC. This graphite has magmatic isotopic compositions and is associated with vein graphite and amphibolite-granulite facies transitions zones. Similar features in Kerela Khondalite Belt, South India, may suggest a common metamorphic history for the two terranes.« less

Acoustic emissions imaging and synchrotron X-ray diffraction analysis of calcite at high pressure and temperature

NASA Astrophysics Data System (ADS)

Gasc, J.; Brantut, N.; Schubnel, A.; Brunet, F.; Mueller, H.

2008-12-01

We have monitored from in-situ X-ray diffraction coupled to Acoustic Emission (AE) imaging, the behavior of a fine grained synthetic calcite aggregate, at 0.66 GPa and for temperatures ranging from ambient to 1200° C. The powder sample was placed in a boron-epoxy assembly with an 8 mm edge-length and loaded in the MAX80 cubic multi-anvil press installed on the German synchrotron (HASYLAB-DESY, Hamburg). AE were recorded using five piezoceramic transducers (5 MHz eigen frequency) glued on each of the five WC anvils (4 side anvils and upper one). Full waveforms were acquired using an eight channel digital oscilloscope and located using the software Insite (ASC Ltd). Beyond 600° C, calcite grains started growing as evidenced by huge changes in the relative intensity of the diffraction lines. This is correlated to a sudden burst of AE which all located within the sample volume. These AE may indicate that stress relaxation, going on as intra-crystalline plasticity mechanisms were activated, released enough acoustic energy to be recorded and located. Although the diffraction data showed that grain growth continued beyond 800° C, the acoustic activity progressively decreased to below the sensitivity of our recording device (i.e. the triggering level). However, at temperature higher than 1000° C, a large number of AE were recorded again ( 2000 events). AE location revealed that the AE front progressed inwards the sample. The complete loss of diffraction signal and the post-mortem recovery of small amounts of CaO suggest that the second AE burst may be related to calcite melting/decarbonation. Perspectives include thorough microstructural analysis of the samples using electron microscopies (SEM and TEM) as well as a statistical and mechanical analysis of the acoustic data.

Authenticity of carbon dioxide bubbles in French ciders through multiflow-isotope ratio mass spectrometry measurements.

PubMed

Gaillard, Laetitia; Guyon, Francois; Salagoïty, Marie-Hélène; Médina, Bernard

2013-12-01

A procedure to detect whether carbon dioxide was added to French ciders has been developed. For this purpose, an optimised and simplified method is proposed to determine (13)C/(12)C isotope ratio of carbon dioxide (δ(13)C) in ciders. Three critical steps were checked: (1) influence of atmospheric CO2 remaining in the loaded vial, (2) impact of helium flush, (3) sampling speed. This study showed that atmospheric CO2 does not impact the measurement, that helium flush can lead to isotopic fractionation and finally, that a fractionation occurs only 5h after bottle opening. The method, without any other preparation, consists in sampling 0.2 mL of cold (4 °C) cider in a vial that is passed in an ultrasonic bath for 10 min at room temperature to enhance cider de-carbonation. The headspace CO2 is then analysed using the link Multiflow®-isotope ratio mass spectrometer. Each year, a data bank is developed by fermenting authentic apples juices in order to control cider authenticity. Over a four year span (2008-2011), the CO2 produced during the fermentation step was studied. This set of 61 authentic ciders, from various French production areas, was used to determine a δ(13)C value range of -22.59±0.92‰ for authentic ciders CO2 bubbles. 75 commercial ciders were analysed with this method. Most of the samples analysed present a gas δ(13)C value in the expected range. Nevertheless, some ciders have δ(13)C values outside the 3σ limit, revealing carbonation by technical CO2. This practice is not allowed for organic, "Controlled Appellation of Origin" ciders and ciders specifying natural carbonation on the label. Copyright © 2013 Elsevier Ltd. All rights reserved.

Field and petrological study of metasomatism and high-pressure carbonation from lawsonite eclogite-facies terrains, Alpine Corsica

NASA Astrophysics Data System (ADS)

Piccoli, Francesca; Vitale Brovarone, Alberto; Ague, Jay J.

2018-04-01

This study presents new field and petrological data on carbonated metasomatic rocks from the lawsonite-eclogite units of Alpine Corsica. These rocks form along major, slab-scale lithological boundaries of the subducted Alpine Tethys plate. Our results indicate that a large variety of rocks ranging from metamafic/ultramafic to metafelsic can react with carbon-bearing fluids, leading to carbon sequestration at high-pressure conditions. The process of carbonation includes both replacement of silicates by high-pressure carbonate, and carbonate veining. The field, microstructural and mineralogical data strongly suggest that the metasomatism was mediated by the infiltration of external fluids of mixed origin, including both mafic/ultramafic and metasedimentary sources. Our results support the following three-step evolution: (i) Release of aqueous fluids by lawsonite and/or antigorite breakdown at depth; (ii) Fluid channelization along the base of the metasedimentary pile of the subducted lithospheric plate and related reactive fluid flow leading to carbonate mineral dissolution; (iii) Further interactions of the resulting carbon-bearing fluids with slab-forming rocks at depths of ca. 70 km and carbonation of pre-existing silicate-rich lithologies. This study highlights the importance of carbonate-bearing fluids evolving along down-T, down-P paths, such as along slab-parallel lithological boundaries, for the sequestration of carbon in subduction zones, and suggests that similar processes may also operate in collisional settings. Fig. S2: Petrogenetic grid in the CaFMASH+CO2 system for the antigorite and clinopyroxene carbonation reactions, together with grossular forming reaction during decarbonation. Reactions are written with the high T assemblage to the right of the = sign.

Carbon isotope composition of CO2-rich inclusions in cumulate-forming mantle minerals from Stromboli volcano (Italy)

NASA Astrophysics Data System (ADS)

Gennaro, Mimma Emanuela; Grassa, Fausto; Martelli, Mauro; Renzulli, Alberto; Rizzo, Andrea Luca

2017-10-01

We report on measurements of concentration and carbon isotope composition (δ13CCO2) of CO2 trapped in fluid inclusions of olivine and clinopyroxene crystals separated from San Bartolo ultramafic cumulate Xenoliths (SBX) formed at mantle depth (i.e., beneath a shallow Moho supposed to be at 14.8 km). These cumulates, erupted about 2 ka ago at Stromboli volcano (Italy), have been already investigated by Martelli et al. (2014) mainly for Sr-Nd isotopes and for their noble gases geochemistry. The concentration of CO2 varies of one order of magnitude from 3.8·10- 8 mol g- 1 to 4.8·10- 7 mol g- 1, with δ13C values between - 2.8‰ and - 1.5‰ vs V-PDB. These values overlap the range of measurements performed in the crater gases emitted at Stromboli (- 2.5‰ < δ13CCO2 < - 1.0‰). Since SBX formed from relatively primitive mantle-derived basic magmas, we argue that the isotope composition displayed by fluid inclusions and surface gases can be considered representative of the magma volatile imprinting released by partial melting of the mantle source beneath Stromboli (- 2.8‰ < δ13C < - 1.0‰). In addition, the δ13C signature of CO2 is not significantly modified by fractionation due to magmatic degassing or intracrustal contamination processes owing to magma ascent and residence within the volcano plumbing system. Such δ13C values are higher than those commonly reported for MORB-like upper mantle (- 8 ÷ - 4‰) and likely reflect the source contamination of the local mantle wedge by CO2 coming from the decarbonation of the sediments carried by the subducting Ionian slab with a contribution of organic carbon up to 7%.

Geochemical study of travertines along middle-lower Tiber valley (central Italy): genesis, palaeo-environmental and tectonic implications

NASA Astrophysics Data System (ADS)

Giustini, Francesca; Brilli, Mauro; Mancini, Marco

2018-06-01

Several travertine deposits dating to the Pleistocene outcrop along the Tiber valley between Orte and Rome. Mineralogically, they are mainly composed of calcite; various lithofacies (stromatolitic, phytoclastic, and massive) were identified and relatively wide ranges of carbon (δ13C -8.11 to +11.42‰ vs. VPDB) and oxygen (δ18O +22.74 to +27.71‰ vs. VSMOW) isotope compositions were measured. The isotope and chemical compositions of water and free gases, in some cases associated with the travertines, were also measured. Carbon isotope data show that several samples fall in the typical range of thermogenic travertine, i.e., linked to the addition of deep inorganic CO2. The oxygen isotope composition of the springs associated with the travertine deposits points to travertine precipitation by slightly thermal water of meteoric origin. In general, these travertines are in association with, or close to, mineralised groundwaters (with slightly acidic pH, low thermalism, and enrichment in sulphates or sodium chloride) and rich CO2 gas emissions, the origin of which may be linked to decarbonation reactions. The travertine bodies are locally connected with crustal structural lineaments favouring the circulation of ascending deep CO2-rich fluids. Conversely, some samples show isotopic connotations of meteogenic deposits, representing travertines formed mainly from soil biogenic or atmospheric carbon dioxide generally present in shallow groundwater or surface water. According to their morphology and isotope data, these travertines may be attributed to the sedimentary environment of waterfalls. These new geochemical and morphological data are integrated with those already available in the literature regarding the study area and contribute to shedding light on palaeo-environmental conditions in western-central Italy during the Quaternary.

Towards a Model of Reactive-Cracking: the Role of Reactions, Elasticity and Surface Energy Driven Flow in Poro-elastic Media

NASA Astrophysics Data System (ADS)

Evans, O.; Spiegelman, M. W.; Wilson, C. R.; Kelemen, P. B.

2016-12-01

Many critical processes can be described by reactive fluid flow in brittle media, including hydration/alteration of oceanic plates near spreading ridges, chemical weathering, and dehydration/decarbonation of subducting plates. Such hydration reactions can produce volume changes that may induce stresses large enough to drive fracture in the rock, in turn exposing new reactive surface and modifying the permeability. A better understanding of this potentially rich feedback could also be critical in the design of engineered systems for geologic carbon sequestration. To aid understanding of these processes we have developed a macroscopic continuum description of reactive fluid flow in an elastically deformable porous media. We explore the behaviour of this model by considering a simplified hydration reaction (e.g. olivine + H20 -> serpentine + brucite). In a closed system, these hydration reactions will continue to consume available fluids until the permeability reaches zero, leaving behind it a highly stressed residuum. Our model demonstrates this limiting behaviour, and that the elastic stresses generated are large enough to cause failure/fracture of the host rock. Whilst it is understood that `reactive fracture' is an important mechanism for the continued evolution of this process, it is also proposed that imbibition/surface energy driven flow may play a role. Through a simplified set of computational experiments, we investigate the relative roles of elasticity and surface energy in both a non-reactive purely poro-elastic framework, and then in the presence of reaction. We demonstrate that surface energy can drive rapid diffusion of porosity, thus allowing the reaction to propagate over larger areas. As we expect both surface energy and fracture/failure to be of importance in these processes, we plan to integrate the current model into one that allows for fracture once critical stresses are exceeded.

Trends, application and future prospectives of microbial carbonic anhydrase mediated carbonation process for CCUS.

PubMed

Bhagat, C; Dudhagara, P; Tank, S

2018-02-01

Growing industrialization and the desire for a better economy in countries has accelerated the emission of greenhouse gases (GHGs), by more than the buffering capacity of the earth's atmosphere. Among the various GHGs, carbon dioxide occupies the first position in the anthroposphere and has detrimental effects on the ecosystem. For decarbonization, several non-biological methods of carbon capture, utilization and storage (CCUS) have been in use for the past few decades, but they are suffering from narrow applicability. Recently, CO 2 emission and its disposal related problems have encouraged the implementation of bioprocessing to achieve a zero waste economy for a sustainable environment. Microbial carbonic anhydrase (CA) catalyses reversible CO 2 hydration and forms metal carbonates that mimic the natural phenomenon of weathering/carbonation and is gaining merit for CCUS. Thus, the diversity and specificity of CAs from different micro-organisms could be explored for CCUS. In the literature, more than 50 different microbial CAs have been explored for mineral carbonation. Further, microbial CAs can be engineered for the mineral carbonation process to develop new technology. CA driven carbonation is encouraging due to its large storage capacity and favourable chemistry, allowing site-specific sequestration and reusable product formation for other industries. Moreover, carbonation based CCUS holds five-fold more sequestration capacity over the next 100 years. Thus, it is an eco-friendly, feasible, viable option and believed to be the impending technology for CCUS. Here, we attempt to examine the distribution of various types of microbial CAs with their potential applications and future direction for carbon capture. Although there are few key challenges in bio-based technology, they need to be addressed in order to commercialize the technology. © 2017 The Society for Applied Microbiology.

Quantifying the Impacts of Large Scale Integration of Renewables in Indian Power Sector

NASA Astrophysics Data System (ADS)

Kumar, P.; Mishra, T.; Banerjee, R.

2017-12-01

India's power sector is responsible for nearly 37 percent of India's greenhouse gas emissions. For a fast emerging economy like India whose population and energy consumption are poised to rise rapidly in the coming decades, renewable energy can play a vital role in decarbonizing power sector. In this context, India has targeted 33-35 percent emission intensity reduction (with respect to 2005 levels) along with large scale renewable energy targets (100GW solar, 60GW wind, and 10GW biomass energy by 2022) in INDCs submitted at Paris agreement. But large scale integration of renewable energy is a complex process which faces a number of problems like capital intensiveness, matching intermittent loads with least storage capacity and reliability. In this context, this study attempts to assess the technical feasibility of integrating renewables into Indian electricity mix by 2022 and analyze its implications on power sector operations. This study uses TIMES, a bottom up energy optimization model with unit commitment and dispatch features. We model coal and gas fired units discretely with region-wise representation of wind and solar resources. The dispatch features are used for operational analysis of power plant units under ramp rate and minimum generation constraints. The study analyzes India's electricity sector transition for the year 2022 with three scenarios. The base case scenario (no RE addition) along with INDC scenario (with 100GW solar, 60GW wind, 10GW biomass) and low RE scenario (50GW solar, 30GW wind) have been created to analyze the implications of large scale integration of variable renewable energy. The results provide us insights on trade-offs involved in achieving mitigation targets and investment decisions involved. The study also examines operational reliability and flexibility requirements of the system for integrating renewables.

Geochemical study of travertines along middle-lower Tiber valley (central Italy): genesis, palaeo-environmental and tectonic implications

NASA Astrophysics Data System (ADS)

Giustini, Francesca; Brilli, Mauro; Mancini, Marco

2017-09-01

Several travertine deposits dating to the Pleistocene outcrop along the Tiber valley between Orte and Rome. Mineralogically, they are mainly composed of calcite; various lithofacies (stromatolitic, phytoclastic, and massive) were identified and relatively wide ranges of carbon (δ13C -8.11 to +11.42‰ vs. VPDB) and oxygen (δ18O +22.74 to +27.71‰ vs. VSMOW) isotope compositions were measured. The isotope and chemical compositions of water and free gases, in some cases associated with the travertines, were also measured. Carbon isotope data show that several samples fall in the typical range of thermogenic travertine, i.e., linked to the addition of deep inorganic CO2. The oxygen isotope composition of the springs associated with the travertine deposits points to travertine precipitation by slightly thermal water of meteoric origin. In general, these travertines are in association with, or close to, mineralised groundwaters (with slightly acidic pH, low thermalism, and enrichment in sulphates or sodium chloride) and rich CO2 gas emissions, the origin of which may be linked to decarbonation reactions. The travertine bodies are locally connected with crustal structural lineaments favouring the circulation of ascending deep CO2-rich fluids. Conversely, some samples show isotopic connotations of meteogenic deposits, representing travertines formed mainly from soil biogenic or atmospheric carbon dioxide generally present in shallow groundwater or surface water. According to their morphology and isotope data, these travertines may be attributed to the sedimentary environment of waterfalls. These new geochemical and morphological data are integrated with those already available in the literature regarding the study area and contribute to shedding light on palaeo-environmental conditions in western-central Italy during the Quaternary.

Planning a Target Renewable Portfolio using Atmospheric Modeling and Stochastic Optimization

NASA Astrophysics Data System (ADS)

Hart, E.; Jacobson, M. Z.

2009-12-01

A number of organizations have suggested that an 80% reduction in carbon emissions by 2050 is a necessary step to mitigate climate change and that decarbonization of the electricity sector is a crucial component of any strategy to meet this target. Integration of large renewable and intermittent generators poses many new problems in power system planning. In this study, we attempt to determine an optimal portfolio of renewable resources to meet best the fluctuating California load while also meeting an 80% carbon emissions reduction requirement. A stochastic optimization scheme is proposed that is based on a simplified model of the California electricity grid. In this single-busbar power system model, the load is met with generation from wind, solar thermal, photovoltaic, hydroelectric, geothermal, and natural gas plants. Wind speeds and insolation are calculated using GATOR-GCMOM, a global-through-urban climate-weather-air pollution model. Fields were produced for California and Nevada at 21km SN by 14 km WE spatial resolution every 15 minutes for the year 2006. Load data for 2006 were obtained from the California ISO OASIS database. Maximum installed capacities for wind and solar thermal generation were determined using a GIS analysis of potential development sites throughout the state. The stochastic optimization scheme requires that power balance be achieved in a number of meteorological and load scenarios that deviate from the forecasted (or modeled) data. By adjusting the error distributions of the forecasts, the model describes how improvements in wind speed and insolation forecasting may affect the optimal renewable portfolio. Using a simple model, we describe the diversity, size, and sensitivities of a renewable portfolio that is best suited to the resources and needs of California and that contributes significantly to reduction of the state’s carbon emissions.

Adsorption of polar organic molecules on sediments: Case-study on Callovian-Oxfordian claystone.

PubMed

Rasamimanana, S; Lefèvre, G; Dagnelie, R V H

2017-08-01

The release and transport of anthropogenic organic matter through the geosphere is often an environmental criterion of safety. Sedimentary rocks are widely studied in this context as geological barriers for waste management. It is the case of Callovian-Oxfordian claystone (COx), for which several studies report adsorption of anthropogenic organic molecules. In this study, we evaluated and reviewed adsorption data of polar organic molecules on COx claystone. Experiments were performed on raw claystone, decarbonated and clay fractions. Adsorption isotherms were measured with adsorbates of various polarities: adipate, benzoate, ortho-phthalate, succinate, gluconate, oxalate, EDTA, citrate. A significant adsorption was observed for multidentate polycarboxylic acids as evidenced with phthalate, succinate, oxalate, gluconate, EDTA and citrate (R d  = 1.53, 3.52, 8.4, 8.8, 12.4, 54.7 L kg -1 respectively). Multiple linear regression were performed as a statistical analysis to determine the predictors from these adsorption data. A linear correlation between adsorption data (R d ) and dipole moment (μ) of adsorbates was evidenced (R 2  = 0.91). Molecules with a high dipole moment, μ(D) > 2.5, displayed a significant adsorption, R d ≫1 L kg -1 . A qualitative correlation can be easily estimated using the water/octanol partition coefficient, P ow , of adsorbates (R 2  = 0.77). In this case, two opposite trends were distinguished for polar and apolar molecules. The use of organic carbon content in sediments is relevant for predicting adsorption of apolar compounds, log (P ow )>+1. The oxides/clays contents may be relevant regarding polar molecules, log ( apparent P ow )<-1. The proposed scheme offers a general methodology for investigation of geo-barriers towards heterogeneous organic plumes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Systematic Planning of Adaptation Options for Pluvial Flood Resilience

NASA Astrophysics Data System (ADS)

Babovic, Filip; Mijic, Ana; Madani, Kaveh

2016-04-01

Different elements of infrastructure and the built environment vary in their ability to quickly adapt to changing circumstances. Furthermore, many of the slowest, and often largest infrastructure adaptations, offer the greatest improvements to system performance. In the context of de-carbonation of individual buildings Brand (1995) identified six potential layers of adaptation based on their renewal times ranging from daily to multi-decadal time scales. Similar layers exist in urban areas with regards to Water Sensitive Urban Design (WSUD) and pluvial flood risk. These layers range from appliances within buildings to changes in the larger urban form. Changes in low-level elements can be quickly implemented, but are limited in effectiveness, while larger interventions occur at a much slower pace but offer greater benefits as a part of systemic change. In the context of urban adaptation this multi-layered approach provides information on how to order urban adaptations. This information helps to identify potential pathways by prioritising relatively quick adaptations to be implemented in the short term while identifying options which require more long term planning with respect to both uncertainty and flexibility. This information is particularly critical in the evolution towards more resilient and water sensitive cities (Brown, 2009). Several potential adaptation options were identified ranging from small to large-scale adaptations. The time needed for the adaptation to be implemented was estimated and curves representing the added drainage capacity per year were established. The total drainage capacity added by each option was then established. This methodology was utilised on a case study in the Cranbrook Catchment in the North East of London. This information was able to provide insight on how to best renew or extend the life of critical ageing infrastructure.

Integrated life-cycle assessment of electricity-supply scenarios confirms global environmental benefit of low-carbon technologies.

PubMed

Hertwich, Edgar G; Gibon, Thomas; Bouman, Evert A; Arvesen, Anders; Suh, Sangwon; Heath, Garvin A; Bergesen, Joseph D; Ramirez, Andrea; Vega, Mabel I; Shi, Lei

2015-05-19

Decarbonization of electricity generation can support climate-change mitigation and presents an opportunity to address pollution resulting from fossil-fuel combustion. Generally, renewable technologies require higher initial investments in infrastructure than fossil-based power systems. To assess the tradeoffs of increased up-front emissions and reduced operational emissions, we present, to our knowledge, the first global, integrated life-cycle assessment (LCA) of long-term, wide-scale implementation of electricity generation from renewable sources (i.e., photovoltaic and solar thermal, wind, and hydropower) and of carbon dioxide capture and storage for fossil power generation. We compare emissions causing particulate matter exposure, freshwater ecotoxicity, freshwater eutrophication, and climate change for the climate-change-mitigation (BLUE Map) and business-as-usual (Baseline) scenarios of the International Energy Agency up to 2050. We use a vintage stock model to conduct an LCA of newly installed capacity year-by-year for each region, thus accounting for changes in the energy mix used to manufacture future power plants. Under the Baseline scenario, emissions of air and water pollutants more than double whereas the low-carbon technologies introduced in the BLUE Map scenario allow a doubling of electricity supply while stabilizing or even reducing pollution. Material requirements per unit generation for low-carbon technologies can be higher than for conventional fossil generation: 11-40 times more copper for photovoltaic systems and 6-14 times more iron for wind power plants. However, only two years of current global copper and one year of iron production will suffice to build a low-carbon energy system capable of supplying the world's electricity needs in 2050.

Revolutions in energy input and material cycling in Earth history and human history

NASA Astrophysics Data System (ADS)

Lenton, Timothy M.; Pichler, Peter-Paul; Weisz, Helga

2016-04-01

Major revolutions in energy capture have occurred in both Earth and human history, with each transition resulting in higher energy input, altered material cycles and major consequences for the internal organization of the respective systems. In Earth history, we identify the origin of anoxygenic photosynthesis, the origin of oxygenic photosynthesis, and land colonization by eukaryotic photosynthesizers as step changes in free energy input to the biosphere. In human history we focus on the Palaeolithic use of fire, the Neolithic revolution to farming, and the Industrial revolution as step changes in free energy input to human societies. In each case we try to quantify the resulting increase in energy input, and discuss the consequences for material cycling and for biological and social organization. For most of human history, energy use by humans was but a tiny fraction of the overall energy input to the biosphere, as would be expected for any heterotrophic species. However, the industrial revolution gave humans the capacity to push energy inputs towards planetary scales and by the end of the 20th century human energy use had reached a magnitude comparable to the biosphere. By distinguishing world regions and income brackets we show the unequal distribution in energy and material use among contemporary humans. Looking ahead, a prospective sustainability revolution will require scaling up new renewable and decarbonized energy technologies and the development of much more efficient material recycling systems - thus creating a more autotrophic social metabolism. Such a transition must also anticipate a level of social organization that can implement the changes in energy input and material cycling without losing the large achievements in standard of living and individual liberation associated with industrial societies.

Will the use of a carbon tax for revenue generation produce an incentive to continue carbon emissions?

NASA Astrophysics Data System (ADS)

Wang, Rong; Moreno-Cruz, Juan; Caldeira, Ken

2017-05-01

Integrated assessment models are commonly used to generate optimal carbon prices based on an objective function that maximizes social welfare. Such models typically project an initially low carbon price that increases with time. This framework does not reflect the incentives of decision makers who are responsible for generating tax revenue. If a rising carbon price is to result in near-zero emissions, it must ultimately result in near-zero carbon tax revenue. That means that at some point, policy makers will be asked to increase the tax rate on carbon emissions to such an extent that carbon tax revenue will fall. Therefore, there is a risk that the use of a carbon tax to generate revenue could eventually create a perverse incentive to continue carbon emissions in order to provide a continued stream of carbon tax revenue. Using the Dynamic Integrated Climate Economy (DICE) model, we provide evidence that this risk is not a concern for the immediate future but that a revenue-generating carbon tax could create this perverse incentive as time goes on. This incentive becomes perverse at about year 2085 under the default configuration of DICE, but the timing depends on a range of factors including the cost of climate damages and the cost of decarbonizing the global energy system. While our study is based on a schematic model, it highlights the importance of considering a broader spectrum of incentives in studies using more comprehensive integrated assessment models. Our study demonstrates that the use of a carbon tax for revenue generation could potentially motivate implementation of such a tax today, but this source of revenue generation risks motivating continued carbon emissions far into the future.

Integrated life-cycle assessment of electricity-supply scenarios confirms global environmental benefit of low-carbon technologies

PubMed Central

Hertwich, Edgar G.; Gibon, Thomas; Bouman, Evert A.; Arvesen, Anders; Heath, Garvin A.; Bergesen, Joseph D.; Ramirez, Andrea; Vega, Mabel I.; Shi, Lei

2015-01-01

Decarbonization of electricity generation can support climate-change mitigation and presents an opportunity to address pollution resulting from fossil-fuel combustion. Generally, renewable technologies require higher initial investments in infrastructure than fossil-based power systems. To assess the tradeoffs of increased up-front emissions and reduced operational emissions, we present, to our knowledge, the first global, integrated life-cycle assessment (LCA) of long-term, wide-scale implementation of electricity generation from renewable sources (i.e., photovoltaic and solar thermal, wind, and hydropower) and of carbon dioxide capture and storage for fossil power generation. We compare emissions causing particulate matter exposure, freshwater ecotoxicity, freshwater eutrophication, and climate change for the climate-change-mitigation (BLUE Map) and business-as-usual (Baseline) scenarios of the International Energy Agency up to 2050. We use a vintage stock model to conduct an LCA of newly installed capacity year-by-year for each region, thus accounting for changes in the energy mix used to manufacture future power plants. Under the Baseline scenario, emissions of air and water pollutants more than double whereas the low-carbon technologies introduced in the BLUE Map scenario allow a doubling of electricity supply while stabilizing or even reducing pollution. Material requirements per unit generation for low-carbon technologies can be higher than for conventional fossil generation: 11–40 times more copper for photovoltaic systems and 6–14 times more iron for wind power plants. However, only two years of current global copper and one year of iron production will suffice to build a low-carbon energy system capable of supplying the world's electricity needs in 2050. PMID:25288741

Land-Use Intensity of Electricity Production: Comparison Across Multiple Sources

NASA Astrophysics Data System (ADS)

Swain, M.; Lovering, J.; Blomqvist, L.; Nordhaus, T.; Hernandez, R. R.

2015-12-01

Land is an increasingly scarce global resource that is subject to competing pressures from agriculture, human settlement, and energy development. As countries concerned about climate change seek to decarbonize their power sectors, renewable energy sources like wind and solar offer obvious advantages. However, the land needed for new energy infrastructure is also an important environmental consideration. The land requirement of different electricity sources varies considerably, but there are very few studies that offer a normalized comparison. In this paper, we use meta-analysis to calculate the land-use intensity (LUI) of the following electricity generation sources: wind, solar photovoltaic (PV), concentrated solar power (CSP), hydropower, geothermal, nuclear, biomass, natural gas, and coal. We used data from existing studies as well as original data gathered from public records and geospatial analysis. Our land-use metric includes land needed for the generation facility (e.g., power plant or wind farm) as well as the area needed to mine fuel for natural gas, coal, and nuclear power plants. Our results found the lowest total LUI for nuclear power (115 ha/TWh/y) and the highest LUI for biomass (114,817 ha/TWh/y). Solar PV and CSP had a considerably lower LUI than wind power, but both were an order of magnitude higher than fossil fuels (which ranged from 435 ha/TWh/y for natural gas to 579 ha/TWh/y for coal). Our results suggest that a large build-out of renewable electricity, though it would offer many environmental advantages over fossil fuel power sources, would require considerable land area. Among low-carbon energy sources, relatively compact sources like nuclear and solar have the potential to reduce land requirements.

Evaluating the Cost, Safety, and Proliferation Risks of Small Floating Nuclear Reactors.

PubMed

Ford, Michael J; Abdulla, Ahmed; Morgan, M Granger

2017-11-01

It is hard to see how our energy system can be decarbonized if the world abandons nuclear power, but equally hard to introduce the technology in nonnuclear energy states. This is especially true in countries with limited technical, institutional, and regulatory capabilities, where safety and proliferation concerns are acute. Given the need to achieve serious emissions mitigation by mid-century, and the multidecadal effort required to develop robust nuclear governance institutions, we must look to other models that might facilitate nuclear plant deployment while mitigating the technology's risks. One such deployment paradigm is the build-own-operate-return model. Because returning small land-based reactors containing spent fuel is infeasible, we evaluate the cost, safety, and proliferation risks of a system in which small modular reactors are manufactured in a factory, and then deployed to a customer nation on a floating platform. This floating small modular reactor would be owned and operated by a single entity and returned unopened to the developed state for refueling. We developed a decision model that allows for a comparison of floating and land-based alternatives considering key International Atomic Energy Agency plant-siting criteria. Abandoning onsite refueling is beneficial, and floating reactors built in a central facility can potentially reduce the risk of cost overruns and the consequences of accidents. However, if the floating platform must be built to military-grade specifications, then the cost would be much higher than a land-based system. The analysis tool presented is flexible, and can assist planners in determining the scope of risks and uncertainty associated with different deployment options. © 2017 Society for Risk Analysis.

The direction of fluid flow during contact metamorphism of siliceous carbonate rocks: new data for the Monzoni and Predazzo aureoles, northern Italy, and a global review

NASA Astrophysics Data System (ADS)

Ferry, John M.; Wing, Boswell A.; Penniston-Dorland, Sarah C.; Rumble, Douglas

2002-03-01

Periclase formed in siliceous dolomitic marbles during contact metamorphism in the Monzoni and Predazzo aureoles, the Dolomites, northern Italy, by infiltration of the carbonate rocks by chemically reactive, H2O-rich fluids at 500 bar and 565-710 °C. The spatial distribution of periclase and oxygen isotope compositions is consistent with reactive fluid flow that was primarily vertical and upward in both aureoles with time-integrated flux ~5,000 and ~300 mol fluid/cm2 rock in the Monzoni and Predazzo aureoles, respectively. The new results for Monzoni and Predazzo are considered along with published studies of 13 other aureoles to draw general conclusions about the direction, amount, and controls on the geometry of reactive fluid flow during contact metamorphism of siliceous carbonate rocks. Flow in 12 aureoles was primarily vertically upward with and without a horizontal component directed away from the pluton. Fluid flow in two of the other three was primarily horizontal, directed from the pluton into the aureole. The direction of flow in the remaining aureole is uncertain. Earlier suggestions that fluid flow is often horizontal, directed toward the pluton, are likely explained by an erroneous assumption that widespread coexisting mineral reactants and products represent arrested prograde decarbonation reactions. With the exception of three samples from one aureole, time-integrated fluid flux was in the range 102-104 mol/cm2. Both the amount and direction of fluid flow are consistent with hydrodynamic models of contact metamorphism. The orientation of bedding and lithologic contacts appears to be the principal control over whether fluid flow was either primarily vertical or horizontal. Other pre-metamorphic structures, including dikes, faults, fold hinges, and fracture zones, served to channel fluid flow as well.

The direction of fluid flow during contact metamorphism of siliceous carbonate rocks: new data for the Monzoni and Predazzo aureoles, northern Italy, and a global review

NASA Astrophysics Data System (ADS)

Ferry, John; Wing, Boswell; Penniston-Dorland, Sarah; Rumble, Douglas

2001-11-01

Periclase formed in siliceous dolomitic marbles during contact metamorphism in the Monzoni and Predazzo aureoles, the Dolomites, northern Italy, by infiltration of the carbonate rocks by chemically reactive, H2O-rich fluids at 500 bar and 565-710 °C. The spatial distribution of periclase and oxygen isotope compositions is consistent with reactive fluid flow that was primarily vertical and upward in both aureoles with time-integrated flux 5,000 and 300 mol fluid/cm2 rock in the Monzoni and Predazzo aureoles, respectively. The new results for Monzoni and Predazzo are considered along with published studies of 13 other aureoles to draw general conclusions about the direction, amount, and controls on the geometry of reactive fluid flow during contact metamorphism of siliceous carbonate rocks. Flow in 12 aureoles was primarily vertically upward with and without a horizontal component directed away from the pluton. Fluid flow in two of the other three was primarily horizontal, directed from the pluton into the aureole. The direction of flow in the remaining aureole is uncertain. Earlier suggestions that fluid flow is often horizontal, directed toward the pluton, are likely explained by an erroneous assumption that widespread coexisting mineral reactants and products represent arrested prograde decarbonation reactions. With the exception of three samples from one aureole, time-integrated fluid flux was in the range 102-104 mol/cm2. Both the amount and direction of fluid flow are consistent with hydrodynamic models of contact metamorphism. The orientation of bedding and lithologic contacts appears to be the principal control over whether fluid flow was either primarily vertical or horizontal. Other pre-metamorphic structures, including dikes, faults, fold hinges, and fracture zones, served to channel fluid flow as well.

Hydrogen Vehicles: Impacts of DOE Technical Targets on Market Acceptance and Societal Benefits

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

Lin, Zhenhong; Dong, Jing; Greene, David L

2013-01-01

Hydrogen vehicles (H2V), including H2 internal combustion engine, fuel cell and fuel cell plugin hybrid, could greatly reduce petroleum consumption and greenhouse gas (GHG) emissions in the transportation sector. The U.S. Department of Energy has adopted targets for vehicle component technologies to address key technical barriers towidespread commercialization of H2Vs. This study estimates the market acceptance of H2Vs and the resulting societal benefits and subsidy in 41 scenarios that reflect a wide range of progress in meeting these technical targets. Important results include: (1) H2Vs could reach 20e70% market shares by 2050, depending on progress in achieving the technical targets.Withmore » a basic hydrogen infrastructure (w5% hydrogen availability), the H2V market share is estimated to be 2e8%. Fuel cell and hydrogen costs are the most important factors affecting the long-term market shares of H2Vs. (2) Meeting all technical targets on time could result in about an 80% cut in petroleumuse and a 62% (or 72% with aggressive electricity de-carbonization) reduction in GHG in 2050. (3) The required hydrogen infrastructure subsidy is estimated to range from $22 to $47 billion and the vehicle subsidy from $4 to $17 billion. (4) Long-term H2V market shares, societal benefits and hydrogen subsidies appear to be highly robust against delay in one target, if all other targets are met on time. R&D diversification could provide insurance for greater societal benefits. (5) Both H2Vs and plug-in electric vehicles could exceed 50% market shares by 2050, if all targets are met on time. The overlapping technology, the fuel cell plug-in hybrid electric vehicle, appears attractive both in the short and long runs, but for different reasons.« less

Metamorphic P-T conditions and CO2 influx history of medium-grade metapelites from Karakorum, Trans-Himalaya, India

NASA Astrophysics Data System (ADS)

Sachan, Himanshu K.; Santosh, M.; Prakash, Divya; Kharya, Aditya; Chandra Singh, P.; Rai, Santosh K.

2016-07-01

The medium grade metapelites of Pangong-Tso area in the trans-Himalayan region underwent sillimanite-grade metamorphism initiated during the Cretaceous, associated with the collision of the Kohistan arc and the Indian plate with Asia. This paper present results from a petrological and fluid inclusion study to understand the metamorphic P-T conditions and fluid history of these rocks. The calculated phase equilibria in the Na2O-CaO-K2O-FeO-MgO-MnO-Al2O3-SiO2-H2O-TiO2 (NCKFMMnASHT) system suggest P-T conditions of 8 kbar and 650 °C for the peak metamorphic event. Primary fluid inclusions occur in staurolite and garnet, whereas quartz carries mostly secondary fluid inclusions. The trapped fluids in primary inclusions show initial melting temperatures in the range of -56.9 to -56.6 °C, suggesting nearly pure CO2 composition. The secondary fluids are of mixed carbonic-aqueous nature. The re-equilibrated inclusions show annular morphology as well as necking phenomena. The CO2 isochores for the primary inclusions indicate pressures of 6.1-6.7 kbar, suggesting that the CO2-rich fluids were trapped during post-peak exhumation of the rocks, or that synmetamorphic carbonic fluids underwent density reversal during isothermal decompression. The secondary CO2-H2O fluids must have been trapped during the late exhumation stage, as their isochores define further lower pressures of 4.8 kbar. The morphology of re-equilibrated fluid inclusions and the rapid decrease in pressure are consistent with a near-isothermal decompression trajectory following the peak metamorphism. The carbonic fluids were probably derived locally from decarbonation reactions of the associated carbonate rocks during metamorphism or from a deep-seated reservoir through Karakorum fault.

Advanced Demonstration and Test Reactor Options Study

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

Petti, David Andrew; Hill, R.; Gehin, J.

Global efforts to address climate change will require large-scale decarbonization of energy production in the United States and elsewhere. Nuclear power already provides 20% of electricity production in the United States (U.S.) and is increasing in countries undergoing rapid growth around the world. Because reliable, grid-stabilizing, low emission electricity generation, energy security, and energy resource diversity will be increasingly valued, nuclear power’s share of electricity production has a potential to grow. In addition, there are non electricity applications (e.g., process heat, desalination, hydrogen production) that could be better served by advanced nuclear systems. Thus, the timely development, demonstration, and commercializationmore » of advanced nuclear reactors could diversify the nuclear technologies available and offer attractive technology options to expand the impact of nuclear energy for electricity generation and non-electricity missions. The purpose of this planning study is to provide transparent and defensible technology options for a test and/or demonstration reactor(s) to be built to support public policy, innovation and long term commercialization within the context of the Department of Energy’s (DOE’s) broader commitment to pursuing an “all of the above” clean energy strategy and associated time lines. This planning study includes identification of the key features and timing needed for advanced test or demonstration reactors to support research, development, and technology demonstration leading to the commercialization of power plants built upon these advanced reactor platforms. This planning study is consistent with the Congressional language contained within the fiscal year 2015 appropriation that directed the DOE to conduct a planning study to evaluate “advanced reactor technology options, capabilities, and requirements within the context of national needs and public policy to support innovation in nuclear energy”. Advanced reactors are defined in this study as reactors that use coolants other than water. Advanced reactor technologies have the potential to expand the energy applications, enhance the competitiveness, and improve the sustainability of nuclear energy.« less

Emissions Scenario Portal for Visualization of Low Carbon Pathways

NASA Astrophysics Data System (ADS)

Friedrich, J.; Hennig, R. J.; Mountford, H.; Altamirano, J. C.; Ge, M.; Fransen, T.

2016-12-01

This proposal for a presentation is centered around a new project which is developed collaboratively by the World Resources Institute (WRI), Google Inc., and Deep Decarbonization Pathways Project (DDPP). The project aims to develop an online, open portal, the Emissions Scenario Portal (ESP),to enable users to easily visualize a range of future greenhouse gas emission pathways linked to different scenarios of economic and energy developments, drawing from a variety of modeling tools. It is targeted to users who are not modelling experts, but instead policy analysts or advisors, investment analysts, and similar who draw on modelled scenarios to inform their work, and who can benefit from better access to, and transparency around, the wide range of emerging scenarios on ambitious climate action. The ESP will provide information from scenarios in a visually appealing and easy-to-understand manner that enable these users to recognize the opportunities to reduce GHG emissions, the implications of the different scenarios, and the underlying assumptions. To facilitate the application of the portal and tools in policy dialogues, a series of country-specific and potentially sector-specific workshops with key decision-makers and analysts, supported by relevant analysis, will be organized by the key partners and also in broader collaboration with others who might wish to convene relevant groups around the information. This project will provide opportunities for modelers to increase their outreach and visibility in the public space and to directly interact with key audiences of emissions scenarios, such as policy analysts and advisors. The information displayed on the portal will cover a wide range of indicators, sectors and important scenario characteristics such as macroeconomic information, emission factors and policy as well as technology assumptions in order to facilitate comparison. These indicators have been selected based on existing standards (such as the IIASA AR5 database, the Greenhouse Gas Protocol and accounting literature) and stakeholder consultations. Examples for use cases include: technical advisers for governments NGO/Civil Society advocates Investors and bankers Modelers and academics Business sustainability officers

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

Wei, Max; Smith, Sarah J.; Sohn, Michael D.

Fuel cells are both a longstanding and emerging technology for stationary and transportation applications, and their future use will likely be critical for the deep decarbonization of global energy systems. As we look into future applications, a key challenge for policy-makers and technology market forecasters who seek to track and/or accelerate their market adoption is the ability to forecast market costs of the fuel cells as technology innovations are incorporated into market products. Specifically, there is a need to estimate technology learning rates, which are rates of cost reduction versus production volume. Unfortunately, no literature exists for forecasting future learningmore » rates for fuel cells. In this paper, we look retrospectively to estimate learning rates for two fuel cell deployment programs: (1) the micro-combined heat and power (CHP) program in Japan, and (2) the Self-Generation Incentive Program (SGIP) in California. These two examples have a relatively broad set of historical market data and thus provide an informative and international comparison of distinct fuel cell technologies and government deployment programs. We develop a generalized procedure for disaggregating experience-curve cost-reductions in order to disaggregate the Japanese fuel cell micro-CHP market into its constituent components, and we derive and present a range of learning rates that may explain observed market trends. Finally, we explore the differences in the technology development ecosystem and market conditions that may have contributed to the observed differences in cost reduction and draw policy observations for the market adoption of future fuel cell technologies. The scientific and policy contributions of this paper are the first comparative experience curve analysis of past fuel cell technologies in two distinct markets, and the first quantitative comparison of a detailed cost model of fuel cell systems with actual market data. The resulting approach is applicable to analyzing other fuel cell markets and other energy-related technologies, and highlights the data needed for cost modeling and quantitative assessment of key cost reduction components.« less

Frictional processes during flank motion at Mount Etna (Italy): experimental characterisation of slip on similar and dissimilar volcanic and sedimentary rocks.

NASA Astrophysics Data System (ADS)

Rozanski, Wojciech; Lavallee, Yan; Kendrick, Jackie; Castagna, Angela; Mitchell, Thomas; Heap, Michael; Vinciguerra, Sergio; Hirose, Takehiro; Dingwell, Donald

2015-04-01

The edifice of Mount Etna (Italy) is structurally unstable, exhibiting a near continuous ESE seaward sliding along a set of faults due to interplay between regional tectonics, gravity instability and magma intrusion. Continuous seismic and ground deformation monitoring reveals the resulting large-scale flank motion at variable rates. The mechanisms controlling this faulting kinetic remains, however, poorly constrained. Examination of the fault zones reveals a range of rock types along the different fault segments: fresh and altered basalt, clay and limestone. As lithological contrasts can jeopardise the structural stability of an edifice, we experimentally investigate the frictional properties of these rocks using low- to high-velocity-rotary shear tests on similar and dissimilar rocks to better understand episodes of slow flank motion as well as rapid and catastrophic sector collapse events. The first set of experiments was performed at velocities up to 1.2 m/s and at normal stresses of 1.5 MPa, commensurate with depths of the contacts seen in the Etna edifice. Friction experiments on clay gouge shows the strong rate-weakening dependence of slip in this material as well as the release of carbon dioxide. Friction experiments on solid rocks show a wider range of mechanical behaviour. At high velocity (>0.6 m/s) volcanic rocks tend to melt whereas the clay and limestone do not; rather they decarbonate, which prevents the rock from achieving the temperature required for melting. Experiments on dissimilar rocks clearly show that composition of host rocks affects the composition and viscosity of the resultant frictional melt, which can have a dramatic effect on shear stress leading to fault weakening or strengthening depending on the combination of host rock samples. A series of low- to moderate-slip velocity experiments is now being conducted to complement our dataset and provide a more complete rock friction model applicable to Mount Etna.

Biogeochemical potential of biomass pyrolysis systems for limiting global warming to 1.5 °C

NASA Astrophysics Data System (ADS)

Werner, C.; Schmidt, H.-P.; Gerten, D.; Lucht, W.; Kammann, C.

2018-04-01

Negative emission (NE) technologies are recognized to play an increasingly relevant role in strategies limiting mean global warming to 1.5 °C as specified in the Paris Agreement. The potentially significant contribution of pyrogenic carbon capture and storage (PyCCS) is, however, highly underrepresented in the discussion. In this study, we conduct the first quantitative assessment of the global potential of PyCCS as a NE technology based on biomass plantations. Using a process-based biosphere model, we calculate the land use change required to reach specific climate mitigation goals while observing biodiversity protection guardrails. We consider NE targets of 100–300 GtC following socioeconomic pathways consistent with a mean global warming of 1.5 °C as well as the option of additional carbon balancing required in case of failure or delay of decarbonization measures. The technological opportunities of PyCCS are represented by three tracks accounting for the sequestration of different pyrolysis products: biochar (as soil amendment), bio-oil (pumped into geological storages) and permanent-pyrogas (capture and storage of CO2 from gas combustion). In addition, we analyse how the gain in land induced by biochar-mediated yield increases on tropical cropland may reduce the pressure on land. Our results show that meeting the 1.5 °C goal through mitigation strategies including large-scale NE with plantation-based PyCCS may require conversion of natural vegetation to biomass plantations in the order of 133–3280 Mha globally, depending on the applied technology and the NE demand. Advancing towards additional bio-oil sequestration reduces land demand considerably by potentially up to 60%, while the benefits from yield increases account for another 3%–38% reduction (equalling 82–362 Mha). However, when mitigation commitments are increased by high balancing claims, even the most advanced PyCCS technologies and biochar-mediated co-benefits cannot compensate for delayed action towards phasing-out fossil fuels.

The Lavrion Pb-Zn-Fe-Cu-Ag detachment-related district (Attica, Greece): Structural control on hydrothermal flow and element transfer-deposition

NASA Astrophysics Data System (ADS)

Scheffer, Christophe; Tarantola, Alexandre; Vanderhaeghe, Olivier; Voudouris, Panagiotis; Rigaudier, Thomas; Photiades, Adonis; Morin, Denis; Alloucherie, Alison

2017-10-01

The impact of lithological heterogeneities on deformation, fluid flow and ore deposition is discussed based on the example of the Lavrion low-angle detachment partly accommodating gravitational collapse of the Hellenides orogenic belt in Greece. The Lavrion peninsula is characterised by a multiphase Pb-Zn-Fe-Cu-Ag ore system with a probable pre-concentration before subduction followed by progressive remobilisation and deposition coeval with the development of a low-angle ductile to brittle shear zone. The mylonitic marble below the detachment shear zone is composed of white layers of pure marble alternating with blue layers containing impurities (SiO2, Al2O3, carbonaceous material). Ductile mylonitic deformation is more pervasive in the less competent impure blue marble. We propose that localised deformation in the impure marble is associated with fluid circulation and dolomitisation, which in turn causes an increase in competence of these layers. Mineralised cataclastic zones, crosscutting the mylonitic fabric, are preferentially localised in the more competent dolomitic layers. Oxygen and carbon isotopic signatures of marble invaded by carbonate replacement deposits during ductile to ductile-brittle deformation are consistent with decarbonation coeval with the invasion of magmatic fluids. Mineralised cataclastic zones reflecting brittle deformation evolve from low 13C to low 18O signatures, interpreted as local interaction with carbonaceous material that trends toward the contribution of a surface-derived fluid. These features indicate that the Lavrion area records a complex deposition history influenced by the evolution of fluid reservoirs induced by the thermal and mechanical evolution of the marble nappe stack. Ore remobilisation and deposition associated with the activity of the low-angle detachment is (i) firstly related to the intrusion of the Plaka granodiorite leading to porphyry-type and carbonate replacement mineralisation during ductile-brittle deformation and (ii) then marked by progressive penetration of surface-derived fluids guided by strain localisation in the more competent levels leading to epithermal mineralisation associated with brittle deformation.

China's Pathways to Achieving 40% ~ 45% Reduction in CO{sub 2} Emissions per Unit of GDP in 2020: Sectoral Outlook and Assessment of Savings Potential

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

Zheng, Nina; Fridley, David; Zhou, Nan

2011-09-30

Achieving China’s goal of reducing its carbon intensity (CO{sub 2} per unit of GDP) by 40% to 45% percent below 2005 levels by 2020 will require the strengthening and expansion of energy efficiency policies across the buildings, industries and transport sectors. This study uses a bottom-up, end-use model and two scenarios -- an enhanced energy efficiency (E3) scenario and an alternative maximum technically feasible energy efficiency improvement (Max Tech) scenario – to evaluate what policies and technical improvements are needed to achieve the 2020 carbon intensity reduction target. The findings from this study show that a determined approach by Chinamore » can lead to the achievement of its 2020 goal. In particular, with full success in deepening its energy efficiency policies and programs but following the same general approach used during the 11th Five Year Plan, it is possible to achieve 49% reduction in CO{sub 2} emissions per unit of GDP (CO{sub 2} emissions intensity) in 2020 from 2005 levels (E3 case). Under the more optimistic but feasible assumptions of development and penetration of advanced energy efficiency technology (Max Tech case), China could achieve a 56% reduction in CO{sub 2} emissions intensity in 2020 relative to 2005 with cumulative reduction of energy use by 2700 Mtce and of CO{sub 2} emissions of 8107 Mt CO{sub 2} between 2010 and 2020. Energy savings and CO{sub 2} mitigation potential varies by sector but most of the energy savings potential is found in energy-intensive industry. At the same time, electricity savings and the associated emissions reduction are magnified by increasing renewable generation and improving coal generation efficiency, underscoring the dual importance of end-use efficiency improvements and power sector decarbonization.« less

Nitrogen Isotopic Study of Benthic Macroalgae and Seawater in Biscayne Bay, Florida

NASA Astrophysics Data System (ADS)

Drayer, C. L.; Lamb, K. A.; Swart, P. K.; Altabet, M. A.; Anderson, W. T.; Bellmund, S.

2006-12-01

Biscayne Bay, Florida is a complex coastal environment with many possible natural and anthropogenic sources of nitrogen. Such sources include precipitation, N fixation, nutrient regeneration/recycling, landfill soil leaching, groundwater and agricultural runoff, septic tank leakage, and treated waste water effluent. In order to understand the relative importance of these various inputs, benthic macroalgae, seagrasses, and seawater samples were collected from Biscayne Bay transecting from canals through nearshore bay to offshore reef sites Macroalgae was identified by species, decarbonated, and analyzed for δ15N and δ13C. The mean δ15N and δ13C for the algal tissue were +5.4 (±0.3‰) and -15.1 (±0.1‰), respectively. Measured nearshore algal samples differed greatly from offshore samples and had a high δ15N value of +12.0 (±0.1‰) and a mean of +8.6 (±3.0‰), in comparison to offshore samples that averaged +4.7 (±2.5‰). Despite the variation in δ15N, the δ13C values for both nearshore and offshore samples fell within the accepted parameters for algal communities. Seawater was analyzed for δ15N in DIN (dissolved inorganic nitrogen) and DON (dissolved organic nitrogen) through the cadmium reduction method (Mcllvin and Altabet, 2005). The mean δ15N for the DIN was +4.5 (±3.9‰) and the DON was +5.8 (±3.3‰). Canal DON δ15N values contained the heaviest measured values at ~+18‰, while nearshore and offshore DON values were lighter, 4.9 (±1.6‰). DIN values were more spatially variable with canal and nearshore sites ranging from ~+10‰ through ~-4.5‰. This study will continue over the next two years to examine possible temporal C and N isotope variations and will expand to include a larger geographic region focusing on areas with high nutrient levels and harmful algae blooms (HABs).

Multi-scale characterization of pore evolution in a combustion metamorphic complex, Hatrurim basin, Israel: Combining (ultra) small-angle neutron scattering and image analysis

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

Wang, Hsiu-Wen; Anovitz, Lawrence; Burg, Avihu

Backscattered scanning electron micrograph and ultra small- and small-angle neutron scattering data have been combined to provide statistically meaningful data on the pore/grain structure and pore evolution of combustion metamorphic complexes from the Hatrurim basin, Israel. Three processes, anti-sintering roughening, alteration of protolith (dehydration, decarbonation, and oxidation) and crystallization of high-temperature minerals, occurred simultaneously, leading to significant changes in observed pore/grain structures. Pore structures in the protoliths, and in lowand high-grade metamorphic rocks show surface (Ds) and mass (Dm) pore fractal geometries with gradual increases in both Ds and Dm values as a function of metamorphic grade. This suggests thatmore » increases in pore volume and formation of less branching pore networks are accompanied by a roughening of pore/grain interfaces. Additionally, pore evolution during combustion metamorphism is also characterized by reduced contributions from small-scale pores to the cumulative porosity in the high-grade rocks. At high temperatures, small-scale pores may be preferentially closed by the formation of high-temperature minerals, producing a rougher morphology with increasing temperature. Alternatively, large-scale pores may develop at the expense of small-scale pores. These observations (pore fractal geometry and cumulative porosity) indicate that the evolution of pore/grain structures is correlated with the growth of high-temperature phases and is a consequence of the energy balance between pore/grain surface energy and energy arising from heterogeneous phase contacts. The apparent pore volume density further suggests that the localized time/temperature development of the high-grade Hatrurim rocks is not simply an extension of that of the low-grade rocks. The former likely represents the "hot spots (burning foci)" in the overall metamorphic terrain while the latter may represent contact aureoles.« less

The electrical conductivity during incipient melting in the oceanic low velocity zone

NASA Astrophysics Data System (ADS)

Gaillard, Fabrice; Sifre, David; Gardes, Emmanuel; Massuyeau, Malcolm; Hashim, Leila; Hier Majumder, Saswata

2014-05-01

A low viscosity layer at the Lithosphere-Asthenosphere Boundary (LAB) is certainly a requirement for plate tectonics but the nature of the rocks presents in this boundary remains controversial. The seismic low velocities and the high electrical conductivities of the LAB are attributed either to sub-solidus water-related defects in olivine minerals or to a few volume percents of partial melt but these two interpretations have shortcomings: (1) The amount of H2O stored in olivine is not expected to be high enough due to several mineralogical processes that have been sometimes ignored; (2) elevated melt volume fractions are impeded by the too cold temperatures prevailing in the LAB and by the high melt mobility that can lead to gravitational segregation. All this has in fact been partly settled 30 years ago, when a petrological LAB has been defined as a region of the upper mantle impregnated by incipient melts; that is small amounts of melt caused by small amount of CO2 and H2O. We show here that incipient melting is a melting regime that is allowed in the entire P-T-fO2 region of the LVZ. The top of the oceanic LVZ (LAB) is then best explained by a melt freezing layer due to a decarbonation reaction, whereas the bottom of the LVZ matches the depth at which redox melting defines the lower boundary of stability of incipient melts. Based on new laboratory measurements, we show here that incipient melts must be the cause of the high electrical conductivities in the oceanic LVZ. Considering relevant mantle abundances of H2O and CO2 and their effect on the petrology of incipient melting, we calculated conductivity profiles across the LAB for various ages. Several electrical discontinuities are predicted and match geophysical observations in a consistent petrological and geochemical framework. We conclude that incipient melts prevail in the LAB, what else?

A Marginal Cost Based "Social Cost of Carbon" Provides Inappropriate Guidance in a World That Needs Rapid and Deep Decarbonization

NASA Astrophysics Data System (ADS)

Morgan, M. G.; Vaishnav, P.; Azevedo, I. L.; Dowlatabadi, H.

2016-12-01

Rising temperatures and changing precipitation patterns due to climate change are projected to alter many sectors of the US economy. A growing body of research has examined these effects in the energy, water, and agricultural sectors. Rising summer temperatures increase the demand for electricity. Changing precipitation patterns effect the availability of water for hydropower generation, thermo-electric cooling, irrigation, and municipal and industrial consumption. A combination of changes to temperature and precipitation alter crop yields and cost-effective farming practices. Although a significant body of research exists on analyzing impacts to individual sectors, fewer studies examine the effects using a common set of assumptions (e.g., climatic and socio-economic) within a coupled modeling framework. The present analysis uses a multi-sector, multi-model framework with common input assumptions to assess the projected effects of climate change on energy, water, and land-use in the United States. The analysis assesses the climate impacts for across 5 global circulation models for representative concentration pathways (RCP) of 8.5 and 4.5 W/m2. The energy sector models - Pacific Northwest National Lab's Global Change Assessment Model (GCAM) and the National Renewable Energy Laboratory's Regional Energy Deployment System (ReEDS) - show the effects of rising temperature on energy and electricity demand. Electricity supply in ReEDS is also affected by the availability of water for hydropower and thermo-electric cooling. Water availability is calculated from the GCM's precipitation using the US Basins model. The effects on agriculture are estimated using both a process-based crop model (EPIC) and an agricultural economic model (FASOM-GHG), which adjusts water supply curves based on information from US Basins. The sectoral models show higher economic costs of climate change under RCP 8.5 than RCP 4.5 averaged across the country and across GCM's.

A Chlorine-Centric Perspective on Fluid-Mediated Processes at Convergent Plate Boundaries

NASA Astrophysics Data System (ADS)

Selverstone, J.

2014-12-01

The release and migration of metamorphic fluids from subducting slabs into overlying mantle is widely recognized as a major mechanism in producing arc geochemical signatures and returning fluid-mobile elements to earth's crust and surface environments. Although the magnitudes of many geochemical fluxes are well constrained, the processes whereby mass transfer occurs in different portions of the subduction system are less well known. Chlorine stable isotopes provide a new perspective on some of these processes: Cl is hydrophilic, but decarbonation reactions favor Cl retention in minerals. Cl also shows less isotopic fractionation than other fluid-sensitive systems and may thus preserve evidence of specific fluid sources and/or fluid mixing events. Detailed studies of sedimentary sequences show that individual beds are isotopically homogeneous but large heterogeneities in δ37Cl exist across beds on a cm to m scale and vary as a function of depositional environment. Compositionally correlative medium-, high-, and ultrahigh-pressure metamorphic sequences in the Alps record decreases of 30-50% in Cl contents in the earliest stages of metamorphism, but little change thereafter. No statistically significant change in isotopic composition occurs during prograde metamorphism of individual horizons, and the same large degree of isotopic heterogeneity (up to 6‰) persists throughout the prograde devolatilization history of the rocks. Likewise, analysis of HP/UHP serpentinites and altered oceanic crust show that heterogeneous protolith compositions are preserved during transport to sub-arc depths, despite large-scale devolatilization. However, upward transport of rocks within the subduction channel results in highly localized interaction with isotopically distinct, Cl-bearing fluid packets. Overlying forearc wedge rocks also record heterogeneous and channelized interaction with distinct fluid components with different δ37Cl. Within-layer fluid compartmentalization during continuous devolatilization reactions must thus be reconciled with discontinuous, cross-layer fluid percolation out of the slab and into the wedge. The resulting implications of the chlorine data for recent mechanical models of slab-to-wedge fluid transport will be discussed.

Low-carbon electricity production through the implementation of photovoltaic panels in rooftops in urban environments: A case study for three cities in Peru.

PubMed

Bazán, José; Rieradevall, Joan; Gabarrell, Xavier; Vázquez-Rowe, Ian

2018-05-01

Urban environments in Latin America must begin decarbonizing their activities to avoid increasing greenhouse gases (GHGs) emissions rates due to their reliance on fossil fuel-based energy to support economic growth. In this context, cities in Latin America have high potential to convert sunlight into energy. Hence, the main objective of this study was to determine the potential of electricity self-sufficiency production and mitigation of GHG emissions in three medium-sized cities in Peru through the revalorization of underutilized rooftop areas in urban environments. Each city represented a distinct natural area of Peru: Pacific coast, Andean region and Amazon basin. More specifically, photovoltaic solar systems were the technology selected for implementation in these rooftop areas. Data on incident solar energy, temperature and energy consumption were collected. Thereafter, ArcGis10.3 was used to quantify the total usable area in the cities. A series of correction factors, including tilt, orientation or roof profiles were applied to attain an accurate value of usable area. Finally, Life Cycle Assessment was the methodology chosen to calculate the reduction of environmental impacts as compared to the current context of using electricity from the regional grids. Results showed that the cities assessed have the potential to obtain their entire current electricity demand for residential, commercial and public lighting purposes, augmenting energy security and resilience to intermittent natural disasters, with the support of decentralized storage systems. This approach would also translate into substantial reductions in terms of GHG emissions. Annual reductions in GHG emissions ranged from 112ton CO 2 eq in the city of Ayacucho to over 523kton CO 2 eq in Pucallpa, showing that cities in the Amazon basin would be the ones that benefit the most in terms of climate change mitigation. Copyright © 2017 Elsevier B.V. All rights reserved.

No way out? The double-bind in seeking global prosperity alongside mitigated climate change

NASA Astrophysics Data System (ADS)

Garrett, T. J.

2012-01-01

In a prior study (Garrett, 2011), I introduced a simple economic growth model designed to be consistent with general thermodynamic laws. Unlike traditional economic models, civilization is viewed only as a well-mixed global whole with no distinction made between individual nations, economic sectors, labor, or capital investments. At the model core is a hypothesis that the global economy's current rate of primary energy consumption is tied through a constant to a very general representation of its historically accumulated wealth. Observations support this hypothesis, and indicate that the constant's value is λ = 9.7 ± 0.3 milliwatts per 1990 US dollar. It is this link that allows for treatment of seemingly complex economic systems as simple physical systems. Here, this growth model is coupled to a linear formulation for the evolution of globally well-mixed atmospheric CO2 concentrations. While very simple, the coupled model provides faithful multi-decadal hindcasts of trajectories in gross world product (GWP) and CO2. Extending the model to the future, the model suggests that the well-known IPCC SRES scenarios substantially underestimate how much CO2 levels will rise for a given level of future economic prosperity. For one, global CO2 emission rates cannot be decoupled from wealth through efficiency gains. For another, like a long-term natural disaster, future greenhouse warming can be expected to act as an inflationary drag on the real growth of global wealth. For atmospheric CO2 concentrations to remain below a "dangerous" level of 450 ppmv (Hansen et al., 2007), model forecasts suggest that there will have to be some combination of an unrealistically rapid rate of energy decarbonization and nearly immediate reductions in global civilization wealth. Effectively, it appears that civilization may be in a double-bind. If civilization does not collapse quickly this century, then CO2 levels will likely end up exceeding 1000 ppmv; but, if CO2 levels rise by this much, then the risk is that civilization will gradually tend towards collapse.

Determination of the mass-transfer coefficient in liquid phase in a stream-bubble contact device

NASA Astrophysics Data System (ADS)

Dmitriev, A. V.; Dmitrieva, O. S.; Madyshev, I. N.

2016-09-01

One of the most effective energy saving technologies is the improvement of existing heat and mass exchange units. A stream-bubble contact device is designed to enhance the operation efficiency of heat and mass exchange units. The stages of the stream-bubble units that are proposed by the authors for the decarbonization process comprise contact devices with equivalent sizes, whose number is determined by the required performance of a unit. This approach to the structural design eliminates the problems that arise upon the transition from laboratory samples to industrial facilities and makes it possible to design the units of any required performance without a decrease in the effectiveness of mass exchange. To choose the optimal design that provides the maximum effectiveness of the mass-exchange processes in units and their intensification, the change of the mass-transfer coefficient is analyzed with the assumption of a number of parameters. The results of the study of the effect of various structural parameters of a stream-bubble contact device on the mass-transfer coefficient in the liquid phase are given. It is proven that the mass-transfer coefficient increases in the liquid phase, in the first place, with the growth of the level of liquid in the contact element, because the rate of the liquid run-off grows in this case and, consequently, the time of surface renewal is reduced; in the second place, with an increase in the slot diameter in the downpipe, because the jet diameter and, accordingly, their section perimeter and the area of the surface that is immersed in liquid increase; and, in the third place, with an increase in the number of slots in the downpipe, because the area of the surface that is immersed in the liquid of the contact element increases. Thus, in order to increase the mass-transfer coefficient in the liquid phase, it is necessary to design the contact elements with a minimum width and a large number of slots and their increased diameter; in this case, the filling degree of contact elements by the liquid must be maximum.

Nanoscale petrographic and geochemical insights on the origin of the Palaeoproterozoic stromatolitic phosphorites from Aravalli Supergroup, India.

PubMed

Papineau, D; De Gregorio, B; Fearn, S; Kilcoyne, D; McMahon, G; Purohit, R; Fogel, M

2016-01-01

Stromatolites composed of apatite occur in post-Lomagundi-Jatuli successions (late Palaeoproterozoic) and suggest the emergence of novel types of biomineralization at that time. The microscopic and nanoscopic petrology of organic matter in stromatolitic phosphorites might provide insights into the suite of diagenetic processes that formed these types of stromatolites. Correlated geochemical micro-analyses of the organic matter could also yield molecular, elemental and isotopic compositions and thus insights into the role of specific micro-organisms among these communities. Here, we report on the occurrence of nanoscopic disseminated organic matter in the Palaeoproterozoic stromatolitic phosphorite from the Aravalli Supergroup of north-west India. Organic petrography by micro-Raman and Transmission Electron Microscopy demonstrates syngeneity of the organic matter. Total organic carbon contents of these stromatolitic phosphorite columns are between 0.05 and 3.0 wt% and have a large range of δ(13) Corg values with an average of -18.5‰ (1σ = 4.5‰). δ(15) N values of decarbonated rock powders are between -1.2 and +2.7‰. These isotopic compositions point to the important role of biological N2 -fixation and CO2 -fixation by the pentose phosphate pathway consistent with a population of cyanobacteria. Microscopic spheroidal grains of apatite (MSGA) occur in association with calcite microspar in microbial mats from stromatolite columns and with chert in the core of diagenetic apatite rosettes. Organic matter extracted from the stromatolitic phosphorites contains a range of molecular functional group (e.g. carboxylic acid, alcohol, and aliphatic hydrocarbons) as well as nitrile and nitro groups as determined from C- and N-XANES spectra. The presence of organic nitrogen was independently confirmed by a CN(-) peak detected by ToF-SIMS. Nanoscale petrography and geochemistry allow for a refinement of the formation model for the accretion and phototrophic growth of stromatolites. The original microbial biomass is inferred to have been dominated by cyanobacteria, which might be an important contributor of organic matter in shallow-marine phosphorites. © 2015 John Wiley & Sons Ltd.

Characterizing The Microbial Lability And Isotopic (14C, 13C) Signatures Of Marine Organic Matter With A Novel Culture Vessel System

NASA Astrophysics Data System (ADS)

Beaupre, S. R.; Mahmoudi, N.; Pearson, A.

2016-02-01

The rate at which non-living organic matter is respired in the ocean is an unconstrained and important property of the marine carbon cycle. Studies of inherent mineralization rates are complicated by the fact that marine organic matter is a mixture of compounds that vary in reactivity and concentration. While natural radiocarbon ages (14C, half-life = 5730 yr) have served as proxies for lability, they have not been used extensively to characterize that fraction of marine organic matter that is biologically accessible. To address this problem, we developed a novel batch culture system to monitor the time-dependent production rates and isotopic signatures of CO2 released during microbial degradation of natural organic matter. The system simulated a nepheloid layer by maintaining a slurry of decarbonated sediment and minimal media (M9) in a custom 2-liter culture vessel. The natural microbial community was allowed to develop within the sediment, and respired CO2 was continuously sparged from the medium with helium and oxygen, quantified in real time with an infrared gas analyzer, and isolated as a series of contiguous fractions for subsequent isotopic (∆14C, d13C) characterization. Control experiments indicated the accumulation of just 4.5 mg of background carbon per hour of continuous gas flow, which constituted ≤ 10 % of the respired carbon mass in each fraction. Since ∆14C values are conserved during molecular transformations, this low-blank system enables the detection of subtle shifts in the "age" of organic matter respired during the course of a culture experiment. Analyses of sediments from Falmouth, MA revealed both a variable CO2 production rate and an increase in post-bomb ∆14C values during a 10-day incubation. This suggests that the microbial lability of organic matter at this site decreased non-linearly with apparent 14C age, and that the least labile fraction observed was not more than 50 years old. These results underscore the complex relationship between microbial communities, organic matter composition, and its 14C age distribution.

A recipe to create nano-grains on dolomite

NASA Astrophysics Data System (ADS)

Røyne, Anja; Pluymakers, Anne

2017-04-01

Advances in imaging techniques in recent years have allowed for easy microstructure visualization at nano-resolution, and many studies have observed nano-grains in different materials, including rocks. An important example in geological systems is their seemingly ubiquitous occurrence on so-called mirror-like slip surfaces, produced in natural and experimental earthquakes of both carbonate and silicate rocks. It is, however, not yet clear whether these nano-grains can indeed be used as a reliable indicator of seismic slip. Since carbonates are prone to decarbonation at temperatures exceeding 550 - 600 °C, nano-grain formation may be formed due to heating rather than shear. In this study, we have investigated the effect of elevated temperatures on carbonate fault rocks. We used hand-polished mirror-like dolomite protolith, as well as natural fault mirror surfaces, obtained from the Foiana Fault Zone from the Southern Alps in Italy. The samples were heated to 200 to 800 degC in a 5 hour heating cycle, followed by slow cooling ( 12 h) to room temperature. Subsequently, we imaged the samples using SEM and AFM. Nano-grain formation on the surfaces of hand-polished samples starts around 400 ° C, and is pervasive at and above 600 ° C. Fault mirror samples are initially coated with naturally formed nano-grains and only very local patches on these surfaces display obvious morphological changes due to heating. Exposing both types of sample heated to 600 °C to DI water under the AFM shows rapid recrystallization and the formation of a more porous and blade-like crystal layer on the entire surface. This happens both in hand-polished and naturally polished surfaces. Fault mirror samples that have not been heated do not change when exposed to water. We have shown that nano-grains can form as a result of heating without shear, but that samples that have experienced high shear strain have a water- and heat-resistant coating composed of otherwise morphologically indistinguishable nano-grains. These results show that caution is needed when interpreting laboratory and field microstructures, since there is more than one way to cook up a nano-grain.

Petrogenesis of incipient charnockite in the Ikalamavony sub-domain, south-central Madagascar: New insights from phase equilibrium modeling

NASA Astrophysics Data System (ADS)

Endo, Takahiro; Tsunogae, Toshiaki; Santosh, M.; Shaji, E.; Rambeloson, Roger A.

2017-06-01

Incipient charnockites representing granulite formation on a mesoscopic scale occur in the Ambodin Ifandana area of Ikalamavony sub-domain in south-central Madagascar. Here we report new petrological data from these rocks, and discuss the process of granulite formation on the basis of petrography, mineral equilibrium modeling, and fluid inclusion studies. The incipient charnockites occur as brownish patches, lenses, and layers characterized by an assemblage of biotite + orthopyroxene + K-feldspar + plagioclase + quartz + magnetite + ilmenite within host orthopyroxene-free biotite gneiss with an assemblage of biotite + K-feldspar + plagioclase + quartz + magnetite + ilmenite. Lenses and layers of calc-silicate rock (clinopyroxene + garnet + plagioclase + quartz + titanite + calcite) are typically associated with the charnockite. Coarse-grained charnockite occurs along the contact between the layered charnockite and calc-silicate rock. The application of mineral equilibrium modeling on the mineral assemblages in charnockite and biotite gneiss employing the NCKFMASHTO system as well as fluid inclusion study on coarse-grained charnockite defines a P-T range of 8.5-10.5 kbar and 880-900 °C, which is nearly consistent with the inferred P-T condition of the Ikalamavony sub-domain (8.0-10.5 kbar and 820-880 °C). The result of T versus H2O activity (a(H2O)) modeling demonstrates that orthopyroxene-bearing assemblage in charnockite is stable under relatively low a(H2O) condition of 0.42-0.43, which is consistent with the popular models of incipient-charnockite formation related to the lowering of water activity and stabilization of orthopyroxene through dehydration of biotite. The occurrence of calc-silicate rocks adjacent to the charnockite suggests that the CO2-bearing fluid that caused dehydration and incipient-charnockite formation might have been derived through decarbonation of calc-silicate rocks during the initial stage of decompression slightly after the peak metamorphism. The calc-silicate rocks might have also behaved as a cap rock that trapped CO2 infiltrated from an external source. 'CO2-rich fluid ponds' formed beneath calc-silicate layers could have enhanced dehydration of biotite to orthopyroxene, and produced layers of coarse-grained charnockite adjacent to calc-silicate layers.

Enhancing global climate policy ambition towards a 1.5 °C stabilization: a short-term multi-model assessment

NASA Astrophysics Data System (ADS)

Vrontisi, Zoi; Luderer, Gunnar; Saveyn, Bert; Keramidas, Kimon; Reis Lara, Aleluia; Baumstark, Lavinia; Bertram, Christoph; Sytze de Boer, Harmen; Drouet, Laurent; Fragkiadakis, Kostas; Fricko, Oliver; Fujimori, Shinichiro; Guivarch, Celine; Kitous, Alban; Krey, Volker; Kriegler, Elmar; Broin, Eoin Ó.; Paroussos, Leonidas; van Vuuren, Detlef

2018-04-01

The Paris Agreement is a milestone in international climate policy as it establishes a global mitigation framework towards 2030 and sets the ground for a potential 1.5 °C climate stabilization. To provide useful insights for the 2018 UNFCCC Talanoa facilitative dialogue, we use eight state-of-the-art climate-energy-economy models to assess the effectiveness of the Intended Nationally Determined Contributions (INDCs) in meeting high probability 1.5 and 2 °C stabilization goals. We estimate that the implementation of conditional INDCs in 2030 leaves an emissions gap from least cost 2 °C and 1.5 °C pathways for year 2030 equal to 15.6 (9.0–20.3) and 24.6 (18.5–29.0) GtCO2eq respectively. The immediate transition to a more efficient and low-carbon energy system is key to achieving the Paris goals. The decarbonization of the power supply sector delivers half of total CO2 emission reductions in all scenarios, primarily through high penetration of renewables and energy efficiency improvements. In combination with an increased electrification of final energy demand, low-carbon power supply is the main short-term abatement option. We find that the global macroeconomic cost of mitigation efforts does not reduce the 2020–2030 annual GDP growth rates in any model more than 0.1 percentage points in the INDC or 0.3 and 0.5 in the 2 °C and 1.5 °C scenarios respectively even without accounting for potential co-benefits and avoided climate damages. Accordingly, the median GDP reductions across all models in 2030 are 0.4%, 1.2% and 3.3% of reference GDP for each respective scenario. Costs go up with increasing mitigation efforts but a fragmented action, as implied by the INDCs, results in higher costs per unit of abated emissions. On a regional level, the cost distribution is different across scenarios while fossil fuel exporters see the highest GDP reductions in all INDC, 2 °C and 1.5 °C scenarios.

Authigenic Nd isotope record of North Pacific Intermediate Water formation and boundary exchange on the Bering Slope

NASA Astrophysics Data System (ADS)

Jang, Kwangchul; Huh, Youngsook; Han, Yeongcheol

2017-01-01

The Bering Sea is a potential location for the formation of the North Pacific Intermediate Water (NPIW), which drives the global ocean circulation as a counterpart to the North Atlantic Deep Water (NADW). To evaluate the NPIW-NADW seesaw hypothesis, we reconstructed the long-term variation of the bottom water Nd isotopic composition at site U1345 on the Bering Slope by extracting authigenic Fe-Mn oxyhydroxide from bulk sediments. We examined six different extractions in order to ensure that authentic seawater composition is recovered. For Bering Slope sediments whose typical carbonate content is less than 5% (average 2%), the most reliable results are obtained if the decarbonation step is omitted and a low reagent-to-sediment ratio is adopted. The reconstructed authigenic εNd record for the last 520 kyr exhibits large temporal variations depending on whether the NPIW formation or the boundary exchange process is dominant. Periods of radiogenic εNd can be attributed to NPIW formation triggered by brine rejection, as evidenced by the difference in δ18O of benthic foraminifera between sites (Δδ18Obf), high % sea-ice related diatoms, and low abundance of Bulimina aff. Exilis (low-oxygen deep fauna). Diminished supply of unradiogenic Nd from boundary exchange seems to intensify these radiogenic peaks. On the other hand, the unradiogenic εNd intervals can be attributed to stagnant bottom water conditions, as can be deduced from the Δδ18Obf values, low % sea-ice related diatoms, abundant B. aff. Exilis, and laminations. When there is no NPIW formation, the continental margin sediments are exposed to boundary exchange for a longer period of time, leading to release of unradiogenic Nd. The mid-MIS 6 and mid-MIS 5 are exceptions in that NPIW formation occurred yet the εNd compositions are unradiogenic. NPIW formation and cold climate (closed Bering Strait) are not always correlated. Comparison against εNd records of the South Atlantic suggests only an ambiguous NPIW-NADW seesaw for the last 200 kyr.

Generation and Use of Thermal Energy in the U.S. Industrial Sector and Opportunities to Reduce its Carbon Emissions

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

McMillan, Colin A.; Boardman, Richard; McKellar, Michael

The industrial sector was the third-largest source of direct U.S. greenhouse gas (GHG) emissions in 2014 behind electricity generation and transportation and accounted for roughly 20% of total emissions (EPA 2016). The Energy Information Administration (EIA) projects that total U.S. energy consumption will grow to about 108 exajoules (1 EJ = 10 18 J) or 102 quads (1 quad = 10 15 British thermal units) in 2025, with nearly all of the growth coming from the industrial sector (DOE 2015b). Energy consumption in the industrial sector is forecast to increase to 39.5 EJ (37.4 quads)—a 22% increase, exceeding 36% ofmore » total energy consumption in the United States. Therefore, it is imperative that industrial GHG emissions be considered in any strategy intent on achieving deep decarbonization of the energy sector as a whole. It is important to note that unlike the transportation sector and electrical grid, energy use by industry often involves direct conversion of primary energy sources to thermal and electrical energy at the point of consumption. About 52% of U.S. industrial direct GHG emissions are the result of fuel combustion (EPA 2016) to produce hot gases and steam for process heating, process reactions, and process evaporation, concentration, and drying. The heterogeneity and variations in scale of U.S. industry and the complexity of modern industrial firms’ global supply chains are among the sector’s unique challenges to minimizing its GHG emissions. A combination of varied strategies—such as energy efficiency, material efficiency, and switching to low-carbon fuels—can help reduce absolute industrial GHG emissions. This report provides a complement to process-efficiency improvement to consider how clean energy delivery and use by industry could reduce GHG emissions. Specifically, it considers the possibility of replacing fossil-fuel combustion in industry with nuclear (specifically small modular reactors [SMRs]), solar thermal (referred to herein as solar industrial process heat [SIPH]), and geothermal energy sources. The possibility of applying electrical heating and greater use of hydrogen is also considered, although these opportunities are not discussed in as much detail.« less

Computational and experimental studies of iron-bearing carbonates and silicate glasses at lower mantle pressures

NASA Astrophysics Data System (ADS)

Solomatova, N. V.; Jackson, J. M.; Asimow, P. D.; Sturhahn, W.; Rossman, G. R.; Roskosz, M.

2017-12-01

Decomposition of carbonates may be responsible for creating silicate melts within the lower mantle by lowering the melting temperature of surrounding rock. Identifying and characterizing the stability of carbonates is therefore a necessary step towards understanding the transport of carbon in Earth's interior. Dolomite is one of the major mineral forms in which carbon is subducted into the Earth's mantle. Although iron-free dolomite is expected to break down upon compression, high-pressure polymorphs of iron-bearing dolomite may resist decomposition. Using a genetic algorithm that predicts crystal structures, we found a monoclinic phase with space group C2/c that has a lower energy than all previously reported dolomite structures at pressures above 15 GPa, where the substitution of iron for magnesium stabilizes monoclinic dolomite at certain pressures of the lower mantle. Thus, an iron-bearing dolomite polymorph may be an important carbon carrier in regions of Earth's lower mantle. The depth at which carbonates will decompose is dependent on the age, temperature and density of subducting slabs. Decarbonation reactions may lower the melting temperature of surrounding rocks to produce silicate melts. In regions of the mantle where silicate melts may exist, it is important to understand the physical properties and dynamic behavior of the melts because they affect the chemical and thermal evolution of its interior. Composition, degree of polymerization, and iron's spin state affect such properties. The behavior of iron in silicate melts is poorly understood but, in some cases, may be approximated by iron-bearing glasses. We measured the hyperfine parameters of iron-bearing rhyolitic and basaltic glasses up to 120 GPa and 100 GPa, respectively, in a neon pressure medium using time-domain synchrotron Mössbauer spectroscopy. The spectra for rhyolitic and basaltic glasses are well explained by three high-spin Fe2+-like sites with distinct quadrupole splittings, reflecting the influence of evolving coordination environments with pressure. With the assumption that coordination environments in silicate glasses may serve as a good indicator for those in a melt, this study suggests that ferrous iron in chemically-complex silicate melts likely exists in a high-spin state throughout most of Earth's mantle.

Carbonation of Subduction Interface Ultramafic Rocks and Implications for Deep Carbon Cycling: Evidence from Hybrid Serpentinite-Marble in the Voltri Massif, Italy

NASA Astrophysics Data System (ADS)

Scambelluri, M.; Bebout, G. E.; Gilio, M.; Belmonte, D.; Campomenosi, N.; Crispini, L.

2015-12-01

Release of COH fluids from hydrous minerals and carbonates influences element recycling and magmatism at subduction zones. Contradictory interpretations exist regarding the retention/storage of C in subducting plates and in the forearc to subarc mantle. Multiple lines of evidence indicate mobility of C in forearcs; however, the magnitude of this loss is highly uncertain[1-5]. A poorly constrained fraction of the 40-115 Mt/y of C initially subducted is released into fluids (e.g., by decarbonation, carbonate dissolution), and 18-43 Mt/y is returned at arc volcanoes[2-5, refs. therein]. The imbalance could reflect subduction into the deeper mantle or forearc/subarc storage[4-7]. We examine the fate of C in slab/interface ultramafic rocks, and by analogy serpentinized mantle wedge, via study of fluid-rock evolution of marble and variably carbonated serpentinite (Ligurian Alps). Based on petrography, and major/trace element and C and O isotope compositions, we demonstrate that serpentinite dehydration at 2-2.5 GPa, 550°C released aqueous fluids triggering breakdown of dolomite in nearby marbles, thus releasing C into fluids. Carbonate + olivine veins document flow of COH fluids; interaction of these COH fluids with serpentinite led to formation of high-pressure carbonated ultramafic-rock domains, thus resulting in retention of C in some rocks at an ancient subduction interface. We stress that lithologically complex interfaces could contain sites of both C release and C addition, further confounding estimates of net C loss at forearc and subarc depths [cf 4,5]. Sites of C retention, also including carbonate veins and graphite as reduced carbonate[7], could influence the transfer of slab C to at least the depths beneath volcanic fronts. 1. Poli S et al. 2009 EPSL; 2. Ague and Nicolescu 2014 Nat Geosci; 3. Cook-Collars et al. 2014 Chem Geol; 4. Collins et al. 2015 Chem Geol; 5. Kelemen and Manning 2015 PNAS; 6. Sapienza et al. 2009 CMP; 7 Galvez et al. 2013 Nat Geosci

Applying Transmission Kikuchi Diffraction (TKD) to Understand Nanogranular Fault Rock Materials

NASA Astrophysics Data System (ADS)

Smith, S. A. F.; Demurtas, M.; Prior, D. J.; Di Toro, G.

2017-12-01

Nanoparticles (<< 1 µm) form in the localized slip zones of natural and experimental faults, but their origin (e.g. seismic vs. aseismic slip) and mechanical behaviour is still debated. Understanding the deformation processes that produce nanoparticles in faults requires an understanding of grain sizes, shapes and crystallographic orientations at higher spatial resolution than is currently possible using standard EBSD techniques. Transmission Kikuchi Diffraction (TKD) in the SEM is a technique that allows to overcome this spatial resolution issue by performing orientation mapping in a commercial EBSD system on electron transparent foils with resolutions that can be below 10 nm. Therefore, the potential of TKD to understand deformation processes in nanoparticles is very high. We present results of TKD analysis performed on mixed calcite-dolomite gouges deformed in a rotary-shear apparatus at slip rates ranging from sub-seismic to co-seismic (30 µm/s to 1 m/s). Samples for TKD were prepared by argon ion slicing, a method that yields relatively large (104 µm2) electron transparent areas, as well as standard argon ion milling. Coupled TKD-EDS analysis allows quantification of elemental contents at a scale of tens of nanometers. Preliminary results show that at a slip velocity of 1 m/s, the localized slip zone that forms in the gouges during shearing is composed of recrystallized grains of calcite and Mg-calcite (the latter being a decarbonation product of dolomite) with an average grain size of c. 300 nm. Individual grains are characterized by relatively straight boundaries, and many triple and quadruple grain junctions are present. The nanogranular aggregates show a polygonised texture with absence of clear porosity and shape preferred orientation. Orientation data show a random distribution of the calcite c-axes. Further investigation will help to obtain new insights into the deformation mechanisms active during seismic faulting in carbonate-bearing faults. The integration of grain size, grain shape and crystallographic information into flow laws will help to describe and predict the rheological behaviour of carbonate faults during seismic sliding.

Opportunities and trade-offs of biomass based negative emissions within planetary boundaries

NASA Astrophysics Data System (ADS)

Heck, Vera; Gerten, Dieter; Lucht, Wolfgang

2017-04-01

The Paris Agreement requires "a balance between anthropogenic emissions by sources and removals by sinks of greenhouse gases in the second half of the century" (UNFCCC, 2015). Without a full decarbonization of the energy and land use sector until the second half of this century, negative emission technologies (NETs) are required to achieve net zero greenhouse gas emissions. Integrated assessment studies indicate that bioenergy with carbon capture and storage (BECCS), a land based NET, has the potential to contribute substantially to balancing anthropogenic fossil fuel emissions. However, significant negative emission potentials from BECCS require substantial biomass potentials, which can only be achieved by intensively managed (fertilized and irrigated) large-scale biomass plantations. Additional to direct trade-offs of land and water availability, the implementation of large-scale biomass plantations implies major restructuring of the land surface on top of existing land use and would be accompanied by indirect trade-offs such as changes in moisture and energy fluxes. In the context of the planetary boundaries framework as proposed by Rockström et al. (2009), BECCS might contribute to reduce the transgression of the planetary boundary (PB) for climate change, but would most likely steer the Earth system closer to the PB for freshwater use and lead to further transgression of the PBs for land system change, biosphere integrity and biogeochemical flows. This presentation will investigate the opportunities of second generation biomass potentials within the safe operating space for humanity and highlight the multidimensional trade-offs between biomass potentials for BECCS in relation to the PBs. Scenarios of land availability for biomass plantations and land based carbon sequestration were developed with a spatially explicit multi-criterial optimization framework, considering the precautionary need to stay within the safe operating space vis-à-vis the need to sustain food supply. References: UNFCCC. Adoption of the Paris Agreement, FCCC/CP/2015/L.9/Rev1, United Nations Framework Convention on Climate Change (2015). J. Rockström et al., A safe operating space for humanity. Nature 461 (7263), 472-475 (2009) Without a full ecarbonization of the energy and land use sector, nes are required to balance sinks and sources according

Time-resolved remote Raman study of minerals under supercritical CO2 and high temperatures relevant to Venus exploration.

PubMed

Sharma, Shiv K; Misra, Anupam K; Clegg, Samuel M; Barefield, James E; Wiens, Roger C; Acosta, Tayro

2010-07-13

We report time-resolved (TR) remote Raman spectra of minerals under supercritical CO(2) (approx. 95 atm pressure and 423 K) and under atmospheric pressure and high temperature up to 1003 K at distances of 1.5 and 9 m, respectively. The TR Raman spectra of hydrous and anhydrous sulphates, carbonate and silicate minerals (e.g. talc, olivine, pyroxenes and feldspars) under supercritical CO(2) (approx. 95 atm pressure and 423 K) clearly show the well-defined Raman fingerprints of each mineral along with the Fermi resonance doublet of CO(2). Besides the CO(2) doublet and the effect of the viewing window, the main differences in the Raman spectra under Venus conditions are the phase transitions, the dehydration and decarbonation of various minerals, along with a slight shift in the peak positions and an increase in line-widths. The dehydration of melanterite (FeSO(4).7H(2)O) at 423 K under approximately 95 atm CO(2) is detected by the presence of the Raman fingerprints of rozenite (FeSO(4).4H(2)O) in the spectrum. Similarly, the high-temperature Raman spectra under ambient pressure of gypsum (CaSO(4).2H(2)O) and talc (Mg(3)Si(4)O(10)(OH)(2)) indicate that gypsum dehydrates at 518 K, but talc remains stable up to 1003 K. Partial dissociation of dolomite (CaMg(CO(3))(2)) is observed at 973 K. The TR remote Raman spectra of olivine, alpha-spodumene (LiAlSi(2)O(6)) and clino-enstatite (MgSiO(3)) pyroxenes and of albite (NaAlSi(3)O(8)) and microcline (KAlSi(3)O(8)) feldspars at high temperatures also show that the Raman lines remain sharp and well defined in the high-temperature spectra. The results of this study show that TR remote Raman spectroscopy could be a potential tool for exploring the surface mineralogy of Venus during both daytime and nighttime at short and long distances.

Ionogel Electrolytes through Sol-Gel Processing

NASA Astrophysics Data System (ADS)

Horowitz, Ariel I.

Electrical energy needs have intensified due to the ubiquity of personal electronics, the decarbonization of energy services through electrification, and the use of intermittent renewable energy sources. Despite developments in mechanical and thermal methods, electrochemical technologies are the most convenient and effective means of storing electrical energy. These technologies include both electrochemical cells, commonly called batteries, and electrochemical double-layer capacitors, or "supercapacitors", which store energy electrostatically. Both device types require an ion-conducting electrolyte. Current devices use solutions of complex salts in organic solvents, leading to both toxicity and flammability concerns. These drawbacks can be avoided by replacing conventional electrolytes with room-temperature molten salts, known as ionic liquids (ILs). ILs are non-volatile, non-flammable, and offer high conductivity and good electrochemical stability. Device mass can be reduced by combining ILs with a solid scaffold material to form an "ionogel," further improving performance metrics. In this work, sol-gel chemistry is explored as a means of forming ionogel electrolytes. Sol-gel chemistry is a solution-based, industrially-relevant, well-studied technique by which solids such as silica can be formed in situ. Previous works used a simple acid-catalyzed sol-gel reaction to create brittle, glassy ionogels. Here, both the range of products that can be accomplished through sol-gel processing and the understanding of interactions between ILs and the sol-gel reaction network are greatly expanded. This work introduces novel ionogel materials, including soft and compliant silica-supported ionogels and PDMS-supported ionogels. The impacts of the reactive formulation, IL identity, and casting time are detailed. It is demonstrated that variations in formulation can lead to rapid gelation and open pore structures in the silica scaffold or slow gelation and more dense silica morphologies. The IL identity is shown to have an impact on the apparent strength of the acid catalyst, leading to significant shifts in gelation time. Delayed casting is proven to be an optimal technique for avoiding pore blockage when combining ionogels with high surface area electrodes for supercapacitor applications. Finally, a simple recycling process is proposed, establishing that ILs can be easily reclaimed from silica-supported ionogels and reused, thereby validating the reputation of ILs as "green" materials.

Phase change of hydromagnesite, Mg5(CO3)4(OH)2 4H2O by thermal decomposition

NASA Astrophysics Data System (ADS)

Yamamoto, G. I.; Kyono, A.; Tamura, T.

2017-12-01

In recent years, the global warming is the most important environment problem, and thus attempts of CO2 geological storage have been made to remove carbon dioxide from the atmosphere all over the world (XUE and Nakao 2008). Regarding mineral CO2 sequestration, CO2 is chemically stored in solid carbonates by carbonation of minerals. Magnesium and calcium carbonates have long been known as a good CO2 storage. Hydrous magnesium carbonates can be, however, considered as much better candidates for CO2 storage because they precipitate easily from aqueous solutions. The typical hydrous magnesium carbonates are nesquehonite, MgCO3 3H2O and hydromagnesite, Mg5(CO3)4(OH)2 4H2O. Concerning their thermal properties, the former has been studied in detail, whereas, the latter is not enough. In this study, we performed in-site high-temperature X-ray diffraction (XRD) and thermogravimetric and differential thermal (TG-DTA) analyses to reveal the phase change of hydromagnesite at high temperature. The high-temperature XRD and TG-DTA were measured up to 320 oC and 550 oC, respectively. The results of in-site high-temperature XRD showed that, no significant change was observed up to 170 oC. With increasing temperature, the intensities of started to decrease at 200 oC, and all peaks disappeared at 290 oC. Above the temperature of the decomposition a few peaks corresponding to periclase appeared. The results of TG-DTA clearly showed that there were two weight loss steps in the temperature range of 200 to 340 oC and 340 to 500 oC, which correspond to the dehydration and decarbonation of hydromagnesite, respectively. These weight losses were accompanied by the endothermic maxima in the DTA. The dihydroxylation of hydromagnesite is spread over the two steps. Therefore, hydromagnesite decomposes into periclase, carbon dioxide, and water without passing through magnesite around 300 oC as following reaction: Mg5(CO3)4(OH)2 4H2O → 5MgO + 4CO2 + 5H2O.

Tectonic Mechanism for the Mid-Cretaceous - Early Paleogene Intraplate Magmatism from the Gulf of Mexico to Northwestern Canada

NASA Astrophysics Data System (ADS)

Liu, Y.; Murphy, M. A.; Snow, J. E.; van Wijk, J.; Cannon, J. M.; Parsons, C.

2017-12-01

Tectonic mechanisms have remained controversial for a number of intraplate igneous suites of mid-Cretaceous - early Paleogene age across North America. They span the northern Gulf of Mexico (GoM), through Arkansas and Kansas in the US, to Saskatchewan and Northwestern Territories in Canada, resembling a belt that is located 1000+ km inboard from, and aligned sub-parallel to, the western margin of North America. The northern GoM magmatism is characterized by lamproites, carbonatites, nephelinites, with other alkaline rocks, whereas the rest igneous provinces are dominated by kimberlites. Their geochemical signatures, in general, point to a sub-lithospheric mantle origin. Hypotheses that explain the tectonic origin of these magmatic rocks include: (1) hotspots and mantle plumes, (2) edge-driven convection, (3) lithospheric reactivation, and (4) low-angle subduction. Evaluation based on our integration of published geological and geophysical data shows that contradictions exist in each model between observations and predictions. To explain this plate-scale phenomenon, we propose that the Farallon slab may have stagnated within or around the mantle transition zone during the Early Cretaceous, with its leading edge reaching ca. 1600 km inland beneath the North American plate. Dehydration and decarbonation of the slab produces sporadic, dense, low-degree partial melts at the mantle transition zone depths. As the slab descends into the lower mantle, Rayleigh-Taylor instabilities are induced at slab edges, causing passive upwelling that brings alkali-rich carbonate silicate melts to the base of the overriding plate. Subsequently, the North American lithosphere with varying thicknesses, discontinuities, and compositions interacts with the rising partial melts, generating a spectrum of igneous rocks. Fragments of the once-stagnated slab may still be detectable in the lower mantle beneath eastern US in seismic tomography models. This study highlights a profound plate-scale relationship between the intraplate magmatism and the subduction factory down to the transition zone depth, and anticipates future discoveries of kimberlites, potentially diamondiferous, in the mid-west of the North American continent.

Small amounts of CO2-H2O-rich melt in the lithosphere-asthenosphere.

NASA Astrophysics Data System (ADS)

Gaillard, Fabrice; Sifre, David; Hashim, Leila; Hier-Majumder, Saswata

2014-05-01

A low viscosity layer at the Lithosphere-Asthenosphere Boundary (LAB) is certainly a requirement for plate tectonics but the nature of the rocks presents in this boundary remains controversial. The seismic low velocities and the high electrical conductivities of the LAB are attributed either to sub-solidus water-related defects in olivine minerals or to a few volume percents of partial melt but these two interpretations have shortcomings: (1) The amount of H2O stored in olivine is not expected to be high enough due to several mineralogical processes that have been so far ignored, including partial melting; (2) elevated melt volume fractions are impeded by the too cold temperatures prevailing in the LAB and by the high melt mobility that can lead to gravitational segregation. All this has long been discussed (30 years ago) when petrologists have defined the petrological LAB as the region of the upper mantle impregnated by incipient melts; that is small amounts of melt caused by small amount of CO2 and H2O. We show here that this incipient melting is a melting regime that is allowed in the entire P-T-fO2 region of the LVZ. The top of the oceanic LVZ (LAB) is best explained by a melt freezing layer due to a decarbonation reaction, whereas the bottom of the LVZ matches the depth at which redox melting defines the lower boundary of stability of incipient melts. Based on new laboratory measurements, we show here that incipient melts must be the cause of the high electrical conductivities in the oceanic LVZ. Considering relevant mantle abundances of H2O and CO2 and their effect on the petrology of incipient melting, we calculated conductivity profiles across the LAB for various ages. Several electrical discontinuities are predicted and match geophysical observations in a consistent petrological and geochemical framework. Incipient melts most likely trigger both the seismic low velocities and the high electrical conductivities in the upper part of the asthenosphere.

Effectiveness of carbon dioxide removal in lowering atmospheric CO2 and reversing global warming in the context of 1.5 degrees

NASA Astrophysics Data System (ADS)

Zickfeld, K.; Azevedo, D.

2017-12-01

The majority of emissions scenarios that limit warming to 2°C, and nearly all emission scenarios that do not exceed 1.5°C warming by the year 2100 require artificial removal of CO2 from the atmosphere. Carbon dioxide removal (CDR) technologies in these scenarios are required to offset emissions from sectors that are difficult or costly to decarbonize and to generate global `net negative' emissions, allowing to compensate for earlier emissions and to meet long-term climate stabilization targets after overshoot. Only a few studies have explored the Earth system response to CDR and large uncertainties exist regarding the effect of CDR on the carbon cycle and its effectiveness in reversing climate impacts after overshoot. Here we explore the effectiveness of CDR in lowering atmospheric CO2 ("carbon cycle effectiveness") and cool global climate ("cooling effectiveness"). We force the University of Victoria Earth System Climate Model, a model of intermediate complexity, with a set of negative CO2 emissions pulses of different magnitude and applied from different background atmospheric CO2 concentrations. We find the carbon cycle effectiveness of CDR - defined as the change in atmospheric CO2 per unit CO2 removed - decreases with the amount of CO2 removed from the atmosphere and increases at higher background CO2 concentrations from which CDR is applied due to nonlinear responses of carbon sinks to CO2 and climate. The cooling effectiveness - defined as the change in global mean surface air temperature per unit CO2 removed - on the other hand, is largely insensitive to the amount of CO2 removed, but decreases if CDR is applied at higher atmospheric CO2 concentrations, due to the logarithmic relationship between atmospheric CO2 and radiative forcing. Based on our results we conclude that CDR is more effective in restoring a lower atmospheric CO2 concentration and reversing impacts directly linked to CO2 at lower levels of overshoot. CDR's effectiveness in restoring a cooler climate, on the other hand, is largely insensitive to the level of overshoot.

A Fluid-driven Earthquake Cycle, Omori's Law, and Fluid-driven Aftershocks

NASA Astrophysics Data System (ADS)

Miller, S. A.

2015-12-01

Few models exist that predict the Omori's Law of aftershock rate decay, with rate-state friction the only physically-based model. ETAS is a probabilistic model of cascading failures, and is sometimes used to infer rate-state frictional properties. However, the (perhaps dominant) role of fluids in the earthquake process is being increasingly realised, so a fluid-based physical model for Omori's Law should be available. In this talk, I present an hypothesis for a fluid-driven earthquake cycle where dehydration and decarbonization at depth provides continuous sources of buoyant high pressure fluids that must eventually make their way back to the surface. The natural pathway for fluid escape is along plate boundaries, where in the ductile regime high pressure fluids likely play an integral role in episodic tremor and slow slip earthquakes. At shallower levels, high pressure fluids pool at the base of seismogenic zones, with the reservoir expanding in scale through the earthquake cycle. Late in the cycle, these fluids can invade and degrade the strength of the brittle crust and contribute to earthquake nucleation. The mainshock opens permeable networks that provide escape pathways for high pressure fluids and generate aftershocks along these flow paths, while creating new pathways by the aftershocks themselves. Thermally activated precipitation then seals up these pathways, returning the system to a low-permeability environment and effective seal during the subsequent tectonic stress buildup. I find that the multiplicative effect of an exponential dependence of permeability on the effective normal stress coupled with an Arrhenius-type, thermally activated exponential reduction in permeability results in Omori's Law. I simulate this scenario using a very simple model that combines non-linear diffusion and a step-wise increase in permeability when a Mohr Coulomb failure condition is met, and allow permeability to decrease as an exponential function in time. I show very strong spatial correlations of the simulated evolved permeability and fluid pressure field with aftershock hypocenters from this 1992 Landers and 1994 Northridge aftershock sequences, and reproduce the observed aftershock decay rates. Controls on the decay rates (p-value) will also be discussed.

Chemistry and Isotopic Composition of Slab-Derived Fluids from Serpentine Mud Volcanoes in the Mariana Forearc

NASA Astrophysics Data System (ADS)

Ryan, J. G.; Menzies, C. D.; Teagle, D. A. H.; Price, R. E.; Sissmann, O.; Wheat, C. G.; Boyce, A.

2017-12-01

Geological processes at subduction zone margins control seismicity, plutonism/ volcanism, and geochemical cycling between the oceans, crust, and mantle. The down-going plate experiences dehydration, and associated metamorphism alters the physical properties of the plate interface and mantle wedge. The Mariana convergent margin is non-accretionary, and serpentinite mud volcanoes in the pervasively faulted forearc mark loci of fluid and material egress from the subducting slab and forearc mantle. IODP Expedition 366 drilled into three serpentinite mud volcanoes: Yinazao (13 km depth-to-slab); Fantangisña (14 km) and Asùt Tesoru (18 km), allowing comparison with the previously drilled South Chamorro (18 km) and Conical (19 km) Seamounts. We use the changes in chemistry and isotopic composition of porefluids between seamounts to trace the evolution of the downgoing slab and water-rock interactions in the overlying mantle wedge. Boron isotopes allow investigation of the processes governing prograde metamorphism in the downgoing slab, and combined with O, D/H and Sr isotopes are used to assess the balance between seawater and dehydration fluids during mantle wedge serpentinization. The shallowest depth-to-slab seamounts, Yinazao and Fantangisña, are associated with Ca and Sr-enriched, but otherwise solute poor, low alkalinity fluids of pH 11. In contrast, the Asùt Tesoru seamount fluids are markedly higher in Na and Cl, as well as in tracers like B and K, which are associated with the breakdown of slab sheet silicate phases, and are depleted in Ca and Sr compared to seawater. Higher DIC at this site is attributed to slab carbonate decomposition. The elevated pH ( 12.5) is likely due to Fe2+ oxidation, producing H2 and OH- during serpentinization. Asùt Tesoru porefluids are similar to those studied at South Charmorro and Conical Seamounts that have similar depths to slab, although those sites have distinctly lower Na and Cl, but 3-4 times higher B concentrations. These changes between sites reflect metamorphic prograde reactions on the downgoing plate with increasing depth (P-T°). At shallow depths sediment compaction and opal CT dehydration dominate; intermediate depths are characterised by clay diagenesis and desorbed water release; and at greater depths decarbonation and clay decomposition are dominant.

A CLEAN Network Initiative - Accelerating Transition to Post Carbon and Resilient Communities through Education and Engagement

NASA Astrophysics Data System (ADS)

Ledley, T. S.; Niepold, F., III; Bozuwa, J.; Davis, A.; Fraser, J.; Kretser, J.; Poppleton, K. L. I.; Qusba, L.; Ruggiero, K.; Spitzer, W.; Stylinski, C.

2016-12-01

The Climate Literacy and Energy Awareness Network (CLEAN) was formed in 2008 to help climate and energy literacy stakeholders implement the Climate and Energy Literacy Essential Principles to enable effective and responsible decisions with regard to actions that may affect climate. The ongoing conversations of the CLEAN Network have cultivated a culture of shared resources and expertise and allowed for the development of collective impact strategies. However, it has become clear that to accelerate and scale change, effective mitigation, adaptation, and resilience strategies must be developed by a diverse network of stakeholders at the community level to deal with the local impacts of climate change and move toward decarbonized and resilient economies. A group of CLEAN Network members, experienced in establishing effective networks and representing mature climate change education programs, came together to discuss at the community level 1) how we can collectively enable larger scale efforts to 2) develop effective strategies, 3) identify gaps in the system that limit action, and 4) coordinate possible vectors for interceding to advance community level decisions related to climate. We will describe our Theory of Change, based on both the power of communities and increasing climate literacy as a key requirement for sustained progress on the crisis climate change presents. From our Theory of Change, we have begun to outline a national monitoring strategy that can provide communities a measured way to understand their local readiness to respond to the impacts of climate change and understand the magnitude of those impacts in relation to their political and ecological economies. The scale would help describe the robustness of their programs and partnerships to address those impacts, the political climate for working in advance of pending change, and the degree of citizen engagement in resilience planning and action. The goal is to provide a common tool equivalent to GDP that communities could use to see their strengths and leverage points, and where they have the local resources to build solutions or co-develop solutions with others. Though this new tool, communities may be better able to focus on mitigation, adaptation, and the building of resilience that will put into practice the identified Theory of Change.

Aluminum Carbothermic Technology

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

Bruno, Marshall J.

2005-03-31

This report documents the non-proprietary research and development conducted on the Aluminum Carbothermic Technology (ACT) project from contract inception on July 01, 2000 to termination on December 31, 2004. The objectives of the program were to demonstrate the technical and economic feasibility of a new carbothermic process for producing commercial grade aluminum, designated as the ''Advanced Reactor Process'' (ARP). The scope of the program ranged from fundamental research through small scale laboratory experiments (65 kW power input) to larger scale test modules at up to 1600 kW power input. The tasks included work on four components of the process, Stagesmore » 1 and 2 of the reactor, vapor recovery and metal alloy decarbonization; development of computer models; and economic analyses of capital and operating costs. Justification for developing a new, carbothermic route to aluminum production is defined by the potential benefits in reduced energy, lower costs and more favorable environmental characteristics than the conventional Hall-Heroult process presently used by the industry. The estimated metrics for these advantages include energy rates at approximately 10 kWh/kg Al (versus over 13 kWh/kg Al for Hall-Heroult), capital costs as low as $1250 per MTY (versus 4,000 per MTY for Hall-Heroult), operating cost reductions of over 10%, and up to 37% reduction in CO2 emissions for fossil-fuel power plants. Realization of these benefits would be critical to sustaining the US aluminum industries position as a global leader in primary aluminum production. One very attractive incentive for ARP is its perceived ability to cost effectively produce metal over a range of smelter sizes, not feasible for Hall-Heroult plants which must be large, 240,000 TPY or more, to be economical. Lower capacity stand alone carbothermic smelters could be utilized to supply molten metal at fabrication facilities similar to the mini-mill concept employed by the steel industry. Major accomplishments for the program include definition of the system thermo-chemistry, demonstration of reactor stage 1, development of reactor stage 2 critical components in a 500 kW module, experimental determination of the vapor recovery reactor fundamentals, detailed design and installation of an advanced stage 1/vapor recovery reactor, feasibility of efficient separation of Al-C metal alloy product, updated capital and operating cost estimates, and development of computer models for all steps of the Advanced Reactor Process.« less

Partitioning of Large-ion Lithophile Elements Between Aqueous Fluids and Melts: Role of Saline Fluids in Sub-arc Mantle

NASA Astrophysics Data System (ADS)

Kawamoto, T.; Mibe, K.

2014-12-01

Chemical fractionation of slab-derived supercritical fluids can play an important role in elemental transfer from subducting slab to the mantle wedge and arc magmatism [1]. Recent findings of saline fluids from sub-arc mantle peridotite indicate that aqueous fluids in mantle wedge can contain 3.7 wt% NaCl in Ichinomageta, Northeast Japan arc [2] to 5.1 wt% NaCl in Pinatubo, Luzon arc [3]. It is, therefore, important to determine the effect of Cl on the trace element partitioning between aqueous fluids and melts. Synchrotron radiation X-ray fluorescence (XRF) analysis is conducted to know Rb, Sr, and Pb partitioning between aqueous fluids and melts [4]. There is a positive correlation between partition coefficients and pressure, as well as salinity. Two slab-derived components, melt and fluid components, are suggested to explain trace element characteristics of arc-basalts in the Mariana arc [5]. The fluid component is characterized by enrichment of alkali and alkali earth elements. Such features can be explained if the fluid component is a saline fluid, because alkali earth elements and Pb are much less mobile with Cl-free fluids than Cl-rich fluids [4]. We suggest that slab-derived components have compositional features consistent with a saline fluid and a melt, which can be formed through a separation of a slab-derived supercritical fluid [1]. Slab derived supercritical fluids contain Cl, and aqueous fluids inherit much of the Cl and some of the large-ion lithophile elements. [1] Kawamoto et al. 2012, Separation of supercritical slab-fluids to form aqueous fluid and melt components in subduction zone magmatism. PNAS, pnas.org/content/109/46/18695 [2] Kumagai et al. Evolution of carbon dioxide bearing saline fluids in the mantle wedge beneath the Northeast Japan arc, CMP [3] Kawamoto et al. 2013, Mantle wedge infiltrated with saline fluids from dehydration and decarbonation of subducting slab. PNAS, pnas.org/content/110/24/9663 [4] Kawamoto et al. 2014, Large ion lithophile elements delivered by saline fluids to the sub-arc mantle, EPS, earth-planets-space.com/content/66/1/61 [5] Pearce et al. 2005, Geochemical mapping of the Mariana arc-basin system: Implications for the nature and distribution of subduction components. G-cubed, onlinelibrary.wiley.com/doi/10.1029/2004GC000895/full

Speciation of High-Pressure Carbon-Saturated COH Fluids at Buffered fO2 Conditions: An Experimental Approach

NASA Astrophysics Data System (ADS)

Tumiati, S.; Tiraboschi, C.; Recchia, S.; Poli, S.

2014-12-01

The quantitative assessment of species in COH fluids is crucial in modelling mantle processes. For instance, H2O/CO2 ratio in the fluid phase influences the location of the solidus and of carbonation/decarbonation reactions in peridotitic systems . In the scientific literature, the speciation of COH fluids has been generally assumed on the basis of thermodynamic calculations using equations of state of simple H2O-non-polar gas systems (e.g., H2O-CO2-CH4). Only few authors dealt with the experimental determination of high-pressure COH fluid species at different conditions, using diverse experimental and analytical approaches (e.g., piston cylinder+capsule-piercing+gas-chromatography/mass-spectrometry; cold-seal+silica glass capsules+Raman). We performed experiments on COH fluids using a capsule-piercing device coupled with a quadrupole mass spectrometry. This type of analyzer ensures superior performances in terms of selectivity of molecules to be detected, high acquisition rates and extended linear response range. Experiments were carried out in a rocking piston cylinder apparatus at pressure of 1 GPa and temperatures from 800 to 900°C. Carbon-saturated fluids were generated through the addition of oxalic acid dihydrate and graphite. Single/double capsules and different packing materials (BN and MgO) were used to evaluate the divergence from the thermodynamic speciation model. Moreover, to assess the effect of solutes on COH fluid speciation we also performed a set of experiments adding synthetic forsterite to the charge. To determine the speciation we assembled a capsule-piercing device that allows to puncture the capsule in a gas-tight vessel at 80°C. The extraction Teflon vessel is composed of a base part, where the capsule is allocated on a steel support, and a top part where a steel drill is mounted. To release the quenched fluids from the capsule, the base part of vessel is hand-tighten to the top part, allowing the steel pointer to pierce the capsule. The evolved gases are then convoyed to a quadrupole mass spectrometer through a heated line to avoid the condensation of water. Our results suggest that fluid speciation can diverge considerably compared to the thermodynamic model depending on the experimental strategies adopted and on the presence of solutes in complex COH systems.

A laser GC-IRMS technique for in situ stable isotope analyses of carbonates and phosphates

NASA Astrophysics Data System (ADS)

Sharp, Z. D.; Cerling, T. E.

1996-08-01

A technique is described whereby in situ carbon and oxygen isotope analyses of carbonates and organic phosphates can be made with the use of a CO 2 laser. The CO 2 gas generated by thermal decarbonation from the laser is entrained in a helium carrier gas, passes through a chromatographic column (GC), and is admitted directly into the isotope ratio mass spectrometer (IRMS). No vacuum systems, pumps, or cryogenic traps are used. All carbonates and biogenic phosphates can be analyzed, no special sample preparation is required and analyses can be made every 3 minutes. The use of a helium carrier gas allows for extremely small samples to be analyzed and the GC column effectively separates CO 2 from any other potential contaminating gases (e.g., SO 2 which is a particular problem in organic apatite). The average reproducibility of calcite, dolomite, magnesite, rhodochrosite, siderite, and smithsonite (ZnCO 3) is 0.29‰ for oxygen and 0.1‰ for carbon (1σ); the most "homogeneous" samples are reproducible to better than 0.1‰ for carbon and 0.2‰ for oxygen. The difference between the laser and conventional values for carbon isotope ratios [Δ 13C (laser-conv)] is 0.05 ± 0.30‰ for all carbonates (excluding siderite). The Δ 18O(laser-conv) value varies from carbonate to carbonate and may be related to the electronegativities of the cations, grain size (or crystallinity), formation of CO and O 2, and reaction with included organic matter. For calcite and rhodochrosite, the Δ 18O(laser-conv) value is 0.3 ± 0.4‰; for siderite, magnesite, and dolomite, the Δ 18O(laser-conv) value is 1.7 ± 0.3‰. The δ 13C values of tooth enamel are the same as those obtained by conventional acid digestion. The laser δ 18O values are equal to the δ 18O values of the phosphate, and approx. 7‰ lighter than the "carbonate" oxygen. The carbonate group in the apatite (equiv. 7.6% oxygen) exchanges with the (PO 4=)-bound oxygen to produce CO 2 with a δ 18O equal to the phosphate oxygen. The laser technique provides a rapid alternative to the difficult phosphate extraction technique for oxygen isotope measurements in tooth enamel.

The economics and environmental impacts of large-scale wind power in a carbon constrained world

NASA Astrophysics Data System (ADS)

Decarolis, Joseph Frank

Serious climate change mitigation aimed at stabilizing atmospheric concentrations of CO2 will require a radical shift to a decarbonized energy supply. The electric power sector will be a primary target for deep reductions in CO2 emissions because electric power plants are among the largest and most manageable point sources of emissions. With respect to new capacity, wind power is currently one of the most inexpensive ways to produce electricity without CO2 emissions and it may have a significant role to play in a carbon constrained world. Yet most research in the wind industry remains focused on near term issues, while energy system models that focus on century-long time horizons undervalue wind by imposing exogenous limits on growth. This thesis fills a critical gap in the literature by taking a closer look at the cost and environmental impacts of large-scale wind. Estimates of the average cost of wind generation---now roughly 4¢/kWh---do not address the cons arising from the spatial distribution and intermittency of wind. This thesis develops a theoretical framework for assessing the intermittency cost of wind. In addition, an economic characterization of a wind system is provided in which long-distance electricity transmission, storage, and gas turbines are used to supplement variable wind power output to meet a time-varying load. With somewhat optimistic assumptions about the cost of wind turbines, the use of wind to serve 50% of demand adds ˜1--2¢/kWh to the cost of electricity, a cost comparable to that of other large-scale low carbon technologies. This thesis also explores the environmental impacts posed by large-scale wind. Though avian mortality and noise caused controversy in the early years of wind development, improved technology and exhaustive siting assessments have minimized their impact. The aesthetic valuation of wind farms can be improved significantly with better design, siting, construction, and maintenance procedures, but opposition may increase as wind is developed on a large scale. Finally, this thesis summarizes collaborative work utilizing general circulation models to determine whether wind turbines have an impact of climate. The results suggest that the climatic impact is non-negligible at continental scales, but further research is warranted.

Crystal plastic earthquakes in dolostones: from slow to fast ruptures.

NASA Astrophysics Data System (ADS)

Passelegue, F. X.; Aubry, J.; Nicolas, A.; Fondriest, M.; Schubnel, A.; Di Toro, G.

2017-12-01

Dolostone is the most dominant lithology of the seismogenic upper crust around the Mediterranean Sea. Understanding the internal mechanisms controlling fault friction is crucial for understanding seismicity along active faults. Displacement in such fault zones is frequently highlighted by highly reflective (mirror-like) slip surfaces, created by thin films of nanogranular fault rock. Using saw-cut dolostone samples coming from natural fault zones, we conducted stick-slip experiments under triaxial loading conditions at 30, 60 and 90 MPa confining pressure and temperature ranging from 30 to 100 degrees C. At 30 and 65 degrees C, only slow rupture was observed and the experimental fault exhibits frictional behaviour, i.e. a dependence of normal stress on peak shear stress. At 65 degrees C, a strengthening behaviour is observed after the main rupture, leading to a succession of slow rupture. At 100 degrees C, the macroscopic behaviour of the fault becomes ductile, and no dependence of pressure on the peak shear stress is observed. In addition, the increase of the confining pressure up to 60 and 90 MPa allow the transition from slow to fast rupture, highlighted by the records of acoustic activity and by dynamic stress drop occurring in a few tens of microseconds. Using strain gages located along the fault surface and acoustic transducers, we were able to measure the rupture velocities during slow and fast rupture. Slow ruptures propagated around 0.1 m/s, in agreement with natural observations. Fast ruptures propagated up to supershear velocities, i.e. faster than the shear wave speed (>3500 m/s). A complete study of the microstructures was realized before and after ruptures. Slow ruptures lead to the production of mirror-like surface driven by the production of nanograins due to dislocation processes. Fast ruptures induce the production of amorphous material along the fault surface, which may come from decarbonation and melting processes. We demonstrate that the transition from slow to fast instabilities is observed due to an increase of the fault stiffness with increasing both temperature and confining pressure. This increase in the stiffness leads to an increase of the slip velocity during the main instability, which allow flash weakening processes and fast propagation of the seismic rupture.

Geochemical evidence for the existence of high-temperature hydrothermal brines at Vesuvio volcano, Italy

NASA Astrophysics Data System (ADS)

Chiodini, Giovanni; Marini, Luigi; Russo, Massimo

2001-07-01

A high-temperature hydrothermal system is present underneath the crater area of Vesuvio volcano. It is suggested that NaCl brines reside in the high-temperature reservoir and influence the chemical composition of the gases discharged by the fumaroles of the crater bottom (vents FC1, FC2, and FC5). These have typical hydrothermal compositions, with H 2O and CO 2 as major components, followed by H 2, H 2S, N 2, CH 4, and CO (in order of decreasing contents) and undetectable SO 2, HCl, and HF. Fumarolic H 2O is either meteoric water enriched in 18O through high-temperature water-rock oxygen isotope exchange or a mixture of meteoric and arc-type magmatic water. Fumarolic CO 2 is mainly generated by decarbonation reactions of marine carbonates, but the addition of small amounts of magmatic CO 2 is also possible. All investigated gas species (H 2O, CO 2, CO, CH 4, H 2, H 2S, N 2, and NH 3) equilibrate, probably in a saturated vapor phase, at temperatures of 360 to 370°C for vent FC1 and 430 to 445°C for vents FC2 and FC5. These temperatures are confirmed by the H 2-Ar geoindicator. The minimum salt content of the liquid phase coexisting with the vapor phase is ˜14.9 wt.% NaCl, whereas its maximum salinity corresponds to halite saturation (49.2-52.5 wt.% NaCl). These poorly constrained salinities of NaCl brines reflect in large uncertainties in total fluid pressures, which are estimated to be 260 to 480 bar for vents FC2 and FC5 and 130 to 220 bar for vent FC1. Pressurization in some parts of the hydrothermal system, and its subsequent discharge through hydrofracturing, could explain the relatively frequent seismic crises recorded in the Vesuvio area after the last eruption. An important heat source responsible for hydrothermal circulation is represented by the hot rocks of the eruptive conduits, which have been active from 1631 to 1944. Geochemical evidence suggests that no input of fresh magma at shallow depths took place after the end of the last eruptive period.

Positive feedback between strain localization and fluid flow at the ductile-brittle transition leading to Pb-Zn-Fe-Cu-Ag ore deposits in Lavrion (Greece)

NASA Astrophysics Data System (ADS)

Scheffer, Christophe; Tarantola, Alexandre; Vanderhaeghe, Olivier

2016-04-01

At the crustal scale, the ductile-brittle transition (DBT) might correspond to a physical barrier that separates a deep reservoir of metamorphic and magmatic fluids from a shallow reservoir of surficial fluids. Rock rheology, and thus the location of the DBT, is mainly governed by lithology, temperature and the presence/absence of fluids. Accordingly, the position of the DBT potentially evolves during orogenic evolution owing to thermal evolution and fluid circulation. In turn rocks are transferred across it during burial and exhumation. These processes induce connections between fluid reservoirs which might play a role on ore deposition. In this contribution, we discuss the impact of lithological heterogeneities on deformation, fluid flow and ore deposition based on the example of the Lavrion low-angle top-to-the-SSW detachment accommodating gravitational collapse of the Hellenides orogenic belt in Greece. The Lavrion peninsula, localized along the western boundary of the Attic-Cycladic Metamorphic Core Complex, is characterized by Pb-Zn-Fe-Cu-Ag ore mineralization mainly concentrated along a lithological contact (marble/schists) below and within a detachment shear zone. The mylonitic marble below the detachment shear zone is composed of white layers of pure marble alternating with blue layers containing impurities (SiO2, Al2O3, organic matter…). Development of the mylonitic fabric in competent impure blue marble is associated with its preferred dolomitization related to focused fluid infiltration. This mylonitic marble is cross-cut by several cataclastic horizons preferentially developed within the more competent impure blue marble and newly-crystallized dolomitic horizon. These cataclasites are invaded by fluorite and calcite gangue minerals showing locally Mn, Pb, Zn, Fe oxides and/or hydroxides, sphalerite, Ag-galena, Ag-sulfur and native Ag. Oxygen and carbon stable isotopes performed on marble sections point out decarbonation with magmatic contribution and fluid-rock interactions including organic matter present in the whole-rock during ore precipitation. These features show the positive feedback between localization of ductile-brittle deformation-recrystallization, fluid circulation and ore deposition. Accordingly, during orogenic gravitational collapse, the activation of mylonitic-cataclastic low-angle detachments, controlled at first order by temperature, are, at second order, influenced by lithologic heterogeneities that are determinant at localizing fluid circulation, allowing thus a multi-localization of the DBT and ore deposition.

A model to evaluate 100-year energy mix scenarios to facilitate deep decarbonization in the southeastern United States

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

Adkisson, Mary A.; Qualls, A. L.

The Southeast United States consumes approximately one billion megawatt-hours of electricity annually; roughly two-thirds from carbon dioxide (CO 2) emitting sources. The balance is produced by non-CO 2 emitting sources: nuclear power, hydroelectric power, and other renewables. Approximately 40% of the total CO 2 emissions come from the electric grid. The CO 2 emitting sources, coal, natural gas, and petroleum, produce approximately 372 million metric tons of CO 2 annually. The rest is divided between the transportation sector (36%), the industrial sector (20%), the residential sector (3%), and the commercial sector (2%). An Energy Mix Modeling Analysis (EMMA) tool wasmore » developed to evaluate 100-year energy mix strategies to reduce CO 2 emissions in the southeast. Current energy sector data was gathered and used to establish a 2016 reference baseline. The spreadsheet-based calculation runs 100-year scenarios based on current nuclear plant expiration dates, assumed electrical demand changes from the grid, assumed renewable power increases and efficiency gains, and assumed rates of reducing coal generation and deployment of new nuclear reactors. Within the model, natural gas electrical generation is calculated to meet any demand not met by other sources. Thus, natural gas is viewed as a transitional energy source that produces less CO 2 than coal until non-CO 2 emitting sources can be brought online. The annual production of CO 2 and spent nuclear fuel and the natural gas consumed are calculated and summed. A progression of eight preliminary scenarios show that nuclear power can substantially reduce or eliminate demand for natural gas within 100 years if it is added at a rate of only 1000 MWe per year. Any increases in renewable energy or efficiency gains can offset the need for nuclear power. However, using nuclear power to reduce CO 2 will result in significantly more spent fuel. More efficient advanced reactors can only marginally reduce the amount of spent fuel generated in the next 100 years if they are assumed to be available beginning around 2040. Thus closing the nuclear fuel cycle to reduce nuclear spent fuel inventories should be considered. Future work includes the incorporation of economic features into the model and the extension of the evaluation to the industrial sector. It will also be necessary to identify suitable sites for additional reactors.« less

Carbonation of subduction-zone serpentinite (high-pressure ophicarbonate; Ligurian Western Alps) and implications for the deep carbon cycling

NASA Astrophysics Data System (ADS)

Scambelluri, Marco; Bebout, Gray E.; Belmonte, Donato; Gilio, Mattia; Campomenosi, Nicola; Collins, Nathan; Crispini, Laura

2016-05-01

Much of the long-term carbon cycle in solid earth occurs in subduction zones, where processes of devolatilization, partial melting of carbonated rocks, and dissolution of carbonate minerals lead to the return of CO2 to the atmosphere via volcanic degassing. Release of COH fluids from hydrous and carbonate minerals influences C recycling and magmatism at subduction zones. Contradictory interpretations exist regarding the retention/storage of C in subducting plates and in the forearc to subarc mantle. Several lines of evidence indicate mobility of C, of uncertain magnitude, in forearcs. A poorly constrained fraction of the 40-115 Mt/yr of C initially subducted is released into fluids (by decarbonation and/or carbonate dissolution) and 18-43 Mt/yr is returned at arc volcanoes. Current estimates suggest the amount of C released into subduction fluids is greater than that degassed at arc volcanoes: the imbalance could reflect C subduction into the deeper mantle, beyond subarc regions, or storage of C in forearc/subarc reservoirs. We examine the fate of C in plate-interface ultramafic rocks, and by analogy serpentinized mantle wedge, via study of fluid-rock evolution of marble and variably carbonated serpentinite in the Ligurian Alps. Based on petrography, major and trace element concentrations, and carbonate C and O isotope compositions, we demonstrate that serpentinite dehydration at 2-2.5 GPa, 550 °C released aqueous fluids triggering breakdown of dolomite in nearby marbles, thus releasing C into fluids. Carbonate + olivine veins document flow of COH fluids and that the interaction of these COH fluids with serpentinite led to the formation of high-P carbonated ultramafic-rock domains (high-P ophicarbonates). We estimate that this could result in the retention of ∼0.5-2.0 Mt C/yr in such rocks along subduction interfaces. As another means of C storage, 1 to 3 km-thick layers of serpentinized forearc mantle wedge containing 50 modal % dolomite could sequester 1.62 to 4.85 Mt C/yr. We stress that lithologically complex interfaces could contain sites of both C release and C addition, further confounding estimates of net C loss at forearc and subarc depths. Sites of C retention, also including carbonate veins and graphite as reduced carbonate, could influence the transfer of slab C to at least the depths beneath volcanic fronts.

Oxalate Acid-Base Cements as a Means of Carbon Storage

NASA Astrophysics Data System (ADS)

Erdogan, S. T.

2017-12-01

Emission of CO2 from industrial processes poses a myriad of environmental problems. One such polluter is the portland cement (PC) industry. PC is the main ingredient in concrete which is the ubiquitous binding material for construction works. Its production is responsible for 5-10 % of all anthropogenic CO2 emissions. Half of this emission arises from the calcination of calcareous raw materials and half from kiln fuel burning and cement clinker grinding. There have long been efforts to reduce the carbon footprint of concrete. Among the many ways, one is to bind CO2 to the phases in the cement-water paste, oxides, hydroxides, and silicates of calcium, during early hydration or while in service. The problem is that obtaining calcium oxide cheaply requires the decarbonation of limestone and the uptake of CO2 is slow and limited mainly to the surface of the concrete due to its low gas permeability. Hence, a faster method to bind more CO2 is needed. Acid-base (AB) cements are fast-setting, high-strength systems that have high durability in many environments in which PC concrete is vulnerable. They are made with a powder base such as MgO and an acid or acid salt, like phosphates. Despite certain advantages over PC cement systems, AB cements are not feasible, due to their high acid content. Also, the phosphoric acid used comes from non-renewable sources of phosphate. A potential way to reduce the drawbacks of using phosphates could be to use organic acids. Oxalic acid or its salts could react with the proper powder base to give concrete that could be used for infrastructure hence that would have very high demand. In addition, methods to produce oxalates from CO2, even atmospheric, are becoming widespread and more economical. The base can also be an industrial byproduct to further lower the environmental impact. This study describes the use of oxalic acid and industrial byproducts to obtain mortars with mechanical properties comparable to those of PC mortars. It is demonstrated that an oxalate AB (OAB) cement concrete can partially replace PC concrete, for various applications. The strength gain of the OAB system is significantly faster, its heat of reaction higher, its chemical durability higher but its thermal durability lower than PC systems. OAB cements can put to good use oxalates produced from captured CO2.

Soil radon profile of the Alhama de Murcia Fault: implications in tectonic segmentation

NASA Astrophysics Data System (ADS)

Bejar-Pizarro, M.; Perez Lopez, R.; Fernández Cortés, A.; Martínez-Díaz, J. J.; Staller, A.; Sánchez-Malo, A.; Sanz, E.; Cuezva, S.; Sánchez-Moral, S.

2017-12-01

Soil radon exhalation in active faults has been reported in several cases. Mobilization of radon gas in tectonic areas is related to CO2emission, acting as gas carrier from deeper fractured zones. Fluctuation of radon values can be correlated with earthquake occurrence. We have used the soil radon emission for characterizing different tectonic segment of the Alhama de Murcia Fault (FAM), one of the most active on-shore tectonic faults in Spain. The FAM is a NE-SW trending strike-slip fault with reverse component, 90 km long and it is capable to trigger M7 earthquakes, as far as several paleoseismic studies shown. The last destructive earthquake took place in 2011 and killed 9 people. Tectonic segmentation of this fault has been proposed, with a tectonic slip-rate close to 0.1 mm/yr from geomorphic evidence, whereas 0.5 mm/yr has been suggested from GPS geodetic measurements. We have developed a perpendicular profile for measuring the soil radon exhalation, in relationship with three principal segments of FAM from west to east: (1) Goñar-Lorca segment, (2) Lorca Totana segment and (3) Alhama segment. We have introduced radon passive detectors equipped with LR115 films in colluvium detritic deposits and at 0.8 m depth. Using detritic deposits affected by Quaternary fault movement we assure equal permeability conditions for radon transport. We used passive closed housings type DRF, with a filter that avoid thoron disturbance. Results show the largest values of radon emission close to the Quaternary surface ruptures (ca 3-5.5 kBq/m3). Furthermore, the Goñar segment exhibits the highest value (6 kBq/m3) although the Lorca segment shows an isotopic signal of 13dCO2 (-7.24‰) which indicates this is a mantle-rootled CO2, i.e. non-soil derived CO2 flux, likely related to CO2 produced by thermal decarbonation of underlying sedimentary rocks containing more marine carbonate minerals. These results are part of the combined Spanish projects GEIs-SUB (CGL2016- 78318-C2-1-R and CGL2016-78318-C2-2-R) and INTERGEO and SISMOSIMA (CGL2013-47412-C2-1-P, CGL2013-47412-C2-2-P).

Oxygen isotope geochemistry of mafic magmas at Mt. Vesuvius

NASA Astrophysics Data System (ADS)

Dallai, Luigi; Raffaello, Cioni; Chiara, Boschi; Claudia, D'oriano

2010-05-01

Pumice and scoria from different eruptive layers of Mt. Vesuvius volcanic products contain mafic minerals consisting of High-Fo olivine and Diopsidic Pyroxene. These phases were crystallized in unerupted trachibasaltic to tephritic magmas, and were brought to surface by large phonolitic/tephri-phonolitic (e.g. Avellino and Pompei) and/or of tephritic and phono-tephritic (Pollena) eruptions. A large set of these mm-sized crystals was accurately separated from selected juvenile material and measured for their chemical compositions (EPMA, Laser Ablation ICP-MS) and 18O/16O ratios (conventional laser fluorination) to constrain the nature and evolution of the primary magmas at Mt. Vesuvius. Uncontaminated mantle δ18O values are hardly recovered in Italian Quaternary magmas, mostly due to the widespread occurrence of crustal contamination of the primary melts during their ascent to the surface (e.g. Alban Hills, Ernici Mts., and Aeolian Islands). At Mt. Vesuvius, measured olivine and clinopyroxene share quite homogeneous chemical compositions (Olivine Fo 85-90 ; Diopside En 45-48, respectively), and represent phases crystallized in near primary mafic magmas. Trace element composition constrains the near primary nature of the phases. Published data on volatile content of melt inclusions hosted in these crystals reveal the coexistence of dissolved water and carbon dioxide, and a minimum trapping pressure around 200-300 MPa, suggesting that crystal growth occurred in a reservoir at about 8-10 km depth. Recently, experimental data have suggested massive carbonate assimilation (up to about 20%) to derive potassic alkali magmas from trachybasaltic melts. Accordingly, the δ18O variability and the trace element content of the studied minerals suggest possible contamination of primary melts by an O-isotope enriched, REE-poor contaminant like the limestone of Vesuvius basement. Low, nearly primitive δ18O values are observed for olivine from Pompeii eruption, although still above the range of typical mantle minerals. The δ18Oolivine and δ18Ocpxof the minerals from all the studied eruptions define variable degrees of carbonate interaction and magma crystallization for the different eruptions, and possibly within the same eruption, and show evidence of oxygen isotope equilibrium at high temperature. However, energy-constrained AFC model suggest that carbonate assimilation was limited. On the basis of our data, we suggest that interaction between magma and a fluxing, decarbonation-derived CO2 fluid may be partly accounted for the measured O-isotope compositions.

Kinematics of fibrous vein growth: insights from stable isotopes and trace element data

NASA Astrophysics Data System (ADS)

Fischer, M. P.; Lefticariu, L.; Romanek, C.; Perry, E. C.

2005-12-01

Veins are important recorders of thermal, hydrological, structural, and geochemical conditions during deformation. Fibrous or bladed veins are particularly useful, because the mineral fibers are believed to grow continuously or episodically over what may be a significant geologic time period. Thus, individual mineral fibers document the complex, dynamic changes occurring coeval with vein growth and mineral precipitation. Geochemical and structural analyses have been used to constrain the kinematic history of a bed-parallel fibrous calcite vein from the Upper Jurassic La Casita Formation, Sierra Madre Oriental, Mexico. The La Casita Formation, correlative with the Smackover Formation of the northern US Gulf Coast, consists of shale and is part of a sedimentary succession that unconformably overlies evaporites of the Minas Viejas Formation. The fibrous vein examined in this study was taken from the backlimb of the frontal fold of the Monterrey salient near Saltillo. Optical petrographic observation reveals that the calcite fibers have blade or tapering lath shapes with widths from 0.1-1.0 mm. Other minerals present in the vein are pyrite, gypsum, bitumen, and iron oxides. High-resolution, closely spaced stable isotope and elemental analyses were carried out along five traverses across the vein width. The d18O values vary in a narrow range, with an average value of +20.8 permil (VSMOW). The d13C values increase systematically along the fibers, from the walls of the vein toward the suture plane. In all five traverses, the d13C increase is relatively constant, with lower values next to the vein wall (+1.2 to +1.6 permil PDB) and higher values along the suture line (+3.6 to +4.1 permil PDB). The vein minerals, fibrous calcite and accessory pyrite, are interpreted to be the products of high temperature reactions between light hydrocarbons and dissolved sulfate, known as thermochemical sulfate reduction (TSR). Reactants such as light hydrocarbons and products such as CO2, H2S, and H2O contributed to what are interpreted to have been high fluid pressures during vein growth. The origin of vein minerals is probably related to: (1) methanogenesis and decarbonation reactions within the shale, and (2) migration of high-temperature brine during late stages of folding.

Carbon degassing from the lithosphere

NASA Astrophysics Data System (ADS)

Mörner, Nils-Axel; Etiope, Giuseppe

2002-06-01

So far, the role of present-day Earth degassing in global C budget and climate effects has been focused to volcanic emissions. The non-volcanic escape of CO 2-CH 4 from the upper mantle, from carbonate bearing rocks in the crust, from hydrocarbon accumulations and from surface deposits and processes is here discussed in detail. An inventory of recent available data is presented. For the first time, a so large quantity of data is considered altogether showing clearly that the geological flux of carbon was previously significantly underestimated. Several lines of evidence show that non-volcanic C fluxes in «colder» environments are much greater than generally assumed. Local and regional data suggest that metamorphic decarbonation, hydrocarbon leakage and mud volcanoes could be significant CO 2-CH 4 sources at global scale. Moreover, extensive surface gas-geochemical observations, including soil-atmosphere flux investigations, open the possibility that ecosystems controlled by biogenic activity (soil, permafrost, seawater) can host important components of endogenous C gas (geogas), even in the absence of surface gas manifestations. This would imply the existence of a geological diffuse, background emission over large areas of our planet. New theories concerning the occurrence of pervasive geogas and lithospheric processes of C-gas production («lithospheric loss in rigidity») can be taken as novel reference and rationale for re-evaluating geological sources of CO 2 and CH 4, and an important endeavour and work prospect for the years to come. Our survey shows that it is still very hard to arrive at a meaningful estimate of the lithospheric non-volcanic degassing into the atmosphere. Orders of 10 2-10 3 Mt CO 2/year can be provisionally considered. Assuming as lower limit for a global subaerial volcanic degassing 300 Mt/year, the lithosphere may emit directly into the atmosphere at least 600 Mt CO 2/year (about 10% of the C source due to deforestation and land-use exchange), an estimate we still consider conservative. It is likely that temporal variations of lithosphere degassing, at Quaternary and secular scale, may influence the atmospheric C budget. The present-day lithosphere degassing would seem higher than the value considered to balance at Ma time-scale the CO 2 uptake due to silicate weathering.

Deep-level magma dehydration and ascent rates at Mt. Etna (Sicily, Italy)

NASA Astrophysics Data System (ADS)

Armienti, P.; Perinelli, C.; Putirka, K.

2012-04-01

Magma ascent velocity, v (dH/dt; H = depth, t = time),can be determined from ascent rate (dP/dt), and rate of cooling (dT/dt): v= 1/(rgpg) (dP/dT)(dT/dt) where r is magma density, P is pressure, T is temperature and g is the acceleration of gravity. This equation for v provides a key to investigating the relationships between initial ascent rate of magma and the depths of magma dehydration, and v can be calculated using pressure and temperature (P - PH2O - T) estimates from mineral-liquid thermobarometry, and cooling rates inferred from Crystal Size Distribution (CSD) theory. For recent Mt. Etna lava flows, both dP/dT and dT/dt have been well characterized based, respectively, on clinopyroxene thermobarometry, and clinopyroxene CSDs (the latter yields dT/dt = 2x10-6 °C/s). Deep-level (>20 km) magma ascent rates range from practically 0 (where clinopyroxene P - T estimates form a cluster, and so dP/dT ≈ 0), to about 10 m/hr for flows that yield very steep P - T trajectories. Many lava flows at Mt. Etna yield P - T paths that follow a hydrous (about 3% water) clinopyroxene saturation surface, which closely approximates water contents obtained from melt inclusions. Independent assessments of deep level water content yield ascent rates of ~1 m/hr, in agreement with the slowest rates derived for magma effusion or vapor-driven ascent (~0.001 to >0.2 m/s, or 3.6 to 720 m/hr). Changes in P - T slopes, as obtained by pyroxene thermobarometry, indicate an upward acceleration of magma, which may be due to the onset of deep-level magma dehydration linked to the non-ideal behavior of water and CO2 mixtures that induce a deep-level maximum of water loss at P ≈ 0.4 MPa at T ≈ 1200 ° C for a CO2 content >1000ppm. Melt inclusion data on CO2 and H2O contents are successfully reproduced and interpreted in a context of magma dehydration induced by a CO2 flux possibly deriving by decarbonation reaction of the carbonate fraction of the Capo D'Orlando flysch.

Geological constraints on continental arc activity since 720 Ma: implications for the link between long-term climate variability and episodicity of continental arcs

NASA Astrophysics Data System (ADS)

Cao, W.; Lee, C. T.

2016-12-01

Continental arc volcanoes have been suggested to release more CO2 than island arc volcanoes due to decarbonation of wallrock carbonates in the continental upper plate through which the magmas traverse (Lee et al., 2013). Continental arcs may thus play an important role in long-term climate. To test this hypothesis, we compiled geological maps to reconstruct the surface distribution of granitoid plutons and the lengths of ancient continental arcs. These results were then compiled into a GIS framework and incorporated into GPlates plate reconstructions. Our results show an episodic nature of global continental arc activity since 720 Ma. The lengths of continental arcs were at minimums during most of the Cryogenian ( 720-670 Ma), the middle Paleozoic ( 460-300 Ma) and the Cenozoic ( 50-0 Ma). Arc lengths were highest during the Ediacaran ( 640-570 Ma), the early Paleozoic ( 550-430 Ma) and the entire Mesozoic with peaks in the Early Triassic ( 250-240 Ma), Late Jurassic-Early Cretaceous ( 160-130 Ma), and Late Cretaceous ( 90-65 Ma). The extensive continental arcs in the Ediacaran and early Paleozoic reflect the Pan-African events and circum-Gondwana subduction during the assembly of the Gondwana supercontinent. The Early Triassic peak is coincident with the final closure of the paleo-Asian oceans and the onset of circum-Pacific subduction associated with the assembly of the Pangea supercontinent. The Jurassic-Cretaceous peaks reflect the extensive continental arcs established in the western Pacific, North and South American Cordillera, coincident with the initial dispersal of the Pangea. Continental arcs are favored during the final assembly and the early-stage dispersal of a supercontinent. Our compilation shows a temporal match between continental arc activity and long-term climate at least since 720 Ma. For example, continental arc activity was reduced during the Cryogenian icehouse event, and enhanced during the Early Paleozoic and Jurassic-Cretaceous greenhouse events. This coherence provides further evidence that continental arcs may play an important role in controlling long-term climate evolution. CO2 degassing fluxes from continental arcs should be incorporated into global, long-term climate models. Our work provides a quantitative framework for estimating these fluxes.

[NH4+-N removal stability of zeolite media packed multistage-biofilm system for coke-plant wastewater treatment].

PubMed

Zhao, Wen-Tao; Huang, Xia; He, Miao; Zhang, Peng-Yi; Zuo, Chen-Yan

2009-02-15

The practical ammonia stripping effectiveness of coke-plant wastewater treatment may vary widely, and high NH4+-N shock loading will lead to the fluctuation of residual NH4+-N concentration of biological effluent. A zeolite media packed multistage-biofilm system (ZMBS) was used for coke-plant wastewater treatment for enhancing the NH4+-N treatment ability of the bio-system to shock loading, as well as achieving high COD removal efficiency. Treatment performance during steady-state and shock loading and transformation of organic pollutants in the system were investigated systematically. The experiment results indicated that when the system was operated at NH4+-N loading 0.21 kg/(m3 x d) and COD loading < or = 1.35 kg/(m3 x d), the average effluent NH4+-N and COD concentrations were (2.2 +/- 1.2) mg/L, (228 +/- 60) mg/L with average removal efficiencies of (99.1 +/- 0.5)% and (86.0 +/- 2.6)%. During the twice NH4+-N shock loadings [0.03 kg/(m3 x d) and 0.06 kg/(m3 x d)], ZMBS showed a strong resisting ability with average removal efficiencies of 99.0% and 92.9% higher than those of a compared system's 96.8% and 89.3%. By monitoring the change of water quality along the length of the ZMBS's cells, two function zones for different pollutant removal were found to exist, named as decarbonization/nitrification (C/N) zone and nitrification (N) zone, and the NH4+-N removal rate in N zone was 2-8 times as that in C/N zone. TOC concentrations of organic matters with relative molecular weight < 1 x 10(3), 1 x 10(3) to 1 x 10(4), and > 1 x 10(4), were 227.6, 104.8 and 35.0 mg/L in raw wastewater, and 31.2, 22.9 and 31.5 mg/L in the effluent, respectively. Organic matters with relative molecular weight < 1 x 10(3) and 1 x 10(3) to 1 x 10(4) in raw wastewater were removed effectively by ZMBS, but those with relative molecular weight > 1x 10(3) were the main remained substances in the effluent.

Rapid solar-thermal decarbonization of methane

NASA Astrophysics Data System (ADS)

Dahl, Jaimee Kristen

Due to the ever-increasing demand for energy and the concern over the environmental impact of continuing to produce energy using current methods, there is interest in developing a hydrogen economy. Hydrogen is a desirable energy source because it is abundant in nature and burns cleanly. One method for producing hydrogen is to utilize a renewable energy source to obtain high enough temperatures to decompose a fossil fuel into its elements. This thesis work is directed at developing a solar-thermal aerosol flow reactor to dissociate methane to carbon black and hydrogen. The technology is intended as a "bridge" between current hydrogen production methods, such as conventional steam-methane reformers, and future "zero emission" technology for producing hydrogen, such as dissociating water using a renewable heating source. A solar furnace is used to heat a reactor to temperatures in excess of 2000 K. The final reactor design studied consists of three concentric vertical tubes---an outer quartz protection tube, a middle solid graphite heating tube, and an inner porous graphite reaction tube. A "fluid-wall" is created on the inside wall of the porous reaction tube in order to prevent deposition of the carbon black co-product on the reactor tube wall. The amorphous carbon black produced aids in heating the gas stream by absorbing radiation from the reactor wall. Conversions of 90% are obtained at a reactor wall temperature of 2100 K and an average residence time of 0.01 s. Computer modeling is also performed to study the gas flow and temperature profiles in the reactor as well as the kinetics of the methane dissociation reaction. The simulations indicate that there is little flow of the fluid-wall gas through the porous wall in the hot zone region, but this can be remedied by increasing the inlet temperature of the fluid-wall gas and/or increasing the tube permeability only in the hot zone region of the wall. The following expression describes the kinetics of methane dissociation in a solar-thermal fluid-wall reactor: dXdt=5.8x108 exp-155,600RT 1-X 7.2s-1. The experimental and theoretical work reported in this thesis is the groundwork that will be utilized in scaling up the reactor to produce hydrogen in distributed or centralized facilities.

CO2 release from variable carbonate compositions via thermal breakdown and magmatic assimilation at mid-crustal depths

NASA Astrophysics Data System (ADS)

Carter, L. B.; Dasgupta, R.

2017-12-01

Assimilation of crustal limestone in intruding magma has been found to release potentially significant [1-2] but varying amounts of CO2 to the exogenic system depending on pressure, temperature and magma composition [3-4]. However, most natural carbonates range from impure calcite to dolomite or ankerite and their behavior during hydrothermal processes and magma intrusion are less known [2,5-6]. We experimentally investigated both the thermal stability and reactions with hydrous basaltic and dacitic magmas at 800-1200 °C at 0.5 GPa for 3 Fe-bearing dolomite-calcite solid solutions. Dolomite breaks down into Fe-Mg oxides and CO2 at ≤800 °C. With increasing carbonate Ca/Mg, higher temperature is needed to reach similar decarbonation levels and the transition from Fe-dolomite + Mg-calcite as stable carbonate phases to only the latter. In the presence of magmas, carbonate is Mg-calcite or calcite, in addition to minerals seen in previous pure dolomite studies and natural systems [2-4,7-9], including ferropericlase, diopside, olivine with dolomite, anorthite with calcic carbonate, and wollastonite with rhyolitic melts. Thermal breakdown and assimilation increase with Mg/Ca ratios in the starting carbonate (<50% breakdown & <60% assimilation, respectively). At identical conditions, dolomite assimilation by dacite can release 4 times as much CO2 as limestone, surpassing basalt-dolomite. Though greater than other dacite-carbonate reactions, basalt releases a similar amount regardless of carbonate composition. With Mg/Ca≥0.48, release of CO2 from destabilization even at low temperature (≥900 °C) exceeds that from assimilation (≥1000 °C). Thus magma-carbonate interaction may have contributed several times the current arc output [10] to Earth's past atmosphere, which necessitates cataloging carbonate compositions globally for consideration in climate modeling. [1] Aiuppa et al. 2017 ESciRev (168)24-47; [2] Lee and Lackey 2015 Elem (11)125-130; [3] Carter and Dasgupta 2015 EPSL (427) 202-214; [4] Carter and Dasgupta 2016 G3 (17)3893-3916; [5] Warren 2000 ESciRev (52)1:81; [6] Franzolin et al. 2011 CMP (161)213-227; [7] Jolis et al. 2013 CMP (166)1335-1353; [8] Iacono-Marziano et al. 2008 CMP (155)719-738; [9] Mollo et al. 2010 Lithos (114)503-514; [10] Burton et al 2013 RevMinGeochem (75) 323-254.

Deep Reductions in Greenhouse Gas Emissions from the California Transportation Sector: Dynamics in Vehicle Fleet and Energy Supply Transitions to Achieve 80% Reduction in Emissions from 1990 Levels by 2050

NASA Astrophysics Data System (ADS)

Leighty, Wayne Waterman

California's "80in50" target for reducing greenhouse gas emissions to 80 percent below 1990 levels by the year 2050 is based on climate science rather than technical feasibility of mitigation. As such, it raises four fundamental questions: is this magnitude of reduction in greenhouse gas emissions possible, what energy system transitions over the next 40 years are necessary, can intermediate policy goals be met on the pathway toward 2050, and does the path of transition matter for the objective of climate change mitigation? Scenarios for meeting the 80in50 goal in the transportation sector are modelled. Specifically, earlier work defining low carbon transport scenarios for the year 2050 is refined by incorporating new information about biofuel supply. Then transition paths for meeting 80in50 scenarios are modelled for the light-duty vehicle sub-sector, with important implications for the timing of action, rate of change, and cumulative greenhouse gas emissions. One aspect of these transitions -- development in the California wind industry to supply low-carbon electricity for plug-in electric vehicles -- is examined in detail. In general, the range of feasible scenarios for meeting the 80in50 target is narrow enough that several common themes are apparent: electrification of light-duty vehicles must occur; continued improvements in vehicle efficiency must be applied to improving fuel economy; and energy carriers must de-carbonize to less than half of the carbon intensity of gasoline and diesel. Reaching the 80in50 goal will require broad success in travel demand reduction, fuel economy improvements and low-carbon fuel supply, since there is little opportunity to increase emission reductions in one area if we experience failure in another. Although six scenarios for meeting the 80in50 target are defined, only one also meets the intermediate target of reducing greenhouse gas emissions to 1990 levels by the year 2020. Furthermore, the transition path taken to reach any one of these scenarios can differ in cumulative emissions by more than 25 percent. Since cumulative emissions are the salient factor for climate change mitigation and the likelihood of success is an important consideration, initiating action immediately to begin the transitions indicated for achieving the 80in50 goal is found to be prudent.

Continental Subduction: Mass Fluxes and Interactions with the Wider Earth System

NASA Astrophysics Data System (ADS)

Cuthbert, S. J.

2011-12-01

Substantial parts of ultra-high pressure (UHP) terrains probably represent subducted passive continental margins (PCM). This contribution reviews and synthesises research on processes operating in such systems and their implication for the wider Earth system. PCM sediments are large repositories of volatiles including hydrates, nitrogen species, carbonates and hydrocarbons. Sediments and upper/ mid-crustal basement are rich in incompatible elements and are fertile for melting. Lower crust may be more mafic and refractory. Juvenile rift-related mafic rocks also have the potential to generate substantial volumes of granitoid melts, especially if they have been hydrated. Exposed UHP terrains demonstrate the return of continental crust from mantle depths, show evidence for substantial fluxes of aqueous fluid, anatexis and, in entrained orogenic peridotites, metasomatism of mantle rocks by crust- derived C-O-H fluids. However, substantial bodies of continental material may never return to the surface as coherent masses of rock, but remain sequestered in the mantle where they melt or become entrained in the deeper mantle circulation. Hence during subduction, PCM's become partitioned by a range of mechanisms. Mechanical partitioning strips away weaker sediment and middle/upper crust, which circulate back up the subduction channel, while denser, stronger transitional pro-crust and lower crust may "stall" near the base of the lithosphere or be irreversibly subducted to join the global mantle circulation. Under certain conditions sediment and upper crustal basement may reach depths for UHPM. Further partitioning takes place by anatexis, which either aids stripping and exhumation of the more melt-prone rock-masses through mechanical softening, or separates melt from residuum so that melt escapes and is accreted to the upper plate leading to "undercrusting", late-orogenic magmatism and further refinement of the crust. Melt that traverses sections of mantle will interact with it causing metasomatism and refertilisation. Partitioning also takes place by solid-fluid and melt-fluid partitioning. Dehydration may take place both during subduction and exhumation, and fluxes between dehydrating and hydrating rock masses influence the internal fluid budget of the orogen (essential for eclogitisation and densification of mafic lithologies). Ascending granitic melts advect dissolved water to shallow levels, or even the atmosphere. Irreversible subduction of PCM sediment carries water plus nitrogen species to the deeper mantle. Decarbonation of voluminous PCM carbonates depends on thermal regime and may release a pulse of CO2 to the atmosphere, but is limited in colder subduction zones hence transferring large volumes of carbon to the deep mantle. This may ultimately be mobilised by melting or dissolution to form fluid media for diamond formation.

Rapid change of atmosphere on the Hadean Earth: Beyond Habitable Trinity on a tightrope

NASA Astrophysics Data System (ADS)

Arai, T.; Maruyama, S.

2014-12-01

Surface environment of Hadean Earth is a key to bear life on the Earth. All of previous works assumed that high pCO2 has been decreased to a few bars in the first a few hundreds millions of years (e.g., Zhanle et al., 2011). However, this process is not easy because of material and process barriers as shown below. Four barriers are present. First, the ultra-acidic pH (<0.1) of 4.4Ga ocean prevented the precipitation of carbonates at mid-oceanic ridge through water-rock interaction after the birth of primordial ocean driven by plate tectonics or pseudo-plate tectonics system. To overcome this barrier, primordial (anorthosite + KREEP) continents must have been above sea-level to increase pH rapidly through hydrological process. Second, major cap rocks on the Hadean oceanic crust must have been komatiite with minor basaltic rocks to precipitate carbonates through water-rock interaction and transport them into mantle through subduction at higher than the intermediate P/T geotherm on the Benioff plane. If not, carbonate minerals are all decarbonated at shallower depths than the Moho plane. Komatiite production depends on mantle potential temperature which must have been rapidly decreased to yield only Fe-enriched MORB by 3.8Ga. Third, the primordial continents composed of anorthosite with subordinate amounts of KREEP basalts must have been annihilated by 4.0Ga to alter pH to be possible to precipitate carbonates by hydrothermal process. The value of pCO2 must have been decreased down to a few bars from c.a. 50 bars at TSI (total surface irradiance) = 75% under the restricted time limit. If failed, the Earth must have been Venus state which is impossible to bear life on the planet. Fourth is the role of tectonic erosion to destroy and transport the primordial continent of anorthosite into deep mantle by subduction. Anorthosite + KREEP was the mother's milk grow life on the Earth, but disappeared by 4.0Ga or even earlier, but alternatively granites were formed and accumulated on the Earth to supply nutrients for life. This is time-dependent process to increase new continents. Fifth is the water content of 3-5km thick, if the value was over, no way to bear life nor evolution afterwards. After all, the Hadean Earth has passed the really risky tightrope processes to bear life. If any of above five conditions was lost, life has not been appeared.

A geochemical approach for assessing the possible uses of the geothermal resource in the eastern sector of the Sabatini Volcanic District (Central Italy)

NASA Astrophysics Data System (ADS)

Cinti, Daniele; Tassi, Franco; Procesi, Monia; Brusca, Lorenzo; Cabassi, Jacopo; Capecchiacci, Francesco; Delgado Huertas, Antonio; Galli, Gianfranco; Grassa, Fausto; Vaselli, Orlando; Voltattorni, Nunzia

2017-04-01

The Sabatini Volcanic District (SVD) hosts a hydrothermal reservoir heated by the post-magmatic activity that affected the peri-Tyrrhenian sector of central Italy, giving rise to a number of thermal and mineral discharges. In this study, a complete geochemical and isotopic dataset based on the composition of 215 water and 9 bubbling gases, collected from the eastern sector of this huge hydrothermal system, is reported. The main aims are to (i) investigate the fluid sources and the main chemical-physical processes controlling the fluid chemistry and (ii) construct a conceptual fluid circulation model to provide insights into the possible use(s) of the geothermal resource. The fluid discharges are fed by two main aquifers, characterized by: (1) a Ca-HCO3 to Ca(Na)-HCO3 composition, typical of a shallow hydrological circuit within volcanic and sedimentary formations, and (2) a Ca-HCO3(SO4) to Na(Ca)-HCO3(Cl) composition, produced by the interaction of CO2-rich fluids with Mesozoic and Triassic carbonate-evaporite rocks. A thick sequence of low-permeability volcanic products represents a physical barrier between the two fluid reservoirs. As commonly occurring in central-southern Italy, CO2 is mainly produced by thermo-metamorphic decarbonation within the carbonate-evaporite reservoir, with minor contribution of mantle CO2. A dominant crustal source is also indicated by the relatively low R/Ra values (0.07-1.04). Methane and light hydrocarbons are mostly thermogenic, whereas H2S derives from thermogenic reduction of the Triassic anhydrites. Slightly positive 15N/14N values suggest minor N2 contribution from deep sedimentary sources. On the whole, a comparison of these geochemical features with those of the thermal fluids from the western portion of SVD highlights an eastward increasing influence of the shallow aquifer on the deep-originated fluids, likely caused by the proximity of the Apennine range from where the meteoric water, recharging the hydrothermal system, permeate. Accordingly, gas geothermometry in the CH4-CO2-H2 and H2S-CO2-H2 systems suggests equilibrium temperatures <200 °C, i.e. significantly lower than those measured in fluids from deep geothermal wells (300 °C). Although mitigated by the short distance from the Apennine range, the thermal anomaly recognized by fluid geochemistry in the eastern SVD makes this area suitable for direct exploitation of the geothermal resource.

How the Timing of Climate Change Policy Affects Infrastructure Turnover in the Electricity Sector: Engineering, Economic and Policy Considerations

NASA Astrophysics Data System (ADS)

Izard, Catherine Finlay

The electricity sector is responsible for producing 35% of US greenhouse gas (GHG) emissions. Estimates suggest that ideally, the electricity sector would be responsible for approximately 85% of emissions abatement associated with climate polices such as America's Clean Energy and Security Act (ACES). This is equivalent to ˜50% cumulative emissions reductions below projected cumulative business-as-usual (BAU) emissions. Achieving these levels of emissions reductions will require dramatic changes in the US electricity generating infrastructure: almost all of the fossil-generation fleet will need to be replaced with low-carbon sources and society is likely to have to maintain a high build rate of new capacity for decades. Unfortunately, the inertia in the electricity sector means that there may be physical constraints to the rate at which new electricity generating capacity can be built. Because the build rate of new electricity generating capacity may be limited, the timing of regulation is critical---the longer the U.S. waits to start reducing GHG emissions, the faster the turnover in the electricity sector must occur in order to meet the same target. There is a real, and thus far unexplored, possibility that the U.S. could delay climate change policy implementation for long enough that it becomes infeasible to attain the necessary rate of turnover in the electricity sector. This dissertation investigates the relationship between climate policy timing and infrastructure turnover in the electricity sector. The goal of the dissertation is to answer the question: How long can we wait before constraints on infrastructure turnover in the electricity sector make achieving our climate goals impossible? Using the Infrastructure Flow Assessment Model, which was developed in this work, this dissertation shows that delaying climate change policy increases average retirements rates by 200-400%, increases average construction rates by 25-85% and increases maximum construction rates by 50-300%. It also shows that delaying climate policy has little effect on the age of retired plants or the stranded costs associated with premature retirement. In order for the electricity sector to reduce emissions to a level required by ACES while limiting construction rates to within achievable levels, it is necessary to start immediately. Delaying the process of decarbonization means that more abatement will be necessary from other sectors or geoengineering. By not starting emissions abatement early, therefore, the US forfeits its most accessible abatement potential and increases the challenge of climate change mitigation unnecessarily.

Carbon and nitrogen isotopic analysis of coral-associated nitrogen in rugose corals of the Middle Devonian, implications for paleoecology and paleoceanography.

NASA Astrophysics Data System (ADS)

Hickey, A. N.; Junium, C. K.; Uveges, B. T.; Ivany, L. C.; Martindale, R. C.

2017-12-01

The Middle Devonian Appalachian Basin of Central New York hosts an extraordinary diversity of well-studied fossil invertebrates within the shallow marine sequences of the Givetian Age, Hamilton Group. Of particular interest are a series of aerially expansive coral beds with diverse assemblages of rugose corals. These well-preserved specimens provide an excellent opportunity to test the feasibility of δ15N and δ13C analyses in rugose corals in an effort to resolve outstanding issues regarding their paleoecology and ontogeny as well environmental dynamics within the Devonian Appalachian Basin. Here we present carbon and nitrogen isotope analyses of the rugose corals Heliophyllum and Siphonophrentis from the Joshua Coral Bed. Corals were cleaned of the host calcareous shale and sonicated sequentially in deionized water and methanol, and then oxidatively cleaned. Cleaned corals were sectioned into 0.5cm billets to obtain enough residual organic material for analysis. The organic content of the corals is low, but nanoEA allows for serial sampling of 5-10 samples per coral. Coral sections were decarbonated and the residual organic material is filtered and dried prior to analysis. Coral organic matter is analyzed in triplicate using nanoEA, which is a cryo-trapping, capillary focusing technique for δ15N and δ13C. The δ15N of organic matter extracted from rugose corals is, on average, enriched by 2-4‰ relative to the bulk nitrogen in the host rock. As well, the δ13C of organic carbon from the corals is 13C-enriched relative to the bulk rock, but to a lesser degree (no more than 1.5‰). Assuming that the bulk rock carbon and nitrogen are largely representative of the long-term primary production background, the modest enrichment is consistent with a trophic effect, and that rugose corals are likely planktivores. In an individual coral, δ15N ranges by 3-4‰ over its length, and when adjusted for trophic enrichment varies around the average δ15N of bulk sedimentary organic matter (+2.0‰). There is no apparent trajectory in the isotopic composition of organic matter, which suggests that over the sampled life history of the corals we cannot resolve any ontogenetic trends. Therefore, the variability in the δ15N of the coral organic matter likely reflects short-term variability in basinal conditions or changes in coral food supply.

Key parameters for low-grade fine-grained iron ore valorization: lower environmental impact through reduced waste.

NASA Astrophysics Data System (ADS)

Wagner, Christiane; Orberger, Beate; Tudryn, Alina; Baptiste, Benoît; Wirth, Richard; Morgan, Rachel; Miska, Serge

2016-04-01

In low-grade banded iron formations (BIFs), a large part of the iron is related to micro- and nano- metric iron-bearing inclusions within quartz and/or carbonates, mainly dolomite (~ 20 to 50 μm). Low-grade fine grained iron ore present two types of environmental risks: a) they are often stocked as tailings. For example, the recent disaster (5th of November 2015) in the Minas Gerais district, Brazil, was caused by the collapse of the Fundão tailings dam at an open cast mine; b) during beneficiation significant amounts of dust are generated also leading to metal loss. A laminated BIF studied from a drill core at Àguas Claras Mine, Quadrilátero Ferrífero, Brazil, contains 26.71 wt. % total iron, 0.2 wt. % SiO2, 0.32 wt.% MnO, 15.46 wt. % MgO, 22.32 wt.% CaO, 0.09 wt. % P2O5, < 0.05 wt. % Al2O3, 0.15 wt. % H2O and 34.08 wt. % CO2. Environmental hazardous elements are present as traces (As: 3-20 ppm, Cd: 0-0.7 ppm; Cr: 0.05-60 ppm, Pb: up to 55 ppm; U: up to 8 ppm). Dolomite and quartz bands alternate with hematite bands. Raman spectroscopy, X-ray diffraction and FIB-TEM analyses reveal that the micro- and nano- metric inclusions in dolomite are hematite and minor goethite, partly occurring as clusters in voids. Curie Balance analyses were carried out at different heating steps and temperatures on whole rock samples and a synthetic mix of decarbonated sample and pure dolomite. X-ray diffraction on the products of the heating experiments shows that that hematite is stable and new phases: magnesioferrite (MgFe2O4), lime (CaO), periclase (MgO), portlandite (Ca(OH)2) and srebrodoskite (Ca2Fe2O5) were formed between 680 °C and 920 °C. These findings promote the economic use of low grade ores rather than their stockpiling as tailings. The presence of OH-bearing goethite reduces the sintering temperature. After having separated coarse hematite from barren dolomite and quartz, a low temperature sintering of the inclusion-bearing dolomite/quartz leads to transformations into phases with higher magnetic susceptibilities (such as hematite and magnesioferrite). The entire Fe and Fe/Mg oxide feed can then pass through wet-high intensity magnetic separation after crushing. Intelligent processing of these ore types can minimize the two above mentioned risk factors.

Fault Lubrication and Earthquake Propagation in Thermally Unstable Rocks

NASA Astrophysics Data System (ADS)

de Paola, Nicola; Hirose, Takehiro; Mitchell, Tom; di Toro, Giulio; Viti, Cecilia; Shimamoto, Toshiko

2010-05-01

During earthquake propagation in thermally unstable rocks, the frictional heat generated can induce thermal reactions which lead to chemical and physical changes in the slip zone. We performed laboratory friction experiments on thermally unstable minerals (gypsum, dolomite and calcite) at about 1 m/s slip velocities, more than 1 m displacements and calculated temperature rise above 500 C degrees. These conditions are typical during the propagation of large earthquakes. The main findings of our experimental work are: 1) Dramatic fault weakening is characterized by a dynamic frictional strength drop up to 90% of the initial static value in the Byerlee's range. 2) Seismic source parameters, calculated from our experimental results, match those obtained by modelling of seismological data from the 1997 Cofliorito earthquake nucleated in carbonate rocks in Italy (i.e. same rocks used in the friction experiments). Fault lubrication observed during the experiments is controlled by the superposition of multiple, thermally-activated, slip weakening mechanisms (e.g., flash heating, thermal pressurization and nanoparticle lubrication). The integration of mechanical and CO2 emission data, temperature rise calculations and XRPD analyses suggests that flash heating is not the main dynamic slip weakening process. This process was likely inhibited very soon (t < 1s) for displacements d < 0.20 m, when intense grain size reduction by both cataclastic and chemical/thermal processes took place. Conversely, most of the dynamic weakening observed was controlled by thermal pressurization and nanoparticle lubrication processes. The dynamic shear strength of experimental faults was reduced when fluids (CO2, H2O) were trapped and pressurized within the slip zone, in accord with the effective normal stress principle. The fluids were not initially present in the slip zone, but were released by decarbonation (dolomite and Mg-rich calcite) and dehydration (gypsum) reactions, both activated by frictional heating during seismic slip. The dynamic weakening effects of nanoparticles (e.g. powder lubrication) are still unclear due to the poorly understood mechanical properties of nanoparticles at high velocities and temperatures, typical of seismic slip. The experimental results improve our understanding of the controls exerted on the dynamic frictional strength of faults by the coseismic operation of chemical (mineral decomposition) and physical (grain size reduction, fluids release and pressurization) processes. The estimation of this parameter is out of the range of seismological studies, although it controls the magnitude of the stress drop, the seismic fault heat flow and the relative partitioning of the earthquake energy budget, which are all controversial and still debated issues in the scientific community.

Fault Lubrication and Earthquake Propagation in Thermally Unstable Rocks

NASA Astrophysics Data System (ADS)

de Paola, N.; Hirose, T.; Mitchell, T. M.; di Toro, G.; Viti, C.; Shimamoto, T.

2009-12-01

During earthquake propagation in thermally unstable rocks, the frictional heat generated can induce thermal reactions which lead to chemical and physical changes in the slip zone. We performed laboratory friction experiments on thermally unstable minerals (gypsum, dolomite and calcite) at about 1 m/s slip velocities, more than 1 m displacements and calculated temperature rise above 500 C degrees. These conditions are typical during the propagation of large earthquakes. The main findings of our experimental work are: 1) Dramatic fault weakening is characterized by a dynamic frictional strength drop up to 90% of the initial static value in the Byerlee’s range. 2) Seismic source parameters, calculated from our experimental results, match those obtained by modelling of seismological data from the 1997 Cofliorito earthquake nucleated in carbonate rocks in Italy (i.e. same rocks used in the friction experiments). Fault lubrication observed during the experiments is controlled by the superposition of multiple, thermally-activated, slip weakening mechanisms (e.g., flash heating, thermal pressurization and nanoparticle lubrication). The integration of mechanical and CO2 emission data, temperature rise calculations and XRPD analyses suggests that flash heating is not the main dynamic slip weakening process. This process was likely inhibited very soon (t < 1s) for displacements d < 0.20 m, when intense grain size reduction by both cataclastic and chemical/thermal processes took place. Conversely, most of the dynamic weakening observed was controlled by thermal pressurization and nanoparticle lubrication processes. The dynamic shear strength of experimental faults was reduced when fluids (CO2, H2O) were trapped and pressurized within the slip zone, in accord with the effective normal stress principle. The fluids were not initially present in the slip zone, but were released by decarbonation (dolomite and Mg-rich calcite) and dehydration (gypsum) reactions, both activated by frictional heating during seismic slip. The dynamic weakening effects of nanoparticles (e.g. powder lubrication) are still unclear due to the poorly understood mechanical properties of nanoparticles at high velocities and temperatures, typical of seismic slip. The experimental results improve our understanding of the controls exerted on the dynamic frictional strength of faults by the coseismic operation of chemical (mineral decomposition) and physical (grain size reduction, fluids release and pressurization) processes. The estimation of this parameter is out of the range of seismological studies, although it controls the magnitude of the stress drop, the seismic fault heat flow and the relative partitioning of the earthquake energy budget, which are all controversial and still debated issues in the scientific community.

BECCS Market Launch Strategy Aiming to Help Ensure Reliable Grid Power at High Penetrations of IRE (Intermittent Renewable Electricity)

NASA Astrophysics Data System (ADS)

WIlliams, R. H.

2017-12-01

Despite its recognized importance for carbon (C)-mitigation, progress in advancing biomass energy with CO2 capture and sequestration (BECCS) has been slow. A BECCS market launch strategy based on technologies ready for commercial-scale demonstration is discussed—based on co-gasification of coal and biomass to make H2 with CCS. H2 so produced would be a key element of a H2 balancing capacity (H2-BC) strategy for ensuring reliable grid power at high IRE penetrations. High grid penetrations of IRE must be complemented by fast-ramping balancing (backup and/or storage) capacity (BC) to ensure reliable grid power. BC provided now by natural gas-fired gas turbine combined cycle and combustion turbine units would eventually have to be decarbonized to realize C-mitigation goals, via CCS or other means. Capital-intensive CCS energy systems require baseload operation to realize favourable economics, but at high IRE penetrations, BC plants must be operated at low capacity factors. A H2-BC strategy is a promising way to address this challenge. The elements of a H2-BC system are: (a) H2 production from carbonaceous feedstocks in baseload plants with CCS; (b) H2 consumption in fast-ramping BC units that operate at low capacity factors; (c) Buffer underground H2 storage to enable decoupling baseload H2 production from highly variable H2 consumption by BC units. The concept is likely to "work" because underground H2 storage is expected to be inexpensive. A H2 production analysis is presented for a negative GHG-emitting H2-BC system based on cogasification of corn stover and coal, with captured CO2 used for enhanced oil recovery. The technical readiness of each system component is discussed, and preliminary insights are offered as to the conditions under which the corresponding H2-BC system might compete with natural gas in providing backup for IRE on US electric grids. Public policy to help advance this strategy might be forthcoming, because 2 US Senate bills with broad bipartisan support might become law soon: (a) S.1535, which extends and expands 45Q tax credits for CO2 EOR; and (b) S.1460. Inter alia, S.1460 authorizes DOE to spend $22 million/year during 2018-2022 to support of Front End Engineering and Design studies for net-negative CO2 emissions projects based on thermochemical coal/biomass coprocessing with CCS.

A thermoanalytical, X-ray diffraction and petrographic approach to the forensic assessment of fire affected concrete in the United Arab Emirates.

PubMed

Alqassim, M A; Jones, M R; Berlouis, L E A; Nic Daeid, N

2016-07-01

For most fires, forensic investigation takes place well after building materials have cooled and knowledge of the structural damage due to heat exposure can reveal the temperature reached during an incident. Recently, there have been significant changes in the types and hence characteristics of cementitious materials used in the United Arab Emirates. Few studies focus on the application of thermo-analytical, X-ray diffraction and petrographic techniques on newly developed structures and this work aims to address this deficiency by utilising a series of parametric laboratory-based tests to assess the effects of heat on hardened concrete. Specimens were made with a design mix typically used for low-rise residential homes and storage facilities. The key constituents were: Portland cement (PC), crushed gabbro stone and dune sand with water/cement ratios of 0.4-0.5. Portland cement substitutes included ground granulated blast-furnace slag (GGBS), and silica fume (SF) at replacement percentages of up to 50% and 4%, respectively. The concrete cubes of 100-mm size were produced and standard cured to 28 days and then exposed to heat inside an electric furnace with pre-determined temperature regimes of 150°C, 300°C, 600°C and 900°C. Petrographic examination was utilised to compare the discolouration of the cooled concrete. Data derived from thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) are reported in order to assess the usefulness of these techniques in fire scene investigation to differentiate between these temperature regimes. The results from the TGA indicate that the majority of the percentage weight loss for all the mixtures occurred in the range 650-700°C, which corresponds to the decarbonation of calcium carbonate, mainly from the aggregates. The endothermic DSC peak at 70-120°C relates to the loss of evaporable water. Since both of these reactions are irreversible, this information can help fire investigators estimate the temperature history of concrete after exposure to fire. On the other hand, the portlandite in the cement matrix dehydroxylates at 450-550°C but then reforms as the concrete cools. The onset temperature for the dehydroxylation of the reformed mineral is always lower than in virgin samples and its enthalpy furthermore depends strongly on the thermal history of the portlandite. Thus, this feature can be used to establish the temperature to which the material was exposed to during a fire incident. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Policy Needs for Carbon Capture & Storage

NASA Astrophysics Data System (ADS)

Peridas, G.

2007-12-01

Climate change is one of the most pressing environmental problems of our time. The widespread consensus that exists on climate science requires deep cuts in greenhouse gas emissions, on the order of 50-80% globally from current levels. Reducing energy demand, increasing energy efficiency and sourcing our energy from renewable sources will, and should, play a key role in achieving these cuts. Fossil fuels however are abundant, relatively inexpensive, and still make up the backbone of our energy system. Phasing out fossil fuel use will be a gradual process, and is likely to take far longer than the timeframe dictated by climate science for reducing emissions. A reliable way of decarbonizing the use of fossil fuels is needed. Carbon capture and storage (CCS) has already proven to be a technology that can safely and effectively accomplish this task. The technological know-how and the underground capacity exist to store billions of tons of carbon dioxide in mature oil and gas fields, and deep saline formations. Three large international commercial projects and several other applications have proved this, but substantial barriers remain to be overcome before CCS becomes the technology of choice in all major emitting sectors. Government has a significant role to play in surmounting these barriers. Without mandatory limits on greenhouse gas emissions and a price on carbon, CCS is likely to linger in the background. The expected initial carbon price levels and their potential volatility under such a scheme dictates that further policies be used in the early years in order for CCS to be implemented. Such policies could include a new source performance standard for power plants, and a low carbon generation obligation that would relieve first movers by spreading the additional cost of the technology over entire sectors. A tax credit for capturing and permanently sequestering anthropogenic CO2 would aid project economics. Assistance in the form of loan guarantees for components of the technology that make financing problematic due to insufficient performance guarantees would help first movers. The development of a pipeline network for transporting CO2 will require centralized planning in order to materialize and make use of economies of scale. The federal government should significantly accelerate its research, development and demonstration program, with particular emphasis on multi-megaton injections in representative geological settings. Finally, a comprehensive regulatory framework for large-scale injections is a high priority item that can and should be developed now, with scope for revision after our experience with CCS projects grows.

A grain of sand or a handful of dust?

NASA Astrophysics Data System (ADS)

Wagner, Fabian

2013-03-01

The recent paper by Girod et al (2013) analyses the implications of stringent global GHG mitigation targets for the intensities of, inter alia , broad consumption categories like food, shelter and transport. This type of scenario modeling analysis and inverse reasoning helps us to better understand the potential or required contribution of changes in consumption patterns to mitigation. This is welcome because while there is a growing literature on the behavioral and consumption dimensions of mitigation, there is still no widely accepted framework for studying systematically the interactions between supply and demand, behavior and technology, production and consumption. So we are left with the question: what do we need to do exactly to stabilize GHG concentrations? Intuitively, we take our cue from Aristotelian logic: if A implies B, then in order to avoid B we had better prevent A. At this level it is clear that we need either to decarbonize our energy systems to start with, or to suck out CO2 from the atmosphere. When multiple causes are at work, however, our neat Aristotelian picture is no longer appropriate (Cartwright 2003). Leaving capturing and storage aside, we need to decarbonize our systems, but we also need to reduce the energy intensity, change our personal habits, eat less meat, use more public transportation, etc. What is the right balance between these factors? Can we do just one thing, say, eat less meat, but not another, and still achieve some pretty ambitious mitigation goals? In other words, what are necessary and what are sufficient sets of measures to reach these goals? Let us first look at the question of necessary measures. This gets tricky when applied to individual consumers: it is somewhat akin to the notorious question whether a heap of sand is still a heap when you take away one grain (Sainsbury 2011). If you are inclined to say yes, think once more. What happens when you take away another one, and another one, and another one, and so forth? Eventually you are forced call a single grain a heap. By a similar type of reasoning none of us consumers makes any difference individually. It is tempting to conclude that therefore consumption side mitigation is not sufficient. But it also does not really seem necessary in the strict sense of the word as long as some supply side measure can compensate for a demand side measure not taken. Thus each one of us could go on as before, as long as someone else or some technology is compensating for our own failure to change. To be sure, such elusive argument is, to say the least, not very helpful, but it highlights the difficulty to derive very specific courses of action from aggregate goals. So it takes a more prescriptive approach to get things going. The pragmatic mitigation wedge analysis by, e.g., Pacala and Socolow (2004) has highlighted that a relatively small number of dedicated and practicable measures is sufficient to achieve deep emission cuts, but the balance of these measures in the analyses is understandably somewhat arbitrary. Other analysis, based on Integrated Assessment Models (IAMs) has focused more specifically on the questions of where and when measures would be implemented in the most cost-effective manner. From such studies one can learn about carbon price trajectories, technology diffusion rates, and possibly about conditional probabilities for reaching targets over time. However, IAMs are rarely used to assess systematically the necessary or sufficient conditions for reaching a given target, and when they do the outcome often is—with the occasional exception—disappointingly generic. Moreover, the controversies arising from value-laden allocations derived from IAMs are well-known: in these models emissions are typically reduced where it (supposedly) can be done cheapest, i.e. in low-wage countries, or according to some burden sharing scheme. The allocation of mitigation over time is essentially determined by the magnitude of the discount rate and thus a valuation of future versus present expenditures. Refreshingly, Girod et al (2013) discuss a selection of allocation schemes across sectors, including consumers, that allow us to get an impression of the requirements and bounds for each of a set of stylized demand activities within the context of a plausible overall IAM story. Thus Girod et al (2013), make progress in addressing consumer behavior in the context of a wider set of activities contributing to GHG emissions and technological options to reduce these, without being committed to any particular allocation scheme. Further work will have to address issues raised by a recent study (Schweizer and Kriegler 2012) on the limitations of the scenario space in earlier IPCC assessments to avoid past omissions. Moreover, IAMs in general need to become more transparent and more responsive to the needs of stakeholders. They also need to be applied specifically to identify concrete incentives, such as co-benefits of mitigation (Wagner 2012) and mechanisms (beyond stylized carbon markets) that nudge us towards low emission pathways. References Cartwright N 2003 Hunting Causes and Using Them: Approaches in Philosophy and Economics 1st edn (Cambridge: Cambridge University Press) Girod B, Van Vuuren D P and Hertwich E G 2013 Global climate targets and future consumption level: an evaluation of the required GHG intensity Environ. Res. Lett. 8 014016 Pacala S and Socolow R 2004 Stabilization wedges: solving the climate problem for the next 50 years with current technologies Science 305 968-72 Sainsbury R M 2011 Paradoxes 3rd edn (Cambridge: Cambridge University Press) Schweizer V J and Kriegler E 2012 Improving environmental change research with systematic techniques for qualitative scenarios Environ. Res. Lett. 7 044011 Wagner F 2012 Mitigation here and now or there and then: the role of co-benefits Carbon Manag. 3 325-7

Energy, Environmental, and Economic Analyses of Design Concepts for the Co-Production of Fuels and Chemicals with Electricity via Co-Gasification of Coal and Biomass

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

Eric Larson; Robert Williams; Thomas Kreutz

2012-03-11

The overall objective of this project was to quantify the energy, environmental, and economic performance of industrial facilities that would coproduce electricity and transportation fuels or chemicals from a mixture of coal and biomass via co-gasification in a single pressurized, oxygen-blown, entrained-flow gasifier, with capture and storage of CO{sub 2} (CCS). The work sought to identify plant designs with promising (Nth plant) economics, superior environmental footprints, and the potential to be deployed at scale as a means for simultaneously achieving enhanced energy security and deep reductions in U.S. GHG emissions in the coming decades. Designs included systems using primarily already-commercializedmore » component technologies, which may have the potential for near-term deployment at scale, as well as systems incorporating some advanced technologies at various stages of R&D. All of the coproduction designs have the common attribute of producing some electricity and also of capturing CO{sub 2} for storage. For each of the co-product pairs detailed process mass and energy simulations (using Aspen Plus software) were developed for a set of alternative process configurations, on the basis of which lifecycle greenhouse gas emissions, Nth plant economic performance, and other characteristics were evaluated for each configuration. In developing each set of process configurations, focused attention was given to understanding the influence of biomass input fraction and electricity output fraction. Self-consistent evaluations were also carried out for gasification-based reference systems producing only electricity from coal, including integrated gasification combined cycle (IGCC) and integrated gasification solid-oxide fuel cell (IGFC) systems. The reason biomass is considered as a co-feed with coal in cases when gasoline or olefins are co-produced with electricity is to help reduce lifecycle greenhouse gas (GHG) emissions for these systems. Storing biomass-derived CO{sub 2} underground represents negative CO{sub 2} emissions if the biomass is grown sustainably (i.e., if one ton of new biomass growth replaces each ton consumed), and this offsets positive CO{sub 2} emissions associated with the coal used in these systems. Different coal:biomass input ratios will produce different net lifecycle greenhouse gas (GHG) emissions for these systems, which is the reason that attention in our analysis was given to the impact of the biomass input fraction. In the case of systems that produce only products with no carbon content, namely electricity, ammonia and hydrogen, only coal was considered as a feedstock because it is possible in theory to essentially fully decarbonize such products by capturing all of the coal-derived CO{sub 2} during the production process.« less

Role of fluids in experimental calcite-bearing faults at seismic deformation conditions.

NASA Astrophysics Data System (ADS)

Violay, M.; Nielsen, S.; Cinti, D.; Spagnuolo, E.; Di Toro, G.; Smith, S.

2012-04-01

Fluids play a fundamental physical (fluid pressure, temperature buffering, etc.) and chemical (dissolution, hydrolytic weakening, etc.) role in controlling fault strength and earthquake nucleation, propagation and arrest. However, due to technical challenges, the influence of water at deformation conditions typical of earthquakes (i.e., slip rates of 1 m/s, displacements of 0.1-5 m, normal stress of tens of MPa) remains poorly constrained experimentally. Here we present results from high velocity friction experiments performed with a rotary shear apparatus (SHIVA: Slow to HIgh Velocity (friction) Apparatus) on Carrara marble. SHIVA is equipped with (1) an environmental/vacuum chamber to perform experiments in the absence of room-humidity, (2) a pressure vessel to perform experiments with fluids (up to 15 MPa confining pressure), including devices to determine fluid composition (Ca2+, Mg2+, HCO3-, etc). Experiments were conducted on hollow cylinders (50/30 mm ext/int diameter) of Carrara (98% calcite) marble at velocities of 1-6.5 m/s, displacements up to a few meters, normal stresses up to 40 MPa and fluid pressures between 0 (under vacuum) and 15 MPa (fluid-saturated conditions, with H2O in chemical equilibrium with the marble). Rock and fluid samples were recovered for post-run analysis to determine deformation mechanisms and changes in fluid composition. Under these deformation conditions: 1) the friction coefficient decays rapidly from a peak (= static) μp ~ 0.8 at the initiation of sliding towards a steady-state μss ~ 0.1. The absolute values of both peak and steady-state friction are not significantly influenced by the presence of fluids; 2) the decay from peak to steady-state friction is more abrupt in presence of fluids; 3) during deceleration of the friction apparatus, the friction coefficient recovers almost instantaneously to a value, μr, of 0.2-0.6 ( strength recovery) resulting in a small static stress drop. Strength recovery is smaller in the presence of fluids. 4) the fluid (H2O) after the experiment is enriched in Ca2+, Mg2+ and HCO3-. This chemical evolution suggests breakdown reactions (decarbonation of calcite) promoted by frictional heating and controlled by the presence of H2O. We conclude that the large decrease in friction and abrupt weakening, especially in the presence of fluids, indicates that calcite-bearing rocks are prone to earthquake nucleation and seismic rupture propagation (see the L'Aquila 2009 earthquake sequence). The chemical changes observed in water springs after large earthquakes in carbonatic rocks is similar to those found in these experiments, suggesting that the weakening mechanisms triggered in the experiments might occur in nature.

Subduction-Zone Metamorphic Pathway for Deep Carbon Cycling: Evidence from the Italian Alps and the Tianshan

NASA Astrophysics Data System (ADS)

Bebout, G. E.; Collins, N.; Cook-Kollars, J.; Angiboust, S.; Agard, P.; Scambelluri, M.; John, T.; Kump, L. R.

2013-12-01

Depending on the magnitude of the poorly constrained C flux in ultramafic rocks, on a global basis, sediments and altered oceanic crust (AOC) together deliver 70-95% of the C currently entering subduction zones. We are investigating extents of retention and metamorphic release of C in deeply subducted AOC and carbonate-rich sediment represented by HP/UHP meta-ophiolitic and metasedimentary rocks in the Italian Alps and in the Tianshan. Study of metapelite devolatilization in the same W. Alps suite (Bebout et al., 2013, Chem. Geol.) provides a geochemical framework for study of C behavior along prograde P-T paths similar to those experienced in forearcs of most modern subduction margins. Study of veins in the Tianshan affords examination of C mobility in UHP fluids, in later stages as metabasaltic rocks were fragmented in the subduction channel. Our results for sediments and AOC indicate impressive retention of oxidized C (carbonate) and reduced C (variably metamorphosed organic matter) to depths approaching those beneath arc volcanic fronts. In metasedimentary rocks, extensive isotopic exchange between the oxidized and reduced C resulted in shifts in both reservoirs toward upper mantle compositions. Much of the carbonate in metabasalts has C and O isotopic compositions overlapping with those for carbonate in AOC, with some HP/UHP metamorphic veins showing greater influence of organic C signatures from metasedimentary rocks. Calculations of prograde devolatilization histories using Perple-X demonstrate that, in most forearcs, very little decarbonation occurs in the more carbonate-rich rocks unless they are flushed by H2O-rich fluids from an external source, for example, from the hydrated ultramafic section of subducting slabs (cf. Gorman et al., 2006; G3) or from more nearby rocks experiencing dehydration (e.g., metapelites). A comparison of the most recently published thermal models for modern subduction zones (van Keken et al., 2011, JGR) with calculated and experimentally determined phase relations indicates that significant C loss during devolatilization (and partial melting) should occur as subducting sections traverse depths beneath arcs. The extent of C mobility due to carbonate dissolution remains uncertain. On a global basis, imbalance between subducted C input and C return flux by magmatism (excluding ultramafic inputs, ~40×20% of subducted C return via arcs and ~80×20% by all magmatism; Bebout, 2013, Treat. Geochem.) indicates net modern C return to the mantle, perhaps a reversal of Archean net outgassing (despite more rapid subduction). Global C cycle models predict that relatively small (and geologically plausible) change in the subduction/volcanic C flux could significantly affect atmospheric CO2 levels and thus global climate.

Looking into a volcanic area: An overview on the 350 m scientific drilling at Colli Albani (Rome, Italy)

NASA Astrophysics Data System (ADS)

Mariucci, M. Teresa; Pierdominici, Simona; Pizzino, Luca; Marra, Fabrizio; Montone, Paola

2008-09-01

A 350 m deep borehole was drilled in the Colli Albani volcanic district (Central Italy) in order to: understand the shallow crust structure beneath the volcanic complex; characterize the rock physical properties especially through in-situ measurements and, afterward, laboratory experiments; assess the local present-day stress field; install a broad-band seismometer at depth. The borehole is located adjacent to the western rim of the Tuscolano-Artemisio caldera, where several phenomena of unrest recently occurred. In 1989-90 a seismic swarm affected this area and a related uplift was recognized. In addition, high gas concentrations (mainly CO 2 and H 2S), in aquifers and soils, caused illnesses and casualties among inhabitants and animals in the past. We describe the investigations carried out at the drill site and the results achieved from data analysis. Wire-line drilling produced a complete stratigraphic record of the Quaternary volcanic units down to the Plio-Pleistocene sedimentary sequence and geophysical logs allowed a characterization of the rock physical properties. From a tectonic point of view, data provided by Dipmeter and Borehole Televiewer were used for investigations on the recent and present-day stress field and the results are compared to those available in the literature. In the volcanic units we recognized two main fracture systems, SW and NW dipping. Several faults intersecting the borehole show planes with oblique striae, indicating a prevalent strike-slip component of the movement. Finally, borehole breakout analysis defined an active stress field with a ˜ E-W oriented minimum horizontal component. At the end of the drilling, a blow-out occurred, due to pressurized fluids trapped into the sandy unit drilled in the last few meters of the hole. Sampling these fluids gave an additional value to the borehole, providing information about the deep volcanic circulation and its possible connection to a deep-seated magma chamber. The main results show water with a Na-HCO 3 chemistry and the highest salinity ever recognised in the area (Electrical Conductivity = 10.12 mS/cm). Stable O and H isotopes reveal a meteoric origin of water and the absence of tritium points out a long residence time in the aquifer. Emitted gas is CO 2-dominated, with N 2 as second most important component. Helium isotopic composition of the gas allows us to estimate a magmatic component ranging in the interval 40-50%, one of the highest in the Colli Albani. Carbon isotopes of CO 2 (- 0.53‰ vs. PDB) suggest that it could derive partly from a magmatic source and partly by the thermal decarbonation of the carbonatic basement.

Fluid regimes during late stages of a continental collision: Physical, chemical, and stable isotope measurements of fluid inclusions in fissure quartz from a geotraverse through the Central Alps, Switzerland

NASA Astrophysics Data System (ADS)

Mullis, Josef; Dubessy, Jean; Poty, Bernard; O'Neil, James

1994-05-01

Fluid evolution during neo-alpine metamorphism during late stages of the continental collision between Europe and Africa was studied by analyzing fluid inclusions in alpine fissure quartz collected in forty-nine localities along a geotraverse through the Central Alps, Switzerland. The methods employed include microthermometry, micro-Raman spectroscopy, K/Na thermometry, and stable isotope analysis. Early fluid inclusions provide evidence of close to peak metamorphic temperatures of the late Tertiary or neo-alpine metamorphic event. Fluid composition evolved along the geotraverse from north to south as follows: higher hydrocarbons were dominant in the low- and medium-grade diagenetic zones, methane was the main volatile in the high-grade diagenetic and low-grade anchizone, water dominated in the highgrade anchizone and low-grade epizone, with CO2 > 10 mol% in the high-grade epizone and in the mesozone. Higher hydrocarbons and CH 4 were the products of kerogen maturation and cracking of preexisting petroleum. Large water supplies originated from the dehydration of cooler metasedimentary rocks that were overthrust by crystalline basements of the Lepontines, Aar, and Gotthard massifs. Carbon isotope analyses suggest that the CO 2 component was derived from oxidation of graphitic matter, especially in the vicinity of sulfate-bearing metasediments and from decarbonation reactions. In the Aar and Gotthard massifs as well as in the Helvetic Axen nappe and its underlying North Helvetic flysch, high fluid pressures prevailed and favored nappe transport. By contrast, in the southern Lepontine area, very low early fluid pressures were probably related to dry rocks and scarce metasediments, and to high geothermal gradients that resulted from intense uplift and erosion between 26 and 18 Ma. Retrograde fluid evolution was recorded by a succession of fluid inclusion populations in each alpine fissure. It was controlled by uplift and cooling and characterized by decreasing contents of volatiles and an increase in δ 18O of host quartz. Tectonic activity led to episodic pressure drops of at least 0.5 to 2 kbar and promoted fluid unmixing, channelized flow, and rapid growth of skeletal quartz. Channelized rather than pervasive fluid migration at temperatures < 450° C and under conditions of brittle deformation is documented by episodic increases in salinity and by fluid flushing through the massifs. There is stable isotope evidence for involvement of meteoric water only in late-crystallizing quartz. Formation of Alpine fissures and fissure minerals was the result of a unique coincidence of late continental collision (< 450° C), fluid expulsion from overthrust metasediments, uplift, and erosion.

An early warning system for high climate sensitivity? (Invited)

NASA Astrophysics Data System (ADS)

Pierrehumbert, R.

2010-12-01

The scientific case for the clear and present danger of global warming has been unassailable at least since the release of the Charney Report more than thirty years ago, if not longer. While prompt action to begin decarbonizing energy systems could still head off much of the potential warming, it is distinctly possible that emissions will continue unabated in the coming decades, leading to a doubling or more of pre-industrial carbon dioxide concentrations. At present, we are in the unenviable position of not even knowing how bad things will get if this scenario comes to pass, because of the uncertainty in climate sensitivity. If climate sensitivity is high, then the consequences will be dire, perhaps even catastrophic. As the world continues to warm in response to continued carbon dioxide emissions, will we at least be able to monitor the climate and provide an early warning that the planet is on a high-sensitivity track, if such turns out to be the case? At what point will we actually know the climate sensitivity? It has long been recognized that the prime contributor to uncertainty in climate sensitivity is uncertainty in cloud feedbacks. Study of paleoclimate and climate of the past century has not been able to resolve which models do cloud feedback most correctly, because of uncertainties in radiative forcing. In this talk, I will discuss monitoring requirements, and analysis techniques, that might have the potential to determine which climate models most faithfully represent climate feedbacks, and thus determine which models provide the best estimate of climate sensitivity. The endeavor is complicated by the distinction between transient climate response and equilibrium climate sensitivity. I will discuss the particular challenges posed by this issue, particularly in light of recent indications that the pattern of ocean heat storage may lead to different cloud feedbacks in the transient warming stage than apply once the system has reached equilibrium. Apart from this problem, the transient nature of climate response driven by increasing CO2 requires careful monitoring of ocean heat storage as well as top-of-atmosphere radiative budgets, if climate sensitivity is to be estimated. Water vapor feedback is not considered as uncertain as cloud feedback, but there is still a considerable potential for surprises. I will discuss microwave monitoring requirements for tracking water vapor feedback. At the other extreme, the longer term feedbacks that contribute to Earth System Sensitivity are even more uncertain than cloud feedbacks, particularly with regard to the terrestrial carbon cycle. Prospects for obtaining an early warning of a PETM-type organic carbon release seem bleak. Finally, I will discuss the particular challenge of obtaining an early warning of high climate sensitivity in the case that the climate system has a bifurcation.

Diffusion-controlled garnet growth in siliceous dolomites of the Adamello contact aureole, N-Italy

NASA Astrophysics Data System (ADS)

Muller, T.; Fiebich, E.; Foster, C. T.

2012-12-01

Texture forming processes are controlled by many factors, such as material transport through polycrystalline materials, surface kinetics, fluid flow, and many others. In metamorphic rocks, texture forming processes typically involve local reactions linked to net mass transfer which allows constraining the actual reaction path in more detail. In this study, we present geochemical data combined with textural modeling to constrain the conditions and reaction mechanism during contact metamorphic garnet growth in siliceous dolomites in the southern Adamello Massif, Italy. The metamorphic garnet porphyroblasts are poikiloblastic and idiomorphic in shape with a typical grain size ranging between 0.6-1 cm in diameter sitting in a matrix of calcite+diopside+anorthite+wollastonite. Inclusions in the grossular-rich garnets are almost uniquely diopside. On the hand specimen, garnets are surrounded by visible rims of about 0.6 mm indicating a diffusion-limited reaction mechanism to be responsible for the garnet formation. In the course of this study samples have been characterized by polarization microscopy, element x-ray maps using EMPA, cathodulominescence images and stable isotope analyses of carbon and oxygen of matrix carbonates. In addition, pseudosections have been calculated using the software package PerpleX (Connolly, 2005) based on the bulk chemistry of collected samples. Results indicate that the visible margin consists of a small rim (< 1 mm) purely consisting of recrystallized calcite adjacent to the garnet edge. The major part of the observed halo, however, is characterized by the absence of anorthite and wollastonite. The observed texture of garnet porphyroblasts growing and simultaneously forming an anorthite and wollastonite free margin can successfully be reproduced using the SEG program (Foster, 1993), which assumes diffusive mass transport. Therefore the model constrains the diffusive fluxes of Ca, Mg, Al and Si by mass balance and the local Gibbs-Duhem equations on the reaction site. Assuming that the pore fluid is not saturated in CO2, which is justified for the assumption of fluid-infiltration during contact metamorphism, the model predicts the wollastonite halo to be about the same size as the anorthite halo. Interestingly, the model also predicts the small diopside-free calcite margin surrounding the garnet interface, which is also observed in the thin section of the natural sample. Taken together, we interpret the garnet growth to be the consequence of the breakdown of anorthite + wollastonite + calcite at water-rich (XCO2 < 0.2) conditions around 600 °C. Preliminary modeling results suggest that the effective relative diffusion coefficients for Si, Mg and Al are not equal producing the diopside-free calcite rim surrounding the garnet edge. Connolly, J.A.D., 2005, Computation of phase equilibria by linear programming: A tool for geodynamic modeling and its application to subduction zone decarbonation. EPSL, 236 : p. 524-541. Foster, C.T., 1993, SEG93: A program to model metamorphic textures: Geological Society of America Abstracts with Programs, v. 25, no. 6, p. A264.

Pedo-sedimentary record of human-environment interaction in ditches and waterlogged depressions on tableland (roman and early medieval period) : micromorphological cases studies from Marne-la-Vallée area (Paris Basin, France)

NASA Astrophysics Data System (ADS)

Cammas, C.; Blanchard, J.; Broutin, P.; Berga, A.

2012-04-01

On lœss derived soils located on the Stampien plateau from the Paris Basin (France), archaeological anthroposols and ancient cultivated soils are only preserved in very few places. Recent archaeological excavations showed the presence of a pattern of roman ditches and waterlogged depressions (« mares ») under the actual cultivated horizon (Ap). This presence strongly suggests extensive past agricultural practices and water management. An original system of ditches was found Near Marne-la-Vallée (France). It is composed of two parts, one being large ditches characterized by flat bottom and sometimes water layered deposits, called « fossés collecteurs » by the archaeologists, and the orher being smaller ditches with colluvial deposits. Our objectives was to use archaeological and micromorphological studies in order to study i) the agricultural function of these ditches and depressions, ii) their evolution with time. Observations conducted on the infilling of a « fossé collecteur » at Bussy-Saint-Georges suggest that it was not part of a drainage system, but that it was a linear water controlled system, with a ramp in one part, and a basin or a tank in another, and that it was used for others anthropic activities. In the same area, a large waterlogged depression was studied, and micromorphological analysis helped to elucidate its pedo-sedimentary formation processes. At the bottom, massive silty clayey matrix retained water. Thin layers composed of silt and clay (indicating low energy flows and decantation), sometimes impregnated and hardened by iron, alternated with silty deposit (indicating higher ernergy water layered deposits). The thin, non porous and iron impregnated crusts helped to raise the depression level, as well as, most likely the water table during roman period, maintaining waterlogging conditions. At the beginning of the early medival period, a slightly peaty event was discriminated. Higher in the profile, in more redoxic conditions, ferruginous infilling of the microporosity and some vertic pedo-features alternated with higher energy deposits (fine sands). Some other important results are to be considered. The sedimentary matrix characteristics succession, a more calcareaous and lœss like sediments for the roman period and the beginning of the early medieval period, and a decarbonated matrix with clay, probably coming from the erosion of a luvisol, at the end of early medieval period. As a conclusion these elements show that two differents areas of the plateau were successively exploited. Furthermore, in all the profile, sedimentary and pedological features indicate successive water flows of variable intensity, wich could have been influenced by meteorological / climatical events, but our results suggest that they were more likely to have been controlled mainly by human activities, in connection with soils and ditch system management, especially during the early medieval period.

Friction of marble under seismic deformation conditions in the presence of fluids

NASA Astrophysics Data System (ADS)

Violay, M. E.; Nielsen, S. B.; Cinti, D.; Spagnuolo, E.; Di Toro, G.; Smith, S.

2011-12-01

Physical and chemical fluid/rock interactions control seismic rupture nucleation, propagation, arrest and recurrence. Several experimental studies explored the effects of pore fluid pressure (Pp) on the sliding behavior of faults. Most of them were performed with bi and tri-axial apparatus at high temperature and high confining pressure. However, due to the experimental configuration, laboratory measurements were limited in terms of slip rate (< 1 mm/s) and displacement (< 1 cm) compared to natural earthquakes (e.g., average slip rate about 1 m/s). Insight on the physical and chemical role of fluids during earthquakes can be gained using a rotary shear configuration which allows large displacements (nominally infinite) and seismic slip rates. Here we present results from the tests performed with SHIVA (Slow to HIgh Velocity Apparatus) equipped with a pore fluid vessel designed to reach 15 MPa of pore pressure on Carrara (98% calcite) marble. This rock was selected because most seismic ruptures in Italy propagate in fluid-rich (usually H2O and CO2), calcite-bearing fault zones (e.g. L'Aquila Mw 6.3, 2009 earthquake). Tests were conducted on hollow cylinders (50/30 mm ext/int diameter) at velocities of 1- 6.5 m/s, normal stresses up to 40 MPa and fluid (H2O in chemical equilibrium with the marble) pressure comprised between 0 (room-humidity conditions) and 15 MPa (fluid-saturated conditions). Fluid chemistry (Mg2+, Ca2+, HCO3-, pH, etc.) was determined before and after the experiments. Under these deformation conditions, the friction coefficient decays exponentially from a peak (= static) μp~ 0.8 at the initiation of sliding towards a steady-state μss~ 0.1. Once sliding stops, the friction coefficient recovers almost instantaneously a coefficient of friction μf = 0.2-0.6 (fault healing). The experimental data suggest that: 1) μp and μss are independent of the presence of fluids for a given imposed effective stress (σneff = σn- Pp = 10 MPa); 2) though μp and μss are similar for experiments performed under the same effective normal stress under room-humidity (σneff = σn= 10 MPa) and fluid-saturated conditions (σneff = σn- Pp =10 MPa), a comparison of the friction coefficient vs. slip curves shows that the decay is more abrupt in the case of room-humidity experiments: the presence of H2O slightly buffers dynamic weakening during seismic slip; 3) sample shortens in the presence of fluids and under room-humidity conditions; 4) fault healing is smaller in the case of experiments performed in the presence of fluids; 5) the fluid (H2O) after the experiment is enriched in Mg2+ and HCO3-: this chemical evolution suggest breakdown reactions (decarbonation of calcite) in the presence of H2O as observed in springs after some large earthquakes in carbonate rocks.

Elevated carbon dioxide flux at the Dixie Valley geothermal field, Nevada; relations between surface phenomena and the geothermal reservoir

USGS Publications Warehouse

Bergfeld, D.; Goff, F.; Janik, C.J.

2001-01-01

In the later part of the 1990s, a large die-off of desert shrubs occurred over an approximately 1 km2 area in the northwestern section of the Dixie Valley (DV) geothermal field. This paper reports results from accumulation-chamber measurements of soil CO2 flux from locations in the dead zone and stable isotope and chemical data on fluids from fumaroles, shallow wells, and geothermal production wells within and adjacent to the dead zone. A cumulative probability plot shows three types of flux sites within the dead zone: Locations with a normal background CO2 flux (7 g m-2 day-1); moderate flux sites displaying "excess" geothermal flux; and high flux sites near young vents and fumaroles. A maximum CO2 flux of 570 g m-2 day-1 was measured at a location adjacent to a fumarole. Using statistical methods appropriate for lognormally distributed populations of data, estimates of the geothermal flux range from 7.5 t day-1 from a 0.14-km2 site near the Stillwater Fault to 0.1 t day-1 from a 0.01 -km2 location of steaming ground on the valley floor. Anomalous CO2 flux is positively correlated with shallow temperature anomalies. The anomalous flux associated with the entire dead zone area declined about 35% over a 6-month period. The decline was most notable at a hot zone located on an alluvial fan and in the SG located on the valley floor. Gas geochemistry indicates that older established fumaroles along the Stillwater Fault and a 2-year-old vent in the lower section of the dead zone discharge a mixture of geothermal gases and air or gases from air-saturated meteoric water (ASMW). Stable isotope data indicate that steam from the smaller fumaroles is produced by ??? 100??C boiling of these mixed fluids and reservoir fluid. Steam from the Senator fumarole (SF) and from shallow wells penetrating the dead zone are probably derived by 140??C to 160??C boiling of reservoir fluid. Carbon-13 isotope data suggest that the reservoir CO2 is produced mainly by thermal decarbonation of hydrothermal calcite in veins that cut reservoir rocks. Formation of the dead zone is linked to the reservoir pressure decline caused by continuous reservoir drawdown from 1986 to present. These reservoir changes have restricted flow and induced boiling in a subsurface hydrothermal outflow plume extending from the Stillwater Fault southeast toward the DV floor. We estimate that maximum CO2 flux in the upflow zone along the Stillwater Fault in 1998 was roughly seven to eight times greater than the pre-production flux in 1986. The eventual decline in CO2 flux reflects the drying out of the outflow plume. Published by Elsevier Science B.V.

Seawater and Detrital Marine Pb Isotopes as Monitors of Antarctic Weathering Following Ice Sheet Development

NASA Astrophysics Data System (ADS)

Fenn, C.; Martin, E. E.; Basak, C.

2011-12-01

Comparisons of seawater and detrital Pb isotopes from sites proximal to Antarctica at the Eocene/Oligocene transition (EOT) are being used to understand variations in continental weathering associated with the development of the East Antarctic Ice Sheet (EAIS). Previous work has shown that seawater and detrital archives yield similar isotopic values during Eocene warmth, which is interpreted to record congruent chemical weathering of the continent. In contrast, distinct isotopic values for the two phases at the EOT represents increased incongruent mechanical weathering during growth of the ice sheet. For this study we expanded beyond the initial glaciation at the EOT to determine whether less dramatic changes in ice volume and climate also produce variations in weathering and intensity that are recorded by seawater and detrital Pb isotopes. We collected Nd and Pb isotope data from extractions of Fe-Mn oxide coatings of bulk decarbonated marine sediments, which preserve seawater isotopic values, and from complete dissolutions of the remaining silicate fraction for Ocean Drilling Program Site 748 on Kerguelen Plateau (1300 m modern water depth). The data spans an interval of deglaciation from ~23.5-27 Ma documented by δ18O that has been equated to a ~30% decrease in ice volume on Antarctica (Pekar and Christie-Blick, 2008, Palaeogeogr., Palaeoclim., Palaeoecol.). Initial results from Site 748 include the first ɛNd values for intermediate waters in the Oligocene Southern Ocean and reveal a value of ~-8 over the entire 3.5 my interval, which is consistent with values reported for deep Indian Ocean sites at this time and similar to deeper Southern Ocean sites. Corresponding detrital ɛNd values are less radiogenic and decrease from -9 to -13 during the study interval. Detrital 206Pb/204Pb values also decrease during the warming interval, while seawater 206Pb/204Pb values increase. The decrease in detrital values indicates the composition of source materials entering the ocean changed as the ice sheet waned. Increasing seawater 206Pb/204Pb may record enhanced chemical weathering under conditions of greater water availability and warmer temperatures combined with abundant rock flour created during the preceding glacial advance. As previous studies have documented initial weathering leachates tend to be more radiogenic than the parent rock composition. Alternatively, seawater values during warming in the late Oligocene approach values recorded during initial ice sheet expansion at the EOT in Site 738, which may suggest Pb isotope variations in seawater and detrital residues are not sensitive to less dramatic intervals of climate change and ice sheet dynamics. We plan to continue this study into the Pliocene to see if we can identify the timing of the transition from a wet-based to dry-based EAIS, an event that is likely to have profound consequences for weathering on Antarctica and the offset between the two Pb isotope archives.

Reconstruction of the Nd isotope composition of seawater on epicontinental seas: Testing the potential of Fe-Mn oxyhydroxide coatings on foraminifera tests for deep-time investigations

NASA Astrophysics Data System (ADS)

Charbonnier, Guillaume; Pucéat, Emmanuelle; Bayon, Germain; Desmares, Delphine; Dera, Guillaume; Durlet, Christophe; Deconinck, Jean-François; Amédro, Francis; Gourlan, Alexandra T.; Pellenard, Pierre; Bomou, Brahimsamba

2012-12-01

The Fe-Mn oxide fraction leached from deep-sea sediments has been increasingly used to reconstruct the Nd isotope composition of deep water masses, that can be used to track changes in oceanic circulation with a high temporal resolution. Application of this archive to reconstruct the Nd isotope composition of bottom seawater in shallow shelf environments remained however to be tested. Yet as the Nd isotope composition of seawater on continental margins is particularly sensitive to changes in erosional inputs, establishment of neritic seawater Nd isotope evolution around areas of deep water formation would be useful to discriminate the influence of changes in oceanic circulation and in isotopic composition of erosional inputs on the Nd isotope record of deep waters. The purpose of this study is to test the potential of Fe-Mn coatings leached from foraminifera tests to reconstruct the Nd isotope composition of seawater in shelf environments for deep-time intervals. Albian to Turonian samples from two different outcrops have been recovered, from the Paris Basin (Wissant section, northern France) and from the Western Interior Seaway (Hot Spring, South Dakota, USA), that were deposited in epicontinental seas. Rare Earth Element (REE) spectra enriched in middle REEs in the foraminifera leach at Wissant highlight the presence of Fe-Mn oxides. The similarity of the Nd isotopic signal of the Fe-Mn oxide fraction leached from foraminifera tests with that of fish teeth suggests that Fe-Mn oxides coating foraminifera can be good archives of shelf bottom seawater Nd isotopic composition. Inferred bottom shelf water Nd isotope compositions at Wissant range from -8.5 to -9.7 ɛ-units, about 1.5-2 ɛ-units higher than that of the contemporaneous local detrital fraction. At Hot Spring, linear REE spectra characterizing foraminifera leach may point to an absence of authigenic marine Fe-Mn oxide formation in this area during the Late Cenomanian-Early Turonian, consistent with dysoxic to anoxic conditions at Hot Spring, contemporaneous to an Oceanic Anoxic Event. The similarity of the Nd isotopic signal of the carbonate matrix of foraminifera with that of fish teeth suggests that it records the Nd isotope composition of bottom shelf seawater as well. Inferred bottom shelf water Nd isotope compositions at Hot Spring are quite radiogenic, between -7 and -6 ɛ-units, about 2.5-4 ɛ-units higher than that of the contemporaneous local detrital fraction. In contrast, in both sections Fe-Mn oxides leached directly from the decarbonated sediment tend to yield a less radiogenic Nd isotopic composition, typically between 0.2 and 0.8 ɛ-units lower, that is intermediate between that of fish teeth and of the detrital fraction. This suggests the contribution of pre-formed continental Fe-Mn oxides to the Nd isotopic signal, along with authigenic marine oxides, or a detrital contamination during leaching.

Oxygen isotope composition of mafic magmas at Vesuvius

NASA Astrophysics Data System (ADS)

Dallai, L.; Cioni, R.; Boschi, C.; D'Oriano, C.

2009-12-01

The oxygen isotope composition of olivine and clinopyroxene from four plinian (AD 79 Pompeii, 3960 BP Avellino), subplinian (AD 472 Pollena) and violent strombolian (Middle Age activity) eruptions were measured to constrain the nature and evolution of the primary magmas of the last 4000 years of Mt. Vesuvius activity. A large set of mm-sized crystals was accurately separated from selected juvenile material of the four eruptions. Crystals were analyzed for their major and trace element compositions (EPMA, Laser Ablation ICP-MS), and for 18O/16O ratios. As oxygen isotope composition of uncontaminated mantle rocks on world-wide scale is well constrained (δ18Oolivine = 5.2 ± 0.3; δ18Ocpx = 5.6 ± 0.3 ‰), the measured values can be conveniently used to monitor the effects of assimilation/contamination of crustal rocks in the evolution of the primary magmas. Instead, typically uncontaminated mantle values are hardly recovered in Italian Quaternary magmas, mostly due to the widespread occurrence of crustal contamination of the primary magmas during their ascent to the surface (e.g. Alban Hills, Ernici Mts., and Aeolian Islands). Low δ18O values have been measured in olivine from Pompeii eruption (δ18Oolivine = 5.54 ± 0.03‰), whereas higher O-compositions are recorded in mafic minerals from pumices or scoria of the other three eruptions. Measured olivine and clinopyroxene share quite homogeneous chemical compositions (Olivine Fo 85-90 ; Diopside En 45-48, respectively), and represent phases crystallized in near primary mafic magmas, as also constrained by their trace element compositions. Data on melt inclusions hosted in crystals of these compositions have been largely collected in the past demonstrating that they crystallized from mafic melt, basaltic to tephritic in composition. Published data on volatile content of these melt inclusions reveal the coexistence of dissolved water and carbon dioxide, and a minimum trapping pressure around 200-300 MPa, suggesting that crystal growth possibly occurred during magma ascent from the source region or in a shallow reservoir at about 8-10 km depth. Recently, experimental data have suggested massive carbonate assimilation (up to about 20%) to derive potassic alkali magmas from trachybasaltic melts. Accordingly, the δ18O variability and the trace element contents of the studied minerals suggest possible contamination of primary melts by an O-isotope enriched, REE-poor contaminant like the limestone of Vesuvius basement. The δ18Oolivine and δ18Ocpx of the studied minerals define variable degrees of carbonate assimilation and magma crystallization for the different eruptions, and possibly within the same eruption, and show evidence of oxygen isotope equilibrium at high temperature. However, energy-constrained AFC model suggest that carbonate contamination was limited. On the basis of our data, we suggest that interaction between magma and a fluxing, decarbonation-derived CO2 fluid may be partly accounted for the measured O-isotope compositions.

The effects of metamorphism on iron mineralogy and the iron speciation redox proxy

NASA Astrophysics Data System (ADS)

Slotznick, Sarah P.; Eiler, John M.; Fischer, Woodward W.

2018-03-01

As the most abundant transition metal in the Earth's crust, iron is a key player in the planetary redox budget. Observations of iron minerals in the sedimentary record have been used to describe atmospheric and aqueous redox environments over the evolution of our planet; the most common method applied is iron speciation, a geochemical sequential extraction method in which proportions of different iron minerals are compared to calibrations from modern sediments to determine water-column redox state. Less is known about how this proxy records information through post-depositional processes, including diagenesis and metamorphism. To get insight into this, we examined how the iron mineral groups/pools (silicates, oxides, sulfides, etc.) and paleoredox proxy interpretations can be affected by known metamorphic processes. Well-known metamorphic reactions occurring in sub-chlorite to kyanite rocks are able to move iron between different iron pools along a range of proxy vectors, potentially affecting paleoredox results. To quantify the effect strength of these reactions, we examined mineralogical and geochemical data from two classic localities where Silurian-Devonian shales, sandstones, and carbonates deposited in a marine sedimentary basin with oxygenated seawater (based on global and local biological constraints) have been regionally metamorphosed from lower-greenschist facies to granulite facies: Waits River and Gile Mountain Formations, Vermont, USA and the Waterville and Sangerville-Vassalboro Formations, Maine, USA. Plotting iron speciation ratios determined for samples from these localities revealed apparent paleoredox conditions of the depositional water column spanning the entire range from oxic to ferruginous (anoxic) to euxinic (anoxic and sulfidic). Pyrrhotite formation in samples highlighted problems within the proxy as iron pool assignment required assumptions about metamorphic reactions and pyrrhotite's identification depended on the extraction techniques utilized. The presence of diagenetic iron carbonates in many samples severely affected the proxy even at low grade, engendering an interpretation of ferruginous conditions in all lithologies, but particularly in carbonate-bearing rocks. Increasing metamorphic grades transformed iron in carbonates into iron in silicate minerals, which when combined with a slight increase in the amount of pyrrhotite, drove the proxy toward more oxic and more euxinic conditions. Broad-classes of metamorphic reactions (e.g. decarbonation, silicate formation) occurred at distinct temperatures-pressures in carbonates versus siliciclastics, and could be either abrupt between metamorphic facies or more gradual in nature. Notably, these analyses highlighted the importance of trace iron in phases like calcite, which otherwise might not be included in iron-focused research i.e. ore-system petrogenesis, metamorphic evolution, or normative calculations of mineral abundance. The observations show that iron is mobile and reactive during diagenesis and metamorphism, and these post-depositional processes can readily overprint primary redox information held by iron speciation. However, in principle, additional mineralogical and petrographic approaches can be combined with iron speciation data to help untangle many of these post-depositional processes and arrive at more accurate estimates of paleoenvironmental redox conditions and processes, even for metamorphosed samples.

Interactions of fluid and gas movement and faulting in the Colorado Plateau, southeastern Utah

NASA Astrophysics Data System (ADS)

Shipton, Z. K.; Evans, J. P.; Kirschner, D.; Heath, J.; Williams, A.; Dockrill, B.

2002-12-01

The east-west and west-northwest striking Salt Wash and the Little Grand Wash normal faults in the Colorado Plateau of southeastern Utah emit large amounts of CO2 gas from abandon drill holes, springs and a hydrocarbon seep. The leakage of similar CO2 charged water has also occurred in the past as shown by large localized tufa deposits and horizontal veins along the fault traces. These deposits consist of thick tufa terraces and mound extending up to 50 meters from the fault damage zones. The faults cut a north plunging anticline of siltstones, shales, and sandstones, and the fault rocks are fine-grained with clay-rich gouge. The Little Grand Wash fault displaces these rocks approximately 290 m and the Salt Wash graben offsets rocks approximately 130 m; both faults extend at least to the top of the Pennsylvanian Paradox Formation, which contains thick salt horizons 1.5 - 2 km at depth. Well log, geologic surface and geochemical data indicate the CO2 reservoirs and sources have been cut by the faults at depth providing a conduit for the vertical migration of CO2 to the surface, but limited horizontal flow across the fault plane. Three- dimensional flow modals show how the faults damage zones permeability is adjacent to the faults and the leakage though the damage zones is localized near the regional anticlines fold axis. Analysis of the fluids emanating from the faults aims to locate the sources and determine the chemical evolutions of the fluids. δ2H and δ18O isotopic data show that the ground waters are meteoric and have not circulated deeply enough to experience an oxygen-isotope shift. δ13C data and PCO2 values indicate that the gas is external to the ground water systems (i.e., not from soil zone gas or dissolution of carbonate aquifer material alone). 3He/4He ratio 0.30 - 0.31 from springs and geysers indicate that the majority of the gas is crustally derived and contains a minimal component of mantle or magmatic gases. δ13C values of 4 to 5 per mil from the veins indicate the possible carbon sources of dissolution of isotopically heavy marine carbonates or the thermal decarbonization of carbonates. Thus, our conceptual model is that gases from 1.5 km or greater in the basin are migrate upwards along the faults and charge shallower ground water systems, where chemical exchange occurs during discharge at and near surface. The faults have been active since ~42 Ma, corresponding to the rapid uplift of the region. Fault-fluid interactions are likely trigged by salt movement at depth, and also in response to the modern state of stress, in which north-northeast extension of the area is caused by NNE-oriented σ 3, and that the faults may reflect a critcally stressed crust in the region.

Processes of high-T fluid-rock interaction during gold mineralization in carbonate-bearing metasediments: the Navachab gold deposit, Namibia

NASA Astrophysics Data System (ADS)

Dziggel, A.; Wulff, K.; Kolb, J.; Meyer, F. M.

2009-08-01

The Navachab gold deposit in the Damara belt of central Namibia is hosted by a near-vertical sequence of amphibolite facies shelf-type metasediments, including marble, calc-silicate rock, and biotite schist. Petrologic and geochemical data were collected in the ore, alteration halos, and the wall rock to evaluate transport of elements and interaction between the wall rock and the mineralizing fluid. The semi-massive sulfide lenses and quartz-sulfide veins are characterized by a complex polymetallic ore assemblage, comprising pyrrhotite, chalcopyrite, sphalerite, and arsenopyrite, native bismuth, gold, bismuthinite, and bismuth tellurides. Mass balance calculations indicate the addition of up to several orders of magnitude of Au, Bi, As, Ag, and Cu. The mineralized zones also record up to eightfold higher Mn and Fe concentrations. The semi-massive sulfide lenses are situated in the banded calc-silicate rock. Petrologic and textural data indicate that they represent hydraulic breccias that contain up to 50 vol.% ore minerals, and that are dominated by a high-temperature (T) alteration assemblage of garnet-clinopyroxene-K-feldspar-quartz. The quartz-sulfide veins crosscut all lithological units. Their thickness and mineralogy is strongly controlled by the composition and rheological behavior of the wall rocks. In the biotite schist and calc-silicate rock, they are up to several decimeters thick and quartz-rich, whereas in the marble, the same veins are only a few millimeters thick and dominated by sulfides. The associated alteration halos comprise (1) an actinolite-quartz alteration in the biotite schist, (2) a garnet-clinopyroxene-K-feldspar-quartz alteration in the marble and calc-silicate rock, and (3) a garnet-biotite alteration that is recorded in all rock types except the marble. The hydrothermal overprint was associated with large-scale carbonate dissolution and a dramatic increase in CO2 in the ore fluid. Decarbonation of wall rocks, as well as a low REE content of the ore fluid resulted in the mobilization of the REE, and the decoupling of the LREE from the HREE. The alteration halos not only parallel the mineralized zones, but may also follow up single layers away from the mineralization. Alteration is far more pronounced facing upward, indicating that the rocks were steep when veining occurred. The petrologic and geochemical data indicate that the actinolite-quartz- and garnet-clinopyroxene-K-feldspar-quartz alterations formed in equilibrium with a fluid (super-) saturated in Si, and were mainly controlled by the composition of the wall rocks. In contrast, the garnet-biotite alteration formed by interaction with a fluid undersaturated in Si, and was mainly controlled by the fluid composition. This points to major differences in fluid-rock ratios and changes in fluid composition during alteration. The alteration systematics and geometry of the hydrothermal vein system are consistent with cyclic fluctuations in fluid pressure during fault valve action.

Geochemistry of the furnace magnetite bed, Franklin, New Jersey, and the relationship between stratiform iron oxide ores and stratiform zinc oxide-silicate ores in the New Jersey highlands

USGS Publications Warehouse

Johnson, C.A.; Skinner, B.J.

2003-01-01

The New Jersey Highlands terrace, which is an exposure of the Middle Proterozoic Grenville orogenic belt located in northeastern United States, contains stratiform zinc oxide-silicate deposits at Franklin and Sterling Hill and numerous massive magnetite deposits. The origins of the zinc and magnetite deposits have rarely been considered together, but a genetic link is suggested by the occurrence of the Furnace magnetite bed and small magnetite lenses immediately beneath the Franklin zinc deposit. The Furnace bed was metamorphosed and deformed along with its enclosing rocks during the Grenvillian orogeny, obscuring the original mineralogy and obliterating the original rock fabrics. The present mineralogy is manganiferous magnetite plus calcite. Trace hydrous silicates, some coexisting with fluorite, have fluorine contents that are among the highest ever observed in natural assemblages. Furnace bed calcite has ??13C values of -5 ?? 1 per mil relative to Peedee belemnite (PDB) and ??18O values of 11 to 20 per mil relative to Vienna-standard mean ocean water (VSMOW). The isotopic compositions do not vary as expected for an original siderite layer that decarbonated during metamorphism, but they are consistent with nearly isochemical metamorphism of an iron oxide + calcite protolith that is chemically and minerlogically similar to iron-rich sediments found near the Red Sea brine pools and isotopically similar to Superior-type banded iron formations. Other magniferous magnite + calcite bodies occur at approximately the same stratigraphic position as far 50 km from the zinc deposits. A model is presented in which the iron and zinc deposits formed along the western edge of a Middle Proterozoic marine basin. Zinc was transported by sulfate-stable brines and was precipitated under sulfate-stable conditions as zincian carbonates and Fe-Mn-Zn oxides and silicates. Whether the zincian assemblages settled from the water column or formed by replacement reactions in shallowly buried sediments is uncertain. The iron deposits formed at interfaces between anoxic and oxygenated waters. The Furnace magnetite bed resulted from seawater oxidation of hydrothermally transported iron near a brine conduit. Iron deposits also formed regionally on the basin floor at the interface betveen anoxic deep waters and oxygenated shallower waters. These deposits include not only manganiferous magnetite + calcite bodies similar to the Furnace magnetite bed but also silicate-facies deposits that formed by iron oxide accumulation where detrital sediment was abundant. A basin margin model can be extended to Grenvillian stratiform deposits in the northwest Adirondacks of New York and the Mont Laurier basin of Quebec. In these areas iron deposits (pyrite or magnetite) are found basinward of marble-hosted sphalerite deposits, such as those in the Balmat-Edwards district. Whether the iron and zinc precipitated as sulfide assemblages or carbonate-oxide-silicate assemblages depended on whether sufficient organic matter or other reductants were available in local sediments or bottom waters to stabilize H2S.

Carbonate component reduces o,oEDDHA/Fe sorption on two-line ferrihydrite

NASA Astrophysics Data System (ADS)

Yunta, F.; Lucena, J. J.; Smolders, E.

2012-04-01

The o,oEDDHA/Fe is the most common and effective iron chelate used as fertilizer in calcareous soils. Several authors have reported that the anionic o,oEDDHA/Fe complex is adsorbed to soil components such as ferrihydrite. The bicarbonate anion may be a competing ion for this sorption, however no studies have yet identified the extent and mechanism of this interaction. The aim of this work was to study the carbonate (bicarbonate + carbonate) effect on EDDHA/Fe adsorption on two-line ferrihydrite. Two-line ferrihydrite was synthetized adding NaOH on a nitrate iron (III) solution up to a final pH to be 8.0 and allowing to age for 22 hours at 20°C. Dialyzed ferrihydrite was characterized by determining specific parameters such as Fe/OH ratio, BET surface, point zero of charge and x-ray diffraction. The sorption was performed at three pH levels (5, 7.5 and 9.5) and three initial carbonate concentrations (from 0 to 2 mM). Initial EDDHA/Fe, ferrihydrite and ionic strength concentrations were adjusted to 0.18 mM, 10 g L-1 and 5 mM respectively. Total dissolved FeEDDHA concentrations were quantified at 480 nm. The o,oEDDHA/Fe isomers (rac-o,oEDDHA/Fe and meso-o,oEDDHA/Fe) were separated and quantified by High Performance Liquid Chromatography (HPLC) fitting a photodiode array detector (PDA). Distribution factor (KD) and sorbed o,oEDDHA/Fe concentration were determined. Actual carbonate concentration was determined using a multi N/C analyzer. Ferrihydrite samples showed a typical XRD pattern of two-line ferrihydrite, two broad peaks at about 35 and 62° respectively. The BET surfaces (two replicates) were 259.2 ± 3.1 m2/g and 256.0 ± 2.5 m2/g. The Point Zero of Salt Effect (PZSE) was 7.9 ± 0.2 as bibliographically supported for all fresh and thus not rigorously de-carbonated ferrihydrite samples. The KD of the o,oEDDHA/Fe increased from 27.4 ± 0.6 to 304 ± 6 l/kg by decreasing pH from 9.5 and 5.0 when no carbonate was added. Increasing equilibrium carbonate concentrations between 8.6 10-2 and 76 10-2 mM decreased the KD about two-fold at pH 7.5. The KD values from meso-o,oEDDHA/Fe were up to 1000 fold larger than those of rac-o,oEDDHA/Fe at highest carbonate concentration at pH 7.5 and pH dependency suggests that former binds as inner sphere whereas latter binds as outer sphere. Despite the carbonate competition is unlikely to largely affect the net sorption of the chelate in soil, clear differences between meso-o,oEDDHA/Fe and rac-o,oEDDHA/Fe sorption rate on ferrihydrite in presence of carbonate were found.

Diffusion of Carbon Dioxide in Cordierite-like Structures: a FTIR Imaging Approach

NASA Astrophysics Data System (ADS)

Radica, F.; Bellatreccia, F.; Della Ventura, G.; Freda, C.; Cinque, G.; Cestelli Guidi, M.

2013-12-01

In the last decades microporous and mesoporous minerals have been recognized to be very important materials from both a geological and a technological viewpoint. In this context, cordierite plays a key role since it represents the only case of a widespread microporous mineral able to trap significant amounts of molecular H2O and CO2 [1] under extreme geological conditions, spanning from the amphibolite facies to ultra-high temperature metamorphism to crustal anatexis [2]. The analysis of volatiles in cordierite can be a very useful tool to define the composition of coexisting fluids during its formation, thus a deeper knowledge of their diffusion mechanism through the structure is crucial in petrologic studies. However, it may have significant implications on technological issues such as the design of new strategies for the permanent sequestration of atmospheric CO2. The incorporation of CO2 into cordierite has been studied by several authors [1, 3], who pointed out the extreme difficulty to reach the sample saturation and homogenization, implying that in experimental studies knowledge of the actual distribution of the volatile molecules in the run samples is crucial to derive any scientific conclusion. In this work, we addressed this problem using FTIR imaging. Our experiments were carried out in tandem on natural cordierite and synthetic CO2-free beryl, a mineral which is isostructural with cordierite. All samples were treated in CO2-saturated atmosphere at different pressure, temperature and time conditions using a non end-load piston-cylinder apparatus at INGV. The run products were oriented using a spindle stage, cut and doubly polished, and analyzed using polarized micro-FTIR spectroscopy at INFN-LNF in order to study the distribution across the sample and quantify the CO2 content. Preliminary data show that both pressure and time play a major role on the diffusion of gaseous CO2 in both cordierite and beryl, whereas the effect of temperature is less noticeable. High-resolution FPA (focal-plane-array of detectors) SR (synchrotron radiation)-FTIR imaging was done at beamline B22, Diamond laboratory (Oxford, UK). The data show that the diffusion of CO2 occurs exclusively along the structural channels running along the c-axis direction. Notably, the diffusion path of CO2 does not exceed 200 μm even after 10 days treatment. Sample cracks formed during the experimental runs speed up the gas diffusion; measured CO2 contents along these cracks are up to 4 times higher. Several CO2-rich samples were heat-treated up to 1200 °C using a Linkam heating stage to investigate the rate of CO2 evacuation as a function of temperature. In situ FTIR spectra have shown that the decarbonation process starts around 800 °C. Continuous heating experiments on 60 μm thick slabs pointed out that the diffusion rates are very low; complete CO2 extraction could not be achieved even after 2 hour heating at 1000 °C. [1] Armbruster and Bloss (1982) Am. Mineral. 67, 284-291. [2] Vry et al. (1990) Am. Mineral. 75, 71-88 [3] Le Breton (1989) Contrib. Mineral. Petrol. 103, 387-396.

Numerical simulation of structural evolution from regional to local scale in the Outokumpu ore district, eastern Finland

NASA Astrophysics Data System (ADS)

Zhang, Yanhua; Sorjonen-Ward, Peter; Ord, Alison; Kontinen, Asko

2015-04-01

Numerical simulations of geological processes may be used in several ways. On the one hand there is an analytical, or forensic approach, analogous to geophysical inversion, to constrain boundary conditions and to demonstrate how a particular geological process or sequence of events is feasible, or even probable. Alternatively, or additionally, modeling of earth processes can be used in a predictive sense, where forward modeling of various scenarios representing different initial states and applied boundary conditions and processes can provide generic or specific insights - depending on model complexity - which may be applied to problems as diverse as geohazard risk assessment and mineral exploration. These two approaches are complementary, and either may be emphasized, depending on the degree of understanding or density of data in a given study area. Here we review how the results of modeling can be used to develop and test structural scenarios and hypotheses and how they can be integrated with new data sets, in this case, deep crustal and upper crustal high resolution reflection seismic data acquired in recent years in the Paleoproterozoic Outokumpu ore district in eastern Finland. A range of process models have been devised and run for the Outokumpu mineral system, including coupled convective reactive transport models, coupled thermomechanical models assessing thermal regimes in rifting, and coupled mechanical and fluid flow models, but here we focus on the results of mechanical modeling using the finite element code FLAC. Models designed at different scales have provided simple and plausible solutions that affirm the geometric and kinematic scenarios based on regional and mine-scale structural data. At regional scale, FLAC models effectively simulated the partitioning of deformation into NW-SE trending ductile shear zones and domains where coeval folding and thrusting have NE-trending axial trends. At a more detailed district scale, development of local duplexing during folding of lithologically and mechanically diverse layered sequences - the serpentinites of the Outokumpu assemblage and the enclosing metaturbidites - was demonstrated in the FLAC simulations. The overall geometry is very reminiscent of dilational zones in ramp-flat imbricate fault systems that facilitate orogenic gold mineralization. At Outokumpu however, there is no evidence for hydrothermal transport of copper during regional metamorphism and deformation, yet the overall tabular form of the deposit demands significant structural mobilization. Hence, the system may be regarded as closed during peak metamorphic conditions, with essentially local remobilization and redistribution of components, possibly locally facilitated by decarbonation and dehydration reactions within altered metaperidotite lenses. Although we also simulated permeability structures and local fluid pathways in and around lenticular bodies - serpentinite proxies - that were both stronger and weaker than enclosing rock units, it must be admitted that there are few experimental or theoretically calculated constraints on rock behavior under such conditions. Thus, there are some earth environments and process that still elude our modeling capacity, with respect to thermodynamics and rheological behavior, in particular, the role of diffusion and mechanical behaviour of rocks dominated by quartz-sulfide mineralogy, subjected to amphibolites facies conditions for tens of millions of years.

Stable isotope geochemical study of Pamukkale travertines: New evidences of low-temperature non-equilibrium calcite-water fractionation

NASA Astrophysics Data System (ADS)

Kele, Sándor; Özkul, Mehmet; Fórizs, István; Gökgöz, Ali; Baykara, Mehmet Oruç; Alçiçek, Mehmet Cihat; Németh, Tibor

2011-06-01

In this paper we present the first detailed geochemical study of the world-famous actively forming Pamukkale and Karahayit travertines (Denizli Basin, SW-Turkey) and associated thermal waters. Sampling was performed along downstream sections through different depositional environments (vent, artificial channel and lake, terrace-pools and cascades of proximal slope, marshy environment of distal slope). δ 13C travertine values show significant increase (from + 6.1‰ to + 11.7‰ PDB) with increasing distance from the spring orifice, whereas the δ 18O travertine values show only slight increase downstream (from - 10.7‰ to - 9.1‰ PDB). Mainly the CO 2 outgassing caused the positive downstream shift (~ 6‰) in the δ 13C travertine values. The high δ 13C values of Pamukkale travertines located closest to the spring orifice (not affected by secondary processes) suggest the contribution of CO 2 liberated by thermometamorphic decarbonation besides magmatic sources. Based on the gradual downstream increase of the concentration of the conservative Na +, K +, Cl -, evaporation was estimated to be 2-5%, which coincides with the moderate effect of evaporation on the water isotope composition. Stable isotopic compositions of the Pamukkale thermal water springs show of meteoric origin, and indicate a Local Meteoric Water Line of Denizli Basin to be between the Global Meteoric Water Line (Craig, 1961) and Western Anatolian Meteoric Water Line (Şimşek, 2003). Detailed evaluation of several major and trace element contents measured in the water and in the precipitated travertine along the Pamukkale MM section revealed which elements are precipitated in the carbonate or concentrated in the detrital minerals. Former studies on the Hungarian Egerszalók travertine (Kele et al., 2008a, b, 2009) had shown that the isotopic equilibrium is rarely maintained under natural conditions during calcite precipitation in the temperature range between 41 and 67 °C. In this paper, besides the detailed geochemical analyses along downstream sections, we present new evidences of non-equilibrium calcite-water fractionation in lower temperature range (13.3 to 51.3 °C). Our measurements and calculations on natural hot water travertine precipitations at Pamukkale and Egerszalók revealed that the δ 18O travertine is equal with the δ 18O HCO3 at the orifice of the thermal springs, which means that practically there is no oxygen isotope fractionation between these two phases. High rate of CO 2 degassing with rapid precipitation of carbonate could be responsible for this as it was theoretically supposed by O'Neil et al. (1969). Thus, for the determination of the deposition temperature of a fossil travertine deposit we propose to use the water-bicarbonate oxygen isotope equilibrium fractionation instead of the water-travertine fractionation, which can result 8-9 °C difference in the calculated values. Our study is the first detailed empirical proof of O'Neil's hypothesis on a natural carbonate depositing system. The presented observations can be used to identify more precisely the deposition temperature of fossil travertines during paleoclimate studies.

Geochemical, isotopic and geochronological characterization of listvenite from the Upper Unit on Tinos, Cyclades, Greece

NASA Astrophysics Data System (ADS)

Hinsken, Tim; Bröcker, Michael; Strauss, Harald; Bulle, Florian

2017-06-01

We describe a largely unknown listvenite deposit from Tinos, Cyclades, Greece and combine field observations with petrographic, bulk-rock geochemical, isotope (Sr, O, C), and Rb-Sr geochronological data. The volumetrically small listvenite occurrences are associated with metabasic phyllites, talc schists, meta-gabbros, ophicalcites and serpentinites of the Upper Unit. Geochemical characteristics (high Mg#, Cr, Ni), as well as preserved relic Cr-spinel and the typical mesh-texture of serpentinized Mg-silicates, document derivation from ultramafic precursors. Judging from field and textural observations it is very likely that carbonation affected serpentinite and not unaltered meta-peridotite. The direct contact or transition zones to ultramafic rocks are not preserved, but serpentinites that escaped carbonation are closely associated. The listvenites occur near a low-angle normal fault that probably focused fluid infiltration and distribution. The carbonation is associated with the influx of CO2-rich, K-bearing fluids that led to the formation of ferroan magnesite, quartz and Cr-bearing white mica (fuchsite), but otherwise the transformation of serpentinized peridotite into listvenite had been a largely isochemical process. The studied rocks do not contain elevated concentrations of precious metals (Au, Pt, Pd). Field relationships suggest that the listvenite-bearing occurrences most likely represent the same tectonostratigraphic level as Upper Unit rocks that had been thermally overprinted in the contact aureole of Miocene granitoids at ca. 15 Ma. Accordingly the intrusion depth provides a minimum pressure constraint for the somewhat older carbonation. Pressure estimates for thermally overprinted rocks and the granitoids suggest an intrusion depth of ca. 7-10 km that corresponds to a pressure of ca. 2-3 kbar. Chlorite thermometry applied to the Tinos listvenites mostly indicates temperatures of ca. 250 °C during carbonation. Internal Rb-Sr mineral isochrons (different grain-size fractions of fuchsite and magnesite) yielded apparent ages of ca. 16 Ma and ca. 19 Ma, respectively, which are interpreted to date carbonation and associated fuchsite formation. The new ages indicate that listvenite formation is considerably younger than the presumed Late Cretaceous or Jurassic protolith age of the ultramafic precursors and also post-dates tectonic juxtaposition of the Upper Unit onto the Lower Unit at ca. 21 Ma. Although not the dominant process, a contribution of contact metamorphic decarbonation cannot completely be ruled out. The Sr isotope characteristics of magnesite and whole rocks correspond very well to the seawater curve for the formation age indicated by Rb-Sr dating. Carbonate carbon and oxygen isotopes measured for the listvenites suggest that magnesite formed following the deep circulation of fluids and their interaction with other carbonate rocks (possibly the marble units present on Tinos) including a possible contribution from magmatic CO2. The similarity in δ13C and δ18O between listvenite and some of the ophicalcite occurrences could indicate a common origin from the same circulating fluids, but remains elusive at present. Combined, P-T constraints and Sr isotope data imply infiltration of seawater-dominated fluids to a depth of several kilometers. This conclusion is supported by oxygen and carbon isotope data.

Sill intrusion driven fluid flow and vent formation in volcanic basins: Modeling rates of volatile release and paleoclimate effects

NASA Astrophysics Data System (ADS)

Iyer, Karthik; Schmid, Daniel

2016-04-01

Evidence of mass extinction events in conjunction with climate change occur throughout the geological record and may be accompanied by pronounced negative carbon isotope excursions. The processes that trigger such globally destructive changes are still under considerable debate. These include mechanisms such as poisoning from trace metals released during large volcanic eruptions (Vogt, 1972), CO2 released from lava degassing during the formation of Large Igneous Provinces (LIPs) (Courtillot and Renne, 2003) and CH4 release during the destabilization of sub-seafloor methane (Dickens et al., 1995), to name a few. Thermogenic methane derived from contact metamorphism associated with magma emplacement and cooling in sedimentary basins has been recently gaining considerable attention as a potential mechanism that may have triggered global climate events in the past (e.g. Svensen and Jamtveit, 2010). The discovery of hydrothermal vent complexes that are spatially associated with such basins also supports the discharge of greenhouse gases into the atmosphere (e.g. Jamtveit et al., 2004; Planke et al., 2005; Svensen et al., 2006). A previous study that investigated this process using a fluid flow model (Iyer et al., 2013) suggested that although hydrothermal plume formation resulting from sill emplacement may indeed release large quantities of methane at the surface, the rate at which this methane is released into the atmosphere is too slow to trigger, by itself, some of the negative δ13C excursions observed in the fossil record over short time scales observed in the fossil record. Here, we reinvestigate the rates of gas release during sill emplacement in a case study from the Harstad Basin off-shore Norway with a special emphasis on vent formation. The presented study is based on a seismic line that crosses multiple sill structures emplaced around 55 Ma within the Lower Cretaceous sediments. A single well-defined vent complex is interpreted above the termination of the main sill in the region. We use a 2D, hybrid FEM/FVM model that solves for fully compressible fluid flow to quantify the thermogenic release and transport of methane and to evaluate flow patterns within these systems. Additionally, vent formation in the model is implemented by simple fracture criteria that modify the permeability structure when the fluid pressure exceeds a threshold determined by the lithostatic pressure. The model with fracture formation is able to reproduce a single vent complex at the observed location above the main sill tip. This is very different from hydrothermal plume formation elsewhere in the region and occurs over short time scales (hundreds of years) and results in fluid focusing in that region. The rate of degassing and the resulting negative δ13C excursion from the vent model is then compared to models where only hydrothermal plume formation results in gas transportation. Lastly, variations in the amount of gas liberated in the system are investigated based on kerogen type and other mineral reactions such as limestone decarbonation and halite breakdown in the affected source rock.

Carbonate pseudotachylite? from a Miocene extensional detachment, W. Cyclades, Greece.

NASA Astrophysics Data System (ADS)

Rice, A. Hugh N.; Grasemann, Bernhard

2016-04-01

Most pseudotachylites, both impact- and fault-related, occur in silicate-rich rocks, typically with 'granitoid' compositions. Examples of melting in carbonate rocks, excluding magmatic sources, are restricted to impact-events, except for a carbonate pseudotachylite in the Canalone Fault, S. Italy (Viganò et al. 2011). Another potential example of carbonate pseudotachylite, shown here, comes from the Miocene-aged W. Cycladic Detachment System, in Greece. Top-SSE ductile to brittle movement on this detachment, with a maximum displacement estimated at tens of kilometers, exhumed of HP-rocks. The carbonate pseudotachylite occurs within an <200 mm thick zone of cataclasites developed between footwall carbonate ultramylonites, containing thin layers and cm-scale boudins of quartzite, and hanging wall breccias; no contacts with the footwall ultramylonites or hanging wall breccias has been found (yet). The cataclasite zone, which can be traced along-strike for at least 90 m, over ~20 m elevation, comprises several distinct layers. In the sample described, five layers occur. The lowest (A; >43 mm thick), consists of dark (hematitic) red, ultra-fine grained unlayered carbonate with up to 40x10 mm rather rounded clasts of earlier generations of cataclasite, many with a quartzite composition. These clasts are fractured and partially separated, with a fine red carbonate matrix. No layering of the matrix or clasts is apparent. The clasts become finer and more abundant towards the boundary with Layer B. Layers B and D (~57 & ~20 mm thick) dominantly comprises protocataclasite with greyish quartz fragments separated by a carbonate matrix along narrow fractures. Zone C and E (~23 m & >15 mm thick) comprise pale pink carbonate-dominated rocks with abundant <30x5 mm-sized red carbonate clasts (+/- quartz fragments) of earlier cataclasite generations. These elongate clasts lie parallel to the overall banding, which is parallel to the ultramylonitic foliation (detachment surface). Smaller clasts are markedly more rounded and comprise carbonate and quartzite material and may have darker (?reaction) rims. No layering is seen in the pale pink groundmass although this is present in some elongate clasts. All layer boundaries are irregular and no principle slip surfaces have been seen. Injection veins from 1 to 9 mm wide and up to at least 100 mm long derive from the central layer (C), cutting the overall layering at a high angle and branching in several places. These veins contain clasts comparable to those in Layer C. Both thick and thin injection-veins are rimmed by impersistent white calcite suggesting that injection was associated with precipitation of calcite. Whether Layer C (and perhaps E also) is a carbonate pseudotachylite is unknown. Although the injection veins are suggestive of this, these also occur in conjunction with ultracataclasites (Craddock et al. 2012). The irregular boundaries between the layers and the lack of any principal slip surfaces might indicate decarbonation and/or fluidization of gouge layer (Rowe and Griffith, 2015). Finally, abundant tubules, with rounded profiles and mostly sub-circular shapes up to 1.2 mm across, occur in Layers C and E, and less so D; these could be interpreted to reflect vents formed by partial carbonate degassing during melting.

Deployment, Design, and Commercialization of Carbon-Negative Energy Systems

NASA Astrophysics Data System (ADS)

Sanchez, Daniel Lucio

Climate change mitigation requires gigaton-scale carbon dioxide removal technologies, yet few examples exist beyond niche markets. This dissertation informs large-scale implementation of bioenergy with carbon capture and sequestration (BECCS), a carbon-negative energy technology. It builds on existing literature with a novel focus on deployment, design, commercialization, and communication of BECCS. BECCS, combined with aggressive renewable deployment and fossil emission reductions, can enable a carbon-negative power system in Western North America by 2050, with up to 145% emissions reduction from 1990 levels. BECCS complements other sources of renewable energy, and can be deployed in a manner consistent with regional policies and design considerations. The amount of biomass resource available limits the level of fossil CO2 emissions that can still satisfy carbon emissions caps. Offsets produced by BECCS are more valuable to the power system than the electricity it provides. Implied costs of carbon for BECCS are relatively low ( 75/ton CO2 at scale) for a capital-intensive technology. Optimal scales for BECCS are an order of magnitude larger than proposed scales found in existing literature. Deviations from optimal scaled size have little effect on overall systems costs - suggesting that other factors, including regulatory, political, or logistical considerations, may ultimately have a greater influence on plant size than the techno-economic factors considered. The flexibility of thermochemical conversion enables a viable transition pathway for firms, utilities and governments to achieve net-negative CO 2 emissions in production of electricity and fuels given increasingly stringent climate policy. Primary research, development (R&D), and deployment needs are in large-scale biomass logistics, gasification, gas cleaning, and geological CO2 storage. R&D programs, subsidies, and policy that recognize co-conversion processes can support this pathway to commercialization. Here, firms can embrace a gradual transition pathway to deep decarbonization, limiting economic dislocation and increasing transfer of knowledge between the fossil and renewable sectors. Global cumulative capital investment needs for BECCS through 2050 are over 1.9 trillion (2015$, 4% real interest rate) for scenarios likely to limit global warming to 2 °C. This scenario envisions deployment of as much as 24 GW/yr of BECCS by 2040 in the electricity sector. To achieve theses rates of deployment within 15-20 years, governments and firms must commit to research, development, and deployment on an unprecedented scale. Three primary issues complicate emissions accounting for BECCS: cross-sector CO2 accounting, regrowth, and timing. Switchgrass integration decreases lifecycle greenhouse gas impacts of co-conversion systems with CCS, across a wide range of land-use change scenarios. Risks at commercial scale include adverse effects on food security, land conservation, social equity, and biodiversity, as well as competition for water resources. This dissertation argues for an iterative risk management approach to BECCS sustainability, with standards being updated as more knowledge is gained through deployment. Sustainability impacts and public opposition to BECCS may be reduced with transparent measurement and communication. Commercial-scale deployment is dependent on the coordination of a wide range of actors, many with different incentives and worldviews. Despite this problem, this dissertation challenges governments, industry incumbents, and emerging players to research, support, and deploy BECCS.

Seismic velocities - density relationship for the Earth's crust: effects of chemical compositions, amount of water, and implications on gravity and topography

NASA Astrophysics Data System (ADS)

Guerri, Mattia; Cammarano, Fabio

2014-05-01

Seismic velocities - density relationship for the Earth's crust: effects of chemical compositions, amount of water, and implications on gravity and topography Mattia Guerri and Fabio Cammarano Department of Geosciences and Natural Resource Management, Section of Geology, University of Copenhagen, Denmark. A good knowledge of the Earth's crust is not only important to understand its formation and dynamics, but also essential to infer mantle seismic structure, dynamic topography and location of seismic events. Global and local crustal models available (Bassin et al., 2000; Nataf & Ricard, 1996; Molinari & Morelli, 2011) are based on VP-density empirical relationships that do not fully exploit our knowledge on mineral phases forming crustal rocks and their compositions. We assess the effects of various average crustal chemical compositions on the conversion from seismic velocities to density, also testing the influence of water. We consider mineralogies at thermodynamic equilibrium and reference mineral assemblages at given P-T conditions to account for metastability. Stable mineral phases at equilibrium have been computed with the revised Holland and Powell (2002) EOS and thermodynamic database implemented in PerpleX (Connolly 2005). We have computed models of physical properties for the crust following two approaches, i) calculation of seismic velocities and density by assuming the same layers structure of the model CRUST 2.0 (Bassin et al., 2000) and a 3-D thermal structure based on heat-flow measurements; ii) interpretation of the Vp model reported in CRUST 2.0 to obtain density and shear wave velocity for the crustal layers, using the Vp-density relations obtained with the thermodynamic modeling. The obtained density models and CRUST 2.0 one have been used to calculate isostatic topography and gravity field. Our main results consist in, i) phase transitions have a strong effect on the physical properties of crustal rocks, in particular on seismic velocities; ii) models based on different crustal chemical compositions show strong variations on both seismic properties and density; iii) the amount of water is a main factor in determining the physical properties of crustal rocks, drastically changing the phase stability in the mineralogical assemblages; iii) the differences between the various density models that we obtained, and the variations between them and CRUST2.0, translate into strong effects for the calculated isostatic topography and gravity field. Our approach, dealing directly with chemical compositions, is suitable to quantitatively investigate compositional heterogeneity in the Earth's crust. References - Bassin, C., Laske, G. & Masters, G., 2000. The current limits of resolution for surface wave tomography in North America, EOS, Trans. Am. Geophys. Un., 81, F897. - Nataf, H. & Ricard, Y., 1996. 3SMAC: an a priori tomographic model of the upper mantle based on geophysical modeling, Phys. Earth planet. Inter., 95(1-2), 101-122. - Molinari, I. & Morelli, A., 2011. Epcrust: a reference crustal model for the European Plate, Gepohys. J. Int., 185, 352-364. - Connolly JAD (2005) Computation of phase equilibria by linear programming: a tool for geodynamic modeling and its application to subduction zone decarbonation. Earth and Planetary Science Letters 236:524-541.

Integrated underground gas storage of CO2 and CH4 to decarbonize the "power-to-gas-to-gas-to-power" technology

NASA Astrophysics Data System (ADS)

Kühn, Michael; Streibel, Martin; Nakaten, Natalie; Kempka, Thomas

2014-05-01

Massive roll-out of renewable energy production units (wind turbines and solar panels) leads to date to excess energy which cannot be consumed at the time of production. So far, long-term storage is proposed via the so called 'power-to-gas' technology. Energy is transferred to methane gas and subsequently combusted for power production - 'power-to-gas-to-power' (PGP) - when needed. PGP profits from the existing infrastructure of the gas market and could be deployed immediately. However, major shortcoming is the production of carbon dioxide (CO2) from renewables and its emission into the atmosphere. We present an innovative idea which is a decarbonised extension of the PGP technology. The concept is based on a closed carbon cycle: (1) Hydrogen (H2) is generated from renewable energy by electrolysis and (2) transformed into methane (CH4) with CO2 taken from an underground geological storage. (3) CH4 produced is stored in a second storage underground until needed and (4) combusted in a combined-cycled power plant on site. (5) CO2 is separated during energy production and re-injected into the storage formation. We studied a show case for the cities Potsdam and Brandenburg/Havel in the Federal State of Brandenburg in Germany to determine the energy demand of the entire process chain and the costs of electricity (COE) using an integrated techno-economic modelling approach (Nakaten et al. 2014). Taking all of the individual process steps into account, the calculation shows an overall efficiency of 27.7 % (Streibel et al. 2013) with total COE of 20.43 euro-cents/kWh (Kühn et al. 2013). Although the level of efficiency is lower than for pump and compressed air storage, the resulting costs are similar in magnitude, and thus competitive on the energy storage market. The great advantage of the concept proposed here is that, in contrast to previous PGP approaches, this process is climate-neutral due to CO2 utilisation. For that purpose, process CO2 is temporally stored in an underground reservoir. If existing locations in Europe, where natural gas storage in porous formations is performed, were to be extended by CO2 storage sites, a significant quantity of wind and solar energy produced could be stored as methane. The overall process chain is in this case carbon neutral. Kühn M., Nakaten N., Streibel M., Kempka T. (2013) Klimaneutrale Flexibilisierung regenerativer Überschussenergie mit Untergrundspeichern. ERDÖL ERDGAS KOHLE 129(10), 348-352. Nakaten, N., Schlüter, R., Azzam, R., Kempka, T. (2014) Development of a techno-economic model for dynamic calculation of COE, energy demand and CO2 emissions of an integrated UCG-CCS process, Energy (in press). doi: 10.1016/j.energy.2014.01.014 Streibel M., Nakaten N., Kempka T., Kühn M. (2013) Analysis of an integrated carbon cycle for storage of renewables. Energy Procedia 40, 202-211. doi: 10.1016/j.egypro.2013.08.024.

Fluid and mass transfer at subduction interfaces-The field metamorphic record

NASA Astrophysics Data System (ADS)

Bebout, Gray E.; Penniston-Dorland, Sarah C.

2016-01-01

The interface between subducting oceanic slabs and the hanging wall is a structurally and lithologically complex region. Chemically disparate lithologies (sedimentary, mafic and ultramafic rocks) and mechanical mixtures thereof show heterogeneous deformation. These lithologies are tectonically juxtaposed at mm to km scales, particularly in more intensely sheared regions (mélange zones, which act as fluid channelways). This juxtaposition, commonly in the presence of a mobile fluid phase, offers up huge potential for mass transfer and related metasomatic alteration. Fluids in this setting appear capable of transporting mass over scales of kms, along flow paths with widely varying geometries and P-T trajectories. Current models of arc magmatism require km-scale migration of fluids from the interface into mantle wedge magma source regions and implicit in these models is the transport of any fluids generated in the subducting slab along and ultimately through the subduction interface. Field and geochemical studies of high- and ultrahigh-pressure metamorphic rocks elucidate the sources and compositions of fluids in subduction interfaces and the interplay between deformation and fluid and mass transfer in this region. Recent geophysical studies of the subduction interface - its thickness, mineralogy, density, and H2O content - indicate that its rheology greatly influences the ways in which the subducting plate is coupled with the hanging wall. Field investigation of the magnitude and styles of fluid-rock interaction in metamorphic rocks representing "seismogenic zone" depths (and greater) yields insight regarding the roles of fluids and elevated fluid pore pressure in the weakening of plate interface rocks and the deformation leading to seismic events. From a geochemical perspective, the plate interface contributes to shaping the "slab signature" observed in studies of the composition of arc volcanic rocks. Understanding the production of fluids with hybridized chemical/isotopic compositions could improve models aimed at identifying the relative contributions of end-member rock reservoirs through analyses of arc volcanic rocks. Production of rocks rich in hydrous minerals, along the subduction interface, could stabilize H2O to great depths in subduction zones and influence deep-Earth H2O cycling. Enhancement of decarbonation reactions and dissolution by fluid infiltration facilitated by deformation at the interface could influence the C flux from subducting slabs entering the sub-arc mantle wedge and various forearc reservoirs. In this paper, we consider records of fluid and mass transfer at localities representing various depths and structural expressions of evolving paleo-interfaces, ranging widely in structural character, the rock types involved (ultramafic, mafic, sedimentary), and the rheology of these rocks. We stress commonalities in styles of fluid and mass transfer as related to deformation style and the associated geometries of fluid mobility at subduction interfaces. Variations in thermal structure among individual margins will lead to significant differences in not only the rheology of subducting rocks, and thus seismicity, but also the profiles of devolatilization and melting, through the forearc and subarc, and the element/mineral solubilities in any aqueous fluids or silicate melts that are produced. One key factor in considering fluid and mass transfer in the subduction interface, influencing C cycling and other chemical additions to arcs, is the uncertain degree to which sub-crustal ultramafic rocks in downgoing slabs are hydrated and release H2O-rich fluids.

Earthquake induced variations in extrusion rate: A numerical modeling approach to the 2006 eruption of Merapi Volcano (Indonesia)

NASA Astrophysics Data System (ADS)

Carr, Brett B.; Clarke, Amanda B.; de'Michieli Vitturi, Mattia

2018-01-01

Extrusion rates during lava dome-building eruptions are variable and eruption sequences at these volcanoes generally have multiple phases. Merapi Volcano, Java, Indonesia, exemplifies this common style of activity. Merapi is one of Indonesia's most active volcanoes and during the 20th and early 21st centuries effusive activity has been characterized by long periods of very slow (<0.1 m3 s-1) extrusion rate interrupted every few years by short episodes of elevated extrusion rates (1-4 m3 s-1) lasting weeks to months. One such event occurred in May-July 2006, and previous research has identified multiple phases with different extrusion rates and styles of activity. Using input values established in the literature, we apply a 1D, isothermal, steady-state numerical model of magma ascent in a volcanic conduit to explain the variations and gain insight into corresponding conduit processes. The peak phase of the 2006 eruption occurred in the two weeks following the May 27 Mw 6.4 earthquake 50 km to the south. Previous work has suggested that the peak extrusion rates observed in early June were triggered by the earthquake through either dynamic stress-induced overpressure or the addition of CO2 due to decarbonation and gas escape from new fractures in the bedrock. We use the numerical model to test the feasibility of these proposed hypotheses and show that, in order to explain the observed change in extrusion rate, an increase of approximately 5-7 MPa in magma storage zone overpressure is required. We also find that the addition of ∼1000 ppm CO2 to some portion of the magma in the storage zone following the earthquake reduces water solubility such that gas exsolution is sufficient to generate the required overpressure. Thus, the proposed mechanism of CO2 addition is a viable explanation for the peak phase of the Merapi 2006 eruption. A time-series of extrusion rate shows a sudden increase three days following the earthquake. We explain this three-day delay by the combined time required for the effects of the earthquake and corresponding CO2 increase to develop in the magma storage system (1-2 days), and the time we calculate for the affected magma to ascend from storage zone to surface (40 h). The increased extrusion rate was sustained for 2-7 days before dissipating and returning to pre-earthquake levels. During this phase, we estimate that 3.5 million m3 DRE of magma was erupted along with 11 ktons of CO2. The final phase of the 2006 eruption was characterized by highly variable extrusion rates. We demonstrate that those changes were likely controlled by failure of the edifice that had been confining the dome to Merapi's crater and subsequent large dome collapses. The corresponding reductions in confining pressure caused increased extrusion rates that rapidly rebuilt the dome and led to further collapses, a feedback cycle that prolonged the eruption. In a more general sense, this study demonstrates that both internal changes, such as magma volatile content and overpressure, and external forces, such as edifice collapse and regional earthquakes, can affect variations in eruption intensity. Further, we also demonstrate how these external forces can initiate internal changes and how these parameters may interact with one another in a feedback scenario.

Renewable Energy Zones for Balancing Siting Trade-offs in India

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

Deshmukh, Ranjit; Wu, Grace C.; Phadke, Amol

India’s targets of 175 GW of renewable energy capacity by 2022, and 40% generation capacity from non-fossil fuel sources by 2030 will require a rapid and dramatic increase in solar and wind capacity deployment and overcoming its associated economic, siting, and power system challenges. The objective of this study was to spatially identify the amount and quality of wind and utility-scale solar resource potential in India, and the possible siting-related constraints and opportunities for development of renewable resources. Using the Multi-criteria Analysis for Planning Renewable Energy (MapRE) methodological framework, we estimated several criteria valuable for the selection of sites formore » development for each identified potential "zone", such as the levelized cost of electricity, distance to nearest substation, capacity value (or the temporal matching of renewable energy generation to demand), and the type of land cover. We find that high quality resources are spatially heterogeneous across India, with most wind and solar resources concentrated in the southern and western states, and the northern state of Rajasthan. Assuming India's Central Electricity Regulatory Commission's norms, we find that the range of levelized costs of generation of wind and solar PV resources overlap, but concentrated solar power (CSP) resources can be approximately twice as expensive. Further, the levelized costs of generation vary much more across wind zones than those across solar zones because of greater heterogeneity in the quality of wind resources compared to that of solar resources. When considering transmission accessibility, we find that about half of all wind zones (47%) and two-thirds of all solar PV zones (66%) are more than 25 km from existing 220 kV and above substations, suggesting potential constraints in access to high voltage transmission infrastructure and opportunities for preemptive transmission planning to scale up RE development. Additionally and importantly, we find that about 84% of all wind zones are on agricultural land, which provide opportunities for multiple-uses of land but may also impose constraints on land availability. We find that only 29% of suitable solar PV sites and 15% of CSP sites are within 10 km of a surface water body suggesting water availability as a significant siting constraint for solar plants. Availability of groundwater resources was not analyzed as part of this study. Lastly, given the possible economic benefits of transmission extensions or upgrades that serve both wind and solar generators, we quantified the co-location opportunities between the two technologies and find that about a quarter (28%) of all solar PV zones overlap with wind zones. Using the planning tools made available as part of this study, these multiple siting constraints and opportunities can be systematically compared and weighted to prioritize development that achieves a particular technology target. Our results are limited by the uncertainties associated with the input datasets, in particular the geospatial wind and solar resource, transmission, and land use land cover datasets. As input datasets get updated and improved, the methodology and tools developed through this study can be easily adapted and applied to these new datasets to improve upon the results presented in this study. India is on a path to significantly decarbonize its electricity grid through wind and solar development. A stakeholder-driven, systematic, and integrated planning approach using data and tools such as those highlighted in this study is essential to not only meet the country's RE targets, but to meet them in a cost-effective, and socially and environmentally sustainable way.« less

The Price-Concentration Relationship in Early Residential Solar Third-Party Markets

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

Pless, Jacquelyn; Langheim, Ria; Machak, Christina

The market for residential solar photovoltaic (PV) systems in the United States has experienced tremendous growth over the past decade, with installed capacity more than doubling between 2014 and 2016 alone (SEIA, 2016). As the residential market continues to grow, it prompts new questions about the nature of competition between solar installers and how this competition, or lack thereof, affects the prices consumers are paying. It is often assumed that more competition leads to lower prices, but this is not universally true. For example, some studies have shown that factors such as brand loyalty could lead to a negative relationshipmore » between concentration and price in imperfectly competitive markets (Borenstein, 1985; Holmes, 1989). As such, the relationship between prices and market concentration is an open empirical question since theory could predict either a positive or negative relationship. Determining a relationship between prices and market concentration is challenging for several reasons. Most significantly, prices and market structure are simultaneously determined by each other -- the amount of competition a seller faces influences the price they can command, and prices determine a seller's market share. Previous studies have examined recent PV pricing trends over time and between markets (Davidson et al., 2015a; Davidson and Margolis 2015b; Nemet et al., 2016; Gillingham et al., 2014; Barbose and Darghouth 2015). While these studies of solar PV pricing are able to determine correlations between prices and market factors, they have not satisfactorily proven causation. Thus, to the best of our knowledge, there is little work to date that focuses on identifying the causal relationship between market structure and the prices paid by consumers. We use a unique dataset on third-party owned contract terms for the residential solar PV market in the San Diego Gas and Electricity service territory to better understand this relationship. Surprisingly, we find that firms charged higher prices in more competitive markets in our sample. The finding is robust across multiple definitions of firm concentration. There are at least two potential explanations for our findings. First, firms could be conducting entry deterrence strategies. It is possible that firms are acting in a non-competitive way and setting prices lower than they would be otherwise. Setting low prices that are below potential competitors' marginal costs could deter entrants and ensure a larger market share. Second, there could be a group of dominant firms (with a competitive fringe), and the dominant firms may occasionally engage in price wars. If this is true, prices should be lower in more concentrated markets during the price wars (Salinger, 1990). As the rooftop PV market continues to grow, market structure will remain a relevant policy issue in consideration of the potential for rooftop solar to contribute to de-carbonization efforts or other policy objectives. This paper adds to a growing emphasis on understanding supply-side factors in scaling up solar markets in the residential sector. Generally, solar markets have become more competitive over the same time period that solar technology costs decreased. While solar system hard costs have come down, our research suggests that total costs are more nuanced in early solar system TPO markets. Policymakers should consider these findings when designing markets, and have the data needed to make informed decisions.« less

Changes in Sediment Provenance to the Southeast Newfoundland Ridge from the late Eocene to the Early Oligocene; Northern Hemisphere Glaciation or Deep Water Circulation?

NASA Astrophysics Data System (ADS)

Scher, H. D.; Romans, B.; Moffett, Z. J.; Buckley, W. P.; Gibson, K.

2013-12-01

We report radiogenic isotope results from IODP Site U1411 (41° 37.10' N; 48° 59.98' W; 3300 m) on the Southeast Newfoundland Ridge (SENR) that span the Eocene Oligocene Transition (EOT). Neodymium (Nd) and strontium (Sr) isotope compositions of decarbonated and acid-reduced bulk sediments (i.e., the terrigenous fraction) are consistent with sources from ancient cratons on the Canadian, Greenland, and Fennoscandian shields. Down-core Nd isotope records were generated from the terrigenous fraction and fossil fish teeth at a resolution of 50 kyr spanning the late Eocene to the early Oligocene (ca. 37.5 to 32 Ma). The Nd isotope record of the terrigenous fraction reveals variability on two time scales. First, a long-term shift to less radiogenic ɛNd values occurs from the late Eocene to the early Oligocene. In the late Eocene the baseline ɛNd value is -14 and decreases to -18 in the early Oligocene. The main phase of the long-term shift begins after 34.6 Ma. Second, there are two short-lived excursions toward less radiogenic ɛNd values during the Eocene. Both excursions are on the order of 200 - 300 kyr and involve a shift from the late Eocene baseline ɛNd value of -14 to -18. The older excursion is from 37.3 to 37.0 Ma and the younger excursion from 36.2 to 36.0 Ma. The fossil fish tooth Nd isotope record indicates that the source of Nd to bottom waters at U1411 did not change over the investigated interval. Fossil fish tooth ɛNd values average -10.3 × 0.8 ɛNd (2σ, n=75). This level of ɛNd variability is very low compared to other Nd isotope records spanning the EOT. Both the long and short-term terrigenous ɛNd variability indicates changes in sediment provenance to the study site. A change in sediment provenance can be attributed to either 1) a change in the strength or position of the Deep Western Boundary Current that supplies sediment to the site or 2) an influx of sediment to the North Atlantic resulting from enhanced weathering/erosion on adjacent continents. There is not a long term trend nor prominent inflections in the fossil fish tooth ɛNd record that are associated with terrigenous ɛNd values so it does not appear likely that changes in sediment provenance were accompanied by a reorganization of deep water masses. Thus the preliminary results are cautiously interpreted as reflecting a sedimentological response to an overall increase in weathering/erosion of ancient continental crust, possibly on Greenland, over the investigated interval. In this context these results may reflect the emplacement of northern hemisphere ice sheets in the latest Eocene, preceded by prominent short-lived glacial events in the Eocene. The first short-lived event falls within polarity chron C17n.1n, which corresponds with the timing of a known Eocene glaciation on Antarctica and suggests that the greenhouse climate in the late Eocene supported a bipolar glacial event. We are currently generating a record of relative paleo-bottom current intensity from U1411 using the sortable silt proxy to further evaluate the role of bottom currents in terrigenous sediment provenance on the SENR.

C-O-H-N fluids circulations and graphite precipitation in reactivated Hudsonian shear zones during basement uplift of the Wollaston-Mudjatik Transition Zone: Example of the Cigar Lake U deposit

NASA Astrophysics Data System (ADS)

Martz, Pierre; Cathelineau, Michel; Mercadier, Julien; Boiron, Marie-Christine; Jaguin, Justine; Tarantola, Alexandre; Demacon, Mickael; Gerbeaud, Olivier; Quirt, David; Doney, Amber; Ledru, Patrick

2017-12-01

Graphitic shear zones are spatially associated with unconformity-related uranium deposits that are located around the unconformity between the strata of the Paleo- to Mesoproterozoic Athabasca Basin (Saskatchewan, Canada) and its underlying Archean to Paleoproterozoic basement. The present study focuses on basement-hosted ductile-brittle graphitic shear zones near the Cigar Lake U deposit, one of the largest unconformity-related U deposits. The goal of the study is to decipher the pre-Athabasca Basin fluid migration history recorded within such structures and its potential role on the formation of such exceptional deposit. Dominantly C-O-H(-N) metamorphic fluids have been trapped in Fluid Inclusion Planes (FIPs) in magmatic quartz within ductile-brittle graphitic shear zones active during retrograde metamorphism associated with the formation of the Wollaston-Mudjatik Transition Zone (WMTZ) between ca. 1805 and 1720 Ma. Such fluids show a compositional evolution along the retrograde path, from a dense and pure CO2 fluid during the earliest stages, through a lower density CO2 ± CH4-N2 (± H2O) fluid and, finally, to a very low density CH4-N2 fluid. Statistical study of the orientation, distribution, proportion, and chemical characterization of the FIPs shows that: i) CO2 (δ13CCO2 around - 9‰ PDB) from decarbonation reactions and/or partial water-metamorphic graphite equilibrium initially migrated regionally and pervasively under lithostatic conditions at about 500 to 800 °C and 150 to 300 MPa. Such P-T conditions attest to a high geothermal gradient of around 60 to 90 °C/km, probably related to rapid exhumation of the basement or a large-scale heat source. ii) Later brittle reactivation of the shear zone at around 450 °C and 25-50 MPa favored circulation of CO2-CH4-N2(± H2O) fluids in equilibrium with metamorphic graphite (δ13CCO2 around - 14‰) under hydrostatic conditions and only within the shear zones. Cooling of these fluids and the water uptake linked to fluid-basement rock reactions led to the precipitation at around 450 °C of poorly-crystallized hydrothermal graphite. This graphite presents isotopic (δ13C - 30 to - 26‰ PDB) and morphological differences from the high-T metamorphic graphite (> 600 °C, - 29 to - 20‰ δ13C) derived from metamorphism of C-rich sedimentary material. The brittle structural reactivation and the related fluid migration and graphite precipitation were specifically focused within the shear zones and related damage zones. The brittle reactivation produced major changes in the petro-physical, mineralogical, and chemical characteristics of the structures and their damage zones. It especially increased the fracture paleoporosity and rock weakness toward the fault cores. These major late metamorphic modifications of the graphitic shear zones were likely key parameters favoring the enhanced reactivity of these basement zones under tectonic stress following deposition of the Athabasca Basin, and so controlled basinal brine movement at the basin/basement interface related to the formation of the unconformity-related uranium deposits. This relationship consequently readily explains the specific spatial relationships between unconformity-related U deposits and the ductile-brittle graphitic shear zones.

The reform of energy subsidies for the enhancement of marine sustainability: An empirical analysis of energy subsidies worldwide and an in-depth case study of South Korea's energy subsidy policies

NASA Astrophysics Data System (ADS)

Shim, Jae Hyun

This dissertation seeks to raise awareness about harmful effects of fossil fuel and nuclear energy subsidies that have blocked transition from conventional energy to a decarbonized, renewable energy system. Today, humans face daunting challenges in the form of global warming, which results mainly from the burning of fossil fuels. To avoid catastrophe, the transition to a renewable energy regime should be an urgent priority; however, the reality is that the progress of renewable energy is very slow due to the various political and economic factors when compared to conventional energy resources. A chief factor is that the energy subsidy for fossil fuel and nuclear energy obstructs the "level playing field" for renewable energy. Energy subsidies for conventional energy can be understood in the context of the commodification paradigm, which regards nature as an object of conquest and supports the principle of more is better. Although fossil fuel energy damages the environment, economy, and social equity, all countries subsidize such energy, no matter the country's state of development. This holds true as much in the U.S. and the EU as in China, India and South Korea. The oceans, which cover 71% of the earth, are threatened by the activities of conventional energy, which are underpinned by subsidies. These subsidies have contributed to the destruction of the marine ecosystem through increased GHG emissions like CO2 and NOx which cause a sea temperature increase and coral bleaching. Subsidies also significantly affect fishery overexploitation, oil pollution, and thermal pollution. In-depth empirical analysis of South Korea showed how fossil fuel and nuclear energy activities have threatened marine sustainability through thermal pollution, algae bloom (red tides), overexploitation, and oil-related marine pollution. Reforming subsidies of fossil fuel and nuclear energy should be a global priority because of imminent of global warming. As strategies for energy subsidy reforms, first of all, humans need a new energy paradigm to replace the hitherto dominant commodification paradigm. On an international level, creation of an international renewable energy agency and creation of renewable funds will spur on energy subsidy reforms of all nations, especially developing countries. On a national level, government's role should change from growth-oriented economic policy to sustainable development that includes environmentally friendly energy systems. In terms of social welfare, energy subsidies should be transformed to direct income policy, which is more effective for the welfare of the poor. The South Korean government should exchange its current supply-oriented fishery policy, which relies heavily on energy subsidies, to a Marine Reserves policy and direct income policy. For successful energy subsidy reforms, the government, NGOs, and private market should cooperate. Specifically, NGOs' role in monitoring and pushing government's energy subsidy reform is invaluable, considering the limits of modern bureaucracy and the profit-oriented market character. Most environmental problems, including global warming, have a close relation with fossil fuel and nuclear energy use. Historically, these energy systems have become entrenched deeply in society through energy subsidy policy. Energy subsidy reforms are a key to the environmental problem and accelerated transition to renewable energy.

Corrosion inhibition by inorganic cationic inhibitors on the high strength alumunium alloy, 2024-T3

NASA Astrophysics Data System (ADS)

Chilukuri, Anusha

The toxicity and carcinogenic nature of chromates has led to the investigation of environmentally friendly compounds that offer good corrosion resistance to AA 2024-T3. Among the candidate inhibitors are rare earth metal cationic (REM) and zinc compounds, which have received much of attention over the past two decades. A comparative study on the corrosion inhibition caused by rare earth metal cations, Ce3+, Pr3+, La3+ and Zn2+ cations on the alloy was done. Cathodic polarization showed that these inhibitor ions suppress the oxygen reduction reaction (ORR) to varying extents with Zn2+ providing the best inhibition. Pr3+ exhibited windows of concentration (100-300 ppm) in which the corrosion rate is minimum; similar to the Ce3+ cation. Scanning Electron Microscopy (SEM) studies showed that the mechanism of inhibition of the Pr3+ ion is also similar to that of the Ce3+ ion. Potentiodynamic polarization experiments after 30 min immersion time showed greatest suppression of oxygen reduction reaction in neutral chloride solutions (pH 7), which reached a maximum at a Zn2+ ion concentration of 5 mM. Anodic polarization experiments after 30 min immersion time, showed no anodic inhibition by the inhibitor in any concentration (0.1 mM - 10 mM) and at any pH. However, anodic polarization of samples immersed after longer immersion times (upto 4 days) in mildly acidic Zn2+ (pH 4) solutions showed significant reduction in anodic kinetics indicating that zinc also acts as a “slow anodic inhibitor”. In contrast to the polarization experiments, coupons exposed to inhibited acidic solutions at pH 4 showed complete suppression of dissolution of Al2CuMg particles compared to zinc-free solutions in the SEM studies. Samples exposed in pH 4 Zn2+-bearing solution exhibited highest polarization resistance which was also observed to increase with time. In deaerated solutions, the inhibition by Zn2+ at pH 4 is not observed as strongly. The ability to make the interfacial electrolyte alkaline is retarded in the absence of oxygen. As a result precipitation of Zn oxides and hydroxides was suppressed. Impedance in decarbonated chloride solutions showed that the absence of CO 2 reduces inhibition by Zn2+ at pH 4. The carbonate protective layer formed in aerated solutions is essential for providing better protection of the substrate at pH 4. Inhibitor cations were exchanged into insoluble ion-exchanging sodium bentonites and incorporated as pigments in organic coatings applied to AA 2024-T3 substrates. XRD of the pigments ensured ion exchange and UV-visible spectroscopy was used to characterize inhibitor ion release from the bentonites. Salt spray exposure tests on scribed panels were preformed and results were compared to those from SrCrO4 pigmented coatings. Zn-exchanged bentonite pigmented coatings showed better performance compared to the other exchanged bentonites when incorporated into epoxy coatings with total impedance magnitude in the same order as SrCrO4. PVB (Polyvinyl Butyral) coatings containing Zn bentonite, however, did not show superior behaviour in the impedance response due to less or no water uptake. Salt spray exposures for a period of 336 h, showed that Zn bentonite incorporated into PVB suppressed blistering compared to the neat PVB and other pigmented bentonites.

Metamorphic Perspectives of Subduction Zone Volatiles Cycling

NASA Astrophysics Data System (ADS)

Bebout, G. E.

2008-12-01

Field study of HP/UHP metamorphic rocks provides "ground-truthing" for experimental and theoretical petrologic studies estimating extents of deep volatiles subduction, and provides information regarding devolatilization and deep subduction-zone fluid flow that can be used to reconcile estimates of subduction inputs and arc volcanic outputs for volatiles such as H2O, N, and C. Considerable attention has been paid to H2O subduction in various bulk compositions, and, based on calculated phase assemblages, it is thought that a large fraction of the initially structurally bound H2O is subducted to, and beyond, subarc regions in most modern subduction zones (Hacker, 2008, G-cubed). Field studies of HP/UHP mafic and sedimentary rocks demonstrate the impressive retention of volatiles (and fluid-mobile elements) to depths approaching those beneath arcs. At the slab-mantle interface, high-variance lithologies containing hydrous phases such as mica, amphibole, talc, and chlorite could further stabilize H2O to great depth. Trench hydration in sub-crustal parts of oceanic lithosphere could profoundly increase subduction inputs of particularly H2O, and massive flux of H2O-rich fluids from these regions into the slab-mantle interface could lead to extensive metasomatism. Consideration of sedimentary N concentrations and δ15N at ODP Site 1039 (Li and Bebout, 2005, JGR), together with estimates of the N concentration of subducting altered oceanic crust (AOC), indicates that ~42% of the N subducting beneath Nicaragua is returned in the corresponding volcanic arc (Elkins et al., 2006, GCA). Study of N in HP/UHP sedimentary and basaltic rocks indicates that much of the N initially subducted in these lithologies would be retained to depths approaching 100 km and thus available for addition to arcs. The more altered upper part of subducting oceanic crust most likely to contribute to arcs has sediment-like δ15NAir (0 to +10 per mil; Li et al., 2007, GCA), and study of HP/UHP eclogites indicates retention of seafloor N signatures and, in some cases, enrichments in sedimentary N due to forearc metamorphic fluid-rock interactions (Halama et al., this session). A global estimate of C cycling, using seafloor inputs (carbonate and organic matter) and estimates of volcanic CO2 outputs, indicates ~40% return (with large uncertainty) of the subducting C in volcanic gases. This imbalance appears plausible, given the evidence for deep carbonate subduction, in UHP marbles, and the preservation of graphite in UHP metasediments, together seemingly indicating that large fractions of subducting C survive forearc-to-subarc metamorphism. Estimates of return efficiency in the Central America arc, based on data for volcanic gases, are lower and variable along strike (12-29%), quite reasonably explained by de Leeuw et al. (2007, EPSL) as resulting from incomplete decarbonation of subducting sediment and AOC, fluid flow patterns expected given sediment section thickness, and varying degrees of forearc underplating. The attempts to mass-balance C and N across individual arc-trench systems demonstrate valuable integration of information from geophysical, field, petrologic, and geochemical observations. Studies of subduction-zone metamorphic suites can yield constraints on the evolution of deeply subducting rocks and the physicochemical characteristics of fluids released in forearcs and contributing to return flux in arc volcanic gases.

Considering the Role of Natural Gas in the Deep Decarbonization of the U.S. Electricity Sector. Natural Gas and the Evolving U.S. Power Sector Monograph Series: Number 2

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

Cole, Wesley; Beppler, Ross; Zinaman, Owen

Natural gas generation in the U.S. electricity sector has grown substantially in recent years, while the sector's carbon dioxide (CO2) emissions have generally declined. This relationship highlights the concept of natural gas as a potential enabler of a transition to a lower-carbon future. This work considers that concept by using the National Renewable Energy Laboratory (NREL) Renewable Energy Deployment System (ReEDS) model. ReEDS is a long-term capacity expansion model of the U.S. electricity sector. We examine the role of natural gas within the ReEDS modeling framework as increasingly strict carbon emission targets are imposed on the electricity sector. In additionmore » to various natural gas price futures, we also consider scenarios that emphasize a low-carbon technology in order to better understand the role of natural gas if that low-carbon technology shows particular promise. Specifically, we consider scenarios with high amounts of energy efficiency (EE), low nuclear power costs, low renewable energy (RE) costs, and low carbon capture and storage (CCS) costs. Within these scenarios we find that requiring the electricity sector to lower CO2 emissions over time increases near-to-mid-term (through 2030) natural gas generation (see Figure 1 - left). The long-term (2050) role of natural gas generation in the electricity sector is dependent on the level of CO2 emission reduction required. Moderate reductions in long-term CO2 emissions have relatively little impact on long-term natural gas generation, while more stringent CO2 emission limits lower long-term natural gas generation (see Figure 1 - right). More stringent carbon targets also impact other generating technologies, with the scenarios considered here seeing significant decreases in coal generation, and new capacity of nuclear and renewable energy technologies over time. Figure 1 also demonstrates the role of natural gas in the context of scenarios where a specific low-carbon technology is advantaged. In 2030, natural gas generation in the technology scenarios is quite similar to that in the reference scenarios, indicating relatively little change in the role of natural gas in the near-to-mid-term due to advancements in those technology areas. The 2050 natural gas generation shows more significant differences, suggesting that technology advancements will likely have substantial impacts on the role of natural gas in the longer-term timeframe. Natural gas generation differences are most strongly driven by alternative natural gas price trajectories--changes in natural gas generation in the Low NG Price and High NG Price scenarios are much larger than in any other scenario in both the 2030 and 2050 timeframes. The only low-carbon technology scenarios that showed any increase in long-term natural gas generation relative to the reference case were the Low CCS cost scenarios. Carbon capture and storage technology costs are currently high, but have the potential to allow fossil fuels to play a larger role in low-carbon grid. This work considers three CCS cost trajectories for natural gas and coal generators: a baseline trajectory and two lower cost trajectories where CO2 capture costs reach $40/metric ton and $10/metric ton, respectively. We find that in the context of the ReEDS model and with these assumed cost trajectories, CCS can increase the long-term natural gas generation under a low carbon target (see Figure 2). Under less stringent carbon targets we do not see ReEDS electing to use CCS as part of its electricity generating portfolio for the scenarios considered in this work.« less

The loess-paleosol profile Datthausen, on the penultimate-glacial terrace of the upper Danube River: Sedimentological and paleopedological characteristics

NASA Astrophysics Data System (ADS)

Sauer, Daniela; Kadereit, Annette; Kühn, Peter; Herrmann, Ludger; Kösel, Michael; Miller, Christopher; Shinonaga, Taeko; Kreutzer, Sebastian; Starkovich, Britt

2015-04-01

Here we present a new loess profile, exposed in the gravel quarry Datthausen on the penultimate-glacial terrace of the upper Danube River, 40 km SW of Ulm, Germany. The loess in this region is by far not as thick and differentiated as in the Upper and Middle Rhine regions or in the Basin of Mainz; nevertheless, we found several similarities between those and the profile Datthausen. The profile is located in the East wall of the quarry, in a flat channel filled by reworked loess. It was sampled for grain size analysis, chemical standard analyses, analysis of the clay mineral assemblage (XRD of oriented clay specimen) and soil thin section analysis. Five luminescence dates provide a time frame (see Kadereit et al. in this session for further details). The profile starts above the Eemian paleosol, which is developed in penultimate-glacial gravel of the Danube River. No early Würmian soils are preserved; the basal section of the profile comprises a succession of several middle Würmian (MIS3) brown soil horizons (9BCr to 6Bg5; Table 1). Two additional brown horizons (5Bg4 and 5Bg3) follow on top. They both have a slight olive tint, and the upper one shows clear features of redox processes and reworking. A thin gravel band on top of the olive-brown soil horizons can be traced over ca. 170 m along the wall (4Bg2). Above the gravel band two brown, only slightly de-carbonated soil horizons (3Bw1 and 2Bg1) and two hydromorphic horizons (Cg2 and Cg1) follow. The top of the profile is made up of a Luvisol comprising the horizon sequence Ap-Bt-BCtg1-BCtg2. Table 1: Main soil-morphological characteristics of the loess-paleosol profile Datthausen Depth; horizon (FAO); color (dry, moist); structure; major characteristics -30 cm: Ap -70 cm: Bt; 10YR5/6, 10YR4/6; angular blocky and prismatic; earthworm feces, channels, clay coatings -100 cm: BCtg1; 10YR7/4, 10YR5/4; massive, pinholes; mottled, fine Mn nodules, clay coatings in channels -125 cm: BCtg2; 10YR6/4, 10YR4/4; massive, pinholes; mottled, fine Mn nodules, clay coatings in channels -150 cm: Cg1; 2.5Y7/4, 2.5Y5/; massive (fine sandy layers); fine rusty spots and Mn nodules -190 cm: Cg2; 2.5Y7/3, 2.5Y5/4; massive (fine sandy layers); mottled, fine rusty spots (2 mm) -220 cm: 2Bg1; 10YR6/4, 10YR4/4; massive to fine platy, pinholes; intense brown, slightly mottled -260 cm: 3Bw1; 10YR6/4, 10YR5/4; massive to fine platy, pinholes; snail shell fragments -275 cm: 4Bg2; 10YR6/4, 10YR5/4; massive to fine platy, pinholes; slightly mottled -300 cm: 5Bg3; 10YR6/4, 10YR5/4; massive to fine platy, pinholes; very fine Fe+Mn mottles, slight olive tint -312 cm: 5Bg4; 10YR6/4, 10YR4/4; massive to fine platy; slight olive tint, fine Fe mottles and Mn nodules -355 cm: 6Bg5; 10YR6/4, 10YR4/6; massive to fine platy; more reddish than 5Bg4, fine Mn nodules -400 cm: 7Bg6; 10YR6/4, 10YR4/4; weakly fine platy and sub. blocky, pinholes; Mn mottles and coatings -435 cm: 8Bw2; 10YR6/4, 10YR4/4; weakly subangular blocky, pinholes -465 cm: 9BCr; 2.5Y7/4, 2.5Y5/4; weakly subangular blocky; grayish, bleached and rusty mottles

Rethinking wedges

NASA Astrophysics Data System (ADS)

Davis, Steven J.; Cao, Long; Caldeira, Ken; Hoffert, Martin I.

2013-03-01

Abstract Stabilizing CO2 emissions at current levels for fifty years is not consistent with either an atmospheric CO2 concentration below 500 ppm or global temperature increases below 2 °C. Accepting these targets, solving the climate problem requires that emissions peak and decline in the next few decades, and ultimately fall to near zero. Phasing out emissions over 50 years could be achieved by deploying on the order of 19 'wedges', each of which ramps up linearly over a period of 50 years to ultimately avoid 1 GtC y-1 of CO2 emissions. But this level of mitigation will require affordable carbon-free energy systems to be deployed at the scale of tens of terawatts. Any hope for such fundamental and disruptive transformation of the global energy system depends upon coordinated efforts to innovate, plan, and deploy new transportation and energy systems that can provide affordable energy at this scale without emitting CO2 to the atmosphere. 1. Introduction In 2004, Pacala and Socolow published a study in Science arguing that '[h]umanity can solve the carbon and climate problem in the first half of this century simply by scaling up what we already know how to do' [1]. Specifically, they presented 15 options for 'stabilization wedges' that would grow linearly from zero to 1 Gt of carbon emissions avoided per year (GtC y-1 1 Gt = 1012 kg) over 50 years. The solution to the carbon and climate problem, they asserted, was 'to deploy the technologies and/or lifestyle changes necessary to fill all seven wedges of the stabilization triangle'. They claimed this would offset the growth of emissions and put us on a trajectory to stabilize atmospheric CO2 concentration at 500 ppm if emissions decreased sharply in the second half of the 21st century. The wedge concept has proven popular as an analytical tool for considering the potential of different technologies to reduce CO2 emissions. In the years since the paper was published, it has been cited more than 400 times, and stabilization wedges have become a ubiquitous unit in assessing different strategies to mitigate climate change (e.g. [2-5]). But the real and lasting potency of the wedge concept was in dividing the daunting problem of climate change into substantial but tractable portions of mitigation: Pacala and Socolow gave us a way to believe that the energy-carbon-climate problem was manageable. An unfortunate consequence of their paper, however, was to make the solution seem easy (see, e.g. [6, 7]). And in the meantime, the problem has grown. Since 2004, annual emissions have increased and their growth rate has accelerated, so that more than seven wedges would now be necessary to stabilize emissions and—more importantly—stabilizing emissions at current levels for 50 years does not appear compatible with Pacala and Socolow's target of an atmospheric CO2 concentration below 500 ppm nor the international community's goal of limiting the increase in global mean temperature to 2 °C more than the pre-industrial era. Here, we aim to revitalize the wedge concept by redefining what it means to 'solve the carbon and climate problem for the next 50 years'. This redefinition makes clear both the scale and urgency of innovating and deploying carbon-emissions-free energy technologies. 2. Solving the climate problem Stabilizing global climate requires decreasing CO2 emissions to near zero [8-11]. If emissions were to stop completely, global temperatures would quickly stabilize and decrease gradually over time [8, 12, 13]. But socioeconomic demands and dependence on fossil-fuel energy effectively commit us to many billions of tons of CO2 emissions [14], and at the timescale of centuries, each CO2 emission to the atmosphere contributes another increment to global warming: peak warming is proportional to cumulative CO2 emissions [15, 16]. Cumulative emissions, in turn, integrate all past emissions as well as those occurring during three distinct phases of mitigation: (1) slowing growth of emissions, (2) stopping growth of emissions, and (3) reducing emissions. Although they noted that stabilizing the climate would require emissions to 'eventually drop to zero', Pacala and Socolow nonetheless defined 'solv[ing] the carbon and climate problem over the next half-century' as merely stopping the growth of emissions (phases 1 and 2). Further reductions (phase 3), they said, could wait 50 years if the level of emissions were held constant in the meantime. But growth of emissions has not stopped (phase 2) or even slowed (phase 1), it has accelerated [17, 18]. In 2010, annual CO2 emissions crested 9 GtC. At this level, holding emissions constant for 50 years (phase 2) is unlikely to be sufficient to avoid the benchmark targets of 500 ppm or 2 °C. To support this assertion, we performed ensemble simulations using the UK Met Office coupled climate/carbon cycle model, HadCM3L (see supplementary material available at stacks.iop.org/ERL/8/011001/mmedia), to project changes in atmospheric CO2 and global mean temperature in response to emissions scenarios in which seven wedges (W7) and nine wedges (W9) were immediately subtracted from the A2 marker scenario of the Intergovernmental Panel on Climate Change (IPCC)'s Special Report on Emissions Scenarios (SRES) [19] beginning in 2010 (figure 1). In the first half of this century, the A2 scenario is near the center of the plume of variation of the SRES emissions scenarios [20]. Indeed, actual annual emissions have exceeded A2 projections for more than a decade [21, 22]. During this period, strong growth of global emissions has been driven by the rapid, carbon-intensive growth of emerging economies [23, 24], which has continued despite the global financial crisis of 2008-9 [18]. For these reasons we believe that, among the SRES scenarios, A2 represents a reasonable 'business-as-usual' scenario. However, if emissions were to suddenly decline and follow a lower emissions business-as-usual trajectory such as B2, fewer wedges would be necessary to stabilize emissions, and deployment of seven wedges would reduce annual emissions to 4.5 GtC in 2060. Thus, mitigation effort (wedges) required to stabilize emissions is dependent on the choice of baseline scenario, but a half-century of emissions at the current level will have the same effect on atmospheric CO2 and the climate regardless of what scenario is chosen. Figure 1 Figure 1. Modeled effects of deploying wedges. (A) Future CO2 emissions under SRES A2 marker scenario and the A2 scenario reduced by deployment of 7 wedges (W7). The response of (B) atmospheric CO2 and (C) global mean surface temperature under W7. (D) Future CO2 emissions under SRES A2 marker scenario and stabilized at 2010 levels (reduced by approximately 9 wedges relative to the A2 scenario) (W9). The response of (E) atmospheric CO2 and (F) global mean surface temperature under W9. Error bars in ((C) and (F)) are 2-sigma. Dashed lines in (A), (B), (D) and (E) show emissions and concentrations of representative concentration pathways RCP4.5, RCP6, and RCP8.5 [38]. Mean temperatures reflect warming relative to the pre-industrial era. We also note that the climate model we used, HadCM3L, has a strong positive climate/carbon cycle feedback mainly associated with the dieback of the Amazon rainforest [25]. As a result, HadCM3L projected the highest level of atmospheric CO2 concentrations among eleven Earth system models that were driven by a certain CO2 emission scenario [26]. However, this strong positive climate/carbon cycle feedback operates in simulations of both the A2 and wedge (W7 and W9) scenarios. Therefore, the relative effect of wedges, as opposed to the absolute values of projected atmospheric CO2 and temperature, is expected to be less dependent on the strength of climate/carbon cycle feedback. Atmospheric CO2 concentration and mean surface temperatures continue to rise under the modeled W7 scenario (figures 1(A)-(C)). Deploying 7 wedges does not alter projected mean surface temperatures by a statistically significant increment until 2046 (α = 0.05 level), at which time the predicted difference between mean temperatures in the A2 and W7 scenarios is 0.14 ± 0.08 °C. In 2060, the difference in projected mean temperatures under the two scenarios is 0.47 ± 0.07 °C. Further, under the W7 scenario, our results indicate atmospheric CO2 levels will exceed 500 ppm in 2042 (reaching 567 ± 1 ppm in 2060) (figure 1(B)), and 2 °C of warming in 2052 (figure 1(C)). Immediately stabilizing global emissions at 2010 levels (~10.0 GtCy-1), which would require approximately nine wedges (thus W9) under the A2 scenario, has a similarly modest effect on global mean surface temperatures and atmospheric CO2, with warming of 1.92 ± 0.4 °C in 2060 and atmospheric CO2 exceeding 500 ppm by 2049 (figures 1(D)-(F)). Our projections therefore indicate that holding emissions constant at current levels for the next half-century would cause substantial warming, approaching or surpassing current benchmarks [27-29] even before any reduction of emissions (phase 3) begins. Insofar as current climate targets accurately reflect the social acceptance of climate change impacts, then, solving the carbon and climate problem means not just stabilizing but sharply reducing CO2 emissions over the next 50 years. We are not alone in drawing this conclusion (see, e.g. [30-32]). For example, at least some integrated assessment models have now found that the emissions reductions required to prevent atmospheric CO2 concentration from exceeding 450 ppm are no longer either physically or economically feasible [11, 33, 34], and that preventing CO2 concentration from exceeding 550 ppm will also be difficult if participation of key countries such as China and Russia is delayed [11]. Most model scenarios that allow CO2 concentrations to stabilize at 450 ppm entail negative carbon emissions, for example by capturing and storing emissions from bioenergy [11]. A different body of literature has concluded that cumulative emissions of 1 trillion tons of carbon (i.e. 1000 GtC) are likely to result in warming of 2 °C [15, 35]. Whereas Pacala and Socolow's original proposal implied roughly 944 GtC of cumulative emissions (305 GtC prior to 2004, 389 GtC between 2004 and 2054, and another 250 GtC between 2054 and 2104 if emissions decrease at 2% y-1 as they suggested), stabilizing emissions at 2010 levels for 50 y and decreasing at 2% y-1 afterward increases the cumulative total to 1180 GtC of emissions (356 GtC prior to 2010, 491 GtC between 2010 and 2060, and 336 GtC between 2060 and 2110 at which time annual emissions remain at nearly 3.2 GtC y-1). Lastly, we note that even though emissions in the lowest of the new representative concentration pathways (RCP2.6) peak in 2020 at just 10.3 GtC y-1 and decline sharply to only 2.0 GtC y-1 in 2060 (figure 2), the concentration of atmospheric CO2 nonetheless reaches 443 ppm in 2050 [36-38]. In contrast, emissions of the intermediate pathway RCP4.5 rise modestly to 11.5 GtC y-1 in 2040 before declining to 9.6 GtC y-1 in 2060, which leads to atmospheric CO2 concentrations of 509 ppm in 2060 on the way to 540 ppm in 2100. These pathways, along with the integrated assessment models and cumulative emissions simulations all support our finding that 50 y of current emissions is not a solution to climate change. Figure 2 Figure 2. Idealization of future CO2 emissions under the business-as-usual SRES A2 marker scenario. Future emissions are divided into hidden (sometimes called 'virtual') wedges (brown) of emissions avoided by expected decreases in the carbon intensity of GDP by ~1% per year, stabilization wedges (green) of emissions avoided through mitigation efforts that hold emissions constant at 9.8 GtC y-1 beginning in 2010, phase-out wedges (purple) of emissions avoided through complete transition of technologies and practices that emit CO2 to the atmosphere to ones that do not, and allowed emissions (blue). Wedges expand linearly from 0 to 1 GtC y-1 from 2010 to 2060. The total avoided emissions per wedge is 25 GtC, such that altogether the hidden, stabilization and phase-out wedges represent 775 GtC of cumulative emissions. Unless current climate targets are sacrificed, solving the climate problem requires significantly reducing emissions over the next 50 years. Just how significant those reductions need to be will depend on a global trade-off between the damages imposed by climatic changes and the costs of avoiding them. But given substantial uncertainties associated with climate model projections (e.g., climate sensitivity), the arbitrary nature of targets like 500 ppm and 2 °C, and the permanence implied by the term 'solution', the ultimate solution to the climate problem is a complete phase-out of carbon emissions. 3. Counting wedges But significantly reducing current emissions while also sustaining historical growth rates of the global economy is likely to require many more than seven wedges. Gross world product (GWP) projections embedded in the A2 scenario imply as many as 31 wedges would be required to completely phase-out emissions, grouped into three distinct groups: (1) 12 'hidden' wedges that represent the continued decarbonization of our energy system at historical rates (i.e. decreases in the carbon intensity of the global economy that are assumed to regardless of any additional efforts to mitigate emissions) [9, 39]. (2) 9 'stabilization' wedges that represent additional efforts to mitigate emissions above and beyond the technological progress already assumed by the scenario [1]. And (3), 10 'phase-out' wedges that represent the complete transition from energy infrastructure and land-use practices that emit CO2 (on net) to the atmosphere to infrastructure and practices which do not (figure 2) [9, 14, 40]. There is good reason to be concerned that at least some number of the hidden wedges will not come to be—that the rates of decarbonization assumed by almost all scenarios of future emissions may underestimate the extent to which rising energy demand will be met by increased use of coal and unconventional fossil fuels [24, 41]. Moreover, there is no way to know whether a wedge created by deploying carbon-free energy technology represents additional mitigation effort (i.e. a stabilization wedge) or something that would have happened in the course of normal technological progress (i.e. a hidden wedge). Thus, in assessing the efficacy of efforts to reduce emissions, it may be more useful to tabulate wedges based only on the current carbon intensity of global energy and food production and projected demand for energy and food, without reference to any particular technology scenario. Doing so would clarify the full level of decarbonization necessary and remove the question of whether emissions reductions that do occur should count as mitigation or not. But even assuming that historical rates of decarbonization will persist and therefore that many hidden wedges will materialize, phasing-out emissions altogether will entail nearly three times the number of additional wedges that Pacala and Socolow originally proposed—a total of 19 wedges under the A2 scenario (figure 2). 4. The urgent need for innovation Confronting the need for as many as 31 wedges (12 hidden, 9 stabilization and 10 phase-out), the question is whether there are enough affordable mitigation options available, and—because the main source of CO2 emissions is the burning of fossil fuels—the answer depends upon an assessment of carbon-free energy technologies. There is a longstanding disagreement in the literature between those who argue that existing technologies, improved incrementally, are all that is needed to solve the climate problem (e.g. [1]) and others who argue that more transformational change is necessary (e.g. 42]). Although the disagreement has turned on the definitions of incremental and transformative and the trade-offs of a near-term versus a longer-term focus, the root difference lies in the perceived urgency of the climate problem [6]. The emission reductions required by current targets, let alone a complete phase-out of emissions, demand fundamental, disruptive changes in the global energy system over the next 50 years. Depending on what sort of fossil-fuel infrastructure is replaced and neglecting any emissions produced to build and maintain the new infrastructure (see, e.g. [43]), a single wedge represents 0.7-1.4 terawatts (TW) of carbon-free energy (or an equivalent decrease in demand for fossil energy). Whether the changes to the energy system are called incremental or revolutionary, few would dispute that extensive innovation of technologies will be necessary to afford many terawatts of carbon-free energy and reductions in energy demand [42, 44, 45]. Currently, only a few classes of technologies might conceivably provide carbon-free power at the scale of multiple terawatts, among them fossil fuels with carbon capture and storage (CCS), nuclear, and renewables (principally solar and wind, and perhaps biomass) [42, 46, 47]. However, CCS has not yet been commercially deployed at any centralized power plant; the existing nuclear industry, based on reactor designs more than a half-century old and facing renewed public concerns of safety, is in a period of retrenchment, not expansion; and existing solar, wind, biomass, and energy storage systems are not yet mature enough to provide affordable baseload power at terawatt scale. Each of these technologies must be further developed if they are to be deployed at scale and at costs competitive with fossil energy. Yet because investments in the energy sector tend to be capital intensive and long term, research successes are often not fully appropriable [48], and technologies compete almost entirely on the price of delivered electricity, private firms tend to underinvest in R&D, which has made energy one of the least innovative industry sectors in modern economies [44]. Supporting deployment of newer energy technologies at large scales will undoubtedly lead to further development and reduced costs [49, 50], but additional public support for early stage R&D will also be necessary to induce needed innovation [6, 44, 45, 51-53]. Moreover, it is imperative that policies and programs also address the intermediate stages of development, demonstration, and commercialization, when ideas born of public-funded research must be transferred to and diffused among private industries [44, 54, 55]. 5. Conclusions In 2004, Pacala and Socolow concluded that 'the choice today is between action and delay'. After eight years of mostly delay, the action now required is significantly greater. Current climate targets of 500 ppm and 2 °C of warming will require emissions to peak and decline in the next few decades. Solving the climate problem ultimately requires near-zero emissions. Given the current emissions trajectory, eliminating emissions over 50 years would require 19 wedges: 9 to stabilize emissions and an additional 10 to completely phase-out emissions. And if historical, background rates of decarbonization falter, 12 'hidden' wedges will also be necessary, bringing the total to a staggering 31 wedges. Filling this many wedges while sustaining global economic growth would mean deploying tens of terawatts of carbon-free energy in the next few decades. Doing so would entail a fundamental and disruptive overhaul of the global energy system, as the global energy infrastructure is replaced with new infrastructure that provides equivalent amounts of energy but does not emit CO2. Current technologies and systems cannot provide the amounts of carbon-free energy needed soon enough or affordably enough to achieve this transformation. An integrated and aggressive set of policies and programs is urgently needed to support energy technology innovation across all stages of research, development, demonstration, and commercialization. No matter the number required, wedges can still simplify and quantify the challenge. But the problem was never easy. Acknowledgments We thank six anonymous reviewers for their comments on various versions of the manuscript. We also especially thank R Socolow for several thoughtful and stimulating discussions of this work.

CO2 solubility and speciation in rhyolitic sediment partial melts at 1.5-3.0 GPa - Implications for carbon flux in subduction zones

NASA Astrophysics Data System (ADS)

Duncan, Megan S.; Dasgupta, Rajdeep

2014-01-01

Partial melts of subducting sediments are thought to be critical agents in carrying trace elements and water to arc basalt source regions. Sediment partial melts may also act as a carrier of CO2. However, the CO2 carrying capacity of natural rhyolitic melts that derive from partial fusion of downgoing sediment at sub-arc depths remains unconstrained. We conducted CO2-solubility experiments on a rhyolitic composition similar to average, low-degree experimental partial melt of pelitic sediments between 1.5 and 3.0 GPa at 1300 °C and containing variable water content. Concentrations of water and carbon dioxide were measured using FTIR. Molecular CO2(CO2mol.) and carbonate anions (CO32-) both appear as equilibrium species in our experimental melts. Estimated total CO2 concentrations (CO2mol.+CO32-) increased with increasing pressure and water content. At 3.0 GPa, the bulk CO2 solubility are in the range of ∼1-2.5 wt.%, for melts with H2O contents between 0.5 and 3.5 wt.%. For melts with low H2O content (∼0.5 wt.%), CO2mol. is the dominant carbon species, while in more H2O-rich melts CO32- becomes dominant. The experimentally determined, speciation-specific CO2 solubilities yielded thermodynamic parameters that control dissolution of CO2 vapor both as CO2mol. and as CO32- in silicate melt for each of our compositions with different water content; CO2vapor ↔CO2melt :lnK0=-15 to -18, ΔV0 = 29 to 14 cm3 mol-1 and CO2vapor +Omelt →CO32-melt :lnK0=-20 to -14, ΔV0 = 9 to 27 cm3 mol-1, with ΔV0 of reaction being larger for formation of CO2mol. in water-poor melts and for formation of CO32- in water-rich melts. Our bulk CO2 solubility data, [CO2] (in wt.%) can be fitted as a function of pressure, P (in GPa) and melt water content, [H2O] (in wt.%) with the following function: [CO2](wt.%)=(-0.01108[H2O]+0.03969)P2+(0.10328[H2O]+0.41165)P. This parameterization suggests that over the range of sub-arc depths of 72-173 km, water-rich sediment partial melt may carry as much as 2.6-5.5 wt.% CO2 to the sub-arc mantle source regions. At saturation, 1.6-3.3 wt.% sediment partial melt relative to the mantle wedge is therefore sufficient to bring up the carbon budget of the mantle wedge to produce primary arc basalts with 0.3 wt.% CO2. Sediment plumes in mantle wedge: Sediment plumes or diapirs may form from the downgoing slab because the sediment layer atop the slab is buoyant relative to the overlying, hanging wall mantle (Currie et al., 2007; Behn et al., 2011). Via this process, sediment layers with carbonates would carry CO2 to the arc source region. Owing to the higher temperature in the mantle wedge, carbonate can breakdown. Behn et al. (2011) suggested that sediment layers as thin as 100 m, appropriate for modern arcs, could form sediment diapirs. They predicted that diapirs would form from the slab in the sub-arc region for most subduction zones today without requiring hydrous melting. H2O-rich fluid driven carbonate breakdown: Hydrous fluid flushing of the slab owing to the breakdown of hydrous minerals could drive carbonate breakdown (Kerrick and Connolly, 2001b; Grove et al., 2002; Gorman et al., 2006). The addition of water would cause decarbonation creating an H2O-CO2-rich fluid that would then flux through the overlying sediment layer, lower the solidus temperature, and trigger melting. Recent geochemical (Cooper et al., 2012) and geodynamic (van Keken, 2003; Syracuse et al., 2010) constraints suggest that the sub-arc slab top temperatures are above the hydrous fluid-present sediment solidus, thus in the presence of excess fluid, both infiltration induced decarbonation and sediment melting may occur. Hot subduction: This is relevant for subduction zones such as Cascadia and Mexico, where slab-surface temperatures are estimated to be higher (Syracuse et al., 2010). A higher temperature could cause carbonate breakdown and sediment partial melting without requiring a hydrous fluid flux. In this case a relatively dry silicate sediment melt will have the opportunity to dissolve and carry CO2. For hot subduction zones, even if sedimentary layer itself does not carry carbonate, CO2 released from basalt-hosted carbonates may be dissolved in sediment partial melt. Experiments conducted on subducted sediment compositions show that the partial melt compositions are generally rhyolitic (Johnson and Plank, 1999; Hermann and Green, 2001; Schmidt et al., 2004; Auzanneau et al., 2006; Hermann and Spandler, 2008; Spandler et al., 2010; Tsuno and Dasgupta, 2011). Therefore, solubility of CO2 in rhyolitic sediment partial melts needs to be known. Previous studies on rhyolitic melts experimentally determined CO2 solubility from 0.05 to 0.66 GPa (Fig. 1; Fogel and Rutherford, 1990; Blank et al., 1993; Tamic et al., 2001). This pressure range is not appropriate for global sub-arc depth range of 72-173 km (Syracuse and Abers, 2006) settings (P = 2-5 GPa). Carbon dioxide solubility experiments at pressures from 1.5 to 3.5 GPa are available but only on simple compositions - i.e., albite, which does not have the chemical complexity of natural sediment partial melts (Fig. 1; Brey, 1976; Mysen, 1976; Mysen et al., 1976; Mysen and Virgo, 1980; Stolper et al., 1987; Brooker et al., 1999). For example, natural rhyolitic melt derived from partial fusion of pelitic sediments contain non-negligible concentrations of Ca2+, Mg2+, Fe2+. Many of these studies were also conducted under mixed-volatile conditions (CO2 + H2O) with H2O contents from 0.06 to 3.3 wt.%. These studies were used in calculating various solubility models: Volatile-Calc (Newman and Lowenstern, 2002), that of Liu et al. (2005), and that of Papale et al. (2006). Volatile-Calc can be used to calculate CO2 solubility only on a generic rhyolite composition up to 0.5 GPa. The model of Liu et al. (2005) is also on a generic rhyolite up to 0.5 GPa, but can calculate mixed volatile concentrations provided the vapor composition is known. The model of Papale et al. (2006) can be used to calculate mixed volatile concentrations for a melt composition of interest, but only up to 1.0 GPa.The literature data show that CO2 solubility increases with increasing pressure and decreases with increasing melt silica content (decreasing NBO/T; e.g., Brooker et al., 2001). The effect of temperature remains somewhat ambiguous, but is thought to be relatively smaller than the pressure or compositional effects, with Mysen (1976) measuring increasing CO2 solubility with temperature for albite melt, Brooker et al. (2001) and Fogel and Rutherford (1990) noticing decreasing CO2 solubility with increasing temperature, and Stolper et al. (1987) concluding that temperature has essentially no effect on total melt CO2 concentration at saturation. The presence of water in the melt also is known to affect CO2 solution (e.g., Mysen, 1976; Eggler and Rosenhauer, 1978), yet quantitative effect of water on CO2 solution in natural rhyolitic melt has only been investigated up to 0.5 GPa (Tamic et al., 2001). In order to determine the CO2 carrying capacity of sediment partial melts, experiments must be conducted at conditions (pressure, temperature, major element compositions, and XH2O) relevant to sub-arc settings.In this study we measured the solubility and speciation of CO2 in rhyolitic sediment partial melts. Experiments were conducted from 1.5 to 3.0 GPa at 1300 °C with variable water contents and synthesized glasses were analyzed for water and carbon speciation using Fourier-transformed infrared spectroscopy. Our measured solubility data allowed us to constrain volume change and equilibrium constant of the CO2 dissolution reactions. Moreover, we parameterize CO2 solubility in sediment partial melt as a function of pressure and melt water content. Our data and empirical model suggest that the CO2 carrying capacity of sediment partial melts is sufficiently high at sub-arc depths and hydrous sediment melt can potentially carry the necessary dose of CO2 to arc mantle source regions.

Multiscale modeling and experimental interpretation of perovskite oxide materials in thermochemical energy storage and conversion for application in concentrating solar power

NASA Astrophysics Data System (ADS)

Albrecht, Kevin J.

Decarbonization of the electric grid is fundamentally limited by the intermittency of renewable resources such as wind and solar. Therefore, energy storage will play a significant role in the future of grid-scale energy generation to overcome the intermittency issues. For this reason, concentrating solar power (CSP) plants have been a renewable energy generation technology of interest due to their ability to participate in cost effective and efficient thermal energy storage. However, the ability to dynamically dispatch a CSP plant to meet energy demands is currently limited by the large quantities of sensible thermal energy storage material needed in a molten salt plant. Perovskite oxides have been suggested as a thermochemical energy storage material to enhance the energy storage capabilities of particle-based CSP plants, which combine sensible and chemical modes of energy storage. In this dissertation, computational models are used to establish the thermochemical energy storage potential of select perovskite compositions, identify system configurations that promote high values of energy storage and solar-to-electric efficiency, assess the kinetic and transport limitation of the chemical mode of energy storage, and create receiver and reoxidation reactor models capable of aiding in component design. A methodology for determining perovskite thermochemical energy storage potential is developed based on point defect models to represent perovskite non-stoichiometry as a function of temperature and gas phase oxygen partial pressure. The thermodynamic parameters necessary for the model are extracted from non-stoichiometry measurements by fitting the model using an optimization routine. The procedure is demonstrated for Ca0.9Sr0.1MnO 3-d which displayed combined energy storage values of 705.7 kJ/kg -1 by cycling between 773 K and 0.21 bar oxygen to 1173 K and 10 -4 bar oxygen. Thermodynamic system-level models capable of exploiting perovskite redox chemistry for energy storage in CSP plants are presented. Comparisons of sweep gas and vacuum pumping reduction as well as hot storage conditions indicate that solar-to-electric efficiencies are higher for sweep gas reduction system at equivalent values of energy storage if the energy parasitics of commercially available devices are considered. However, if vacuum pump efficiency between 15% and 30% can be achieved, the reduction methods will be approximately equal. Reducing condition oxygen partial pressures below 10-3 bar for sweep gas reduction and 10-2 bar for vacuum pumping reduction result in large electrical parasitics, which significantly reduce solar-to-electric efficiency. A model based interpretation of experimental measurements made for perovskite redox cycling using sweep gas in a packed bed is presented. The model indicates that long reduction times for equilibrating perovskites with low oxygen partial pressure sweep gas, compared to reoxidation, are primarily due to the oxygen carrying capacity of high purity sweep gas and not surface kinetic limitations. Therefore, achieving rapid reduction in the limited receiver residence time will be controlled by the quantity of sweep gas introduced. Effective kinetic parameters considering surface reaction and radial particle diffusion are fit to the experimental data. Variable order rate expressions without significant particle radial diffusion limitations are shown to be capable of representing the reduction and oxidation data. Modeling of a particle reduction receiver using continuous flow of perovskite solid and sweep gas in counter-flow configuration has identified issues with managing the oxygen evolved by the solid as well as sweep gas flow rates. Introducing sweep gas quantities necessary for equilibrating the solid with oxygen partial pressures below 10-2 are shown to result in gas phase velocities above the entrainment velocity of 500 um particles. Receiver designs with considerations for gas management are investigated and the results indicate that degrees of reduction corresponding to only oxygen partial pressures of 10-2 bar are attained. Numerical investigation into perovskite thermochemical energy storage indicates that achieving high levels of reduction through sweep gas or vacuum pumping to lower gas phase oxygen partial pressure below 10-2 bar display issues with parasitic energy consumption and gas phase management. Therefore, focus on material development should place a premium on thermal reduction and reduction by shifting oxygen partial pressure between ambient and 10-2 bar. Such a material would enable the development of a system with high solar-to-electric efficiencies and degrees of reduction which are attainable in realistic component geometries.

Geophysical, petrological and mineral physics constraints on Earth's surface topography

NASA Astrophysics Data System (ADS)

Guerri, Mattia; Cammarano, Fabio; Tackley, Paul J.

2015-04-01

Earth's surface topography is controlled by isostatically compensated density variations within the lithosphere, but dynamic topography - i.e. the topography due to adjustment of surface to mantle convection - is an important component, specially at a global scale. In order to separate these two components it is fundamental to estimate crustal and mantle density structure and rheological properties. Usually, crustal density is constrained from interpretation of available seismic data (mostly VP profiles) based on empirical relationships such those in Brocher [2005]. Mantle density structure is inferred from seismic tomography models. Constant coefficients are used to interpret seismic velocity anomalies in density anomalies. These simplified methods are unable to model the effects that pressure and temperature variations have on mineralogical assemblage and physical properties. Our approach is based on a multidisciplinary method that involves geophysical observables, mineral physics constraints, and petrological data. Mantle density is based on the thermal interpretation of global seismic tomography models assuming various compositional structures, as in Cammarano et al. [2011]. We further constrain the top 150 km by including heat-flow data and considering the thermal evolution of the oceanic lithosphere. Crustal density is calculated as in Guerri and Cammarano [2015] performing thermodynamic modeling of various average chemical compositions proposed for the crust. The modeling, performed with the code PerpleX [Connolly, 2005], relies on the thermodynamic dataset from Holland and Powell [1998]. Compressional waves velocity and crustal layers thickness from the model CRUST 1.0 [Laske et al., 2013] offer additional constrains. The resulting lithospheric density models are tested against gravity (GOCE) data. Various crustal and mantle density models have been tested in order to ascertain the effects that uncertainties in the estimate of those features have on the modeled topography. We also test several viscosity models, either radially symmetric, the V1 profile from Mitrovica and Forte [2004], or more complex laterally varying structures. All the property fields are expanded in spherical harmonics, until degree 24, and implemented in the code StagYY [Tackley, 2008] to perform mantle instantaneous flow modeling and compute surface topography and gravitational field. Our results show the importance of constraining the crustal and mantle density structure relying on a multidisciplinary approach that involves experimentally robust thermodynamic datasets. Crustal density field has a strong effect on the isostatic component of topography. The models that we test, CRUST 1.0 and those in Guerri and Cammarano [2015], produce strong differences in the computed isostatic topography, in the range ±600 m. For the lithospheric mantle, relying on experimentally robust material properties constraints is necessary to infer a reliable density model that takes into account chemical heterogeneities. This approach is also fundamental to correctly interpret seismic models in temperature, a crucial parameter, necessary to determine the lithosphere-asthenosphere boundary, where static effects on topography leave place to dynamic ones. The comparison between results obtained with different viscosity fields, either radially symmetric or vertically and laterally varying, shows how lateral viscosity variations affect the results, in particular the modeled geoid, at different wavelengths. References: Brocher, T. M. (2005), Empirical Relations between Elastic Wavespeeds and Density in the Earth's Crust, Bulletin of the Seismological Society of America, 95(6), 2081-2092. Cammarano, F., P. J. Tackley, and L. Boschi (2011), Seismic, petrological and geodynamical constraints on thermal and compositional structure of the upper mantle: global thermochemical models, Geophys. J. Int. Connolly, J. A. D. (2005), Computation of phase equilibria by linear programming: A tool for geodynamic modeling and its application to subduction zone decarbonation, Earth and Planetary Science Letters (236), 524-541. Guerri, M., and F. Cammarano (2015), On the effects of chemical composition, water and temperature on physical properties of the Earth's continental crust, submitted to Geochemistry, Geophysics, Geosystem. Holland, T. J. B., and R. Powell (1998), An internally consistent thermodynamic data set for phases of petrological interest, J. metamorphic Geol., 16(309-343). Laske, G., G. Masters, Z. Ma, and M. E. Pasyanos (2013), CRUST1.0: An updated global model of Earth's crust, in EGU General Assembly 2013, edited, Geophysical Research Abstracts, Vienna. Mitrovica, J. X., and A. M. Forte (2004), A new inference of mantle viscosity based upon joint inversion of convection and glacial isostatic adjustment data, Earth and Planetary Science Letters, 225, 177-189. Tackley, P. J. (2008), Modelling compressible mantle convection with large viscosity contrasts in a three-dimensional spherical shell using the yin-yang grid, Phys. Earth Planet. Int.

A synthesis of mineralization styles with an integrated genetic model of carbonatite-syenite-hosted REE deposits in the Cenozoic Mianning-Dechang REE metallogenic belt, the eastern Tibetan Plateau, southwestern China

NASA Astrophysics Data System (ADS)

Liu, Yan; Hou, Zengqian

2017-04-01

The Cenozoic Mianning-Dechang (MD) rare earth element (REE) belt in eastern Tibet is an important source of light REE in southwest China. The belt is 270 km long and 15 km wide. The total REE resources are >3 Mt of light rare earth oxides (REO), including 3.17 Mt of REO at Maoniuping (average grade = 2.95 wt.%), 81,556 t at Dalucao (average grade = 5.21 wt.%), 0.1 Mt at Muluozhai (average grade = 3.97 wt.%), and 5764 t of REO at Lizhuang (average grade = 2.38 wt.%). Recent results from detailed geological surveys, and studies of petrographic features, ore-forming ages, ore forming conditions, and wallrock alteration are synthesized in this paper. REE mineralization within this belt is associated with carbonatite-syenite complexes, with syenites occurring as stocks intruded by carbonatitic sills or dikes. The mineralization is present as complex vein systems that contain veinlet, stringer, stockwork, and brecciated pipe type mineralization. Carbonatites in these carbonatite-related REE deposits (CARDs) are extremely rich in light REEs, Sr (>5000 ppm), and Ba (>1000 ppm), and have low Sr/Ba and high Ba/Th ratios, and radiogenic Sr-Nd isotopic compositions. These fertile magmas, which may lead to the formation of REE deposits, were generated by the partial melting of sub-continental lithospheric mantle (SCLM) that was metasomatized by REE- and CO2-rich fluids derived from subducted marine sediments. We suggest that this refertilization occurred along cratonic margins and, in particular, at a convergent margin where small-volume carbonatitic melts ascended along trans-lithospheric faults and transported REEs into the overlying crust, leading to the formation of the CARDs. The formation of fertile carbonatites requires a thick lithosphere and/or high pressures (>25 kbar), a metasomatized and enriched mantle source, and favorable pathways for magma to ascend into the overlying crust where REE-rich fluids exsolve from cooling magma. The optimal combination of these three factors only occurs along the margins of a craton with a continental root, rather than in modern subduction zones where the lithosphere is relatively thin. U-Pb zircon dating indicates that the Maoniuping, Lizhuang, and Muluozhai alkali igneous complexes in the northern part of the belt formed at 27-22 Ma, whereas the Dalucao complex in the southern part of the belt formed at 12-11 Ma. Biotite and arfvedsonite in Lizhuang and Maoniuping REE deposit have 40Ar/39Ar ages of 30.8 ± 0.4 Ma (MSWD = 0.98) and 27.6 ± 2.0 Ma (MSWD = 0.06), respectively. Biotitaion alteration in syenite and fenitization caused by the relatively amount of carbonatite on syenite and host rocks is the main alteration along the whole belt. Initial Sr (0.7059-0.7079), 143Nd/144Nd (0.5123-0.5127), and 207Pb/204Pb (15.601-15.628) and 208Pb/204Pb (38.422-38.604) isotopic compositions of fluorite, barite, celestite, and calcite in the MD belt are similar to those of the associated syenite and carbonatite. Given the relatively high contents of Cl, F, SO42-, and CO2 in the rocks of the complexes, it is likely that the REEs were transported by these ligands within hydrothermal fluids, and the presence of bastnäsite indicates that the REEs were precipitated as fluorocarbonates. Petrographic, fluid inclusion, and field studies of the ores indicate that bastnäsite and other REE minerals formed during the final stages (<300 °C) of the evolution of magmatic-hydrothermal systems in the belt. The mineralization formed from magmatic and meteoric fluids containing CO2 derived from the decarbonation of carbonatite, as indicated by C-O isotopic values of hydrothermal calcite and bastnäsite (δ13C = -4.8 to -8.7 and δ18O = 5.8 to 12.5‰) and O-H isotopic values of quartz (330 °C) and arfvedsonite (260 °C), which correspond to fluid isotope compositions of δ18O = 0.3-9.8‰ and δD = -70.0 to -152.8‰ in the belt. This study indicates that formation the largest REE deposits are related to voluminous carbonatite-syenite complexes, compositionally similar ore-forming fluids, extensive alteration, multiple stages of REE mineralization, and tectonic setting.

The contribution of weathering of the main Alpine rivers on the global carbon cycle

NASA Astrophysics Data System (ADS)

Donnini, Marco; Probst, Jean-Luc; Probst, Anne; Frondini, Francesco; Marchesini, Ivan; Guzzetti, Fausto

2013-04-01

On geological time-scales the carbon fluxes from the solid Earth to the atmosphere mainly result from volcanism and metamorphic-decarbonation processes, whereas the carbon fluxes from atmosphere to solid Earth mainly depend on weathering of silicates and carbonates, biogenic precipitation and removal of CaCO3 in the oceans and volcanic gases - seawater interactions. Quantifying each contribution is critical. In this work, we estimate the atmospheric CO2 uptake by weathering in the Alps, using results of the study of the dissolved loads transported by 33 main Alpine rivers. The chemical composition of river water in unpolluted areas is a good indicator of surface weathering processes (Garrels and Mackenzie, 1971; Drever, 1982; Meybeck, 1984; Tardy, 1986; Berner and Berner, 1987; Probst et al., 1994). The dissolved load of streams originates from atmospheric input, pollution, evaporite dissolution, and weathering of carbonate and silicate rocks, and the application of mass balance calculations allows quantification of the different contributions. In this work, we applied the MEGA (Major Element Geochemical Approach) geochemical code (Amiotte Suchet, 1995; Amiotte Suchet and Probst, 1996) to the chemical compositions of the selected rivers in order to quantify the atmospheric CO2 consumed by weathering in Alpine region. The drainage basins of the main Alpine rivers were sampled near the basin outlets during dry and flood seasons. The application of the MEGA geochemical consisted in several steps. First, we subtracted the rain contribution in river waters knowing the X/Cl (X = Na, K, Mg, Ca) ratios of the rain. Next, we considered that all (Na+K) came from silicate weathering. The average molar ratio Rsil = (Na+K)/(Ca+Mg) for rivers draining silicate terrains was estimated from unpolluted French stream waters draining small monolithological basins (Meybeck, 1986; 1987). For the purpose, we prepared a simplified geo-lithological map of Alps according to the lithological classification of Meybeck (1986, 1987). Then for each basin we computed Rsil weighted average considering the surface and the mean precipitation for the surface area of each lithology. Lastly, we estimated the (Ca+Mg) originating from carbonate weathering as the remaining cations after silicate correction. Depending on time-scales of the phenomena (shorter than about 1 million year i.e., correlated to the short term carbon cycle, or longer than about 1 million years i.e., correlated to the long-term carbon cycle), we considered different equations for the quantification of the atmospheric CO2 consumed by weathering (Huh, 2010). The results show the net predominance of carbonate weathering on fixing atmospheric CO2 and that, considering the long-term carbon cycle, the amount of atmospheric CO2 uptake by weathering is about one order of magnitude lower than considering the short-term carbon cycle. Moreover, considering the short-term carbon cycle, the mean CO2 consumed by Alpine basins is of the same order of magnitude of the mean CO2 consumed by weathering by the 60 largest rivers of the world estimated by Gaillardet et al. (1999). References Amiotte-Suchet, P. "Cycle Du Carbone, Érosion Chimique Des Continents Et Transfert Vers Les Océans." Sci. Géol. Mém. Strasbourg 97 (1995): 156. Amiotte-Suchet, P., and J.-L. Probst. "Origins of dissolved inorganic carbon in the Garonne river waters: seasonal and interannual variations." Sci. Géologiques Bull. Strasbourg 49, no. 1-4 (1996): 101-126. Berner, E.K., and R.A. Berner. The Global Water Cycle. Geochemistry and Environment. Prentice Halle. Engelwood Cliffs, NJ, 1987. Drever, J.L. The Geochemistry of Natural Waters. Prentice Hall, 1982. Gaillardet, J., B. Dupré, P. Louvat, and C.J. Allègre. "Global Silicate Weathering and CO2 Consumption Rates Deduced from the Chemistry of Large Rivers." Chemical Geology 159 (1999): 3-30. Garrels, R.M., and F.T. Mackenzie. Evolution of Sedimentary Rocks. New York: W.W. Nortonand, 1971. Huh, Y. "Estimation of Atmospheric CO2 Uptake by Silicate Weathering in the Himalayas and the Tibetan Plateau: a Review of Existing Fluvial Geochemical Data." In Monsoon Evolution and Tectonics-Climate Linkage in Asia, 129-151. Geological Society of London, Special Publications. 342. London, 2010. Meybeck, M. "Composition Chimique Naturelle Des Ruisseaux Non Pollués En France." Bullettin De La Société Géologique 39 (1986): 3-77. Meybeck, M. "Global Chemical Weathering of Surficial Rocks Estimated from River Dissolved Load." Am. J. Sci 287 (1987): 401-428. Probst J.L., Mortatti J. And Tardy Y. 1994- Carbon river fluxes and global weathering CO2 consumption in the Congo and Amazon river basins. Applied Geochemistry, 9, p 1-13 Tardy, Y. Le Cycle De l'Eau. Climats, Paléoclimates Et Géochimie Globale. Masson. Paris, 1986.

An estimation of Central Iberian Peninsula atmospheric δ13C and water δD in the Upper Cretaceous using pyrolysis compound specific isotopic analysis (Py-CSIA) of a fossil conifer.

NASA Astrophysics Data System (ADS)

González-Pérez, José A.; Jiménez-Morillo, Nicasio T.; De la Rosa, José M.; Almendros, Gonzalo; González-Vila, Francisco J.

2015-04-01

Frenelopsis is a frequently found genus of the Cretaceous floras adapted to dry, saline and in general to environmental conditions marked by severe water stress [1]. Stable isotope analysis of fossil organic materials can be used to infer palaeoenvironmental variables helpful to reconstruct plant paleohabitats [2]. In this study stable isotope analysis of organic fossil remains (FR) and humic fractions (FA, HA and humin) of Frenelopsis oligiostomata are studied in bulk (C, H, O, N IRMS) and in specific compounds released by pyrolysis (C, H, Py-CSIA). Well preserved F. oligiostomata fossils were handpicked from a limestone included in compacted marls from Upper Cretaceous (Senonian c. 72 Mya) in Guadalix de la Sierra (Madrid, Spain) [3]. The fossils were decarbonated with 6M HCl. Humic substances were extracted from finely ground fossil remains (FR) by successive treatments with 0.1M Na4P2O7 + NaOH [4]. The extract was acidified resulting into insoluble HA and soluble FA fractions. The HA and FA were purified as in [5] and [6] respectively. Bulk stable isotopic analysis (δ13C, δD, δ18O, δ15N IRMS) was done in an elemental micro-analyser coupled to a continuous flow Delta V Advantage isotope ratio mass spectrometer (IRMS). Pyrolysis compound specific isotopic analysis Py-CSIA (δ13C, δD): was done by coupling a double-shot pyrolyzer to a chromatograph connected to an IRMS. Structural features of specific peaks were inferred by comparing/matching mass spectra from conventional Py-GC/MS (data not shown) with Py-GC/IRMS chromatograms obtained using the same chromatographic conditions. Bulk C isotopic signature found for FR (-20.5±0.02 ‰) was in accordance with previous studies [2, 7-9]. This heavy isotopic δ13C signature indicates a depleted stomatal conductance and paleoenvironmental growth conditions of water and salt stress. This is in line with the morphological and depositional characteristics [3] confirming that F. oligostomata was adapted to highly xeric and saline habitats being a component of salt-marsh vegetation. The values obtained for δD (-101.9±2.2 ‰), δ15N (10.7±0.2 ‰) and δ18O (20.9±0.39 ‰) lay within those previously reported for fossil floras [10] growing in warm environment and probably with very high evaporation rates. δ13C Py-CSIA was recorded for biogenic compound; polysaccharides, lipid series, lignin and degraded lignin compounds (alkyl benzenes and alkyl phenols) and for a S containing compounds probably with a diagenetic origin. In general δ13C Py-CSIA values were more depleted that the bulk ones and can be considered a better approach to the real plant δ13C value (c. -22 ‰). Considering that plant-air C fractionation in degraded lignin compounds for a C4 photosystem plant is c. Δ13C≈ 20.0 ‰ [11] and a an extra fractionation (Δ13C≈ -3.0 ‰) due to the plant depleted stomatal conductance growing in extreme warm, saline and dry conditions, we estimate atmospheric δ13C value in the area during the Upper Cretaceous in c. δ13C = -5.3±0.2 ‰. This indicates that our F.oligostomata probably grew on a 13C enriched atmosphere, more enriched than preindustrial one (δ13C ≈ -6.5 ‰; [12]). This could be caused by a combination of reasons i.e. emissions of heavy 13C isotope to the atmosphere by an increase in ocean's temperature and acidification by volcanic S depositions during this geologically active and warm period, and/or an increase of primary production and net terrestrial C uptake with selective removal of light 12C isotope by plants. Values for δD CSIA of lipid compounds such as n-alkanes with C chain lengths, C23-C31 are believed to derive exclusively from leaf waxes of higher plants. Plant δD carries isotope information of environmental water that is particularly preserved during the geological record in n-alkyl structures, whereas other structures i.e. isoprenoids, are most prone to hydrogen exchange [13-14]. We were able to measure δD for long chain alkane/alkene series in the range C24-C29 (δD = -124.44±5.2‰). This was taken as a proxy to infer the original H isotopic signal of water in the area in the Upper Cretaceous. Poole et al. (2004) proposed that δDpalaeowarter= δDC24-C29 n-alkanes + 100 giving a value for plaeowater δD = -24.44±5.2‰. This indicates that 75 Mya our plant probably uptake deuterium enriched rain water that again points to warm growing environmental conditions. (1) Gómez, B.; Martín-Closas C.; Brale G.; Solé de Porta N.; Thévenard F.; Guignard G. Paleontology 2002 45, 997-1036. (2) Nguyen Tu, T.T.; Kvaček, J.; Uličnỷ, D.; Bocherens, H.; Mariotti, A.; Broutin, J. Palaeogeogr. Palaeoclimatol. Palaeoecol. 2002 183, 43-70. (3) Almendros, G.; Álvarez-Ramis, C.; Polo, A. Revista de la Real Academia de Ciencias Exactas, Físicas y Naturales 1982 76, 285-302. (4) Dabin, B. Chah. ORSTOM Ser. Pedol. 1976 4, 287-297. (5) Schnitzer, M.; Khan, S.U. Humic Substances in the Environment. Marcel Dekker Inc. 1972, New York, N.Y. (6) Dorado, E.; Polo. A. An. Edafol. Agrobiol. 1976 55, 723-732. (7) Bocherens, H.; Friis, E.M.; Mariotti, A.; Pedersen, K.R. Lethaia 1993 26, 347-358. (8) Nguyen Tu, T.T.; Bocherens, H.; Mariotti, A.; Baudin, F.; Pons, D.; Broutin, J.; Derenne, S.; Largeau C. Palaeogeogr. Palaeoclimatol. Palaeoecol. 1999 145, 79-93. (9) Aucour, A-.M.; Gomez, B.; Sheppard, S.M.F., Thévenard, F. Palaeogeogr. Palaeoclimatol. Palaeoecol. 2008 257, 462-473. (10) Michener, N.; Lajtha K. (Eds). Stable Isotopes in Ecology and Environmental Science (2nd Ed) 2007 Blackwell Publishing. (11) Poole, I., van Bergen, P.F.; Kool, K.; Schouten , S.; Cantrill, D. J. Org. Geochem. 2004 35, 1261-1274. (12) Gerber, S.; Joos, F.; Brügger, P.; Stocker, T.F.; Mann, M.E.; Sitch, S.; Scholze, M. Clim. Dyn. 2003 20, 281-299, 2003 (13) Pedentchouk, N.; Freeman, K.H.; Harris, N.B. Geochim. Cosmochim. Acta 2006 70, 2063-2072. (14) Radke, J.; Bechtel, A.; Gaupp, R.; Püttmann, W.; Schwark, L.; Sachse D.; Gleixner, G. Geochim. Cosmochim. Acta 2005 69, 5517-5530. Acknowledgements Projects CGL2012-38655-C04-01 and CGL2008-04296 and fellowship BES-2013-062573 given by the Spanish Ministry for Economy and Competitiveness to N.T.J.M. Dr. J.M. R. is the recipient of a fellowship from the JAE-Doc subprogram financed by the CSIC and the European Social Fund.

Complexity and interdisciplinary approaches to environmental research

NASA Astrophysics Data System (ADS)

Kammen, Daniel M.

2013-03-01

The launch of volume 8 of Environmental Research Letters (ERL) comes at a critical time in terms of innovations and exciting areas of science, but particularly in the areas linking environmental research and action. The most recent climate change Conference of the Parties meeting (COP), in Doha in December 2012, has now come and gone. As has been dissected in the press, very little was accomplished. Some will see this as a failure, as I do, and others will reasonably enough note that this meeting, the 18th such COP was1 never intended to be a milestone moment. The current plan, in fact, is for a 'post-Kyoto' international climate agreement to be adopted only at the COP20 summit in December 2015. As we lead up to COP20, and potentially other regional or national approaches to climate protection, innovations in science, innovations in policy tools, and political commitment must come together. The science of climate change only continues to get clearer and clearer, and bleaker [1]. Later this year the IPCC will release its Fifth Assessment Report, AR5. The draft versions are out for review now. ERL has published a number of papers on climate change science, mitigation and adaptation, but one area where the world needs a particular focus is on the nexus of science and action. A summary of the Intergovernmental Panel on Climate Change's findings from the first assessment report (FAR; 1990) to the latest report is presented in figure 1. This graphic is specifically not about the scientific record alone. What is most important about this figure is the juxtaposition of the language of science and the language of ... language. Figure 1. Figure 1. A superposition of the state of climate science in three key data sets, and the dates of the first, second, third and fourth assessment reports (FAR, SAR, TAR, and AR4, respectively) plotted as vertical lines. On the right are the key statements from each of these reports, along with the conclusion of the Special Report on Renewable Energy (SRREN, completed in 2011) which found that up to an 80% decarbonization of the global economy was possible if we can enable and launch a large-scale transition to a clean energy system consistent with what a number of 'leading edge' cities, regions, and nations have already accomplished or started. Note, in particular, that as the physical climate change metrics have progressed, the words—shown on the right—have also progressed. In 1990, at the time of the FAR the strongest scientific consensus statement was that another decade of data would likely be needed to clearly observe climate change. Through the second to fourth (SAR, TAR, and AR4) reports, increasing clarity on the science of climate change translated into a consensus of overwhelming blame on human activities. The key statements from each report are not only about the growing evidence for anthropogenically driven climate change, but they have moved into the ecological and social impacts of this change. AR4 critically concluded that climate change would lead to climate injustice as the poor, globally, bear the brunt of the impacts. Despite this 'Rosetta Stone' translating science to language, we have failed to act collectively. One area where ERL can advance the overall conversation is on this science/action interface. As AR5 emerges, the climate change/climate response interface will need deep, substantive, action that responds rapidly to new ideas and opportunities. The rapid publication and open access features of ERL are particularly critical here as events a such as Hurricane Sandy, economic or political advances in climate response made by cities, regions or nations, all warrant assessment and response. This is one of many areas where ERL has been at the forefront of the conversation, through not only research letters, but also commentary-style Perspective pieces and the conversation that ERL's sister community website environmentalresearchweb can facilitate. This process of translating proposed solutions—innovations—between interest groups, has been in far too short supply recently. One promising example has been the science/action dialog between a leading climate research center and the World Bank [2]. 'The Earth system's responses to climate change appear to be non-linear', points out Potsdam Institute for Climate Impact Research (PIK) Director, John Schellnhuber. 'If we venture far beyond the 2° guardrail, towards the 4° line, the risk of crossing tipping points rises sharply. The only way to avoid this is to break the business-as-usual pattern of production and consumption'. This assessment came in a report on climate science commissioned by the World Bank. Dr Jim Yong Kim, president of the World Bank noted succinctly and critically that: '... most importantly, a 4 °C world is so different from the current one that it comes with high uncertainty and new risks that threaten our ability to anticipate and plan for future adaptation needs.' This statement warrants careful discussion. Not only is World Bank President Kim affirming the results of the PIK study, and by direct extension the IPCC (because the same authors at PIK are also central to the work of the IPCC), but he is clearly noting that while many climate analysts rightly talk about the need to not exceed a 2° temperature increase, the path the world is currently on, namely 4°-6° will be catastrophic. This may come as too soft a statement to many in the scientific community, but it opens the door to an increasingly detailed dialog between climate change science and agencies engaged in action. Where ERL and other outlets for this conversation can play a critical role is in the many dimensions of climate change and response. The story is far from one only at the global level. As http://climatehotmap.org and many other location specific assessments detail, the environmental change story is playing out in millions of critical cases. Each warrants reporting and action, as well as integration with assessments of current data gathering and 'big data' needs, and with wider socioeconomic questions of effective political, and policy response. Through that, dialog papers in ERL will be critically important to advancing not only climate science, but the interactive dialog between knowledge and action. References [1] Hansen J, Sato M and Ruedy R 2012 Perception of climate change Proc. Natl Acad. Sci. USA 109 E2415-23 [2] Potsdam Institute for Climate Impact 2013 Turn Down the Heat: Why a 4 °C Warmer World Must be Avoided (Washington, DC: The World Bank) 1 The Kyoto Protocol was adopted on 11 December 1997 in Kyoto, Japan, and entered into force on 16 February 2005. As of September 2011, 191 states have signed and ratified the protocol. The United States signed but did not ratify the Protocol and Canada withdrew from it in 2011.

40 yr phase-out for conventional coal? If only!

NASA Astrophysics Data System (ADS)

Socolow, Robert

2012-03-01

Myhrvold and Caldeira worked out the climate consequences of various ways in which the world's current fleet of coal power plants could evolve into something different [1]. They imagined one-fortieth of the world's coal plants being closed down each year for 40 years. Two limiting cases are (1) nothing is built to take the place of this power, because efficiency gains have made them unnecessary, and (2) coal plants exactly like those now running take their place. Since coal power is the most carbon-intensive form of power, all other options fall between these limits. They looked at six single-technology alternatives: taking over from coal as we know it are coal with carbon dioxide capture and storage, natural gas, nuclear power and three forms of intermittent renewables (presented as baseload options). Moreover, whatever the alternative, it remains in place unchanged from year 40 through year 100. Results are presented as 100 yr trajectories for the increment in the average global surface temperature due only to this power production. For the coal-for-coal scenario, the surface temperature increase is about 0.13 °C in 40 yr and 0.31 °C in 100 yr. For the efficiency-for-coal scenario, the rise is 0.07 °C in 40 yr and 0.06 °C in 100 yr. Clearly, temperature rise is approximately proportional to emissions and these are self-consistent answers. For example, after 40 yr efficiency-for-coal has brought approximately half the temperature rise of coal-for-coal, and there have been exactly half the emissions. The efficiency-for-coal trajectory falls ever so slightly between years 40 and 100, because once CO2 enters the atmosphere it lingers. As for the absolute magnitude of the coal-to-coal trajectory, today's global coal power production (8300 TWh in 2008) is almost exactly what would be produced from one thousand one-gigawatt coal plants running flat out (8760 TWh), which is the coal power production assumed by Myhrvold and Caldeira. From table S1 of their paper, each GW-year of coal power production is accompanied by 6.59 Mt of CO2 emissions. Thus, a century of this coal will emit 659 billion tons of CO2. A rule of thumb recently promoted associates each trillion tons of carbon emissions (each 3.7 trillion tons of CO2 emissions) with a long-term temperature rise whose fifth and 95th per cent confidence intervals are 1.0 and 2.1 °C [2]. With this rule of thumb, the long-term temperature rise should fall between 0.18 and 0.38 °C, so the estimated rise of 0.31 °C agrees with the rule of thumb. Much of the paper is about estimates of the emissions for the alternatives to coal and efficiency. Emissions are estimated for building the physical stock as well as running it. The authors cite a high and a low value for each alternative, and the lower limits, with one exception, are close to what most analysis assumes. (The exception is natural gas, whose lower limit is 60% of the value for coal, even though values of 50% or lower are widely claimed.) The high limits are unorthodox and are already creating consternation. The high limit for hydropower reflects large emissions of methane from the lakes that form behind dams. In the cases of nuclear power, solar electric power, solar thermal power and wind power, the high limits can be attributed to emissions during construction. One suspects that these high values are straw men, avoidable with care. It is illuminating to compare the Myhrvold-Caldeira partial emissions scenarios with the two full blown scenarios of the International Energy Agency (IEA)—the Current Policy Scenario and the 450 Scenario, presented in World Energy Outlook 2010 [3]. Both IEA scenarios go only to 2035. In the Current Policies Scenario, coal emissions approximately double by 2035 (to 16 500 TWh) Myhrvold and Caldeira actually do not tell us that this is where global coal power is heading, in the absence of new policies and priorities. As for the IEA's 450 Scenario, it provides insight into the 40 yr phase-out for global coal power chosen by Myhrvold and Caldeira as their base case. In the 450 Scenario, global coal power falls to 5600 TWh in 2035, down one third from its 2008 value. By contrast, the pace for coal phase-out explored in the Myhrvold and Caldeira paper is about twice as fast: if their 40 yr phase-out had started in 2008, by 2035—27 yr later—global coal production would have fallen by about two thirds. I think one can view the 450 Scenario as capturing the IEA's judgment about the fastest achievable decarbonization of the world energy system. It is sobering to realize that allowing 40 yr for the closing out of world coal power production, which might strike some readers as relaxed, is actually so intense as to stretch credibility. The IEA 450 Scenario also sheds light on the small fraction of the potential change in the future of the global energy system that the Myhrvold-Caldeira paper captures. The 2700 TWh reduction in coal power production between 2008 and 2035 in the 450 Scenario is smaller in magnitude than the increases in wind power (3900 TWh), nuclear power (3700 TWh), and hydropower (2800 TWh) in the same interval. Myhrvold and Caldeira present a textbook exercise, not to be confused with an exploration of the full range of possible futures. I would not recommend this paper for its insight into energy systems. Rather, I would recommend it, strongly, as one of the rare papers that adequately confronts both of the sources of inertia that characterize our world: the inertia of the climate system epitomized by the durability of atmospheric CO2 and the inertia of the energy system epitomized by the durability of our capital stock. Confronting this inertia can lead us to despair that what we can change for the better each year matters so little. Or it can inspire us, because what we do each year that points in the wrong direction will take so long to undo. References [1] Myhrvold N P and Caldeira K 2012 Greenhouse gases, climate change and the transition from coal to low-carbon electricity Environ. Res. Lett. 7 014019 [2] Matthews H D, Gillett N P, Stott P A and Zickfeld K 2009 Nature 459 829 [3] IEA 2010 World Energy Outlook 2010 (Paris: IEA)

PREFACE: The IARU International Scientific Congress on Climate Change: Global Risks, Challenges and Decisions (10-12 March, Copenhagen, Denmark)

NASA Astrophysics Data System (ADS)

2009-01-01

In an attempt to make the main results from the Congress on Climate Change: Global Risk, Challenges and Decisions available to the public as early as possible, the steering committee decided to publish all talks and posters presented at the Congress in this unique collection of abstracts, in time for the conference Further to the abstract collection the Congress will publish two more products in the near future as described in the following; a synthesis report with the main conclusions, and a book aimed at an academic audience 1 Two Products from the Congress Two products are being produced based on the presentations and discussions at the Congress The first product will be a synthesis report of the main conclusions from the Congress The synthesis report will be ready in June 2009 The synthesis has the purpose of explaining the current state of understanding man-made climate change and what we can do about it to the non-scientist, ie politicians, media and interested citizens The synthesis will build on the messages presented to the Danish Prime Minister, Mr Anders Fogh Rasmussen, host of the COP15, at the closing session of the Congress These six messages were drafted by the Writing Team (see below) based on input from the session chairs and a reading of the 1600+ abstracts submitted to the Congress The second product is a book aimed at an academic audience The book will include more detailed scientific results from all of the sessions and will be published by Cambridge University Press in 2010 It will be an extension and elaboration of the synthesis report Who's writing the Synthesis Report and the Book? A Writing Team consisting of 12 internationally respected scientists from all continents is responsible for developing both products When the synthesis report has been drafted by the Writing Team, it will be discussed in the Scientific Steering Committee of the Congress and reviewed by the Earth System Science Partnership (ESSP) and a group of experts identified by the IARU universities In keeping with normal scientific practice, a procedure for producing the synthesis report that has been adopted optimises the chances of arriving at a product that will receive a broad backing from the scientific community as being a message that can be sent to the non-scientific community and that explains current understanding in climate change science The Writing Team will also be responsible for writing the book Members of the Writing Team (in alphabetical order) Professor Joe Alcamo, University of Stellenbosch Dr Terry Barker, Cambridge University Professor Daniel Kammen, University of California - Berkeley Professor Rik Leemans, Environmental Systems Analysis Group, Wageningen University Professor Diana Liverman, Oxford University Professor Mohan Munasinghe, Chairman, Munasinghe Institute for Development (MIND) Dr Balgis Osman-Elasha, Higher Council for Environment and Natural Resources (HCENR), Sudan Professor Katherine Richardson, University of Copenhagen Professor John Schellnhuber, Potsdam Institute for Climate Impact Research and visiting professor at the University of Oxford Professor Will Steffen, Australian National University Professor Lord Nicholas Stern, London School of Economics and Political Science (LSE) Professor Ole Wæver, University of Copenhagen 2 Key Messages from the Congress Key Message 1: Climatic Trends Recent observations confirm that, given high rates of observed emissions, the worst-case IPCC scenario trajectories (or even worse) are being realized For many key parameters, the climate system is already moving beyond the patterns of natural variability within which our society and economy have developed and thrived These parameters include global mean surface temperature, sea-level rise, ocean and ice sheet dynamics, ocean acidification, and extreme climatic events There is a significant risk that many of the trends will accelerate, leading to an increasing risk of abrupt or irreversible climatic shifts Key Message 2: Social disruption The research community is providing much more information to support discussions on 'dangerous climate change' Recent observations show that societies are highly vulnerable to even modest levels of climate change, with poor nations and communities particularly at risk Temperature rises above 2°C will be very difficult for contemporary societies to cope with, and will increase the level of climate disruption through the rest of the century Key Message 3: Long-Term Strategy Rapid, sustained, and effective mitigation based on coordinated global and regional action is required to avoid 'dangerous climate change' regardless of how it is defined Weaker targets for 2020 increase the risk of crossing tipping points and make the task of meeting 2050 targets more difficult Delay in initiating effective mitigation actions increases significantly the long-term social and economic costs of both adaptation and mitigation Key Message 4: Equity Dimensions Climate change is having, and will have, strongly differential effects on people within and between countries and regions, on this generation and future generations, and on human societies and the natural world An effective, well-funded adaptation safety net is required for those people least capable of coping with climate change impacts, and a common but differentiated mitigation strategy is needed to protect the poor and most vulnerable Key Message 5: Inaction is Inexcusable There is no excuse for inaction We already have many tools and approaches - economic, technological, behavioral, management - to deal effectively with the climate change challenge But they must be vigorously and widely implemented to achieve the societal transformation required to decarbonize economies A wide range of benefits will flow from a concerted effort to alter our energy economy now, including sustainable energy job growth, reductions in the health and economic costs of climate change, and the restoration of ecosystems and revitalization of ecosystem services Key Message 6: Meeting the Challenge To achieve the societal transformation required to meet the climate change challenge, we must overcome a number of significant constraints and seize critical opportunities These include reducing inertia in social and economic systems; building on a growing public desire for governments to act on climate change; removing implicit and explicit subsidies; reducing the influence of vested interests that increase emissions and reduce resilience; enabling the shifts from ineffective governance and weak institutions to innovative leadership in government, the private sector and civil society; and engaging society in the transition to norms and practices that foster sustainability The editors of the volume are all the session chairs: Professor Agus Sari Dr Aled Jones Science Manager Anders Viksø-Nielsen Dr Andreas Barkman Professor Anette Reenberg Professor Ann Henderson-Sellers Professor Anthony J McMichael Dr Anthony Patt Dr Bette Otto-Bliesner Dr Cameron Hepburn Dr Carlos Nobre Dr Carol Turley Dr Chris Hope Professor Chris Turney Professor Claus Felby Professor Coleen Vogel Professor Dale Jamieson Professor Daniel M Kammen Senior Scientist Detlef F Sprinz Professor Diana Ürge-Vorsatz Professor Dorthe Dahl-Jensen PhD Fatima Denton Director Generel Frances Seymour Dr Frank Jotzo Professor Harold Mooney Director Henrik Bindslev Mr Jamie Pittock Professor Jacquie Burgess Dr James E Hansen Professor Jiahua Pan Dr Jill Jäger Professor Jim Skea Professor Johan Rockström Dr John Christensen Professor John Mitchell Professor John R Porter Professor Joyeeta Gupta Professor Jørgen E Olesen Professor Karen O'Brien Dr Kazuhiko Takeuchi Dr Katrine Krogh Andersen Professor Keith Paustian Professor Ken Caldeira Professor Kevin Anderson Dr Koko Warner Professor Konrad Steffen Professor Liping Zhou Professor Louise Fresco Professor Maria Carmen Lemos Professor Mark Ashton Dr Mark Stafford-Smith Dr Martin Claussen Dr Martin Visbeck Professor Mary Scholes Professor Masahide Kimoto Professor Matthew England Dr Maxwell Boykoff Dr Michael Raupach Professor Nathan Bindoff Professor Nicolas Gruber Professor Niels Elers Koch Professor Ole John Nielsen Professor Ole Wæver Professor Oran Young Dr Pamela Matson Dr Paul Baer Professor Paul Leadley Dr Pep Canadell Professor Pete Smith Professor Peter Gregory Professor Pier Vellinga Dr Rik Leemans Dr Roberto Bertollini Professor Roberto S Rodriguez Professor Scott Denning Dr Sivan Kartha Dr Thomas Downing Dr Tariq Banuri Professor Thomas Heyd Professor Tim Lenton Professor Timmons Roberts Professor Torkil Jønch Clausen Professor Warwick McKibbin Professor Wim C Turkenburg