Sample records for dioxide methane ethane

  1. Homogeneous nucleation in supersaturated vapors of methane, ethane, and carbon dioxide predicted by brute force molecular dynamics.

    PubMed

    Horsch, Martin; Vrabec, Jadran; Bernreuther, Martin; Grottel, Sebastian; Reina, Guido; Wix, Andrea; Schaber, Karlheinz; Hasse, Hans

    2008-04-28

    Molecular dynamics (MD) simulation is applied to the condensation process of supersaturated vapors of methane, ethane, and carbon dioxide. Simulations of systems with up to a 10(6) particles were conducted with a massively parallel MD program. This leads to reliable statistics and makes nucleation rates down to the order of 10(30) m(-3) s(-1) accessible to the direct simulation approach. Simulation results are compared to the classical nucleation theory (CNT) as well as the modification of Laaksonen, Ford, and Kulmala (LFK) which introduces a size dependence of the specific surface energy. CNT describes the nucleation of ethane and carbon dioxide excellently over the entire studied temperature range, whereas LFK provides a better approach to methane at low temperatures.

  2. Natural gas geochemistry of sediments drilled on the 2005 Gulf of Mexico JIP cruise

    USGS Publications Warehouse

    Lorenson, T.D.; Claypool, G.E.; Dougherty, J.A.

    2008-01-01

    In April and May 2005, cores were acquired and sub-sampled for gases in lease blocks Atwater Valley 13 and 14 and Keathley Canyon 151 during deep subseafloor drilling conducted as part of the JIP study of gas hydrates in the northern Gulf of Mexico. Sample types included sediment headspace gas, free gas derived from sediment gas exsolution, and gas exsolution from controlled degassing of pressurized cores. The gases measured both onboard and in shore-based labs were nitrogen, oxygen, hydrogen sulfide, carbon dioxide, and the hydrocarbons methane through hexane. The presence of seafloor mounds, seismic anomalies, a shallow sulfate-methane interface, and similar gas compositions and isotopic compositions near the seafloor and at depth suggest an upward flux of methane at both sites. Sediment gases at the Atwater Valley sites, where seafloor mounds and adjacent sediments were cored, strongly suggest a microbial source of methane, with very little thermogenic gas input. Sediment gas from all cores contained from about 96 to 99.9% methane, with the balance composed primarily of carbon dioxide. Methane to ethane ratios were greater than 1000, and often over 10,000. Gases from cores at Keathley Canyon were similar to those at Atwater Valley, however, deeper cores from Keathley Canyon contained more ethane, propane, and butane suggesting mixing with minor concentrations thermogenic gas. The isotopic composition of methane, ethane, and carbon dioxide were measured, and ??13C values range from -84.3 to -71.5???, -65.2 to -46.8???, and -23.5 to -3.0???, respectively, all consistent with microbial gas sources, early diagenesis of organic matter and perhaps biodegradation of petroleum. The presence of deep microbial gas at these sites here and elsewhere highlights a potentially significant, predominantly microbial gas source in the northern Gulf of Mexico.

  3. High rates of anaerobic oxidation of methane, ethane and propane coupled to thiosulphate reduction.

    PubMed

    Suarez-Zuluaga, Diego A; Weijma, Jan; Timmers, Peer H A; Buisman, Cees J N

    2015-03-01

    Anaerobic methane oxidation coupled to sulphate reduction and the use of ethane and propane as electron donors by sulphate-reducing bacteria represent new opportunities for the treatment of streams contaminated with sulphur oxyanions. However, growth of microbial sulphate-reducing populations with methane, propane or butane is extremely slow, which hampers research and development of bioprocesses based on these conversions. Thermodynamic calculations indicate that the growth rate with possible alternative terminal electron acceptors such as thiosulphate and elemental sulphur may be higher, which would facilitate future research. Here, we investigate the use of these electron acceptors for oxidation of methane, ethane and propane, with marine sediment as inoculum. Mixed marine sediments originating from Aarhus Bay (Denmark) and Eckernförde Bay (Germany) were cultivated anaerobically at a pH between 7.2 and 7.8 and a temperature of 15 °C in the presence of methane, ethane and propane and various sulphur electron acceptors. The sulphide production rates in the conditions with methane, ethane and propane with sulphate were respectively 2.3, 2.2 and 1.8 μmol S L(-1) day(-1). For sulphur, no reduction was demonstrated. For thiosulphate, the sulphide production rates were up to 50 times higher compared to those of sulphate, with 86.2, 90.7 and 108.1 μmol S L(-1) day(-1) for methane, ethane and propane respectively. This sulphide production was partly due to disproportionation, 50 % for ethane but only 7 and 14 % for methane and propane respectively. The oxidation of the alkanes in the presence of thiosulphate was confirmed by carbon dioxide production. This is, to our knowledge, the first report of thiosulphate use as electron acceptor with ethane and propane as electron donors. Additionally, these results indicate that thiosulphate is a promising electron acceptor to increase start-up rates for sulphate-reducing bioprocesses coupled to short-chain alkane oxidation.

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

    Warren, B.K.; Campbell, K.D.

    Methane oxidative coupling studies were carried out in an atmospheric quartz reactor at temperatures between 700 and 800/degree/C. New catalysts prepared and studied included doped alkaline earth catalysts, lanthanide oxides, and proprietary catalysts. Neodymium oxide, Nd/sub 2/O/sub 3/, was found to be as active and selective as samarium oxide, Sm/sub 2/O/sub 3/, in contrast to literature reports. Proprietary Union Carbide catalysts (UCC-S:1) showed initial methane conversions and C/sub 2/ selectivities comparable to literature catalysts. Atypically low carbon dioxide to carbon monoxide ratios (typically ten times lower than those seen in the literature or other catalysts tested) and high ethylene tomore » ethane ratios (3 to 6 compared to typical literature ratios below 1) were obtained. These results are interesting because ethylene is more valuable than ethane and carbon monoxide is more valuable than carbon dioxide. With these UCC-S:1 catalysts, rapid deactivation was coupled with an observed shift in product ratios toward those more typical in the literature. Initial cases for process conceptualization studies were selected. The Comparison Case will consist of the conversion sequence from methane to synthesis gas to methanol to olefins to liquid hydrocarbon fuels. Case 1 will consist of the conversion of methane to ethylene and ethane. Case 2 will be the direct conversion of methane to C/sub 2/'s followed by conversion to liquid hydrocarbon fuels. 7 figs., 18 tabs.« less

  5. 33 CFR 160.204 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ....7: (i) Ammonia, anhydrous; (ii) Chlorine; (iii) Ethane; (iv) Ethylene oxide; (v) Methane (LNG); (vi) Methyl bromide; (vii) Sulfur dioxide; and (viii) Vinyl chloride. Charterer means the person or...

  6. Estimates of methane and ethane emissions from the Texas Barnett Shale

    NASA Astrophysics Data System (ADS)

    Karion, A.; Sweeney, C.; Yacovitch, T.; Petron, G.; Wolter, S.; Conley, S. A.; Hardesty, R. M.; Brewer, A.; Kofler, J.; Newberger, T.; Herndon, S.; Miller, B. R.; Montzka, S. A.; Rella, C.; Crosson, E.; Tsai, T.; Tans, P. P.

    2013-12-01

    The recent development of horizontal drilling technology by the oil and gas industry has dramatically increased onshore U.S. natural gas and oil production in the last several years. This production boom has led to wide-spread interest from the policy and scientific communities in quantifying the climate impact of the use of natural gas as a replacement for coal. Because the primary component of natural gas is methane, a powerful greenhouse gas, natural gas leakage into the atmosphere affects its climate impact. Several recent scientific field studies have focused on using atmospheric measurements to estimate this leakage in different producing basins. Methane can be measured precisely with commercial analyzers, and deployment of such analyzers on aircraft, coupled with meteorological measurements, can allow scientists to estimate emissions from regions of concentrated production. Ethane and other light hydrocarbons, also components of raw gas, can be used as tracers for differentiating natural gas emissions from those of other methane sources, such as agriculture or landfills, which do not contain any non-methane hydrocarbons such as ethane. Here we present results from one such field campaign in the Barnett Shale near Fort Worth, Texas, in March 2013. Several 4-hour flights were conducted over the natural gas and oil production region with a small single-engine aircraft instrumented with analyzers for measuring ambient methane, carbon monoxide, carbon dioxide, and ethane at high frequencies (0.3-1Hz). The aircraft also measured horizontal winds, temperature, humidity, and pressure, and collected whole air samples in flasks analyzed later for several light hydrocarbons. In addition to the aircraft, a ground-based High-Resolution Doppler Lidar was deployed in the basin to measure profiles of horizontal winds and estimate the boundary layer height 24 hours a day over the campaign period. The aircraft and lidar measurements are used together to estimate methane and ethane emissions in the region. Flight track colored by methane (CH4, left) and ethane (C2H6, right) mole fraction. A three-hour back trajectory (red line) constructed from lidar wind measurements passes over the Barnett natural gas well locations (gray points) prior to reaching the location on the flight path indicated by the red star.

  7. Demonstration of an ethane spectrometer for methane source identification.

    PubMed

    Yacovitch, Tara I; Herndon, Scott C; Roscioli, Joseph R; Floerchinger, Cody; McGovern, Ryan M; Agnese, Michael; Pétron, Gabrielle; Kofler, Jonathan; Sweeney, Colm; Karion, Anna; Conley, Stephen A; Kort, Eric A; Nähle, Lars; Fischer, Marc; Hildebrandt, Lars; Koeth, Johannes; McManus, J Barry; Nelson, David D; Zahniser, Mark S; Kolb, Charles E

    2014-07-15

    Methane is an important greenhouse gas and tropospheric ozone precursor. Simultaneous observation of ethane with methane can help identify specific methane source types. Aerodyne Ethane-Mini spectrometers, employing recently available mid-infrared distributed feedback tunable diode lasers (DFB-TDL), provide 1 s ethane measurements with sub-ppb precision. In this work, an Ethane-Mini spectrometer has been integrated into two mobile sampling platforms, a ground vehicle and a small airplane, and used to measure ethane/methane enhancement ratios downwind of methane sources. Methane emissions with precisely known sources are shown to have ethane/methane enhancement ratios that differ greatly depending on the source type. Large differences between biogenic and thermogenic sources are observed. Variation within thermogenic sources are detected and tabulated. Methane emitters are classified by their expected ethane content. Categories include the following: biogenic (<0.2%), dry gas (1-6%), wet gas (>6%), pipeline grade natural gas (<15%), and processed natural gas liquids (>30%). Regional scale observations in the Dallas/Fort Worth area of Texas show two distinct ethane/methane enhancement ratios bridged by a transitional region. These results demonstrate the usefulness of continuous and fast ethane measurements in experimental studies of methane emissions, particularly in the oil and natural gas sector.

  8. Evaluation of dopants in hydrogen to reduce hydrogen permeation in candidate Stirling engine heater head tube alloys at 760 deg and 820 deg

    NASA Technical Reports Server (NTRS)

    Misencik, J. A.

    1982-01-01

    Alloy tubes filled with hydrogen doped with various amounts of carbon monoxide, carbon dioxide, ethane, ethylene, methane, ammonia, or water were heated in a diesel fuel-fired Stirling engine simulator materials test rig for 100 hours at 21 MPa and 760 or 820 C to determine the effectiveness of the dopants in reducing hydrogen permeation through the hot tube walls. Ultra high purity (UHP) hydrogen was used for comparison. The tube alloys were N-155, A-286, Incoloy 800, Nitronic 40, 19-9DL, 316 stainless steel, Inconel 718, and HS-188. Carbon dioxide and carbon monoxide in the concentration range 0.2 to 5 vol % were most effective in reducing hydrogen permeation through the hot tube walls for all alloys. Ethane, ethylene, methane, ammonia, and water at the concentrations investigated were not effective in reducing the permeation below that achieved with UHP hydrogen. One series of tests were conducted with UHP hydrogen in carburized tubes. Carburization of the tubes prior to exposure reduced permeation to values similar to those for carbon monoxide; however, carbon dioxide was the most effective dopant.

  9. Cloudy with a Chance of Ice: The Stratification of Titan's Vernal Ponds and Formation of Ethane Ice

    NASA Astrophysics Data System (ADS)

    Soderblom, J. M.; Steckloff, J. K.

    2017-12-01

    Cassini ISS observations revealed regions on Saturn's moon Titan that become significantly darker (lower albedo) following storm events [1]. These regions are observed to be topographically low [2], indicating that liquid (predominantly methane-ethane-nitrogen) is pooling on Titan after these storm events. These dark ponds, however, are then observed to significantly brighten (higher albedo relative to pre-storm albedo), before fading to their pre-storm albedos [2-3]. We interpret these data to indicate ethane ice formation, which cools from evaporation of methane. The formation of ethane ices results from a unique sequence of thermophysical and thermochemical phenomena. Initially, the methane in the mixture evaporates, cooling the pond. Nitrogen, dissolved primarily in the methane, exsolves, further cooling the liquid. However, because nitrogen is significantly more soluble in cooler methane-hydrocarbon mixtures, relatively more methane than nitrogen leaves the fluid, increasing the relative fraction of nitrogen. This increased nitrogen fraction increases the density of the liquid, as nitrogen is significantly denser than methane or ethane (pure ethane's density is intermediate to that of methane and nitrogen). At around 85 K the mixture is as dense as pure liquid ethane. Thus, further evaporative methane loss and cooling at the pond's surface leads to a chemical stratification, with an increasingly ethane rich epilimnion (surface layer) overlying a methane rich hypolimnion (subsurface layer). Further evaporation of methane from the ethane-rich epilimnion drives its temperature and composition toward the methane-ethane-nitrogen liquidus curve, causing pure ethane ice to precipitate out of solution and settle to the bottom of the pool. This settling would obscure the ethane ice from Cassini VIMS and ISS, which would instead continue to appear as a dark pond on the surface. As the ethane precipitates out completely, a binary methane-nitrogen liquid mixture remains. Eventually, this residual liquid evaporates away, exposing the submerged ethane ice, which Cassini VIMS and ISS would observe as a dramatic brightening of the surface, consistent with observations. [1] Turtle et al. 2009, GRL; 2011, Science; [2] Soderblom et al. 2014, DPS; [3] Barnes et al. 2013 Planet. Sci

  10. Pond Hockey on Whitmore Lacus: the Formation of Ponds and Ethane Ice Deposits Following Storm Events on Titan

    NASA Astrophysics Data System (ADS)

    Steckloff, Jordan; Soderblom, Jason M.

    2017-10-01

    Cassini ISS observations reveled regions, later identified as topographic low spots (Soderblom et al. 2014, DPS) on Saturn’s moon Titan become significantly darker (lower albedo) following storm events (Turtle et al. 2009, GRL; 2011, Science), suggesting pools of liquid hydrocarbon mixtures (predominantly methane-ethane-nitrogen). However, these dark ponds then significantly brighten (higher albedo relative to pre-storm albedo), before fading to their pre-storm albedos (Barnes et al. 2013 Planet. Sci; Soderblom et al. 2014, DPS). We interpret these data to be the result of ethane ice formation, which cools from evaporation of methane. The formation of ethane ices results from a unique sequence of thermophysical processes. Initially, the methane in the ternary mixture evaporates, cooling the pond. Nitrogen, dissolved primarily in the methane, exsolves, further cooling the liquid. However, because nitrogen is significantly more soluble in cooler methane-hydrocarbon mixtures, the relative concentration of nitrogen in the solution increases as it cools. This increased nitrogen fraction increases the density of the pond, as nitrogen is significantly more dense thane methane or ethane (pure ethane’s density is intermediate to that of methane and nitrogen). At around ~85 K the mixture is as dense as pure liquid ethane. Thus, further evaporative methane loss and cooling at the pond’s surface leads to a chemical stratification, with an increasingly ethane rich epilimnion (surface layer) overlying a methane rich hypolimnion (subsurface layer). Further evaporation of methane from the ethane-rich epilimnion drives its temperature and composition toward the methane-ethane-nitrogen liquidus curve, causing pure ethane ice to precipitate out of solution and settle to the bottom of the pool. This settling would obscure the ethane ice from Cassini VIMS and ISS, which would instead continue to appear as a dark pond on the surface. As the ethane precipitates out completely, a binary methane-nitrogen liquid mixture remains. Eventually, this residual liquid evaporates away, exposing the submerged ethane ice, which Cassini VIMS and ISS would observe as a dramatic brightening of the surface, consistent with observations.

  11. Raman studies of methane-ethane hydrate metastability.

    PubMed

    Ohno, Hiroshi; Strobel, Timothy A; Dec, Steven F; Sloan, E Dendy; Koh, Carolyn A

    2009-03-05

    The interconversion of methane-ethane hydrate from metastable to stable structures was studied using Raman spectroscopy. sI and sII hydrates were synthesized from methane-ethane gas mixtures of 65% or 93% methane in ethane and water, both with and without the kinetic hydrate inhibitor, poly(N-vinylcaprolactam). The observed faster structural conversion rate in the higher methane concentration atmosphere can be explained in terms of the differences in driving force (difference in chemical potential of water in sI and sII hydrates) and kinetics (mass transfer of gas and water rearrangement). The kinetic hydrate inhibitor increased the conversion rate at 65% methane in ethane (sI is thermodynamically stable) but retards the rate at 93% methane in ethane (sII is thermodynamically stable), implying there is a complex interaction between the polymer, water, and hydrate guests at crystal surfaces.

  12. An analytical solubility model for nitrogen-methane-ethane ternary mixtures

    NASA Astrophysics Data System (ADS)

    Hartwig, Jason; Meyerhofer, Peter; Lorenz, Ralph; Lemmon, Eric

    2018-01-01

    Saturn's moon Titan has surface liquids of liquid hydrocarbons and a thick, cold, nitrogen atmosphere, and is a target for future exploration. Critical to the design and operation of vehicles for this environment is knowledge of the amount of dissolved nitrogen gas within the cryogenic liquid methane and ethane seas. This paper rigorously reviews experimental data on the vapor-liquid equilibrium of nitrogen/methane/ethane mixtures, noting the possibility for split liquid phases, and presents simple analytical models for conveniently predicting solubility of nitrogen in pure liquid ethane, pure liquid methane, and a mixture of liquid ethane and methane. Model coefficients are fit to three temperature ranges near the critical point, intermediate range, and near the freezing point to permit accurate predictions across the full range of thermodynamic conditions. The models are validated against the consolidated database of 2356 experimental data points, with mean absolute error between data and model less than 8% for both binary nitrogen/methane and nitrogen/ethane systems, and less than 17% for the ternary nitrogen/methane/ethane system. The model can be used to predict the mole fractions of ethane, methane, and nitrogen as a function of location within the Titan seas.

  13. Method of detecting leakage from geologic formations used to sequester CO.sub.2

    DOEpatents

    White, Curt [Pittsburgh, PA; Wells, Arthur [Bridgeville, PA; Diehl, J Rodney [Pittsburgh, PA; Strazisar, Brian [Venetia, PA

    2010-04-27

    The invention provides methods for the measurement of carbon dioxide leakage from sequestration reservoirs. Tracer moieties are injected along with carbon dioxide into geological formations. Leakage is monitored by gas chromatographic analyses of absorbents. The invention also provides a process for the early leak detection of possible carbon dioxide leakage from sequestration reservoirs by measuring methane (CH.sub.4), ethane (C.sub.2H.sub.6), propane (C.sub.3H.sub.8), and/or radon (Rn) leakage rates from the reservoirs. The invention further provides a method for branding sequestered carbon dioxide using perfluorcarbon tracers (PFTs) to show ownership.

  14. Airborne Ethane Observations over the Barnett and Bakken Shale Formations: Quantification of Ethane Fluxes and Attribution of Methane Emissions

    NASA Astrophysics Data System (ADS)

    Smith, M. L.; Kort, E. A.; Karion, A.; Sweeney, C.; Peischl, J.; Ryerson, T. B.

    2014-12-01

    The largest emissions sources of methane, a potent greenhouse gas and the primary component of natural gas, are the fossil fuel sector and microbial processes that occur in agricultural settings, landfills, and wetlands. Attribution of methane to these different source sectors has proven difficult, as evidenced by persistent disagreement between the annual emissions estimated from atmospheric observations (top-down) and from inventories (bottom-up). Given the rapidly changing natural gas infrastructure in North America, and the implications of associated rapid changes in emissions of methane for climate, it is crucial we improve our ability to quantify and understand current and future methane emissions. Here, we present evidence that continuous in-situ airborne observations of ethane, which is a tracer for fossil fuel emissions, are a new and useful tool for attribution of methane emissions to specific source sectors. Additionally, with these new airborne observations we present the first tightly constrained ethane emissions estimates of oil and gas production fields using the well-known mass balance method. The ratios of ethane-to-methane (C2H6:CH4) of specific methane emissions sources were studied over regions of high oil and gas production from the Barnett, TX and Bakken, ND shale plays, using continuous (1Hz frequency) airborne ethane measurements paired with simultaneous methane measurements. Despite the complex mixture of sources in the Barnett region, the methane emissions were well-characterized by distinct C2H6:CH4 relationships indicative of a high-ethane fossil fuel source (e.g., "wet" gas), a low-ethane fossil fuel source (e.g., "dry" gas), and an ethane-free, or microbial source. The defined set of C2H6:CH4 that characterized the emissions input to the atmosphere was used in conjunction with the total ethane and methane fluxes to place bounds on the fraction of methane emissions attributable to each source. Additionally, substantial ethane fluxes from the Barnett and Bakken regions were observed (1% to 10% of estimated national ethane emissions), and emissions of these magnitudes may significantly impact regional atmospheric chemistry and air quality by influencing production of tropospheric ozone.

  15. Long-term decline of global atmospheric ethane concentrations and implications for methane.

    PubMed

    Simpson, Isobel J; Sulbaek Andersen, Mads P; Meinardi, Simone; Bruhwiler, Lori; Blake, Nicola J; Helmig, Detlev; Rowland, F Sherwood; Blake, Donald R

    2012-08-23

    After methane, ethane is the most abundant hydrocarbon in the remote atmosphere. It is a precursor to tropospheric ozone and it influences the atmosphere's oxidative capacity through its reaction with the hydroxyl radical, ethane's primary atmospheric sink. Here we present the longest continuous record of global atmospheric ethane levels. We show that global ethane emission rates decreased from 14.3 to 11.3 teragrams per year, or by 21 per cent, from 1984 to 2010. We attribute this to decreasing fugitive emissions from ethane's fossil fuel source--most probably decreased venting and flaring of natural gas in oil fields--rather than a decline in its other major sources, biofuel use and biomass burning. Ethane's major emission sources are shared with methane, and recent studies have disagreed on whether reduced fossil fuel or microbial emissions have caused methane's atmospheric growth rate to slow. Our findings suggest that reduced fugitive fossil fuel emissions account for at least 10-21 teragrams per year (30-70 per cent) of the decrease in methane's global emissions, significantly contributing to methane's slowing atmospheric growth rate since the mid-1980s.

  16. Structural changes and preferential cage occupancy of ethane hydrate and methane-ethane mixed gas hydrate under very high pressure.

    PubMed

    Hirai, Hisako; Takahara, Naoya; Kawamura, Taro; Yamamoto, Yoshitaka; Yagi, Takehiko

    2008-12-14

    High-pressure experiments of ethane hydrate and methane-ethane mixed hydrates with five compositions were performed using a diamond anvil cell in a pressure range of 0.1-2.8 GPa at room temperature. X-ray diffractometry and Raman spectroscopy showed structural changes as follows. The initial structure, structure I (sI), of ethane hydrate was retained up to 2.1 GPa without any structural change. For the mixed hydrates, sI was widely distributed throughout the region examined except for the methane-rich and lower pressure regions. For the ethane-rich and intermediate composition regions (73 mol % ethane sample and 53% sample), sI was maintained up to 2.1 GPa. With increasing methane component (34% and 30% samples), sI existed at pressures from 0.1 to about 1.0 GPa. Hexagonal structure (sH) appeared in addition to sI at 1.3 GPa for the 34% sample and at 1.1 GPa for the 30% sample. By further increasing the methane component (22% sample), structure II (sII) existed solely up to 0.3 GPa. From 0.3 to 0.6 GPa, sII and sI coexisted, and from 0.6 to 1.0 GPa only sI existed. At 1.2 GPa sH appeared, and sH and sI coexisted up to 2.1 GPa. Above 2.1 GPa, ethane hydrate and all of the mixed hydrates decomposed into ice VI and ethane fluid or methane-ethane fluid, respectively. The Raman study revealed that occupation of the small cages by ethane molecules occurred above 0.1 GPa in ethane hydrate and continued up to decomposition at 2.1 GPa, although it is thought that ethane molecules are contained only in the large cage.

  17. 40 CFR 60.614 - Test methods and procedures.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... or TOC (less methane and ethane) reduction efficiency shall be prior to the inlet of the control... TOC (minus methane and ethane), dry basis, ppm by volume. %O2d=Concentration of O2, dry basis, percent.... (ii) The emission reduction (R) of TOC (minus methane and ethane) shall be determined using the...

  18. 40 CFR 60.664 - Test methods and procedures.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... (less methane and ethane) reduction efficiency shall be prior to the inlet of the control device and... methane and ethane), dry basis, ppm by volume. %O2d=Concentration of O2, dry basis, percent by volume. (4... emission reduction (R) of TOC (minus methane and ethane) shall be determined using the following equation...

  19. Ethane's 12C/13C Ratio in Titan: Implications for Methane Replenishment

    NASA Technical Reports Server (NTRS)

    Jennings, Donald E.; Nixon, C. A.; Romani, P. N.; Bjoraker, G. L.; Sada, P. V.; Lunsford, A. W.; Boyle, R. J.; Hesman, B. E.; McCabe, G. H.

    2009-01-01

    As the .main destination of carbon in the destruction of methane in the atmosphere of Titan, ethane provides information about the carbon isotopic composition of the reservoir from which methane is replenished. If the amount of methane entering the atmosphere is presently equal to the amount converted to ethane, the 12C/13C ratio in ethane should be close to the ratio in the reservoir. We have measured the 12C/13C ratio in ethane both with Cassini CIRS(exp 1) and from the ground and find that it is very close to the telluric standard and outer planet values (89), consistent with a primordial origin for the methane reservoir. The lower 12C/13C ratio measured for methane by Huygens GCMS (82.3) can be explained if the conversion of CH4 to CH3 (and C2H6) favors 12C over 13C with a carbon kinetic isotope effect of 1.08. The time required for the atmospheric methane to reach equilibrium, i.e., for replenishment to equal destruction, is approximately 5 methane atmospheric lifetimes.

  20. Microbial Community Dynamics in Methane-Oxidizing Mesocosms from the Gulf of Mexico and U.S. Atlantic Margin

    NASA Astrophysics Data System (ADS)

    Redmond, M. C.; Sorgen, A. A.; Chan, E. W.; Kessler, J. D.

    2016-12-01

    Microbial methane oxidation at natural gas seeps plays an important role in reducing the amount of this greenhouse gas that reaches the atmosphere, but questions remain about the factors that control methane oxidation rates and organisms responsible. We collected water samples from methane seeps on the U.S. Atlantic Margin (Hudson Canyon) and the Gulf of Mexico and tracked aerobic methane oxidation with high resolution measurements of methane, carbon dioxide, and oxygen concentrations, stable isotopic changes in methane and carbon dioxide, trace metals and nutrients in ten replicate mesocosms from each site. At several time points, we collected DNA for 16S rRNA gene and metagenomic sequencing. Hudson Canyon seep mesocosm communities were dominated by methanotrophs from the family Methylococcaceae (>75% of 16S rRNA gene sequences in all samples). Methylococcaceae were also present in the Gulf of Mexico mesocosms, but were much less abundant (<50% of 16S rRNA gene sequences) and methane was consumed less rapidly than in the Hudson Canyon mesocosms. The Hudson Canyon seeps emit only methane, whereas the Gulf of Mexico seeps also emit ethane, propane, and other hydrocarbons. Consistent with this differing geochemistry, hydrocarbon degraders such as Colwellia and Cycloclasticus were also abundant in the Gulf of Mexico mesocosms, as were genes for the oxidation of longer chain alkanes and aromatic compounds.

  1. Development of a Flight Instrument for in situ Measurements of Ethane and Methane

    NASA Astrophysics Data System (ADS)

    Wilkerson, J. P.; Sayres, D. S.; Anderson, J. G.

    2015-12-01

    Methane emissions data for natural gas and oil fields have high uncertainty. Better quantifying these emissions is crucial to establish an accurate methane budget for the United States. One obstacle is that these emissions often occur in areas near livestock facilities where biogenic methane abounds. Measuring ethane, which has no biogenic source, along with methane can tease these sources apart. However, ethane is typically measured by taking whole-air samples. This tactic has lower spatial resolution than making in situ measurements and requires the measurer to anticipate the location of emission plumes. This leaves unexpected plumes uncharacterized. Using Re-injection Mirror Integrated Cavity Output Spectroscopy (RIM-ICOS), we can measure both methane and ethane in flight, allowing us to establish more accurate fugitive emissions data that can more readily distinguish between different sources of this greenhouse gas.

  2. Active Thermochemical Tables: Sequential Bond Dissociation Enthalpies of Methane, Ethane, and Methanol and the Related Thermochemistry

    DOE PAGES

    Ruscic, Branko

    2015-03-31

    Active Thermochemical Tables (ATcT) thermochemistry for the sequential bond dissociations of methane, ethane, and methanol systems were obtained by analyzing and solving a very large thermochemical network (TN). Values for all possible C–H, C–C, C–O, and O–H bond dissociation enthalpies at 298.15 K (BDE 298) and bond dissociation energies at 0 K (D 0) are presented. The corresponding ATcT standard gas-phase enthalpies of formation of the resulting CH n, n = 4–0 species (methane, methyl, methylene, methylidyne, and carbon atom), C 2H n, n = 6–0 species (ethane, ethyl, ethylene, ethylidene, vinyl, ethylidyne, acetylene, vinylidene, ethynyl, and ethynylene), and COHmore » n, n = 4–0 species (methanol, hydroxymethyl, methoxy, formaldehyde, hydroxymethylene, formyl, isoformyl, and carbon monoxide) are also presented. The ATcT thermochemistry of carbon dioxide, water, hydroxyl, and carbon, oxygen, and hydrogen atoms is also included, together with the sequential BDEs of CO 2 and H 2O. The provenances of the ATcT enthalpies of formation, which are quite distributed and involve a large number of relevant determinations, are analyzed by variance decomposition and discussed in terms of principal contributions. The underlying reasons for periodic appearances of remarkably low and/or unusually high BDEs, alternating along the dissociation sequences, are analyzed and quantitatively rationalized. The present ATcT results are the most accurate thermochemical values currently available for these species.« less

  3. 40 CFR Table B-3 to Subpart B of... - Interferent Test Concentration, 1 Parts per Million

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Nitric oxide Carbon dioxide Ethylene Ozone Mxy-lene Water vapor Carbon monoxide Methane Ethane... 4 0.14 750 3 20,000 50 SO2 Gas chromatography 0.1 4 0.14 750 3 20,000 50 SO2 Spectrophotometric-wet... 0.5 3 20,000 SO2 Conductivity 0.2 0.1 4 0.14 0.5 750 SO2 Spectrophotometric-gas phase, including...

  4. NMR study of methane + ethane structure I hydrate decomposition.

    PubMed

    Dec, Steven F; Bowler, Kristen E; Stadterman, Laura L; Koh, Carolyn A; Sloan, E Dendy

    2007-05-24

    The thermally activated decomposition of methane + ethane structure I hydrate was studied with use of 13C magic-angle spinning (MAS) NMR as a function of composition and temperature. The observed higher decomposition rate of large sI cages initially filled with ethane gas can be described in terms of a model where a distribution of sI unit cells exists such that a particular unit cell contains zero, one, or two methane molecules in the unit cell; this distribution of unit cells is combined to form the observed equilibrium composition. In this model, unit cells with zero methane molecules are the least stable and decompose more rapidly than those populated with one or two methane molecules leading to the observed overall faster decomposition rate of the large cages containing ethane molecules.

  5. Potential for cometabolic biodegradation of 1,4-dioxane in aquifers with methane or ethane as primary substrates.

    PubMed

    Hatzinger, Paul B; Banerjee, Rahul; Rezes, Rachael; Streger, Sheryl H; McClay, Kevin; Schaefer, Charles E

    2017-12-01

    The objective of this research was to evaluate the potential for two gases, methane and ethane, to stimulate the biological degradation of 1,4-dioxane (1,4-D) in groundwater aquifers via aerobic cometabolism. Experiments with aquifer microcosms, enrichment cultures from aquifers, mesophilic pure cultures, and purified enzyme (soluble methane monooxygenase; sMMO) were conducted. During an aquifer microcosm study, ethane was observed to stimulate the aerobic biodegradation of 1,4-D. An ethane-oxidizing enrichment culture from these samples, and a pure culture capable of growing on ethane (Mycobacterium sphagni ENV482) that was isolated from a different aquifer also biodegraded 1,4-D. Unlike ethane, methane was not observed to appreciably stimulate the biodegradation of 1,4-D in aquifer microcosms or in methane-oxidizing mixed cultures enriched from two different aquifers. Three different pure cultures of mesophilic methanotrophs also did not degrade 1,4-D, although each rapidly oxidized 1,1,2-trichloroethene (TCE). Subsequent studies showed that 1,4-D is not a substrate for purified sMMO enzyme from Methylosinus trichosporium OB3b, at least not at the concentrations evaluated, which significantly exceeded those typically observed at contaminated sites. Thus, our data indicate that ethane, which is a common daughter product of the biotic or abiotic reductive dechlorination of chlorinated ethanes and ethenes, may serve as a substrate to enhance 1,4-D degradation in aquifers, particularly in zones where these products mix with aerobic groundwater. It may also be possible to stimulate 1,4-D biodegradation in an aerobic aquifer through addition of ethane gas. Conversely, our results suggest that methane may have limited importance in natural attenuation or for enhancing biodegradation of 1,4-D in groundwater environments.

  6. C-12/C-13 Ratio in Ethane on Titan and Implications for Methane's Replenishment

    NASA Technical Reports Server (NTRS)

    Jennings, Donald E.; Romani, Paul N.; Bjoraker, Gordon L.; Sada, Pedro V.; Nixon, Conor A.; Lunsford, Allen W.; Boyle, Robert J.; Hesman, Brigette E.; McCabe, George H.

    2009-01-01

    The C-12/C-13 abundance ratio in ethane in the atmosphere of Titan has been measured at 822 cm(sup -1) from high spectral resolution ground-based observations. The value 89(8), coincides with the telluric standard and also agrees with the ratio seen in the outer planets. It is almost identical to the result for ethane on Titan found by the composite infrared spectrometer (CIRS) on Cassini. The C-12/C-13 ratio for ethane is higher than the ratio measured in atmospheric methane by Cassini/Huygens GCMS, 82.3(l), representing an enrichment of C-12 in the ethane that might be explained by a kinetic isotope effect of approximately 1.1 in the formation of methyl radicals. If methane is being continuously resupplied to balance photochemical destruction, then we expect the isotopic composition in the ethane product to equilibrate at close to the same C-12/C-13 ratio as that in the supply. The telluric value of the ratio in ethane then implies that the methane reservoir is primordial.

  7. The fate of ethane in Titan's hydrocarbon lakes and seas

    NASA Astrophysics Data System (ADS)

    Mousis, Olivier; Lunine, Jonathan I.; Hayes, Alexander G.; Hofgartner, Jason D.

    2016-05-01

    Ethane is expected to be the dominant photochemical product on Titan's surface and, in the absence of a process that sequesters it from exposed surface reservoirs, a major constituent of its lakes and seas. Absorption of Cassini's 2.2 cm radar by Ligeia Mare however suggests that this north polar sea is dominated by methane. In order to explain this apparent ethane deficiency, we explore the possibility that Ligeia Mare is the visible part of an alkanofer that interacted with an underlying clathrate layer and investigate the influence of this interaction on an assumed initial ethane-methane mixture in the liquid phase. We find that progressive liquid entrapment in clathrate allows the surface liquid reservoir to become methane-dominated for any initial ethane mole fraction below 0.75. If interactions between alkanofers and clathrates are common on Titan, this should lead to the emergence of many methane-dominated seas or lakes.

  8. The presence of functional groups key for biodegradation in ionic liquids: effect on gas solubility.

    PubMed

    Deng, Yun; Morrissey, Saibh; Gathergood, Nicholas; Delort, Anne-Marie; Husson, Pascale; Costa Gomes, Margarida F

    2010-03-22

    The effect of the incorporation of either ester or ester and ether functions into the side chain of an 1-alkyl-3-methylimidazolium cation on the physico-chemical properties of ionic liquids containing bis(trifluoromethylsulfonyl)imide or octylsulfate anions is studied. It is believed that the introduction of an ester function into the cation of the ionic liquids greatly increases their biodegradability. The density of three such ionic liquids is measured as a function of temperature, and the solubility of four gases-carbon dioxide, ethane, methane, and hydrogen-is determined between 303 K and 343 K and at pressures close to atmospheric level. Carbon dioxide is the most soluble gas, followed by ethane and methane; the mole fraction solubilities vary from 1.8 x 10(-3) to 3.7 x 10(-2). These solubilities are of the same order of magnitude as those determined for alkylimidazolium-based ionic liquids. The chemical modification of the alkyl side chain does not result in a significant change of the solvation properties of the ionic liquid. All of the solubilities decrease with increasing temperature, corresponding to an exothermal solvation process. From the variation of this property with temperature, the thermodynamic functions of solvation (Gibbs energy, enthalpy, and entropy) are calculated and provide information about the solute-solvent interactions and the molecular structure of the solutions.

  9. Methane, Black Carbon, and Ethane Emissions from Natural Gas Flares in the Bakken Shale, North Dakota.

    PubMed

    Gvakharia, Alexander; Kort, Eric A; Brandt, Adam; Peischl, Jeff; Ryerson, Thomas B; Schwarz, Joshua P; Smith, Mackenzie L; Sweeney, Colm

    2017-05-02

    Incomplete combustion during flaring can lead to production of black carbon (BC) and loss of methane and other pollutants to the atmosphere, impacting climate and air quality. However, few studies have measured flare efficiency in a real-world setting. We use airborne data of plume samples from 37 unique flares in the Bakken region of North Dakota in May 2014 to calculate emission factors for BC, methane, ethane, and combustion efficiency for methane and ethane. We find no clear relationship between emission factors and aircraft-level wind speed or between methane and BC emission factors. Observed median combustion efficiencies for methane and ethane are close to expected values for typical flares according to the US EPA (98%). However, we find that the efficiency distribution is skewed, exhibiting log-normal behavior. This suggests incomplete combustion from flares contributes almost 1/5 of the total field emissions of methane and ethane measured in the Bakken shale, more than double the expected value if 98% efficiency was representative. BC emission factors also have a skewed distribution, but we find lower emission values than previous studies. The direct observation for the first time of a heavy-tail emissions distribution from flares suggests the need to consider skewed distributions when assessing flare impacts globally.

  10. The Formation of Ethane from Carbon Dioxide under Cold Plasma

    NASA Astrophysics Data System (ADS)

    Zhang, Xiu-ling; Zhang, Lin; Dai, Bin; Gong, Wei-min; Liu, Chang-hou

    2001-04-01

    Pulsed-corona plasma has been used as a new method for ethane dehydrogenation at low temperature and normal pressure using carbon dioxide as an oxidant in this paper. The effect of carbon dioxide content in the feed, power input, and flow rate of the reactants on the ethane dehydrogenation has been investigated. The experimental results show that the conversion of ethane increases with the increase in the amount of carbon dioxide in the feed. The yield of ethylene and acetylene decreases with the increase in the yield of carbon monoxide, indicating that the increased carbon dioxide leads to the part of ethylene and acetylene being oxidized to carbon monoxide. Power input is primarily an electrical parameter in pulsed-corona plasma, which plays an important role in reactant conversion and product formation. When the power input reaches 16 W, ethane conversion is 41.0% and carbon dioxide conversion is 26.3%. The total yield of ethylene and acetylene is 15.6%. The reduced flow rate of feed improves the conversion of ethane, carbon dioxide and the yield of acetylene, and induces carbon deposit as well.

  11. Ground truthing for methane hotspots at Railroad Valley, NV - application to Mars

    NASA Astrophysics Data System (ADS)

    Detweiler, A. M.; Kelley, C. A.; Bebout, B.; McKay, C. P.; DeMarines, J.; Yates, E. L.; Iraci, L. T.

    2011-12-01

    During the 2010 Greenhouse gas Observing SATellite (GOSAT) calibration and validation campaign at Railroad Valley (RRV) playa, NV, unexpected methane and carbon dioxide fluctuations were observed at the dry lakebed. Possible sources included the presence of natural gas (thermogenic methane) from oil deposits in the surrounding playa, and/or methane production from microbial activity (biogenic) in the subsurface of the playa. In the summer of 2011, measurements were undertaken to identify potential methane sources at RRV. The biogenicity of the methane was determined based on δ13C values and methane/ethane ratios. Soil gas samples and sediments were collected at different sites in the playa and surrounding areas. The soils of the playa consist of a surface crust layer (upper ~ 10 cm) grading to a dense clay below about 25 cm. Soil gas from the playa, sampled at about 20 and 80 cm depths, reflected atmospheric methane concentrations, ranging from 2 to 2.4 ppm, suggesting that no methane was produced within the playa. Natural springs on the northeast and western border of the playa, detected as methane hotspots from a flyover by the Sensor Integrated Environmental Remote Research Aircraft (SIERRA), were also sampled. Bubbles in these springs had methane concentrations that ranged from 69 to 84% by volume. In addition, ethane was detected at very low concentrations, giving methane/ethane ratios in excess of 100,000, indicating biogenic methane in the springs. Soils and sediments collected at the playa and spring sites were incubated in vials over a period of ~23 days. Methane production was observed in the spring sites (avg. 228.6 ± 49.1 nmol/g/d at Kate Springs), but was not evident for the playa sites. The incubation data, therefore, corroborated in situ methane concentration measurements. Particulate organic carbon (POC) was low for all sites samples (0.05-0.38%), with the exception of Kate Springs, which had a much higher POC concentration of 3.4 ± 0.7%. Temperature and relative humidity sensors were placed in the playa at 5, 20, and 30 cm below the surface. Since the relative humidity neared 100% (down to 20 cm below the surface), high enough to support microbial life, the observed absence of methane production in the playa itself is likely due to the low POC content, compared to other methane-producing environments. The spatial distribution of methane in combination with the spectral reflectance at the RRV dry lakebed makes it a good Mars analog. The ground truthing and satellite calibration work accomplished at RRV is a good exercise in preparation to identifying the origins of methane observed in the atmosphere of Mars during the upcoming 2012 Mars Science Laboratory and 2016 ExoMars Trace Gas Orbiter missions.

  12. Recent decreases in fossil-fuel emissions of ethane and methane derived from firn air.

    PubMed

    Aydin, Murat; Verhulst, Kristal R; Saltzman, Eric S; Battle, Mark O; Montzka, Stephen A; Blake, Donald R; Tang, Qi; Prather, Michael J

    2011-08-10

    Methane and ethane are the most abundant hydrocarbons in the atmosphere and they affect both atmospheric chemistry and climate. Both gases are emitted from fossil fuels and biomass burning, whereas methane (CH(4)) alone has large sources from wetlands, agriculture, landfills and waste water. Here we use measurements in firn (perennial snowpack) air from Greenland and Antarctica to reconstruct the atmospheric variability of ethane (C(2)H(6)) during the twentieth century. Ethane levels rose from early in the century until the 1980s, when the trend reversed, with a period of decline over the next 20 years. We find that this variability was primarily driven by changes in ethane emissions from fossil fuels; these emissions peaked in the 1960s and 1970s at 14-16 teragrams per year (1 Tg = 10(12) g) and dropped to 8-10 Tg  yr(-1) by the turn of the century. The reduction in fossil-fuel sources is probably related to changes in light hydrocarbon emissions associated with petroleum production and use. The ethane-based fossil-fuel emission history is strikingly different from bottom-up estimates of methane emissions from fossil-fuel use, and implies that the fossil-fuel source of methane started to decline in the 1980s and probably caused the late twentieth century slow-down in the growth rate of atmospheric methane.

  13. Measured temperature and pressure dependence of Vp and Vs in compacted, polycrystalline sI methane and sII methane-ethane hydrate

    USGS Publications Warehouse

    Helgerud, M.B.; Waite, W.F.; Kirby, S.H.; Nur, A.

    2003-01-01

    We report on compressional- and shear-wave-speed measurements made on compacted polycrystalline sI methane and sII methane-ethane hydrate. The gas hydrate samples are synthesized directly in the measurement apparatus by warming granulated ice to 17??C in the presence of a clathrate-forming gas at high pressure (methane for sI, 90.2% methane, 9.8% ethane for sII). Porosity is eliminated after hydrate synthesis by compacting the sample in the synthesis pressure vessel between a hydraulic ram and a fixed end-plug, both containing shear-wave transducers. Wave-speed measurements are made between -20 and 15??C and 0 to 105 MPa applied piston pressure.

  14. 40 CFR 60.565 - Reporting and recordkeeping requirements.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... emission control efficiency of a combustion device or the outlet concentration of TOC (minus methane and... performance test period, and (ii) The percent reduction of TOC (minus methane and ethane) achieved by the incinerator, the concentration of TOC (minus methane and ethane) (ppmv, by compound) at the outlet of the...

  15. 40 CFR 60.565 - Reporting and recordkeeping requirements.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... emission control efficiency of a combustion device or the outlet concentration of TOC (minus methane and... performance test period, and (ii) The percent reduction of TOC (minus methane and ethane) achieved by the incinerator, the concentration of TOC (minus methane and ethane) (ppmv, by compound) at the outlet of the...

  16. 40 CFR 60.565 - Reporting and recordkeeping requirements.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... emission control efficiency of a combustion device or the outlet concentration of TOC (minus methane and... performance test period, and (ii) The percent reduction of TOC (minus methane and ethane) achieved by the incinerator, the concentration of TOC (minus methane and ethane) (ppmv, by compound) at the outlet of the...

  17. 40 CFR 60.565 - Reporting and recordkeeping requirements.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... emission control efficiency of a combustion device or the outlet concentration of TOC (minus methane and... performance test period, and (ii) The percent reduction of TOC (minus methane and ethane) achieved by the incinerator, the concentration of TOC (minus methane and ethane) (ppmv, by compound) at the outlet of the...

  18. 40 CFR 60.565 - Reporting and recordkeeping requirements.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... emission control efficiency of a combustion device or the outlet concentration of TOC (minus methane and... performance test period, and (ii) The percent reduction of TOC (minus methane and ethane) achieved by the incinerator, the concentration of TOC (minus methane and ethane) (ppmv, by compound) at the outlet of the...

  19. Dissociation behavior of methane--ethane mixed gas hydrate coexisting structures I and II.

    PubMed

    Kida, Masato; Jin, Yusuke; Takahashi, Nobuo; Nagao, Jiro; Narita, Hideo

    2010-09-09

    Dissociation behavior of methane-ethane mixed gas hydrate coexisting structures I and II at constant temperatures less than 223 K was studied with use of powder X-ray diffraction and solid-state (13)C NMR techniques. The diffraction patterns at temperatures less than 203 K showed both structures I and II simultaneously convert to Ih during the dissociation, but the diffraction pattern at temperatures greater than 208 K showed different dissociation behavior between structures I and II. Although the diffraction peaks from structure II decreased during measurement at constant temperatures greater than 208 K, those from structure I increased at the initial step of dissociation and then disappeared. This anomalous behavior of the methane-ethane mixed gas hydrate coexisting structures I and II was examined by using the (13)C NMR technique. The (13)C NMR spectra revealed that the anomalous behavior results from the formation of ethane-rich structure I. The structure I hydrate formation was associated with the dissociation rate of the initial methane-ethane mixed gas hydrate.

  20. Partial oxidation of methane by pulsed corona discharges

    NASA Astrophysics Data System (ADS)

    Hoeben, W. F. L. M.; Boekhoven, W.; Beckers, F. J. C. M.; van Heesch, E. J. M.; Pemen, A. J. M.

    2014-09-01

    Pulsed corona-induced partial oxidation of methane in humid oxygen or carbon dioxide atmospheres has been investigated for future fuel synthesis applications. The obtained product spectrum is wide, i.e. saturated, unsaturated and oxygen-functional hydrocarbons. The generally observed methane conversion levels are 6-20% at a conversion efficiency of about 100-250 nmol J-1. The main products are ethane, ethylene and acetylene. Higher saturated hydrocarbons up to C6 have been detected. The observed oxygen-functional hydrocarbons are methanol, ethanol and lower concentrations of aldehydes, ketones, dimethylether and methylformate. Methanol seems to be exclusively produced with CH4/O2 mixtures at a maximum production efficiency of 0.35 nmol J-1. CH4/CO2 mixtures appear to yield higher hydrocarbons. Carboxylic acids appear to be mainly present in the aqueous reactor phase, possibly together with higher molecular weight species.

  1. Airborne Ethane Observations in the Barnett Shale: Quantification of Ethane Flux and Attribution of Methane Emissions.

    PubMed

    Smith, Mackenzie L; Kort, Eric A; Karion, Anna; Sweeney, Colm; Herndon, Scott C; Yacovitch, Tara I

    2015-07-07

    We present high time resolution airborne ethane (C2H6) and methane (CH4) measurements made in March and October 2013 as part of the Barnett Coordinated Campaign over the Barnett Shale formation in Texas. Ethane fluxes are quantified using a downwind flight strategy, a first demonstration of this approach for C2H6. Additionally, ethane-to-methane emissions ratios (C2H6:CH4) of point sources were observationally determined from simultaneous airborne C2H6 and CH4 measurements during a survey flight over the source region. Distinct C2H6:CH4 × 100% molar ratios of 0.0%, 1.8%, and 9.6%, indicative of microbial, low-C2H6 fossil, and high-C2H6 fossil sources, respectively, emerged in observations over the emissions source region of the Barnett Shale. Ethane-to-methane correlations were used in conjunction with C2H6 and CH4 fluxes to quantify the fraction of CH4 emissions derived from fossil and microbial sources. On the basis of two analyses, we find 71-85% of the observed methane emissions quantified in the Barnett Shale are derived from fossil sources. The average ethane flux observed from the studied region of the Barnett Shale was 6.6 ± 0.2 × 10(3) kg hr(-1) and consistent across six days in spring and fall of 2013.

  2. 40 CFR 60.612 - Standards.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... maximum production rate at which the affected facility will be operated, or 180 days after the initial... (minus methane and ethane) by 98 weight-percent, or to a TOC (minus methane and ethane) concentration of...

  3. 40 CFR 60.612 - Standards.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... maximum production rate at which the affected facility will be operated, or 180 days after the initial... (minus methane and ethane) by 98 weight-percent, or to a TOC (minus methane and ethane) concentration of...

  4. 40 CFR 60.612 - Standards.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... maximum production rate at which the affected facility will be operated, or 180 days after the initial... (minus methane and ethane) by 98 weight-percent, or to a TOC (minus methane and ethane) concentration of...

  5. 40 CFR 60.612 - Standards.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... maximum production rate at which the affected facility will be operated, or 180 days after the initial... (minus methane and ethane) by 98 weight-percent, or to a TOC (minus methane and ethane) concentration of...

  6. 40 CFR 60.612 - Standards.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... start-up, whichever date comes first. Each owner or operator shall either: (a) Reduce emissions of TOC (minus methane and ethane) by 98 weight-percent, or to a TOC (minus methane and ethane) concentration of...

  7. Quantifying the Loss of Processed Natural Gas Within California's South Coast Air Basin Using Long-term Measurements of Ethane and Methane

    NASA Astrophysics Data System (ADS)

    Wunch, D.; Toon, G. C.; Hedelius, J.; Vizenor, N.; Roehl, C. M.; Saad, K.; Blavier, J. F.; Blake, D. R.; Wennberg, P. O.

    2016-12-01

    In California's South Coast Air Basin (SoCAB), the methane emissions inferred from atmospheric measurements exceed estimates based on inventories. We seek to provide insight into the sources of the discrepancy with two records of atmospheric trace gas total column abundances in the SoCAB: one temporally sparse dataset that began in the late 1980s, and a temporally dense dataset that began in 2012. We use their measurements of ethane and methane to partition the sources of the excess methane. The early few years of the sparse record show a rapid decline in ethane emissions at a much faster rate than decreasing vehicle exhaust or natural gas and crude oil production can explain. Between 2010 and 2015, ethane emissions have grown gradually, which is in contrast to the steady production of natural gas liquids over that time. Since 2012, ethane to methane ratios in the natural gas withdrawn from a storage facility within the SoCAB have been increasing; these ratios are tracked in our atmospheric measurements with about half of the rate of increase. From this, we infer that about half of the excess methane in the SoCAB between 2012-­2015 is attributable to losses from the natural gas infrastructure.

  8. Methane, Ethane, and Nitrogen Stability on Titan

    NASA Astrophysics Data System (ADS)

    Hanley, J.; Grundy, W. M.; Thompson, G.; Dustrud, S.; Pearce, L.; Lindberg, G.; Roe, H. G.; Tegler, S.

    2017-12-01

    Many outer solar system bodies are likely to have a combination of methane, ethane and nitrogen. In particular the lakes of Titan are known to consist of these species. Understanding the past and current stability of these lakes requires characterizing the interactions of methane and ethane, along with nitrogen, as both liquids and ices. Our cryogenic laboratory setup allows us to explore ices down to 30 K through imaging, and transmission and Raman spectroscopy. Our recent work has shown that although methane and ethane have similar freezing points, when mixed they can remain liquid down to 72 K. Concurrently with the freezing point measurements we acquire transmission or Raman spectra of these mixtures to understand how the structural features change with concentration and temperature. Any mixing of these two species together will depress the freezing point of the lake below Titan's surface temperature, preventing them from freezing. We will present new results utilizing our recently acquired Raman spectrometer that allow us to explore both the liquid and solid phases of the ternary system of methane, ethane and nitrogen. In particular we will explore the effect of nitrogen on the eutectic of the methane-ethane system. At high pressure we find that the ternary creates two separate liquid phases. Through spectroscopy we determined the bottom layer to be nitrogen rich, and the top layer to be ethane rich. Identifying the eutectic, as well as understanding the liquidus and solidus points of combinations of these species, has implications for not only the lakes on the surface of Titan, but also for the evaporation/condensation/cloud cycle in the atmosphere, as well as the stability of these species on other outer solar system bodies. These results will help interpretation of future observational data, and guide current theoretical models.

  9. The Global Search for Abiogenic GHGs, via Methane Isotopes and Ethane

    NASA Astrophysics Data System (ADS)

    Malina, Edward; Muller, Jan-Peter; Walton, David; Potts, Dale

    2015-04-01

    The importance of Methane as an anthropogenic Green House Gas (GHG) is well recognized in the scientific community, and is second only to Carbon Dioxide in terms of influence on the Earth's radiation budget (Parker, et al, 2011) suggesting that the ability to apportion the source of the methane (whether it is biogenic, abiogenic or thermogenic) has never been more important. It has been proposed (Etiope, 2009) that it may be possible to distinguish between a biogenic methane source (e.g. bacteria fermentation) and an abiogenic source (e.g. gas seepage or fugitive emissions) via the retrieval of the abundances of methane isotopes (12CH4 and 13CH4) and through the ratio of ethane (C2H6) to methane (CH4) concentrations. Using ultra fine spectroscopy (<0.2cm-1 spectral resolution) from Fourier Transform Spectrometers (FTS) based on the SCISAT-1 (ACE-FTS) and GOSAT (TANSO-FTS) we are developing a retrieval scheme to map global emissions of abiogenic and biogenic methane, and provide insight into how these variations in methane might drive atmospheric chemistry, focusing on the lower levels of the atmosphere. Using HiTran2012 simulations, we show that it is possible to distinguish between methane isotopes using the FTS based instruments on ACE and GOSAT, and retrieve the abundances in the Short Wave Infra-red (SWIR) at 1.65μm, 2.3μm, 3.3μm and Thermal IR, 7.8μm wavebands for methane, and the 3.3μm and 7μm wavebands for ethane. Initially we use the spectral line database HITRAN to determine the most appropriate spectral waveband to retrieve methane isotopes (and ethane) with minimal water vapour, CO2 and NO2 impact. Following this, we have evaluated the detectability of these trace gases using the more sophisticated Radiative Transfer Models (RTMs) SCIATRAN, the Oxford RFM and MODTRAN 5 in the SWIR, in order to determine the barriers to retrieving methane isotopes in both ACE (limb profile) and GOSAT (nadir measurements) instruments, including a preliminary investigation into the effects of clouds, aerosols, surface reflectance on the retrieval of methane isotopes. The aim of these RTM simulations is to further narrow down the spectral regions (originally identified in the HITRAN assessment) where methane isotopes can/may be retrieved from orbit. The key outputs from the RTM study are absorption and radiance data, which allow us to identify the cleanest methane regions, and the likely SNR achievable in these regions. Finally we show some of the results of a study where we compare the output from each of the RTMs used in this study (SCIATRAN, ORFM and MODTRAN), in order to gain some confidence and insight into the strengths and weaknesses of the RTM outputs, using MODTRAN as a benchmark. References: Bernath, P. F. (2005). Atmospheric Chemistry Experiment (ACE): Mission overview. Geophys. Res. Lett. 32: L15S01. Etiope, G. (2009). Natural emissions of methane from geological seepage in Europe. Atmospheric Environment Journal. 2009 vol. 43(7) pp. 1430-1443. JAXA (2012). "Overview of the "IBUKI"(GOSAT)." Retrieved 05-03-2014, 2014, from http://www.jaxa.jp/countdown/f15/overview/ibuki_e.html. Parker, R, et al (2011). GOSAT "Proxy" Methane v4 - Updated March 2013. Accessed 11/04/14 at 08:13. URL: http://www.leos.le.ac.uk/GHG/data/styled/index.html.

  10. 40 CFR 60.702 - Standards.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... first. Each owner or operator shall either: (a) Reduce emissions of TOC (less methane and ethane) by 98 weight-percent, or to a TOC (less methane and ethane) concentration of 20 ppmv, on a dry basis corrected...

  11. 40 CFR 60.662 - Standards.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., whichever date comes first. Each owner or operator shall either: (a) Reduce emissions of TOC (less methane and ethane) by 98 weight-percent, or to a TOC (less methane and ethane) concentration of 20 ppmv, on a...

  12. Reactions of O/1D/ with methane and ethane.

    NASA Technical Reports Server (NTRS)

    Lin, C.-L.; Demore, W. B.

    1973-01-01

    Mixtures of nitrous oxide and methane and mixtures of nitrous oxide and ethane were photolyzed with 1849-A light. The reaction products were analyzed chromatographically. It was found that the reaction of the excited atomic oxygen with methane gives mainly CH3 and OH radicals as initial products, along with about 9% of formaldehyde and molecular hydrogen. The reaction of the excited atomic oxygen with ethane gives C2H5, OH, CH3 and CH2OH as major initial products, with only a few per cent of molecular hydrogen.

  13. Variability of Neptune's 12.2-micron ethane emission feature

    NASA Technical Reports Server (NTRS)

    Hammel, H. B.; Young, Leslie A.; Hackwell, J.; Lynch, D. K.; Russell, R.; Orton, Glenn S.

    1992-01-01

    It is presently shown that the ratio of ethane emission to methane emission in Neptune's 7-14 micron spectrum increased by a factor of 1.47 +/- 0.11 in the period between 1985 and 1991, and that the 12.2-micron ethan feature (rather than that of methane at 7.7 microns) is implicated in the greater part of that change. It is speculated that this variation is due either to a nonuniform increase in stratospheric temperature, or (more likely) to an increase in the ethane concentration by over 15 percent.

  14. Ethane: A Key to Evaluating Natural Gas Industrial Emissions

    NASA Astrophysics Data System (ADS)

    Yacovitch, T. I.; Herndon, S. C.; Agnese, M.; Roscioli, J. R.; Floerchinger, C. R.; Knighton, W. B.; Pusede, S. E.; Diskin, G. S.; DiGangi, J. P.; Sachse, G. W.; Eichler, P.; Mikoviny, T.; Müller, M.; Wisthaler, A.; Conley, S. A.; Petron, G.

    2014-12-01

    Airborne and mobile-surface measurements of ethane at 1Hz in the Denver-Julesberg oil and gas production basin in NE Colorado reveal a rich set of emission sources and magnitudes. Although ethane has only a mild influence on hemispheric ozone levels, it is often co-emitted with larger hydrocarbons including hazardous air pollutants (HAPs) and ozone precursors that impact local and regional air quality. Ethane/methane enhancement ratios provide a map of expected emission source types in different areas around greater Denver. Links are drawn between the ethane content of isolated methane emission plumes and the prevalence of concomitant HAP and ozone precursor species. The efficacy of using ethane as a dilution tracer specific to the oil & gas footprint will be demonstrated.

  15. 40 CFR 63.7893 - How do I demonstrate continuous compliance with the emissions limitations and work practice...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ...(b)(2), you maintain emissions of TOC (minus methane and ethane) from all affected process vents at...), you maintain that the emissions of TOC (minus methane and ethane) from all affected process vents are...

  16. Fundamental studies on kinetic isotope effect (KIE) of hydrogen isotope fractionation in natural gas systems

    USGS Publications Warehouse

    Ni, Y.; Ma, Q.; Ellis, G.S.; Dai, J.; Katz, B.; Zhang, S.; Tang, Y.

    2011-01-01

    Based on quantum chemistry calculations for normal octane homolytic cracking, a kinetic hydrogen isotope fractionation model for methane, ethane, and propane formation is proposed. The activation energy differences between D-substitute and non-substituted methane, ethane, and propane are 318.6, 281.7, and 280.2cal/mol, respectively. In order to determine the effect of the entropy contribution for hydrogen isotopic substitution, a transition state for ethane bond rupture was determined based on density function theory (DFT) calculations. The kinetic isotope effect (KIE) associated with bond rupture in D and H substituted ethane results in a frequency factor ratio of 1.07. Based on the proposed mathematical model of hydrogen isotope fractionation, one can potentially quantify natural gas thermal maturity from measured hydrogen isotope values. Calculated gas maturity values determined by the proposed mathematical model using ??D values in ethane from several basins in the world are in close agreement with similar predictions based on the ??13C composition of ethane. However, gas maturity values calculated from field data of methane and propane using both hydrogen and carbon kinetic isotopic models do not agree as closely. It is possible that ??D values in methane may be affected by microbial mixing and that propane values might be more susceptible to hydrogen exchange with water or to analytical errors. Although the model used in this study is quite preliminary, the results demonstrate that kinetic isotope fractionation effects in hydrogen may be useful in quantitative models of natural gas generation, and that ??D values in ethane might be more suitable for modeling than comparable values in methane and propane. ?? 2011 Elsevier Ltd.

  17. Identification of Novel Methane-, Ethane-, and Propane-Oxidizing Bacteria at Marine Hydrocarbon Seeps by Stable Isotope Probing ▿ †

    PubMed Central

    Redmond, Molly C.; Valentine, David L.; Sessions, Alex L.

    2010-01-01

    Marine hydrocarbon seeps supply oil and gas to microorganisms in sediments and overlying water. We used stable isotope probing (SIP) to identify aerobic bacteria oxidizing gaseous hydrocarbons in surface sediment from the Coal Oil Point seep field located offshore of Santa Barbara, California. After incubating sediment with 13C-labeled methane, ethane, or propane, we confirmed the incorporation of 13C into fatty acids and DNA. Terminal restriction fragment length polymorphism (T-RFLP) analysis and sequencing of the 16S rRNA and particulate methane monooxygenase (pmoA) genes in 13C-DNA revealed groups of microbes not previously thought to contribute to methane, ethane, or propane oxidation. First, 13C methane was primarily assimilated by Gammaproteobacteria species from the family Methylococcaceae, Gammaproteobacteria related to Methylophaga, and Betaproteobacteria from the family Methylophilaceae. Species of the latter two genera have not been previously shown to oxidize methane and may have been cross-feeding on methanol, but species of both genera were heavily labeled after just 3 days. pmoA sequences were affiliated with species of Methylococcaceae, but most were not closely related to cultured methanotrophs. Second, 13C ethane was consumed by members of a novel group of Methylococcaceae. Growth with ethane as the major carbon source has not previously been observed in members of the Methylococcaceae; a highly divergent pmoA-like gene detected in the 13C-labeled DNA may encode an ethane monooxygenase. Third, 13C propane was consumed by members of a group of unclassified Gammaproteobacteria species not previously linked to propane oxidation. This study identifies several bacterial lineages as participants in the oxidation of gaseous hydrocarbons in marine seeps and supports the idea of an alternate function for some pmoA-like genes. PMID:20675448

  18. Identification of novel methane-, ethane-, and propane-oxidizing bacteria at marine hydrocarbon seeps by stable isotope probing.

    PubMed

    Redmond, Molly C; Valentine, David L; Sessions, Alex L

    2010-10-01

    Marine hydrocarbon seeps supply oil and gas to microorganisms in sediments and overlying water. We used stable isotope probing (SIP) to identify aerobic bacteria oxidizing gaseous hydrocarbons in surface sediment from the Coal Oil Point seep field located offshore of Santa Barbara, California. After incubating sediment with (13)C-labeled methane, ethane, or propane, we confirmed the incorporation of (13)C into fatty acids and DNA. Terminal restriction fragment length polymorphism (T-RFLP) analysis and sequencing of the 16S rRNA and particulate methane monooxygenase (pmoA) genes in (13)C-DNA revealed groups of microbes not previously thought to contribute to methane, ethane, or propane oxidation. First, (13)C methane was primarily assimilated by Gammaproteobacteria species from the family Methylococcaceae, Gammaproteobacteria related to Methylophaga, and Betaproteobacteria from the family Methylophilaceae. Species of the latter two genera have not been previously shown to oxidize methane and may have been cross-feeding on methanol, but species of both genera were heavily labeled after just 3 days. pmoA sequences were affiliated with species of Methylococcaceae, but most were not closely related to cultured methanotrophs. Second, (13)C ethane was consumed by members of a novel group of Methylococcaceae. Growth with ethane as the major carbon source has not previously been observed in members of the Methylococcaceae; a highly divergent pmoA-like gene detected in the (13)C-labeled DNA may encode an ethane monooxygenase. Third, (13)C propane was consumed by members of a group of unclassified Gammaproteobacteria species not previously linked to propane oxidation. This study identifies several bacterial lineages as participants in the oxidation of gaseous hydrocarbons in marine seeps and supports the idea of an alternate function for some pmoA-like genes.

  19. 40 CFR 63.496 - Back-end process provisions-procedures to determine compliance using control or recovery devices.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... total organic HAP (or TOC, minus methane and ethane) emissions in all process vent streams and primary... TOC (minus methane and ethane) may be measured instead of total organic HAP. (C) The mass rates shall... and outlet of the control device shall be the sum of all total organic HAP (or TOC, minus methane and...

  20. 40 CFR 63.7926 - How do I demonstrate initial compliance with the emission limitations and work practice standards...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... subpart or TOC (minus methane and ethane) from the control device, measured or determined according to the... of this subpart or TOC (minus methane and ethane) from the combustion control device, measured by a...

  1. Rapid and Simple Capillary-Rise/Vanishing Interfacial Tension Method To Determine Crude Oil Minimum Miscibility Pressure: Pure and Mixed CO 2, Methane, and Ethane

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

    Hawthorne, Steven B.; Miller, David J.; Jin, Lu

    Here, we report a simplification of the capillary-rise/vanishing interfacial tension (IFT) method to measure minimum miscibility pressure (MMP) based on only requiring knowledge of when the interfacial tension approaches zero. Simply measuring the height of the crude oil in a capillary at several pressures from ambient to near the MMP pressure and extrapolating the oil height versus pressure plot to zero oil height yields the MMP without the need of the additional instrumentation and labor required to perform actual IFT measurements. A total of 2-4 MMP values can be determined per day with only one experimental apparatus, and the methodmore » greatly reduces the initial cost and complexity of the required instrumentation. The use of three capillaries having different inner diameters allows for triplicate determinations of MMP from each experiment. Because the actual MMP pressure need not be reached during the experiment, MMP values that exceed the pressure ratings of the equipment can be reasonably estimated (e.g., MMPs using pure nitrogen). The method was used to determine the MMP pressure for crude oil samples from a conventional Muddy Formation reservoir in the Powder River Basin [American Petroleum Institute (API) gravity of 35.8°] and an unconventional Bakken Formation reservoir in the Williston Basin (API gravity of 38.7°). The method is reproducible [typically <4% relative standard deviation (RSD)], and the method gave good agreement for a “live” Bakken oil with the results from a slim tube test of a commercial laboratory. Approximately 80 MMP values were measured using pure CO 2, methane, and ethane as well as 0-100% mole ratios of methane/CO 2 and methane/ethane. For both oil samples, ethane MMPs were ca. one-half those with CO 2, while methane MMPs were ca. double or triple those with CO 2. MMPs with mixed methane/CO 2 showed a linear increase with mole percent methane for both crude oils, while both oils showed an exponential increase in MMP with mole percent methane in ethane, with a little increase in MMP until ca. 20 mol % methane in ethane.« less

  2. Rapid and Simple Capillary-Rise/Vanishing Interfacial Tension Method To Determine Crude Oil Minimum Miscibility Pressure: Pure and Mixed CO 2, Methane, and Ethane

    DOE PAGES

    Hawthorne, Steven B.; Miller, David J.; Jin, Lu; ...

    2016-07-10

    Here, we report a simplification of the capillary-rise/vanishing interfacial tension (IFT) method to measure minimum miscibility pressure (MMP) based on only requiring knowledge of when the interfacial tension approaches zero. Simply measuring the height of the crude oil in a capillary at several pressures from ambient to near the MMP pressure and extrapolating the oil height versus pressure plot to zero oil height yields the MMP without the need of the additional instrumentation and labor required to perform actual IFT measurements. A total of 2-4 MMP values can be determined per day with only one experimental apparatus, and the methodmore » greatly reduces the initial cost and complexity of the required instrumentation. The use of three capillaries having different inner diameters allows for triplicate determinations of MMP from each experiment. Because the actual MMP pressure need not be reached during the experiment, MMP values that exceed the pressure ratings of the equipment can be reasonably estimated (e.g., MMPs using pure nitrogen). The method was used to determine the MMP pressure for crude oil samples from a conventional Muddy Formation reservoir in the Powder River Basin [American Petroleum Institute (API) gravity of 35.8°] and an unconventional Bakken Formation reservoir in the Williston Basin (API gravity of 38.7°). The method is reproducible [typically <4% relative standard deviation (RSD)], and the method gave good agreement for a “live” Bakken oil with the results from a slim tube test of a commercial laboratory. Approximately 80 MMP values were measured using pure CO 2, methane, and ethane as well as 0-100% mole ratios of methane/CO 2 and methane/ethane. For both oil samples, ethane MMPs were ca. one-half those with CO 2, while methane MMPs were ca. double or triple those with CO 2. MMPs with mixed methane/CO 2 showed a linear increase with mole percent methane for both crude oils, while both oils showed an exponential increase in MMP with mole percent methane in ethane, with a little increase in MMP until ca. 20 mol % methane in ethane.« less

  3. The Soil Microbial Response to a Massive Natural Gas Leak

    NASA Astrophysics Data System (ADS)

    Tavormina, P. L.; Newman, S.; Shen, L.; Connon, S. A.; Okumura, M.; Orphan, V. J.

    2016-12-01

    The 2015/2016 gas leak in the Porter Ranch community (Southern California) was the largest natural gas leak in US history. While considerable attention has focused on the amount of methane released to the atmosphere and the effects of other gas components on human well-being, less attention has been given to the response of soil microbes to this event. These microbes represent natural pathways for utilization of C1 compounds in soils and, possibly, untapped potential to remediate natural and anthropogenic gas emissions. We monitored onsite and background soil methane concentrations and microbial communities during and following the Porter Ranch gas leak. Soil core samples (25cm depth, collected twice monthly beginning in January 2016) were preserved for DNA, RNA, microscopic, stable isotope probing, and chromatographic methods. Simultaneously to coring, gas from soil pore spaces was collected for cavity ringdown spectroscopy to measure carbon dioxide, methane and ethane concentrations, and estimate corresponding isotopic values in carbon dioxide and methane. By pairing these measurements with high throughput sequencing, transcript analysis, and cultivation, we demonstrate discrete shifts in the total microbial community in surface (0 - 5 cm) and deep (20 - 25 cm) soils. Importantly, we find that methane consumption likely occurred in surface soils during and following the leak. The lineages most significantly correlated with elevated methane from the leak event were five orders of magnitude more abundant near the leak event in space and time, indicating a microbial bloom. These lineages are previously unrecognized members of Sphingomonadaceae, and they encode at least two biochemical pathways for methane oxidation. Cultivation of the first representative of this group now allows more detailed investigation into its capacity for microbially-mediated soil methane oxidation and mitigation.

  4. Photoabsorption cross sections of methane and ethane, 1380-1600 A, at T equals 295 K and T equals 200 K. [in Jupiter atmosphere

    NASA Technical Reports Server (NTRS)

    Mount, G. H.; Moos, H. W.

    1978-01-01

    Photoabsorption cross sections of methane and ethane have been determined in the wavelength range from 1380 to 1600 A at room (295 K) and dry-ice (200 K) temperatures. It is found that the room-temperature ethane data are in excellent agreement with the older measurements of Okabe and Becker (1963) rather than with more recent determinations and that a small systematic blueshift occurs at the foot of the molecular absorption edges of both gases as the gases are cooled from room temperature to 200 K, a value close to the actual temperature of the Jovian atmosphere. It is concluded that methane photoabsorption will dominate until its cross section is about 0.01 that of ethane, which occurs at about 1440 A, and that ethane should be the dominant photoabsorber in the Jovian atmosphere in the region from above 1440 A to not farther than 1575 A.

  5. 40 CFR 63.7891 - How do I demonstrate initial compliance with the emissions limitations and work practice...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... § 63.7890(b)(2), you demonstrate that emissions of TOC (minus methane and ethane) from all affected... elect to meet § 63.7890(b)(4), you demonstrate that the emissions of TOC (minus methane and ethane) from...

  6. Sonolysis of hydrocarbons in aqueous solution

    NASA Astrophysics Data System (ADS)

    Hart, Edwin J.; Fischer, Christian-Herbert; Henglein, Arnim

    Water was irradiated with 300 kHz ultrasound under an argon atmosphere containing various amounts of methane and ethane. Limited studies were also made on ethylene, acetylene, propane and butane. The methane and ethane irradiations were carried out over the hydrocarbon-argon range of 2-100%. Maximum decomposition occurs at 15% for methane and 10% for ethane. While hydrogen is a dominant product in both cases, acetylene, ethylene and ethane are prominent products, too. Propane, propene and propin form in lesser quantities. 2-methyl-propane, n-butane, l-butene, 2-methyl-butene, butadiene and n-butin have also been identified. These hydrocarbons are similar to those found in pyrolysis and in fuel rich combustion experiments. Carbon monoxide is an important product at hydrocarbon concentrations less than 40% establishing water was an oxygen delivering reactant under these conditions. In the case of methane, the ratio of ethylene plus acetylene to ethane is used to estimate the effective temperature in the cavitation bubble. A temperature of about 2800 K is obtained for bubbles containing argon (plus water vapor and 20% CH 4) and T = 2000 K for pure methane. The rate of decomposition for unsaturated hydrocarbons is substantially greater than for the saturated ones. Low molecular weight products are mainly formed from saturated hydrocarbons whereas polymerization products are mainly formed from the unsaturated hydrocarbons. The decomposition of acetylene in argon bubbles is one of the fastest sonolytic processes.

  7. Mobile Measurement of Methane and Ethane for the Detection and Attribution of Natural Gas Pipeline Leaks Using Off-Axis Integrated Output Spectroscopy

    NASA Astrophysics Data System (ADS)

    Leen, J. B.; Spillane, S.; Gardner, A.; Hansen, P. C.; Gupta, M.; Baer, D. S.

    2015-12-01

    Natural gas leaks pose a risk to public safety both because of potential explosions as well as from the greenhouse gas potential of fugitive methane. The rapid and cost effective detection of leaks in natural gas distribution is critical to providing a system that is safe for the public and the environment. Detection of methane from a mobile platform (vehicles, aircraft, etc.) is an accepted method of identifying leaks. A robust approach to differentiating pipeline gas (thermogenic) from other biogenic sources is the detection of ethane along with methane. Ethane is present in nearly all thermogenic gas but not in biogenic sources and its presence can be used to positively identify a gas sample. We present a mobile system for the simultaneous measurement of methane and ethane that is capable of detecting pipeline leaks and differentiating pipeline gas from other biogenic sources such as landfills, swamps, sewers, and enteric fermentation. The mobile system consists of a high precision GPS, sonic anemometer, and methane/ethane analyzer based on off-axis integrated cavity output spectroscopy (OA-ICOS). In order to minimize the system cost and facilitate the wide use of mobile leak detection, the analyzer operates in the near-infrared portion of the spectrum where lasers and optics are significantly less costly than in the mid-infrared. The analyzer is capable of detecting methane with a precision of <2 ppb (1σ in 1 sec) and detecting ethane with a precision of <30 ppb (1σ in 1 sec). Additionally, measurement rates of 5 Hz allow for detection of leaks at speeds up to 50 mph. The sonic anemometer, GPS and analyzer inlet are mounted to a generic roof rack for attachment to available fleet vehicles. The system can detect leaks having a downwind concentration of as little as 10 ppb of methane above ambient, while leaks 500 ppb above ambient can be identified as thermogenic with greater than 99% certainty (for gas with 6% ethane). Finally, analysis of wind data provides an estimate of leak direction and distance. The system presented provides a robust, cost effective solution to natural gas leak detection and attribution to maximize safety and minimize greenhouse gas impacts of distribution systems.

  8. In situ gas fuel production during the treatment of textile wastewater at supercritical conditions.

    PubMed

    Kıpçak, Ekin; Akgün, Mesut

    2013-01-01

    Supercritical water gasification has recently received much attention as a potential alternative to energy conversion methods applied to aqueous/non-aqueous biomass sources, industrial wastes or fossil fuels such as coal because of the unique physical properties of water above its critical conditions (i.e. 374.8 °C and 22.1 MPa). This paper presents the results obtained for the hydrothermal gasification of textile wastewater at supercritical conditions. The experiments were carried out at five reaction temperatures (between 450 and 650 °C) and five reaction times (between 30 and 150 s), under a constant pressure of 25 MPa. It was found that the gaseous products contained considerable amounts of hydrogen, carbon monoxide, carbon dioxide, and C(1)-C(4) hydrocarbons, such as methane, ethane, propane and propylene. The maximum amount of the obtained gaseous product was 1.23 mL per mL textile wastewater, at a reaction temperature of 600 °C, with a reaction time of 150 s. At this state, the product comprised 13.02% hydrogen, 38.93% methane, 4.33% ethane, 0.10% propane, 0.01% propylene, 7.97% carbon monoxide, 27.22% carbon dioxide and 8.00% nitrogen. In addition, a 62.88% decrease in the total organic carbon (TOC) content was observed and the color of the wastewater was removed. Moreover, for the hydrothermal decomposition of the textile wastewater, a first-order reaction rate was designated with an activation energy of 50.42 (±2.33) kJ/mol and a pre-exponential factor of 13.29 (±0.41) s(-1).

  9. Dissolution of Hydrocarbon Gas Hydrates in Seawater at 1030-m; Effects of Porosity, Structure, and Compositional Variation as Determined by High-Definition Video and SEM Imaging.

    NASA Astrophysics Data System (ADS)

    Stern, L. A.; Peltzer, E. T.; Durham, W. B.; Kirby, S. H.; Brewer, P. G.; Circone, S.; Rehder, G.

    2002-12-01

    We compare dissolution rates of pure, porous, compacted, and oil-contaminated sI methane hydrate and sII methane-ethane hydrate to rates measured previously on pure, compacted, sI methane hydrate and sI carbon dioxide hydrate (Rehder et al., Fall AGU 2001). Laboratory-synthesized test specimens were used in both studies, allowing characterization of test materials prior to their transport and exposure to seawater at 1030-meter depth on the Monterey Canyon seafloor, off coastal Moss Landing, CA. Although pressure and temperature (P-T) conditions at this site are within the nominal P-T equilibrium fields of all gas hydrates tested here, the seawater is undersaturated with respect to the hydrate-forming gas species. Hence, samples dissolve with time, at a rate dependent on water current flow. Four samples were deployed in this second experiment: (1) pure, 30% porous methane hydrate; (2) pure, compacted methane hydrate; (3) pure methane hydrate compacted and then contaminated with a low-T mineral oil; and (4) pure, compacted sII methane-ethane hydrate with methane:ethane molar ratio 0.72. Samples were transferred by pressure vessel at 0 ° C and 15 MPa to the seafloor observatory via the MBARI remotely operated vehicle Ventana. Samples were then exposed to the deep ocean environment and monitored by HDTV camera for several hours at the beginning and end of a 25-hour period. Local current speed and direction were also measured throughout the experiment. Those samples that did not undergo complete dissolution after 25 h were successfully recovered to the laboratory for subsequent analysis by scanning electron microscopy (SEM). Previously, video analysis showed dissolution rates corresponding to 4.0 +/- 0.5 mmole CO2/m2 s for compacted CO2 hydrate samples, and 0.37 +/- 0.03 mmole CH4/m2s for compacted methane hydrate samples (Rehder et al, AGU 2001). The ratio of dissolution rates fits a simple diffusive boundary layer model that incorporates relative gas solubilities appropriate to the field site. These calculations assume that dissolution occurred only along the outer (i.e. imaged) surface of the samples. This assumption is now validated by SEM analysis of recovered samples from the second dive, showing little to no internal alteration of compacted material following their partial dissolution. Quantitative comparison of results from the two dives poses challenges due to variations in sample size and orientation. However, both compacted methane hydrate samples from the second dive in fact exhibited comparable behavior to that measured in the previous experiment; the oily sample did not dissolve at a slower rate, as might be expected if a hydrophobic contaminant inhibits seawater contact. Surprisingly, the porous methane hydrate exhibited significantly slower face retreat than its compacted counterparts. The sII methane-ethane hydrate dissolved measurably slower than all other samples, consistent with the solubility properties of its guest components. While these results represent only a first step in emulating the more complex interactions of seawater with naturally occurring hydrate-bearing sediments, such end member studies should aid preliminary modelling investigations of the chemical stability and lifetime of gas hydrates exposed at the seafloor.

  10. 40 CFR 63.7890 - What emissions limitations and work practice standards must I meet for process vents?

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... total organic compounds (TOC) (minus methane and ethane) to a level below 1.4 kg/hr and 2.8 Mg/yr (3.0... process vents the emissions of TOC (minus methane and ethane) by 95 percent by weight or more. (c) For...

  11. ANALYSIS OF DISSOLVED METHANE, ETHANE, AND ETHYLENE IN GROUND WATER BY A STANDARD GAS CHROMATOGRAPHIC TECHNIQUE

    EPA Science Inventory

    The measurement of dissolved gases such as methane, ethane, and ethylene in ground water is important in determining whether intrinsic bioremediation is occurring in a fuel- or solvent-contaminated aquifer. A simple procedure is described for the collection and subsequent analys...

  12. Methane source identification in Boston, Massachusetts using isotopic and ethane measurements

    NASA Astrophysics Data System (ADS)

    Down, A.; Jackson, R. B.; Plata, D.; McKain, K.; Wofsy, S. C.; Rella, C.; Crosson, E.; Phillips, N. G.

    2012-12-01

    Methane has substantial greenhouse warming potential and is the principle component of natural gas. Fugitive natural gas emissions could be a significant source of methane to the atmosphere. However, the cumulative magnitude of natural gas leaks is not yet well constrained. We used a combination of point source measurements and ambient monitoring to characterize the methane sources in the Boston urban area. We developed distinct fingerprints for natural gas and multiple biogenic methane sources based on hydrocarbon concentration and isotopic composition. We combine these data with periodic measurements of atmospheric methane and ethane concentration to estimate the fractional contribution of natural gas and biogenic methane sources to the cumulative urban methane flux in Boston. These results are used to inform an inverse model of urban methane concentration and emissions.

  13. 40 CFR 63.1426 - Process vent requirements for determining organic HAP concentration, control efficiency, and...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... National Emission Standards for Hazardous Air Pollutant Emissions for Polyether Polyols Production § 63... percent reduction may be measured as total epoxide, total organic HAP, or as TOC minus methane and ethane... TOC (minus methane and ethane) concentrations in all process vent streams and primary and secondary...

  14. 40 CFR 63.1426 - Process vent requirements for determining organic HAP concentration, control efficiency, and...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... National Emission Standards for Hazardous Air Pollutant Emissions for Polyether Polyols Production § 63... percent reduction may be measured as total epoxide, total organic HAP, or as TOC minus methane and ethane... TOC (minus methane and ethane) concentrations in all process vent streams and primary and secondary...

  15. 40 CFR 63.1426 - Process vent requirements for determining organic HAP concentration, control efficiency, and...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Production § 63.1426 Process vent requirements for determining organic HAP concentration, control efficiency..., total organic HAP, or as TOC minus methane and ethane according to the procedures specified. When... methane and ethane) concentrations in all process vent streams and primary and secondary fuels introduced...

  16. 40 CFR 60.702 - Standards.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... § 60.704 is completed, but not later than 60 days after achieving the maximum production rate at which... first. Each owner or operator shall either: (a) Reduce emissions of TOC (less methane and ethane) by 98 weight-percent, or to a TOC (less methane and ethane) concentration of 20 ppmv, on a dry basis corrected...

  17. 40 CFR 60.702 - Standards.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... § 60.704 is completed, but not later than 60 days after achieving the maximum production rate at which... first. Each owner or operator shall either: (a) Reduce emissions of TOC (less methane and ethane) by 98 weight-percent, or to a TOC (less methane and ethane) concentration of 20 ppmv, on a dry basis corrected...

  18. 40 CFR 60.662 - Standards.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... production rate at which the affected facility will be operated, or 180 days after the initial start-up, whichever date comes first. Each owner or operator shall either: (a) Reduce emissions of TOC (less methane and ethane) by 98 weight-percent, or to a TOC (less methane and ethane) concentration of 20 ppmv, on a...

  19. 40 CFR 63.997 - Performance test and compliance assessment requirements for control devices.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... as TOC minus methane and ethane according to the procedures specified. (i) Selection of sampling... regulated material or TOC, sampling sites shall be located as specified in paragraphs (e)(2)(i)(A)(1) and (e... shall ensure the measurement of total organic regulated material or TOC (minus methane and ethane...

  20. 40 CFR 65.158 - Performance test procedures for control devices.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... regulated material or as TOC (minus methane and ethane) according to the procedures specified. (1) Method 1... material or TOC, sampling sites shall be located at the inlet of the control device as specified in the... sampling sites shall ensure the measurement of total regulated material or TOC (minus methane and ethane...

  1. NOTE: Laboratory Studies of Catalysis of CO to Organics on Grain Analogs

    NASA Astrophysics Data System (ADS)

    Ferrante, R. F.; Moore, M. H.; Nuth, J. A.; Smith, T.

    2000-05-01

    Experiments simulating heterogeneous conversion of H 2 and CO into simple hydrocarbons in astrophysical environments have been performed, utilizing realistic cosmic grain analogs of Fe-doped silicates as Fischer-Tropsch-Type catalysts. Catalysis was studied for temperatures from 470-670 K and reactant gas mixtures of H 2/CO with a ratio of 2-100. The total gas pressure was near 0.5 bar. Maximum conversion rates of a few percentage points were achieved over a 3-h time period. Major products were methane, ethane, ethylene, carbon dioxide, and water. Products were identified by IR spectroscopy.

  2. Rapid and Simple Capillary-Rise/Vanishing Interfacial Tension Method To Determine Crude Oil Minimum Miscibility Pressure: Pure and Mixed CO 2 , Methane, and Ethane

    DOE PAGES

    Hawthorne, Steven B.; Miller, David J.; Jin, Lu; ...

    2016-07-20

    We report here a simplification of the capillary-rise/vanishing interfacial tension (IFT) method to measure minimum miscibility pressure (MMP) based on only requiring knowledge of when the interfacial tension approaches zero. Simply measuring the height of the crude oil in a capillary at several pressures from ambient to near the MMP pressure and extrapolating the oil height versus pressure plot to zero oil height yields the MMP without the need of the additional instrumentation and labor required to perform actual IFT measurements. A total of 2−4 MMP values can be determined per day with only one experimental apparatus, and the methodmore » greatly reduces the initial cost and complexity of the required instrumentation. The use of three capillaries having different inner diameters allows for triplicate determinations of MMP from each experiment. Because the actual MMP pressure need not be reached during the experiment, MMP values that exceed the pressure ratings of the equipment can be reasonably estimated (e.g., MMPs using pure nitrogen). The method was used to determine the MMP pressure for crude oil samples from a conventional Muddy Formation reservoir in the Powder River Basin [American Petroleum Institute (API) gravity of 35.8°] and an unconventional Bakken Formation reservoir in the Williston Basin (API gravity of 38.7°). The method is reproducible [typically <4% relative standard deviation (RSD)], and the method gave good agreement for a “live” Bakken oil with the results from a slim tube test of a commercial laboratory. Approximately 80 MMP values were measured using pure CO2, methane, and ethane as well as 0−100% mole ratios of methane/CO2 and methane/ethane. For both oil samples, ethane MMPs were ca. one-half those with CO2, while methane MMPs were ca. double or triple those with CO2. MMPs with mixed methane/CO2 showed a linear increase with mole percent methane for both crude oils, while both oils showed an exponential increase in MMP with mole percent methane in ethane, with a little increase in MMP until ca. 20 mol % methane in ethane.« less

  3. Self-preservation and structural transition of gas hydrates during dissociation below the ice point: an in situ study using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Zhong, Jin-Rong; Zeng, Xin-Yang; Zhou, Feng-He; Ran, Qi-Dong; Sun, Chang-Yu; Zhong, Rui-Qin; Yang, Lan-Ying; Chen, Guang-Jin; Koh, Carolyn A.

    2016-12-01

    The hydrate structure type and dissociation behavior for pure methane and methane-ethane hydrates at temperatures below the ice point and atmospheric pressure were investigated using in situ Raman spectroscopic analysis. The self-preservation effect of sI methane hydrate is significant at lower temperatures (268.15 to 270.15 K), as determined by the stable C-H region Raman peaks and AL/AS value (Ratio of total peak area corresponding to occupancies of guest molecules in large cavities to small cavities) being around 3.0. However, it was reduced at higher temperatures (271.15 K and 272.15 K), as shown from the dramatic change in Raman spectra and fluctuations in AL/AS values. The self-preservation effect for methane-ethane double hydrate is observed at temperatures lower than 271.15 K. The structure transition from sI to sII occurred during the methane-ethane hydrate decomposition process, which was clearly identified by the shift in peak positions and the change in relative peak intensities at temperatures from 269.15 K to 271.15 K. Further investigation shows that the selectivity for self-preservation of methane over ethane leads to the structure transition; this kind of selectivity increases with decreasing temperature. This work provides new insight into the kinetic behavior of hydrate dissociation below the ice point.

  4. Continuous spectroscopic measurement of methane isotopes and ethane made on board an aircraft: instrument configuration and characterisation

    NASA Astrophysics Data System (ADS)

    Pitt, Joseph; Young, Stuart; Hopkins, James; Lee, James; Bauguitte, Stéphane; Dorsey, James; Allen, Grant; Gallagher, Martin; Yacovitch, Tara; Zahniser, Mark; Fisher, Rebecca; Lowry, Dave; Nisbet, Euan

    2017-04-01

    We describe the configuration of two commercially available absorption spectrometers for use on board the UK Facility for Airborne Atmospheric Research (FAAM) aircraft. A dual laser instrument has been used to make continuous measurements of the atmospheric 13CH4:12CH4 ratio and ethane mole fraction, using an interband cascade laser (ICL) and a recently developed type of diode laser respectively. Simultaneous measurements of atmospheric ethane have also been made using a single laser instrument employing an ICL, enabling instrument inter-comparison. Instrument performance is evaluated over a series of test flights, and initial results from the MOYA (Methane Observations and Yearly Assessments) campaign, targeting biomass burning plumes in west Africa, are also presented. We describe the calibration procedure and data analysis approaches for methane isotope measurement, involving calibration over a range of methane isotopic composition and methane mole fraction. We assess the effectiveness of this calibration technique during the first MOYA campaign period using measurements of a target cylinder of known composition.

  5. Irradiation Products On Dwarf Planet Makemake

    NASA Astrophysics Data System (ADS)

    Brown, M. E.; Schaller, E. L.; Blake, G. A.

    2015-03-01

    The dark, reddish tinged surfaces of icy bodies in the outer solar system are usually attributed to the long term irradiation of simple hydrocarbons leading to the breaking of C-H bonds, loss of hydrogen, and the production of long carbon chains. While the simple hydrocarbon methane is stable and detected on the most massive bodies in the Kuiper Belt, evidence of active irradiation chemistry is scant except for the presence of ethane on methane-rich Makemake and the possible detections of ethane on more methane-poor Pluto and Quaoar. We have obtained deep high signal-to-noise spectra of Makemake from 1.4 to 2.5 μm in an attempt to trace the radiation chemistry in the outer solar system beyond the initial ethane formation. We present the first astrophysical detection of solid ethylene and evidence for acetylene and high-mass alkanes—all expected products of the continued irradiation of methane, and use these species to map the chemical pathway from methane to long-chain hydrocarbons.

  6. 40 CFR 60.700 - Applicability and designation of affected facility.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... compounds (TOC) (less methane and ethane) in the vent stream less than 300 ppmv as measured by Method 18 or... maximum production rate at which the affected facility will be operated, or 180 days after the initial... limits in these standards are expressed in terms of TOC, measured as TOC less methane and ethane. This...

  7. 40 CFR 60.700 - Applicability and designation of affected facility.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... compounds (TOC) (less methane and ethane) in the vent stream less than 300 ppmv as measured by Method 18 or... maximum production rate at which the affected facility will be operated, or 180 days after the initial... limits in these standards are expressed in terms of TOC, measured as TOC less methane and ethane. This...

  8. Improvement of gas hydrate preservation by increasing compression pressure to simple hydrates of methane, ethane, and propane

    NASA Astrophysics Data System (ADS)

    Kida, Masato; Jin, Yusuke; Watanabe, Mizuho; Murayama, Tetsuro; Nagao, Jiro

    2017-09-01

    In this report, we describe the dissociation behavior of gas hydrate grains pressed at 1 and 6 MPa. Certain simple gas hydrates in powder form show anomalous preservation phenomenon under their thermodynamic unstable condition. Investigation of simple hydrates of methane, ethane, and propane reveals that high pressure applied to the gas hydrate particles enhances their preservation effects. Application of high pressure increases the dissociation temperature of methane hydrate and has a restrictive effect against the dissociation of ethane and propane hydrate grains. These improvements of gas hydrate preservation by increasing pressure to the initial gas hydrate particles imply that appropriate pressure applied to gas hydrate particles enhances gas hydrate preservation effects.

  9. Application of Gauss's theorem to quantify localized surface emissions from airborne measurements of wind and trace gases

    DOE PAGES

    Conley, Stephen; Faloona, Ian; Mehrotra, Shobhit; ...

    2017-09-13

    Airborne estimates of greenhouse gas emissions are becoming more prevalent with the advent of rapid commercial development of trace gas instrumentation featuring increased measurement accuracy, precision, and frequency, and the swelling interest in the verification of current emission inventories. Multiple airborne studies have indicated that emission inventories may underestimate some hydrocarbon emission sources in US oil- and gas-producing basins. Consequently, a proper assessment of the accuracy of these airborne methods is crucial to interpreting the meaning of such discrepancies. We present a new method of sampling surface sources of any trace gas for which fast and precise measurements can be mademore » and apply it to methane, ethane, and carbon dioxide on spatial scales of ~1000 m, where consecutive loops are flown around a targeted source region at multiple altitudes. Using Reynolds decomposition for the scalar concentrations, along with Gauss's theorem, we show that the method accurately accounts for the smaller-scale turbulent dispersion of the local plume, which is often ignored in other average mass balance methods. With the help of large eddy simulations (LES) we further show how the circling radius can be optimized for the micrometeorological conditions encountered during any flight. Furthermore, by sampling controlled releases of methane and ethane on the ground we can ascertain that the accuracy of the method, in appropriate meteorological conditions, is often better than 10 %, with limits of detection below 5 kg h -1 for both methane and ethane. Because of the FAA-mandated minimum flight safe altitude of 150 m, placement of the aircraft is critical to preventing a large portion of the emission plume from flowing underneath the lowest aircraft sampling altitude, which is generally the leading source of uncertainty in these measurements. Finally, we show how the accuracy of the method is strongly dependent on the number of sampling loops and/or time spent sampling the source plume.« less

  10. Application of Gauss's theorem to quantify localized surface emissions from airborne measurements of wind and trace gases

    NASA Astrophysics Data System (ADS)

    Conley, Stephen; Faloona, Ian; Mehrotra, Shobhit; Suard, Maxime; Lenschow, Donald H.; Sweeney, Colm; Herndon, Scott; Schwietzke, Stefan; Pétron, Gabrielle; Pifer, Justin; Kort, Eric A.; Schnell, Russell

    2017-09-01

    Airborne estimates of greenhouse gas emissions are becoming more prevalent with the advent of rapid commercial development of trace gas instrumentation featuring increased measurement accuracy, precision, and frequency, and the swelling interest in the verification of current emission inventories. Multiple airborne studies have indicated that emission inventories may underestimate some hydrocarbon emission sources in US oil- and gas-producing basins. Consequently, a proper assessment of the accuracy of these airborne methods is crucial to interpreting the meaning of such discrepancies. We present a new method of sampling surface sources of any trace gas for which fast and precise measurements can be made and apply it to methane, ethane, and carbon dioxide on spatial scales of ˜ 1000 m, where consecutive loops are flown around a targeted source region at multiple altitudes. Using Reynolds decomposition for the scalar concentrations, along with Gauss's theorem, we show that the method accurately accounts for the smaller-scale turbulent dispersion of the local plume, which is often ignored in other average mass balance methods. With the help of large eddy simulations (LES) we further show how the circling radius can be optimized for the micrometeorological conditions encountered during any flight. Furthermore, by sampling controlled releases of methane and ethane on the ground we can ascertain that the accuracy of the method, in appropriate meteorological conditions, is often better than 10 %, with limits of detection below 5 kg h-1 for both methane and ethane. Because of the FAA-mandated minimum flight safe altitude of 150 m, placement of the aircraft is critical to preventing a large portion of the emission plume from flowing underneath the lowest aircraft sampling altitude, which is generally the leading source of uncertainty in these measurements. Finally, we show how the accuracy of the method is strongly dependent on the number of sampling loops and/or time spent sampling the source plume.

  11. Application of Gauss's theorem to quantify localized surface emissions from airborne measurements of wind and trace gases

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

    Conley, Stephen; Faloona, Ian; Mehrotra, Shobhit

    Airborne estimates of greenhouse gas emissions are becoming more prevalent with the advent of rapid commercial development of trace gas instrumentation featuring increased measurement accuracy, precision, and frequency, and the swelling interest in the verification of current emission inventories. Multiple airborne studies have indicated that emission inventories may underestimate some hydrocarbon emission sources in US oil- and gas-producing basins. Consequently, a proper assessment of the accuracy of these airborne methods is crucial to interpreting the meaning of such discrepancies. We present a new method of sampling surface sources of any trace gas for which fast and precise measurements can be mademore » and apply it to methane, ethane, and carbon dioxide on spatial scales of ~1000 m, where consecutive loops are flown around a targeted source region at multiple altitudes. Using Reynolds decomposition for the scalar concentrations, along with Gauss's theorem, we show that the method accurately accounts for the smaller-scale turbulent dispersion of the local plume, which is often ignored in other average mass balance methods. With the help of large eddy simulations (LES) we further show how the circling radius can be optimized for the micrometeorological conditions encountered during any flight. Furthermore, by sampling controlled releases of methane and ethane on the ground we can ascertain that the accuracy of the method, in appropriate meteorological conditions, is often better than 10 %, with limits of detection below 5 kg h -1 for both methane and ethane. Because of the FAA-mandated minimum flight safe altitude of 150 m, placement of the aircraft is critical to preventing a large portion of the emission plume from flowing underneath the lowest aircraft sampling altitude, which is generally the leading source of uncertainty in these measurements. Finally, we show how the accuracy of the method is strongly dependent on the number of sampling loops and/or time spent sampling the source plume.« less

  12. Thermodynamic equilibrium calculations of dimethyl ether steam reforming and dimethyl ether hydrolysis

    NASA Astrophysics Data System (ADS)

    Semelsberger, Troy A.; Borup, Rodney L.

    The production of a hydrogen-rich fuel-cell feed by dimethyl ether (DME) steam reforming was investigated using calculations of thermodynamic equilibrium as a function of steam-to-carbon ratio (0.00-4.00), temperature (100-600 °C), pressure (1-5 atm), and product species. Species considered were acetone, acetylene, carbon dioxide, carbon monoxide, dimethyl ether, ethane, ethanol, ethylene, formaldehyde, formic acid, hydrogen, isopropanol, methane, methanol, methyl-ethyl ether, n-propanol and water. Thermodynamic equilibrium calculations of DME steam reforming indicate complete conversion of dimethyl ether to hydrogen, carbon monoxide and carbon dioxide at temperatures greater than 200 °C and steam-to-carbon ratios greater than 1.25 at atmospheric pressure ( P = 1 atm). Increasing the operating pressure shifts the equilibrium toward the reactants; increasing the pressure from 1 to 5 atm decreases the conversion of dimethyl ether from 99.5 to 76.2%. The trend of thermodynamically stable products in decreasing mole fraction is methane, ethane, isopropyl alcohol, acetone, n-propanol, ethylene, ethanol, methyl-ethyl ether and methanol-formaldehyde, formic acid, and acetylene were not observed. Based on the equilibrium calculations, the optimal processing conditions for dimethyl ether steam reforming occur at a steam-to-carbon ratio of 1.50, a pressure of 1 atm, and a temperature of 200 °C. These thermodynamic equilibrium calculations show dimethyl ether processed with steam will produce hydrogen-rich fuel-cell feeds—with hydrogen concentrations exceeding 70%. The conversion of dimethyl ether via hydrolysis (considering methanol as the only product) is limited by thermodynamic equilibrium. Equilibrium conversion increases with temperature and steam-to-carbon ratio. A maximum dimethyl ether conversion of 62% is achieved at a steam-to-carbon ratio of 5.00 and a processing temperature of 600 °C.

  13. Fugitive Emissions Attribution via Simultaneous Measurement of Ethane and Methane Isotopic Signature in Vehicle-based Surveys

    NASA Astrophysics Data System (ADS)

    Marshall, A. D.; Williams, J. P.; Baillie, J.; MacKay, K.; Risk, D. A.; Fleck, D.

    2016-12-01

    Detecting and attributing sub-regulatory fugitive emissions in the energy sector remains a priority for industry and environmental groups alike. Vehicle-based geochemical emission detection and attribution is seeing increasingly widespread use. In order to distinguish between biogenic and thermogenic emission sources, these techniques rely on tracer species like δ13C of methane (δ13CH4). In this study, we assessed the performance of the new Picarro G2210-i, a cavity ring-down spectroscopy (CRDS) analyzer that measures δ13CH4 and ethane (C2H6) simultaneously to provide increased thermogenic tracer power. In the lab, we assessed drift and other performance characteristics relative to a G2201-i (existing isotopic CH4 and carbon dioxide analyzer). We performed model experiments to synthetically assess the new analyzer's utility for oil and gas developments with differing levels of ethane. Lastly, we also conducted survey drives in a high-ethane oilfield using both the G2210-i and G2201-i. Results were very positive. The G2210-i showed minimal drift, as expected. Allan deviation experiments showed that the G2210-i has a precision of 0.482 ppb for CH4 and 3.15 ppb for C2H6 for 1Hz measurements. Computational experiments confirmed that the resolution of C2H6 is sufficient for detecting and attributing thermogenic CH4 at distance in oil and gas settings, which was further validated in the field where we measured simultaneous departures in δ13CH4 and C2H6 within plumes from venting infrastructure. C2:C1 ratios also proved very useful for attribution. As we move to reduce emissions from the energy industry, this analyzer presents new analytical possibilities that will be of high value to industry stakeholders.

  14. 40 CFR 63.1426 - Process vent requirements for determining organic HAP concentration, control efficiency, and...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... percent reduction may be measured as total epoxide, total organic HAP, or as TOC minus methane and ethane... TOC (minus methane and ethane) concentrations in all process vent streams and primary and secondary... million by volume total epoxide or TOC limit in § 63.1425(b)(1)(ii) or (b)(2)(iii), the sampling site...

  15. 40 CFR 60.700 - Applicability and designation of affected facility.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... compounds (TOC) (less methane and ethane) in the vent stream less than 300 ppmv as measured by Method 18 or a concentration of TOC in the vent stream less than 150 ppmv as measured by Method 25A is exempt... limits in these standards are expressed in terms of TOC, measured as TOC less methane and ethane. This...

  16. Titan's missing ethane: From the atmosphere to the subsurface

    NASA Astrophysics Data System (ADS)

    Gilliam, Ashley E.; Lerman, Abraham

    2016-09-01

    The second most abundant component of the present-day Titan atmosphere, methane (CH4), is known to undergo photolytic conversion to ethane (C2H6) that accumulates as a liquid on Titan's surface. Condensation temperature of ethane is higher than that of methane, so that ethane "rain" may be expected to occur before the liquefaction of methane. At present, the partial pressure of ethane in the atmosphere is 1E-5 bar, much lower than 1E-1 bar of CH4. Estimated 8.46E17 kg or 1.37E6 km3 of C2H6 have been produced on Titan since accretion. The Titan surface reservoirs of ethane are lakes and craters, of estimated volume of 50,000 km3 and 61,000 km3, respectively. As these are smaller than the total volume of liquid ethane produced in the course of Titan's history, the excess may be stored in the subsurface of the crust, made primarily of water ice. The minimum porosity of the crust needed to accommodate all the liquid ethane would be only 0.9% of the uppermost 2 km of the crust. The occurrence of CH4 and liquid C2H6 on Titan has led to much speculation on the possibility of life on that satellite. The aggregation of organic molecules in a "primordial soup or bullion" depends in part on the viscosity of the medium, diffusivity of organic molecules in it, and rates of polymerization reactions. The temperatures on Titan, much lower than on primordial Earth, are less favorable to the "Second Coming of life" on Titan.

  17. In situ high temperature MAS NMR study of the mechanisms of catalysis. Ethane aromatization on Zn-modified zeolite BEA.

    PubMed

    Arzumanov, Sergei S; Gabrienko, Anton A; Freude, Dieter; Stepanov, Alexander G

    2009-04-01

    Ethane conversion into aromatic hydrocarbons over Zn-modified zeolite BEA has been analyzed by high-temperature MAS NMR spectroscopy. Information about intermediates (Zn-ethyl species) and reaction products (mainly toluene and methane), which were formed under the conditions of a batch reactor, was obtained by (13)C MAS NMR. Kinetics of the reaction, which was monitored by (1)H MAS NMR in situ at the temperature of 573K, provided information about the reaction mechanism. Simulation of the experimental kinetics within the frames of the possible kinetic schemes of the reaction demonstrates that a large amount of methane evolved under ethane aromatization arises from the stage of direct ethane hydrogenolysis.

  18. Self-preservation and structural transition of gas hydrates during dissociation below the ice point: an in situ study using Raman spectroscopy

    PubMed Central

    Zhong, Jin-Rong; Zeng, Xin-Yang; Zhou, Feng-He; Ran, Qi-Dong; Sun, Chang-Yu; Zhong, Rui-Qin; Yang, Lan-Ying; Chen, Guang-Jin; Koh, Carolyn A.

    2016-01-01

    The hydrate structure type and dissociation behavior for pure methane and methane-ethane hydrates at temperatures below the ice point and atmospheric pressure were investigated using in situ Raman spectroscopic analysis. The self-preservation effect of sI methane hydrate is significant at lower temperatures (268.15 to 270.15 K), as determined by the stable C-H region Raman peaks and AL/AS value (Ratio of total peak area corresponding to occupancies of guest molecules in large cavities to small cavities) being around 3.0. However, it was reduced at higher temperatures (271.15 K and 272.15 K), as shown from the dramatic change in Raman spectra and fluctuations in AL/AS values. The self-preservation effect for methane-ethane double hydrate is observed at temperatures lower than 271.15 K. The structure transition from sI to sII occurred during the methane-ethane hydrate decomposition process, which was clearly identified by the shift in peak positions and the change in relative peak intensities at temperatures from 269.15 K to 271.15 K. Further investigation shows that the selectivity for self-preservation of methane over ethane leads to the structure transition; this kind of selectivity increases with decreasing temperature. This work provides new insight into the kinetic behavior of hydrate dissociation below the ice point. PMID:27941857

  19. Self-preservation and structural transition of gas hydrates during dissociation below the ice point: an in situ study using Raman spectroscopy.

    PubMed

    Zhong, Jin-Rong; Zeng, Xin-Yang; Zhou, Feng-He; Ran, Qi-Dong; Sun, Chang-Yu; Zhong, Rui-Qin; Yang, Lan-Ying; Chen, Guang-Jin; Koh, Carolyn A

    2016-12-12

    The hydrate structure type and dissociation behavior for pure methane and methane-ethane hydrates at temperatures below the ice point and atmospheric pressure were investigated using in situ Raman spectroscopic analysis. The self-preservation effect of sI methane hydrate is significant at lower temperatures (268.15 to 270.15 K), as determined by the stable C-H region Raman peaks and A L /A S value (Ratio of total peak area corresponding to occupancies of guest molecules in large cavities to small cavities) being around 3.0. However, it was reduced at higher temperatures (271.15 K and 272.15 K), as shown from the dramatic change in Raman spectra and fluctuations in A L /A S values. The self-preservation effect for methane-ethane double hydrate is observed at temperatures lower than 271.15 K. The structure transition from sI to sII occurred during the methane-ethane hydrate decomposition process, which was clearly identified by the shift in peak positions and the change in relative peak intensities at temperatures from 269.15 K to 271.15 K. Further investigation shows that the selectivity for self-preservation of methane over ethane leads to the structure transition; this kind of selectivity increases with decreasing temperature. This work provides new insight into the kinetic behavior of hydrate dissociation below the ice point.

  20. Cryogenic Gellant and Fuel Formulation for Metallized Gelled Propellants: Hydrocarbons and Hydrogen with Aluminum

    NASA Technical Reports Server (NTRS)

    Wong, Wing; Starkovich, John; Adams, Scott; Palaszewski, Bryan; Davison, William; Burt, William; Thridandam, Hareesh; Hu-Peng, Hsiao; Santy, Myrrl J.

    1994-01-01

    An experimental program to determine the viability of nanoparticulate gellant materials for gelled hydrocarbons and gelled liquid hydrogen was conducted. The gellants included alkoxides (BTMSE and BTMSH) and silica-based materials. Hexane, ethane, propane and hydrogen were gelled with the newly-formulated materials and their rheological properties were determined: shear stress versus shear rate and their attendant viscosities. Metallized hexane with aluminum particles was also rheologically characterized. The propellant and gellant formulations were selected for the very high surface area and relatively-high energy content of the gellants. These new gellants can therefore improve rocket engine specific impulse over that obtained with traditional cryogenic-fuel gellant materials silicon dioxide, frozen methane, or frozen ethane particles. Significant reductions in the total mass of the gellant were enabled in the fuels. In gelled liquid hydrogen, the total mass of gellant was reduced from 10-40 wt percent of frozen hydrocarbon particles to less that 8 wt percent with the alkoxide.

  1. Elastic wave speeds and moduli in polycrystalline ice Ih, si methane hydrate, and sll methane-ethane hydrate

    USGS Publications Warehouse

    Helgerud, M.B.; Waite, W.F.; Kirby, S.H.; Nur, A.

    2009-01-01

    We used ultrasonic pulse transmission to measure compressional, P, and shear, S, wave speeds in laboratory-formed polycrystalline ice Ih, si methane hydrate, and sll methane-ethane hydrate. From the wave speed's linear dependence on temperature and pressure and from the sample's calculated density, we derived expressions for bulk, shear, and compressional wave moduli and Poisson's ratio from -20 to 15??C and 22.4 to 32.8 MPa for ice Ih, -20 to 15??C and 30.5 to 97.7 MPa for si methane hydrate, and -20 to 10??C and 30.5 to 91.6 MPa for sll methane-ethane hydrate. All three materials had comparable P and S wave speeds and decreasing shear wave speeds with increasing applied pressure. Each material also showed evidence of rapid intergranular bonding, with a corresponding increase in wave speed, in response to pauses in sample deformation. There were also key differences. Resistance to uniaxial compaction, indicated by the pressure required to compact initially porous samples, was significantly lower for ice Ih than for either hydrate. The ice Ih shear modulus decreased with increasing pressure, in contrast to the increase measured in both hydrates ?? 2009.

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

    Yuan Zhang; Jin-hu Wu; Dong-ke Zhang

    The cracking of oil refinery off-gas, simulated with a gas mixture containing methane (51%), ethylene (21.4%), ethane (21.1%), and propane (6.5%), over a coal char, petroleum coke, and quartz, respectively, has been studied in a fixed bed reactor. The experiments were performed at temperatures between 850 and 1000{sup o}C and at atmospheric pressure. The results show that the conversions of all species considered increased with increasing temperature. Ethane and propane completely decomposed over all three bed materials in the temperature range investigated. However, the higher initial conversion rates of methane and ethylene cracking at all temperatures were observed only overmore » the coal char and not on the petroleum coke and quartz, indicating a significant catalytic effect of the coal char on methane and ethylene cracking. Methane and ethylene conversions decreased with reaction time due to deactivation of the coal char by carbon deposition on the char surface and, in the later stage of a cracking experiment, became negative, suggesting that methane and ethylene had been formed during the cracking of ethane and propane. 16 refs., 13 figs., 2 tabs.« less

  3. 40 CFR 63.2535 - What compliance options do I have if part of my plant is subject to both this subpart and another...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... compliance, you must consider all total organic compounds, minus methane and ethane, in such equipment for... total organic compounds, minus methane and ethane, in such equipment for purposes of compliance with... greatest production on a mass basis over the 5-year period specified in paragraph (l)(1)(ii) of this...

  4. 40 CFR 63.2535 - What compliance options do I have if part of my plant is subject to both this subpart and another...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... compliance, you must consider all total organic compounds, minus methane and ethane, in such equipment for... total organic compounds, minus methane and ethane, in such equipment for purposes of compliance with... greatest production on a mass basis over the 5-year period specified in paragraph (l)(1)(ii) of this...

  5. 40 CFR 63.7941 - How do I conduct a performance test, design evaluation, or other type of initial compliance...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... vent; Ei, Eo = Mass rate of total organic compounds (TOC) (minus methane and ethane) or total HAP, from... reduction for all affected process vents, percent Ei = Mass rate of TOC (minus methane and ethane) or total... uncontrolled vents, as calculated in this section, kilograms TOC per hour or kilograms HAP per hour; Eo = Mass...

  6. Process for the preparation of methane and/or ethane

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

    Wagstaff, N.

    1981-09-22

    According to Shell, methane and ethane can be produced from a C/sub 2/-C/sub 4/ paraffin feed stream (such as the by-product of mineral-oil production) by contacting the stream with certain crystalline silicates at temperatures of 800/sup 0/-1200/sup 0/F and 145 psi pressure. The crystalline silicates must be specially prepared to obtain the required characteristics.

  7. Low-Temperature and Rapid Growth of Large Single-Crystalline Graphene with Ethane.

    PubMed

    Sun, Xiao; Lin, Li; Sun, Luzhao; Zhang, Jincan; Rui, Dingran; Li, Jiayu; Wang, Mingzhan; Tan, Congwei; Kang, Ning; Wei, Di; Xu, H Q; Peng, Hailin; Liu, Zhongfan

    2018-01-01

    Future applications of graphene rely highly on the production of large-area high-quality graphene, especially large single-crystalline graphene, due to the reduction of defects caused by grain boundaries. However, current large single-crystalline graphene growing methodologies are suffering from low growth rate and as a result, industrial graphene production is always confronted by high energy consumption, which is primarily caused by high growth temperature and long growth time. Herein, a new growth condition achieved via ethane being the carbon feedstock to achieve low-temperature yet rapid growth of large single-crystalline graphene is reported. Ethane condition gives a growth rate about four times faster than methane, achieving about 420 µm min -1 for the growth of sub-centimeter graphene single crystals at temperature about 1000 °C. In addition, the temperature threshold to obtain graphene using ethane can be reduced to 750 °C, lower than the general growth temperature threshold (about 1000 °C) with methane on copper foil. Meanwhile ethane always keeps higher graphene growth rate than methane under the same growth temperature. This study demonstrates that ethane is indeed a potential carbon source for efficient growth of large single-crystalline graphene, thus paves the way for graphene in high-end electronical and optoelectronical applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. High-Precision Measurement of 13C/12C Isotopic Ratio Using Gas Chromatography-Combustion-Cavity Ring-Down Spectroscopy

    NASA Astrophysics Data System (ADS)

    Saad, N.; Kuramoto, D. S.; Haase, C.; Crosson, E.; Tan, S.; Zare, R. N.

    2009-12-01

    Light stable isotope analysis, and in particular, compound specific isotopic analysis (CSIA), is a valuable tool to elucidate pathways and provide a better insight into biological, ecological, and geological systems. We present here the results of compound-specific isotopic carbon analysis of short chain hydrocarbons using the world’s first combination of gas chromatography, combustion interface, and cavity ring-down spectroscopy (GC-C-CRDS). Cavity ring-down spectroscopy (CRDS) is a highly sensitive optical spectroscopy, one application of which is to measure the stable isotopic ratios in small molecules. Because it uses a highly reflective optical cavity with many kilometers effective path length, CRDS provides some of the most sensitive and precise optical absorption measurements. Most optical spectroscopy isotopic analysis measures the quantities of each isotopologue independently using their distinct ro-vibrational spectra. The most common isotopes measured with optical spectroscopy are 13C and 12C in carbon dioxide. However, the isotopes of hydrogen, oxygen, and sulfur have also been measured. Unlike isotope ratio mass spectrometry (IRMS), optical spectroscopy can distinguish among isobars, which have essentially identical m/z ratios. The combination of chemical separation, chemical conversion, and CRDS makes a nearly universal tool for isotopic analysis of mixtures. In addition, CRDS can tolerate a variety of compounds mixed with the target. For example, CRDS can measure carbon dioxide and its isotopic 13C/12C ratio in the presence of oxygen. Using the novel GC-C-CRDS system, we injected a 75-microliter mixture of approximately equal quantities of methane, ethane, and propane into a gas chromatograph using helium as carrier gas. The methane, ethane, and propane were separated in time by 100 to 200 seconds after the chromatograph. Oxygen gas was added, and the hydrocarbons were combusted in a catalytic combustor with platinum and nickel, held at 1150oC. The combusted products were combined with dry nitrogen gas to provide sufficient gas flow for the CRDS analyzer, which measured the 13C/12C isotopic ratio of the separated methane, ethane, and propane, obtaining a precision of 0.95 permil or better. The calibration accuracy was within 3 permil of the values determined using IRMS. The current CRDS-based system is less expensive, does not require highly trained personnel to operate, and is portable, compared with IRMS. We anticipate that advances in spectroscopic analysis will improve the precision and accuracy of the CRDS isotopic measurement, making it comparable with IRMS.

  9. Fugitive Methane Emission Identification and Source Attribution: Ethane-to-Methane Analysis Using a Portable Cavity Ring-Down Spectroscopy Analyzer

    NASA Astrophysics Data System (ADS)

    Kim-Hak, D.; Fleck, D.

    2017-12-01

    Natural gas analysis and methane specifically have become increasingly important by virtue of methane's 28-36x greenhouse warming potential compared to CO2 and accounting for 10% of total greenhouse gas emissions in the US alone. Additionally, large uncontrolled leaks, such as the recent one from Aliso Canyon in Southern California, originating from uncapped wells, storage facilities and coal mines have increased the total global contribution of methane missions even further. Determining the specific fingerprint of methane sources by quantifying the ethane to methane (C2:C1) ratios provides us with means to understand processes yielding methane and allows for sources of methane to be mapped and classified through these processes; i.e. biogenic or thermogenic, oil vs. gas vs. coal gas-related. Here we present data obtained using a portable cavity ring-down spectrometry analyzer weighing less than 25 lbs and consuming less than 35W that simultaneously measures methane and ethane in real-time with a raw 1-σ precision of <30 ppb and <10 ppb, respectively at <1 Hz. These precisions allow for a C2:C1 ratio 1-σ measurement of <0.1% above 10 ppm in a single measurement. Furthermore, a high precision methane only mode is available for surveying and locating leakage with a 1-σ precision of <3 ppb. Source discrimination data of local leaks and methane sources using this analysis method are presented. Additionally, two-dimensional plume snapshots are constructed using an integrated onboard GPS in order to visualize horizontal plane gas propagation.

  10. Measurements of ethane in Antarctic ice cores

    NASA Astrophysics Data System (ADS)

    Verhulst, K. R.; Fosse, E. K.; Aydin, K. M.; Saltzman, E. S.

    2011-12-01

    Ethane is one of the most abundant hydrocarbons in the atmosphere. The major ethane sources are fossil fuel production and use, biofuel combustion, and biomass-burning emissions and the primary loss pathway is via reaction with OH. A paleoatmospheric ethane record would be useful as a tracer of biomass-burning emissions, providing a constraint on past changes in atmospheric methane and methane isotopes. An independent biomass-burning tracer would improve our understanding of the relationship between biomass burning and climate. The mean annual atmospheric ethane level at high southern latitudes is about 230 parts per trillion (ppt), and Antarctic firn air measurements suggest that atmospheric ethane levels in the early 20th century were considerably lower (Aydin et al., 2011). In this study, we present preliminary measurements of ethane (C2H6) in Antarctic ice core samples with gas ages ranging from 0-1900 C.E. Samples were obtained from dry-drilled ice cores from South Pole and Vostok in East Antarctica, and from the West Antarctic Ice Sheet Divide (WAIS-D). Gases were extracted from the ice by melting under vacuum in a glass vessel sealed by indium wire and were analyzed using high resolution GC/MS with isotope dilution. Ethane levels measured in ice core samples were in the range 100-220 ppt, with a mean of 157 ± 45 ppt (n=12). System blanks contribute roughly half the amount of ethane extracted from a 300 g ice core sample. These preliminary data exhibit a temporal trend, with higher ethane levels from 0-900 C.E., followed by a decline, reaching a minimum between 1600-1700 C.E. These trends are consistent with variations in ice core methane isotopes and carbon monoxide isotopes (Ferretti et al., 2005, Wang et al., 2010), which indicate changes in biomass burning emissions over this time period. These preliminary data suggest that Antarctic ice core bubbles contain paleoatmospheric ethane levels. With further improvement of laboratory techniques it appears likely that a paleoatmospheric ethane record can be obtained from polar ice cores.

  11. New observations and insights into the morphology and growth kinetics of hydrate films.

    PubMed

    Li, Sheng-Li; Sun, Chang-Yu; Liu, Bei; Li, Zhi-Yun; Chen, Guang-Jin; Sum, Amadeu K

    2014-02-19

    The kinetics of film growth of hydrates of methane, ethane, and methane-ethane mixtures were studied by exposing a single gas bubble to water. The morphologies, lateral growth rates, and thicknesses of the hydrate films were measured for various gas compositions and degrees of subcooling. A variety of hydrate film textures was revealed. The kinetics of two-dimensional film growth was inferred from the lateral growth rate and initial thickness of the hydrate film. A clear relationship between the morphology and film growth kinetics was observed. The shape of the hydrate crystals was found to favour heat or mass transfer and favour further growth of the hydrate film. The quantitative results on the kinetics of film growth showed that for a given degree of subcooling, the initial film thicknesses of the double hydrates were larger than that of pure methane or ethane hydrate, whereas the thickest hydrate film and the lowest lateral growth rate occurred when the methane mole fraction was approximately 0.6.

  12. New Observations and Insights into the Morphology and Growth Kinetics of Hydrate Films

    PubMed Central

    Li, Sheng-Li; Sun, Chang-Yu; Liu, Bei; Li, Zhi-Yun; Chen, Guang-Jin; Sum, Amadeu K.

    2014-01-01

    The kinetics of film growth of hydrates of methane, ethane, and methane-ethane mixtures were studied by exposing a single gas bubble to water. The morphologies, lateral growth rates, and thicknesses of the hydrate films were measured for various gas compositions and degrees of subcooling. A variety of hydrate film textures was revealed. The kinetics of two-dimensional film growth was inferred from the lateral growth rate and initial thickness of the hydrate film. A clear relationship between the morphology and film growth kinetics was observed. The shape of the hydrate crystals was found to favour heat or mass transfer and favour further growth of the hydrate film. The quantitative results on the kinetics of film growth showed that for a given degree of subcooling, the initial film thicknesses of the double hydrates were larger than that of pure methane or ethane hydrate, whereas the thickest hydrate film and the lowest lateral growth rate occurred when the methane mole fraction was approximately 0.6. PMID:24549241

  13. Stratospheric ethane on Neptune - Comparison of groundbased and Voyager IRIS retrievals

    NASA Technical Reports Server (NTRS)

    Kostiuk, Theodor; Romani, Paul; Espenak, Fred; Bezard, Bruno

    1992-01-01

    Near-simultaneous ground and spacecraft measurements of 12-micron ethane emission spectra during the Voyager encounter with Neptune have furnished bases for the determination of stratospheric ethane abundance and the testing and constraining of Neptune methane-photochemistry models. The ethane retrievals were sensitive to the thermal profile used. Contribution functions for warm thermal profiles peaked at higher altitudes, as expected, with the heterodyne functions covering lower-pressure regions. Both constant- and nonconstant-with-height profiles remain candidate distributions for Neptune's stratospheric ethane.

  14. Bacterial ethane formation from reduced, ethylated sulfur compounds in anoxic sediments

    USGS Publications Warehouse

    Oremland, R.S.; Whiticar, Michael J.; Strohmaier, F.E.; Kiene, R.P.

    1988-01-01

    Trace levels of ethane were produced biologically in anoxic sediment slurries from five chemically different aquatic environments. Gases from these locations displayed biogenic characteristics, having 12C-enriched values of ??13CH4 (-62 to -86%.), ??13C2H6 (-35 to -55%.) and high ratios (720 to 140,000) of CH4 [C2H6 + C3H8]. Endogenous production of ethane by slurries was inhibited by autoclaving or by addition of the inhibitor of methanogenic bacteria, 2-bromoethanesulfonic acid (BES). Ethane formation was stimulated markedly by ethanethiol (ESH), and, to a lesser extent, by diethylsulfide (DES). Formation of methane and ethane in ESH- or DES-amended slurries was blocked by BES. Experiments showed that ethionine (or an analogous compound) could be a precursor of ESH. Ethylamine or ethanol additions to slurries caused only a minor stimulation of ethane formation. Similarly, propanethiol additions resulted in only a minor enhancement of propane formation. Cell suspensions of a methyltrophic methanogen produced traces of ethane when incubated in the presence of DES, although the organism did not grow on this compound. These results indicate that methanogenic bacteria produce ethane from the traces of ethylated sulfur compounds present in recent sediments. Preliminary estimates of stable carbon isotope fractionation associated with sediment methane formation from dimethylsulfide was about 40%., while ethane formation from DES and ESH was only 4. 6 and 6.5%., respectively. ?? 1988.

  15. Titan's Carbon Isotopic Ratio: A Clue To Atmospheric Evolution?

    NASA Astrophysics Data System (ADS)

    Nixon, C. A.; Jennings, D. E.; Romani, P. N.; Jolly, A.; Teanby, N. A.; Irwin, P. G.; Bézard, B.; Vinatier, S.; Coustenis, A.; Flasar, F. M.

    2009-12-01

    In this presentation we describe the latest results to come from Cassini CIRS and ground-based telescopic measurements of Titan's 12C/13C ratio in atmospheric molecules, focusing on hydrocarbons. Previously, the Huygens GCMS instrument measured 12CH4/13CH4 to be 82±1 (Niemann et al., Nature, 438, 779-784, 2005), substantially and significantly lower than the VPDB inorganic Earth standard of 89.4. It is also at odds with measurements for the giant planets. Cassini CIRS infrared spectra have confirmed this enhancement in 13CH4, but also revealed that the ratio in ethane, the major photochemical product of methane photolysis, does not appear enhanced (90±7) (Nixon et al.. Icarus, 195, 778-791, 2008) and is compatible with the terrestrial and combined giant planet value (88±7, Sada et al., Ap. J., 472, p. 903-907, 1996). Recently-published results from spectroscopy using the McMath-Pierce telescope at Kitt Pitt (Jennings et al., JCP, 2009, in press) have confirmed this deviation between methane and ethane, and an explanation has been proposed. This invokes a kinetic isotope effect (KIE) in the abstraction of methane by ethynyl, a major ethane formation pathway, to preferentially partition 12C into ethane and leave an enhancement in atmospheric 13CH4 relative to the incoming flux from the reservoir. Modeling shows that a steady-state solution exists where the 12C/13C methane is decreased from the reservoir value by exactly the KIE factor (the ratio of 12CH4 to 13CH4 abstraction reaction rates): which is plausibly around 1.08, very close to the observed amount. However, a second solution exists in which we are observing Titan about ~1 methane lifetime after a major injection of methane into the atmosphere which is rapidly being eliminated. Updated measurements by Cassini CIRS of both the methane and ethane 12C/13C ratios will be presented, along with progress in interpreting this ratio. In addition, we summarize the 12C/13C measurements by CIRS in multiple other Titan hydrocarbons, and announce the first measurement of 13C-diacetylene (13C12C3H4) in Titan's atmosphere.

  16. Discrepancy between simulated and observed ethane and propane levels explained by underestimated fossil emissions

    NASA Astrophysics Data System (ADS)

    Dalsøren, Stig B.; Myhre, Gunnar; Hodnebrog, Øivind; Myhre, Cathrine Lund; Stohl, Andreas; Pisso, Ignacio; Schwietzke, Stefan; Höglund-Isaksson, Lena; Helmig, Detlev; Reimann, Stefan; Sauvage, Stéphane; Schmidbauer, Norbert; Read, Katie A.; Carpenter, Lucy J.; Lewis, Alastair C.; Punjabi, Shalini; Wallasch, Markus

    2018-03-01

    Ethane and propane are the most abundant non-methane hydrocarbons in the atmosphere. However, their emissions, atmospheric distribution, and trends in their atmospheric concentrations are insufficiently understood. Atmospheric model simulations using standard community emission inventories do not reproduce available measurements in the Northern Hemisphere. Here, we show that observations of pre-industrial and present-day ethane and propane can be reproduced in simulations with a detailed atmospheric chemistry transport model, provided that natural geologic emissions are taken into account and anthropogenic fossil fuel emissions are assumed to be two to three times higher than is indicated in current inventories. Accounting for these enhanced ethane and propane emissions results in simulated surface ozone concentrations that are 5-13% higher than previously assumed in some polluted regions in Asia. The improved correspondence with observed ethane and propane in model simulations with greater emissions suggests that the level of fossil (geologic + fossil fuel) methane emissions in current inventories may need re-evaluation.

  17. Natural gas fugitive emissions rates constrained by global atmospheric methane and ethane.

    PubMed

    Schwietzke, Stefan; Griffin, W Michael; Matthews, H Scott; Bruhwiler, Lori M P

    2014-07-15

    The amount of methane emissions released by the natural gas (NG) industry is a critical and uncertain value for various industry and policy decisions, such as for determining the climate implications of using NG over coal. Previous studies have estimated fugitive emissions rates (FER)--the fraction of produced NG (mainly methane and ethane) escaped to the atmosphere--between 1 and 9%. Most of these studies rely on few and outdated measurements, and some may represent only temporal/regional NG industry snapshots. This study estimates NG industry representative FER using global atmospheric methane and ethane measurements over three decades, and literature ranges of (i) tracer gas atmospheric lifetimes, (ii) non-NG source estimates, and (iii) fossil fuel fugitive gas hydrocarbon compositions. The modeling suggests an upper bound global average FER of 5% during 2006-2011, and a most likely FER of 2-4% since 2000, trending downward. These results do not account for highly uncertain natural hydrocarbon seepage, which could lower the FER. Further emissions reductions by the NG industry may be needed to ensure climate benefits over coal during the next few decades.

  18. Kinetics of Ethane Clathrate Hydrate Formation under Titan-Like Conditions

    NASA Astrophysics Data System (ADS)

    Vu, T. H.; Munoz Iglesias, V.; Choukroun, M.; Maynard-Casely, H. E.

    2016-12-01

    Clathrate hydrates are inclusion compounds where small guest molecules are trapped inside highly symmetric water cages. These ice-like crystalline solids are an abundant source of hydrocarbons on Earth that primarily exist in the permafrost and marine sediments. Icy celestial bodies whose pressure and temperature conditions are favorable to the formation of gas hydrates are also expected to contain substantial amounts of these materials. One such example is Saturn's moon Titan, where clathrates are conjectured to be a major crustal component. In fact, clathrate dissociation has been suggested to play a significant role in the replenishment of atmospheric methane on this satellite. In addition to having a substantial atmosphere dominated by nitrogen, Titan is the only body in the Solar System aside from Earth that has standing bodies of liquid on its surface. Liquid methane and ethane have been identified as principal components of the hundreds of lakes that have been observed by the Cassini spacecraft on Titan's surface. As lake fluids come into contact with the pre-existing icy crust, stable layers of ethane clathrate hydrates are expected to form. In this work, we provide experimental evidence for the rapid formation of ethane clathrate from direct contact of liquid ethane with water ice at 1 bar using micro-Raman spectroscopy. Conversion of ice into clathrates is confirmed by the emergence of the characteristic peak at 999 cm-1, which represents the C-C stretch of enclathrated ethane. Kinetics experiments in the temperature range 140-173 K yields an activation energy of 6.75 ± 0.88 kJ/mol for the formation of ethane clathrate. Subsequent thermal analysis indicates a clathrate dissociation temperature of 240 K, consistent with extrapolated literature data. Preliminary synchrotron powder X-ray diffraction experiments have also been carried out to examine the formation kinetics of ethane clathrate from ice/gas mixture at 1 bar. The relatively fast timescale and ease of ethane clathrate formation under these conditions could hold important implications for ethane-methane exchange kinetics and outgassing processes on Titan.

  19. Extraordinary selectivity of CoMo{sub 3}S{sub 13} chalcogel for C{sub 2}H{sub 6} and CO{sub 2} adsorption.

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

    Shafaei-Fallah, M.; Rothenberger, Z.; Katsoulidis, A. P.

    The chalcogel CoMo{sub 3}S{sub 13} is obtained from the reaction of (NH{sub 4}){sub 2}[Mo{sub 3}S{sub 13}] with cobalt acetate in solution. The chalcogel has a BET surface area of 570 m{sup 2} g{sup -1}, and pair distribution function analysis (PDF) and infrared spectroscopy indicate that the [Mo{sub 3}S{sub 13}]{sup 2-} cluster is a building block in the porous network. The CoMo{sub 3}S{sub 13} chalcogel exhibits high selectivity for separating ethane and carbon dioxide from hydrogen and methane.

  20. Microbial mineralization of ethene under sulfate-reducing conditions

    USGS Publications Warehouse

    Bradley, P.M.; Chapelle, F.H.

    2002-01-01

    A limited investigation of the potential for anaerobic ethylene biodegradation under SO4-reducing conditions was performed. Microorganisms indigenous to a lake-bed sediment completely mineralized [1,2-14C] ethylene to 14CO2 when incubated under SO4-reducing conditions. Reliance on ethylene and/or ethane accumulation as a quantitative indicator of complete reductive dechlorination of chloroethylene contaminants may not be warranted. SO4 addition stimulated SO4 reduction as indicated by decreasing SO4 concentrations (> 40% decrease) and production of dissolved sulfide (880 ??M). SO4 amendment completely suppressed the production of ethane and methane. The concomitant absence of ethane and methane production under SO4-amended conditions was consistent with previous conclusions that reduction of ethylene to ethane occurred under methanogenic conditions. A lack of ethylene accumulation under SO4-reducing conditions may reflect insignificant reductive dechlorination of vinyl chloride or efficient anaerobic mineralization of ethylene to CO2.

  1. Behavior of short silica monolithic columns in high pressure gas chromatography.

    PubMed

    Maniquet, Adrien; Bruyer, Nicolas; Raffin, Guy; Baco-Antoniali, Franck; Demesmay, Claire; Dugas, Vincent; Randon, Jérôme

    2016-08-19

    In order to analyze light hydrocarbons mixtures with silica monolithic columns, a conventional gas chromatograph was modified to work with carrier gas pressure as high as 60bar. To understand hydrodynamic flow and retention with short columns (less than 30cm), special attention was required due to the temperature difference between the oven area and the FID detector which contain a significant length of the column. Efficiency and selectivity using various carrier gases (helium, nitrogen and carbon dioxide) at different inlet pressure for different oven temperature were studied. Carrier gas nature was a very significant parameter: on one side, linked to adsorption mechanism for gases like nitrogen and carbon dioxide onto the stationary phase modifying retention and selectivity, on the other side in relation to the minimum theoretical plate height which was as low as 15μm (66 000 platem(-1)) using carbon dioxide as carrier gas. The chromatographic system was then used to separate methane, ethane, ethylene, acetylene, propane, cyclopropane, and butane in less than 30s. Copyright © 2016 Elsevier B.V. All rights reserved.

  2. Geodetic data support trapping of ethane in Titan's polar crust

    NASA Astrophysics Data System (ADS)

    Sotin, Christophe; Rambaux, Nicolas

    2016-04-01

    Titan's surface is characterized by polar depressions that strongly influence interpretations of the gravity data. This study investigates several geodynamical models that can explain these depressions. For each model, the values of the three moments of inertia are computed numerically by discretizing the interior in spherical coordinates. The study shows that a Pratt model where the polar subsurface is made of ethane clathrates can explain the polar depression, the abrupt jump in altitude at about 60 degrees latitude, and the values of the degree 2 gravity coefficients. This model, proposed by Choukroun and Sotin [1], is based on the stability of ethane clathrate hydrates relative to methane clathrate hydrates. In addition to fitting the geodetic data, it explains the absence of ethane in Titan's atmosphere although ethane is the main product of the photolysis of methane. Other geophysical models based on latitudinal variations in the tidal heating production or in the heat flux at the base of the icy crust do not provide such a good match to the gravity and topographic observations. The ethane-clathrate model predicts that all the ethane produced by photolysis of methane at the present rate during the last billion years could be stored in the polar subsurface. It is consistent with the age of Titan's surface and that of Titan's atmospheric methane inferred from geological and geochemical observations by the Cassini/Huygens mission. The present study also emphasizes the role of mass anomalies on the interpretation of the degree 2 gravity coefficients. It shows that for Titan, a slow rotator, the values of the two equatorial moments of inertia (MoI) are largely affected by the polar depressions whereas the value of polar MoI is not. Therefore, as pointed out by previous calculations [2], calculating the moment of inertia (MoI) factor from the value of J2 could lead to major errors. This is not the case for our preferred Titan's model for which the negative polar mass anomalies are compensated at shallow depth by denser ethane-rich clathrates. This work has been performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract to NASA. [1] Choukroun M. and Sotin C. (2012) GRL, 39, L04201. [2] Gao and Stevenson (2013) Icarus, 226, 1185-1191.

  3. Emission of methane, carbon monoxide, carbon dioxide and short‐chain hydrocarbons from vegetation foliage under ultraviolet irradiation

    PubMed Central

    FRASER, WESLEY T.; BLEI, EMANUEL; FRY, STEPHEN C.; NEWMAN, MARK F.; REAY, DAVID S.; SMITH, KEITH A.

    2015-01-01

    Abstract The original report that plants emit methane (CH 4) under aerobic conditions caused much debate and controversy. Critics questioned experimental techniques, possible mechanisms for CH 4 production and the nature of estimating global emissions. Several studies have now confirmed that aerobic CH 4 emissions can be detected from plant foliage but the extent of the phenomenon in plants and the precise mechanisms and precursors involved remain uncertain. In this study, we investigated the role of environmentally realistic levels of ultraviolet (UV) radiation in causing the emission of CH 4 and other gases from foliage obtained from a wide variety of plant types. We related our measured emissions to the foliar content of methyl esters and lignin and to the epidermal UV absorbance of the species investigated. Our data demonstrate that the terrestrial vegetation foliage sampled did emit CH 4, with a range in emissions of 0.6–31.8 ng CH 4 g−1 leaf DW h−1, which compares favourably with the original reports of experimental work. In addition to CH 4 emissions, our data show that carbon monoxide, ethene and propane are also emitted under UV stress but we detected no significant emissions of carbon dioxide or ethane. PMID:25443986

  4. Raman spectrum of methane in nitrogen, carbon dioxide, hydrogen, ethane, and propane environments

    NASA Astrophysics Data System (ADS)

    Petrov, D. V.

    2018-02-01

    Using binary CH4 - mixtures with varied concentrations of H2, N2, CO2, C2H6 and C3H8 and a fixed ambient pressure of 25 bar, the influence of the environment on spectral characteristics (Raman shift, half-width, peak intensity) of Q-branches of the ν1, ν2, ν3, and 2ν4 methane Raman bands are investigated. It is found that depending on the environment these bands demonstrate different changes in their Raman shifts and half-widths. It is shown that the ratios of peak intensities I(ν2)/I(ν1), I(ν3)/I(ν1) and I(2ν4)/I(ν1) are very sensitive to the environment. The Raman shifts and half-widths of CH4 bands are assumed to depend on the absolute concentration of molecules in the analyzed medium. The data obtained would be useful in Raman diagnostics of natural gas.

  5. OPTICAL CONSTANTS AND BAND STRENGTHS OF CH{sub 4}:C{sub 2}H{sub 6} ICES IN THE NEAR- AND MID-INFRARED

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

    Molpeceres, Germán; Ortigoso, Juan; Escribano, Rafael

    2016-07-10

    We present a spectroscopic study of methane–ethane ice mixtures. We have grown CH{sub 4}:C{sub 2}H{sub 6} mixtures with ratios 3:1, 1:1, and 1:3 at 18 and 30 K, plus pure methane and ethane ices, and have studied them in the near-infrared (NIR) and mid-infrared (MIR) ranges. We have determined densities of all species mentioned above. For amorphous ethane grown at 18 and 30 K we have obtained a density of 0.41 and 0.54 g cm{sup −3}, respectively, lower than a previous measurement of the density of the crystalline species, 0.719 g cm{sup −3}. As far as we know this ismore » the first determination of the density of amorphous ethane ice. We have measured band shifts of the main NIR methane and ethane features in the mixtures with respect to the corresponding values in the pure ices. We have estimated band strengths of these bands in the NIR and MIR ranges. In general, intensity decay in methane modes was detected in the mixtures, whereas for ethane no clear tendency was observed. Optical constants of the mixtures at 30 and 18 K have also been evaluated. These values can be used to trace the presence of these species in the surface of trans-Neptunian objects. Furthermore, we have carried out a theoretical calculation of these ice mixtures. Simulation cells for the amorphous solids have been constructed using a Metropolis Monte Carlo procedure. Relaxation of the cells and prediction of infrared spectra have been carried out at density functional theory level.« less

  6. Detection of (C-13)-ethane in Jupiter's atmosphere

    NASA Technical Reports Server (NTRS)

    Wiedemann, Guenter; Bjoraker, Gordon L.; Jennings, Donald E.

    1991-01-01

    High-resolution (C-12)- and (C-13)-ethane spectra of Jupiter were acquired with the Kitt Peak 4 m Fourier spectrometer and the Goddard postdisperser in June 1987. A relative abundance ratio (C-12/C-13) of 94 +/- 12 was derived from the measurements. This nearly terrestrial value indicates little or no fractionation of carbon isotopes when ethane is produced in the photolysis of methane in Jupiter's atmosphere.

  7. Analysis of Non-Methane Hydrocarbon Data from 2004-2016 in a Subtropical Area close to the Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Rappenglueck, B.

    2017-12-01

    Speciated C2-C11 non-methane hydrocarbons (NMHC) have been measured online on an hourly basis at Lake Jackson/TX close to the Gulf of Mexico. Altogether 48 NMHCs along with NO, NO2, NOx, O3 have been collected continuously from January 2004-December 2016 under the auspices of the Texas Commission on Environmental Quality. Data was screened for background conditions representing marine wind sectors. The data set represents a combination of marine air masses mixed with local biogenic emissions. The data analysis addresses photochemical processing of air masses as reflected in the relationship of ln(n-butane/ethane) vs. ln(propane/ethane) and ln(i-butane/ethane) vs. ln(n-butane/ethane). In addition, key NMHC relationships for radical chemistry, e.g. i-butane vs n-butane for OH and Cl chemistry and i-pentane vs. n-pentane for NO3 chemistry, are discussed. Seasonal analysis revealed a clear trend with maximum NMHC mixing ratios in winter time and lowest mixing ratios in summer reflecting the impact of photochemical processes in summer. Propene equivalents were highest during summertime, with significant contributions from alkenes, including isoprene. The relation of propane/ethane vs ethane indicates seasonal variation with lowest values (i.e. most aged air masses) in winter.

  8. Mechanisms for the dehydrogenation of alkanes on platinum: insights gained from the reactivity of gaseous cluster cations, Ptn + n=1-21.

    PubMed

    Adlhart, Christian; Uggerud, Einar

    2007-01-01

    Rates for the dihydrogen elimination of methane, ethane, and propane with cationic platinum clusters, Pt(n) (+) (1

  9. Methane, Ethane, and Propane Sensor for Real-time Leak Detection and Diagnostics

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

    Roscioli, Joseph R.; Herndon, Scott; Nelson, David D.

    2017-03-24

    The Phase I effort demonstrated the technical viability of a fast, sensitive, mobile hydrocarbon monitor. The instrument will enable the oil and gas industry, researchers, and regulators to rapidly identify and chemically profile leaks from facilities. This capability will allow operators to quickly narrow down and mitigate probable leaking equipment, minimizing product loss and penalties due to regulatory non-compliance. During the initial development phase, we demonstrated operation of a prototype monitor that is capable of measuring methane, ethane, and propane at sub-part-per-billion sensitivities in 1 second, using direct absorption infrared spectroscopy. To our knowledge, this is the first instrument capablemore » of fast propane measurements at atmospheric concentrations. In addition, the electrical requirements of the monitor have been reduced from the 1,200 W typical of a spectrometer, to <500 W, making it capable of being powered by a passenger vehicle, and easily deployed by the industry. The prototype monitor leverages recent advances in laser technology, using high-efficiency interband cascade lasers to access the 3 μm region of the mid-infrared, where the methane, ethane, and propane absorptions are strongest. Combined with established spectrometer technology, we have achieved precisions below 200 ppt for each compound. This allows the monitor to measure fast plumes from oil and gas facilities, as well as ambient background concentrations (typical ambient levels are 2 ppm, 1.5 ppb, and 0.7 ppb for methane, ethane and propane, respectively). Increases in instrument operating pressure were studied in order to allow for a smaller 125 W pump to be used, and passive cooling was explored to reduce the cooling load by almost 90% relative to active (refrigerated) cooling. In addition, the simulated infrared absorption profiles of ethane and propane were modified to minimize crosstalk between species, achieving <1% crosstalk between ethane and propane. Finally, a monitor was designed based upon the commercial compact mini-spectrometer capable of dual-laser operation. We intend to build and test this during phase II. Multiple opportunities for improvement were also identified. First, the reported ethane and propane concentrations are susceptible to external acceleration acting upon the instrument. During phase II we will address this “motion-sickness”. Second, significant software development will be needed operate the monitor at 1 second resolution in real time, and provide rapid, actionable data to a driver or passenger.« less

  10. Rapid analysis of dissolved methane, ethylene, acetylene and ethane using partition coefficients and headspace-gas chromatography.

    PubMed

    Lomond, Jasmine S; Tong, Anthony Z

    2011-01-01

    Analysis of dissolved methane, ethylene, acetylene, and ethane in water is crucial in evaluating anaerobic activity and investigating the sources of hydrocarbon contamination in aquatic environments. A rapid chromatographic method based on phase equilibrium between water and its headspace is developed for these analytes. The new method requires minimal sample preparation and no special apparatus except those associated with gas chromatography. Instead of Henry's Law used in similar previous studies, partition coefficients are used for the first time to calculate concentrations of dissolved hydrocarbon gases, which considerably simplifies the calculation involved. Partition coefficients are determined to be 128, 27.9, 1.28, and 96.3 at 30°C for methane, ethylene, acetylene, and ethane, respectively. It was discovered that the volume ratio of gas-to-liquid phase is critical to the accuracy of the measurements. The method performance can be readily improved by reducing the volume ratio of the two phases. Method validation shows less than 6% variation in accuracy and precision except at low levels of methane where interferences occur in ambient air. Method detection limits are determined to be in the low ng/L range for all analytes. The performance of the method is further tested using environmental samples collected from various sites in Nova Scotia.

  11. A post-Cassini view of Titan's methane-based hydrologic cycle

    NASA Astrophysics Data System (ADS)

    Hayes, Alexander G.; Lorenz, Ralph D.; Lunine, Jonathan I.

    2018-05-01

    The methane-based hydrologic cycle on Saturn's largest moon, Titan, is an extreme analogue to Earth's water cycle. Titan is the only planetary body in the Solar System, other than Earth, that is known to have an active hydrologic cycle. With a surface pressure of 1.5 bar and temperatures of 90 to 95 K, methane and ethane condense out of a nitrogen-based atmosphere and flow as liquids on the moon's surface. Exchange processes between atmospheric, surface and subsurface reservoirs produce methane and ethane cloud systems, as well as erosional and depositional landscapes that have strikingly similar forms to their terrestrial counterparts. Over its 13-year exploration of the Saturn system, the Cassini-Huygens mission revealed that Titan's hydrocarbon-based hydrology is driven by nested methane cycles that operate over a range of timescales, including geologic, orbital (for example, Croll-Milankovitch cycles), seasonal and that of a single convective storm. In this Review Article, we describe the dominant exchange processes that operate over these timescales and present a post-Cassini view of Titan's methane-based hydrologic system.

  12. Fugitive methane emission pinpointing and source attribution using ethane measurements in a portable cavity ring-down analyzer

    NASA Astrophysics Data System (ADS)

    Fleck, Derek; Hoffnagle, John; Yiu, John; Chong, Johnston; Tan, Sze

    2017-04-01

    Methane source pinpointing and attribution is ever more important because of the vast network of natural gas distribution which has led to a very large emission sources. Ethane can be used as a tracer to distinguish gas sources between biogenic and natural gas. Having this measurement sensitive enough can even distinguish between gas distributors, or maturity through gas wetness. Here we present data obtained using a portable cavity ring-down spectrometer weighing less than 11 kg and consuming less than 35W that simultaneously measures methane and ethane with a raw 1-σ precision of 50ppb and 4.5ppb, respectively at 2 Hz. These precisions allow for a C2:C1 ratio 1-σ measurement of <0.1% above 10ppm in a single measurement. Utilizing a second onboard laser allows for a high precision methane only mode used for surveying and pinpointing. This mode measures at a rate faster than 4Hz with a 1-σ precision of <3ppb. Because methane seepages are highly variable due to air turbulence and mixing right above the ground, correlations in the variations in C2H6 and CH4 are used to derive a source C2:C1. Additional hardware is needed for steady state concentration measurements to reliably measure the C2:C1 ratio instantaneously. Source discrimination data of local leaks and methane sources using this analysis method are presented. Additionally, two-dimensional plume snapshots are constructed using an integrated onboard GPS to visualize horizontal plane gas propagation.

  13. Strategies for electrooptic film fabrication. Influence of pyrrole-pyridine-based dibranched chromophore architecture on covalent self-assembly, thin-film microstructure, and nonlinear optical response.

    PubMed

    Facchetti, Antonio; Beverina, Luca; van der Boom, Milko E; Dutta, Pulak; Evmenenko, Guennadi; Shukla, Atindra D; Stern, Charlotte E; Pagani, Giorgio A; Marks, Tobin J

    2006-02-15

    The new dibranched, heterocyclic "push-pull" chromophores bis{1-(pyridin-4-yl)-2-[2-(N-methylpyrrol-5-yl)]ethane}methane (1), 1-(pyrid-4-yl)-2-(N-methyl-5-formylpyrrol-2-yl)ethylene (2), {1-(N-methylpyridinium-4-yl)-2-[2-(N-methylpyrrol-5-yl)]ethane}{(1-(pyridin-4-yl)-2-[2-(N-methylpyrrol-5-yl)]ethane}methane (3), N-methyl-2-[1-(N-methylpyrid-4-yl)ethen-2-yl]-5-[pyrid-4-yl]ethen-2-yl]pyrrole iodide (4), bis{1-(N-methyl-4-pyridinio)-2-[2-(N-methylpyrrol-5-yl)]ethane}methane iodide (5), and N-methyl-2,5-[1-(N-methylpyrid-4-yl)ethen-2-yl]pyrrole iodide (6) have been synthesized and characterized. The neutral (1 and 2) and monomethyl salts (3 and 4) undergo chemisorptive reaction with iodobenzyl-functionalized surfaces to afford chromophore monolayers SA-1/SA-2 and SA-3/SA-4, respectively. Molecular structures and other physicochemical properties have been defined by (1)H NMR, optical spectroscopy, and XRD. Thin-film characterization by a variety of techniques (optical spectroscopy, specular X-ray reflectivity, atomic force microscopy, X-ray photoelectron spectroscopy, and angle-dependent polarized second harmonic generation) underscore the importance of the chromophore molecular architecture as well as film growth method on film microstructure and optical/electrooptic response.

  14. Nitrogen Fixation in Thermophilic Chemosynthetic Microbial Communities Depending on Hydrogen, Sulfate, and Carbon Dioxide

    PubMed Central

    Nishihara, Arisa; Haruta, Shin; McGlynn, Shawn E.; Thiel, Vera; Matsuura, Katsumi

    2018-01-01

    The activity of nitrogen fixation measured by acetylene reduction was examined in chemosynthetic microbial mats at 72–75°C in slightly-alkaline sulfidic hot springs in Nakabusa, Japan. Nitrogenase activity markedly varied from sampling to sampling. Nitrogenase activity did not correlate with methane production, but was detected in samples showing methane production levels less than the maximum amount, indicating a possible redox dependency of nitrogenase activity. Nitrogenase activity was not affected by 2-bromo-ethane sulfonate, an inhibitor of methanogenesis. However, it was inhibited by the addition of molybdate, an inhibitor of sulfate reduction and sulfur disproportionation, suggesting the involvement of sulfate-reducing or sulfur-disproportionating organisms. Nitrogenase activity was affected by different O2 concentrations in the gas phase, again supporting the hypothesis of a redox potential dependency, and was decreased by the dispersion of mats with a homogenizer. The loss of activity that occurred from dispersion was partially recovered by the addition of H2, sulfate, and carbon dioxide. These results suggested that the observed activity of nitrogen fixation was related to chemoautotrophic sulfate reducers, and fixation may be active in a limited range of ambient redox potential. Since thermophilic chemosynthetic communities may resemble ancient microbial communities before the appearance of photosynthesis, the present results may be useful when considering the ancient nitrogen cycle on earth. PMID:29367473

  15. Combining tracer flux ratio methodology with low-flying aircraft measurements to estimate dairy farm CH4 emissions

    NASA Astrophysics Data System (ADS)

    Daube, C.; Conley, S.; Faloona, I. C.; Yacovitch, T. I.; Roscioli, J. R.; Morris, M.; Curry, J.; Arndt, C.; Herndon, S. C.

    2017-12-01

    Livestock activity, enteric fermentation of feed and anaerobic digestion of waste, contributes significantly to the methane budget of the United States (EPA, 2016). Studies question the reported magnitude of these methane sources (Miller et. al., 2013), calling for more detailed research of agricultural animals (Hristov, 2014). Tracer flux ratio is an attractive experimental method to bring to this problem because it does not rely on estimates of atmospheric dispersion. Collection of data occurred during one week at two dairy farms in central California (June, 2016). Each farm varied in size, layout, head count, and general operation. The tracer flux ratio method involves releasing ethane on-site with a known flow rate to serve as a tracer gas. Downwind mixed enhancements in ethane (from the tracer) and methane (from the dairy) were measured, and their ratio used to infer the unknown methane emission rate from the farm. An instrumented van drove transects downwind of each farm on public roads while tracer gases were released on-site, employing the tracer flux ratio methodology to assess simultaneous methane and tracer gas plumes. Flying circles around each farm, a small instrumented aircraft made measurements to perform a mass balance evaluation of methane gas. In the course of these two different methane quantification techniques, we were able to validate yet a third method: tracer flux ratio measured via aircraft. Ground-based tracer release rates were applied to the aircraft-observed methane-to-ethane ratios, yielding whole-site methane emission rates. Never before has the tracer flux ratio method been executed with aircraft measurements. Estimates from this new application closely resemble results from the standard ground-based technique to within their respective uncertainties. Incorporating this new dimension to the tracer flux ratio methodology provides additional context for local plume dynamics and validation of both ground and flight-based data.

  16. Using mobile laboratory and aircraft measurements to characterize feedlot emissions and their contribution to atmospheric methane over the Denver-Julesburg Basin

    NASA Astrophysics Data System (ADS)

    Peischl, J.; Eilerman, S. J.; Neuman, J. A.; Aikin, K. C.; Trainer, M.; Ryerson, T. B.

    2016-12-01

    Atmospheric emissions from animal husbandry are important to air quality and climate, but are hard to characterize and quantify as they vary substantially based on management practices, livestock type, and diurnal and seasonal cycles. Using a mobile laboratory, ammonia, methane, nitrous oxide, and carbon dioxide emissions were measured from several concentrated animal feeding operations (CAFOs) in northeastern Colorado. Four CAFOs were chosen for repeated diurnal and seasonal measurements. A consistent diurnal trend in the enhancement ratio of ammonia to the other compounds is clearly observed, with midday enhancement ratios approximately four times greater than nighttime values and average values consistent with statewide inventories and previous literature. These findings are used to develop a source signature for feeding operations in the area. In addition to 250+ CAFOs, the Denver-Julesburg basin (DJB) is a heavily developed oil and natural gas region with over 25,000 wells and numerous compressors and processing plants. Due to the co-location of these varied methane point sources, top-down measurements are often unable to attribute emissions to a specific source or sector. In this work, the CAFO emission signature determined from targeted mobile laboratory measurements is combined with aircraft measurements of ammonia, methane, and ethane during the spring 2015 Shale Oil and Natural Gas Nexus (SONGNEX) field campaign to attribute atmospheric methane over the DJB to either agriculture or fossil fuel sectors.

  17. In situ gas analysis for high pressure applications using property measurements

    NASA Astrophysics Data System (ADS)

    Moeller, J.; Span, R.; Fieback, T.

    2013-10-01

    As the production, distribution, and storage of renewable energy based fuels usually are performed under high pressures and as there is a lack of in situ high pressure gas analysis instruments on the market, the aim of this work was to develop a method for in situ high pressure gas analysis of biogas and hydrogen containing gas mixtures. The analysis is based on in situ measurements of optical, thermo physical, and electromagnetic properties in gas mixtures with newly developed high pressure sensors. This article depicts the calculation of compositions from the measured properties, which is carried out iteratively by using highly accurate equations of state for gas mixtures. The validation of the method consisted of the generation and measurement of several mixtures, of which three are presented herein: a first mixture of 64.9 mol. % methane, 17.1 mol. % carbon dioxide, 9 mol. % helium, and 9 mol. % ethane at 323 K and 423 K in a pressure range from 2.5 MPa to 17 MPa; a second mixture of 93.0 mol. % methane, 4.0 mol. % propane, 2.0 mol. % carbon dioxide, and 1.0 mol. % nitrogen at 303 K, 313 K, and 323 K in a pressure range from 1.2 MPa to 3 MPa; and a third mixture of 64.9 mol. % methane, 30.1 mol. % carbon dioxide, and 5.0 mol. % nitrogen at 303 K, 313 K, and 323 K in a pressure range from 2.5 MPa to 4 MPa. The analysis of the tested gas mixtures showed that with measured density, velocity of sound, and relative permittivity the composition can be determined with deviations below 1.9 mol. %, in most cases even below 1 mol. %. Comparing the calculated compositions with the generated gas mixture, the deviations were in the range of the combined uncertainty of measurement and property models.

  18. Serpentinization processes: Influence of silica

    NASA Astrophysics Data System (ADS)

    Huang, R.; Sun, W.; Ding, X.; Song, M.; Zhan, W.

    2016-12-01

    Serpentinization systems are highly enriched in molecular hydrogen (H2) and hydrocarbons (e.g. methane, ethane and propane). The production of hydrocarbons results from reactions between H2 and oxidized carbon (carbon dioxide and carbon monoxide), which possibly contribute to climate changes during early history of the Earth. However, the influence of silica on the production of H2 and hydrocarbons was poorly constrained. We performed experiments at 311-500 °C and 3.0 kbar using mechanical mixtures of silica and olivine in ratios ranging from 0 to 40%. Molecular hydrogen (H2), methane, ethane and propane were formed, which were analyzed by gas chromatography. It was found that silica largely decreased H2 production. Without any silica, olivine serpentinization produced 94.5 mmol/kg H2 after 20 days of reaction time. By contrast, with the presence of 20% silica, H2 concentrations decreased largely, 8.5 mmol/kg. However, the influence of silica on the production of hydrocarbons is negligible. Moreover, with the addition of 20%-40% silica, the major hydrous minerals are talc, which was quantified according to an established standard curve calibrated by infrared spectroscopy analyses. It shows that silica greatly enhances olivine hydration, especially at 500 °C. Without any addition of silica, reaction extents were <5% at 17 days during olivine serpentinization at 500 °C and 3.0 kbar. By contrast, with the presence of 50% silica, olivine was completely transformed to talc within 9 days. This study indicates that silica impedes the oxidation of ferrous iron into ferric iron, and that rates of olivine hydration in natural geological settings are much faster with silica supply.

  19. Thermodynamic properties of hydrate phases immersed in ice phase

    NASA Astrophysics Data System (ADS)

    Belosludov, V. R.; Subbotin, O. S.; Krupskii, D. S.; Ikeshoji, T.; Belosludov, R. V.; Kawazoe, Y.; Kudoh, J.

    2006-01-01

    Thermodynamic properties and the pressure of hydrate phases immersed in the ice phase with the aim to understand the nature of self-preservation effect of methane hydrate in the framework of macroscopic and microscopic molecular models was studied. It was show that increasing of pressure is happen inside methane hydrate phases immersed in the ice phase under increasing temperature and if the ice structure does not destroy, the methane hydrate will have larger pressure than ice phase. This is because of the thermal expansion of methane hydrate in a few times larger than ice one. The thermal expansion of the hydrate is constrained by the thermal expansion of ice because it can remain in a region of stability within the methane hydrate phase diagram. The utter lack of preservation behavior in CS-II methane- ethane hydrate can be explain that the thermal expansion of ethane-methane hydrate coincide with than ice one it do not pent up by thermal expansion of ice. The pressure and density during the crossing of interface between ice and hydrate was found and dynamical and thermodynamic stability of this system are studied in accordance with relation between ice phase and hydrate phase.

  20. METABOLISM OF CHLORINATED METHANES, ETHANES, AND ETHYLENES BY A MIXED BACTERIAL CUTLURE GROWING ON METHANE

    EPA Science Inventory

    Soil was taken from the top 10 cm of a soil column that removed halogenated aliphatic hydrocarbons in the presence of natural gas. This soil was used as an enrichment inoculum to determine that the removals seen in the soil column were in fact of a microbiological nature. Methane...

  1. Demonstration of a Fast, Precise Propane Measurement Using Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Zahniser, M. S.; Roscioli, J. R.; Nelson, D. D.; Herndon, S. C.

    2016-12-01

    Propane is one of the primary components of emissions from natural gas extraction and processing activities. In addition to being an air pollutant, its ratio to other hydrocarbons such as methane and ethane can serve as a "fingerprint" of a particular facility or process, aiding in identifying emission sources. Quantifying propane has typically required laboratory analysis of flask samples, resulting in low temporal resolution and making plume-based measurements infeasible. Here we demonstrate fast (1-second), high precision (<300 ppt) measurements of propane using high resolution mid-infrared spectroscopy at 2967 wavenumbers. In addition, we explore the impact of nearby water and ethane absorption lines on the accuracy and precision of the propane measurement. Finally, we discuss development of a dual-laser instrument capable of simultaneous measurements of methane, ethane, and propane (the C1-C3 compounds), all within a small spatial package that can be easily deployed aboard a mobile platform.

  2. Measurements of methane emissions from natural gas gathering facilities and processing plants: measurement methods

    DOE PAGES

    Roscioli, J. R.; Yacovitch, T. I.; Floerchinger, C.; ...

    2015-05-07

    Increased natural gas production in recent years has spurred intense interest in methane (CH 4) emissions associated with its production, gathering, processing, transmission, and distribution. Gathering and processing facilities (G&P facilities) are unique in that the wide range of gas sources (shale, coal-bed, tight gas, conventional, etc.) results in a wide range of gas compositions, which in turn requires an array of technologies to prepare the gas for pipeline transmission and distribution. We present an overview and detailed description of the measurement method and analysis approach used during a 20-week field campaign studying CH 4 emissions from the natural gasmore » G&P facilities between October 2013 and April 2014. Dual-tracer flux measurements and on-site observations were used to address the magnitude and origins of CH 4 emissions from these facilities. The use of a second tracer as an internal standard revealed plume-specific uncertainties in the measured emission rates of 20–47%, depending upon plume classification. Furthermore, combining downwind methane, ethane (C 2H 6), carbon monoxide (CO), carbon dioxide (CO 2), and tracer gas measurements with on-site tracer gas release allows for quantification of facility emissions and in some cases a more detailed picture of source locations.« less

  3. Temperature dependence of polyhedral cage volumes in clathrate hydrates

    USGS Publications Warehouse

    Chakoumakos, B.C.; Rawn, C.J.; Rondinone, A.J.; Stern, L.A.; Circone, S.; Kirby, S.H.; Ishii, Y.; Jones, C.Y.; Toby, B.H.

    2003-01-01

    The polyhedral cage volumes of structure I (sI) (carbon dioxide, methane, trimethylene oxide) and structure II (sII) (methane-ethane, propane, tetrahydrofuran, trimethylene oxide) hydrates are computed from atomic positions determined from neutron powder-diffraction data. The ideal structural formulas for sI and sII are, respectively, S2L6 ?? 46H2O and S16L???8 ?? 136H2O, where S denotes a polyhedral cage with 20 vertices, L a 24-cage, and L??? a 28-cage. The space-filling polyhedral cages are defined by the oxygen atoms of the hydrogen-bonded network of water molecules. Collectively, the mean cage volume ratio is 1.91 : 1.43 : 1 for the 28-cage : 24-cage : 20-cage, which correspond to equivalent sphere radii of 4.18, 3.79, and 3.37 A??, respectively. At 100 K, mean polyhedral volumes are 303.8, 227.8, and 158.8 A??3 for the 28-cage, 24-cage, and 20-cage, respectively. In general, the 20-cage volume for a sII is larger than that of a sI, although trimethylene oxide is an exception. The temperature dependence of the cage volumes reveals differences between apparently similar cages with similar occupants. In the case of trimethylene oxide hydrate, which forms both sI and sII, the 20-cages common to both structures contract quite differently. From 220 K, the sII 20-cage exhibits a smooth monotonic reduction in size, whereas the sI 20-cage initially expands upon cooling to 160 K, then contracts more rapidly to 10 K, and overall the sI 20-cage is larger than the sII 20-cage. The volumes of the large cages in both structures contract monotonically with decreasing temperature. These differences reflect reoriented motion of the trimethyelene oxide molecule in the 24-cage of sI, consistent with previous spectroscopic and calorimetric studies. For the 20-cages in methane hydrate (sI) and a mixed methane-ethane hydrate (sII), both containing methane as the guest molecule, the temperature dependence of the 20-cage volume in sII is much less than that in sI, but sII is overall larger in volume.

  4. The identification of liquid ethane in Titan's Ontario Lacus

    USGS Publications Warehouse

    Brown, R.H.; Soderblom, L.A.; Soderblom, J.M.; Clark, R.N.; Jaumann, R.; Barnes, J.W.; Sotin, Christophe; Buratti, B.; Baines, K.H.; Nicholson, P.D.

    2008-01-01

    Titan was once thought to have global oceans of light hydrocarbons on its surface, but after 40 close flybys of Titan by the Cassini spacecraft, it has become clear that no such oceans exist. There are, however, features similar to terrestrial lakes and seas, and widespread evidence for fluvial erosion, presumably driven by precipitation of liquid methane from Titan's dense, nitrogen-dominated atmosphere. Here we report infrared spectroscopic data, obtained by the Visual and Infrared Mapping Spectrometer (VIMS) on board the Cassini spacecraft, that strongly indicate that ethane, probably in liquid solution with methane, nitrogen and other low-molecular-mass hydrocarbons, is contained within Titan's Ontario Lacus.

  5. Assessing the long-term variability of acetylene and ethane in the stratosphere of Jupiter

    NASA Astrophysics Data System (ADS)

    Melin, Henrik; Fletcher, L. N.; Donnelly, P. T.; Greathouse, T. K.; Lacy, J. H.; Orton, G. S.; Giles, R. S.; Sinclair, J. A.; Irwin, P. G. J.

    2018-05-01

    Acetylene (C2H2) and ethane (C2H6) are both produced in the stratosphere of Jupiter via photolysis of methane (CH4). Despite this common source, the latitudinal distribution of the two species is radically different, with acetylene decreasing in abundance towards the pole, and ethane increasing towards the pole. We present six years of NASA IRTF TEXES mid-infrared observations of the zonally-averaged emission of methane, acetylene and ethane. We confirm that the latitudinal distributions of ethane and acetylene are decoupled, and that this is a persistent feature over multiple years. The acetylene distribution falls off towards the pole, peaking at ∼ 30°N with a volume mixing ratio (VMR) of ∼ 0.8 parts per million (ppm) at 1 mbar and still falling off at ± 70° with a VMR of ∼ 0.3 ppm. The acetylene distributions are asymmetric on average, but as we move from 2013 to 2017, the zonally-averaged abundance becomes more symmetric about the equator. We suggest that both the short term changes in acetylene and its latitudinal asymmetry is driven by changes to the vertical stratospheric mixing, potentially related to propagating wave phenomena. Unlike acetylene, ethane has a symmetric distribution about the equator that increases toward the pole, with a peak mole fraction of ∼ 18 ppm at about ± 50° latitude, with a minimum at the equator of ∼ 10 ppm at 1 mbar. The ethane distribution does not appear to respond to mid-latitude stratospheric mixing in the same way as acetylene, potentially as a result of the vertical gradient of ethane being much shallower than that of acetylene. The equator-to-pole distributions of acetylene and ethane are consistent with acetylene having a shorter lifetime than ethane that is not sensitive to longer advective timescales, but is augmented by short-term dynamics, such as vertical mixing. Conversely, the long lifetime of ethane allows it to be transported to higher latitudes faster than it can be chemically depleted.

  6. Numerical Study of Contaminant Effects on Combustion of Hydrogen, Ethane, and Methane in Air

    NASA Technical Reports Server (NTRS)

    Lai, H. T.; Thomas, S. R.

    1995-01-01

    A numerical study was performed to assess the effects of vitiated air on the chemical kinetics of hydrogen, ethane, and methane combustion with air. A series of calculations in static reacting systems was performed, where the initial temperature was specified and reactions occurred at constant pressure. Three different types of test flow contaminants were considered: NP, H2O, and a combustion of H2O and CO2. These contaminants are present in the test flows of facilities used for hypersonic propulsion testing. The results were computed using a detailed reaction mechanism and are presented in terms of ignition and reaction times. Calculations were made for a wide range of contaminant concentrations, temperatures and pressures. The results indicate a pronounced kinetic effect over a range of temperatures, especially with NO contamination and, to a lesser degree, with H2O contamination. In all cases studied, CO2 remained kinetically inert, but had a thermodynamic effect on results by acting as a third body. The largest effect is observed with combustion using hydrogen fuel, less effect is seen with combustion of ethane, and little effect of contaminants is shown with methane combustion.

  7. Numerical study of contaminant effects on combustion of hydrogen, ethane, and methane in air

    NASA Technical Reports Server (NTRS)

    Lai, H. T.; Thomas, S. R.

    1995-01-01

    A numerical study was performed to assess the effects of vitiated air on the chemical kinetics of hydrogen, ethane, and methane combustion with air. A series of calculations in static reacting systems was performed, where the initial temperature was specified and reactions occurred at constant pressure. Three different types of test flow contaminants were considered: NO, H2O, and a combination of H2O and CO2. These contaminants are present in the test flows of facilities used for hypersonic propulsion testing. The results were computed using a detailed reaction mechanism and are presented in terms of ignition and reaction times. Calculations were made for a wide range of contaminant concentrations, temperatures and pressures. The results indicate a pronounced kinetic effect over a range of temperatures, especially with NO contamination and, to a lesser degree, with H2O contamination. In all cases studied, CO2 remained kinetically inert, but had a thermodynamically effect on results by acting as a third body. The largest effect is observed with combustion using hydrogen fuel, less effect is seen with combustion of ethane, and little effect of contaminants is shown with methane combustion.

  8. Biodegradation of individual and multiple chlorinated aliphatic hydrocarbons by methane-oxidizing cultures.

    PubMed Central

    Chang, H L; Alvarez-Cohen, L

    1996-01-01

    The microbial degradation of chlorinated and nonchlorinated methanes, ethanes, and ethanes by a mixed methane-oxidizing culture grown under chemostat and batch conditions is evaluated and compared with that by two pure methanotrophic strains: CAC1 (isolated from the mixed culture) and Methylosinus trichosporium OB3b. With the exception of 1,1-dichloroethylene, the transformation capacity (Tc) for each chlorinated aliphatic hydrocarbon was generally found to be in inverse proportion to its chlorine content within each aliphatic group (i.e., methanes, ethanes, and ethenes), whereas similar trends were not observed for degradation rate constants. Tc trends were similar for all methane-oxidizing cultures tested. None of the cultures were able to degrade the fully chlorinated aliphatics such as perchloroethylene and carbon tetrachloride. Of the four cultures tested, the chemostat-grown mixed culture exhibited the highest Tc for trichloroethylene, cis-1,2-dichloroethylene, tetrachloroethane, 1,1,1-trichloroethane, and 1,2-dichloroethane, whereas the pure batch-grown OB3b culture exhibited the highest Tc for all other compounds tested. The product toxicity of chlorinated aliphatic hydrocarbons in a mixture containing multiple compounds was cumulative and predictable when using parameters measured from the degradation of individual compounds. The Tc for each chlorinated aliphatic hydrocarbon in a mixture (Tcmix) and the total Tc for the mixture (sigma Tcmix) are functions of the individual Tc, the initial substrate concentration (S0), and the first-order rate constant (k/Ks) of each compound in the mixture, indicating the importance of identifying the properties and compositions of all potentially degradable compounds in a contaminant mixture. PMID:8795228

  9. Experimental determination of the kinetics of formation of the benzene-ethane co-crystal and implications for Titan

    NASA Astrophysics Data System (ADS)

    Cable, Morgan L.; Vu, Tuan H.; Hodyss, Robert; Choukroun, Mathieu; Malaska, Michael J.; Beauchamp, Patricia

    2014-08-01

    Benzene is found on Titan and is a likely constituent of the putative evaporite deposits formed around the hydrocarbon lakes. We have recently demonstrated the formation of a benzene-ethane co-crystal under Titan-like surface conditions. Here we investigate the kinetics of formation of this new structure as a function of temperature. We show that the formation process would reach completion under Titan surface conditions in ~18 h and that benzene precipitates from liquid ethane as the co-crystal. This suggests that benzene-rich evaporite basins around ethane/methane lakes and seas may not contain pure crystalline benzene, but instead benzene-ethane co-crystals. This co-crystalline form of benzene with ethane represents a new class of materials for Titan's surface, analogous to hydrated minerals on Earth. This new structure may also influence evaporite characteristics such as particle size, dissolution rate, and infrared spectral properties.

  10. The bulk isotopic composition of hydrocarbons in subaerial volcanic-hydrothermal emissions from different tectonic settings

    NASA Astrophysics Data System (ADS)

    Fiebig, J.; Tassi, F.; Vaselli, O.; Viveiros, M. F.; Silva, C.; Lopez, T. M.; D'Alessandro, W.; Stefansson, A.

    2015-12-01

    Assuming that methane and its higher chain homologues derive from a common source, carbon isotope patterns have been applied as a criterion to identify occurrences of abiogenic hydrocarbons. Based on these, it has been postulated that abiogenic hydrocarbon production occurs within several (ultra)mafic environments. More evolved volcanic-hydrothermal systems may also provide all the prerequisites necessary for abiogenic hydrocarbon production, such as availability of inorganic CO2, hydrogen and heat. We have investigated the chemical and isotopic composition of n-alkanes contained within subaerial hydrothermal discharges emitted from a range of hot spot, subduction and rift-related volcanoes to determine the origin of hydrocarbons in these systems. Amongst these are Nisyros (Greece), Vesuvio, Campi Flegrei, Ischia, Pantelleria and Vulcano (all Italy), Mt. Mageik and Trident (USA), Copahue (Argentina), Teide (Spain), Furnas and Fogo (Portugal). The carbon isotopic composition of methane emitted from these sites varies from -65 to -8‰ , whereas δ13C of ethane and propane exhibit a much narrower variation from -17‰ to -31‰. Methane that occurs most enriched in 13C is also characterized by relatively positive δD values ranging up to -80‰. Carbon isotope reversals between methane and ethane are only observed for locations exhibiting δ13C-CH4 values > -20‰, such as Teide, Pantelleria, Trident and Furnas. At Furnas, δ13C-CH4 varies by 50‰ within a relatively short distance of <50m between two vents, whereas δ13C-C2H6 varies by less than 2‰ only. For some of the investigated locations apparent carbon isotopic temperatures between methane and CO2 are in agreement with those derived from gas concentration geothermometers. At these locations methane, however seems to be in disequilibrium with ethane and propane. These findings imply that methane on the one hand and the C2+ hydrocarbons on the other hand often might derive from distinct sources.

  11. a Hamiltonian to Obtain a Global Frequency Analysis of all the Vibrational Bands of Ethane

    NASA Astrophysics Data System (ADS)

    Moazzen-Ahmadi, Nasser; Norooz Oliaee, Jalal

    2016-06-01

    The interest in laboratory spectroscopy of ethane stems from the desire to understand the methane cycle in the atmospheres of planets and their moons and from the importance of ethane as a trace species in the terrestrial atmosphere. Solar decomposition of methane in the upper part of these atmospheres followed by a series of reactions leads to a variety of hydrocarbon compounds among which ethane is often the second most abundant species. Because of its high abundance, ethane spectra have been measured by Voyager and Cassini in the regions around 30, 12, 7, and 3 μm. Therefore, a complete knowledge of line parameters of ethane is crucial for spectroscopic remote sensing of planetary atmospheres. Experimental characterization of torsion-vibration states of ethane lying below 1400 cm-1 have been made previously, but extension of the Hamiltonian model for treatment of the strongly perturbed νb{8} fundamental and the complex band system of ethane in the 3 micron region requires careful examination of the operators for many new torsionally mediated vibration-rotation interactions. Following the procedures outlined by Hougen, we have re-examined the transformation properties of the total angular momentum, the translational and vibrational coordinates and momenta of ethane, and for vibration-torsion-rotation interaction terms constructed by taking products of these basic operators. It is found that for certain choices of phase, the doubly degenerate vibrational coordinates with and symmetry can be made to transform under the group elements in such a way as to yield real matrix elements for the torsion-vibration-rotation couplings whereas other choices of phase may require complex algebra. In this talk, I will discuss the construction of a very general torsion-vibration-rotation Hamiltonian for ethane, as well as the prospect for using such a Hamiltonian to obtain a global frequency analysis (based in large part on an extension of earlier programs and ethane fits^a from our laboratory) of all the vibrational bands of ethane at or below the 3-micron region. N. Moazzen-Ahmadi and J. Norooz Oliaee, J. Quant. Spectrosc. Radiat. Transfer, submitted. J.T. Hougen, Can. J. Phys., 42, 1920 (1964) J. T. Hougen, Can. J. Phys., 43, 935 (1965)

  12. Pyrolysis process for the treatment of food waste.

    PubMed

    Grycová, Barbora; Koutník, Ivan; Pryszcz, Adrian

    2016-10-01

    Different waste materials were pyrolysed in the laboratory pyrolysis unit to the final temperature of 800°C with a 10min delay at the final temperature. After the pyrolysis process a mass balance of the resulting products, off-line analysis of the pyrolysis gas and evaluation of solid and liquid products were carried out. The gas from the pyrolysis experiments was captured discontinuously into Tedlar gas sampling bags and the selected components were analyzed by gas chromatography (methane, ethene, ethane, propane, propene, hydrogen, carbon monoxide and carbon dioxide). The highest concentration of measured hydrogen (WaCe 61%vol.; WaPC 66%vol.) was analyzed at the temperature from 750 to 800°C. The heating values of the solid and liquid residues indicate the possibility of its further use for energy recovery. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Chemical markers of possible hot spots on Mars

    NASA Astrophysics Data System (ADS)

    Wong, Ah-San; Atreya, Sushil K.; Encrenaz, Thérèse

    2003-04-01

    Although there is no evidence of active volcanism on Mars today, ``localized'' outgassing sources, the hot spots, may not be ruled out. If outgassing does occur somewhere on Mars, water, carbon dioxide, sulfur species, methane, and to a lesser extent, halogens would be the likely molecules of outgassing, based on terrestrial analogs. The sulfur species, methane, and halogens have not been detected in the Martian atmosphere, but the observations were averaged over large areas, which could result in substantial dilution in abundances. If the interpretation of certain Mars Global Surveyor images indicating recent ground water seepage and surface runoff [Malin and Edgett, 2000] is correct, it may imply that Mars could still be active internally in some places from time to time, and outgassing of the abovementioned species may occur with or without the water seepage. Moreover, if the tentative detection of formaldehyde (CH2O) in the equatorial region of Mars [Korablev et al., 1993] is confirmed by future observations, it would imply at least local outgassing of methane, whose oxidation results in the formation of CH2O. Considering the possibility of outgassing from some localized hot spots, we have developed a one-dimensional photochemical model that includes methane (CH4), sulfur dioxide (SO2), and hydrogen sulfide (H2S), starting with their current ``global average'' upper limits of 0.02, 0.1, and 0.1 ppm at the surface, respectively, and then progressively increasing their abundances above possible hot spots. We find that the introduction of methane into the Martian atmosphere results in the formation of mainly formaldehyde, methyl alcohol (CH3OH), and ethane (C2H6), whereas the introduction of the sulfur species produces mainly sulfur monoxide (SO) and sulfuric acid (H2SO4). The effect of outgassed halogens on the Martian atmosphere is found to be negligible. Depending upon the flux of outgassed molecules from possible hot spots, some of these species and the resulting new molecules may be detectable locally, either by remote sensing or in situ measurements.

  14. Prediction of vapour-liquid and vapour-liquid-liquid equilibria of nitrogen-hydrocarbon mixtures used in J-T refrigerators

    NASA Astrophysics Data System (ADS)

    Narayanan, Vineed; Venkatarathnam, G.

    2018-03-01

    Nitrogen-hydrocarbon mixtures are widely used as refrigerants in J-T refrigerators operating with mixtures, as well as in natural gas liquefiers. The Peng-Robinson equation of state has traditionally been used to simulate the above cryogenic process. Multi parameter Helmholtz energy equations are now preferred for determining the properties of natural gas. They have, however, been used only to predict vapour-liquid equilibria, and not vapour-liquid-liquid equilibria that can occur in mixtures used in cryogenic mixed refrigerant processes. In this paper the vapour-liquid equilibrium of binary mixtures of nitrogen-methane, nitrogen-ethane, nitrogen-propane, nitrogen-isobutane and three component mixtures of nitrogen-methane-ethane and nitrogen-methane-propane have been studied with the Peng-Robinson and the Helmholtz energy equations of state of NIST REFPROP and compared with experimental data available in the literature.

  15. The identification of liquid ethane in Titan's Ontario Lacus

    USGS Publications Warehouse

    Brown, R.H.; Soderblom, L.A.; Soderblom, J.M.; Clark, R.N.; Jaumann, R.; Barnes, J.W.; Sotin, Christophe; Buratti, B.; Baines, K.H.; Nicholson, P.D.

    2008-01-01

    Titan was once thought to have global oceans of light hydrocarbons on its surface, but after 40 close flybys of Titan by the Cassini spacecraft, it has become clear that no such oceans exist. There are, however, features similar to terrestrial lakes and seas, and widespread evidence for fluvial erosion, presumably driven by precipitation of liquid methane from Titan's dense, nitrogen-dominated atmosphere. Here we report infrared spectroscopic data, obtained by the Visual and Infrared Mapping Spectrometer (VIMS) on board the Cassini spacecraft, that strongly indicate that ethane, probably in liquid solution with methane, nitrogen and other low-molecular-mass hydrocarbons, is contained within Titan's Ontario Lacus. ??2008 Macmillan Publishers Limited. All rights reserved.

  16. Methane Fingerprinting: Isotopic Methane and Ethane-to-Methane Ratio Analysis Using a Cavity Ring-Down Spectrometer

    NASA Astrophysics Data System (ADS)

    Saad, Nabil; Fleck, Derek; Hoffnagle, John

    2016-04-01

    Emissions of Natural gas, and methane (CH4) specifically, have come under increased scrutiny by virtue of methane's 28-36x greenhouse warming potential compared to carbon dioxide (CO2) while accounting for 10% of the total greenhouse gas emissions in the US. Large uncontrolled leaks, such as the recent Aliso Canyon leak, originating from uncapped wells, coal mines and storage facilities have increased the total global contribution of methane missions even further. Determining the specific fingerprint of methane sources, by quantifying δ13C values and C2:C1 ratios, provides the means to understand methane producing processes and allows for sources of methane to be mapped and classified through these processes; i.e. biogenic vs. thermogenic, wet vs dry. In this study we present a fully developed Cavity Ring-Down Spectrometer (CRDS) that precisely measures 12CH4 concentration and its 13CH4 isotope concentration, yielding δ13C measurements, C2H6 concentration, along with CO2 and H2O. This provides real-time continuous measurements without an upfront separation requirement or multiple analyses to derive the origin of the gas samples. The highly sensitive analyzer allows for measurements of scarce molecules down to sub-ppb 1-σ precision in 5 minutes of measurement: with CH4 <0.1ppb, δ13C <1‰ C2H6 <1ppb and CO2 <1ppm. To complement this work, we provide the analysis of different methane sources providing a 2-dimensional mapping of methane sources as functions of δ13C and C2:C1 ratios, which can be thought of as a modified Bernard Plot. This dual ratio mapping can be used to discriminate between naturally occurring biogenic methane sources, naturally occurring enriched thermogenic sources, and natural gas distribution sources. This also shows future promise in aiding gas and oil exploration, in distinguishing oil vs coal gases, as well as a valuable tool in the development of methane sequestration.

  17. Near-infrared incoherent broadband cavity enhanced absorption spectroscopy (NIR-IBBCEAS) for detection and quantification of natural gas components.

    PubMed

    Prakash, Neeraj; Ramachandran, Arun; Varma, Ravi; Chen, Jun; Mazzoleni, Claudio; Du, Ke

    2018-06-28

    The principle of near-infrared incoherent broadband cavity enhanced absorption spectroscopy was employed to develop a novel instrument for detecting natural gas leaks as well as for testing the quality of natural gas mixtures. The instrument utilizes the absorption features of methane, butane, ethane, and propane in the wavelength region of 1100 nm to 1250 nm. The absorption cross-section spectrum in this region for methane was adopted from the HITRAN database, and those for the other three gases were measured in the laboratory. A singular-value decomposition (SVD) based analysis scheme was employed for quantifying methane, butane, ethane, and propane by performing a linear least-square fit. The developed instrument achieved a detection limit of 460 ppm, 141 ppm, 175 ppm and 173 ppm for methane, butane, ethane, and propane, respectively, with a measurement time of 1 second and a cavity length of 0.59 m. These detection limits are less than 1% of the Lower Explosive Limit (LEL) for each gas. The sensitivity can be further enhanced by changing the experimental parameters (such as cavity length, lamp power etc.) and using longer averaging intervals. The detection system is a low-cost and portable instrument suitable for performing field monitorings. The results obtained on the gas mixture emphasize the instrument's potential for deployment at industrial facilities dealing with natural gas, where potential leaks pose a threat to public safety.

  18. Variability in Spatially and Temporally Resolved Emissions and Hydrocarbon Source Fingerprints for Oil and Gas Sources in Shale Gas Production Regions.

    PubMed

    Allen, David T; Cardoso-Saldaña, Felipe J; Kimura, Yosuke

    2017-10-17

    A gridded inventory for emissions of methane, ethane, propane, and butanes from oil and gas sources in the Barnett Shale production region has been developed. This inventory extends previous spatially resolved inventories of emissions by characterizing the overall variability in emission magnitudes and the composition of emissions at an hourly time resolution. The inventory is divided into continuous and intermittent emission sources. Sources are defined as continuous if hourly averaged emissions are greater than zero in every hour; otherwise, they are classified as intermittent. In the Barnett Shale, intermittent sources accounted for 14-30% of the mean emissions for methane and 10-34% for ethane, leading to spatial and temporal variability in the location of hourly emissions. The combined variability due to intermittent sources and variability in emission factors can lead to wide confidence intervals in the magnitude and composition of time and location-specific emission inventories; therefore, including temporal and spatial variability in emission inventories is important when reconciling inventories and observations. Comparisons of individual aircraft measurement flights conducted in the Barnett Shale region versus the estimated emission rates for each flight from the emission inventory indicate agreement within the expected variability of the emission inventory for all flights for methane and for all but one flight for ethane.

  19. Methane emissions from natural gas infrastructure and use in the urban region of Boston, Massachusetts.

    PubMed

    McKain, Kathryn; Down, Adrian; Raciti, Steve M; Budney, John; Hutyra, Lucy R; Floerchinger, Cody; Herndon, Scott C; Nehrkorn, Thomas; Zahniser, Mark S; Jackson, Robert B; Phillips, Nathan; Wofsy, Steven C

    2015-02-17

    Methane emissions from natural gas delivery and end use must be quantified to evaluate the environmental impacts of natural gas and to develop and assess the efficacy of emission reduction strategies. We report natural gas emission rates for 1 y in the urban region of Boston, using a comprehensive atmospheric measurement and modeling framework. Continuous methane observations from four stations are combined with a high-resolution transport model to quantify the regional average emission flux, 18.5 ± 3.7 (95% confidence interval) g CH4 ⋅ m(-2) ⋅ y(-1). Simultaneous observations of atmospheric ethane, compared with the ethane-to-methane ratio in the pipeline gas delivered to the region, demonstrate that natural gas accounted for ∼ 60-100% of methane emissions, depending on season. Using government statistics and geospatial data on natural gas use, we find the average fractional loss rate to the atmosphere from all downstream components of the natural gas system, including transmission, distribution, and end use, was 2.7 ± 0.6% in the Boston urban region, with little seasonal variability. This fraction is notably higher than the 1.1% implied by the most closely comparable emission inventory.

  20. Methane emissions from natural gas infrastructure and use in the urban region of Boston, Massachusetts

    PubMed Central

    McKain, Kathryn; Down, Adrian; Raciti, Steve M.; Budney, John; Hutyra, Lucy R.; Floerchinger, Cody; Herndon, Scott C.; Nehrkorn, Thomas; Zahniser, Mark S.; Jackson, Robert B.; Phillips, Nathan; Wofsy, Steven C.

    2015-01-01

    Methane emissions from natural gas delivery and end use must be quantified to evaluate the environmental impacts of natural gas and to develop and assess the efficacy of emission reduction strategies. We report natural gas emission rates for 1 y in the urban region of Boston, using a comprehensive atmospheric measurement and modeling framework. Continuous methane observations from four stations are combined with a high-resolution transport model to quantify the regional average emission flux, 18.5 ± 3.7 (95% confidence interval) g CH4⋅m−2⋅y−1. Simultaneous observations of atmospheric ethane, compared with the ethane-to-methane ratio in the pipeline gas delivered to the region, demonstrate that natural gas accounted for ∼60–100% of methane emissions, depending on season. Using government statistics and geospatial data on natural gas use, we find the average fractional loss rate to the atmosphere from all downstream components of the natural gas system, including transmission, distribution, and end use, was 2.7 ± 0.6% in the Boston urban region, with little seasonal variability. This fraction is notably higher than the 1.1% implied by the most closely comparable emission inventory. PMID:25617375

  1. 40 CFR 63.772 - Test methods, compliance procedures, and compliance demonstrations.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Oil and Natural Gas Production Facilities § 63.772 Test methods, compliance procedures, and compliance...) A mixture of methane in air at a concentration less than 10,000 parts per million by volume. (5) An... methane and ethane) or total HAP (Ei, Eo) shall be computed using the equations and procedures specified...

  2. 40 CFR 63.496 - Back-end process provisions-procedures to determine compliance with residual organic HAP...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... methods of determining this quantity are production records, measurement of stream characteristics, and... HAP (or TOC, minus methane and ethane) emissions in all process vent streams and primary and secondary... heater. (B) Paragraph (b)(5)(iii) of this section is applicable, except that TOC (minus methane and...

  3. 40 CFR 63.496 - Back-end process provisions-procedures to determine compliance with residual organic HAP...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... methods of determining this quantity are production records, measurement of stream characteristics, and... HAP (or TOC, minus methane and ethane) emissions in all process vent streams and primary and secondary... heater. (B) Paragraph (b)(5)(iii) of this section is applicable, except that TOC (minus methane and...

  4. 40 CFR 63.496 - Back-end process provisions-procedures to determine compliance with residual organic HAP...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... methods of determining this quantity are production records, measurement of stream characteristics, and... HAP (or TOC, minus methane and ethane) emissions in all process vent streams and primary and secondary... heater. (B) Paragraph (b)(5)(iii) of this section is applicable, except that TOC (minus methane and...

  5. 40 CFR 63.496 - Back-end process provisions-procedures to determine compliance with residual organic HAP...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... methods of determining this quantity are production records, measurement of stream characteristics, and... HAP (or TOC, minus methane and ethane) emissions in all process vent streams and primary and secondary... heater. (B) Paragraph (b)(5)(iii) of this section is applicable, except that TOC (minus methane and...

  6. 40 CFR 63.772 - Test methods, compliance procedures, and compliance demonstrations.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Oil and Natural Gas Production Facilities § 63.772 Test methods, compliance procedures, and compliance...) A mixture of methane in air at a concentration less than 10,000 parts per million by volume. (5) An... methane and ethane) or total HAP (Ei, Eo) shall be computed using the equations and procedures specified...

  7. Titan. [Voyager IRIS observation of satellite atmosphere

    NASA Technical Reports Server (NTRS)

    Lunine, Jonathan I.

    1990-01-01

    Saturn's satellite Titan is the second-largest in the solar system. Its dense atmosphere is mostly molecular nitrogen with an admixture of methane, a surface pressure of 1.5 bars and a surface temperature of 94K. The fundamental driving force in the long-term evolution of Titan's atmosphere is the photolysis of methane in the stratosphere to form higher hydrocarbons and aerosols. The current rate of photolysis and undersaturation of methane in the lower troposphere suggests the presence of a massive ethane-methane-nitrogen ocean. The ocean evolves to a more ethane-rich state over geologic time, driving changes in the atmospheric thermal structure. An outstanding issue concerning Titan's earliest history is the origin of atmospheric nitrogen: was it introduced into Titan as molecular nitrogen or ammonia? Measurement of the argon-to-nitrogen ratio in the present atmosphere provides a diagnostic test of these competing hypotheses. Many of the questions raised by the Voyager encounters about Titan and its atmosphere can be adequately addressed only by an entry probe, such as that planned for the Cassini mission.

  8. A numerical analysis of heat and mass transfer during the steam reforming process of ethane

    NASA Astrophysics Data System (ADS)

    Tomiczek, Marcin; Kaczmarczyk, Robert; Mozdzierz, Marcin; Brus, Grzegorz

    2017-11-01

    This paper presents a numerical analysis of heat and mass transfer during the steam reforming of ethane. From a chemical point of view, the reforming process of heavy hydrocarbons, such as ethane, is complex. One of the main issue is a set of undesired chemical reactions that causes the deposition of solid carbon and consequently blocks the catalytic property of a reactor. In the literature a carbon deposition regime is selected by thermodynamical analysis to design safe operation conditions. In the case of Computational Fluid Dynamic (CFD, hereafter) models each control volume should be investigated to determinate if carbon deposition is thermodynamically favourable. In this paper the authors combine equilibrium and kinetics analysis to simulate the steam reforming of methane-ethane rich fuel. The results of the computations were juxtaposed with experimental data for methane steam reforming, and good agreement was found. An analysis based on the kinetics of reactions was conducted to predict the influence of temperature drop and non-equilibrium composition on solid carbon deposition. It was found that strong non-uniform temperature distribution in the reactor causes conditions favourable for carbon deposition at the inlet of the reformer. It was shown that equilibrium calculations, often used in the literature, are insufficient.

  9. Muon radiolysis affected by density inhomogeneity in near-critical fluids.

    PubMed

    Cormier, P J; Alcorn, C; Legate, G; Ghandi, K

    2014-04-01

    In this article we show the significant tunability of radiation chemistry in supercritical ethane and to a lesser extent in near critical CO2. The information was obtained by studies of muonium (Mu = μ(+)e(-)), which is formed by the thermalization of positive muons in different materials. The studies of the proportions of three fractions of muon polarization, PMu, diamagnetic PD and lost fraction, PL provided the information on radiolysis processes involved in muon thermalization. Our studies include three different supercritical fluids, water, ethane and carbon dioxide. A combination of mobile electrons and other radiolysis products such as (•)C2H5 contribute to interesting behavior at densities ∼40% above the critical point in ethane. In carbon dioxide, an increase in electron mobility contributes to the lost fraction. The hydrated electron in water is responsible for the lost fraction and decreases the muonium fraction.

  10. Kinetics of methane-ethane gas replacement in clathrate-hydrates studied by time-resolved neutron diffraction and Raman spectroscopy.

    PubMed

    Murshed, M Mangir; Schmidt, Burkhard C; Kuhs, Werner F

    2010-01-14

    The kinetics of CH(4)-C(2)H(6) replacement in gas hydrates has been studied by in situ neutron diffraction and Raman spectroscopy. Deuterated ethane structure type I (C(2)H(6) sI) hydrates were transformed in a closed volume into methane-ethane mixed structure type II (CH(4)-C(2)H(6) sII) hydrates at 5 MPa and various temperatures in the vicinity of 0 degrees C while followed by time-resolved neutron powder diffraction on D20 at ILL, Grenoble. The role of available surface area of the sI starting material on the formation kinetics of sII hydrates was studied. Ex situ Raman spectroscopic investigations were carried out to crosscheck the gas composition and the distribution of the gas species over the cages as a function of structure type and compared to the in situ neutron results. Raman micromapping on single hydrate grains showed compositional and structural gradients between the surface and core of the transformed hydrates. Moreover, the observed methane-ethane ratio is very far from the one expected for a formation from a constantly equilibrated gas phase. The results also prove that gas replacement in CH(4)-C(2)H(6) hydrates is a regrowth process involving the nucleation of new crystallites commencing at the surface of the parent C(2)H(6) sI hydrate with a progressively shrinking core of unreacted material. The time-resolved neutron diffraction results clearly indicate an increasing diffusion limitation of the exchange process. This diffusion limitation leads to a progressive slowing down of the exchange reaction and is likely to be responsible for the incomplete exchange of the gases.

  11. 40 CFR 63.772 - Test methods, compliance procedures, and compliance demonstrations.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Oil and Natural Gas Production Facilities § 63.772 Test methods, compliance procedures, and compliance...) A mixture of methane in air at a concentration less than 10,000 parts per million by volume. (5) An... rate of either TOC (minus methane and ethane) or total HAP (Ei, Eo) shall be computed using the...

  12. 40 CFR 63.772 - Test methods, compliance procedures, and compliance demonstrations.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Oil and Natural Gas Production Facilities § 63.772 Test methods, compliance procedures, and compliance...) A mixture of methane in air at a concentration less than 10,000 parts per million by volume. (5) An... rate of either TOC (minus methane and ethane) or total HAP (Ei, Eo) shall be computed using the...

  13. 77 FR 10424 - Approval and Promulgation of Implementation Plans; Wisconsin; Volatile Organic Compound Emission...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-02-22

    ... organic compounds (TOC) (minus methane and ethane) by 98 weight-percent or to a TOC (minus methane and...- effectiveness) per unit reduction of TOC associated with an individual vent stream, based on vent stream flow rate, emission rate of TOC, net heating value and corrosion properties, whether or not the vent stream...

  14. 40 CFR Figure 1 to Subpart G of... - Definitions of Terms Used in Wastewater Equations

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... wastewater, ppmw. CG=Concentration of TOC (minus methane and ethane) or total organic hazardous air pollutants, in vented gas stream, dry basis, ppmv. CGc=Concentration of TOC or organic hazardous air... flow rate of vented gas stream, dry standard, m3/min. QMG=Mass flowrate of TOC (minus methane and...

  15. Biological formation of ethane and propane in the deep marine subsurface.

    PubMed

    Hinrichs, Kai-Uwe; Hayes, John M; Bach, Wolfgang; Spivack, Arthur J; Hmelo, Laura R; Holm, Nils G; Johnson, Carl G; Sylva, Sean P

    2006-10-03

    Concentrations and isotopic compositions of ethane and propane in cold, deeply buried sediments from the southeastern Pacific are best explained by microbial production of these gases in situ. Reduction of acetate to ethane provides one feasible mechanism. Propane is enriched in (13)C relative to ethane. The amount is consistent with derivation of the third C from inorganic carbon dissolved in sedimentary pore waters. At typical sedimentary conditions, the reactions yield free energy sufficient for growth. Relationships with competing processes are governed mainly by the abundance of H(2). Production of C(2) and C(3) hydrocarbons in this way provides a sink for acetate and hydrogen but upsets the general belief that hydrocarbons larger than methane derive only from thermal degradation of fossil organic material.

  16. Biological formation of ethane and propane in the deep marine subsurface

    PubMed Central

    Hinrichs, Kai-Uwe; Hayes, John M.; Bach, Wolfgang; Spivack, Arthur J.; Hmelo, Laura R.; Holm, Nils G.; Johnson, Carl G.; Sylva, Sean P.

    2006-01-01

    Concentrations and isotopic compositions of ethane and propane in cold, deeply buried sediments from the southeastern Pacific are best explained by microbial production of these gases in situ. Reduction of acetate to ethane provides one feasible mechanism. Propane is enriched in 13C relative to ethane. The amount is consistent with derivation of the third C from inorganic carbon dissolved in sedimentary pore waters. At typical sedimentary conditions, the reactions yield free energy sufficient for growth. Relationships with competing processes are governed mainly by the abundance of H2. Production of C2 and C3 hydrocarbons in this way provides a sink for acetate and hydrogen but upsets the general belief that hydrocarbons larger than methane derive only from thermal degradation of fossil organic material. PMID:16990430

  17. Quantifying Emissions from the Eagle Ford Shale Using Ethane Enhancement

    NASA Astrophysics Data System (ADS)

    Roest, G. S.; Schade, G. W.

    2014-12-01

    Emissions from unconventional oil and natural gas exploration in the Eagle Ford Shale have been conjectured as a contributing factor to increasing ozone concentrations in the San Antonio Metropolitan Area, which is on track to be designated as a nonattainment area by the EPA. Primary species found in natural gas emissions are alkanes, with C3 and heavier alkanes acting as short-lived VOCs contributing to regional ozone formation. Methane emissions from the industry are also a forcing mechanism for climate change as methane is a potent greenhouse gas. Recent studies have highlighted a high variability and uncertainties in oil and natural gas emissions estimates in emissions inventories. Thus, accurately quantifying oil and natural gas emissions from the Eagle Ford Shale is necessary to assess the industry's impacts on climate forcing and regional air quality. We estimate oil and natural gas emissions in the Eagle Ford Shale using in situ ethane measurements along southwesterly trajectories from the Gulf of Mexico, dominantly during the summertime. Ethane enhancement within the drilling area is estimated by comparing ethane concentrations upwind of the shale, near the Texas coastline, to downwind measurements in the San Antonio Metropolitan Area, Odessa, and Amarillo. Upwind ethane observations indicate low background levels entering Texas in the Gulf of Mexico air masses. Significant ethane enhancement is observed between the coast and San Antonio, and is attributed to oil and natural gas operations due to the concurrent enhancements of heavier alkanes. Using typical boundary layer depths and presuming homogenous emissions across the Eagle Ford shale area, the observed ethane enhancements are used to extrapolate an estimate of oil and natural gas industry emissions in the Eagle Ford. As oil and natural gas production in the area is projected to grow rapidly over the coming years, the impacts of these emissions on regional air quality will need to be thoroughly studied.

  18. Short-chain alkane cycling in deep Gulf of Mexico cold-seep sediments

    NASA Astrophysics Data System (ADS)

    Sibert, R.; Joye, S. B.; Hunter, K.

    2015-12-01

    Mixtures of light hydrocarbon gases are common in deep Gulf of Mexico cold-seep sediments, and are typically dissolved in pore fluids, adsorbed to sediment particles, trapped in methane ice, or as free gas. The dominant component in these natural gas mixtures is usually methane (>80% C1), but ethane (C2) and propane (C3) are nearly always present in trace amounts (<1% total). The processes that control the concentration and isotopic signature of these gases in sediments are well explained for methane, but the controls for C2/C3 cycling are still a relative mystery. Methane production proceeds in deep anoxic sediments by either 1) thermocatalytic cracking of fossil organic matter, or 2) as a direct product of microbial metabolism, i.e. methanogenesis. In surface sediments, it appears that both microbial consumption and chemical deposition of methane (i.e. as methane clathrate) ensures that >95% of the methane produced at depth never reaches the water column. Production of C1 and C2 in deep-sea sediments has been historically attributed only to thermocatalytic processes, though limited data suggests production of C2/C3 compounds through the activity of archaea at depth. Furthermore, carbon isotopic data on ethane and propane from deep cores of Gulf of Mexico sediments suggest alkanogenesis at >3 m depth in the sediment column and alkane oxidation in uppermost oxidant-rich sediments. Additional studies have also isolated microorganisms capable of oxidizing ethane and propane in the laboratory, but field studies of microbial-driven dynamics of C2/C3 gases in cold-seep sediments are rare. Here, we present the results of a series of incubation experiments using sediment slurries culled from surface sediments from one of the most prolific natural oil and gas seeps in the Gulf of Mexico. Rates of alkane oxidation were measured under a variety of conditions to assess the surface-driven microbial controls on C2/C3 cycling in cold-seep environments. Such microbial processes are important in terms of the possible 'oxidative overprinting' of alkane isotopic signatures produced at depth, possibly obscuring typical microbial isotopic signals.

  19. Numerical simulation of injection process of warm carbon dioxide into layer saturated with methane and its hydrate

    NASA Astrophysics Data System (ADS)

    Khasanov, M. K.; Stolpovsky, M. V.; Gimaltdinov, I. K.

    2018-05-01

    In this article, in a flat-one-dimensional approximation, a mathematical model is presented for injecting warm carbon dioxide into a methane hydrate formation of finite length. It is established that the model of formation of hydrate of carbon dioxide in the absence of an area saturated with methane and water, under certain parameters, leads to thermodynamic contradiction. The mathematical model of carbon dioxide injection with formation of the region saturated with methane and water is constructed.

  20. The MOYA aircraft campaign: First measurements of methane, ethane and C-13 isotopes from West African biomass burning and other regional sources using the UK FAAM aircraft

    NASA Astrophysics Data System (ADS)

    Allen, Grant; Pitt, Joseph; Lee, James; Hopkins, James; Young, Stuart; Bauguitte, Stéphane; Gallagher, Martin; Fisher, Rebecca; Lowry, David; Nisbet, Euan

    2017-04-01

    Global methane concentrations continue to rise due to an imbalance between sources and sinks. There remains little consensus on the relative components of the manifold source types and their geographical origin. The Global Methane Budget and Yearly Assessments (MOYA) project is tasked with better characterising the global methane budget through an augmented global measurement and modelling programme. As part of MOYA, the UK's Facility for Airborne Atmospheric Measurement (FAAM), will fly four campaigns based out of West Africa and Ascension Island in the period 2017-2019, to focus on the important role of tropical sources. The first of these, to be conducted in late February 2017, will focus on the biomass burning season in West Africa. This paper will present the plan for future FAAM MOYA campaigns and report on our first aircraft data gathered in the West African region. The new addition of an interband cascade laser spectrometer to the FAAM aircraft, flown in this campaign for the first time, promises to provide the first real-time, continuous, and simultaneous, airborne measurements of methane, ethane and methane C-13 isotopologues. Together, these measurements, when interpreted in combination with other trace gases and aerosol measured on the aircraft, will serve as case studies to inform modelling of regional and global fluxes through their isotopic fingerprints.

  1. Clathrate hydrate stability models for Titan: implications for a global subsurface ocean

    NASA Astrophysics Data System (ADS)

    Basu Sarkar, D.; Elwood Madden, M.

    2013-12-01

    Titan is the only planetary body in the solar system, apart from the Earth, with liquid at its surface. Titan's changing rotational period suggests that a global subsurface ocean decouples the icy crust from the interior. Several studies predict the existence of such an internal ocean below an Ice I layer, ranging in depth between a few tens of kilometers to a few hundreds of kilometers, depending on the composition of the icy crust and liquid-ocean. While the overall density of Titan is well constrained, the degree of differentiation within the interior is unclear. These uncertainties lead to poor understanding of the volatile content of the moon. However, unlike other similar large icy moons like Ganymede and Callisto, Titan has a thick nitrogen atmosphere, with methane as the second most abundant constituent - 5% near the surface. Titan's atmosphere, surface, and interior are likely home to various compounds such as C2H6, CO2, Ar, N2 and CH4, capable of forming clathrate hydrates. In addition, the moon has low temperature and low-to-high pressure conditions required for clathrate formation. Therefore the occurrence of extensive multicomponent hydrates may effect the composition of near-surface materials, the subsurface ocean, as well as the atmosphere. This work uses models of hydrate stability for a number of plausible hydrate formers including CH4, C2H6, CH4 + C2H6 and CH4 + NH3, and equilibrium geothermal gradients for probable near-surface materials to delineate the lateral and vertical extent of clathrate hydrate stability zones for Titan. By comparing geothermal gradients with clathrate stability fields for these systems we investigate possible compositions of Titan's global subsurface ocean. Preliminary model results indicate that ethane hydrates or compound hydrates of ethane and methane could be destabilized within the proposed depth range of the internal ocean, while methane/ammonia or pure methane hydrates may not be affected. Therefore, ethane or ethane-methane clathrates may be a major component of Titan's icy shell. Modeled geothermal gradients and stability fields of possible clathrate formers with three different scenarios for an internal ocean from the recent literature. Geothermal gradients obtained from thermal conductivity and density representing water ice and pure CH4-C2H6 hydrate. Clathrate stability field determined using HYDOFF and recent publications of NH3 clathrate stability.

  2. Hydrocarbon gas seeps of the convergent Hikurangi margin, North Island, New Zealand

    USGS Publications Warehouse

    Kvenvolden, K.A.; Pettinga, J.R.

    1989-01-01

    Two hydrocarbon gas seeps, located about 13 km apart, have distinctive molecular and isotopic compositions. These seeps occur within separate tectonic melange units of narrow parallel trending and structurally complex zones with incorporated upper Cretaceous and Palaeogene passive continental margin deposits which are now compressively deformed and imbricated along the convergent Hikurangi margin of North Island, New Zealand. At Brookby Station within the Coastal High, the seeping hydrocarbon gas has a methane/ethane ratio of 48 and ??13C and ??D values of methane of -45.7 and -188???, respectively (relative to the PDB and SMOW standards). Within the complex core of the Elsthorpe Anticline at Campbell Station seep, gas has a methane/ethane ratio of about 12000, and the methane has ??13C and ??D values of -37.4 and -170???, respectively. The source of the gases cannot be positively identified, but the gases probably originate from the thermal decomposition of organic matter in tectonically disturbed upper Cretaceous and/or lower Tertiary sedimentary rocks of passive margin affinity and reach the surface by migration along thrust faults associated with tectonic melange. The geochemical differences between the two gases may result from differences in burial depths of similar source sediment. ?? 1989.

  3. Emissions from cold heavy oil production with sands (CHOPS) facilities in Alberta, Canada

    NASA Astrophysics Data System (ADS)

    Roscioli, J. R.; Herndon, S. C.; Yacovitch, T. I.; Knighton, W. B.; Zavala-Araiza, D.; Johnson, M. R.; Tyner, D. R.

    2017-12-01

    Cold heavy oil production with sands (CHOPS) is generally characterized as a pump driven oil extraction method producing a mixture of sand, water, and heavy oil to heated liquid storage tanks. In addition to fluids, CHOPS sites also produce solution gas, primarily composed of methane, through the well annulus. Depending on formation and well production characteristics, large volumes of this solution gas are frequently vented to the atmosphere without flaring or conservation. To better understand these emission we present measurements of methane, ethane, propane and aromatic emission rates from CHOPS sites using dual tracer flux ratio methodology. The use of two tracers allowed on-site emission sources to be accurately identified and in one instance indicated that the annular vent was responsible for >75% of emissions at the facility. Overall, a measurement survey of five CHOPS sites finds that the methane emissions are in general significantly under-reported by operators. This under-reporting may arise from uncertainties associated with measured gas-to-oil ratios upon which the reported vent volume is based. Finally, measurements of ethane, propane and aromatics from these facilities indicates surprisingly low non-methane hydrocarbon content.

  4. Spatial variability in nitrous oxide and methane emissions from beef cattle feedyard pen surfaces

    USDA-ARS?s Scientific Manuscript database

    Greenhouse gas emissions from beef cattle feedlots include enteric carbon dioxide and methane, and manure-derived methane, nitrous oxide and carbon dioxide. Enteric methane comprises the largest portion of the greenhouse gas footprint of beef cattle feedyards. For the manure component, methane is th...

  5. Methane and carbon dioxide emissions from Shan-Chu-Ku landfill site in northern Taiwan.

    PubMed

    Hegde, Ullas; Chang, Tsan-Chang; Yang, Shang-Shyng

    2003-09-01

    To investigate the methane and carbon dioxide emissions from landfill, samples were taken of material up to 5 years old from Shan-Chu-Ku landfill located in the northern part of Taiwan. Atmospheric concentrations of carbon dioxide, methane and nitrous oxide ranged from 310 to 530, 2.64 to 20.16 and 0.358 to 1.516 ppmv with the measurement of gas-type open-path Fourier transform infra-red (FTIR) spectroscopy during February 1998 to March 2000, respectively. Average methane emission rate was 13.17, 65.27 and 0.99 mgm(-2)h(-1) measured by the gas chromatography chamber method in 1-2, 2-3 and 5 year-old landfill, respectively. Similarly, average carbon dioxide emission rate was 93.70, 314.60 and 48.46 mgm(-2)h(-1), respectively. About 2-3 year-old landfill had the highest methane and carbon dioxide emission rates among the tested areas, while 5 year-old landfill was the least. Methane emission rate at night in most tested locations was higher than that in the daytime. Total amount of methane and carbon dioxide emission from this landfill was around 171 and 828 ton in 1999, respectively.

  6. PREPARATION OF PLUTONIUM TRIFLUORIDE

    DOEpatents

    Burger, L.L.; Roake, W.E.

    1961-07-11

    A process of producing plutonium trifluoride by reacting dry plutonium(IV) oxalate with chlorofluorinated methane or ethane at 400 to 450 deg C and cooling the product in the absence of oxygen is described.

  7. The Composition of Titan's Lower Atmosphere and Simple Surface Volatiles as Measured by the Cassini-Huygens Probe Gas Chromatograph Mass Spectrometer Experiment

    NASA Technical Reports Server (NTRS)

    Niemann, H. B.; Atreya, S. K.; Demick, J. E.; Gautier, D.; Haberman, J. A.; Harpold, D. N.; Kasprzak, W. T.; Lunine, J. I.; Owen, T. C.; Raulin, F.

    2010-01-01

    The Cassini-Huygens Probe Gas Chromatograph Mass Spectrometer (GCMS) determined the composition of the Titan atmosphere from 140km altitude to the surface. After landing, it returned composition data of gases evaporated from the surface. Height profiles of molecular nitrogen (N2), methane (CH4) and molecular hydrogen (H2) were determined. Traces were detected on the surface of evaporating methane, ethane (C2H6), acetylene (C2H2), cyanogen (C2N2) and carbon dioxide (CO2). The methane data showed evidence that methane precipitation occurred recently. The methane mole fraction was (1.48+/-0.09) x 10(exp -2) in the lower stratosphere (139.8 km to 75.5 km) and (5.65+/-0.18) x 10(exp -2) near the surface (6.7 km to the surface). The molecular hydrogen mole fraction was (1.01+/-0.16) x 10(exp -3) in the atmosphere and (9.90+/-0.17) x 10(exp -4) on the surface. Isotope ratios were 167.7+/-0.6 for N-14/N-15 in molecular nitrogen, 91.1+/-1.4 for C-12/C-13 in methane and (1.35+/-0.30) x 10(exp -4) for D/H in molecular hydrogen. The mole fractions of Ar-36 and radiogenic Ar-40 are (2.1+/-0.8) x 10(exp -7) and (3.39 +/-0.12) x 10(exp -5) respectively. Ne-22 has been tentatively identified at a mole fraction of (2.8+/-2.1) x 10(exp -7) Krypton and xenon were below the detection threshold of 1 x 10(exp -8) mole fraction. Science data were not retrieved from the gas chromatograph subsystem as the abundance of the organic trace gases in the atmosphere and on the ground did not reach the detection threshold. Results previously published from the GCMS experiment are superseded by this publication.

  8. Mars methane engine

    NASA Technical Reports Server (NTRS)

    Bui, Hung; Coletta, Chris; Debois, Alain

    1994-01-01

    The feasibility of an internal combustion engine operating on a mixture of methane, carbon dioxide, and oxygen has been verified by previous design groups for the Mars Methane Engine Project. Preliminary stoichiometric calculations examined the theoretical fuel-air ratios needed for the combustion of methane. Installation of a computer data acquisition system along with various ancillary components will enable the performance of the engine, running on the described methane mixture, to be optimized with respect to minimizing excess fuel. Theoretical calculations for stoichiometric combustion of methane-oxygen-carbon dioxide mixtures yielded a ratio of 1:2:4.79 for a methane-oxygen-carbon dioxide mixture. Empirical data shows the values to be closer to 1:2.33:3.69 for optimum operation.

  9. National Gas Hydrate Program Expedition 01 offshore India; gas hydrate systems as revealed by hydrocarbon gas geochemistry

    USGS Publications Warehouse

    Lorenson, Thomas; Collett, Timothy S.

    2018-01-01

    The National Gas Hydrate Program Expedition 01 (NGHP-01) targeted gas hydrate accumulations offshore of the Indian Peninsula and along the Andaman convergent margin. The primary objectives of coring were to understand the geologic and geochemical controls on the accumulation of methane hydrate and their linkages to underlying petroleum systems. Four areas were investigated: 1) the Kerala-Konkan Basin in the eastern Arabian Sea, 2) the Mahanadi and 3) Krishna-Godavari Basins in the western Bay of Bengal, and 4) the Andaman forearc Basin in the Andaman Sea.Upward flux of methane at three of the four of the sites cored during NGHP-01 is apparent from the presence of seafloor mounds, seismic evidence for upward gas migration, shallow sub-seafloor geochemical evidence of methane oxidation, and near-seafloor gas composition that resembles gas from depth.The Kerala-Konkan Basin well contained only CO2 with no detectable hydrocarbons suggesting there is no gas hydrate system here. Gas and gas hydrate from the Krishna-Godavari Basin is mainly microbial methane with δ13C values ranging from −58.9 to −78.9‰, with small contributions from microbial ethane (−52.1‰) and CO2. Gas from the Mahanadi Basin was mainly methane with lower concentrations of C2-C5 hydrocarbons (C1/C2 ratios typically >1000) and CO2. Carbon isotopic compositions that ranged from −70.7 to −86.6‰ for methane and −62.9 to −63.7‰ for ethane are consistent with a microbial gas source; however deeper cores contained higher molecular weight hydrocarbon gases suggesting a small contribution from a thermogenic gas source. Gas composition in the Andaman Basin was mainly methane with lower concentrations of ethane to isopentane and CO2, C1/C2 ratios were mainly >1000 although deeper samples were <1000. Carbon isotopic compositions range from −65.2 to −80.7‰ for methane, −53.1 to −55.2‰ for ethane is consistent with mainly microbial gas sources, although one value recorded of −35.4‰ for propane suggests a thermogenic source. Gas hydrate accumulations in the Krishna-Godavari and Mahanadi Basins are the result of a microbially sourced gas hydrate system. The system is enhanced by the migration of microbial gas from surrounding areas through pathways including high-porosity delta sands, shale diapirism, faulting and folding of sediment due to the local processes associated with rapid sediment deposition, sediment overpressure, and the recycling of methane from a rapidly upward moving gas hydrate stability zone. The gas hydrate system in the Andaman Basin is less well constrained due to lack of exploration and occurs in a forearc basin. Each of these hydrate-bearing systems overlies and is likely supported by the presence and possible migration of gas from deeper gas-prone petroleum systems currently generating thermogenic hydrocarbons at much greater depths.

  10. An Improved Cryogen for Plunge Freezing

    PubMed Central

    Tivol, William F.; Briegel, Ariane; Jensen, Grant J.

    2011-01-01

    The use of an alkane mixture that remains liquid at 77 K to freeze specimens has advantages over the use of a pure alkane that is solid at 77 K. It was found that a mixture of methane and ethane did not give a cooling rate adequate to produce vitreous ice, but a mixture of propane and ethane did result in vitreous ice. Furthermore, the latter mixture produced less damage to specimens mounted on a very thin, fragile holey carbon substrate. PMID:18793481

  11. Parametric performance of circumferentially grooved heat pipes with homogeneous and graded-porosity slab wicks at cryogenic temperatures. [methane and ethane working fluids

    NASA Technical Reports Server (NTRS)

    Groll, M.; Pittman, R. B.; Eninger, J. E.

    1976-01-01

    A recently developed, potentially high-performance nonarterial wick was extensively tested. This slab wick has an axially varying porosity which can be tailored to match the local stress imposed on the wick. The purpose of the tests was to establish the usefulness of the graded-porosity slab wick at cryogenic temperatures between 110 and 260 K, with methane and ethane as working fluids. For comparison, a homogeneous (i.e., uniform porosity) slab wick was also tested. The tests included: maximum heat pipe performance as a function of fluid inventory, maximum performance as a function of operating temperature, maximum performance as a function of evaporator elevation, and influence of slab wick orientation on performance. The experimental data were compared with theoretical predictions obtained with the GRADE computer program.

  12. Photodissociation of cyanoacetylene: Application to the atmospheric chemistry of Titan

    NASA Technical Reports Server (NTRS)

    Clarke, David W.; Ferris, James P.

    1995-01-01

    The quantum yield and reaction threshold for the photochemical dissociation of cyanoacetylene into a hydrogen atom and the cyanoethynyl radical have been determined. The quantum yield at 185 nm is approximately 0.09. The threshold is approximately 240 nm. Combination of this data with literature values shows that production of excited-state cyanoacetylene is the major primary process resulting from irradiation between 185 and 254 nm. Also determined are the relative rate constants for the abstraction of a hydrogen atom from hydrogen, methane, and ethane by the cyanoethynyl radical (k(H2):k(CH4):k(C2H6) = 1:9.3:63). Implications of these results for the proposal that hydrogen abstraction plays an important role in the conversion of methane to ethane and in the protection of unsaturated compounds from photoconsumption in the atmosphere of Titan are discussed.

  13. Astrobiological Implications of Titan Tholin in Methane Lakes

    NASA Astrophysics Data System (ADS)

    Khare, Bishun N.; McKay, C. P.; McPherson, S.; Cruikshank, D.; Nna-Mvondo, D.; Sekine, Y.

    2010-10-01

    We report here on our ongoing research in the Laboratory for Planetary Studies at NASA Ames Research Center dedicated to determine the degree of solubility of Titan tholin in the methane-ethane lakes. Our work is also directed toward confirming the presence of any astrobiologically significant molecules via hydrolysis and pyrolysis of a simulated lake sample. Our previous work conducted at Cornell University and subsequently in the Laboratory for Planetary Studies at NASA Ames Research Center has established that Titan tholin produces amino acids (Khare et al. Icarus 1986) on hydrolysis, and many compounds including adenine on pyrolysis (Khare et al. Adv. Space Res. 1984). Also, our previous work by Thompson et al. (Icarus 1991) has clearly indicated that when energy is supplied to Titan's atmospheric composition (methane and nitrogen), tholin results from hundreds of contemporary compounds, including highly reactive compounds such as azides and isocyanides. Cassini showed that photolysis of methane produces benzene and many polycyclic aromatic hydrocarbons, along with compounds with very high molecular weights (up to 10000 amu), resulting from the photolytic reactions of CH4 with nitrogen. These heavy aerosols, termed "tholins” by Sagan and Khare (Nature 1979), are also synthesized when Titan intercepts charged particles from the magnetosphere of Saturn. Tholins resulting from both of these syntheses eventually descend to the surface of Titan, where some quantity collects in the methane-ethane lakes. This research is supported by a grant from Planetary Atmospheres.

  14. A comparison between Peng-Robinson and Soave-Redlich-Kwong cubic equations of state from modification perspective

    NASA Astrophysics Data System (ADS)

    Ghanbari, Mehdi; Ahmadi, Mahdi; Lashanizadegan, Asghar

    2017-06-01

    The Cubic Equations of State (CEOSs) are the most important tools in PVT calculations due to their simplicity in use and their extrapolative abilities to condition well outside their correlation ranges. Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK) are most successful in the CEOSs which have repeatedly been modified in order to improve their accuracy in wider ranges of temperature and pressure. Unfortunately, most of modifications carried out on these EOSs have no adequate justification for selecting either of these as the basic starting point for the modifications. In this paper, PR and SRK EOSs were critically compared with each other using some new features of their subcritical and supercritical results. For this purpose, the CEOSs were assessed using comprehensive tests of the PVT calculations in the vapor-liquid equilibrium (for pure hydrocarbons over a wide range of acentric factor values: Methane, Ethane Propane, Butane, Heptane and Nonane) and Joule-Thomson Inversion Curves' (JTICs) predictions (for compounds which have reliable JTICs data: Methane, Ethane, Ethylene, Nitrogen, Oxygen, Argon and Carbon dioxide) in subcritical and supercritical regions, respectively. The results indicated that the PR EOS by using any of realistic α-function forms will never be able to accurately predict the JTICs in full span. On the other hand, the subcritical results revealed that the great success of the PR CEOS in predicting liquid phase density is only due to its function in shifting the results of the SRK CEOS to the lower values with the same curve trend. In addition, the Patel and Teja's (PT) EOS, has been reevaluated and the results showed that most of the defects of PR EOS still remain. This article suggests that in order to develop CEOSs, the original SRK EOS is a better candidate than original and alternative forms of PR EOS.

  15. Real-time drilling mud gas monitoring for qualitative evaluation of hydrocarbon gas composition during deep sea drilling in the Nankai Trough Kumano Basin.

    PubMed

    Hammerschmidt, Sebastian B; Wiersberg, Thomas; Heuer, Verena B; Wendt, Jenny; Erzinger, Jörg; Kopf, Achim

    2014-01-01

    Integrated Ocean Drilling Program Expedition 338 was the second scientific expedition with D/V Chikyu during which riser drilling was conducted as part of the Nankai Trough Seismogenic Zone Experiment. Riser drilling enabled sampling and real-time monitoring of drilling mud gas with an onboard scientific drilling mud gas monitoring system ("SciGas"). A second, independent system was provided by Geoservices, a commercial mud logging service. Both systems allowed the determination of (non-) hydrocarbon gas, while the SciGas system also monitored the methane carbon isotope ratio (δ(13)CCH4). The hydrocarbon gas composition was predominated by methane (> 1%), while ethane and propane were up to two orders of magnitude lower. δ(13)CCH4 values suggested an onset of thermogenic gas not earlier than 1600 meter below seafloor. This study aims on evaluating the onboard data and subsequent geological interpretations by conducting shorebased analyses of drilling mud gas samples. During shipboard monitoring of drilling mud gas the SciGas and Geoservices systems recorded up to 8.64% and 16.4% methane, respectively. Ethane and propane concentrations reached up to 0.03 and 0.013%, respectively, in the SciGas system, but 0.09% and 0.23% in the Geoservices data. Shorebased analyses of discrete samples by gas chromatography showed a gas composition with ~0.01 to 1.04% methane, 2 - 18 ppmv ethane, and 2 - 4 ppmv propane. Quadruple mass spectrometry yielded similar results for methane (0.04 to 4.98%). With δD values between -171‰ and -164‰, the stable hydrogen isotopic composition of methane showed little downhole variability. Although the two independent mud gas monitoring systems and shorebased analysis of discrete gas sample yielded different absolute concentrations they all agree well with respect to downhole variations of hydrocarbon gases. The data point to predominantly biogenic methane sources but suggest some contribution from thermogenic sources at depth, probably due to mixing. In situ thermogenic gas production at depths shallower 2000 mbsf is unlikely based on in situ temperature estimations between 81°C and 85°C and a cumulative time-temperature index of 0.23. In conclusion, the onboard SciGas data acquisition helps to provide a preliminary, qualitative evaluation of the gas composition, the in situ temperature and the possibility of gas migration.

  16. Measuring ethane and acetylene in Antarctic ice cores to quantify long-term hydrocarbon emissions from tropical fires

    NASA Astrophysics Data System (ADS)

    Nicewonger, M. R.; Aydin, M.; Prather, M. J.; Saltzman, E. S.

    2017-12-01

    This study examines ethane (C2H6) and acetylene (C2H2) in polar ice cores in order to reconstruct variations in the atmospheric levels of these trace gases over the past 2,000 years. Both of these non-methane hydrocarbons are released from fossil fuel, biofuel, and biomass burning. Ethane, but not acetylene, is also emitted from natural geologic outgassing of hydrocarbons. In an earlier study, we reported ethane levels in Greenland and Antarctic ice cores showing roughly equal contributions from biomass burning and geologic emissions to preindustrial atmospheric ethane levels (Nicewonger et al., 2016). Here we introduce acetylene as an additional constraint to better quantify preindustrial variations in the emissions from these natural hydrocarbon sources. Here we present 30 new measurements of ethane and acetylene from the WDC-06A ice core from WAIS Divide and the newly drilled South Pole ice core (SPICECORE). Ethane results display a gradual decline from peak levels of 110 ppt at 1400 CE to a minimum of 60-80 ppt during 1700-1875 CE. Acetylene correlates with ethane (r2 > 0.4), dropping from peak levels of 35 ppt at 1400 CE to 15-20 ppt at 1875 CE. The covariance between the two trace gases implies that the observed changes are likely caused by decreasing emissions from low latitude biomass burning. We will discuss results from chemical transport modeling and sensitivity tests and the implications for the preindustrial ethane and acetylene budgets.

  17. 40 CFR 60.610 - Applicability and designation of affected facility.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... numerical emission limits in these standards are expressed in terms of total organic compounds (TOC), measured as TOC minus methane and ethane. This emission limit reflects the performance of BDT. [55 FR 26922...

  18. Vast Ligeia Mare in False Color

    NASA Image and Video Library

    2013-05-22

    Ligeia Mare, shown here in a false color image from NASA Cassini mission, is the second largest known body of liquid on Saturn moon Titan. It is filled with liquid hydrocarbons, such as ethane and methane.

  19. Methyl Radicals in Oxidative Coupling of Methane Directly Confirmed by Synchrotron VUV Photoionization Mass Spectroscopy

    PubMed Central

    Luo, Liangfeng; Tang, Xiaofeng; Wang, Wendong; Wang, Yu; Sun, Shaobo; Qi, Fei; Huang, Weixin

    2013-01-01

    Gas-phase methyl radicals have been long proposed as the key intermediate in catalytic oxidative coupling of methane, but the direct experimental evidence still lacks. Here, employing synchrotron VUV photoionization mass spectroscopy, we have directly observed the formation of gas-phase methyl radicals during oxidative coupling of methane catalyzed by Li/MgO catalysts. The concentration of gas-phase methyl radicals correlates well with the yield of ethylene and ethane products. These results lead to an enhanced fundamental understanding of oxidative coupling of methane that will facilitate the exploration of new catalysts with improved performance. PMID:23567985

  20. More feed efficient sheep produce less methane and carbon dioxide when eating high-quality pellets.

    PubMed

    Paganoni, B; Rose, G; Macleay, C; Jones, C; Brown, D J; Kearney, G; Ferguson, M; Thompson, A N

    2017-09-01

    The Australian sheep industry aims to increase the efficiency of sheep production by decreasing the amount of feed eaten by sheep. Also, feed intake is related to methane production, and more efficient (low residual feed intake) animals eat less than expected. So we tested the hypothesis that more efficient sheep produce less methane by investigating the genetic correlations between feed intake, residual feed intake, methane, carbon dioxide, and oxygen. Feed intake, methane, oxygen, and carbon dioxide were measured on Merino ewes at postweaning (1,866 at 223 d old), hogget (1,010 sheep at 607 d old), and adult ages (444 sheep at 1,080 d old). Sheep were fed a high-energy grower pellet ad libitum for 35 d. Individual feed intake was measured using automated feeders. Methane was measured using portable accumulation chambers up to 3 times during this feed intake period. Heritabilities and phenotypic and genotypic correlations between traits were estimated using ASReml. Oxygen (range 0.10 to 0.20) and carbon dioxide (range 0.08 to 0.28) were generally more heritable than methane (range 0.11 to 0.14). Selecting to decrease feed intake or residual feed intake will decrease methane (genetic correlation [] range 0.76 to 0.90) and carbon dioxide ( range 0.65 to 0.96). Selecting to decrease intake ( range 0.64 to 0.78) and methane ( range 0.81 to 0.86) in sheep at postweaning age would also decrease intake and methane in hoggets and adults. Furthermore, selecting for lower residual feed intake ( = 0.75) and carbon dioxide ( = 0.90) in hoggets would also decrease these traits in adults. Similarly, selecting for higher oxygen ( = 0.69) in hoggets would also increase this trait in adults. Given these results, the hypothesis that making sheep more feed efficient will decrease their methane production can be accepted. In addition, carbon dioxide is a good indicator trait for feed intake because it has the highest heritability of the gas traits measured; is cheaper, faster, and easier to measure than feed intake and has strong phenotypic and genetic correlations with feed intake. Furthermore, selection for feed intake, feed efficiency, methane, and carbon dioxide can be done early in sheep at postweaning age or hoggets. This early selection reduces the generation interval for breeding, thereby increasing response to selection.

  1. 40 CFR 60.610 - Applicability and designation of affected facility.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... completed, but not later than 60 days after achieving the maximum production rate at which the affected...), measured as TOC minus methane and ethane. This emission limit reflects the performance of BDT. [55 FR 26922...

  2. 40 CFR 60.660 - Applicability and designation of affected facility.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... maximum production rate at which the affected facility will be operated, or 180 days after the initial... less methane and ethane. This emission limit reflects the performance of BDT.] [55 FR 26942, June 29...

  3. 40 CFR 60.660 - Applicability and designation of affected facility.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... maximum production rate at which the affected facility will be operated, or 180 days after the initial... less methane and ethane. This emission limit reflects the performance of BDT.] [55 FR 26942, June 29...

  4. 40 CFR 60.610 - Applicability and designation of affected facility.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... completed, but not later than 60 days after achieving the maximum production rate at which the affected...), measured as TOC minus methane and ethane. This emission limit reflects the performance of BDT. [55 FR 26922...

  5. 40 CFR 60.610 - Applicability and designation of affected facility.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... completed, but not later than 60 days after achieving the maximum production rate at which the affected...), measured as TOC minus methane and ethane. This emission limit reflects the performance of BDT. [55 FR 26922...

  6. 40 CFR 60.610 - Applicability and designation of affected facility.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... completed, but not later than 60 days after achieving the maximum production rate at which the affected...), measured as TOC minus methane and ethane. This emission limit reflects the performance of BDT. [55 FR 26922...

  7. Looking Down on Lakes

    NASA Image and Video Library

    2014-04-07

    NASA Cassini spacecraft peers down though layers of haze to glimpse the lakes of Titan northern regions. Titan has a hydrological cycle similar to Earth, but instead of water, Titan lakes and seas are filled with liquid methane and ethane.

  8. Identifying Different Types of Catalysts for CO2 Reduction by Ethane through Dry Reforming and Oxidative Dehydrogenation.

    PubMed

    Porosoff, Marc D; Myint, Myat Noe Zin; Kattel, Shyam; Xie, Zhenhua; Gomez, Elaine; Liu, Ping; Chen, Jingguang G

    2015-12-14

    The recent shale gas boom combined with the requirement to reduce atmospheric CO2 have created an opportunity for using both raw materials (shale gas and CO2 ) in a single process. Shale gas is primarily made up of methane, but ethane comprises about 10 % and reserves are underutilized. Two routes have been investigated by combining ethane decomposition with CO2 reduction to produce products of higher value. The first reaction is ethane dry reforming which produces synthesis gas (CO+H2 ). The second route is oxidative dehydrogenation which produces ethylene using CO2 as a soft oxidant. The results of this study indicate that the Pt/CeO2 catalyst shows promise for the production of synthesis gas, while Mo2 C-based materials preserve the CC bond of ethane to produce ethylene. These findings are supported by density functional theory (DFT) calculations and X-ray absorption near-edge spectroscopy (XANES) characterization of the catalysts under in situ reaction conditions. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  9. Identifying different types of catalysts for CO 2 reduction by ethane through dry reforming and oxidative dehydrogenation

    DOE PAGES

    Marc D. Porosoff; Chen, Jingguang G.; Myint, Myat Noe Zin; ...

    2015-11-10

    In this study, the recent shale gas boom combined with the requirement to reduce atmospheric CO 2 have created an opportunity for using both raw materials (shale gas and CO 2) in a single process. Shale gas is primarily made up of methane, but ethane comprises about 10 % and reserves are underutilized. Two routes have been investigated by combining ethane decomposition with CO 2 reduction to produce products of higher value. The first reaction is ethane dry reforming which produces synthesis gas (CO+H 2). The second route is oxidative dehydrogenation which produces ethylene using CO 2 as a softmore » oxidant. The results of this study indicate that the Pt/CeO 2 catalyst shows promise for the production of synthesis gas, while Mo 2C-based materials preserve the C—C bond of ethane to produce ethylene. These findings are supported by density functional theory (DFT) calculations and X-ray absorption near-edge spectroscopy (XANES) characterization of the catalysts under in situ reaction conditions.« less

  10. Main-group compounds selectively oxidize mixtures of methane, ethane, and propane to alcohol esters.

    PubMed

    Hashiguchi, Brian G; Konnick, Michael M; Bischof, Steven M; Gustafson, Samantha J; Devarajan, Deepa; Gunsalus, Niles; Ess, Daniel H; Periana, Roy A

    2014-03-14

    Much of the recent research on homogeneous alkane oxidation has focused on the use of transition metal catalysts. Here, we report that the electrophilic main-group cations thallium(III) and lead(IV) stoichiometrically oxidize methane, ethane, and propane, separately or as a one-pot mixture, to corresponding alcohol esters in trifluoroacetic acid solvent. Esters of methanol, ethanol, ethylene glycol, isopropanol, and propylene glycol are obtained with greater than 95% selectivity in concentrations up to 1.48 molar within 3 hours at 180°C. Experiment and theory support a mechanism involving electrophilic carbon-hydrogen bond activation to generate metal alkyl intermediates. We posit that the comparatively high reactivity of these d(10) main-group cations relative to transition metals stems from facile alkane coordination at vacant sites, enabled by the overall lability of the ligand sphere and the absence of ligand field stabilization energies in systems with filled d-orbitals.

  11. Opposed Jet Burner Extinction Limits: Simple Mixed Hydrocarbon Scramjet Fuels vs Air

    NASA Technical Reports Server (NTRS)

    Pellett, Gerald L.; Vaden, Sarah N.; Wilson, Lloyd G.

    2007-01-01

    Opposed Jet Burner tools have been used extensively by the authors to measure Flame Strength (FS) of laminar non-premixed H2 air and simple hydrocarbon (HC) air counterflow diffusion flames at 1-atm. FS represents a strain-induced extinction limit based on air jet velocity. This paper follows AIAA-2006-5223, and provides new HC air FSs for global testing of chemical kinetics, and for characterizing idealized flameholding potentials during early scramjet-like combustion. Previous FS data included six HCs, pure and N2-diluted; and three HC-diluted H2 fuels, where FS decayed very nonlinearly as HC was added to H2, due to H-atom scavenging. This study presents FSs on mixtures of (candidate surrogate) HCs, some with very high FS ethylene. Included are four binary gaseous systems at 300 K, and a hot ternary system at approx. 600 K. The binaries are methane + ethylene, ethane + ethylene, methane + ethane, and methane + propylene. The first three also form two ternary systems. The hot ternary includes both 10.8 and 21.3 mole % vaporized n-heptane and full ranges of methane + ethylene. Normalized FS data provide accurate means of (1) validating, globally, chemical kinetics for extinction of non-premixed flames, and (2) estimating (scaling by HC) the loss of incipient flameholding in scramjet combustors. The n-heptane is part of a proposed baseline simulant (10 mole % with 30% methane + 60% ethylene) that mimics the ignition of endothermically cracked JP-7 like kerosene fuel, as suggested by Colket and Spadaccini in 2001 in their shock tube Scramjet Fuels Autoignition Study. Presently, we use FS to gauge idealized flameholding, and define HC surrogates. First, FS was characterized for hot nheptane + methane + ethylene; then a hot 36 mole % methane + 64% ethylene surrogate was defined that mimics FS of the baseline simulant system. A similar hot ethane + ethylene surrogate can also be defined, but it has lower vapor pressure at 300 K, and thus exhibits reduced gaseous capacity. The new FS results refine our earlier idealized reactivity scale that shows wide ranging (50 x) diameter-normalized FSs for various HCs. These range from JP-10 and methane to H2 air, which produces an exceptionally strong flame that agrees within approx. 1% of recent 2-D numerically simulations. Finally, we continue advocating the FS approach as more direct and fundamental, for assessing idealized scramjet flameholding potentials, than measurements of unstrained laminar burning velocity or blowout in a Perfectly Stirred Reactor.

  12. Hydrocarbon-Rich Groundwater above Shale-Gas Formations: A Karoo Basin Case Study.

    PubMed

    Eymold, William K; Swana, Kelley; Moore, Myles T; Whyte, Colin J; Harkness, Jennifer S; Talma, Siep; Murray, Ricky; Moortgat, Joachim B; Miller, Jodie; Vengosh, Avner; Darrah, Thomas H

    2018-03-01

    Horizontal drilling and hydraulic fracturing have enhanced unconventional hydrocarbon recovery but raised environmental concerns related to water quality. Because most basins targeted for shale-gas development in the USA have histories of both active and legacy petroleum extraction, confusion about the hydrogeological context of naturally occurring methane in shallow aquifers overlying shales remains. The Karoo Basin, located in South Africa, provides a near-pristine setting to evaluate these processes, without a history of conventional or unconventional energy extraction. We conducted a comprehensive pre-industrial evaluation of water quality and gas geochemistry in 22 groundwater samples across the Karoo Basin, including dissolved ions, water isotopes, hydrocarbon molecular and isotopic composition, and noble gases. Methane-rich samples were associated with high-salinity, NaCl-type groundwater and elevated levels of ethane, 4 He, and other noble gases produced by radioactive decay. This endmember displayed less negative δ 13 C-CH 4 and evidence of mixing between thermogenic natural gases and hydrogenotrophic methane. Atmospheric noble gases in the methane-rich samples record a history of fractionation during gas-phase migration from source rocks to shallow aquifers. Conversely, methane-poor samples have a paucity of ethane and 4 He, near saturation levels of atmospheric noble gases, and more negative δ 13 C-CH 4 ; methane in these samples is biogenic and produced by a mixture of hydrogenotrophic and acetoclastic sources. These geochemical observations are consistent with other basins targeted for unconventional energy extraction in the USA and contribute to a growing data base of naturally occurring methane in shallow aquifers globally, which provide a framework for evaluating environmental concerns related to unconventional energy development (e.g., stray gas). © 2018, National Ground Water Association.

  13. Use of propane as a quench gas in argon-filled proportional counters and comparison with other quench gases

    NASA Technical Reports Server (NTRS)

    Agrawal, P. C.; Ramsey, B. D.

    1988-01-01

    An experimental investigation of propane and six other quench gases was carried out in argon-filled proportional counters. The objective of the study was to find the best gas mixture for optimizing the gas gain and the energy resolution as well as to understand the role of the ionization potential of quench gases in determining these parameters. It was found that the best gas gains and energy resolutions are obtained with propane, ethane, and isobutane in that order. The ionization potentials of these three lie below the argon metastable potentials and have the lowest value of resonance defect compared to the other quench gases. The better results obtained with these mixtures can be explained by an increased ionization yield resulting from the Penning effect. Propylene and trans-2-butene give inferior performance compared to the above three gases. Methane and carbon dioxide, the most commonly used quench gases in the argon-filled detectors, provide the worst results.

  14. Airborne Quantification of Methane Emissions in the San Francisco Bay Area of California

    NASA Astrophysics Data System (ADS)

    Guha, A.; Newman, S.; Martien, P. T.; Young, A.; Hilken, H.; Faloona, I. C.; Conley, S.

    2017-12-01

    The Bay Area Air Quality Management District, the San Francisco Bay Area's air quality regulatory agency, has set a goal to reduce the region's greenhouse gas (GHG) emissions 80% below 1990 levels by 2050, consistent with the State of California's climate protection goal. The Air District maintains a regional GHG emissions inventory that includes emissions estimates and projections which influence the agency's programs and regulatory activities. The Air District is currently working to better characterize methane emissions in the GHG inventory through source-specific measurements, to resolve differences between top-down regional estimates (Fairley and Fischer, 2015; Jeong et al., 2016) and the bottom-up inventory. The Air District funded and participated in a study in Fall 2016 to quantify methane emissions from a variety of sources from an instrumented Mooney aircraft. This study included 40 hours of cylindrical vertical profile flights that combined methane and wind measurements to derive mass emission rates. Simultaneous measurements of ethane provided source-apportionment between fossil-based and biological methane sources. The facilities sampled included all five refineries in the region, five landfills, two dairy farms and three wastewater treatment plants. The calculated mass emission rates were compared to bottom-up rates generated by the Air District and to those from facility reports to the US EPA as part of the mandatory GHG reporting program. Carbon dioxide emission rates from refineries are found to be similar to bottom-up estimates for all sources, supporting the efficacy of the airborne measurement methodology. However, methane emission estimates from the airborne method showed significant differences for some source categories. For example, methane emission estimates based on airborne measurements were up to an order of magnitude higher for refineries, and up to five times higher for landfills compared to bottom-up methods, suggesting significant underestimation in the inventories and self-reported estimates. Future measurements over the same facilities will reveal if we have seasonal and process-dependent trends in emissions. This will provide a basis for rule making and for designing mitigation and control actions.

  15. Distribution and geochemical characterization of coalbed gases at excavation fields at natural analogue site area Velenje Basin, Slovenia

    NASA Astrophysics Data System (ADS)

    Kanduč, Tjaša; Žigon, Stojan; Grassa, Fausto; Sedlar, Jerneja; Zadnik, Ivo; Zavšek, Simon

    2016-04-01

    Unconventional gas resources, including coal bed methane and shale gas, are a growing part of the global energy mix, which has changed the economic and strategic picture for gas consuming and producing countries, including the USA, China and Australia that, together are responsible for around half the currently recoverable unconventional gas resources. However, CBM production was often hindered by low permeability and mineralization in cleats and fractures, necessitating the development of cost effective horizontal drilling and completion techniques. Geochemical and isotopic monitoring of coalbed gases at excavation fields in Velenje Basin started in year 2000, with the aim to obtain better insights into the origin of coalbed gases. Results from active excavation fields in the mining areas Pesje and Preloge in the year period 2014-2015 are presented in this study. Composition and isotopic composition of coalbed gases were determined with mass - spectrometric methods. The chemical (methane, carbon dioxide, nitrogen) and isotopic composition of carbon in methane and carbon dioxide in the Velenje Basin vary and depend on the composition of the source of coalbed gas before excavation, advancement of the working face, depth of the longwall face, pre-mining activity and newly mined activity. The basic gas components determined in excavation fields are carbon dioxide and methane. Knowledge of the stable isotope geochemistry of coal bed and shale gas and the related production water is essential to determine not only gas origins but also the dominant methanogenic pathway in the case of microbial gas. Concentrations of methane at active excavation fields are changing from 1.8 to 63.9 %, concentrations of carbon dioxide are changing from 36.1 to 98.2% and CDMI (Carbon Dioxide Methane Index) index from 0.2 to 100 %. Isotopic composition of carbon dioxide is changing from -11.0 to -1.9‰ , isotopic composition of methane from -71.8 to -43.3‰ , isotopic composition of deuterium in methane from -343.9 to -223.1‰ , respectively. Further, these characteristics of methane have been compared with those observed in other coal sedimentary basins worldwide. The isotopic compositions of carbon and hydrogen in methane in the excavation fields show its biogenic origin, while a high Carbon Dioxide Methane Index (CDMI index) indicates the bacterial and endogenic origin of carbon dioxide.

  16. Marine microbes rapidly adapt to consume ethane, propane, and butane within the dissolved hydrocarbon plume of a natural seep

    NASA Astrophysics Data System (ADS)

    Mendes, Stephanie D.; Redmond, Molly C.; Voigritter, Karl; Perez, Christian; Scarlett, Rachel; Valentine, David L.

    2015-03-01

    Simple hydrocarbon gases containing two to four carbons (ethane, propane, and butane) are among the most abundant compounds present in petroleum reservoirs, and are introduced into the ocean through natural seepage and industrial discharge. Yet little is known about the bacterial consumption of these compounds in ocean waters. To assess the timing by which microbes metabolize these gases, we conducted a three-phase study that tested and applied a radiotracer-based method to quantify the oxidation rates of ethane, propane, and butane in fresh seawater samples. Phase 1 involved the synthesis of tritiated ethane, propane, and butane using Grignard reagents and tritiated water. Phase 2 was a systematic assessment of experimental conditions, wherein the indigenous microbial community was found to rapidly oxidize ethane, propane, and butane. Phase 3 was the application of this tritium method near the Coal Oil Point seeps, offshore California. Spatial and temporal patterns of ethane, propane, and butane oxidation down current from the hydrocarbon seeps demonstrated that >99% of these gases are metabolized within 1.3 days following initial exposure. The oxidation of ethane outpaced oxidation of propane and butane with patterns indicating the microbial community responded to these gases by rapid adaptation or growth. Methane oxidation responded the slowest in plume waters. Estimates based on the observed metabolic rates and carbon mass balance suggest that ethane, propane, and butane-consuming microorganisms may transiently account for a majority of the total microbial community in these impacted waters.

  17. Facultative methanotrophs are abundant at terrestrial natural gas seeps.

    PubMed

    Farhan Ul Haque, Muhammad; Crombie, Andrew T; Ensminger, Scott A; Baciu, Calin; Murrell, J Colin

    2018-06-28

    Natural gas contains methane and the gaseous alkanes ethane, propane and butane, which collectively influence atmospheric chemistry and cause global warming. Methane-oxidising bacteria, methanotrophs, are crucial in mitigating emissions of methane as they oxidise most of the methane produced in soils and the subsurface before it reaches the atmosphere. Methanotrophs are usually obligate, i.e. grow only on methane and not on longer chain alkanes. Bacteria that grow on the other gaseous alkanes in natural gas such as propane have also been characterised, but they do not grow on methane. Recently, it was shown that the facultative methanotroph Methylocella silvestris grew on ethane and propane, other components of natural gas, in addition to methane. Therefore, we hypothesised that Methylocella may be prevalent at natural gas seeps and might play a major role in consuming all components of this potent greenhouse gas mixture before it is released to the atmosphere. Environments known to be exposed to biogenic methane emissions or thermogenic natural gas seeps were surveyed for methanotrophs. 16S rRNA gene amplicon sequencing revealed that Methylocella were the most abundant methanotrophs in natural gas seep environments. New Methylocella-specific molecular tools targeting mmoX (encoding the soluble methane monooxygenase) by PCR and Illumina amplicon sequencing were designed and used to investigate various sites. Functional gene-based assays confirmed that Methylocella were present in all of the natural gas seep sites tested here. This might be due to its ability to use methane and other short chain alkane components of natural gas. We also observed the abundance of Methylocella in other environments exposed to biogenic methane, suggesting that Methylocella has been overlooked in the past as previous ecological studies of methanotrophs often used pmoA (encoding the alpha subunit of particulate methane monooxygenase) as a marker gene. New biomolecular tools designed in this study have expanded our ability to detect, and our knowledge of the environmental distribution of Methylocella, a unique facultative methanotroph. This study has revealed that Methylocella are particularly abundant at natural gas seeps and may play a significant role in biogeochemical cycling of gaseous hydrocarbons.

  18. Automatic Carbon Dioxide-Methane Gas Sensor Based on the Solubility of Gases in Water

    PubMed Central

    Cadena-Pereda, Raúl O.; Rivera-Muñoz, Eric M.; Herrera-Ruiz, Gilberto; Gomez-Melendez, Domingo J.; Anaya-Rivera, Ely K.

    2012-01-01

    Biogas methane content is a relevant variable in anaerobic digestion processing where knowledge of process kinetics or an early indicator of digester failure is needed. The contribution of this work is the development of a novel, simple and low cost automatic carbon dioxide-methane gas sensor based on the solubility of gases in water as the precursor of a sensor for biogas quality monitoring. The device described in this work was used for determining the composition of binary mixtures, such as carbon dioxide-methane, in the range of 0–100%. The design and implementation of a digital signal processor and control system into a low-cost Field Programmable Gate Array (FPGA) platform has permitted the successful application of data acquisition, data distribution and digital data processing, making the construction of a standalone carbon dioxide-methane gas sensor possible. PMID:23112626

  19. Automatic carbon dioxide-methane gas sensor based on the solubility of gases in water.

    PubMed

    Cadena-Pereda, Raúl O; Rivera-Muñoz, Eric M; Herrera-Ruiz, Gilberto; Gomez-Melendez, Domingo J; Anaya-Rivera, Ely K

    2012-01-01

    Biogas methane content is a relevant variable in anaerobic digestion processing where knowledge of process kinetics or an early indicator of digester failure is needed. The contribution of this work is the development of a novel, simple and low cost automatic carbon dioxide-methane gas sensor based on the solubility of gases in water as the precursor of a sensor for biogas quality monitoring. The device described in this work was used for determining the composition of binary mixtures, such as carbon dioxide-methane, in the range of 0-100%. The design and implementation of a digital signal processor and control system into a low-cost Field Programmable Gate Array (FPGA) platform has permitted the successful application of data acquisition, data distribution and digital data processing, making the construction of a standalone carbon dioxide-methane gas sensor possible.

  20. Comparison of natural gases accumulated in Oligocene strata with hydrous pyrolysis gases from Menilite Shales of the Polish Outer Carpathians

    USGS Publications Warehouse

    Kotarba, M.J.; Curtis, John B.; Lewan, M.D.

    2009-01-01

    This study examined the molecular and isotopic compositions of gases generated from different kerogen types (i.e., Types I/II, II, IIS and III) in Menilite Shales by sequential hydrous pyrolysis experiments. The experiments were designed to simulate gas generation from source rocks at pre-oil-cracking thermal maturities. Initially, rock samples were heated in the presence of liquid water at 330 ??C for 72 h to simulate early gas generation dominated by the overall reaction of kerogen decomposition to bitumen. Generated gas and oil were quantitatively collected at the completion of the experiments and the reactor with its rock and water was resealed and heated at 355 ??C for 72 h. This condition simulates late petroleum generation in which the dominant overall reaction is bitumen decomposition to oil. This final heating equates to a cumulative thermal maturity of 1.6% Rr, which represents pre-oil-cracking conditions. In addition to the generated gases from these two experiments being characterized individually, they are also summed to characterize a cumulative gas product. These results are compared with natural gases produced from sandstone reservoirs within or directly overlying the Menilite Shales. The experimentally generated gases show no molecular compositions that are distinct for the different kerogen types, but on a total organic carbon (TOC) basis, oil prone kerogens (i.e., Types I/II, II and IIS) generate more hydrocarbon gas than gas prone Type III kerogen. Although the proportionality of methane to ethane in the experimental gases is lower than that observed in the natural gases, the proportionality of ethane to propane and i-butane to n-butane are similar to those observed for the natural gases. ??13C values of the experimentally generated methane, ethane and propane show distinctions among the kerogen types. This distinction is related to the ??13C of the original kerogen, with 13C enriched kerogen generating more 13C enriched hydrocarbon gases than kerogen less enriched in 13C. The typically assumed linear trend for ??13C of methane, ethane and propane versus their reciprocal carbon number for a single sourced natural gas is not observed in the experimental gases. Instead, the so-called "dogleg" trend, exemplified by relatively 13C depleted methane and enriched propane as compared to ethane, is observed for all the kerogen types and at both experimental conditions. Three of the natural gases from the same thrust unit had similar "dogleg" trends indicative of Menilite source rocks with Type III kerogen. These natural gases also contained varying amounts of a microbial gas component that was approximated using the ????13C for methane and propane determined from the experiments. These approximations gave microbial methane components that ranged from 13-84%. The high input of microbial gas was reflected in the higher gas:oil ratios for Outer Carpathian production (115-1568 Nm3/t) compared with those determined from the experiments (65-302 Nm3/t). Two natural gas samples in the far western part of the study area had more linear trends that suggest a different organic facies of the Menilite Shales or a completely different source. This situation emphasizes the importance of conducting hydrous pyrolysis on samples representing the complete stratigraphic and lateral extent of potential source rocks in determining specific genetic gas correlations. ?? 2009 Elsevier Ltd.

  1. Greenhouse Gas Fluxes at the Tablelands, NL, Canada: A Site of Active Serpentinization

    NASA Astrophysics Data System (ADS)

    Morrill, P. L.; Morrissey, L. S.; Cumming, E.

    2016-12-01

    Active sites of serpentinization have been proposed as sites for carbon capture and storage (CCS) projects. However, in addition to their ability to convert carbon dioxide to carbonate rock, sites of serpentinization also have the potential release methane, which is a more power greenhouse gas than carbon dioxide. Very little is known about the natural flux of carbon dioxide sequestered and methane released into the atmosphere from active sites of serpentinization. In this study we measured carbon dioxide, methane, and nitrous oxide gas fluxes at a pool of ultra-basic water discharging from serpentinized rock in Winterhouse Canyon, Gros Morne, Newfoundland. We found that the flux of methane released was 4.6 x 10-7 mol/m2/min and the carbon dioxide sequestered was 1.9 x 10-5 mol/m2/min, while the concentrations of nitrous oxide showed little change. Based on these fluxes we calculated predictive climate change parameters such as net radiative forcing and global warming potential which predicted that despite the methane being released the site still had an overall long-term atmospheric cooling effect based on the natural rate of carbon dioxide sequestration.

  2. Diffusion of gas mixtures in the sI hydrate structure

    NASA Astrophysics Data System (ADS)

    Waage, Magnus H.; Trinh, Thuat T.; van Erp, Titus S.

    2018-06-01

    Replacing methane with carbon dioxide in gas hydrates has been suggested as a way of harvesting methane, while at the same time storing carbon dioxide. Experimental evidence suggests that this process is facilitated if gas mixtures are used instead of pure carbon dioxide. We studied the free energy barriers for diffusion of methane, carbon dioxide, nitrogen, and hydrogen in the sI hydrate structure using molecular simulation techniques. Cage hops between neighboring cages were considered with and without a water vacancy and with a potential inclusion of an additional gas molecule in either the initial or final cage. Our results give little evidence for enhanced methane and carbon dioxide diffusion if nitrogen is present as well. However, the inclusion of hydrogen seems to have a substantial effect as it diffuses rapidly and can easily enter occupied cages, which reduces the barriers of diffusion for the gas molecules that co-occupy a cage with hydrogen.

  3. Chemical identifications of possible martian hot spots

    NASA Astrophysics Data System (ADS)

    Wong, A. S.; Atreya, S. K.; Renno, N. O.

    2003-04-01

    If the interpretation of certain Mars Global Surveyor images indicating recent ground water seepage and surface runoff (1) is correct, it may imply that Mars can still be active internally in some places from time to time, and outgassing of certain molecules from the interior could occur with or without the water seepage. Although there is no evidence of active volcanism on Mars today, ``localized'' outgassing sources, the ``hot spots'', may not be ruled out. If outgassing does occur somewhere on Mars, water, carbon dioxide, sulfur species, methane, and to a lesser extent, halogens, would be the likely molecules of outgassing, based on the terrestrial analogs. The sulfur species, methane and halogens have not been detected in the ``global'' observations of Mars. Considering the possibility of outgassing from some localized hot spots, we have developed a one-dimensional photochemical model (2) that includes methane (CH_4), sulfur dioxide (SO_2) and hydrogen sulfide (H_2S), starting with their current ``global average'' upper limits of, respectively, 0.02, 0.1 and 0.1 ppm at the surface, and then progressively increasing their abundances above possible hot spots. Halogens are neglected as they are a minor product of the terrestrial outgassing sources. We find that the introduction of methane into the martian atmosphere results in the formation of mainly formaldehyde, methyl alcohol (CH_3OH) and ethane (C_2H_6), whereas the introduction of the sulfur species produces mainly sulfur monoxide (SO) and sulfuric acid (H_2SO_4). In a relatively short time of an hour, ordinary convective processes alone can reduce the mixing ratios of outgassed species by factors of 10^4 -- 10^5 approximately 50 km from the source, and the time for spreading the source material more or less uniformly over the planet (with corresponding dilution factor of ˜10^8) would be approximately one year. Depending upon the flux of the outgassed molecules from possible hot spots, some of these species, especially CH_4, SO_2, H_2S, and perhaps CH_2O, may be detectable locally, either by remote sensing or in situ measurements. References: (1) Malin, M. C. and K. S. Edgett, Science 288, 2330, 2000; (2) Wong, A. S., S. K. Atreya, and Th. Encrenaz, J. Geophys. Res., in press, 2003.

  4. 30 CFR 75.388 - Boreholes in advance of mining.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... more than 1.0 percent methane, less than 19.5 percent oxygen, or harmful concentrations of carbon monoxide, carbon dioxide or other explosive, harmful or noxious gases; (2) Tests for methane, oxygen... and the mine workings; (3) The concentrations of methane, oxygen, carbon monoxide, and carbon dioxide...

  5. 30 CFR 75.388 - Boreholes in advance of mining.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... more than 1.0 percent methane, less than 19.5 percent oxygen, or harmful concentrations of carbon monoxide, carbon dioxide or other explosive, harmful or noxious gases; (2) Tests for methane, oxygen... and the mine workings; (3) The concentrations of methane, oxygen, carbon monoxide, and carbon dioxide...

  6. 30 CFR 75.388 - Boreholes in advance of mining.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... more than 1.0 percent methane, less than 19.5 percent oxygen, or harmful concentrations of carbon monoxide, carbon dioxide or other explosive, harmful or noxious gases; (2) Tests for methane, oxygen... and the mine workings; (3) The concentrations of methane, oxygen, carbon monoxide, and carbon dioxide...

  7. 30 CFR 75.388 - Boreholes in advance of mining.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... more than 1.0 percent methane, less than 19.5 percent oxygen, or harmful concentrations of carbon monoxide, carbon dioxide or other explosive, harmful or noxious gases; (2) Tests for methane, oxygen... and the mine workings; (3) The concentrations of methane, oxygen, carbon monoxide, and carbon dioxide...

  8. 30 CFR 75.388 - Boreholes in advance of mining.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... more than 1.0 percent methane, less than 19.5 percent oxygen, or harmful concentrations of carbon monoxide, carbon dioxide or other explosive, harmful or noxious gases; (2) Tests for methane, oxygen... and the mine workings; (3) The concentrations of methane, oxygen, carbon monoxide, and carbon dioxide...

  9. Chemicals and energy co-generation from direct hydrocarbons/oxygen proton exchange membrane fuel cell

    NASA Astrophysics Data System (ADS)

    Li, W. S.; Lu, D. S.; Luo, J. L.; Chuang, K. T.

    A proton exchange membrane fuel cell for chemicals and energy co-generation was set up with hydrocarbons ethane, propane and butane as fuels, and the electrochemical performance of the cell was studied by using linear potential sweep, alternating current impedance and gas chromatography. The cell performance can be improved to a great extent by increasing the platinum load in the catalyst, by treating the membrane with phosphoric acid and by elevating temperature. The improvement of cell performance by the increase of platinum load is ascribed to the increase of reaction sites for hydrocarbon oxidation, that by phosphoric acid treatment to the increase of proton conductivity in Nafion membrane, and that by elevating temperature to the improvement in thermodynamic as well as kinetic aspects. Only a small fraction of the hydrocarbon is converted to carbon dioxide in this cell during its power generation. The current efficiency is 5% for the conversion of ethane to carbon dioxide in the ethane/oxygen fuel cell with 20% carbon-supported platinum as catalyst and phosphoric acid-treated membrane as proton exchange membrane at 0.2 V, 80 °C and ambient pressure. The reaction activity of hydrocarbons at the anode is in the order of propane, butane and ethane. The possible chemicals produced from the cell were hydrocarbons with more than six carbons, which are inactive at the anode under cell conditions.

  10. GREENOUSE GASES FROM SMALL-SCALE COMBUSTION DEVICES IN DEVELOPING COUNTRIES, PHASE IIA. HOUSEHOLD STOVES IN INDIA

    EPA Science Inventory

    The report contains a systematic set of measurements of carbon dioxide (CO2), carbon monoxide, methane, total non-methane organic compounds, nitrous oxide, sulfur dioxide, nitrogen dioxide, and total suspended particulate emissions from the commonest combustion devices in the wor...

  11. Dissolved gasesous hydrocarbons in shallow groundwater of Lower Saxony, Germany - Revisited 2016

    NASA Astrophysics Data System (ADS)

    Schloemer, Stefan; Illing, Christian J.; Blumenberg, Martin; Oest, Johanna; Elbracht, Jörg

    2017-04-01

    Many concerns arise within the public and government/political institutions over potential groundwater contamination from deep drilling operations. For this reason we initiated a baseline study in 2014 on the distribution of dissolved methane, ethane and propane in shallow groundwater ( 1000 groundwater wells, Schloemer et al., 2016) of Lower Saxony, which includes the major petroleum and natural gas provinces in Germany. We observed a variation of dissolved methane concentration over 7 orders of magnitude (20 nl/l to 60 ml/l [v/v]). Methane delta13C compositions ranged from -110‰ to +25‰ vs VPDB, narrowly clustering around -70‰ at high concentrations but being increasingly more variable at lower concentrations (-40‰ to -80‰)). Most of the data are clearly indicative for methanogenic processes, samples unusually enriched in delta13C can best be explained by secondary methane oxidation. Although some general regional trend can be observed, results are highly variable within short lateral distances or within different aquifers/filter depths. Frequently ethane (27% of samples, median 50nl/l) and occasionally propane (8%, median 23nl/l) has been detected. Lacking the carbon isotope composition of these homologues and thus solely based on the extremely low concentrations and atypical ethane/propane ratios, these have been tentatively interpreted as ubiquitous microbial background. From the original 2014 sample set around 100 wells have been selected for consecutive testing through 2015. In spring 2016 a total number of 1100 wells have been sampled, 700 of which had already been part of the initial study, providing us with the unique opportunity to assess long term variations. The overall comparison of these 700 samples revealed only small relative variations in methane concentrations (mostly < ± 25%), although higher variations are common at concentrations less than 1 µl/l. Correspondingly the carbon isotopic composition of paired samples is quite stable (± 2‰)) for most of the samples ( 60%) but large discrepancies can be observed at low absolute concentrations (> ± 5‰ in 25% of samples). Minor variations could be related to uncertainties in laboratory analysis (± 10% in concentration, ± 0.5‰ delta13C). To which extent the small number of sampled groundwater with unusually high variations are indeed a result of a naturally occurring process (rapidly changing conditions or anthropogenic influence) is currently under investigation. However, applying different sampling conditions/procedures (i.e. different pumps, flow rates) had to be accepted during the course of the project and might be a reason as well. In any case our preliminary results point toward the necessity of repeated sampling (particularly in shallow unconfined aquifers) to account for possible natural variations and of strictly consistent sampling protocols when analyzing "non-conservative" dissolved gases. Reference Schloemer, S., Elbracht, J., Blumenberg, M. and Illing, C.J., 2016. Distribution and origin of dissolved methane, ethane and propane in shallow groundwater of Lower Saxony, Germany. Applied Geochemistry, 67: 118-132.

  12. The role of water in gas hydrate dissociation

    USGS Publications Warehouse

    Circone, S.; Stern, L.A.; Kirby, S.H.

    2004-01-01

    When raised to temperatures above the ice melting point, gas hydrates release their gas in well-defined, reproducible events that occur within self-maintained temperature ranges slightly below the ice point. This behavior is observed for structure I (carbon dioxide, methane) and structure II gas hydrates (methane-ethane, and propane), including those formed with either H2O- or D2O-host frameworks, and dissociated at either ambient or elevated pressure conditions. We hypothesize that at temperatures above the H2O (or D2O) melting point: (1) hydrate dissociation produces water + gas instead of ice + gas, (2) the endothermic dissociation reaction lowers the temperature of the sample, causing the water product to freeze, (3) this phase transition buffers the sample temperatures within a narrow temperature range just below the ice point until dissociation goes to completion, and (4) the temperature depression below the pure ice melting point correlates with the average rate of dissociation and arises from solution of the hydrate-forming gas, released by dissociation, in the water phase at elevated concentrations. In addition, for hydrate that is partially dissociated to ice + gas at lower temperatures and then heated to temperatures above the ice point, all remaining hydrate dissociates to gas + liquid water as existing barriers to dissociation disappear. The enhanced dissociation rates at warmer temperatures are probably associated with faster gas transport pathways arising from the formation of water product.

  13. Retrievals of ethane from ground-based high-resolution FTIR solar observations with updated line parameters: determination of the optimum strategy for the Jungfraujoch station.

    NASA Astrophysics Data System (ADS)

    Bader, W.; Perrin, A.; Jacquemart, D.; Sudo, K.; Yashiro, H.; Gauss, M.; Demoulin, P.; Servais, C.; Mahieu, E.

    2012-04-01

    Ethane (C2H6) is the most abundant Non-Methane HydroCarbon (NMHC) in the Earth's atmosphere, with a lifetime of approximately 2 months. C2H6 has both anthropogenic and natural emission sources such as biomass burning, natural gas loss and biofuel consumption. Oxidation by the hydroxyl radical is by far the major C2H6 sink as the seasonally changing OH concentration controls the strong modulation of the ethane abundance throughout the year. Ethane lowers Cl atom concentrations in the lower stratosphere and is a major source of peroxyacetyl nitrate (PAN) and carbon monoxide (by reaction with OH). Involved in the formation of tropospheric ozone and in the destruction of atmospheric methane through changes in OH, C2H6 is a non-direct greenhouse gas with a net-global warming potential (100-yr horizon) of 5.5. The retrieval of ethane from ground-based infrared (IR) spectra is challenging. Indeed, the fitting of the ethane features is complicated by numerous interferences by strong water vapor, ozone and methane absorptions. Moreover, ethane has a complicated spectrum with many interacting vibrational modes and the current state of ethane parameters in HITRAN (e.g. : Rothman et al., 2009, see http://www.hitran.com) was rather unsatisfactory in the 3 μm region. In fact, PQ branches outside the 2973-3001 cm-1 range are not included in HITRAN, and most P and R structures are missing. New ethane absorption cross sections recorded at the Molecular Spectroscopy Facility of the Rutherford Appleton Laboratory (Harrison et al., 2010) are used in our retrievals. They were calibrated in intensity by using reference low-resolution spectra from the Pacific Northwest National Laboratory (PNNL) IR database. Pseudoline parameters fitted to these ethane spectra have been combined with HITRAN 2004 line parameters (including all the 2006 updates) for all other species encompassed in the selected microwindows. Also, the improvement brought by the update of the line positions and intensities of methyl chloride (CH3Cl) in the 3.4 μm region (Bray et al., 2011) will be quantified. The ethane a priori volume mixing ratio (VMR) profile and associated covariance are based on synthetic data from the chemical transport model (CTM) of the University of Oslo. In this contribution, we will present updated ethane total and tropospheric column retrievals, using the SFIT-2 algorithm (v3.91) and high-resolution Fourier Transform Infrared (FTIR) solar absorption observations recorded with a Bruker 120HR instrument, at the high altitude research station of the Jungfraujoch (46.5° N, 8° E, 3580 m asl), within the framework of the Network for the Detection of Atmospheric Composition Change (NDACC, visit http://www.ndacc.org). We will characterize three microwindows encompassing the strongest ethane features after careful selection of a priori VMR profiles, spectroscopic parameters, accounting at best for all interfering species. We will then present the retrieval strategy representative of the best combination of those three characterized micro-windows in order to minimize the fitting residuals while maximizing the information content, the precision and the reliability of the retrieved product. The long-term C2H6 column time series will be produced using the Jungfraujoch observational database. Comparisons with synthetic data produced by two chemical transport model (CHASER and the one of the University of Oslo) will also be presented and analyzed, aiming at the determination and interpretation of long-term trends and interannual variations of ethane at Northern mid-latitudes. Acknowledgments The University of Liège involvement has primarily been supported by the PRODEX program funded by the Belgian Federal Science Policy Office, Brussels and by the Swiss GAW-CH program. E. Mahieu is Research Associate with the F.R.S. - FNRS. The FRS-FNRS and the Fédération Wallonie-Bruxelles are further acknowledged for observational activities support. We thank the International Foundation High Altitude Research Stations Jungfraujoch and Gornergrat (HFSJG, Bern) for supporting the facilities needed to perform the observations. We further acknowledge the vital contribution from all the Belgian colleagues in performing the Jungfraujoch observations used here. We further thank G.C. Toon (NASA-JPL, Pasadena) for the conversion of the ethane cross sections into pseudolines which can be used by our retrieval algorithm.

  14. Mathematical modeling of the gas extraction from the gas hydrate deposit taking into account the replacement technology

    NASA Astrophysics Data System (ADS)

    Musakaev, N. G.; Khasanov, M. K.; Borodin, S. L.

    2018-03-01

    In the work on the basis of methods and equations of mechanics of multiphase systems the mathematical model of the process of carbon dioxide burial in the reservoir saturated with methane hydrate is proposed. Estimates are obtained that allow for this problem to neglect diffusion mixing of carbon dioxide and methane. The features of the process of methane displacement from CH4 hydrate by filling them with carbon dioxide are studied.

  15. Increased stray gas abundance in a subset of drinking water wells near Marcellus shale gas extraction

    PubMed Central

    Jackson, Robert B.; Vengosh, Avner; Darrah, Thomas H.; Warner, Nathaniel R.; Down, Adrian; Poreda, Robert J.; Osborn, Stephen G.; Zhao, Kaiguang; Karr, Jonathan D.

    2013-01-01

    Horizontal drilling and hydraulic fracturing are transforming energy production, but their potential environmental effects remain controversial. We analyzed 141 drinking water wells across the Appalachian Plateaus physiographic province of northeastern Pennsylvania, examining natural gas concentrations and isotopic signatures with proximity to shale gas wells. Methane was detected in 82% of drinking water samples, with average concentrations six times higher for homes <1 km from natural gas wells (P = 0.0006). Ethane was 23 times higher in homes <1 km from gas wells (P = 0.0013); propane was detected in 10 water wells, all within approximately 1 km distance (P = 0.01). Of three factors previously proposed to influence gas concentrations in shallow groundwater (distances to gas wells, valley bottoms, and the Appalachian Structural Front, a proxy for tectonic deformation), distance to gas wells was highly significant for methane concentrations (P = 0.007; multiple regression), whereas distances to valley bottoms and the Appalachian Structural Front were not significant (P = 0.27 and P = 0.11, respectively). Distance to gas wells was also the most significant factor for Pearson and Spearman correlation analyses (P < 0.01). For ethane concentrations, distance to gas wells was the only statistically significant factor (P < 0.005). Isotopic signatures (δ13C-CH4, δ13C-C2H6, and δ2H-CH4), hydrocarbon ratios (methane to ethane and propane), and the ratio of the noble gas 4He to CH4 in groundwater were characteristic of a thermally postmature Marcellus-like source in some cases. Overall, our data suggest that some homeowners living <1 km from gas wells have drinking water contaminated with stray gases. PMID:23798404

  16. Understanding decomposition and encapsulation energies of structure I and II clathrate hydrates

    NASA Astrophysics Data System (ADS)

    Alavi, Saman; Ohmura, Ryo

    2016-10-01

    When compressed with water or ice under high pressure and low temperature conditions, some gases form solid gas hydrate inclusion compounds which have higher melting points than ice under those pressures. In this work, we study the balance of the guest-water and water-water interaction energies that lead to the formation of the clathrate hydrate phases. In particular, molecular dynamics simulations with accurate water potentials are used to study the energetics of the formation of structure I (sI) and II (sII) clathrate hydrates of methane, ethane, and propane. The dissociation enthalpy of the clathrate hydrate phases, the encapsulation enthalpy of methane, ethane, and propane guests in the corresponding phases, and the average bonding enthalpy of water molecules are calculated and compared with accurate calorimetric measurements and previous classical and quantum mechanical calculations, when available. The encapsulation energies of methane, ethane, and propane guests stabilize the small and large sI and sII hydrate cages, with the larger molecules giving larger encapsulation energies. The average water-water interactions are weakened in the sI and sII phases compared to ice. The relative magnitudes of the van der Waals potential energy in ice and the hydrate phases are similar, but in the ice phase, the electrostatic interactions are stronger. The stabilizing guest-water "hydrophobic" interactions compensate for the weaker water-water interactions and stabilize the hydrate phases. A number of common assumptions regarding the guest-cage water interactions are used in the van der Waals-Platteeuw statistical mechanical theory to predict the clathrate hydrate phase stability under different pressure-temperature conditions. The present calculations show that some of these assumptions may not accurately reflect the physical nature of the interactions between guest molecules and the lattice waters.

  17. Understanding decomposition and encapsulation energies of structure I and II clathrate hydrates.

    PubMed

    Alavi, Saman; Ohmura, Ryo

    2016-10-21

    When compressed with water or ice under high pressure and low temperature conditions, some gases form solid gas hydrate inclusion compounds which have higher melting points than ice under those pressures. In this work, we study the balance of the guest-water and water-water interaction energies that lead to the formation of the clathrate hydrate phases. In particular, molecular dynamics simulations with accurate water potentials are used to study the energetics of the formation of structure I (sI) and II (sII) clathrate hydrates of methane, ethane, and propane. The dissociation enthalpy of the clathrate hydrate phases, the encapsulation enthalpy of methane, ethane, and propane guests in the corresponding phases, and the average bonding enthalpy of water molecules are calculated and compared with accurate calorimetric measurements and previous classical and quantum mechanical calculations, when available. The encapsulation energies of methane, ethane, and propane guests stabilize the small and large sI and sII hydrate cages, with the larger molecules giving larger encapsulation energies. The average water-water interactions are weakened in the sI and sII phases compared to ice. The relative magnitudes of the van der Waals potential energy in ice and the hydrate phases are similar, but in the ice phase, the electrostatic interactions are stronger. The stabilizing guest-water "hydrophobic" interactions compensate for the weaker water-water interactions and stabilize the hydrate phases. A number of common assumptions regarding the guest-cage water interactions are used in the van der Waals-Platteeuw statistical mechanical theory to predict the clathrate hydrate phase stability under different pressure-temperature conditions. The present calculations show that some of these assumptions may not accurately reflect the physical nature of the interactions between guest molecules and the lattice waters.

  18. Increased stray gas abundance in a subset of drinking water wells near Marcellus shale gas extraction.

    PubMed

    Jackson, Robert B; Vengosh, Avner; Darrah, Thomas H; Warner, Nathaniel R; Down, Adrian; Poreda, Robert J; Osborn, Stephen G; Zhao, Kaiguang; Karr, Jonathan D

    2013-07-09

    Horizontal drilling and hydraulic fracturing are transforming energy production, but their potential environmental effects remain controversial. We analyzed 141 drinking water wells across the Appalachian Plateaus physiographic province of northeastern Pennsylvania, examining natural gas concentrations and isotopic signatures with proximity to shale gas wells. Methane was detected in 82% of drinking water samples, with average concentrations six times higher for homes <1 km from natural gas wells (P = 0.0006). Ethane was 23 times higher in homes <1 km from gas wells (P = 0.0013); propane was detected in 10 water wells, all within approximately 1 km distance (P = 0.01). Of three factors previously proposed to influence gas concentrations in shallow groundwater (distances to gas wells, valley bottoms, and the Appalachian Structural Front, a proxy for tectonic deformation), distance to gas wells was highly significant for methane concentrations (P = 0.007; multiple regression), whereas distances to valley bottoms and the Appalachian Structural Front were not significant (P = 0.27 and P = 0.11, respectively). Distance to gas wells was also the most significant factor for Pearson and Spearman correlation analyses (P < 0.01). For ethane concentrations, distance to gas wells was the only statistically significant factor (P < 0.005). Isotopic signatures (δ(13)C-CH4, δ(13)C-C2H6, and δ(2)H-CH4), hydrocarbon ratios (methane to ethane and propane), and the ratio of the noble gas (4)He to CH4 in groundwater were characteristic of a thermally postmature Marcellus-like source in some cases. Overall, our data suggest that some homeowners living <1 km from gas wells have drinking water contaminated with stray gases.

  19. Simulation of ethane steam cracking with severity evaluation

    NASA Astrophysics Data System (ADS)

    Rosli, M. N.; Aziz, N.

    2016-11-01

    Understanding the influence of operating parameters towards cracking severity is paramount in ensuring optimum operation of an ethylene plant. However, changing the parameters in an actual plant for data collection can be dangerous. Thus, a simulation model for ethane steam cracking furnace is developed using ASPEN Plus for the assessment. The process performance is evaluated with cracking severity factors and main product yields. Three severity factors are used for evaluation due to their ease of measurement, which are methane yield (Ymet), Ethylene-Ethane Ratio (EER) and Propylene-Ethylene Ratio (PER). The result shows that cracking severity is primarily influenced by reactor temperature. Operating the furnace with coil outlet temperature ranging between 850°C to 950°C and steam-to-hydrocarbon ratio of 0.3 to 0.5 has led to optimum main product yield.

  20. Compound-Specific Stable Carbon Isotope Analysis of Low-Concentration Complex Hydrocarbon Mixtures from Natural Gas Hydrate Systems

    NASA Astrophysics Data System (ADS)

    Plummer, R. E.; Pohlman, J. W.; Coffin, R. B.

    2005-12-01

    A system has been developed to measure the stable carbon isotope (δ13C) composition of dissolved methane, ethane, and propane from natural sediment samples with headspace concentrations as low as 1 ppm using a modified Thermo Electron Trace gas chromatograph (GC) connected to a Finnigan Delta Plus XP isotope ratio mass spectrometer (IRMS). A cryofocusing inlet was connected to the GC which allows 0.02- to 15.0-ml injections into a 10-ml min-1 He carrier stream. Analytes from the variable-volume injection are focused into a small section of fused silica capillary, which is either empty or packed with Poraplot-Q, depending on the analyte(s) of interest. The analytes are then rapidly desorbed (100°C) onto the GC column (1.8 ml min-1), where they undergo separation, combustion and IRMS detection. The sensitivity of the IRMS was improved by the addition of high resistivity amplifiers so that measurements can be obtained with as little as 7-ng of carbon. The analytical precision (2σ) is less than 0.5‰ for methane analysis and less than 1‰ for ethane and propane analyses. The gases are standardized by tank CO2 which has been referenced to the NIST RM 8560 natural gas standard. The samples require no pretreatment, and can be analyzed rapidly (20 samples/day) and with minimal instrument training. Using this system, we have obtained complete stable carbon isotope ethane profiles from sediment cores from microbial and thermogenic gas hydrate regions on the Northern Cascadia Margin. We were able to differentiate the relative thermal and microbial contributions of the gases; and furthermore, we obtained clear evidence for ethanogenesis and ethane oxidation at depths similar to those where methanogenesis and anaerobic methane oxidation (AOM), respectively, occurred. This system will be utilized to analyze headspace and hydrate gas samples from IODP Leg 311. These data will allow us to fully characterize the thermogenic contributions and trace hydrocarbon biogeochemical cycling of hydrocarbons along the Expedition 311 margin-perpendicular transect.

  1. 33 CFR 127.005 - Definitions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... natural gas (LNG) means a liquid or semisolid consisting mostly of methane and small quantities of ethane...) WATERFRONT FACILITIES WATERFRONT FACILITIES HANDLING LIQUEFIED NATURAL GAS AND LIQUEFIED HAZARDOUS GAS General § 127.005 Definitions. As used in this part: Active means accomplishing the transfer of LHG or LNG...

  2. 33 CFR 127.005 - Definitions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... natural gas (LNG) means a liquid or semisolid consisting mostly of methane and small quantities of ethane...) WATERFRONT FACILITIES WATERFRONT FACILITIES HANDLING LIQUEFIED NATURAL GAS AND LIQUEFIED HAZARDOUS GAS General § 127.005 Definitions. As used in this part: Active means accomplishing the transfer of LHG or LNG...

  3. Desorption Kinetics of Ar, Kr, Xe, N2, O2, CO, Methane, Ethane, and Propane from Graphene and Amorphous Solid Water Surfaces

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

    Smith, R. Scott; May, Robert A.; Kay, Bruce D.

    2016-03-03

    The desorption kinetics for Ar, Kr, Xe, N2, O2, CO, methane, ethane, and propane from grapheme covered Pt(111) and amorphous solid water (ASW) surfaces are investigated using temperature programmed desorption (TPD). The TPD spectra for all of the adsorbates from graphene have well-resolved first, second, third, and multi- layer desorption peaks. The alignment of the leading edges is consistent the zero-order desorption for all of the adsorbates. An Arrhenius analysis is used to obtain desorption energies and prefactors for desorption from graphene for all of the adsorbates. In contrast, the leading desorption edges for the adsorbates from ASW do notmore » align (for coverages < 2 ML). The non-alignment of TPD leading edges suggests that there are multiple desorption binding sites on the ASW surface. Inversion analysis is used to obtain the coverage dependent desorption energies and prefactors for desorption from ASW for all of the adsorbates.« less

  4. Desorption Kinetics of Ar, Kr, Xe, N2, O2, CO, Methane, Ethane, and Propane from Graphene and Amorphous Solid Water Surfaces.

    PubMed

    Smith, R Scott; May, R Alan; Kay, Bruce D

    2016-03-03

    The desorption kinetics for Ar, Kr, Xe, N2, O2, CO, methane, ethane, and propane from graphene-covered Pt(111) and amorphous solid water (ASW) surfaces are investigated using temperature-programmed desorption (TPD). The TPD spectra for all of the adsorbates from graphene have well-resolved first, second, third, and multilayer desorption peaks. The alignment of the leading edges is consistent the zero-order desorption for all of the adsorbates. An Arrhenius analysis is used to obtain desorption energies and prefactors for desorption from graphene for all of the adsorbates. In contrast, the leading desorption edges for the adsorbates from ASW do not align (for coverages < 2 ML). The nonalignment of TPD leading edges suggests that there are multiple desorption binding sites on the ASW surface. Inversion analysis is used to obtain the coverage dependent desorption energies and prefactors for desorption from ASW for all of the adsorbates.

  5. Bis[1-meth­oxy-2,2,2-tris­(pyrazol-1-yl-κN 2)ethane]­nickel(II) bis­(tri­fluoro­methane­sulfonate) methanol disolvate

    PubMed Central

    Lyubartseva, Ganna; Parkin, Sean; Mallik, Uma Prasad

    2013-01-01

    In the title salt, [Ni(C12H14N6O)2](CF3SO3)2·2CH3OH, the NiII ion is coordinated by six N atoms from two tridentate 1-meth­oxy-2,2,2-tris­(pyrazol-1-yl)ethane ligands in a distorted octa­hedral geometry. The NiII ion is situated on an inversion centre. The Ni—N distances range from 2.0589 (19) to 2.0757 (19) Å, intra-ligand N—Ni—N angles range from 84.50 (8) to 85.15 (8)°, and adjacent inter-ligand N—Ni—N angles range between 94.85 (8) and 95.50 (8)°. In the crystal, O—H⋯O hydrogen bonds between methanol solvent mol­ecules and tri­fluoro­methane­sulfonate anions are observed. PMID:24098170

  6. Catalytic conversion of light alkanes, Phase 3. Topical report, January 1990--December 1992

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

    NONE

    The mission of this work is to devise a new catalyst which can be used in the first simple, economic process to convert the light alkanes in natural gas to an alcohol-rich oxygenated product which can either be used as an environmentally friendly, high-performance liquid fuel, or a precursor to a liquid hydrocarbon transportation fuel. The authors have entered the proof-of-concept stage for converting isobutane to tert butyl alcohol in a practical process and are preparing to enter proof-of-concept of a propane to isopropyl alcohol process in the near future. Methane and ethane are more refractory and thus more difficultmore » to oxidize than the C{sub 3} and C{sub 4} hydrocarbons. Nonetheless, advances made in this area indicate that further research progress could achieve the goal of their direct conversion to alcohols. Progress in Phase 3 catalytic vapor phase methane and ethane oxidation over metals in regular oxidic lattices are the subject of this topical report.« less

  7. Stability of methane in reduced C-O-H fluid at 6.3 GPa and 1300-1400°C

    NASA Astrophysics Data System (ADS)

    Sokol, A. G.; Tomilenko, A. A.; Bul'bak, T. A.; Palyanova, G. A.; Palyanov, Yu. N.; Sobolev, N. V.

    2017-06-01

    The composition of a reduced C-O-H fluid was studied by the method of chromatography-mass spectrometry under the conditions of 6.3 GPa, 1300-1400°C, and fO2 typical of the base of the subcratonic lithosphere. Fluids containing water (4.4-96.3 rel. %), methane (37.6-0.06 rel. %), and variable concentrations of ethane, propane, and butane were obtained in experiments. With increasing fO2, the proportion of the CH4/C2H6 peak areas on chromatograms first increases and then decreases, whereas the CH4/C3H8 and CH4/C4H10 ratios continually decrease. The new data show that ethane and heavier HCs may be more stable to oxidation, than previously thought. Therefore, when reduced fluids pass the "redox-front," carbon is not completely released from the fluid and may be involved in diamond formation.

  8. cis,cis,cis-(Acetato-κ(2) O,O')bis-[1,2-bis-(diphenyl-phosphan-yl)ethane-κ(2) P,P']ruthenium(II) 0.75-trifluoro-methane-sulfonate 0.25-chloride.

    PubMed

    Figueira, João; Rodrigues, João; Valkonen, Arto

    2013-04-01

    In the title Ru(II) carboxyl-ate compound, [Ru(C2H3O2)(C26H24P2)2](CF3O3S)0.75Cl0.25, the distorted tris-bidentate octa-hedral stereochemistry about the Ru(II) atom in the complex cation comprises four P-atom donors from two 1,2-bis-(diphenyl-phosphan-yl)ethane ligands [Ru-P = 2.2881 (13)-2.3791 (13) Å] and two O-atom donors from the acetate ligand [Ru-O = 2.191 (3) and 2.202 (3) Å]. The disordered counter-anions are located on the same site in the structure in a 3:1 ratio, the expanded formula comprising four complex cations, three trifluoro-methane-sulfonate anions and one chloride anion, with two such formula units in the unit cell.

  9. Analysis of methane biodegradation by Methylosinus trichosporium OB3b

    PubMed Central

    Rodrigues, Andréa dos Santos; Salgado, Belkis Valdman e Andréa Medeiros

    2009-01-01

    The microbial oxidation of methane in the atmosphere is performed by methanotrophic bacteria that use methane as a unique source of carbon and energy. The objective of this work consisted of the investigation of the best conditions of methane biodegradation by methanotrophic bacteria Methylosinus trichosporium OB3b that oxidize it to carbon dioxide, and the use of these microorganisms in monitoring methods for methane. The results showed that M. trichosporium OB3b was capable to degrade methane in a more effective way with an initial microorganism concentration of 0.0700 g.L-1, temperature of 30ºC, pH 6.5 and using 1.79 mmol of methane. In these same conditions, there was no bacterial growth when 2.69 mmol of methane was used. The specific rate of microorganism growth, the conversion factor, the efficiency and the volumetric productivity, for the optimized conditions of biodegradation were, respectively, 0.0324 h-1, 0.6830 gcells/gCH4, 73.73% and 2.7732.10-3 gcells/L.h. The final product of methane microbiological degradation, carbon dioxide, was quantified through the use of a commercial electrode, and, through this, the grade of methane conversion in carbon dioxide was calculated. PMID:24031362

  10. Turboexpander plant designs can provide high ethane recovery without inlet CO/sub 2/ removal

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

    Wilkinson, J.D.; Hudson, H.M.

    1982-05-03

    New turboexpander plant designs can process natural gas streams containing moderate amounts of carbon dioxide (CO/sub 2/) for high ethane recovery without inlet gas treating. The designs will handle a wide range of inlet ethane-plus fractions. They also offer reduced horsepower requirements compared to other processes. CO/sub 2/ is a typical component of most natural gas streams. In many cases, processing of these gas streams in a turboexpander plant for high ethane recovery requires pre-treatment of the gas for CO/sub 2/ removal. This is required to avoid the formation of solid CO/sub 2/ (freezing) in the cold sections of themore » process and/or to meet necessary residue gas and liquid product CO/sub 2/ specifications. Depending on the quantities involved, the CO/sub 2/ removal systems is generally a significant portion of both the installed cost and operating cost for the ethane recovery facility. Therefore, turboexpander plant designs that are capable of handling increased quantities of CO/sub 2/ in the feed gas without freezing can offer the gas processor substantial economic benefits.« less

  11. Correlation of refrigerant mass flow rate through adiabatic capillary tubes using mixture refrigerant carbondioxide and ethane for low temperature applications

    NASA Astrophysics Data System (ADS)

    Nasruddin, Syaka, Darwin R. B.; Alhamid, M. Idrus

    2012-06-01

    Various binary mixtures of carbon dioxide and hydrocarbons, especially propane or ethane, as alternative natural refrigerants to Chlorofluorocarbons (CFCs) or Hydro fluorocarbons (HFCs) are presented in this paper. Their environmental performance is friendly, with an ozone depletion potential (ODP) of zero and Global-warming potential (GWP) smaller than 20. The capillary tube performance for the alternative refrigerant HFC HCand mixed refrigerants have been widely studied. However, studies that discuss the performance of the capillary tube to a mixture of natural refrigerants, in particular a mixture of azeotrope carbon dioxide and ethane is still undeveloped. A method of empirical correlation to determine the mass flow rate and pipe length has an important role in the design of the capillary tube for industrial refrigeration. Based on the variables that effect the rate of mass flow of refrigerant in the capillary tube, the Buckingham Pi theorem formulated eight non-dimensional parameters to be developed into an empirical equations correlation. Furthermore, non-linear regression analysis used to determine the co-efficiency and exponent of this empirical correlation based on experimental verification of the results database.

  12. Kinetics of methane hydrate replacement with carbon dioxide and nitrogen gas mixture using in situ NMR spectroscopy.

    PubMed

    Cha, Minjun; Shin, Kyuchul; Lee, Huen; Moudrakovski, Igor L; Ripmeester, John A; Seo, Yutaek

    2015-02-03

    In this study, the kinetics of methane replacement with carbon dioxide and nitrogen gas in methane gas hydrate prepared in porous silica gel matrices has been studied by in situ (1)H and (13)C NMR spectroscopy. The replacement process was monitored by in situ (1)H NMR spectra, where about 42 mol % of the methane in the hydrate cages was replaced in 65 h. Large amounts of free water were not observed during the replacement process, indicating a spontaneous replacement reaction upon exposing methane hydrate to carbon dioxide and nitrogen gas mixture. From in situ (13)C NMR spectra, we confirmed that the replacement ratio was slightly higher in small cages, but due to the composition of structure I hydrate, the amount of methane evolved from the large cages was larger than that of the small cages. Compositional analysis of vapor and hydrate phases was also carried out after the replacement reaction ceased. Notably, the composition changes in hydrate phases after the replacement reaction would be affected by the difference in the chemical potential between the vapor phase and hydrate surface rather than a pore size effect. These results suggest that the replacement technique provides methane recovery as well as stabilization of the resulting carbon dioxide hydrate phase without melting.

  13. Co-crystal formation between two organic solids on the surface of Titan

    NASA Astrophysics Data System (ADS)

    Cable, M. L.; Vu, T. H.; Maynard-Casely, H. E.; Hodyss, R. P.

    2017-12-01

    Laboratory experiments of Titan molecular materials, informed by modeling, can help us to understand the complex and dynamic surface processes occurring on this moon at cryogenic temperatures. We previously demonstrated that two common organic materials on Titan, ethane and benzene, form a unique and stable co-crystalline structure at Titan surface temperatures. We have now characterized a second co-crystal that is stable on Titan, this time between two solids: acetylene and ammonia. The co-crystal forms within minutes at Titan surface temperature, as evidenced by new Raman spectral features in the lattice vibration and C-H bending regions. In addition, a red shift of the C-H stretching mode suggests that the acetylene-ammonia co-crystal is stabilized by a network of C-H···N interactions. Thermal stability studies indicate that this co-crystal remains intact to >110 K, and experiments with liquid methane and ethane reveal the co-crystal to be resistant to fluvial or pluvial exposure. Non-covalently bound structures such as these co-crystals point to far more complex surface interactions than previously believed on Titan. New physical and mechanical properties (deformation, plasticity, density, etc.), differences in storage of key species (i.e., ethane versus methane), variations in surface transport and new chemical gradients can all result in diverse surface features and chemistries of astrobiological interest.

  14. MODELING AROMATIC AND POLYCYCLIC AROMATIC HYDROCARBON FORMATION IN PREMIXED METHANE AND ETHANE FLAMES. (R825412)

    EPA Science Inventory

    The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Concl...

  15. 40 CFR 65.158 - Performance test procedures for control devices.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... loading period during which regulated materials are loaded, and samples shall be collected using... applicable. The regulated material concentration and percent reduction may be measured as either total regulated material or as TOC (minus methane and ethane) according to the procedures specified. (1) Method 1...

  16. 40 CFR 65.158 - Performance test procedures for control devices.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... loading period during which regulated materials are loaded, and samples shall be collected using... applicable. The regulated material concentration and percent reduction may be measured as either total regulated material or as TOC (minus methane and ethane) according to the procedures specified. (1) Method 1...

  17. 40 CFR 65.158 - Performance test procedures for control devices.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... loading period during which regulated materials are loaded, and samples shall be collected using... applicable. The regulated material concentration and percent reduction may be measured as either total regulated material or as TOC (minus methane and ethane) according to the procedures specified. (1) Method 1...

  18. 33 CFR 160.204 - Definitions.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... (ii) Ammonium nitrate based fertilizer listed as a Division 5.1 (oxidizing) material in 49 CFR 172.101... following: (1) Ammonium nitrate in bulk or ammonium nitrate based fertilizer in bulk remaining after all....7: (i) Ammonia, anhydrous; (ii) Chlorine; (iii) Ethane; (iv) Ethylene oxide; (v) Methane (LNG); (vi...

  19. 33 CFR 160.204 - Definitions.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... (ii) Ammonium nitrate based fertilizer listed as a Division 5.1 (oxidizing) material in 49 CFR 172.101... following: (1) Ammonium nitrate in bulk or ammonium nitrate based fertilizer in bulk remaining after all....7: (i) Ammonia, anhydrous; (ii) Chlorine; (iii) Ethane; (iv) Ethylene oxide; (v) Methane (LNG); (vi...

  20. 33 CFR 160.204 - Definitions.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (ii) Ammonium nitrate based fertilizer listed as a Division 5.1 (oxidizing) material in 49 CFR 172.101... following: (1) Ammonium nitrate in bulk or ammonium nitrate based fertilizer in bulk remaining after all....7: (i) Ammonia, anhydrous; (ii) Chlorine; (iii) Ethane; (iv) Ethylene oxide; (v) Methane (LNG); (vi...

  1. Influence of Oxygenated Compounds on Reaction Products in a Microwave Plasma Methane Pyrolysis Assembly for Post-Processing of Sabatier Methane

    NASA Technical Reports Server (NTRS)

    Mansell, J. Matthew; Abney, Morgan B.; Miller, Lee A.

    2011-01-01

    The state-of-the-art Carbon Dioxide Reduction Assembly (CRA) was delivered to the International Space Station (ISS) in April 2010. The system is designed to accept carbon dioxide from the Carbon Dioxide Removal Assembly and hydrogen from the Oxygen Generation Assembly. The two gases are reacted in the CRA in a Sabatier reactor to produce water and methane. Venting of methane results in an oxygen resupply requirement of about 378 lbs per crew member per year. If the oxygen is supplied as water, the total weight for resupply is about 476 lb per crew member per year. For long-term missions beyond low Earth orbit, during which resupply capabilities will be further limited, recovery of hydrogen from methane is highly desirable. For this purpose, NASA is pursuing development of a Plasma Pyrolysis Assembly (PPA) capable of recovering hydrogen from methane. Under certain conditions, water vapor and carbon dioxide (nominally intended to be separated from the CRA outlet stream) may be present in the PPA feed stream. Thus, testing was conducted in 2010 to determine the effect of these "oxygenated" compounds on PPA performance, particularly the effect of inlet carbon dioxide and water variations on the PPA product stream. This paper discusses the test set-up, analysis, and results of this testing

  2. Influence of Oxygenated Compounds on Reaction Products in a Microwave Plasma Methane Pyrolysis Assembly for Post-Processing of Sabatier Methane

    NASA Technical Reports Server (NTRS)

    Mansell, J. Matthew; Abney, Morgan B.

    2012-01-01

    The state-of-the-art Carbon Dioxide Reduction Assembly (CRA) was delivered to the International Space Station (ISS) in April 2010. The system is designed to accept carbon dioxide from the Carbon Dioxide Removal Assembly and hydrogen from the Oxygen Generation Assembly. The two gases are reacted in the CRA in a Sabatier reactor to produce water and methane. Venting of methane results in an oxygen resupply requirement of about 378 lbs per crew member per year. If the oxygen is supplied as water, the total weight for resupply is about 476 lb per crew member per year. For long-term missions beyond low Earth orbit, during which resupply capabilities will be further limited, recovery of hydrogen from methane is highly desirable. For this purpose, NASA is pursuing development of a Plasma Pyrolysis Assembly (PPA) capable of recovering hydrogen from methane. Under certain conditions, water vapor and carbon dioxide (nominally intended to be separated from the CRA outlet stream) may be present in the PPA feed stream. Thus, testing was conducted in 2010 to determine the effect of these oxygenated compounds on PPA performance, particularly the effect of inlet carbon dioxide and water variations on the PPA product stream. This paper discusses the test set-up, analysis, and results of this testing.

  3. Effects of fracture and crack healing in sI methane and sII methane-ethane gas hydrate

    NASA Astrophysics Data System (ADS)

    Helgerud, M. B.; Waite, W. F.; Stern, L. A.; Kirby, S. H.

    2005-12-01

    Cracking within gas hydrate-bearing sediment can occur in the field at core-scales, due to unloading as material is brought to the surface during conventional coring, and at reservoir scales if the formation is fractured prior to production. Cracking can weaken hydrate-bearing sediment, but can also provide additional surface area for dissociation and permeability pathways for enhanced gas and fluid flow. In pulse-transmission wave speed measurements, we observe cracking in laboratory-formed pure sI methane and sII methane-ethane hydrates when samples are axially unloaded while being held under gas pressure to maintain hydrate stability. Cracking events are inferred from repeated, sharp decreases in shear wave speed occurring concurrently with abrupt increases in sample length. We also visually observe cracks in the solid samples after their recovery from the apparatus following each experiment. Following a cracking event, we observe evidence of rapid crack healing, or annealing expressed as nearly complete recovery of the shear wave speed within approximately 20 minutes. Gas hydrate recrystallization, grain growth, and annealing have also been observed in optical cell experiments and SEM imagery over a similar time frame. In a recovered hydrate-bearing core that is repressurized for storage or experimentation, rapid crack healing and recrystallization can partly restore lost mechanical strength and raise wave speeds. In a fractured portion of a hydrate-bearing reservoir, the rapid healing process can close permeable cracks and reduce the surface area available for dissociation.

  4. Natural gas pipeline leaks across Washington, DC.

    PubMed

    Jackson, Robert B; Down, Adrian; Phillips, Nathan G; Ackley, Robert C; Cook, Charles W; Plata, Desiree L; Zhao, Kaiguang

    2014-01-01

    Pipeline safety in the United States has increased in recent decades, but incidents involving natural gas pipelines still cause an average of 17 fatalities and $133 M in property damage annually. Natural gas leaks are also the largest anthropogenic source of the greenhouse gas methane (CH4) in the U.S. To reduce pipeline leakage and increase consumer safety, we deployed a Picarro G2301 Cavity Ring-Down Spectrometer in a car, mapping 5893 natural gas leaks (2.5 to 88.6 ppm CH4) across 1500 road miles of Washington, DC. The δ(13)C-isotopic signatures of the methane (-38.2‰ ± 3.9‰ s.d.) and ethane (-36.5 ± 1.1 s.d.) and the CH4:C2H6 ratios (25.5 ± 8.9 s.d.) closely matched the pipeline gas (-39.0‰ and -36.2‰ for methane and ethane; 19.0 for CH4/C2H6). Emissions from four street leaks ranged from 9200 to 38,200 L CH4 day(-1) each, comparable to natural gas used by 1.7 to 7.0 homes, respectively. At 19 tested locations, 12 potentially explosive (Grade 1) methane concentrations of 50,000 to 500,000 ppm were detected in manholes. Financial incentives and targeted programs among companies, public utility commissions, and scientists to reduce leaks and replace old cast-iron pipes will improve consumer safety and air quality, save money, and lower greenhouse gas emissions.

  5. The development of novel simulation methodologies and intermolecular potential models for real fluids

    NASA Astrophysics Data System (ADS)

    Errington, Jeffrey Richard

    This work focuses on the development of intermolecular potential models for real fluids. United-atom models have been developed for both non-polar and polar fluids. The models have been optimized to the vapor-liquid coexistence properties. Histogram reweighting techniques were used to calculate phase behavior. The Hamiltonian scaling grand canonical Monte Carlo method was developed to enable the determination of thermodynamic properties of several related Hamiltonians from a single simulation. With this method, the phase behavior of variations of the Buckingham exponential-6 potential was determined. Reservoir grand canonical Monte Carlo simulations were developed to simulate molecules with complex architectures and/or stiff intramolecular constraints. The scheme is based on the creation of a reservoir of ideal chains from which structures are selected for insertion during a simulation. New intermolecular potential models have been developed for water, the n-alkane homologous series, benzene, cyclohexane, carbon dioxide, ammonia and methanol. The models utilize the Buckingham exponential-6 potential to model non-polar interactions and point charges to describe polar interactions. With the exception of water, the new models reproduce experimental saturated densities, vapor pressures and critical parameters to within a few percent. In the case of water, we found a set of parameters that describes the phase behavior better than other available point charge models while giving a reasonable description of the liquid structure. The mixture behavior of water-hydrocarbon mixtures has also been examined. The Henry's law constants of methane, ethane, benzene and cyclohexane in water were determined using Widom insertion and expanded ensemble techniques. In addition the high-pressure phase behavior of water-methane and water-ethane systems was studied using the Gibbs ensemble method. The results from this study indicate that it is possible to obtain a good description of the phase behavior of pure components using united-atom models. The mixture behavior of non-polar systems, including highly asymmetric components, was in good agreement with experiment. The calculations for the highly non-ideal water-hydrocarbon mixtures reproduced experimental behavior with varying degrees of success. The results indicate that multibody effects, such as polarizability, must be taken into account when modeling mixtures of polar and non-polar components.

  6. Airborne DOAS retrievals of methane, carbon dioxide, and water vapor concentrations at high spatial resolution: application to AVIRIS-NG

    NASA Astrophysics Data System (ADS)

    Thorpe, Andrew K.; Frankenberg, Christian; Thompson, David R.; Duren, Riley M.; Aubrey, Andrew D.; Bue, Brian D.; Green, Robert O.; Gerilowski, Konstantin; Krings, Thomas; Borchardt, Jakob; Kort, Eric A.; Sweeney, Colm; Conley, Stephen; Roberts, Dar A.; Dennison, Philip E.

    2017-10-01

    At local scales, emissions of methane and carbon dioxide are highly uncertain. Localized sources of both trace gases can create strong local gradients in its columnar abundance, which can be discerned using absorption spectroscopy at high spatial resolution. In a previous study, more than 250 methane plumes were observed in the San Juan Basin near Four Corners during April 2015 using the next-generation Airborne Visible/Infrared Imaging Spectrometer (AVIRIS-NG) and a linearized matched filter. For the first time, we apply the iterative maximum a posteriori differential optical absorption spectroscopy (IMAP-DOAS) method to AVIRIS-NG data and generate gas concentration maps for methane, carbon dioxide, and water vapor plumes. This demonstrates a comprehensive greenhouse gas monitoring capability that targets methane and carbon dioxide, the two dominant anthropogenic climate-forcing agents. Water vapor results indicate the ability of these retrievals to distinguish between methane and water vapor despite spectral interference in the shortwave infrared. We focus on selected cases from anthropogenic and natural sources, including emissions from mine ventilation shafts, a gas processing plant, tank, pipeline leak, and natural seep. In addition, carbon dioxide emissions were mapped from the flue-gas stacks of two coal-fired power plants and a water vapor plume was observed from the combined sources of cooling towers and cooling ponds. Observed plumes were consistent with known and suspected emission sources verified by the true color AVIRIS-NG scenes and higher-resolution Google Earth imagery. Real-time detection and geolocation of methane plumes by AVIRIS-NG provided unambiguous identification of individual emission source locations and communication to a ground team for rapid follow-up. This permitted verification of a number of methane emission sources using a thermal camera, including a tank and buried natural gas pipeline.

  7. LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Remote laser detection of natural gas leakages from pipelines

    NASA Astrophysics Data System (ADS)

    Petukhov, V. O.; Gorobets, V. A.; Andreev, Yu M.; Lanskii, G. V.

    2010-02-01

    A differential absorption lidar based on a tunable TEA CO2 laser emitting at 42 lines of the 'hot' 0111 — 1110 band in the range from 10.9 to 11.4 μm is developed for detecting natural gas leakages from oil pipelines by measuring the ethane content in the atmosphere. The ethane detection sensitivity is 0.9 ppm km. The presence of methane does not distort the measurement results. The developed lidar can detect the natural gas leakage from kilometre heights at the flying velocities up to 200 km h-1 and a probe pulse repetition rate of 5 Hz.

  8. Inhibition of Methanogenesis in Marine Sediments by Acetylene and Ethylene: Validity of the Acetylene Reduction Assay for Anaerobic Microcosms

    PubMed Central

    Oremland, Ronald S.; Taylor, Barrie F.

    1975-01-01

    Methanogenesis was irreversibly inhibited in sediments by concentrations of acetylene employed in nitrogen fixation assays (1 to 20%, vol/vol). Ethylene, but not ethane, also stopped methane production, and the inhibition was reversed by gassing with hydrogen. PMID:1190767

  9. Estimates of methane emissions from India using CH4-CO-C2H6 relationships from CARIBIC observations in monsoon convective outflow

    NASA Astrophysics Data System (ADS)

    Baker, A. K.; Rauthe-Schöch, A.; Schuck, T. J.; van Velthoven, P. F.; Slemr, F.; Brenninkmeijer, C. A.

    2010-12-01

    A large fraction of methane sources are anthropogenic, and include fossil fuel use, biomass/biofuel burning, agriculture and waste treatment. Recently, much attention regarding emissions of greenhouse gases has focused on large, developing nations, as their emissions are expected to rise rapidly over the coming decades. As the second most populous country in the world, and one of the fastest growing economies, India has been of particular interest. Arguably the most important feature of meteorology in India is the Asian summer monsoon. During the monsoon period there exists persistent deep convection over Southern Asia, and the composition of convected air masses is strongly influenced by emissions from India. This ultimately results in a well-mixed air parcel containing air from India being transported to the upper troposphere. Over the course of the 2008 monsoon period the CARIBIC (Civil Aircraft for the Regular Investigation of the atmosphere Based on an Instrument Container) passenger aircraft conducted monthly measurement flights which probed this outflow. Data collected during these flights provides a unique opportunity to examine sources of atmospheric species in India. Here we use measurements of methane (CH4), carbon monoxide (CO) and ethane (C2H6) from whole air samples collected during CARIBIC flights to estimate emissions of methane and to quantify those emissions related to flooding during the monsoon. Methane data from the monsoon period show enhancements inside the monsoon plume, which increase as the monsoon progresses. Using emission data for CO and ΔCH4/ΔCO derived from CARIBIC measurements, we estimate total methane emissions to be ~40 Tg yr-1. Relationships of methane to ethane, which shares the bulk of its sources with methane but lacks a biological component, are further used to estimate the fraction of “extra” emissions from biological activity related to increased monsoon rains. This additional methane is a considerable fraction of total methane emissions. As emissions from rice paddies, which are not restricted to the monsoon season, are estimated to be 4±2 Tg yr-1, we expect that the additional methane emitted during the monsoon season is a product of anaerobic microbial activity related to persistent and widespread flooding during the monsoon, although the exact sources cannot be identified from our data.

  10. Carbon Dioxide Methanation for Human Exploration of Mars: A Look at Catalyst Longevity and Activity Using Supported Ruthenium

    NASA Technical Reports Server (NTRS)

    Petersen, Elspeth M.; Meier, Anne J.; Tessonnier, Jean-Philippe

    2018-01-01

    Overarching Purpose: To design a carbon dioxide methanation/Sabatier reaction catalyst able to withstand variable conditions including fluctuations in bed temperature and feed flow rates for 480 days of remote operation to produce seven tons of methane. Current Study Purpose: Examine supported Ruthenium as a carbon dioxide methanation catalyst to determine the effects support properties have on the active phase by studying activity and selectivity. Objective: The remote operation of the Mars ISRU (In Situ Resources Utilization) lander to produce rocket fuel prior to crew arrival on the planet to power an ascent vehicle. Constraints: Long-term operation (480 days); Variable conditions: Feed gas flow rates, Feed gas flow ratios, Reactor bed temperature.

  11. Template-Assisted Wet-Combustion Synthesis of Fibrous Nickel-Based Catalyst for Carbon Dioxide Methanation and Methane Steam Reforming.

    PubMed

    Aghayan, M; Potemkin, D I; Rubio-Marcos, F; Uskov, S I; Snytnikov, P V; Hussainova, I

    2017-12-20

    Efficient capture and recycling of CO 2 enable not only prevention of global warming but also the supply of useful low-carbon fuels. The catalytic conversion of CO 2 into an organic compound is a promising recycling approach which opens new concepts and opportunities for catalytic and industrial development. Here we report about template-assisted wet-combustion synthesis of a one-dimensional nickel-based catalyst for carbon dioxide methanation and methane steam reforming. Because of a high temperature achieved in a short time during reaction and a large amount of evolved gases, the wet-combustion synthesis yields homogeneously precipitated nanoparticles of NiO with average particle size of 4 nm on alumina nanofibers covered with a NiAl 2 O 4 nanolayer. The as-synthesized core-shell structured fibers exhibit outstanding activity in steam reforming of methane and sufficient activity in carbon dioxide methanation with 100% selectivity toward methane formation. The as-synthesized catalyst shows stable operation under the reaction conditions for at least 50 h.

  12. Geochemical Tracers and Rates of Short-Chain Alkane Production in Gulf of Mexico Cold Seep Sediments

    NASA Astrophysics Data System (ADS)

    Sibert, R.; Bernard, B. B.; Brooks, J. M.; Hunter, K.; Joye, S. B.

    2014-12-01

    The organic-rich cold seep sediments in the deep Gulf of Mexico commonly contain mixtures of light hydrocarbon gases either dissolved in pore fluids, adsorbed to sediment particles, trapped in methane ice, or as free gas. The dominant component in these natural gas mixtures is typically methane (C1), but ethane (C2) and propane (C3) are nearly always present in trace or major amounts. The ratio of C1:C2:C3 varies but C2 and C3 are typically present at single digit percent levels, whereas methane usually dominates at >80%. Methane production proceeds by at least two well-studied mechanisms: either 1) by thermocatalytic cracking of fossil organic matter, or 2) as a direct product of microbial metabolism, methanogenesis. In contrast, ethane and propane production in deep-sea sediments has been historically attributed only to thermocatalytic processes. However, limited data suggests production of C2/C3 compounds through the activity of archaea. Such studies of microbial- driven dynamics of C2/C3 gases (i.e. 'alkanogenesis') in cold seep sediments are rare. Furthermore, the identities of potential substrates are poorly constrained and no attempt has been made to quantify production rates of C2/C3 gases. However, carbon isotopic data on ethane and propane from deep cores from the Gulf of Mexico suggest alkanogenesis at depth in the sediment column and alkane oxidation in uppermost oxidant-rich sediments. Here, we present the results of a series of incubation experiments using sediment slurries culled from GC600, one of the most prolific natural oil and gas seeps in the Gulf of Mexico. Rates of both alkane production and oxidation were measured under a variety of conditions to assess the net rates of alkane production and elucidate the driving microbiological mechanisms and controls on the central processes of >C1 alkane cycling in cold seep sediments. Microbial processes are important both in terms of alkane production and oxidation, raising many questions as to the biological production of these gases across the biosphere.

  13. Catalysts for conversion of methane to higher hydrocarbons

    DOEpatents

    Siriwardane, Ranjani V.

    1993-01-01

    Catalysts for converting methane to higher hydrocarbons such as ethane and ethylene in the presence of oxygen at temperatures in the range of about 700.degree. to 900.degree. C. are described. These catalysts comprise calcium oxide or gadolinium oxide respectively promoted with about 0.025-0.4 mole and about 0.1-0.7 mole sodium pyrophosphate. A preferred reaction temperature in a range of about 800.degree. to 850.degree. C. with a preferred oxygen-to-methane ratio of about 2:1 provides an essentially constant C.sub.2 hydrocarbon yield in the range of about 12 to 19 percent over a period of time greater than about 20 hours.

  14. 33 CFR 127.005 - Definitions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Chlorine T Dimethylamine F+T Ethane F Ethyl chloride F+T Ethylene F Ethylene oxide F+T Methyl-acetylene and propadiene (mixtures) F Methyl bromide F+T Methyl chloride F+T Propane F Propylene F Sulphur dioxide T Vinyl...

  15. 33 CFR 127.005 - Definitions.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Chlorine T Dimethylamine F+T Ethane F Ethyl chloride F+T Ethylene F Ethylene oxide F+T Methyl-acetylene and propadiene (mixtures) F Methyl bromide F+T Methyl chloride F+T Propane F Propylene F Sulphur dioxide T Vinyl...

  16. Formation and decomposition of ethane, propane, and carbon dioxide hydrates in silica gel mesopores under high pressure.

    PubMed

    Aladko, E Ya; Dyadin, Yu A; Fenelonov, V B; Larionov, E G; Manakov, A Yu; Mel'gunov, M S; Zhurko, F V

    2006-10-05

    The experimental data on decomposition temperatures for the gas hydrates of ethane, propane, and carbon dioxide dispersed in silica gel mesopores are reported. The studies were performed at pressures up to 1 GPa. It is shown that the experimental dependence of hydrate decomposition temperature on the size of pores that limit the size of hydrate particles can be described on the basis of the Gibbs-Thomson equation only if one takes into account changes in the shape coefficient that is present in the equation; in turn, the value of this coefficient depends on a method of mesopore size determination. A mechanism of hydrate formation in mesoporous medium is proposed. Experimental data providing evidence of the possibility of the formation of hydrate compounds in hydrophobic matrixes under high pressure are reported. Decomposition temperature of those hydrate compounds is higher than that for the bulk hydrates of the corresponding gases.

  17. Geochemical Monitoring Of The Gas Hydrate Production By CO2/CH4 Exchange In The Ignik Sikumi Gas Hydrate Production Test Well, Alaska North Slope

    NASA Astrophysics Data System (ADS)

    Lorenson, T. D.; Collett, T. S.; Ignik Sikumi, S.

    2012-12-01

    Hydrocarbon gases, nitrogen, carbon dioxide and water were collected from production streams at the Ignik Sikumi gas hydrate production test well (TD, 791.6 m), drilled on the Alaska North Slope. The well was drilled to test the feasibility of producing methane by carbon dioxide injection that replaces methane in the solid gas hydrate. The Ignik Sikumi well penetrated a stratigraphically-bounded prospect within the Eileen gas hydrate accumulation. Regionally, the Eileen gas hydrate accumulation overlies the more deeply buried Prudhoe Bay, Milne Point, and Kuparuk River oil fields and is restricted to the up-dip portion of a series of nearshore deltaic sandstone reservoirs in the Sagavanirktok Formation. Hydrate-bearing sandstones penetrated by Ignik Sikumi well occur in three primary horizons; an upper zone, ("E" sand, 579.7 - 597.4 m) containing 17.7 meters of gas hydrate-bearing sands, a middle zone ("D" sand, 628.2 - 648.6 m) with 20.4 m of gas hydrate-bearing sands and a lower zone ("C" sand, 678.8 - 710.8 m), containing 32 m of gas hydrate-bearing sands with neutron porosity log-interpreted average gas hydrate saturations of 58, 76 and 81% respectively. A known volume mixture of 77% nitrogen and 23% carbon dioxide was injected into an isolated section of the upper part of the "C" sand to start the test. Production flow-back part of the test occurred in three stages each followed by a period of shut-in: (1) unassisted flowback; (2) pumping above native methane gas hydrate stability conditions; and (3) pumping below the native methane gas hydrate stability conditions. Methane production occurred immediately after commencing unassisted flowback. Methane concentration increased from 0 to 40% while nitrogen and carbon dioxide concentrations decreased to 48 and 12% respectively. Pumping above the hydrate stability phase boundary produced gas with a methane concentration climbing above 80% while the carbon dioxide and nitrogen concentrations fell to 2 and 18% respectively. Pumping below the gas hydrate stability phase boundary occurred in two periods with the composition of the produced gases continually increasing in methane reaching an excess of 96%, along with carbon dioxide decreasing to <1% and nitrogen to ~3%. The isotopic composition of all the gases was monitored. Methane carbon and hydrogen isotopic compositions remained stable throughout the test, while the carbon dioxide carbon became isotopically heavier. Nitrogen isotopic composition remained stable or became slightly isotopically depleted at the later phase of the test. These results imply that the produced methane was not isotopically fractionated, whereas carbon dioxide was fractionated becoming isotopically heavier at the end of each production phase. In addition, water samples were analyzed during the production phase documenting an increase in salinity.

  18. Emissions From Miombo Woodland and Dambo Grassland Savanna Fires in Southern Africa

    NASA Astrophysics Data System (ADS)

    Sinha, P.; Hobbs, P. V.; Yokelson, R. J.; Blake, D. R.; Gao, S.; Kirchstetter, T. W.

    2003-12-01

    African savanna fires are the largest source of biomass burning emissions worldwide, and the miombo woodland ecosystem is the most abundant type of savanna in southern Africa. Dambo grasslands are major enclaves within miombo woodlands. Savanna fires in these two ecosystems accounted for over one-third of the total area burned in southern Africa during the dry season of 2000. Airborne measurements of trace gases and particles over and downwind of two prescribed savanna fires in plots of miombo woodland and dambo grassland were obtained on September 1 and September 5, 2000, respectively. These measurements provide emission factors for a number of gaseous species including carbon dioxide (CO2), carbon monoxide (CO), sulfur dioxide (SO2), dimethyl sulfide (DMS), nitrogen oxides (NOx), ammonia (NH3), hydrogen cyanide (HCN), methane (CH4), non-methane hydrocarbons (NMHC), halocarbons, oxygenated compounds, as well as for particulates. Emission factors for the two fires are combined with measurements of fuel loading, combustion completeness, and burned area to estimate the emissions of trace gases and particles from miombo woodland and dambo grassland fires in southern Africa during the dry season of 2000. These estimates indicate that in August and September of 2000 miombo woodland and dambo grassland fires in southern Africa accounted for about 30%, 25%, 15%, and 64% of the emissions of CO2, CO, total hydrocarbons, and total particulate matter, respectively, emitted from all types of savanna fires in southern Africa. It is also estimated that the ratios of dry season emissions from miombo woodland and dambo grassland fires in Zambia to annual emissions from the use of biofuels in Zambia for CO2, CO, NOx, formic acid, CH4, NH3, ethane, ethene, propene, acetylene, formaldehyde, methanol, and acetic acid are 3.2, 1.5, 7.2, 2.5, 0.2, 0.6, 0.2, 0.5, 0.4, 0.3, 0.6, 0.3, and 0.5, respectively.

  19. Results from the Gas Chromatograph Mass Spectrometer (GCMS) Experiment on the Cassini-Huygens Probe

    NASA Technical Reports Server (NTRS)

    Niemann, Hasso B.

    2006-01-01

    The GCMS was part of the instrument complement on the Cassini-Huygens Probe to measure in situ the chemical composition of the atmosphere during the probe descent and coupled with the Aerosol Collector Pyrolyser (ACP) experiment by serving as detector for the pyrolization products to determine the composition of the aerosol particles. The GCMS employed a quadrupole mass filter with a secondary electron multiplier detection system and a gas sampling system providing continuous direct atmospheric composition measurements and batch sampling through three gas chromatographic (GC) columns, a chemical scrubber and a hydrocarbon enrichment cell. The GCMS gas inlet was heated to prevent condensation, and to evaporate volatiles from the surface after impact. The GCMS collected data from an altitude of 146 km to ground impact. The Probe and the GCMS survived impact and collected data for 1 hour and 9 minutes on the surface. Mass spectra were collected during descent and on the ground over a range of m/z from 2 to 141. The major constituents of the lower atmosphere were confirmed to be NP and CH4. The methane mole fraction was uniform in the stratosphere. It increased below the tropopause, at about 32 km altitude, monotonically toward the surface, reaching a plateau at about 8 km at a level near saturation. After surface impact a steep increase of the methane signal was observed, suggesting evaporation of surface condensed methane due to heating by the GCMS sample inlet heater. The measured mole fraction of Ar-40 is 4.3 x 10(exp-5) and of Ar-36 is 2.8 x 10(exp -7). The other primordial noble gases were below mole fraction. The isotope ratios of C-12/C-13 determined from methane measurements are 82.3 and of N-14/N-15 determined from molecular nitrogen are 183. The D/H isotope ratio determined from the H2 and HD measurements is 2.3 x l0(exp -4). Carbon dioxide, ethane, acetylene and cyanogen were detected evaporating from the surface in addition to methane.

  20. Results from the Gas Chromatograph Mass Spectrometer (GCMS) Experiment on the Cassini-Huygens Probe

    NASA Technical Reports Server (NTRS)

    Niemann, Hasso; Atreya, S.; Demick-Monelara, J.; Haberman, J.; Harpold, D.; Kasprzak, W.; Owen, T.; Raaen, E.; Way, S.

    2006-01-01

    The Gas Chromatograph Mass Spectrometer was one of six instruments on the Cassini-Huygens Probe mission to Titan. The GCMS measured in situ the chemical composition of the atmosphere during the probe descent and served as the detector for the pyrolization products for the Aerosol Collector Pyrolyser (ACP) experiment to determine the composition of the aerosol particles. The GCMS collected data from an altitude of 146 km to ground impact. The Probe and the GCMS survived impact and collected data for 1 hour and 9 minutes on the surface. Mass spectra were collected during descent and on the ground over a range of mlz from 2 to 141. The major constituents of the lower atmosphere were confirmed to be N2 and CH4. The methane mole fraction was uniform in the stratosphere. It increased below the tropopause, at about 32 km altitude, monotonically toward the surface, reaching a plateau at about 8 km at a level near saturation. After surface impact a steep increase of the methane signal was observed, suggesting evaporation of surface condensed methane due to heating by the GCMS sample inlet heater. The measured mole fraction of Ar-40 is 4.3x10(exp -5) and of Ar-36 is 2.8x10(exp -7). The other primordial noble gases were below 10(exp -8) mole fraction. The isotope ratios of C-12/C-13 determined from methane measurements are 82.3 and of N-14/N-15 determined from molecular nitrogen are 183. The D/H isotope ratio determined from the H2 and HD measurements is 2.3x10(exp -4). Carbon dioxide, ethane, acetylene and cyanogen were detected evaporating from the surface in addition to methane. The GCMS employed a quadrupole mass filter with a secondary electron multiplier detection system and a gas sampling system providing continuous direct atmospheric composition measurements and batch sampling through three gas chromatographic (GC) columns, a chemical scrubber and a hydrocarbon enrichment cell. The GCMS gas inlet was heated to prevent condensation, and to evaporate volatiles from the surface after impact.

  1. The use of renewable energy in the form of methane via electrolytic hydrogen generation using carbon dioxide as the feedstock

    NASA Astrophysics Data System (ADS)

    Hashimoto, Koji; Kumagai, Naokazu; Izumiya, Koichi; Takano, Hiroyuki; Shinomiya, Hiroyuki; Sasaki, Yusuke; Yoshida, Tetsuya; Kato, Zenta

    2016-12-01

    The history reveals the continuous increase in world energy consumption and carbon emissions. For prevention of intolerable global warming and complete exhaustion of fossil fuels we need complete conversion from fossil fuel consumption to renewable energy. We have been performing the research and development of global carbon dioxide recycling for more than 25 years to supply renewable energy to the world in the form of methane produced by the reaction of carbon dioxide captured from chimney with hydrogen generated electrolytically using electricity generated by renewable energy. We created the cathode and anode for electrolytic hydrogen generation and the catalyst for carbon dioxide methanation by the reaction with hydrogen. The methane formation from renewable energy will be the most convenient and efficient key technology for the use of renewable energy by storage of intermittent and fluctuating electricity generated from renewable energy and by regeneration of stable electricity. Domestic and international cooperation of companies for industrialization is in progress.

  2. Novel Concept of Frequency-Combs Interferometric Spectroscopy in the Mid-IR for Significantly Enhanced Detection of Explosives

    DTIC Science & Technology

    2015-12-01

    frequency combs. Ultrasensitive detection of methane, isotopic carbon dioxide, carbon monoxide, formaldehyde, acetylene, and ethylene was performed in...rmaldehyde, acetylene, and ethylene was perfo rmed in the spectral range 2.5- 5 11111 using intracav ity spectroscopy in broadband optical parametric osc...trace point detection of methane, carbon dioxide, isotopic (13C02) carbon dioxide, carbon monoxide, ethylene , acetylene, and formaldehyde and

  3. 40 CFR 60.614 - Test methods and procedures.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... or TOC (less methane and ethane) reduction efficiency shall be prior to the inlet of the control... determining compliance with the 20 ppmv limit. The sampling site shall be the same as that of the TOC samples and the samples shall be taken during the same time that the TOC samples are taken. The TOC...

  4. 40 CFR 60.562-1 - Standards: Process emissions.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... methane and ethane) (TOC) by 98 weight percent, or to a concentration of 20 parts per million by volume (ppmv) on a dry basis, whichever is less stringent. The TOC is expressed as the sum of the actual... Polypropylene and Polyethylene Affected Facilities Procedure /a/ Applicable TOC weight percent range Control/no...

  5. Mutant strain of C. acetobutylicum and process for making butanol

    DOEpatents

    Jain, Mahendra K.; Beacom, Daniel; Datta, Rathin

    1993-01-01

    A biologically pure asporogenic mutant of Clostridium acetobutylicum is produced by growing sporogenic C. acetobutylicum ATCC 4259 and treating the parent strain with ethane methane sulfonate. The mutant which as been designated C. acetobutylicum ATCC 55025 is useful in an improved ABE fermentation process, and produces high concentrations of butanol and total solvents.

  6. Using biogenic sulfur gases as remotely detectable biosignatures on anoxic planets.

    PubMed

    Domagal-Goldman, Shawn D; Meadows, Victoria S; Claire, Mark W; Kasting, James F

    2011-06-01

    We used one-dimensional photochemical and radiative transfer models to study the potential of organic sulfur compounds (CS(2), OCS, CH(3)SH, CH(3)SCH(3), and CH(3)S(2)CH(3)) to act as remotely detectable biosignatures in anoxic exoplanetary atmospheres. Concentrations of organic sulfur gases were predicted for various biogenic sulfur fluxes into anoxic atmospheres and were found to increase with decreasing UV fluxes. Dimethyl sulfide (CH(3)SCH(3), or DMS) and dimethyl disulfide (CH(3)S(2)CH(3), or DMDS) concentrations could increase to remotely detectable levels, but only in cases of extremely low UV fluxes, which may occur in the habitable zone of an inactive M dwarf. The most detectable feature of organic sulfur gases is an indirect one that results from an increase in ethane (C(2)H(6)) over that which would be predicted based on the planet's methane (CH(4)) concentration. Thus, a characterization mission could detect these organic sulfur gases-and therefore the life that produces them-if it could sufficiently quantify the ethane and methane in the exoplanet's atmosphere.

  7. Cavity Ring Down and Thermal Lens Techniques Applied to Vibrational Spectroscopy of Gases and Liquids

    NASA Astrophysics Data System (ADS)

    Nyaupane, Parashu Ram

    Infrared (IR) and near-infrared (NIR) region gas temperature sensors have been used in the past because of its non-intrusive character and fast time response. In this dissertation cavity ring down (CRD) absorption of oxygen around the region 760 nm has been used to measure the temperature of flowing air in an open optical cavity. This sensor could be a convenient method for measuring the temperature at the input (cold air) and output (hot air) after cooling the blades of a gas turbine. The results could contribute to improvements in turbine blade cooling designs. Additionally, it could be helpful for high temperature measurement in harsh conditions like flames, boilers, and industrial pyrolysis ovens as well as remote sensing. We are interested in experiments that simulate the liquid methane and ethane lakes on Titan which is around the temperature of 94 K. Our specific goal is to quantify the solubility of unsaturated hydrocarbons in liquid ethane and methane. However, it is rather complicated to do so because of the low temperatures, low solubility and solvent effects. So, it is wise to do the experiments at higher temperature and test the suitability of the techniques. In these projects, we were trying to explore if our existing laboratory techniques were sensitive enough to obtain the solubility of unsaturated hydrocarbons in liquid ethane. First, we studied the thermal lens spectroscopy (TLS) of the (Deltav = 6) C-H overtone of benzene and naphthalene in hexane and CCl4 at room temperature.

  8. Phase and flow behavior of mixed gas hydrate systems during gas injection

    NASA Astrophysics Data System (ADS)

    Darnell, K.; Flemings, P. B.; DiCarlo, D. A.

    2017-12-01

    We present one-dimensional, multi-phase flow model results for injections of carbon dioxide and nitrogen mixtures, or flue gas, into methane hydrate bearing reservoirs. Our flow model is coupled to a thermodynamic simulator that predicts phase stabilities as a function of composition, so multiple phases can appear, disappear, or change composition as the injection invades the reservoir. We show that the coupling of multi-phase fluid flow with phase behavior causes preferential phase fractionation in which each component flows through the system at different speeds and in different phases. We further demonstrate that phase and flow behavior within the reservoir are driven by hydrate stability of each individual component in addition to the hydrate stability of the injection composition. For example, if carbon dioxide and nitrogen are both individually hydrate stable at the reservoir P-T conditions, then any injection composition will convert all available water into hydrate and plug the reservoir. In contrast, if only carbon dioxide is hydrate stable at the reservoir P-T conditions, then nitrogen preferentially stays in the gaseous phase, while the carbon dioxide partitions into the hydrate and liquid water phases. For all injections of this type, methane originally held in hydrate is released by dissociation into the nitrogen-rich gaseous phase. The net consequence is that a gas phase composed of nitrogen and methane propagates through the reservoir in a fast-moving front. A slower-moving front lags behind where carbon dioxide and nitrogen form a mixed hydrate, but methane is absent due to dissociation-induced methane stripping from the first, fast-moving front. The entire composition path traces through the phase space as the flow develops with each front moving at different, constant velocities. This behavior is qualitatively similar to the dynamics present in enhanced oil recovery or enhanced coalbed methane recovery. These results explain why the inclusion of nitrogen in mixed gas injection into methane hydrate reservoirs has been far more successful at producing methane than pure carbon dioxide injections. These results also provide a test for the validity of equilibrium thermodynamics in transport-dominated mixed hydrate systems that can be validated by laboratory-scale flow-through experiments.

  9. Quantifying alkane emissions in the Eagle Ford Shale using boundary layer enhancement

    NASA Astrophysics Data System (ADS)

    Roest, Geoffrey; Schade, Gunnar

    2017-09-01

    The Eagle Ford Shale in southern Texas is home to a booming unconventional oil and gas industry, the climate and air quality impacts of which remain poorly quantified due to uncertain emission estimates. We used the atmospheric enhancement of alkanes from Texas Commission on Environmental Quality volatile organic compound monitors across the shale, in combination with back trajectory and dispersion modeling, to quantify C2-C4 alkane emissions for a region in southern Texas, including the core of the Eagle Ford, for a set of 68 days from July 2013 to December 2015. Emissions were partitioned into raw natural gas and liquid storage tank sources using gas and headspace composition data, respectively, and observed enhancement ratios. We also estimate methane emissions based on typical ethane-to-methane ratios in gaseous emissions. The median emission rate from raw natural gas sources in the shale, calculated as a percentage of the total produced natural gas in the upwind region, was 0.7 % with an interquartile range (IQR) of 0.5-1.3 %, below the US Environmental Protection Agency's (EPA) current estimates. However, storage tanks contributed 17 % of methane emissions, 55 % of ethane, 82 % percent of propane, 90 % of n-butane, and 83 % of isobutane emissions. The inclusion of liquid storage tank emissions results in a median emission rate of 1.0 % (IQR of 0.7-1.6 %) relative to produced natural gas, overlapping the current EPA estimate of roughly 1.6 %. We conclude that emissions from liquid storage tanks are likely a major source for the observed non-methane hydrocarbon enhancements in the Northern Hemisphere.

  10. Gas geochemistry and methane emission from Dushanzi mud volcanoes in the southern Junggar Basin, NW China

    NASA Astrophysics Data System (ADS)

    Zheng, Guodong; Ma, Xiangxian; Guo, Zhengfu; Hilton, David R.; Xu, Wang; Liang, Shouyun; Fan, Qiaohui; Chen, Wenxing

    2017-11-01

    There are many mud volcanoes in the southern margin of the Junggar Basin, northwest China, of which the Dushanzi area is the most typical and active one, emitting large amount of greenhouse gases associated with water and mud. The emitted gas is dominated by methane (average 90.1%), together with other gases, such as ethane (4.84-5.46%), propane (0.06-0.90%), CO2 (0.67-1.0%), and N2 (2.8-3.3%). The carbon (δ13C1) and hydrogen (δD) isotopic ratios of methane are in the ranges of -40.6‰ to -45.0‰ and -221‰ to -249‰, respectively, whereas carbon isotope ratios of ethane (δ13C2) are -25.2‰ to -27.6‰. Based on δ13C values, the released gas is characterized as a thermogenic coal-type and possibly originated from the middle-low Jurassic coal-bearing sequences according to the gas-source correlation and regional geology. Helium isotopes show a crustal source. The methane flux of Dushanzi mud volcanoes from both macro-seepage (craters/vents) and micro-seepage (ground soil exhalation) ranged over the orders of magnitude, from 0.4-2.7 kg d-1 and 4950 mg m-2 d-1 on average, respectively. Positive CH4 fluxes from dry soil were widespread throughout the investigated areas. The total CH4 emission from Dushanzi mud volcanoes is estimated to be at least 22.6 tons a-1, of which about 89% is from micro-seepage surrounding the mud volcano vents.

  11. Assessment of potential for natural attenuation of chlorinated ethenes and ethanes in ground water at a petrochemical reclamation site, Harris County, Texas

    USGS Publications Warehouse

    Huff, Glenn F.; Braun, Christopher L.; Lee, Roger W.

    2000-01-01

    Redox conditions in the Numerous Sand Channels Zone beneath a petrochemical reclamation site in Harris County, Texas, range from sulfate reducing to methanogenic as indicated by the presence of methane in ground water and the range of molecular hydrogen concentrations. Assessment of the potential for reductive dechlorination using BIOCHLOR as a screening tool indicated conditions favoring anaerobic degradation of chlorinated organic compounds in the Numerous Sand Channels Zone. Evidence supporting reductive dechlorination includes apparently biogenic cis-1,2-dichloroethene; an increased ratio of 1,2-dichloroethane to 1,1,2-trichloroethane downgradient from the assumed contaminant source area; ethene and methane concentrations greater than background concentrations within the area of the contaminant plume; and a positive correlation of the ratio of ethene to vinyl chloride as a function of methane concentrations. The body of evidence presented in this report argues for hydrogenolysis of trichloroethene to cis-1,2-dichloroethene; of 1,1,2-trichloroethane to 1,2-dichloroethane; and of vinyl chloride to ethene within the Numerous Sand Channels Zone. Simulations using BIOCHLOR yielded apparent first-order decay constants for reductive dechlorination in the sequence Tetrachloroethene --> trichloroethene --> cis-1,2-dichloroethene --> vinyl chloride --> ethene within the range of literature values reported for each compound and apparent first-order decay constants for reductive dechlorination in the sequence 1,1,2-trichloroethane --> 1,2-dichloroethane slightly greater than literature values reported for each compound along the upgradient segment of a simulated ground-water flowpath. Except for vinyl chloride, apparent rates of reductive dechlorination for all simulated species show a marked decrease along the downgradient segment of the simulated ground-water flowpath. Evidence for reductive dechlorination of chlorinated ethenes within the Numerous Sand Channels Zone indicates potential for natural attenuation of chlorinated ethenes. Reductive dechlorination of chlorinated ethanes apparently occurs to a lesser extent, indicating relatively less potential for natural attenuation of chlorinated ethanes. Additional data are needed on the concentrations and distribution of chlorinated ethenes and ethanes in individual fine sand intervals of the Numerous Sand Channels Zone. This information, combined with lower minimum reporting levels for future chloroethane analyses, might enable a more complete and quantitative assessment of the potential for natural attenuation at the site.

  12. High-Resolution Spectroscopy of Stratospheric Ethane Following the Jupiter Impact of 2009

    NASA Technical Reports Server (NTRS)

    Fast, Kelly; Kostiuk, Theodor; Livengood, Timothy A.; Hewagama, Tilak; Amen, John

    2010-01-01

    We report on high-resolution infrared spectroscopy of ethane (C2H6) performed at the latitude of an impact site on Jupiter discovered on 19 July 2009 by A. Wesley from a location in Murrumbateman, Australia. The observations used the NASA Goddard Space Flight Center's Heterodyne Instrument for Planetary Wind and Composition (HIPWAC) at the NASA Infrared Telescope Facility (IRTF) on Mauna Kea, Hawaii. HIPWAC is a mid-infrared (9-12 microns) heterodyne spectrometer operating at the highest limit of spectral resolving power (lambda\\Delta\\lambda > l06), providing information on atmospheric constituent abundance and temperature through fully resolved tine shapes. Ethane is a stable trace product of methane photochemistry that is nearly uniformly mixed in Jupiter's stratosphere, providing an effective probe of that altitude region. Ethane emission line profiles near 11,74 microns in the Ug band were measured in Jupiter's stratosphere at 25 MHz (11.00083/cm) resolution. A sequence of spectra of ethane acquired over a range of longitude at the impact latitude (56S planetocentric) probes constituent abundance and temperature profile, both on and off the impact region. Near the site of the impact, ethane emission increased above levels measured well outside the impact region. Radiative transfer analysis indicates increased ethane mole fraction (30% greater). Variation in the measured continuum level and line intensities within 75deg of the impact longitude indicate the presence of an opacity source (haze) at altitudes near and above the tropopause and as high as the 10-mbar level near the impact site. The indication of possible haze opacity up to the 10-mbar level in the atmosphere is consistent with measurements made by HIPWAC's predecessor as part of the IRTF Shoemaker Levy-9 campaign in 1994.

  13. Reducing Open Cell Landfill Methane Emissions with a Bioactive Alternative Daily

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

    Helene Hilger; James Oliver; Jean Bogner

    2009-03-31

    Methane and carbon dioxide are formed in landfills as wastes degrade. Molecule-for-molecule, methane is about 20 times more potent than carbon dioxide at trapping heat in the earth's atmosphere, and thus, it is the methane emissions from landfills that are scrutinized. For example, if emissions composed of 60% methane and 40% carbon dioxide were changed to a mix that was 40% methane and 60% carbon dioxide, a 30% reduction in the landfill's global warming potential would result. A 10% methane, 90% carbon dioxide ratio will result in a 75% reduction in global warming potential compared to the baseline. Gas collectionmore » from a closed landfill can reduce emissions, and it is sometimes combined with a biocover, an engineered system where methane oxidizing bacteria living in a medium such as compost, convert landfill methane to carbon dioxide and water. Although methane oxidizing bacteria merely convert one greenhouse gas (methane) to another (carbon dioxide), this conversion can offer significant reductions in the overall greenhouse gas contribution, or global warming potential, associated with the landfill. What has not been addressed to date is the fact that methane can also escape from a landfill when the active cell is being filled with waste. Federal regulations require that newly deposited solid waste to be covered daily with a 6 in layer of soil or an alternative daily cover (ADC), such as a canvas tarp. The aim of this study was to assess the feasibility of immobilizing methane oxidizing bacteria into a tarp-like matrix that could be used for alternative daily cover at open landfill cells to prevent methane emissions. A unique method of isolating methanotrophs from landfill cover soil was used to create a liquid culture of mixed methanotrophs. A variety of prospective immobilization techniques were used to affix the bacteria in a tarp-like matrix. Both gel encapsulation of methanotrophs and gels with liquid cores containing methanotrophs were readily made but prone to rapid desiccation. Bacterial adsorption onto foam padding, natural sponge, and geotextile was successful. The most important factor for success appeared to be water holding capacity. Prototype biotarps made with geotextiles plus adsorbed methane oxidizing bacteria were tested for their responses to temperature, intermittent starvation, and washing (to simulate rainfall). The prototypes were mesophilic, and methane oxidation activity remained strong after one cycle of starvation but then declined with repeated cycles. Many of the cells detached with vigorous washing, but at least 30% appeared resistant to sloughing. While laboratory landfill simulations showed that four-layer composite biotarps made with two different types of geotextile could remove up to 50% of influent methane introduced at a flux rate of 22 g m{sup -2} d{sup -1}, field experiments did not yield high activity levels. Tests revealed that there were high hour-to-hour flux variations in the field, which, together with frequent rainfall events, confounded the field testing. Overall, the findings suggest that a methanotroph embedded biotarp appears to be a feasible strategy to mitigate methane emission from landfill cells, although the performance of field-tested biotarps was not robust here. Tarps will likely be best suited for spring and summer use, although the methane oxidizer population may be able to shift and adapt to lower temperatures. The starvation cycling of the tarp may require the capacity for intermittent reinoculation of the cells, although it is also possible that a subpopulation will adapt to the cycling and become dominant. Rainfall is not expected to be a major factor, because a baseline biofilm will be present to repopulate the tarp. If strong performance can be achieved and documented, the biotarp concept could be extended to include interception of other compounds beyond methane, such as volatile aromatic hydrocarbons and chlorinated solvents.« less

  14. Photoinduced ethane formation from reaction of ethene with matrix-isolated Ti, V, or Nb atoms.

    PubMed

    Thompson, Matthew G K; Parnis, J Mark

    2005-10-27

    The reactions of matrix-isolated Ti, V, or Nb atoms with ethene (C(2)H(4)) have been studied by FTIR absorption spectroscopy. Under conditions where the ethene dimer forms, metal atoms react with the ethene dimer to yield matrix-isolated ethane (C(2)H(6)) and methane. Under lower ethene concentration conditions ( approximately 1:70 ethene/Ar), hydridic intermediates of the types HMC(2)H(3) and H(2)MC(2)H(2) are also observed, and the relative yield of hydrocarbons is diminished. Reactions of these metals with perdeuterioethene, and equimolar mixtures of C(2)H(4) and C(2)D(4), yield products that are consistent with the production of ethane via a metal atom reaction involving at least two C(2)H(4) molecules. The absence of any other observed products suggests the mechanism also involves production of small, highly symmetric species such as molecular hydrogen and metal carbides. Evidence is presented suggesting that ethane production from the ethene dimer is a general photochemical process for the reaction of excited-state transition-metal atoms with ethene at high concentrations of ethene.

  15. Preliminary scattering kernels for ethane and triphenylmethane at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Cantargi, F.; Granada, J. R.; Damián, J. I. Márquez

    2017-09-01

    Two potential cold moderator materials were studied: ethane and triphenylmethane. The first one, ethane (C2H6), is an organic compound which is very interesting from the neutronic point of view, in some respects better than liquid methane to produce subthermal neutrons, not only because it remains in liquid phase through a wider temperature range (Tf = 90.4 K, Tb = 184.6 K), but also because of its high protonic density together with its frequency spectrum with a low rotational energy band. Another material, Triphenylmethane is an hydrocarbon with formula C19H16 which has already been proposed as a good candidate for a cold moderator. Following one of the main research topics of the Neutron Physics Department of Centro Atómico Bariloche, we present here two ways to estimate the frequency spectrum which is needed to feed the NJOY nuclear data processing system in order to generate the scattering law of each desired material. For ethane, computer simulations of molecular dynamics were done, while for triphenylmethane existing experimental and calculated data were used to produce a new scattering kernel. With these models, cross section libraries were generated, and applied to neutron spectra calculation.

  16. Low-Latitude Ethane Rain on Titan

    NASA Technical Reports Server (NTRS)

    Dalba, Paul A.; Buratti, Bonnie J.; Brown, R. H.; Barnes, J. W.; Baines, K. H.; Sotin, C.; Clark, R. N.; Lawrence, K. J.; Nicholson, P. D.

    2012-01-01

    Cassini ISS observed multiple widespread changes in surface brightness in Titan's equatorial regions over the past three years. These brightness variations are attributed to rainfall from cloud systems that appear to form seasonally. Determining the composition of this rainfall is an important step in understanding the "methanological" cycle on Titan. I use data from Cassini VIMS to complete a spectroscopic investigation of multiple rain-wetted areas. I compute "before-and-after" spectral ratios of any areas that show either deposition or evaporation of rain. By comparing these spectral ratios to a model of liquid ethane, I find that the rain is most likely composed of liquid ethane. The spectrum of liquid ethane contains multiple absorption features that fall within the 2-micron and 5-micron spectral windows in Titan's atmosphere. I show that these features are visible in the spectra taken of Titan's surface and that they are characteristically different than those in the spectrum of liquid methane. Furthermore, just as ISS saw the surface brightness reverting to its original state after a period of time, I show that VIMS observations of later flybys show the surface composition in different stages of returning to its initial form.

  17. The Cassini UVIS stellar probe of the Titan atmosphere.

    PubMed

    Shemansky, Donald E; Stewart, A Ian F; West, Robert A; Esposito, Larry W; Hallett, Janet T; Liu, Xianming

    2005-05-13

    The Cassini Ultraviolet Imaging Spectrometer (UVIS) observed the extinction of photons from two stars by the atmosphere of Titan during the Titan flyby. Six species were identified and measured: methane, acetylene, ethylene, ethane, diacetylene, and hydrogen cyanide. The observations cover altitudes from 450 to 1600 kilometers above the surface. A mesopause is inferred from extraction of the temperature structure of methane, located at 615 km with a temperature minimum of 114 kelvin. The asymptotic kinetic temperature at the top of the atmosphere determined from this experiment is 151 kelvin. The higher order hydrocarbons and hydrogen cyanide peak sharply in abundance and are undetectable below altitudes ranging from 750 to 600 km, leaving methane as the only identifiable carbonaceous molecule in this experiment below 600 km.

  18. Methane emission from flooded soils - from microorganisms to the atmosphere

    NASA Astrophysics Data System (ADS)

    Conrad, Ralf

    2016-04-01

    Methane is an important greenhouse gas that is affected by anthropogenic activity. The annual budget of atmospheric methane, which is about 600 million tons, is by more than 75% produced by methanogenic archaea. These archaea are the end-members of a microbial community that degrades organic matter under anaerobic conditions. Flooded rice fields constitute a major source (about 10%) of atmospheric methane. After flooding of soil, anaerobic processes are initiated, finally resulting in the disproportionation of organic matter to carbon dioxide and methane. This process occurs in the bulk soil, on decaying organic debris and in the rhizosphere. The produced methane is mostly ventilated through the plant vascular system into the atmosphere. This system also allows the diffusion of oxygen into the rizosphere, where part of the produced methane is oxidized by aerobic methanotrophic bacteria. More than 50% of the methane production is derived from plant photosynthetic products and is formed on the root surface. Methanocellales are an important group of methanogenic archaea colonizing rice roots. Soils lacking this group seem to result in reduced root colonization and methane production. In rice soil methane is produced by two major paths of methanogenesis, the hydrogenotrophic one reducing carbon dioxide to methane, and the aceticlastic one disproportionating acetate to methane and carbon dioxide. Theoretically, at least two third of the methane should be produced by aceticlastic and the rest by hydrogenotrophic methanogenesis. In nature, however, the exact contribution of the two paths can vary from zero to 100%. Several environmental factors, such as temperature and quality of organic matter affect the path of methane production. The impact of these factors on the composition and activity of the environmental methanogenic microbial community will be discussed.

  19. Spatial profiles of methane at the Swiss Plateau: A confrontation between measurements and emission inventories.

    NASA Astrophysics Data System (ADS)

    Bamberger, Ines; Eugster, Werner; Buchmann, Nina

    2013-04-01

    Methane and carbon dioxide are the two most prominent greenhouse gases in the atmosphere and a detailed knowledge about their sources is essential for climate predictions (Solomon et al., 2007). The knowledge about greenhouse gas fluxes is usually merged, albeit including considerable uncertainties, to emission inventories. To increase the quality of the inventories a comparison with measurements is necessary. We evaluate the values given by a Swiss emission inventory with regard to atmospheric measurements of methane in Switzerland. Spatial profiles of carbon dioxide and methane were investigated at the Swiss Plateau during two consecutive warm and sunny summer days in July 2012. For the mobile methane and carbon dioxide measurements a LGR methane analyser and a LI-COR closed-path infrared gas analyser (IRGA) were mounted on a car together with an AIRMAR WeatherStation to track geodetic-coordinates and meteorological parameters. First results of the measurements including aerial profiles of the greenhouse gases and bin-averaged elevation profiles of methane and temperature will be presented and a highly-resolved methane emission inventory will be evaluated in comparison with the spatial profiles of atmospheric methane at the Swiss Plateau. References: Solomon, S., Qin D., et al. (Eds.) (2007) Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, 996 S. pp., Cambridge University Press, Cambridge.

  20. Molecular simulation investigation into the performance of Cu-BTC metal-organic frameworks for carbon dioxide-methane separations.

    PubMed

    Gutiérrez-Sevillano, Juan José; Caro-Pérez, Alejandro; Dubbeldam, David; Calero, Sofía

    2011-12-07

    We report a molecular simulation study for Cu-BTC metal-organic frameworks as carbon dioxide-methane separation devices. For this study we have computed adsorption and diffusion of methane and carbon dioxide in the structure, both as pure components and mixtures over the full range of bulk gas compositions. From the single component isotherms, mixture adsorption is predicted using the ideal adsorbed solution theory. These predictions are in very good agreement with our computed mixture isotherms and with previously reported data. Adsorption and diffusion selectivities and preferential sitings are also discussed with the aim to provide new molecular level information for all studied systems.

  1. 40 CFR 63.772 - Test methods, compliance procedures, and compliance demonstrations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... conduct a performance test to determine percent emission reduction or outlet organic HAP or TOC... intervals in time, such as 15-minute intervals during the run. (B) The mass rate of either TOC (minus... either TOC (minus methane and ethane) or total HAP at the inlet of the control device (Ei) may be...

  2. 40 CFR 63.116 - Process vent provisions-performance test methods and procedures to determine compliance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... conduct a performance test to determine percent emission reduction or outlet organic HAP or TOC... organic HAP concentration and percent reduction may be measured as either total organic HAP or as TOC... measurement of total organic HAP or TOC (minus methane and ethane) concentrations in all vent streams and...

  3. 40 CFR 63.1282 - Test methods, compliance procedures, and compliance demonstrations.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... organic HAP or TOC concentration when a flare is used. (3) For a performance test conducted to demonstrate... intervals in time, such as 15-minute intervals during the run. (B) The mass rate of either TOC (minus... either TOC (minus methane and ethane) or total HAP at the inlet of the control device (Ei) may be...

  4. 40 CFR 63.1325 - Batch process vents-performance test methods and procedures to determine compliance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... either total organic HAP or TOC. For purposes of this paragraph (c), the term “batch emission episode... ensure the measurement of total organic HAP or TOC (minus methane and ethane) concentrations in all batch... organic HAP or TOC, as appropriate. Alternatively, any other method or data that has been validated...

  5. Investigating physical controls on methane and carbon dioxide fluxes over reservoirs using the eddy covariance method-abstract

    EPA Science Inventory

    Reservoirs are a globally important source of carbon to the atmosphere. Several recent studies have found that both carbon dioxide (CO2) and methane (CH4) emissions from reservoirs are currently being underestimated by up to 50%. This underestimation is due to inadequate characte...

  6. Investigating physical controls on methane and carbon dioxide fluxes over reservoirs using the eddy covariance method

    EPA Science Inventory

    Reservoirs are a globally important source of carbon to the atmosphere. Several recent studies have found that both carbon dioxide (CO2) and methane (CH4) emissions from reservoirs are currently being underestimated by up to 50%. This underestimation is due to inadequate characte...

  7. Microbial methane in the shallow Paleozoic sediments and glacial deposits of Illinois, U.S.A.

    USGS Publications Warehouse

    Coleman, D.D.; Liu, Chao-Li; Riley, K.M.

    1988-01-01

    Methane formed by the microbial decomposition of buried organic matter is virtually ubiquitous in the groundwaters of Illinois. Chemical and carbon isotopic compositions are reported for gas samples collected from over 200 private and municipal water wells and from 39 small gas wells completed in glacial deposits (drift-gas wells). Carbon and hydrogen isotopic data for methane, carbon dioxide and water show that these gases were formed by the carbon dioxide reduction pathway, the same mechanism which has been previously shown to be responsible for microbial methane formation in the marine environment. The isotopic composition of methane in these samples can be closely correlated with the chemical composition of the gas and with water chemistry. The data are interpreted as indicating that isotopically very light methane is found in waters where the residence time of groundwater in the methanogenesis zone was very short relative to the methane production rate. ?? 1988.

  8. Methane formation from the hydrogenation of carbon dioxide on Ni(110) surface--a density functional theoretical study.

    PubMed

    Bothra, Pallavi; Periyasamy, Ganga; Pati, Swapan K

    2013-04-21

    The complete hydrogenation mechanisms of CO2 are explored on Ni(110) surface catalyst using density functional theory. We have studied the possible hydrogenation mechanism to form product methane from the stable adsorption-co-adsorption intermediates of CO2 and H2 on Ni(110) surface. Our computations clearly elucidate that the mechanism for the formation of methyl, methoxy and methane moieties from carbon dioxide on the nickel catalyst. Moreover, our studies clearly show that the methane formation via hydroxyl carbonyl intermediate requires a lower energy barrier than via carbon monoxide and formate intermediates on the Ni(110) surface.

  9. A two-state computational investigation of methane C--H and ethane C--C oxidative addition to [CpM(PH3)]n+ (M = Co, Rh, Ir; n = 0, 1).

    PubMed

    Petit, Alban; Richard, Philippe; Cacelli, Ivo; Poli, Rinaldo

    2006-01-11

    Reductive elimination of methane from methyl hydride half-sandwich phosphane complexes of the Group 9 metals has been investigated by DFT calculations on the model system [CpM(PH(3))(CH(3))(H)] (M = Co, Rh, Ir). For each metal, the unsaturated product has a triplet ground state; thus, spin crossover occurs during the reaction. All relevant stationary points on the two potential energy surfaces (PES) and the minimum energy crossing point (MECP) were optimized. Spin crossover occurs very near the sigma-CH(4) complex local minimum for the Co system, whereas the heavier Rh and Ir systems remain in the singlet state until the CH(4) molecule is almost completely expelled from the metal coordination sphere. No local sigma-CH(4) minimum was found for the Ir system. The energetic profiles agree with the nonexistence of the Co(III) methyl hydride complex and with the greater thermal stability of the Ir complex relative to the Rh complex. Reductive elimination of methane from the related oxidized complexes [CpM(PH(3))(CH(3))(H)](+) (M = Rh, Ir) proceeds entirely on the spin doublet PES, because the 15-electron [CpM(PH(3))](+) products have a doublet ground state. This process is thermodynamically favored by about 25 kcal mol(-1) relative to the corresponding neutral system. It is essentially barrierless for the Rh system and has a relatively small barrier (ca. 7.5 kcal mol(-1)) for the Ir system. In both cases, the reaction involves a sigma-CH(4) intermediate. Reductive elimination of ethane from [CpM(PH(3))(CH(3))(2)](+) (M = Rh, Ir) shows a similar thermodynamic profile, but is kinetically quite different from methane elimination from [CpM(PH(3))(CH(3))(H)](+): the reductive elimination barrier is much greater and does not involve a sigma-complex intermediate. The large difference in the calculated activation barriers (ca. 12.0 and ca. 30.5 kcal mol(-1) for the Rh and Ir systems, respectively) agrees with the experimental observation, for related systems, of oxidatively induced ethane elimination when M = Rh, whereas the related Ir systems prefer to decompose by alternative pathways.

  10. Theoretical models for ice mixtures in outer solar system bodies

    NASA Astrophysics Data System (ADS)

    Escribano, R. M.; Gómez, P. C.; Molpeceres, G.; Timón, V.; Moreno, M. A.; Maté, B.

    2016-12-01

    In a recent work [1], we have measured the optical constants and band strengths of methane/ethane ice mixtures in the near- and mid-infrared ranges. We present here recent calculations on models for these and other ice mixtures containing water. Methane and ethane are constituents of planetary ices in our solar system. Methane has been detected in outer solar system bodies like Titan, Pluto, Charon, Triton, or other TNO's [2]. Ethane has also been identified in some of those objects [2]. The motivation of this work has been to provide new laboratory data and theoretical models that may contribute to the understanding of those systems, in the new era of TNO's knowledge opened up by the New Horizons mission [3,4]. The models are designed to cover a range of mixtures of molecular species that match the composition and density of some of the systems in outer solar systems bodies. The calculations include several steps: first, amorphous samples are generated, via a Metropolis Montecarlo procedure (see Figure, left); next, the amorphous structures are relaxed to reach a minimum in the potential energy surface; at this point, the harmonic vibrational spectrum is predicted. Finally, the relaxed structures are processed by ab initio molecular dynamics simulations with the final aim of obtaining an anharmonic prediction of the spectra, which includes the near-infrared region (see Figure, right). Both the harmonic and anharmonic spectra are compared to experimental measurements in the mid- and near-infrared regions. All calculations are carried out by means of Materials Studio software, using the Density Functional Theory method, with GGA-PBE functionals and Grimme D2 dispersion correction. Acknowledgements This research has been supported by the Spanish MINECO, Projects FIS2013-48087-C2-1-P. G.M. acknowledges MINECO PhD grant BES-2014-069355. We are grateful to V. J. Herrero and I. Tanarro for discussions. References [1] G. Molpeceres et al., Astrophys. J, accepted (2016). [2] D.P. Cruikshank et al., Icarus, 246, 82-92, 2015. [3] A. Stern et al., Science, 350, 260-292, 2015. [4] W.M. Grundy et al. Science, 351, 1283, 2016. Figure caption Left: Representation of an amorphous mixture with 1 methane and 3 water molecules; right: spectra predicted in the near-IR from a molecular dynamics calculation.

  11. Composition, seasonal change and bathymetry of Ligeia Mare, Titan, derived from its 2.2-cm thermal emission

    NASA Astrophysics Data System (ADS)

    Le Gall, A. A.; Malaska, M.; Lorenz, R. D.; Janssen, M. A.; Tokano, T.; Hayes, A.; Lunine, J. I.; Veyssière, G.; Mastrogiuseppe, M.; Karatekin, O.; Encrenaz, P.

    2015-12-01

    For the last 10 years, the Cassini RADAR has been exploring Saturn's moon Titan, the only planetary body besides Earth whose surface presently exhibits significant accumulations of liquids in the forms of lakes and seas. In particular, the passive Radiometer that is incorporated in this instrument has been recording the 2.2 cm-wavelength thermal emission from Titan's three seas. Radiometry observations provide new information beyond the active radar reflection data. In this paper, we analyze the radiometry observations collected from Feb. 2007 to July 2013 over one of these seas, Ligeia Mare, with the goal of providing constrains on its liquid composition, seafloor nature, bathymetry, and dynamics. In light of the two-layer model we have developed for this analysis, we find that the dielectric constant of the sea liquid is most likely smaller than 1.8, suggesting that the composition of Ligeia Mare is dominated by liquid methane rather than liquid ethane (although a ternary methane-ethane-nitrogen mixture cannot be ruled out). This result is further supported by the value we infer for the liquid loss tangent of 3-5×10-5. This value is in agreement with the one first published by Mastrogiuseppe et al. (2014) based on active radar observation. A high methane concentration suggests that Ligeia Mare is either a sea from which ethane has been removed by crustal interaction, or a sea primarely fed by methane-rich precipitation, or both. For the seafloor, a dielectric constant of 2.6-2.9±0.9 is determined. Though this result is not very constraining, we favor a scenario where the floor of Ligeia Mare is covered by a sludge of compacted and possibly nitrile-rich organic material formed by the deposition of photochemical haze or by rain-washing of the nearby shores. These results are then used to convert the radiometry mosaic of Ligeia Mare into a qualitative low-resolution bathymetry map. Lastly, we establish limits on the physical temperature variation of the sea between Feb. 2007 to July 2013, namely less than 2 K, providing a constraint on the relative amounts of solar heating and evaporative cooling currently being explored in ocean circulation models.

  12. Low-temperature superacid catalysis: Reactions of n - butane and propane catalyzed by iron- and manganese-promoted sulfated zirconia

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

    Tsz-Keung, Cheung; d`Itri, J.L.; Lange, F.C.

    1995-12-31

    The primary goal of this project is to evaluate the potential value of solid superacid catalysts of the sulfated zirconia type for light hydrocarbon conversion. The key experiments catalytic testing of the performance of such catalysts in a flow reactor fed with streams containing, for example, n-butane or propane. Fe- and Mn-promoted sulfated zirconia was used to catalyze the conversion of n-butane at atmospheric pressure, 225-450{degrees}C, and n-butane partial pressures in the range of 0.0025-0.01 atm. At temperatures <225{degrees}C, these reactions were accompanied by cracking; at temperatures >350{degrees}C, cracking and isomerization occurred. Catalyst deactivation, resulting at least in part frommore » coke formation, was rapid. The primary cracking products were methane, ethane, ethylene, and propylene. The observation of these products along with an ethane/ethylene molar ratio of nearly 1 at 450{degrees}C is consistent with cracking occurring, at least in part, by the Haag-Dessau mechanism, whereby the strongly acidic catalyst protonates n-butane to give carbonium ions. The rate of methane formation from n-butane cracking catalyzed by Fe- and Mn-promoted sulfated zirconia at 450{degrees}C was about 3 x 10{sup -8} mol/(g of catalyst {center_dot}s). The observation of butanes, pentanes, and methane as products is consistent with Olah superacid chemistry, whereby propane is first protonated by a very strong acid to form a carbonium ion. The carbonium ion then decomposes into methane and an ethyl cation which undergoes oligocondensation reactions with propane to form higher molecular weight alkanes. The results are consistent with the identification of iron- and manganese-promoted sulfated zirconia as a superacid.« less

  13. The long-term evolution of hydrocarbons in Jupiter's stratosphere

    NASA Astrophysics Data System (ADS)

    Melin, Henrik; Fletcher, Leigh N.; Greathouse, Thomas K.; Giles, Rohini Sara; Sinclair, James; Orton, Glenn S.; Irwin, Patrick Gerard Joseph

    2016-10-01

    We present the global distribution of hydrocarbons in Jupiter's stratosphere using ground-based mid-infrared R~15,000 TEXES observations from the NASA Infrared Telescope Facility (IRTF), obtained between 2013 and 2016. Ethane and acetylene are the primary products of methane photolysis in Jupiter's stratosphere, and their spatial distribution can be used to trace atmospheric circulation and the lifetimes of chemical constituents. Zonal mean distributions of these species have been previously studied from the Voyager and Cassini spacecraft (Nixon et al., 2010, doi: 10.1016/j.pss.2010.05.008), but the TEXES dataset now provides the opportunity to track the evolution of the hydrocarbons from Earth (Fletcher et al., 2016, doi:10.1016/j.icarus.2016.06.008 ). Global spectral maps of methane, ethane and acetylene emission are used to characterize the temporal evolution of large scale features in Jupiter's stratosphere (0.5-20 mbar?), including: equator to pole contrasts driven by large-scale stratospheric overturning; mid-latitude bands of elevated hydrocarbon emission; small-scale wave phenomena driven by meteorological activity in the underlying troposphere; and the tropical changes in emission related to Jupiter's Quasi-Quadrennial Oscillation. The NEMESIS spectral inversion tool (Irwin et al., 2008, doi: 10.1016/j.jqsrt.2007.11.006) is used to derive stratospheric temperatures and hydrocarbon abundances from spatially-resolved spectra at 744, 819, and 1247 cm-1. We use these to investigate the changes in the vertical temperature and ethane and acetylene distributions over time, with the aim of providing the global and temporal context for Juno's exploration of the jovian atmosphere in 2016/17.

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

    Valysaev, B.M.; Erokhin, V.E.; Grinchenko, Y.I.

    A study has been made of the isotopic composition of the carbon in methane and carbon dioxide, as well as hydrogen in the methane, in the gases of mud volcanoes, for all main mud volcano areas in the USSR. The isotopic composition of carbon and hydrogen in methane shows that the gases resemble those of oil and gas deposits, while carbon dioxide of these volcanoes has a heavier isotopic composition with a greater presence of ''ultraheavy'' carbon dioxide. By the chemical and isotopic composition of gases, Azerbaidzhan and South Sakhalin types of mud volcano gases have been identified, as wellmore » as Bulganak subtypes and Akhtala and Kobystan varieties. Correlations are seen between the isotopic composition of gases and the geological build of mud volcano areas.« less

  15. Temperature-pressure conditions in coalbed methane reservoirs of the Black Warrior basin: Implications for carbon sequestration and enhanced coalbed methane recovery

    USGS Publications Warehouse

    Pashin, J.C.; McIntyre, M.R.

    2003-01-01

    Sorption of gas onto coal is sensitive to pressure and temperature, and carbon dioxide can be a potentially volatile supercritical fluid in coalbed methane reservoirs. More than 5000 wells have been drilled in the coalbed methane fields of the Black Warrior basin in west-central Alabama, and the hydrologic and geothermic information from geophysical well logs provides a robust database that can be used to assess the potential for carbon sequestration in coal-bearing strata.Reservoir temperature within the coalbed methane target zone generally ranges from 80 to 125 ??F (27-52 ??C), and geothermal gradient ranges from 6.0 to 19.9 ??F/1000 ft (10.9-36.2 ??C/km). Geothermal gradient data have a strong central tendency about a mean of 9.0 ??F/1000 ft (16.4 ??C/km). Hydrostatic pressure gradients in the coalbed methane fields range from normal (0.43 psi/ft) to extremely underpressured (<0.05 psi/ft). Pressure-depth plots establish a bimodal regime in which 70% of the wells have pressure gradients greater than 0.30 psi/ft, and 20% have pressure gradients lower than 0.10 psi/ft. Pockets of underpressure are developed around deep longwall coal mines and in areas distal to the main hydrologic recharge zone, which is developed in structurally upturned strata along the southeastern margin of the basin.Geothermal gradients within the coalbed methane fields are high enough that reservoirs never cross the gas-liquid condensation line for carbon dioxide. However, reservoirs have potential for supercritical fluid conditions beyond a depth of 2480 ft (756 m) under normally pressured conditions. All target coal beds are subcritically pressured in the northeastern half of the coalbed methane exploration fairway, whereas those same beds were in the supercritical phase window prior to gas production in the southwestern half of the fairway. Although mature reservoirs are dewatered and thus are in the carbon dioxide gas window, supercritical conditions may develop as reservoirs equilibrate toward a normal hydrostatic pressure gradient after abandonment. Coal can hold large quantities of carbon dioxide under supercritical conditions, and supercritical isotherms indicate non-Langmiur conditions under which some carbon dioxide may remain mobile in coal or may react with formation fluids or minerals. Hence, carbon sequestration and enhanced coalbed methane recovery show great promise in subcritical reservoirs, and additional research is required to assess the behavior of carbon dioxide in coal under supercritical conditions where additional sequestration capacity may exist. ?? 2003 Elsevier Science B.V. All rights reserved.

  16. Biocatalytic methanation of hydrogen and carbon dioxide in an anaerobic three-phase system.

    PubMed

    Burkhardt, M; Koschack, T; Busch, G

    2015-02-01

    A new type of anaerobic trickle-bed reactor was used for biocatalytic methanation of hydrogen and carbon dioxide under mesophilic temperatures and ambient pressure in a continuous process. The conversion of gaseous substrates through immobilized hydrogenotrophic methanogenic archaea in a biofilm is a unique feature of this type of reactor. Due to the formation of a three-phase system on the carrier surface and operation as a plug flow reactor without gas recirculation, a complete reaction could be observed. With a methane concentration higher than c(CH4) = 98%, the product gas exhibits a very high quality. A specific methane production of P(CH4) = 1.49 Nm(3)/(m(3)(SV) d) was achieved at a hydraulic loading rate of LR(H2) = 6.0 Nm(3)/(m(3)(SV) d). The relation between trickle flow through the reactor and productivity could be shown. An application for methane enrichment in combination with biogas facilities as a source of carbon dioxide has also been positively proven. Copyright © 2014 Elsevier Ltd. All rights reserved.

  17. Methane production by attached film

    DOEpatents

    Jewell, William J.

    1981-01-01

    A method for purifying wastewater of biodegradable organics by converting the organics to methane and carbon dioxide gases is disclosed, characterized by the use of an anaerobic attached film expanded bed reactor for the reaction process. Dilute organic waste material is initially seeded with a heterogeneous anaerobic bacteria population including a methane-producing bacteria. The seeded organic waste material is introduced into the bottom of the expanded bed reactor which includes a particulate support media coated with a polysaccharide film. A low-velocity upward flow of the organic waste material is established through the bed during which the attached bacterial film reacts with the organic material to produce methane and carbon dioxide gases, purified water, and a small amount of residual effluent material. The residual effluent material is filtered by the film as it flows upwardly through the reactor bed. In a preferred embodiment, partially treated effluent material is recycled from the top of the bed to the bottom of the bed for further treatment. The methane and carbon dioxide gases are then separated from the residual effluent material and purified water.

  18. 40 CFR 63.115 - Process vent provisions-methods and procedures for process vent group determination.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 2 process vent definition of this subpart shall measure either total organic HAP or TOC... either TOC (minus methane and ethane) or organic HAP shall be calculated according to paragraph (c)(3)(ii)(A) or (c)(3)(ii)(B) of this section as applicable. (A) The TOC concentration (CTOC) is the sum of...

  19. 40 CFR 63.490 - Batch front-end process vents-performance test methods and procedures to determine compliance.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... may be based on either total organic HAP or TOC. For purposes of this paragraph (c), the term “batch... inlet sampling sites shall ensure the measurement of total organic HAP or TOC (minus methane and ethane... used to determine the concentration of organic HAP or TOC, as appropriate. Alternatively, any other...

  20. 40 CFR 63.2535 - What compliance options do I have if part of my plant is subject to both this subpart and another...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Standards for Hazardous Air Pollutants: Miscellaneous Organic Chemical Manufacturing Other Requirements and...., organic chemicals subject to § 63.2435(b)(1), pharmaceutical products subject to § 63.1250, or pesticide... compliance, you must consider all total organic compounds, minus methane and ethane, in such equipment for...

  1. 40 CFR 63.2535 - What compliance options do I have if part of my plant is subject to both this subpart and another...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... Hazardous Air Pollutants: Miscellaneous Organic Chemical Manufacturing Other Requirements and Information...., organic chemicals subject to § 63.2435(b)(1), pharmaceutical products subject to § 63.1250, or pesticide... compliance, you must consider all total organic compounds, minus methane and ethane, in such equipment for...

  2. 40 CFR 63.2535 - What compliance options do I have if part of my plant is subject to both this subpart and another...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Hazardous Air Pollutants: Miscellaneous Organic Chemical Manufacturing Other Requirements and Information...., organic chemicals subject to § 63.2435(b)(1), pharmaceutical products subject to § 63.1250, or pesticide... compliance, you must consider all total organic compounds, minus methane and ethane, in such equipment for...

  3. 40 CFR 60.4241 - What are my compliance requirements if I am a manufacturer of stationary SI internal combustion...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... meets the definition of pipeline-quality natural gas. The fuel used for certifying stationary SI natural... a gas chromatograph as allowed under 40 CFR 1065.267 and may measure ethane, as well as methane, for... stationary SI engines as certified or non-certified engines. (d) Manufacturers of natural gas fired...

  4. 40 CFR 60.4241 - What are my compliance requirements if I am a manufacturer of stationary SI internal combustion...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... meets the definition of pipeline-quality natural gas. The fuel used for certifying stationary SI natural... a gas chromatograph as allowed under 40 CFR 1065.267 and may measure ethane, as well as methane, for... stationary SI engines as certified or non-certified engines. (d) Manufacturers of natural gas fired...

  5. 40 CFR Figure 1 to Subpart G of... - Definitions of Terms Used in Wastewater Equations

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... Wastewater Equations 1 Figure 1 to Subpart G of Part 63 Protection of Environment ENVIRONMENTAL PROTECTION... Wastewater Pt. 63, Subpt. G, Fig. 1 Figure 1 to Subpart G of Part 63—Definitions of Terms Used in Wastewater... wastewater, ppmw. CG=Concentration of TOC (minus methane and ethane) or total organic hazardous air...

  6. 40 CFR Figure 1 to Subpart G of... - Definitions of Terms Used in Wastewater Equations

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... Wastewater Equations 1 Figure 1 to Subpart G of Part 63 Protection of Environment ENVIRONMENTAL PROTECTION... Wastewater Pt. 63, Subpt. G, Fig. 1 Figure 1 to Subpart G of Part 63—Definitions of Terms Used in Wastewater... wastewater, ppmw. CG=Concentration of TOC (minus methane and ethane) or total organic hazardous air...

  7. 40 CFR Figure 1 to Subpart G of... - Definitions of Terms Used in Wastewater Equations

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... Wastewater Equations 1 Figure 1 to Subpart G of Part 63 Protection of Environment ENVIRONMENTAL PROTECTION... Wastewater Pt. 63, Subpt. G, Fig. 1 Figure 1 to Subpart G of Part 63—Definitions of Terms Used in Wastewater... wastewater, ppmw. CG=Concentration of TOC (minus methane and ethane) or total organic hazardous air...

  8. Bis[1-meth­oxy-2,2,2-tris­(pyrazol-1-yl-κN 2)ethane]­nickel(II) bis­(tri­fluoro­methane­sulfonate) dihydrate

    PubMed Central

    Lyubartseva, Ganna; Parkin, Sean; Mallik, Uma Prasad

    2013-01-01

    In the title salt, [Ni(C12H14N6O)2](CF3SO3)2·2H2O, the NiII cation is located on an inversion centre and is coordinated by six N atoms from two tridentate 1-meth­oxy-2,2,2-tris­(pyrazol-1-yl)ethane ligands in a distorted octa­hedral geometry. The Ni—N distances range from 2.0594 (12) to 2.0664 (12) Å, intra-ligand N—Ni—N angles range from 84.59 (5) to 86.06 (5)°, and adjacent inter-ligand N—Ni—N angles range between 93.94 (5) and 95.41 (5)°. In the crystal, inversion-related pyrazole rings are π–π stacked, with an inter­planar spacing of 3.4494 (18) Å, forming chains that propagate parallel to the a-axis direction. Inter­molecular O—H⋯O hydrogen bonds are present between water mol­ecules and tri­fluoro­methane­sulfonate anions. PMID:24098167

  9. Using Biogenic Sulfur Gases as Remotely Detectable Biosignatures on Anoxic Planets

    PubMed Central

    Meadows, Victoria S.; Claire, Mark W.; Kasting, James F.

    2011-01-01

    Abstract We used one-dimensional photochemical and radiative transfer models to study the potential of organic sulfur compounds (CS2, OCS, CH3SH, CH3SCH3, and CH3S2CH3) to act as remotely detectable biosignatures in anoxic exoplanetary atmospheres. Concentrations of organic sulfur gases were predicted for various biogenic sulfur fluxes into anoxic atmospheres and were found to increase with decreasing UV fluxes. Dimethyl sulfide (CH3SCH3, or DMS) and dimethyl disulfide (CH3S2CH3, or DMDS) concentrations could increase to remotely detectable levels, but only in cases of extremely low UV fluxes, which may occur in the habitable zone of an inactive M dwarf. The most detectable feature of organic sulfur gases is an indirect one that results from an increase in ethane (C2H6) over that which would be predicted based on the planet's methane (CH4) concentration. Thus, a characterization mission could detect these organic sulfur gases—and therefore the life that produces them—if it could sufficiently quantify the ethane and methane in the exoplanet's atmosphere. Key Words: Exoplanets—Biosignatures—Anoxic atmospheres—Planetary atmospheres—Remote life detection—Photochemistry. Astrobiology 11, 419–441. PMID:21663401

  10. Atmospheric methane isotopic record favors fossil sources flat in 1980s and 1990s with recent increase.

    PubMed

    Rice, Andrew L; Butenhoff, Christopher L; Teama, Doaa G; Röger, Florian H; Khalil, M Aslam K; Rasmussen, Reinhold A

    2016-09-27

    Observations of atmospheric methane (CH4) since the late 1970s and measurements of CH4 trapped in ice and snow reveal a meteoric rise in concentration during much of the twentieth century. Since 1750, levels of atmospheric CH4 have more than doubled to current globally averaged concentration near 1,800 ppb. During the late 1980s and 1990s, the CH4 growth rate slowed substantially and was near or at zero between 1999 and 2006. There is no scientific consensus on the drivers of this slowdown. Here, we report measurements of the stable isotopic composition of atmospheric CH4 ((13)C/(12)C and D/H) from a rare air archive dating from 1977 to 1998. Together with more modern records of isotopic atmospheric CH4, we performed a time-dependent retrieval of methane fluxes spanning 25 y (1984-2009) using a 3D chemical transport model. This inversion results in a 24 [18, 27] Tg y(-1) CH4 increase in fugitive fossil fuel emissions since 1984 with most of this growth occurring after year 2000. This result is consistent with some bottom-up emissions inventories but not with recent estimates based on atmospheric ethane. In fact, when forced with decreasing emissions from fossil fuel sources our inversion estimates unreasonably high emissions in other sources. Further, the inversion estimates a decrease in biomass-burning emissions that could explain falling ethane abundance. A range of sensitivity tests suggests that these results are robust.

  11. Atmospheric methane isotopic record favors fossil sources flat in 1980s and 1990s with recent increase

    NASA Astrophysics Data System (ADS)

    Rice, Andrew L.; Butenhoff, Christopher L.; Teama, Doaa G.; Röger, Florian H.; Khalil, M. Aslam K.; Rasmussen, Reinhold A.

    2016-09-01

    Observations of atmospheric methane (CH4) since the late 1970s and measurements of CH4 trapped in ice and snow reveal a meteoric rise in concentration during much of the twentieth century. Since 1750, levels of atmospheric CH4 have more than doubled to current globally averaged concentration near 1,800 ppb. During the late 1980s and 1990s, the CH4 growth rate slowed substantially and was near or at zero between 1999 and 2006. There is no scientific consensus on the drivers of this slowdown. Here, we report measurements of the stable isotopic composition of atmospheric CH4 (13C/12C and D/H) from a rare air archive dating from 1977 to 1998. Together with more modern records of isotopic atmospheric CH4, we performed a time-dependent retrieval of methane fluxes spanning 25 y (1984-2009) using a 3D chemical transport model. This inversion results in a 24 [18, 27] Tg y-1 CH4 increase in fugitive fossil fuel emissions since 1984 with most of this growth occurring after year 2000. This result is consistent with some bottom-up emissions inventories but not with recent estimates based on atmospheric ethane. In fact, when forced with decreasing emissions from fossil fuel sources our inversion estimates unreasonably high emissions in other sources. Further, the inversion estimates a decrease in biomass-burning emissions that could explain falling ethane abundance. A range of sensitivity tests suggests that these results are robust.

  12. Mechanism of Oxidation of Ethane to Ethanol at Iron(IV)-Oxo Sites in Magnesium-Diluted Fe2(dobdc).

    PubMed

    Verma, Pragya; Vogiatzis, Konstantinos D; Planas, Nora; Borycz, Joshua; Xiao, Dianne J; Long, Jeffrey R; Gagliardi, Laura; Truhlar, Donald G

    2015-05-06

    The catalytic properties of the metal-organic framework Fe2(dobdc), containing open Fe(II) sites, include hydroxylation of phenol by pure Fe2(dobdc) and hydroxylation of ethane by its magnesium-diluted analogue, Fe0.1Mg1.9(dobdc). In earlier work, the latter reaction was proposed to occur through a redox mechanism involving the generation of an iron(IV)-oxo species, which is an intermediate that is also observed or postulated (depending on the case) in some heme and nonheme enzymes and their model complexes. In the present work, we present a detailed mechanism by which the catalytic material, Fe0.1Mg1.9(dobdc), activates the strong C-H bonds of ethane. Kohn-Sham density functional and multireference wave function calculations have been performed to characterize the electronic structure of key species. We show that the catalytic nonheme-Fe hydroxylation of the strong C-H bond of ethane proceeds by a quintet single-state σ-attack pathway after the formation of highly reactive iron-oxo intermediate. The mechanistic pathway involves three key transition states, with the highest activation barrier for the transfer of oxygen from N2O to the Fe(II) center. The uncatalyzed reaction, where nitrous oxide directly oxidizes ethane to ethanol is found to have an activation barrier of 280 kJ/mol, in contrast to 82 kJ/mol for the slowest step in the iron(IV)-oxo catalytic mechanism. The energetics of the C-H bond activation steps of ethane and methane are also compared. Dehydrogenation and dissociation pathways that can compete with the formation of ethanol were shown to involve higher barriers than the hydroxylation pathway.

  13. Interannual, seasonal, and retrospective analysis of the methane and carbon dioxide budgets of a temperate peatland

    Treesearch

    D.M. Olson; T.J. Griffis; A. Noormets; R. Kolka; J. Chen

    2013-01-01

    Three years (2009-2011) of near-continuous methane (CH4) and carbon dioxide (CO2) fluxes were measured with the eddy covariance (EC) technique at a temperate peatland located within the Marcell Experimental Forest, in northern Minnesota, USA. The peatland was a net source of CH4 and a net sink of CO...

  14. Simulation and Characterization of Methane Hydrate Formation

    NASA Astrophysics Data System (ADS)

    Dhakal, S.; Gupta, I.

    2017-12-01

    The ever rising global energy demand dictates human endeavor to explore and exploit new and innovative energy sources. As conventional oil and gas reserves deplete, we are constantly looking for newer sources for sustainable energy. Gas hydrates have long been discussed as the next big energy resource to the earth. Its global occurrence and vast quantity of natural gas stored is one of the main reasons for such interest in its study and exploration. Gas hydrates are solid crystalline substances with trapped molecules of gas inside cage-like crystals of water molecules. Gases such as methane, ethane, propane and carbon dioxide can form hydrates but in natural state, methane hydrates are the most common. Subsurface geological conditions with high pressure and low temperature favor the formation and stability of gas hydrates. While the occurrence and potential of gas hydrates as energy source has long been studied, there are still gaps in knowledge, especially in the quantitative research of gas hydrate formation and reservoir characterization. This study is focused on exploring and understanding the geological setting in which gas hydrates are formed and the subsequent changes in rock characteristics as they are deposited. It involves the numerical simulation of methane gas flow through fault to form hydrates. The models are representative of the subsurface geologic setting of Gulf of Mexico with a fault through layers of shale and sandstone. Hydrate formation simulated is of thermogenic origin. The simulations are conducted using TOUGH+HYDRATE, a numerical code developed at the Lawrence Berkley National Laboratory for modeling multiphase flow through porous medium. Simulation results predict that as the gas hydrates form in the pores of the model, the porosity, permeability and other rock properties are altered. Preliminary simulation results have shown that hydrates begin to form in the fault zone and gradually in the sandstone layers. The increase in hydrate saturation is followed by decrease in the porosity and permeability of the reservoir rock. Sensitivities on flow rates of gas and water are simulated, using different reservoir properties, fault angles and grid sizes to study the properties of hydrate formation and accumulation in the subsurface.

  15. Annual net ecosystem exchanges of carbon dioxide and methane from a temperate brackish marsh: should the focus of marsh restoration be on brackish environments?

    NASA Astrophysics Data System (ADS)

    Windham-Myers, L.; Anderson, F. E.; Bergamaschi, B. A.; Ferner, M. C.; Schile, L. M.; Spinelli, G.

    2015-12-01

    The exchange and transport of carbon in tidally driven, saline marsh ecosystems provide habitat and trophic support for coastal wildlife and fisheries, while potentially accumulating and storing carbon at some of the highest rates compared to other ecosystems. However, due to the predicted rise in sea level over the next century, the preservation and restoration of estuarine habitats is necessary to compensate for their expected decline. In addition, restoration of these marsh systems can also reduce the impacts of global climate change as they assimilate as much carbon as their freshwater counterparts, while emitting less methane due to the higher concentrations of sulfate in seawater. Unfortunately, in brackish marshes, with salinity concentrations less than 18 parts per thousand (ppt), simple relationships between methane production, salinity and sulfate concentrations are not well known. Here we present the net ecosystem exchange (NEE) of carbon dioxide and methane, as calculated by the eddy covariance method, from a brackish marsh ecosystem in the San Francisco Estuary where salinity ranges from oligohaline (0.5-5 ppt) to mesohaline (5-18 ppt) conditions. Daily rates of carbon dioxide and methane NEE ranged from approximately 10 gC-CO2 m-2 d-1 and 0 mgC-CH4 m-2 d-1, during the winter to -15 gC-CO2 m-2 d-1 and 30 mgC-CH4 m-2 d-1, in the summer growing season. A comparison between similar measurements made from freshwater wetlands in the Sacramento-San Joaquin Delta found that the daily rates of carbon dioxide NEE were similar, but daily rates of methane NEE were just a small fraction (0-15%). Our research also shows that the daily fluxes of carbon dioxide and methane at the brackish marsh were highly variable and may be influenced by the tidal exchanges of seawater. Furthermore, the observed decline in methane production from summer to fall may have resulted from a rise in salinity and/or a seasonal decline in water and air temperatures. Our research goals are to provide insight into rates of plant productivity and uncertainty of methane production for brackish marsh systems that can help to inform policymakers of potential data gaps preventing inclusion of coastal wetland carbon sequestration in national inventories and greenhouse gas - offset markets.

  16. Measurements of Carbon Dioxide, Methane, and Other Related Tracers at High Spatial and Temporal Resolution in an Urban Environment

    NASA Astrophysics Data System (ADS)

    Yasuhara, Scott; Forgeron, Jeff; Rella, Chris; Franz, Patrick; Jacobson, Gloria; Chiao, Sen; Saad, Nabil

    2013-04-01

    The ability to quantify sources and sinks of carbon dioxide and methane on the urban scale is essential for understanding the atmospheric drivers to global climate change. In the 'top-down' approach, overall carbon fluxes are determined by combining remote measurements of carbon dioxide concentrations with complex atmospheric transport models, and these emissions measurements are compared to 'bottom-up' predictions based on detailed inventories of the sources and sinks of carbon, both anthropogenic and biogenic in nature. This approach, which has proven to be effective at continental scales, becomes challenging to implement at urban scales, due to poorly understood atmospheric transport models and high variability of the emissions sources in space (e.g., factories, highways, green spaces) and time (rush hours, factory shifts and shutdowns, and diurnal and seasonal variation in residential energy use). New measurement and analysis techniques are required to make sense of the carbon dioxide signal in cities. Here we present detailed, high spatial- and temporal- resolution greenhouse gas measurements made by multiple Picarro-CRDS analyzers in Silicon Valley in California. Real-time carbon dioxide data from a 20-month period are combined with real-time carbon monoxide, methane, and acetylene to partition the observed carbon dioxide concentrations between different anthropogenic sectors (e.g., transport, residential) and biogenic sources. Real-time wind rose data are also combined with real-time methane data to help identify the direction of local emissions of methane. High resolution WRF models are also included to better understand the dynamics of the boundary layer. The ratio between carbon dioxide and carbon monoxide is shown to vary over more than a factor of two from season to season or even from day to night, indicating rapid but frequent shifts in the balance between different carbon dioxide sources. Additional information is given by acetylene, a fossil fuel combustion tracer that provides complimentary information to carbon monoxide. In spring and summer, the combined signal of the urban center and the surrounding biosphere and urban green space is explored. These methods show great promise for identifying, quantifying, and partitioning urban-ecological (carbon) emissions.

  17. Improved enrichment culture technique for methane-oxidizing bacteria from marine ecosystems: the effect of adhesion material and gas composition.

    PubMed

    Vekeman, Bram; Dumolin, Charles; De Vos, Paul; Heylen, Kim

    2017-02-01

    Cultivation of microbial representatives of specific functional guilds from environmental samples depends largely on the suitability of the applied growth conditions. Especially the cultivation of marine methanotrophs has received little attention, resulting in only a limited number of ex situ cultures available. In this study we investigated the effect of adhesion material and headspace composition on the methane oxidation activity in methanotrophic enrichments obtained from marine sediment. Addition of sterilized natural sediment or alternatively the addition of acid-washed silicon dioxide significantly increased methane oxidation. This positive effect was attributed to bacterial adhesion on the particles via extracellular compounds, with a minimum amount of particles required for effect. As a result, the particles were immobilized, thus creating a stratified environment in which a limited diffusive gas gradients could build up and various microniches were formed. Such diffusive gas gradient might necessitate high headspace concentrations of CH 4 and CO 2 for sufficient concentrations to reach the methane-oxidizing bacteria in the enrichment culture technique. Therefore, high concentrations of methane and carbon dioxide, in addition to the addition of adhesion material, were tested and indeed further stimulated methane oxidation. Use of adhesion material in combination with high concentrations of methane and carbon dioxide might thus facilitate the cultivation and subsequent enrichment of environmentally important members of this functional guild. The exact mechanism of the observed positive effects on methane oxidation and the differential effect on methanotrophic diversity still needs to be explored.

  18. Understanding methane variability from 1980 - 2015 using inversions of methane, δ13C and ethane

    NASA Astrophysics Data System (ADS)

    Thompson, Rona; Nisbet, Euan

    2017-04-01

    Atmospheric methane (CH4) increased globally during the 20th century, from a pre-industrial value of approximately 722 ppb to 1773 ppb in 1999. The upward trend, however, was interrupted between 1999 and 2006, when the atmospheric growth rate of CH4 was close to zero. From 2007, atmospheric CH4 started to increase again and, in 2014, the growth rate was substantially faster (12.5 ppb/y) than in any other year since 2007. Changes in the atmospheric growth rate indicate changes in the balance of CH4 sources and sinks, however, the cause of the 1999-2006 stabilization and subsequent rise in atmospheric CH4, and its attribution to different sources is still not fully resolved. Various explanations have been proposed for the pause in the growth, including a reduction in fossil fuel and wetland emissions, and for its renewed increase, such as increasing emissions from wetlands, enteric fermentation, and fossil fuels, as well as a decline in the OH sink. To better constrain the sources and sinks of CH4, we have performed an inversion using the AGAGE 12-box model of the atmosphere using atmospheric observations of CH4, δ13C, and of ethane. Using observations of these 3 atmospheric tracers simultaneously, a stronger constraint is placed on the different sources, as well as the principal atmospheric sink via oxidation by OH. In the model, we account for all emissions grouped into microbial, fossil fuel, biomass burning, landfill and ocean sources, as well as the soil oxidation sink. We also account for the atmospheric sink of CH4 and ethane via oxidation by OH and Cl radicals. The modelled lifetimes of CH4 and ethane were 8.2 years and 1.3 months, respectively. Inversions were also performed in which the OH sink was optimized simultaneously with the emissions. We find that fossil fuel emissions were underestimated in the northern mid to high latitudes in the 1980s but were overestimated from the mid 1990s onwards with respect to the prior (EDGAR-4.2), and that there is no evidence for a recent increase. For microbial emissions, we find an increase in emissions in the northern low and high latitudes from the early 2000s. The inversion also shifts microbial emissions from the northern to the southern low latitudes with respect to the prior (LPX-Bern for wetlands and EDGAR-4.2 for enteric fermentation). Finally, we do not find any evidence for a recent decrease in the OH sink.

  19. Innovation in biological production and upgrading of methane and hydrogen for use as gaseous transport biofuel.

    PubMed

    Xia, Ao; Cheng, Jun; Murphy, Jerry D

    2016-01-01

    Biofuels derived from biomass will play a major role in future renewable energy supplies in transport. Gaseous biofuels have superior energy balances, offer greater greenhouse gas emission reductions and produce lower pollutant emissions than liquid biofuels. Biogas derived through fermentation of wet organic substrates will play a major role in future transport systems. Biogas (which is composed of approximately 60% methane/hydrogen and 40% carbon dioxide) requires an upgrading process to reduce the carbon dioxide content to less than 3% before it is used as compressed gas in transport. This paper reviews recent developments in fermentative biogas production and upgrading as a transport fuel. Third generation gaseous biofuels may be generated using marine-based algae via two-stage fermentation, cogenerating hydrogen and methane. Alternative biological upgrading techniques, such as biological methanation and microalgal biogas upgrading, have the potential to simultaneously upgrade biogas, increase gaseous biofuel yield and reduce carbon dioxide emission. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. Continuous catalytic decomposition of methane

    NASA Technical Reports Server (NTRS)

    Clifford, J. E.; Hillenbrand, L. J.; Kim, B. C.; Kolic, E. S.; Zupan, J.

    1973-01-01

    Water is conserved by employing sequence of reactions whereby 75 percent of methane from Sabatier reaction is decomposed to solid carbon and hydrogen; hydrogen is then separated from residual methane and utilized in usual Sabatier reaction to reduce remaining metabolic carbon dioxide.

  1. Utilization of heat from High Temperature Reactors (HTR) for dry reforming of methane

    NASA Astrophysics Data System (ADS)

    Jastrząb, Krzysztof

    2018-01-01

    One of the methods for utilization of waste carbon dioxide consists in reaction of methane with carbon dioxide, referred to as dry reforming of methane. It is an intensely endothermic catalytic process that takes place at the temperature above 700°C. Reaction of methane with carbon dioxide leads to formation of synthesis gas (syngas) that is a valuable chemical raw material. The energy that is necessary for the process to take place can be sourced from High Temperature Nuclear Reactors (HTR). The completed studies comprises a series of thermodynamic calculations and made it possible to establish optimum conditions for the process and demand for energy from HTR units. The dry reforming of methane needs also a catalytic agent with appropriate activity, therefore the hydrotalcite catalyser with admixture of cerium and nickel, developed at AGH University of Technology seems to be a promising solution. Thus, the researchers from the Institute for Chemical Processing of Coal (IChPW) in Zabrze have developed a methodology for production of the powdery hydrotalcite catalyser and investigated catalytic properties of the granulate obtained. The completed experiments confirmed that the new catalyser demonstrated high activity and is suitable for the process of methane dry reforming. In addition, optimum parameters of the were process (800°C, CO2:CH4 = 3:1) were established as well. Implementation of the technology in question into industrial practice, combined with utilization of HTR heat can be a promising method for management of waste carbon dioxide and may eventually lead to mitigation of the greenhouse effect.

  2. Solubility of crude oil in methane as a function of pressure and temperature

    USGS Publications Warehouse

    Price, L.C.; Wenger, L.M.; Ging, T.; Blount, C.W.

    1983-01-01

    The solubility of a 44?? API (0.806 sp. gr.) whole crude oil has been measured in methane with water present at temperatures of 50 to 250??C and pressures of 740 to 14,852 psi, as have the solubilities of two high molecular weight petroleum distillation fractions at temperatures of 50 to 250??C and pressures of 4482 to 25,266 psi. Both increases in pressure and temperature increase the solubility of crude oil and petroleum distillation fractions in methane, the effect of pressure being greater than that of temperature. Unexpectedly high solubility levels (0.5-1.5 grams of oil per liter of methane-at laboratory temperature and pressure) were measured at moderate conditions (50-200??C and 5076-14504 psi). Similar results were found for the petroleum distillation fractions, one of which was the highest molecular weight material of petroleum (material boiling above 266??C at 6 microns pressure). Unexpectedly mild conditions (100??C and 15,200 psi; 200??C and 7513 psi) resulted in cosolubility of crude oil and methane. Under these conditions, samples of the gas-rich phase gave solubility values of 4 to 5 g/l, or greater. Qualitative analyses of the crude-oil solute samples showed that at low pressure and temperature equilibration conditions, the solute condensate would be enriched in C5-C15 range hydrocarbons and in saturated hydrocarbons in the C15+ fraction. With increases in temperature and especially pressure, these tendencies were reversed, and the solute condensate became identical to the starting crude oil. The data of this study, compared to that of previous studies, shows that methane, with water present, has a much greater carrying capacity for crude oil than in dry systems. The presence of water also drastically lowers the temperature and pressure conditions required for cosolubility. The data of this and/or previous studies demonstrate that the addition of carbon dioxide, ethane, propane, or butane to methane also has a strong positive effect on crude oil solubility, as does the presence of fine grained rocks. The n-paraffin distributions (as well as the overall composition) of the solute condensates are controlled by the temperature and pressure of solution and exsolution, as well as by the composition of the original starting material. It appears quite possible that primary migration by gaseous solution could 'strip' a source rock of crude-oil like components leaving behind a bitumen totally unlike the migrated crude oil. The data of this study demonstrate previous criticisms of primary petroleum migration by gas solution are invalid; that primary migration by gaseous solution cannot occur because methane cannot dissolve sufficient volumes of crude oil or cannot dissolve the highest molecular weight components of petroleum (tars and asphaltenes). ?? 1983.

  3. Understanding the physiological and molecular mechanisms of rice-microbial interactions that produce methane

    USDA-ARS?s Scientific Manuscript database

    The second most abundant greenhouse gas, methane, is ~25 times more potent in global warming potential than carbon dioxide, and 7-17% of atmospheric methane comes from flooded rice fields. Methane emissions can be greatly reduced by using alternate wetting and drying irrigation management and/or cul...

  4. [Acclimatization and characteristics of microbial community in sulphate-dependent anaerobic methane oxidation].

    PubMed

    Xi, Jing-Ru; Liu, Su-Qin; Li, Lin; Liu, Jun-Xin

    2014-12-01

    The greenhouse effect of methane is 26 times worse than that of carbon dioxide, and wastewater containing high concentrations of sulfate is harmful to water, soil and plants. Therefore, anaerobic oxidation of methane driven by sulfate is one of the effective ways for methane reduction. In this paper, with sulfate as the electron accepter, a microbial consortium capable of oxidating methane under anaerobic condition was cultured. The diversity and characteristics of bacterial and archaeal community were investigated by PCR-DGGE, and phylogenetic analysis of the dominant microorganisms was also carried out. The DGGE fingerprints showed that microbial community structure changed distinctly, and the abundance of methane-oxidizing archea and sulfate-reducing bacteria increased in the acclimatization system added sulfate. After acclimatization, the bacterial diversity increased, while archaea diversity decreased slightly. The representative bands in the DGGE profiles were excised and sequenced. Results indicated that the dominant species in the acclimatization system were Spirochaetes, Desulfuromonadales, Methanosarcinales, Methanosaeta. Methane converted into carbon dioxide while sulfate transformed into hydrogen sulfide and sulfur in the process of anaerobic methane oxidation accompanied by sulphate reduction.

  5. Effect of forage to concentrate ratio in dairy cow diets on emission of methane, carbon dioxide and ammonia, lactation performance and manure excretion

    USDA-ARS?s Scientific Manuscript database

    Holstein cows housed in a modified tie-stall barn were used to determine the effect of feeding diets with different forage to concentrate ratios (F:C) on performance and emission of methane (CH4), carbon dioxide (CO2) and manure ammonia-nitrogen (NH3-N). Eight multiparous cows (means ± standard devi...

  6. The Delphic oracle: a multidisciplinary defense of the gaseous vent theory.

    PubMed

    Spiller, Henry A; Hale, John R; De Boer, Jelle Z

    2002-01-01

    Ancient historical references consistently describe an intoxicating gas, produced by a cavern in the ground, as the source of the power at the oracle of Delphi. These ancient writings are supported by a series of associated geological findings. Chemical analysis of the spring waters and travertine deposits at the site show these gases to be the light hydrocarbon gases methane, ethane, and ethylene. The effects of inhaling ethylene, a major anesthetic gas in the mid-20th century, are similar to those described in the ancient writings. We believe the probable cause of the trancelike state of the Priestess (the Pythia) at the oracle of Delphi during her mantic sessions was produced by inhaling ethylene gas or a mixture of ethylene and ethane from a naturally occurring vent of geological origin.

  7. Observation and simulation of ethane at 23 FTIR sites

    NASA Astrophysics Data System (ADS)

    Bader, W. M. J.; Mahieu, E.; Franco, B.; Pozzer, A.; Taraborrelli, D.; Prignon, M.; Servais, C. P.; De Maziere, M.; Vigouroux, C.; Mengistu Tsidu, G.; Sufa, G.; Mellqvist, J.; Blumenstock, T.; Hase, F.; Schneider, M.; Sussmann, R.; Nagahama, T.; Sudo, K.; Hannigan, J. W.; Ortega, I.; Morino, I.; Nakajima, H.; Smale, D.; Makarova, M.; Poberovsky, A.; Murata, I.; Grutter de la Mora, M.; Guarin, C. A.; Stremme, W.; Té, Y.; Jeseck, P.; Notholt, J.; Palm, M.; Conway, S. A.; Lutsch, E.; Strong, K.; Griffith, D. W. T.; Jones, N. B.; Paton-Walsh, C.; Friedrich, M.; Smeekes, S.

    2017-12-01

    Ethane is the most abundant non-methane hydrocarbon (NMHC) in the Earth atmosphere. Its main sources are of anthropogenic origin, with globally 62% from leakage during production and transport of natural gas, 20% from biofuel combustion and 18% from biomass burning. In the Southern hemisphere, anthropogenic emissions are lower which makes biomass burning emissions a more significant source. The main removal process is oxidation by the hydroxyl radical (OH), leading to a mean atmospheric lifetime of 2 months. Until recently, a prolonged decrease of its abundance has been documented, at rates of -1 to -2.7%/yr, with global emissions dropping from 14 to 11 Tg/yr over 1984-2010 owing to successful measures reducing fugitive emissions from its fossil fuel sources. However, subsequent investigations have reported on an upturn in the ethane trend, characterized by a sharp rise from about 2009 onwards. The ethane increase is attributed to the oil and natural gas production boom in North America, although significant changes in OH could also be at play. In the present contribution, we report the trend of ethane at 23 ground-based Fourier Transform Infrared (FTIR) sites spanning the 80ºN to 79ºS latitude range. Over 2010-2015, a significant ethane rise of 3-5%/yr is determined for most sites in the Northern Hemisphere, while for the Southern hemisphere the rates of changes are not significant at the 2-sigma uncertainty level . Dedicated model simulations by EMAC (ECHAM5/MESSy Atmospheric Chemistry; 1.8×1.8 degrees) implementing various emission scenarios are included in order to support data interpretation. The usual underestimation of the NMHCs emissions in the main inventories is confirmed here for RCP85 (Representative Concentration Pathway Database v8.5). Scaling them by 1.5 is needed to capture the background levels of atmospheric ethane. Moreover, additional and significant emissions ( 7 Tg over 2009-2015) are needed to capture the ethane rise in the Northern hemisphere. Attributing them to the oil and gas sector and locating them in North America allows EMAC to produce adequate trends in the Northern hemisphere, but not in the Southern hemisphere, where they are overestimated. Possible causes for this difference are discussed.

  8. Ethane C-C clumping in natural gas : a proxy for cracking processes ?

    NASA Astrophysics Data System (ADS)

    Clog, M. D.; Ferreira, A. A.; Santos Neto, E. V.; Eiler, J. M.

    2014-12-01

    Ethane (C2H6) is the second-most abundant alkane in most natural gas reservoirs, and is used to produce ethylene for petrochemical industries. It is arguably the simplest molecule that can manifest multiple 13C substitutions. There are several plausible controls on Δ13C2H6in natural gas: thermodynamically controlled homogeneous isotope exchange reactions analogous to those behind carbonate clumped isotope thermometry; inheritance from larger biomolecules that undergo thermal degradation to produce natural gas; mixing of natural gases that differ markedly in bulk isotopic composition; diffusive fractionation; or combinations of these and/or other, less expected fractionations. There is little basis for predicting which of these will control isotopic variations among natural ethanes, but we think it likely that addition of this new isotopic proxy will reveal new insights into the natural chemistry of ethane. We have developed a method to measure the abundance of 13C2H6 in natural samples, using high-resolution mass spectrometry. We define Δ13C2H6 as 1000 . ((13C2H6/12C2H6)measured/(13C2H6/12C2H6)stochastic -1). We studied several suites of natural gas samples and experimentally produced or modified ethane. Natural ethanes, including closely related samples from a single natural gas field, exhibit surprisingly large ranges in Δ13C2H6 (4 ‰ overall; up to 3 ‰ in one gas field). Such ranges cannot be explained by thermodynamic equilibrium at a range of different temperatures, or by diffusive fractionation. Kinetic isotope effects associated with 'cracking' reactions, and/or inheritance of non-equilibrium carbon isotope structures from source organics are more likely causes. We observe a correlation between Δ13C2H6 and the concentration of alkanes other than methane in several suites of natural gases, suggesting the causes of clumped isotope variations are tied to the controls on gas wetness. An experiment examining ethane residual to high-temperature pyrolysis confirms this trend could be an isotopic fingerprint for ethane destruction.

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

    Brauman, A.; Labat, M.; Kane, M.D.

    The evolution of different feeding guilds in termites is paralleled by differences in the activity of their gut microbiota. In wood-feeding termites, carbon dioxide-reducing acetogenic bacteria were found to generally outprocess carbon dioxide-reducing methanogenic bacteria for reductant (presumably hydrogen) generated during microbial fermentation in the hindgut. By contrast, acetogenesis from hydrogen and carbon dioxide was of little significance in fungus-growing and soil-feeding termites, which evolved more methane than their wood- and grass-feeding counterparts. Given the large biomass of termites on the earth and especially in the tropics, these findings should help refine global estimates of carbon dioxide reduction in anoxicmore » habitats and the contribution of termite emissions to atmospheric methane concentrations.« less

  10. In vitro laser decomposition of silicone fluid used in detachment of the retina.

    PubMed

    Huy, C P; Larricart, P; Warnet, J M; Haut, J

    1992-01-01

    The in vitro exposure of the silicone fluid Dimethicone 1,000 to radiation from the Nd:YAG laser results in the formation of transient breakdown gases which are composed mainly of methane, ethylene and traces of ethane, as identified by head-space gas chromatography. These hydrocarbons may interfere with the intra-ocular environment in the management of retinal detachment.

  11. Detailed Kinetic Mechanism of the Combustion of Homogeneous Gaseous Mixtures with Participation of Oxygen-containing Oxidants

    NASA Astrophysics Data System (ADS)

    Baevich, V. Ya

    1987-05-01

    The kinetic mechanisms of the oxidation and combustion of hydrogen, methane, methyl alcohol, acetylene, ethylene, ethane, and methylamine, using oxygen as well as hydrogen peroxide and nitric acid as oxidants, are discussed. The calculated and experimental data obtained under static conditions, in a flow, during flame propagation, and in shock tubes are compared. The bibliography includes 184 references.

  12. Shock synthesis of amino acids in simulated primitive environments.

    NASA Technical Reports Server (NTRS)

    Bar-Nun, A.; Bar-Nun, N.; Bauer, S. H.; Sagan, C.

    1971-01-01

    A single pulse shock tube of a uniform bore was used in the experiments. The reaction mixture consisted of 3.3 per cent methane, 11 per cent ethane, and 5.6 per cent ammonia, diluted with ultra-pure argon. The formation of glycine, alanine, valine, and leucine under conditions of shock heating was observed. Thermodynamic relations are discussed together with questions of conversion efficiency.

  13. Breath Analysis Using Laser Spectroscopic Techniques: Breath Biomarkers, Spectral Fingerprints, and Detection Limits

    PubMed Central

    Wang, Chuji; Sahay, Peeyush

    2009-01-01

    Breath analysis, a promising new field of medicine and medical instrumentation, potentially offers noninvasive, real-time, and point-of-care (POC) disease diagnostics and metabolic status monitoring. Numerous breath biomarkers have been detected and quantified so far by using the GC-MS technique. Recent advances in laser spectroscopic techniques and laser sources have driven breath analysis to new heights, moving from laboratory research to commercial reality. Laser spectroscopic detection techniques not only have high-sensitivity and high-selectivity, as equivalently offered by the MS-based techniques, but also have the advantageous features of near real-time response, low instrument costs, and POC function. Of the approximately 35 established breath biomarkers, such as acetone, ammonia, carbon dioxide, ethane, methane, and nitric oxide, 14 species in exhaled human breath have been analyzed by high-sensitivity laser spectroscopic techniques, namely, tunable diode laser absorption spectroscopy (TDLAS), cavity ringdown spectroscopy (CRDS), integrated cavity output spectroscopy (ICOS), cavity enhanced absorption spectroscopy (CEAS), cavity leak-out spectroscopy (CALOS), photoacoustic spectroscopy (PAS), quartz-enhanced photoacoustic spectroscopy (QEPAS), and optical frequency comb cavity-enhanced absorption spectroscopy (OFC-CEAS). Spectral fingerprints of the measured biomarkers span from the UV to the mid-IR spectral regions and the detection limits achieved by the laser techniques range from parts per million to parts per billion levels. Sensors using the laser spectroscopic techniques for a few breath biomarkers, e.g., carbon dioxide, nitric oxide, etc. are commercially available. This review presents an update on the latest developments in laser-based breath analysis. PMID:22408503

  14. CO2 Injection Into CH4 Hydrate Reservoirs: Quantifying Controls of Micro-Scale Processes

    NASA Astrophysics Data System (ADS)

    Bigalke, N. K.; Deusner, C.; Kossel, E.; Haeckel, M.

    2014-12-01

    The exchangeability of methane for carbon dioxide in gas hydrates opens the possibility of producing emission-neutral hydrocarbon energy. Recent field tests have shown that the production of natural gas from gas hydrates is feasible via injection of carbon dioxide into sandy, methane-hydrate-bearing sediment strata. Industrial-scale application of this method requires identification of thermo- and fluid-dynamic as well as kinetic controls on methane yield from and carbon dioxide retention within the reservoir. Extraction of gas via injection of carbon dioxide into the hydrate reservoir triggers a number of macroscopic effects, which are revealed for example by changes of the hydraulic conductivity and geomechanical stability. Thus far, due to analytical limitations, localized reactions and fluid-flow phenomena held responsible for these effects remain unresolved on the microscale (1 µm - 1 mm) and at near-natural reservoir conditions. We address this deficit by showing results from high-resolution, two-dimensional Raman spectroscopy mappings of an artificial hydrate reservoir during carbon dioxide injection under realistic reservoir conditions. The experiments allow us to resolve hydrate conversion rate and efficiency as well as activation of fluid pathways in space and time and their effect on methane yield, carbon-dioxide retention and hydraulic conductivity of the reservoir. We hypothesize that the conversion of single hydrate grains is a diffusion-controlled process which starts at the grain surface before continuing into the grain interior and show that the conversion can be modeled simply by using published permeation coefficients for CO2 and CH4 in hydrate and grain size as only input parameters.

  15. Organic matter in the Titan lakes, and comparison with primitive Earth

    NASA Astrophysics Data System (ADS)

    Khare, Bishun N.; McKay, C.; Wilhite, P.; Beeler, D.; Carter, M.; Schurmeier, L.; Jagota, S.; Kawai, J.; Nna-Mvondo, D.; Cruikshank, D.; Embaye, T.

    2013-06-01

    Titan is the only world in the solar system besides the Earth that has liquid on its surface. The liquid in the lakes is thought to be composed primarily of ethane with methane and nitrogen in solution. The clouds are thought to be composed of liquid methane drops. Surface liquid is present in polar lakes and in surface materials at equatorial sites. Studying the chemical processing that potentially results from organic material interacting with this liquid is one of the main goals of proposed missions to Titan. We have been engaged in producing tholin under Titan-like conditions for more than three decades, first at the Laboratory for Planetary Studies at Cornell University in collaboration with Late Dr. Carl Sagan and for over a decade at Laboratory for Planetary Studies at NASA Ames Research Center and Carl Sagan Center for the Study of Life in the Universe, SETI Institute. Our focus is to understand the capabilities for analysis of tholin solubility in liquid methane and ethane for flight instruments. Our results are expected to contribute to an understanding of the organic chemistry on Titan and to the development of an explicit and targeted scientific strategy for near term analysis of the products of organic-liquid interactions on Titan. Organics are produced as a haze in Titan's high atmosphere due to photolysis of methane with the Sun's extreme ultraviolet light and subsequent reaction with N. Also tholins are formed at a much higher level on Titan by charged particles of Saturn magnetosphere. However, the presence of organics is not the sole feature, which makes Titan significant to astrobiology; organics are widely present in the outer solar system. The reason Titan is a prime target for future outer solar system missions is the combination of organic material and liquid on the surface; liquid that could over a medium for further organic synthesis. NASA recently selected for further study a Discovery proposal TiME to investigate the chemistry of the lakes on Titan. As described by the team's press release: "The TiME capsule would launch in 2016 and reach Titan in 2023, parachuting onto the moon's second-largest northern sea, the Ligeia Mare. For 96 days the capsule would study the composition and behavior of the sea and its interaction with Titan's weather and climate. TiME would also seek evidence of the complex organic chemistry that may be active on Titan today, and that may be similar to processes that led to the development of life on the early Earth". The results of our on going research on how tholins interact with the liquid ethane and methane in the lakes on Titan will improve our chances of detecting any possible biology on this cold and distant world.

  16. Cyclic process for producing methane from carbon monoxide with heat removal

    DOEpatents

    Frost, Albert C.; Yang, Chang-lee

    1982-01-01

    Carbon monoxide-containing gas streams are converted to methane by a cyclic, essentially two-step process in which said carbon monoxide is disproportionated to form carbon dioxide and active surface carbon deposited on the surface of a catalyst, and said carbon is reacted with steam to form product methane and by-product carbon dioxide. The exothermic heat of reaction generated in each step is effectively removed during each complete cycle so as to avoid a build up of heat from cycle-to-cycle, with particularly advantageous techniques being employed for fixed bed, tubular and fluidized bed reactor operations.

  17. Cyclic process for producing methane in a tubular reactor with effective heat removal

    DOEpatents

    Frost, Albert C.; Yang, Chang-Lee

    1986-01-01

    Carbon monoxide-containing gas streams are converted to methane by a cyclic, essentially two-step process in which said carbon monoxide is disproportionated to form carbon dioxide and active surface carbon deposited on the surface of a catalyst, and said carbon is reacted with steam to form product methane and by-product carbon dioxide. The exothermic heat of reaction generated in each step is effectively removed during each complete cycle so as to avoid a build up of heat from cycle-to-cycle, with particularly advantageous techniques being employed for fixed bed, tubular and fluidized bed reactor operations.

  18. Hydrogenation of Carbon Dioxide to Methane by Ruthenium Nanoparticles in Ionic Liquid.

    PubMed

    Melo, Catarina I; Szczepańska, Anna; Bogel-Łukasik, Ewa; Nunes da Ponte, Manuel; Branco, Luís C

    2016-05-23

    The efficient transformation of carbon dioxide into fuels can be an excellent alternative to sequestration. In this work, we describe CO2 hydrogenation to methane in imidazolium-based ionic liquid media, using ruthenium nanoparticles prepared in situ as catalyst. The best yield of methane (69 %) was achieved using 0.24 mol % ruthenium catalyst (in [omim][NTf2 ], 1-octyl-3-methylimidazolium bistrifluoromethanesulfonylimide, at 40 bar of hydrogen pressure plus 40 bar of CO2 pressure, and at 150 °C. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. DISCOVERY OF FOG AT THE SOUTH POLE OF TITAN

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

    Brown, M. E.; Smith, A. L.; Chen, C.

    2009-11-20

    While Saturn's moon Titan appears to support an active methane hydrological cycle, no direct evidence for surface-atmosphere exchange has yet appeared. The indirect evidence, while compelling, could be misleading. It is possible, for example, that the identified lake features could be filled with ethane, an involatile long-term residue of atmospheric photolysis; the apparent stream and channel features could be ancient remnants of a previous climate; and the tropospheric methane clouds, while frequent, could cause no rain to reach the surface. We report here the detection of fog at the south pole of Titan during late summer using observations from themore » VIMS instrument on board the Cassini spacecraft. While terrestrial fog can form from a variety of causes, most of these processes are inoperable on Titan. Fog on Titan can only be caused by evaporation of nearly pure liquid methane; the detection of fog provides the first direct link between surface and atmospheric methane. Based on the detections presented here, liquid methane appears widespread at the south pole of Titan in late southern summer, and the hydrological cycle on Titan is currently active.« less

  20. Methane and nitrous oxide emissions from municipal wastewater treatment - results from a long-term study.

    PubMed

    Daelman, M R J; van Voorthuizen, E M; van Dongen, L G J M; Volcke, E I P; van Loosdrecht, M C M

    2013-01-01

    Methane and nitrous oxide emissions from a fully covered municipal wastewater treatment plant were measured on-line during 16 months. At the plant under study, nitrous oxide contributed three-quarters to the plant's carbon footprint, while the methane emission was slightly larger than the indirect carbon dioxide emission related to the plant's electricity and natural gas consumption. This contrasted with two other wastewater treatment plants, where more than 80% of the carbon footprint came from the indirect carbon dioxide emission. The nitrous oxide emission exhibited a seasonal dynamic, of which the cause remains unclear. Three types of air filter were investigated with regard to their effectiveness to remove methane from the off-gas.

  1. Nanoceria Supported Single-Atom Platinum Catalysts for Direct Methane Conversion

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

    Xie, Pengfei; Pu, Tiancheng; Nie, Anmin

    Nanoceria-supported atomic Pt catalysts (denoted as Pt 1@CeO 2) have been synthesized and demonstrated with advanced catalytic performance for the non-oxidative, direct conversion of methane. These catalysts were synthesized by calcination of Pt-impregnated porous ceria nanoparticles at high temperature (ca. 1,000 °C), with the atomic dispersion of Pt characterized by combining aberra-tion-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), X-ray photoelectron spectroscopy (XPS), X-ray absorption spec-troscopy (XAS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analyses. The Pt 1@CeO 2 catalysts exhibited much superior catalytic performance to its nanoparticulated counterpart, achieving 14.4% of methane conversion at 975 °C andmore » 74.6% selectivity toward C 2 products (ethane, ethylene and acetylene). Comparative studies of the Pt1@CeO 2 catalysts with different loadings as well as the nanoparticulated counterpart reveal the single-atom Pt to be the active sites for selective conversion of methane into C 2 hydrocarbons.« less

  2. Nanoceria Supported Single-Atom Platinum Catalysts for Direct Methane Conversion

    DOE PAGES

    Xie, Pengfei; Pu, Tiancheng; Nie, Anmin; ...

    2018-04-03

    Nanoceria-supported atomic Pt catalysts (denoted as Pt 1@CeO 2) have been synthesized and demonstrated with advanced catalytic performance for the non-oxidative, direct conversion of methane. These catalysts were synthesized by calcination of Pt-impregnated porous ceria nanoparticles at high temperature (ca. 1,000 °C), with the atomic dispersion of Pt characterized by combining aberra-tion-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), X-ray photoelectron spectroscopy (XPS), X-ray absorption spec-troscopy (XAS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) analyses. The Pt 1@CeO 2 catalysts exhibited much superior catalytic performance to its nanoparticulated counterpart, achieving 14.4% of methane conversion at 975 °C andmore » 74.6% selectivity toward C 2 products (ethane, ethylene and acetylene). Comparative studies of the Pt1@CeO 2 catalysts with different loadings as well as the nanoparticulated counterpart reveal the single-atom Pt to be the active sites for selective conversion of methane into C 2 hydrocarbons.« less

  3. Preliminary JIRAM results from Juno polar observations: 3. Evidence of diffuse methane presence in the Jupiter auroral regions

    NASA Astrophysics Data System (ADS)

    Moriconi, M. L.; Adriani, A.; Dinelli, B. M.; Fabiano, F.; Altieri, F.; Tosi, F.; Filacchione, G.; Migliorini, A.; Gérard, J. C.; Mura, A.; Grassi, D.; Sindoni, G.; Piccioni, G.; Noschese, R.; Cicchetti, A.; Bolton, S. J.; Connerney, J. E. P.; Atreya, S. K.; Bagenal, F.; Gladstone, G. R.; Hansen, C.; Kurth, W. S.; Levin, S. M.; Mauk, B. H.; McComas, D. J.; Turrini, D.; Stefani, S.; Olivieri, A.; Amoroso, M.

    2017-05-01

    Throughout the first orbit of the NASA Juno mission around Jupiter, the Jupiter InfraRed Auroral Mapper (JIRAM) targeted the northern and southern polar regions several times. The analyses of the acquired images and spectra confirmed a significant presence of methane (CH4) near both poles through its 3.3 μm emission overlapping the H3+ auroral feature at 3.31 μm. Neither acetylene (C2H2) nor ethane (C2H6) have been observed so far. The analysis method, developed for the retrieval of H3+ temperature and abundances and applied to the JIRAM-measured spectra, has enabled an estimate of the effective temperature for methane peak emission and the distribution of its spectral contribution in the polar regions. The enhanced methane inside the auroral oval regions in the two hemispheres at different longitude suggests an excitation mechanism driven by energized particle precipitation from the magnetosphere.

  4. Measurements of Carbon Dioxide, Methane, and Other Related Tracers at High Spatial and Temporal Resolution in an Urban Environment

    NASA Astrophysics Data System (ADS)

    Forgeron, J.; Yasuhara, S.; Rella, C.; Jacobson, G. A.; Chiao, S.

    2012-12-01

    Measurements of Carbon Dioxide, Methane, and Other Related Tracers at High Spatial and Temporal Resolution in an Urban Environment Jeff Forgeron1,2, Scott Yasuhara1,2, Chris Rella1, Gloria Jacobson1, Sen Chiao2 1Picarro Inc., 3105 Patrick Henry Drive, Santa Clara California 95054 USA 2San Jose State University, 1 Washington Square, San Jose California USA JeffAForgeron@gmail.com The ability to quantify sources and sinks of carbon dioxide and methane on the urban scale is essential for understanding the atmospheric drivers to global climate change. In the 'top-down' approach, overall carbon fluxes are determined by combining remote measurements of carbon dioxide concentrations with complex atmospheric transport models, and these emissions measurements are compared to 'bottom-up' predictions based on detailed inventories of the sources and sinks of carbon, both anthropogenic and biogenic in nature. This approach, which has proven to be effective at continental scales, becomes challenging to implement at urban scales, due to poorly understood atmospheric transport models and high variability of the emissions sources in space (e.g., factories, highways, green spaces) and time (rush hours, factory shifts and shutdowns, and diurnal and seasonal variation in residential energy use). New measurement and analysis techniques are required to make sense of the carbon dioxide signal in cities. Here we present detailed, high spatial- and temporal- resolution greenhouse gas measurements made by multiple Picarro-CRDS analyzers in Silicon Valley in California. Real-time carbon dioxide data from a 12-month period are combined with real-time carbon monoxide, methane, acetylene, and carbon-13 measurements to partition the observed carbon dioxide concentrations between different anthropogenic sectors (e.g., transport, residential) and biogenic sources. Real-time wind rose data are also combined with real-time methane data to help identify the direction of local emissions of methane. The ratio between carbon dioxide and carbon monoxide is shown to vary over more than a factor of two from season to season or even from day to night, indicating rapid but frequent shifts in the balance between different carbon dioxide sources. Additional information is given by the carbon-13 signature and by acetylene, a fossil fuel combustion tracer that provides complimentary information to carbon monoxide. In spring and summer, the combined signal of the urban center and the surrounding biosphere and urban green space is explored. These methods show great promise for identifying, quantifying, and partitioning urban-ecological (carbon) emissions. Figure 1: The left graph shows the change in diurnal cycle of CO2 (with the traffic signal removed) over a five month period. The right graph is the transit CO2 signal from weekdays and weekends, showing clear weekday enhancement of transit emissions.

  5. Sabatier Reactor System Integration with Microwave Plasma Methane Pyrolysis Post-Processor for Closed-Loop Hydrogen Recovery

    NASA Technical Reports Server (NTRS)

    Abney, Morgan B.; Miller, Lee A.; Williams, Tom

    2010-01-01

    The Carbon Dioxide Reduction Assembly (CRA) designed and developed for the International Space Station (ISS) represents the state-of-the-art in carbon dioxide reduction (CDRe) technology. The CRA produces water and methane by reducing carbon dioxide with hydrogen via the Sabatier reaction. The water is recycled to the Oxygen Generation Assembly (OGA) and the methane is vented overboard resulting in a net loss of hydrogen. The proximity to earth and the relative ease of logistics resupply from earth allow for a semi-closed system on ISS. However, long-term manned space flight beyond low earth orbit (LEO) dictates a more thoroughly closed-loop system involving significantly higher recovery of hydrogen, and subsequent recovery of oxygen, to minimize costs associated with logistics resupply beyond LEO. The open-loop ISS system for CDRe can be made closed-loop for follow-on missions by further processing methane to recover hydrogen. For this purpose, a process technology has been developed that employs a microwave-generated plasma to reduce methane to hydrogen and acetylene resulting in 75% theoretical recovery of hydrogen. In 2009, a 1-man equivalent Plasma Pyrolysis Assembly (PPA) was delivered to the National Aeronautics and Space Administration (NASA) for technical evaluation. The PPA has been integrated with a Sabatier Development Unit (SDU). The integrated process configuration incorporates a sorbent bed to eliminate residual carbon dioxide and water vapor in the Sabatier methane product stream before it enters the PPA. This paper provides detailed information on the stand-alone and integrated performance of both the PPA and SDU. Additionally, the integrated test stand design and anticipated future work are discussed.

  6. NOVEL MEMBRANE PROCESS TO UTILIZE DILUTE METHANE STREAMS - PHASE II

    EPA Science Inventory

    Methane is the second largest contributor to global warming after carbon dioxide. Various technologies and process improvements have been developed to curb methane emissions in...

  7. Carbon Dioxide Reduction Post-Processing Sub-System Development

    NASA Technical Reports Server (NTRS)

    Abney, Morgan B.; Miller, Lee A.; Greenwood, Zachary; Barton, Katherine

    2012-01-01

    The state-of-the-art Carbon Dioxide (CO2) Reduction Assembly (CRA) on the International Space Station (ISS) facilitates the recovery of oxygen from metabolic CO2. The CRA utilizes the Sabatier process to produce water with methane as a byproduct. The methane is currently vented overboard as a waste product. Because the CRA relies on hydrogen for oxygen recovery, the loss of methane ultimately results in a loss of oxygen. For missions beyond low earth orbit, it will prove essential to maximize oxygen recovery. For this purpose, NASA is exploring an integrated post-processor system to recover hydrogen from CRA methane. The post-processor, called a Plasma Pyrolysis Assembly (PPA) partially pyrolyzes methane to recover hydrogen with acetylene as a byproduct. In-flight operation of post-processor will require a Methane Purification Assembly (MePA) and an Acetylene Separation Assembly (ASepA). Recent efforts have focused on the design, fabrication, and testing of these components. The results and conclusions of these efforts will be discussed as well as future plans.

  8. Methane Post-Processor Development to Increase Oxygen Recovery beyond State-of-the-Art Carbon Dioxide Reduction Technology

    NASA Technical Reports Server (NTRS)

    Abney, Morgan; Miller, Lee; Greenwood, Zach; Iannantuono, Michelle; Jones, Kenny

    2013-01-01

    State-of-the-art life support carbon dioxide (CO2) reduction technology, based on the Sabatier reaction, is theoretically capable of 50% recovery of oxygen from metabolic CO2. This recovery is constrained by the limited availability of reactant hydrogen. Post-processing of the methane byproduct from the Sabatier reactor results in hydrogen recycle and a subsequent increase in oxygen recovery. For this purpose, a Methane Post-Processor Assembly containing three sub-systems has been developed and tested. The assembly includes a Methane Purification Assembly (MePA) to remove residual CO2 and water vapor from the Sabatier product stream, a Plasma Pyrolysis Assembly (PPA) to partially pyrolyze methane into hydrogen and acetylene, and an Acetylene Separation Assembly (ASepA) to purify the hydrogen product for recycle. The results of partially integrated testing of the sub-systems are reported.

  9. Methane Post-Processor Development to Increase Oxygen Recovery beyond State-of-the-Art Carbon Dioxide Reduction Technology

    NASA Technical Reports Server (NTRS)

    Abney, Morgan B.; Greenwood, Zachary; Miller, Lee A.; Alvarez, Giraldo; Iannantuono, Michelle; Jones, Kenny

    2013-01-01

    State-of-the-art life support carbon dioxide (CO2) reduction technology, based on the Sabatier reaction, is theoretically capable of 50% recovery of oxygen from metabolic CO2. This recovery is constrained by the limited availability of reactant hydrogen. Post-processing of the methane byproduct from the Sabatier reactor results in hydrogen recycle and a subsequent increase in oxygen recovery. For this purpose, a Methane Post-Processor Assembly containing three sub-systems has been developed and tested. The assembly includes a Methane Purification Assembly (MePA) to remove residual CO2 and water vapor from the Sabatier product stream, a Plasma Pyrolysis Assembly (PPA) to partially pyrolyze methane into hydrogen and acetylene, and an Acetylene Separation Assembly (ASepA) to purify the hydrogen product for recycle. The results of partially integrated testing of the sub-systems are reported

  10. Carbon and hydrogen isotopic reversals in deep basin gas: Evidence for limits to the stability of hydrocarbons

    USGS Publications Warehouse

    Burruss, R.C.; Laughrey, C.D.

    2010-01-01

    During studies of unconventional natural gas reservoirs of Silurian and Ordovician age in the northern Appalachian basin we observed complete reversal of the normal trend of carbon isotopic composition, such that ??13C methane (C1) >??13C ethane (C2) >??13C propane (C3). In addition, we have observed isotopic reversals in the ??2H in the deepest samples. Isotopic reversals cannot be explained by current models of hydrocarbon gas generation. Previous observations of partial isotopic reversals have been explained by mixing between gases from different sources and thermal maturities. We have constructed a model which, in addition to mixing, requires Rayleigh fractionation of C2 and C3 to cause enrichment in 13C and create reversals. In the deepest samples, the normal trend of increasing enrichment of 13C and 2H in methane with increasing depth reverses and 2H becomes depleted as 13C becomes enriched. We propose that the reactions that drive Rayleigh fractionation of C2 and C3 involve redox reactions with transition metals and water at late stages of catagenesis at temperatures on the order of 250-300??C. Published ab initio calculated fractionation factors for C-C bond breaking in ethane at these temperatures are consistent with our observations. The reversed trend in ??2H in methane appears to be caused by isotopic exchange with formation water at the same temperatures. Our interpretation that Rayleigh fractionation during redox reactions is causing isotopic reversals has important implications for natural gas resources in deeply buried sedimentary basins. ?? 2010.

  11. Carbon and hydrogen isotopic composition of methane and C2+ alkanes in electrical spark discharge: implications for identifying sources of hydrocarbons in terrestrial and extraterrestrial settings.

    PubMed

    Telling, Jon; Lacrampe-Couloume, Georges; Sherwood Lollar, Barbara

    2013-05-01

    The low-molecular-weight alkanes--methane, ethane, propane, and butane--are found in a wide range of terrestrial and extraterrestrial settings. The development of robust criteria for distinguishing abiogenic from biogenic alkanes is essential for current investigations of Mars' atmosphere and for future exobiology missions to other planets and moons. Here, we show that alkanes synthesized during gas-phase radical recombination reactions in electrical discharge experiments have values of δ(2)H(methane)>δ(2)H(ethane)>δ(2)H(propane), similar to those of the carbon isotopes. The distribution of hydrogen isotopes in gas-phase radical reactions is likely due to kinetic fractionations either (i) from the preferential incorporation of (1)H into longer-chain alkanes due to the more rapid rate of collisions of the smaller (1)H-containing molecules or (ii) by secondary ion effects. Similar δ(13)C(C1-C2+) and δ(2)H(C1-C2+) patterns may be expected in a range of extraterrestrial environments where gas-phase radical reactions dominate, including interstellar space, the atmosphere and liquid hydrocarbon lakes of Saturn's moon Titan, and the outer atmospheres of Jupiter, Saturn, Neptune, and Uranus. Radical recombination reactions at high temperatures and pressures may provide an explanation for the combined reversed δ(13)C(C1-C2+) and δ(2)H(C1-C2+) patterns of terrestrial alkanes documented at a number of high-temperature/pressure crustal sites.

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

    Waldhoff, Stephanie T.; Anthoff, David; Rose, Steven K.

    We use FUND 3.8 to estimate the social cost of four greenhouse gases: carbon dioxide, methane, nitrous oxide, and sulphur hexafluoride emissions. The damage potential for each gas—the ratio of the social cost of the non-carbon dioxide greenhouse gas to the social cost of carbon dioxide—is also estimated. The damage potentials are compared to several metrics, focusing in particular on the global warming potentials, which are frequently used to measure the trade-off between gases in the form of carbon dioxide equivalents. We find that damage potentials could be significantly higher than global warming potentials. This finding implies that previous papersmore » have underestimated the relative importance of reducing non-carbon dioxide greenhouse gas emissions from an economic damage perspective. We show results for a range of sensitivity analyses: carbon dioxide fertilization on agriculture productivity, terrestrial feedbacks, climate sensitivity, discounting, equity weighting, and socioeconomic and emissions scenarios. The sensitivity of the results to carbon dioxide fertilization is a primary focus as it is an important element of climate change that has not been considered in much of the previous literature. We estimate that carbon dioxide fertilization has a large positive impact that reduces the social cost of carbon dioxide with a much smaller effect on the other greenhouse gases. As a result, our estimates of the damage potentials of methane and nitrous oxide are much higher compared to estimates that ignore carbon dioxide fertilization. As a result, our base estimates of the damage potential for methane and nitrous oxide that include carbon dioxide fertilization are twice their respective global warming potentials. Our base estimate of the damage potential of sulphur hexafluoride is similar to the one previous estimate, both almost three times the global warming potential.« less

  13. Methanotrophic marine molluscan (Bivalvia, Mytilidae) symbiosis: mussels fueled by gas

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

    Childress, J.J.; Fisher, C.R.; Brooks, J.M.

    An undescribed mussel (family Mytilidae), which lives in the vicinity of hydrocarbon seeps in the Gulf of Mexico, consumes methane (the principal component of natural gas) at a high rate. The methane consumption is limited to the gills of these animals and is apparently due to the abundant intracellular bacteria found there. This demonstrates a methane-based symbiosis between an animal and intracellular bacteria. Methane consumption is dependent on the availability of oxygen and is inhibited by acetylene. The consumption of methane by these mussels is associated with a dramatic increase in oxygen consumption and carbon dioxide production. As the methanemore » consumption of the bivalve can exceed its carbide dioxide production, the symbiosis may be able to entirely satisfy its carbon needs from methane uptake. The very light (delta/sup 13/C = -51 to -57 per mil) stable carbon isotope ratios found in this animal support methane (delta/sup 13/C = -45 per mil at this site) as the primary carbon source for both the mussels and their symbionts. 19 references, 2 figures, 1 table.« less

  14. Global circulation as the main source of cloud activity on Titan

    USGS Publications Warehouse

    Rodriguez, S.; Le, Mouelic S.; Rannou, P.; Tobie, G.; Baines, K.H.; Barnes, J.W.; Griffith, C.A.; Hirtzig, M.; Pitman, K.M.; Sotin, Christophe; Brown, R.H.; Buratti, B.J.; Clark, R.N.; Nicholson, P.D.

    2009-01-01

    Clouds on Titan result from the condensation of methane and ethane and, as on other planets, are primarily structured by circulation of the atmosphere. At present, cloud activity mainly occurs in the southern (summer) hemisphere, arising near the pole and at mid-latitudes from cumulus updrafts triggered by surface heating and/or local methane sources, and at the north (winter) pole, resulting from the subsidence and condensation of ethane-rich air into the colder troposphere. General circulation models predict that this distribution should change with the seasons on a 15-year timescale, and that clouds should develop under certain circumstances at temperate latitudes (40??) in the winter hemisphere. The models, however, have hitherto been poorly constrained and their long-term predictions have not yet been observationally verified. Here we report that the global spatial cloud coverage on Titan is in general agreement with the models, confirming that cloud activity is mainly controlled by the global circulation. The non-detection of clouds at latitude 40??N and the persistence of the southern clouds while the southern summer is ending are, however, both contrary to predictions. This suggests that Titans equator-to-pole thermal contrast is overestimated in the models and that its atmosphere responds to the seasonal forcing with a greater inertia than expected. ?? 2009 Macmillan Publishers Limited. All rights reserved.

  15. iHWG-μNIR: a miniaturised near-infrared gas sensor based on substrate-integrated hollow waveguides coupled to a micro-NIR-spectrophotometer.

    PubMed

    Rohwedder, J J R; Pasquini, C; Fortes, P R; Raimundo, I M; Wilk, A; Mizaikoff, B

    2014-07-21

    A miniaturised gas analyser is described and evaluated based on the use of a substrate-integrated hollow waveguide (iHWG) coupled to a microsized near-infrared spectrophotometer comprising a linear variable filter and an array of InGaAs detectors. This gas sensing system was applied to analyse surrogate samples of natural fuel gas containing methane, ethane, propane and butane, quantified by using multivariate regression models based on partial least square (PLS) algorithms and Savitzky-Golay 1(st) derivative data preprocessing. The external validation of the obtained models reveals root mean square errors of prediction of 0.37, 0.36, 0.67 and 0.37% (v/v), for methane, ethane, propane and butane, respectively. The developed sensing system provides particularly rapid response times upon composition changes of the gaseous sample (approximately 2 s) due the minute volume of the iHWG-based measurement cell. The sensing system developed in this study is fully portable with a hand-held sized analyser footprint, and thus ideally suited for field analysis. Last but not least, the obtained results corroborate the potential of NIR-iHWG analysers for monitoring the quality of natural gas and petrochemical gaseous products.

  16. Separation of C2 hydrocarbons from methane in a microporous metal-organic framework

    NASA Astrophysics Data System (ADS)

    Tang, Fu-Shun; Lin, Rui-Biao; Lin, Rong-Guang; Zhao, John Cong-Gui; Chen, Banglin

    2018-02-01

    The recovery of C2 hydrocarbons including acetylene, ethylene and ethane is challenging but important for natural gas upgrading. The separation of C2 hydrocarbons over methane was demonstrated here by using a microporous metal-organic framework [Zn3(OH)2(SDB)2] (H2SDB = 4,4'-sulfonyldibenzoic acid) consisting narrow one-dimensional pore channels. Gas sorption experiments revealed that this MOF material showed considerable uptake capacity for C2H2, C2H4 and C2H6 under ambient conditions, while its capacity for CH4 was very low. High selectivity from IAST calculations for C2H2/CH4, C2H4/CH4 and C2H6/CH4 binary mixtures demonstrated that this MOF material were promising for efficiently separating important separation of C2 hydrocarbons from methane in natural gas processing.

  17. Infrared band intensities of saturated hydrocarbons

    NASA Technical Reports Server (NTRS)

    Pinkley, L. W.; Sethna, P. P.; Williams, D.

    1978-01-01

    Kramers-Kronig analysis is applied to measured values of spectral reflectance at near-normal incidence to determine the real and the imaginary parts of the complex index of refraction for methane, ethane, propane, n-butane, n-hexane, n-heptane, and n-decane in the liquid state. The results indicate that the strengths of the characteristic bands as measured by the integral of the imaginary part are roughly constant for all the liquid alkanes except for methane. The intensity of the CH valence vibration bands in the spectra of the alkanes except methane is directly proportional to the number of CH groups per unit volume. The relations for the intensity of the bands due to CH2 and CH3 deformations are examined. Characteristic band intensities of the type established for NH4(+) and SO4(2-) groups in solutions and crystals cannot be extended to the more closely coupled CH2 and CH3 groups in alkane molecules.

  18. Soil-atmosphere exchange of nitrous oxide, methane and carbon dioxide in a gradient of elevation in the coastal Brazilian Atlantic forest

    Treesearch

    E. Sousa Neto; J.B. Carmo; Michael Keller; S.C. Martins; L.F. Alves; S.A. Vieira; M.C. Piccolo; P. Camargo; H.T.Z. Couto; C.A. Joly; L.A. Martinelli

    2011-01-01

    Soils of tropical forests are important to the global budgets of greenhouse gases. The Brazilian Atlantic Forest is the second largest tropical moist forest area of South America, after the vast Amazonian domain. This study aimed to investigate the emissions of nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) fluxes along an altitudinal transect and the...

  19. Direct measurements of methane emissions from abandoned oil and gas wells in Pennsylvania

    PubMed Central

    Kang, Mary; Kanno, Cynthia M.; Reid, Matthew C.; Zhang, Xin; Mauzerall, Denise L.; Celia, Michael A.; Chen, Yuheng; Onstott, Tullis C.

    2014-01-01

    Abandoned oil and gas wells provide a potential pathway for subsurface migration and emissions of methane and other fluids to the atmosphere. Little is known about methane fluxes from the millions of abandoned wells that exist in the United States. Here, we report direct measurements of methane fluxes from abandoned oil and gas wells in Pennsylvania, using static flux chambers. A total of 42 and 52 direct measurements were made at wells and at locations near the wells (“controls”) in forested, wetland, grassland, and river areas in July, August, October 2013 and January 2014, respectively. The mean methane flow rates at these well locations were 0.27 kg/d/well, and the mean methane flow rate at the control locations was 4.5 × 10−6 kg/d/location. Three out of the 19 measured wells were high emitters that had methane flow rates that were three orders of magnitude larger than the median flow rate of 1.3 × 10−3 kg/d/well. Assuming the mean flow rate found here is representative of all abandoned wells in Pennsylvania, we scaled the methane emissions to be 4–7% of estimated total anthropogenic methane emissions in Pennsylvania. The presence of ethane, propane, and n-butane, along with the methane isotopic composition, indicate that the emitted methane is predominantly of thermogenic origin. These measurements show that methane emissions from abandoned oil and gas wells can be significant. The research required to quantify these emissions nationally should be undertaken so they can be accurately described and included in greenhouse gas emissions inventories. PMID:25489074

  20. Direct measurements of methane emissions from abandoned oil and gas wells in Pennsylvania.

    PubMed

    Kang, Mary; Kanno, Cynthia M; Reid, Matthew C; Zhang, Xin; Mauzerall, Denise L; Celia, Michael A; Chen, Yuheng; Onstott, Tullis C

    2014-12-23

    Abandoned oil and gas wells provide a potential pathway for subsurface migration and emissions of methane and other fluids to the atmosphere. Little is known about methane fluxes from the millions of abandoned wells that exist in the United States. Here, we report direct measurements of methane fluxes from abandoned oil and gas wells in Pennsylvania, using static flux chambers. A total of 42 and 52 direct measurements were made at wells and at locations near the wells ("controls") in forested, wetland, grassland, and river areas in July, August, October 2013 and January 2014, respectively. The mean methane flow rates at these well locations were 0.27 kg/d/well, and the mean methane flow rate at the control locations was 4.5 × 10(-6) kg/d/location. Three out of the 19 measured wells were high emitters that had methane flow rates that were three orders of magnitude larger than the median flow rate of 1.3 × 10(-3) kg/d/well. Assuming the mean flow rate found here is representative of all abandoned wells in Pennsylvania, we scaled the methane emissions to be 4-7% of estimated total anthropogenic methane emissions in Pennsylvania. The presence of ethane, propane, and n-butane, along with the methane isotopic composition, indicate that the emitted methane is predominantly of thermogenic origin. These measurements show that methane emissions from abandoned oil and gas wells can be significant. The research required to quantify these emissions nationally should be undertaken so they can be accurately described and included in greenhouse gas emissions inventories.

  1. What's a Fart?

    MedlinePlus

    ... side, the gas that makes soda fizzy), and methane (say: METH-ain) are made when food is ... bad. Tiny amounts of hydrogen, carbon dioxide, and methane combine with hydrogen sulfide (say: SUHL-fyde) and ...

  2. Plasma Pyrolysis Assembly Regeneration Evaluation

    NASA Technical Reports Server (NTRS)

    Medlen, Amber; Abney, Morgan B.; Miller, Lee A.

    2011-01-01

    In April 2010 the Carbon Dioxide Reduction Assembly (CRA) was delivered to the International Space Station (ISS). This technology requires hydrogen to recover oxygen from carbon dioxide. This results in the production of water and methane. Water is electrolyzed to provide oxygen to the crew. Methane is vented to space resulting in a loss of valuable hydrogen and unreduced carbon dioxide. This is not critical for ISS because of the water resupply from Earth. However, in order to have enough oxygen for long-term missions, it will be necessary to recover the hydrogen to maximize oxygen recovery. Thus, the Plasma Pyrolysis Assembly (PPA) was designed to recover hydrogen from methane. During operation, the PPA produces small amounts of carbon that can ultimately reduce performance by forming on the walls and windows of the reactor chamber. The carbon must be removed, although mechanical methods are highly inefficient, thus chemical methods are of greater interest. The purpose of this effort was to determine the feasibility of chemically removing the carbon from the walls and windows of a PPA reactor using a pure carbon dioxide stream.

  3. Root biomass as a major means of affecting methane emissions

    USDA-ARS?s Scientific Manuscript database

    Human activities are contributing to greenhouse gas emissions. Methane, the second most abundant greenhouse gas, is ~25 times more potent in global warming potential than carbon dioxide, and 7-17% of atmospheric methane comes from paddy rice fields. The purpose of the study was to investigate gene...

  4. Evaluation of Genetic Variation in Rice to Mitigate Methane Emissions

    USDA-ARS?s Scientific Manuscript database

    Agriculture is recognized as a significant contributor to greenhouse gas emissions (GHGE) globally. Paddy rice is a significant source of methane emissions. Methane accounts for about 11% of all U.S. GHGE and it is ~25 times more potent in global warming potential than carbon dioxide. Research has s...

  5. New Wind in Old Sails: Novel Applications of Triphos-based Transition Metal Complexes as Homogeneous Catalysts for Small Molecules and Renewables Activation.

    PubMed

    Mellone, Irene; Bertini, Federica; Gonsalvi, Luca; Guerriero, Antonella; Peruzzini, Maurizio

    2015-01-01

    Recent developments in the coordination chemistry and applications of Ru-triphos [triphos = 1,1,1-tris-(diphenylphosphinomethyl)ethane] systems are reviewed, highlighting their role as active and selective homogenous catalysts for small molecule activation, biomass conversions and in carbon dioxide utilization-related processes.

  6. EFFECTS OF CULTURE PARAMETERS ON DDT [1,1,1-TRICHLO- RO-2,2-BIS(4-CHLOROPHENYL) ETHANE] BIODEGRADATION BY PHANEROCHAETE CHRYSOSPORIUM

    EPA Science Inventory

    The lignin degrading system of the white rot fungus Phanerochaete chrysosporium is able to degrade a wide variety of structurally diverse organopollutants to carbon dioxide. Current research is focused on ways to increase or optimize rates of biodegradation in order to a...

  7. Gas geochemistry of the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope: implications for gas hydrate exploration in the Arctic

    USGS Publications Warehouse

    Lorenson, T.D.; Collett, T.S.; Hunter, R.B.

    2011-01-01

    Gases were analyzed from well cuttings, core, gas hydrate, and formation tests at the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well, drilled within the Milne Point Unit, Alaska North Slope. The well penetrated a portion of the Eileen gas hydrate deposit, which overlies the more deeply buried Prudhoe Bay, Milne Point, West Sak, and Kuparuk River oil fields. Gas sources in the upper 200 m are predominantly from microbial sources (C1 isotopic compositions ranging from −86.4 to −80.6‰). The C1 isotopic composition becomes progressively enriched from 200 m to the top of the gas hydrate-bearing sands at 600 m. The tested gas hydrates occur in two primary intervals, units D and C, between 614.0 m and 664.7 m, containing a total of 29.3 m of gas hydrate-bearing sands. The hydrocarbon gases in cuttings and core samples from 604 to 914 m are composed of methane with very little ethane. The isotopic composition of the methane carbon ranges from −50.1 to −43.9‰ with several outliers, generally decreasing with depth. Gas samples collected by the Modular Formation Dynamics Testing (MDT) tool in the hydrate-bearing units were similarly composed mainly of methane, with up to 284 ppm ethane. The methane isotopic composition ranged from −48.2 to −48.0‰ in the C sand and from −48.4 to −46.6‰ in the D sand. Methane hydrogen isotopic composition ranged from −238 to −230‰, with slightly more depleted values in the deeper C sand. These results are consistent with the concept that the Eileen gas hydrates contain a mixture of deep-sourced, microbially biodegraded thermogenic gas, with lesser amounts of thermogenic oil-associated gas, and coal gas. Thermal gases are likely sourced from existing oil and gas accumulations that have migrated up-dip and/or up-fault and formed gas hydrate in response to climate cooling with permafrost formation.

  8. Project identification for methane reduction options

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

    Kerr, T.

    1996-12-31

    This paper discusses efforts directed at reduction in emission of methane to the atmosphere. Methane is a potent greenhouse gas, which on a 20 year timeframe may present a similar problem to carbon dioxide. In addition, methane causes additional problems in the form of smog and its longer atmospheric lifetime. The author discusses strategies for reducing methane emission from several major sources. This includes landfill methane recovery, coalbed methane recovery, livestock methane reduction - in the form of ruminant methane reduction and manure methane recovery. The author presents examples of projects which have implemented these ideas, the economics of themore » projects, and additional gains which come from the projects.« less

  9. Emissions of volatile organic compounds (VOCs) from oil and natural gas activities: compositional comparison of 13 major shale basins via NOAA airborne measurements

    NASA Astrophysics Data System (ADS)

    Gilman, J.; Lerner, B. M.; Aikin, K. C.; De Gouw, J. A.; Koss, A.; Yuan, B.; Warneke, C.; Peischl, J.; Ryerson, T. B.; Holloway, J. S.; Graus, M.; Tokarek, T. W.; Isaacman-VanWertz, G. A.; Sueper, D.; Worsnop, D. R.

    2015-12-01

    The recent and unprecedented increase in natural gas production from shale formations is associated with a rise in the production of non-methane volatile organic compounds (VOCs) including natural gas plant liquids (e.g., ethane, propane, and butanes) and liquid lease condensate (e.g., pentanes, hexanes, aromatics and cycloalkanes). Since 2010, the production of natural gas liquids and the amount of natural gas vented/flared has increased by factors of ~1.28 and 1.57, respectively (U.S. Energy and Information Administration), indicating an increasingly large potential source of hydrocarbons to the atmosphere. Emission of VOCs may affect local and regional air quality due to the potential to form tropospheric ozone and organic particles as well as from the release of toxic species such as benzene and toluene. The 2015 Shale Oil and Natural Gas Nexus (SONGNex) campaign studied emissions from oil and natural gas activities across the central United States in order to better understand their potential air quality and climate impacts. Here we present VOC measurements from 19 research flights aboard the NOAA WP-3D over 11 shale basins across 8 states. Non-methane hydrocarbons were measured using an improved whole air sampler (iWAS) with post-flight analysis via a custom-built gas chromatograph-mass spectrometer (GC-MS). The whole air samples are complimented by higher-time resolution measurements of methane (Picarro spectrometer), ethane (Aerodyne spectrometer), and VOCs (H3O+ chemical ionization mass spectrometer). Preliminary analysis show that the Permian Basin on the New Mexico/Texas border had the highest observed VOC mixing ratios for all basins studied. We will utilize VOC enhancement ratios to compare the composition of methane and VOC emissions for each basin and the associated reactivities of these gases with the hydroxyl radical, OH, as a proxy for potential ozone formation.

  10. Abiotic vs biological sources and fates of organic compounds in a low temperature continental serpentinizing system

    NASA Astrophysics Data System (ADS)

    Robinson, K.; Noble, S. M.; Shock, E.

    2016-12-01

    Serpentinization is likely the most common water-rock reaction in our solar system. During this process ultramafic silicates are hydrated, a calcium hydroxide solution is formed, and H2O is reduced to H2 coupled to the oxidation of Fe2+ to Fe3+. The resulting hyper-alkaline, reduced conditions generate thermodynamic drives for numerous carbon compound reactions, including the precipitation of various carbonate minerals and the reduction of inorganic carbonate to organic carbon. Testing the extent to which these thermodynamic drives lead to observable results led to the present study of the flow and transformations of carbon through the active continental serpentinizing system at the Samail Ophiolite in the Sultanate of Oman. Water samples were collected from shallow groundwater (representing system input), hyper-alkaline seeps (system output), boreholes (system intermediate), and surface fluid mixing zones, and analyzed for concentrations of dissolved inorganic carbon (DIC + δ13C), organic carbon (+ δ13C), formate, acetate, H2, methane (+ δ13C), ethane, and an accompanying suite of other geochemical solutes. These analyses indicate that the vast majority of DIC in these serpentinizing fluids precipitates in the subsurface as carbonate minerals; however, a significant amount of DIC is converted into organic acids and light hydrocarbons and expelled at the surface in hyper-alkaline seeps. Based on thermodynamic calculations, it seems most likely that formate last equilibrated with dolomite (CaMg[CO3]2) in the subsurface, acetate last equilibrated with calcite (CaCO3) near the surface, and methane and ethane last equilibrated in a distinct carbon-limited region of the subsurface. As for the fates of these compounds, energetic calculations reveal that a combination of oxidative, reductive, and fermentative metabolisms are thermodynamically favorable. Indeed, δ13C trends record microbial methane oxidation at the surface and cannot rule out methane as biologically sourced from the subsurface.

  11. Near-surface gas mapping studies of salt geologic features at Weeks Island and other sites

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

    Molecke, M.A.; Carney, K.R.; Autin, W.J.

    1996-10-01

    Field sampling and rapid gas analysis techniques were used to survey near-surface soil gases for geotechnical diagnostic purposes at the Weeks Island Strategic Petroleum Reserve (SPR) site and other salt dome locations in southern Louisiana. This report presents the complete data, results and interpretations obtained during 1995. Weeks Island 1994 gas survey results are also briefly summarized; this earlier study did not find a definitive correlation between sinkhole No. 1 and soil gases. During 1995, several hundred soil gas samples were obtained and analyzed in the field by gas chromatography, for profiling low concentrations and gas anomalies at ppm tomore » percent levels. The target gases included hydrogen, methane, ethane and ethylene. To supplement the field data, additional gas samples were collected at various site locations for laboratory analysis of target gases at ppb levels. Gases in the near-surface soil originate predominantly from the oil, from petrogenic sources within the salt, or from surface microbial activity. Surveys were conducted across two Weeks Island sinkholes, several mapped anomalous zones in the salt, and over the SPR repository site and its perimeter. Samples were also taken at other south Louisiana salt dome locations for comparative purposes. Notable results from these studies are that elevated levels of hydrogen and methane (1) were positively associated with anomalous gassy or shear zones in the salt dome(s) and (2) are also associated with suspected salt fracture (dilatant) zones over the edges of the SPR repository. Significantly elevated areas of hydrogen, methane, plus some ethane, were found over anomalous shear zones in the salt, particularly in a location over high pressure gas pockets in the salt, identified in the mine prior to SPR operations. Limited stable isotope ratio analyses, SIRA, were also conducted and determined that methane samples were of petrogenic origin, not biogenic.« less

  12. Revising Estimates of the Methane Production Pathway in Peatland Porewater Using Intramolecular Isotopic Analyses of Acetate

    NASA Astrophysics Data System (ADS)

    Thomas, B.; Arthur, M. A.; Freeman, K. H.

    2007-12-01

    Stable isotopic measurements of methane and carbon dioxide are routinely applied to environmental samples to assess the relative importance of methane production by either aceticlastic or hydrogenotrophic methanogenesis. Such estimates rely upon assumptions about isotopic fractionation during methane production and oxidation. Rigorous isotope-based pathway estimates require knowledge of the carbon isotopic composition of both carbon dioxide and acetate. In practice, technical barriers have limited measurements of the isotopic composition of whole acetate in natural samples. Yet, the estimate of whole acetate isotopic values, even when available, may not represent accurately the composition of the methyl carbon, which is, in fact, the precursor to methane. It is exceedingly rare to find carbon isotopic measurements of acetate-methyl in the literature, and, to our knowledge, the d13C of the acetate-methyl precursor to methane has never before been reported from peatland porewater samples. Extremely 13C-depleted methane, -70 permil VPDB, and 13C-enriched carbon dioxide from acidic northern peat bogs are typically interpreted as signatures of hydrogenotrophic methanogenesis. The hypothesized dominance of methane production from hydrogen in acidic bogs contrasts with the vast majority of freshwater wetlands in which aceticlastic methanogenesis dominates. Using a new technique for the online analysis of the intramolecular carbon isotopic composition of acetate in natural samples, we find the acetate-methyl in peat porewaters can be significantly depleted relative to bulk organic matter. In porewater profiles from both winter and summer, acetate is as much as 15 permil depleted relative to bulk carbon. We hypothesize that acetate- methyl isotopic depletion results from conditions that favor autotrophic acetogenesis and subsequent acetate consumption by aceticlastic methanogens. Porewater depth profiles during winter and summer illustrate depth- dependent increases in the fraction of methane derived from carbon dioxide, with deeper peat dominated by hydrogenotrophic methanogenesis, but shallow peat dominated by aceticlastic methanogens. Significant aceticlastic methane production from autotrophically produced acetate challenges the ability of hydrogen isotopic measurements of methane to represent the pathway of methanogenesis. Supplementing our field observations, intramolecular acetate measurements of incubation experiments confirm that an aceticlastic methanogen can facilitate significant acetate-carboxyl exchange with DIC. This novel technique confirms two caveats associated with whole acetate carbon isotopic data: 1, the carboxyl carbon isotopic composition may not accurately reflect the composition of the parent molecule, and 2, the acetate methyl may be derived from inorganic carbon or the fractionation effect of fermentation in acidic porewaters may be significant.

  13. Effect of frame size and season on enteric methane (CH4) and carbon dioxide (CO2)emissions in Angus brood cows grazing native tall-grass prairie in central Oklahoma USA

    USDA-ARS?s Scientific Manuscript database

    Effect of frame size and season on enteric methane (CH4) and carbon dioxide (CO2) emissions in Angus brood cows grazing native tall-grass prairie in central Oklahoma, USA J.P.S. Neel USDA ARS, El Reno, OK A reduction in enteric CH4 production in ruminants is associated with improved production effic...

  14. The Biogeochemistry of Seattle's Urban Streams

    NASA Astrophysics Data System (ADS)

    Yonemura, R.

    2016-12-01

    Urban development is underway at an unprecedented pace in the city of Seattle, WA. What were once productive salmon spawning ecosystems are now highly altered ecosystems that reflect the impacts of human land-use change. However, the impact that these changes have had on the carbon biogeochemistry have not been studied. We investigate the biogeochemical properties over time of two urban streams in Seattle; Ravenna Creek, an urban park and closed network, and Thornton Creek, a recently day-lighted and restored stream network. We conducted a longitudinal sampling along each of these creeks from their headwaters down to their confluences with Lake Washington. Our data suggest that these systems are supersaturated in both dissolved carbon dioxide and dissolved methane. Preliminary results reveal that carbon dioxide and methane are both highest at the end of Ravenna Creek located on the surface of a preexisting landfill. The highest carbon dioxide and methane levels on Thornton Creek are located at the uppermost site and the site directly below a golf course. These findings suggest that local land-use has an impact on the concentrations of dissolved gases in the surrounding water bodies with implications for urban streams as localized sources of carbon dioxide and methane to the atmosphere. Additional data on nutrients and stream metabolism will highlight the consistency of these gas concentrations over time, and provide an additional indicator into the health of these urban systems.

  15. Optimal Estimation Retrieval of Mid-Tropospheric Carbon Dioxide and Methane Using the Atmospheric Infrared Sounder (AIRS) Radiances.

    NASA Astrophysics Data System (ADS)

    Imbiriba, B.

    2017-12-01

    Carbon dioxide and methane are the most important anthropogenic greenhouse contributions to climate change. Space-based remote sensing measurements of carbon dioxide and methane would help to understand the generation, absorption and transport mechanisms and characterization of such gases. Space-based hyperspectral thermal infrared remote sensing measurements using NASA's Atmospheric Infrared Sounder (AIRS) instrument can provide 14 years of observations of radiances at the top of the atmosphere.Here we present a Optimal Estimation based retrieval system for surface temperature, water vapor, carbon dioxide, methane, and other trace gases, based on selected AIRS channels that allow for CO2 sensitivity down to the lower part of the middle troposphere. We use the SARTA fast forward model developed at University of Maryland Baltimore County, and use the ERA product for prior state atmospheric profiles.We retrieve CO2 and CH4 column concentrations across 14 years of AIRS measurements, for clear only field-of-views, using the AIRS L1B Calibration Subset. We then compare these to the standard AIRS L2 CO2 retrievals, as well TES, and OCO2 data, and the GlobalView/CarbonTracker CO2/CH4 model data from NOAA. We evaluate the hemispheric seasonal cycles, growth rates, and possible interhemispheric transport. We also evaluate the use of atmospheric nitrous oxide concentration to correct for the errors in the temperature profile.

  16. Methyl-coenzyme M reductase from methanogenic archaea: isotope effects on label exchange and ethane formation with the homologous substrate ethyl-coenzyme M.

    PubMed

    Scheller, Silvan; Goenrich, Meike; Thauer, Rudolf K; Jaun, Bernhard

    2013-10-09

    Ethyl-coenzyme M (CH3CH2-S-CH2CH2-SO3(-), Et-S-CoM) serves as a homologous substrate for the enzyme methyl-coenzyme M reductase (MCR) resulting in the product ethane instead of methane. The catalytic reaction proceeds via an intermediate that already contains all six C-H bonds of the product. Because product release occurs after a second, rate-limiting step, many cycles of intermediate formation and reconversion to substrate occur before a substantial amount of ethane is released. In deuterated buffer, the intermediate becomes labeled, and C-H activation in the back reaction rapidly leads to labeled Et-S-CoM, which enables intermediate formation to be detected. Here, we present a comprehensive analysis of this pre-equilibrium. (2)H- and (13)C-labeled isotopologues of Et-S-CoM were used as the substrates, and the time course of each isotopologue was followed by NMR spectroscopy. A kinetic simulation including kinetic isotope effects allowed determination of the primary and α- and β-secondary isotope effects for intermediate formation and for the C-H/C-D bond activation in the ethane-containing intermediate. The values obtained are in accordance with those found for the native substrate Me-S-CoM (see preceding publication, Scheller, S.; Goenrich, M.; Thauer, R. K.; Jaun, B. J. Am. Chem. Soc. 2013, 135, DOI: 10.1021/ja406485z) and thus imply the same catalytic mechanism for both substrates. The experiment by Floss and co-workers, demonstrating a net inversion of configuration to chiral ethane with CH3CDT-S-CoM as the substrate, is compatible with the observed rapid isotope exchange if the isotope effects measured here are taken into account.

  17. Determining the Local Abundance of Martian Methane and its 13-C/l2-C and D/H Isotopic Ratios for Comparison with Related Gas and Soil Analysis on the 2011 Mars Science Laboratory (MSL) Mission

    NASA Technical Reports Server (NTRS)

    Webster, Christopher R.; Mahaffy, Paul R.

    2011-01-01

    Understanding the origin of Martian methane will require numerous complementary measurements from both in situ and remote sensing investigations and laboratory work to correlate planetary surface geophysics with atmospheric dynamics and chemistry. Three instruments (Quadrupole Mass Spectrometer (QMS), Gas Chromatograph (GC) and Tunable Laser Spectrometer (TLS)) with sophisticated sample handling and processing capability make up the Sample Analysis at Mars (SAM) analytical chemistry suite on NASA s 2011 Mars Science Laboratory (MSL) Mission. Leveraging off the SAM sample and gas processing capability that includes methane enrichment, TLS has unprecedented sensitivity for measuring absolute methane (parts-per-trillion), water, and carbon dioxide abundances in both the Martian atmosphere and evolved from heated soil samples. In concert with a wide variety of associated trace gases (e.g. SO2, H2S, NH3, higher hydrocarbons, organics, etc.) and other isotope ratios measured by SAM, TLS will focus on determining the absolute abundances of methane, water and carbon dioxide, and their isotope ratios: 13C/12C and D/H in methane; 13C/12C and 18O/17O/16O in carbon dioxide; and 18O/17O/16O and D/H in water. Measurements near the MSL landing site will be correlated with satellite (Mars Express, Mars 2016) and ground-based observations.

  18. Cometabolism of DDT analogs by a Pseudomonas sp.

    PubMed Central

    Francis, A J; Spanggord, R J; Ouchi, G I; Bohonos, N

    1978-01-01

    A Pseudomonas sp. capable of growth on several nonchlorinated and mono-p-chloro-substituted analogs of DDT as a sole carbon source degraded bis(p-chlorophenyl)methane and 1,1-bis(p-chlorophenyl)ethane only in the presence of diphenylethane. The products p-chlorophenylacetic acid and 2-(p-chlorophenyl)-propionic acid were not further metabolized by the bacterium. Other chlorinated analogs of DDT were found to be recalcitrant to cometabolic degradation with diphenylethane. PMID:637537

  19. Asymmetric hydrogenation of α,β-unsaturated phosphonates with Rh-BisP* and Rh-MiniPHOS catalysts: Scope and mechanism of the reaction

    PubMed Central

    Gridnev, Ilya D.; Yasutake, Masaya; Imamoto, Tsuneo; Beletskaya, Irina P.

    2004-01-01

    Optically active 1,2-bis(alkylmethylphosphino)ethanes and bis(alkylmethylphosphino)methanes are unique diphosphine ligands combining the simple molecular structure and P-stereogenic asymmetric environment. This work shows that these ligands exhibit excellent enantioselectivity in rhodium-catalyzed asymmetric hydrogenation of α,β-unsaturated phosphonic acid derivatives. The enantioselective hydrogenation mechanism elucidated by NMR study is also described. PMID:15024119

  20. Fundamental Flame Velocities of Pure Hydrocarbons I : Alkanes, Alkenes, Alkynes Benzene, and Cyclohexane

    NASA Technical Reports Server (NTRS)

    Gerstein, Melvin; Levine, Oscar; Wong, Edgar L

    1950-01-01

    The flame velocities of 37 pure hydrocarbons including normal and branched alkanes, alkenes, and alkynes; as well as benzene and cyclohexane, together with the experimental technique employed are presented. The normal alkanes have about the same flame velocity from ethane through heptane with methane being about 16 percent lower. Unsaturation increases the flame velocity in the order of alkanes, alkenes, and alkynes. Branching reduces the flame velocity.

  1. Highly Selective Membranes For The Separation Of Organic Vapors Using Super-Glassy Polymers

    DOEpatents

    Pinnau, Ingo; Lokhandwala, Kaaeid; Nguyen, Phuong; Segelke, Scott

    1997-11-18

    A process for separating hydrocarbon gases of low boiling point, particularly methane, ethane and ethylene, from nitrogen. The process is performed using a membrane made from a super-glassy material. The gases to be separated are mixed with a condensable gas, such as a C.sub.3+ hydrocarbon. In the presence of the condensable gas, improved selectivity for the low-boiling-point hydrocarbon gas over nitrogen is achieved.

  2. Hydrogen Migration and Vinylidene Pathway for Formation of Methane in the 193 nm Photodissociation of Propene: CH3CH=CH2 and CD3CD=CD2

    NASA Technical Reports Server (NTRS)

    Zhao, Yi-Lei; Laufer, Allan H.; Halpern, Joshua B.; Fahr, Askar

    2007-01-01

    Photodissociation channels and the final product yields from the 193 nm photolysis of propene-h6 (CH2=CHCH3) and propene-d6 (CD2=CDCD3) have been investigated, employing gas chromatography, mass spectroscopy, and flame ionization (GC/MS/FID) detection methods. The yields of methane as well as butadiene relative to ethane show considerable variations when propene-h6 or propene-d6 are photolyzed. This suggests significant variances in the relative importance of primary photolytic processes and/or secondary radical reactions, occurring subsequent to the photolysis. Theoretical calculations suggest the potential occurrence of an intramolecular dissociation through a mechanism involving vinylidene formation, accompanied by an ethylenic H-migration through the pi-orbitals. This process affects the final yields of methane-h4 versus methane-d4 with respect to other products. The product yields from previous studies of the 193 nm photolysis of methyl vinyl ketone-h6 and -d6 (CH2=CHCOCH3, CD2=CDCOCD3), alternative precursors for generating methyl and vinyl radicals, are compared with the current results for propene.

  3. Assessing the Efficacy of the Aerobic Methanotrophic Biofilter in Methane Hydrate Environments

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

    Valentine, David

    2012-09-30

    In October 2008 the University of California at Santa Barbara (UCSB) initiated investigations of water column methane oxidation in methane hydrate environments, through a project funded by the National Energy Technology Laboratory (NETL) entitled: assessing the efficacy of the aerobic methanotrophic biofilter in methane hydrate environments. This Final Report describes the scientific advances and discoveries made under this award as well as the importance of these discoveries in the broader context of the research area. Benthic microbial mats inhabit the sea floor in areas where reduced chemicals such as sulfide reach the more oxidizing water that overlies the sediment. Wemore » set out to investigate the role that methanotrophs play in such mats at locations where methane reaches the sea floor along with sulfide. Mats were sampled from several seep environments and multiple sets were grown in-situ at a hydrocarbon seep in the Santa Barbara Basin. Mats grown in-situ were returned to the laboratory and used to perform stable isotope probing experiments in which they were treated with 13C-enriched methane. The microbial community was analyzed, demonstrating that three or more microbial groups became enriched in methane?s carbon: methanotrophs that presumably utilize methane directly, methylotrophs that presumably consume methanol excreted by the methanotrophs, and sulfide oxidizers that presumably consume carbon dioxide released by the methanotrophs and methylotrophs. Methanotrophs reached high relative abundance in mats grown on methane, but other bacterial processes include sulfide oxidation appeared to dominate mats, indicating that methanotrophy is not a dominant process in sustaining these benthic mats, but rather a secondary function modulated by methane availability. Methane that escapes the sediment in the deep ocean typically dissolved into the overlying water where it is available to methanotrophic bacteria. We set out to better understand the efficacy of this process as a biofilter by studying the distribution of methane oxidation and disposition of methanotrophic populations in the Pacific Ocean. We investigated several environments including the basins offshore California, the continental margin off Central America, and the shallow waters around gas seeps. We succeeded in identifying the distributions of activity in these environments, identified potential physical and chemical controls on methanotrophic activity, we further revealed details about the methanotrophic communities active in these settings, and we developed new approaches to study methanotrophic communities. These findings should improve our capacity to predict the methanotrophic response in ocean waters, and further our ability to generate specific hypotheses as to the ecology and efficacy of pelagic methanotrophic communites. The discharge of methane and other hydrocarbons to Gulf of Mexico that followed the sinking of the Deepwater Horizon provided a unique opportunity to study the methanotorphic biofilter in the deep ocean environment. We set out to understand the consumption of methane and the bloom of methanotrophs resulting from this event, as a window into the regional scale release of gas hydrate under rapid warming scenarios. We found that other hydrocarbon gases, notably propane and ethane, were preferred for consumption over methane, but that methane consumption accelerated rapidly and drove the depletion of methane within a matter of months after initial release. These results revealed the identity of the responsible community, and point to the importance of the seed population in determining the rate at which a methanotrophic community is able to respond to an input of methane. Collectively, these results provide a significant advance in our understanding of the marine methanotrohic biofilter, and further provide direction and context for future investigations of this important phenomenon. This project has resulted in fourteen publications to date, with five more circulating in draft form, and several others planned.« less

  4. Liquid Hydrocarbons on Titan's Surface? How Cassini ISS Observations Fit into the Story (So Far)

    NASA Technical Reports Server (NTRS)

    Turtle, E. P.; Dawson, D. D.; Fussner, S.; Hardegree-Ullman, E.; Ewen, A. S.; Perry, J.; Porco, C. C.; West, R. A.

    2005-01-01

    Titan is the only satellite in our Solar System with a substantial atmosphere, the origins and evolution of which are still not well understood. Its primary (greater than 90%) component is nitrogen, with a few percent methane and lesser amounts of other species. Methane and ethane are stable in the liquid state under the temperature and pressure conditions in Titan s lower atmosphere and at the surface; indeed, clouds, likely composed of methane, have been detected. Photochemical processes acting in the atmosphere convert methane into more complex hydrocarbons, creating Titan s haze and destroying methane over relatively short timescales. Therefore, it has been hypothesized that Titan s surface has reservoirs of liquid methane which serve to resupply the atmosphere. Early observations of Titan s surface revealed albedo patterns which have been interpreted as dark hydrocarbon liquids occupying topographically low regions between higher-standing exposures of bright, water-ice bedrock, although this is far from being the only explanation for the observed albedo contrast. Observations made by the Imaging Science Subsystem during Cassini's approach to Saturn and its first encounters with Titan show the bright and dark regions in greater detail but have yet to resolve the question of whether there are liquids on the surface.

  5. The key nickel enzyme of methanogenesis catalyses the anaerobic oxidation of methane.

    PubMed

    Scheller, Silvan; Goenrich, Meike; Boecher, Reinhard; Thauer, Rudolf K; Jaun, Bernhard

    2010-06-03

    Large amounts (estimates range from 70 Tg per year to 300 Tg per year) of the potent greenhouse gas methane are oxidized to carbon dioxide in marine sediments by communities of methanotrophic archaea and sulphate-reducing bacteria, and thus are prevented from escaping into the atmosphere. Indirect evidence indicates that the anaerobic oxidation of methane might proceed as the reverse of archaeal methanogenesis from carbon dioxide with the nickel-containing methyl-coenzyme M reductase (MCR) as the methane-activating enzyme. However, experiments showing that MCR can catalyse the endergonic back reaction have been lacking. Here we report that purified MCR from Methanothermobacter marburgensis converts methane into methyl-coenzyme M under equilibrium conditions with apparent V(max) (maximum rate) and K(m) (Michaelis constant) values consistent with the observed in vivo kinetics of the anaerobic oxidation of methane with sulphate. This result supports the hypothesis of 'reverse methanogenesis' and is paramount to understanding the still-unknown mechanism of the last step of methanogenesis. The ability of MCR to cleave the particularly strong C-H bond of methane without the involvement of highly reactive oxygen-derived intermediates is directly relevant to catalytic C-H activation, currently an area of great interest in chemistry.

  6. Methane and carbon dioxide fluxes in the waterlogged forests of south and middle taiga of Western Siberia

    NASA Astrophysics Data System (ADS)

    Glagolev, M. V.; Ilyasov, D. V.; Terentieva, I. E.; Sabrekov, A. F.; Mochenov, S. Yu; Maksutov, S. S.

    2018-03-01

    Field measurements of methane and carbon dioxide flux were carried out using portable static chambers in south (ST) and middle taiga subzones (MT) of Western Siberia (WS) from 16 to 24 August 2015. Two sites were investigated: Bakchar bog in the Tomsk region (in typical ecosystems for this area: oligotrophic bog/forest border and waterlogged forest) and Shapsha in Khanty-Mansiysk region (in waterlogged forest). The highest values of methane fluxes (mgC·m-2·h-1) were obtained in burnt wet birch forest (median 6.96; first quartile 3.12; third quartile 8.95). The lowest values of methane fluxes (among the sites mentioned above) were obtained in seasonally waterlogged forests (median -0.08; first and third quartiles are -0.14 and -0.03 mgC·m-2·h-1 respectively). These data will help to estimate the regional methane flux from the waterlogged and periodically flooded forests and to improve its prediction.

  7. Heterogeneous Photocatalytic Oxidation of Atmospheric Trace Contaminants

    NASA Technical Reports Server (NTRS)

    Ollis, David F.

    1996-01-01

    Heterogeneous photocatalysis involves the use of a light-activated catalyst at room temperature in order to carry out a desired reaction. In the presence of molecular oxygen, illumination of the n-type semiconductor oxide titanium dioxide (TiO2) provides for production of highly active forms of oxygen, such as hydroxyl radicals, which are able to carry out the complete oxidative destruction of simple hydrocarbons such as methane, ethane, ethylene, propylene, and carbon monoxide. This broad oxidation potential, coupled with the ability with sufficient residence time to achieve complete oxidation of simple hydrocarbon contaminants to carbon dioxide and water, indicated that heterogeneous photocatalysis should be examined for its potential for purification of spacecraft air. If a successful catalyst and photoreactor could be demonstrated at the laboratory level, such results would allow consideration of photocatalysts as a partial or complete replacement of adsorption systems, thereby allowing for reduction in lift-off weight of a portion of the life support system for the spacecraft, or other related application such as a space station or a conventional commercial aircraft. The present research was undertaken to explore this potential through achievement of the following plan of work: (a) ascertain the intrinsic kinetics of conversion of pollutants of interest in spacecraft, (b) ascertain the expected lifetime of catalysts through examination of most likely routes of catalyst deactivation and regeneration, (c) model and explore experimentally the low pressure drop catalytic monolith, a commercial configuration for automotive exhaust control, and (d) examine the kinetics of multicomponent conversions. In the recent course of this work, we have also discovered how to increase catalyst activity via halide promotion which has allowed us to achieve approximately 100% conversion of an aromatic contaminant (toluene) in a very short residence time of 5-6 milliseconds.

  8. Heterogeneous Photocatalytic Oxidation of Atmospheric Trace Contaminants

    NASA Technical Reports Server (NTRS)

    Ollis, David F.

    1996-01-01

    Heterogeneous photocatalysis involves the use of a light-activated catalyst at room temperature in order to carry out a desired reaction. In the presence of molecular oxygen, illumination of the n-type semiconductor oxide titanium dioxide (TiO2) provides for production of highly active forms of oxygen, such as hydroxyl radicals, which are able to carry out the complete oxidative destruction of simple hydrocarbons such as methane, ethane, ethylene, propylene, and carbon monoxide. This broad oxidation potential, coupled with the ability with sufficient residence time to achieve complete oxidation of simple hydrocarbon contaminants to carbon dioxide and water, indicated that heterogeneous photocatalysis should be examined for its potential for purification of spacecraft air. If a successful catalyst and photoreactor could be demonstrated at the laboratory level, such results would allow consideration of photocatalysts as a partial or complete replacement of adsorption systems, thereby allowing for reduction in lift-off weight of a portion of the life support system for the spacecraft, or other related application such as a space station or a conventional commercial aircraft. The present research was undertaken to explore this potential through achievement of the following plan of work: (a) ascertain the intrinsic kinetics of conversion of pollutants of interest in spacecraft, (b) ascertain the expected lifetime of catalysts through examination of most likely routes of catalyst deactivation and regeneration (c) model and explore experimentally the low pressure drop catalytic monolith, a commercial configuration for automotive exhaust control (d) examine the kinetics of multicomponent conversions. In the recent course of this work, we have also discovered how to increase catalyst activity via halide promotion which has allowed us to achieve approximately 100% conversion of an aromatic contaminant (toluene) in a very short residence time of 5-6 milliseconds.

  9. On the sources of methane to the Los Angeles atmosphere.

    PubMed

    Wennberg, Paul O; Mui, Wilton; Wunch, Debra; Kort, Eric A; Blake, Donald R; Atlas, Elliot L; Santoni, Gregory W; Wofsy, Steven C; Diskin, Glenn S; Jeong, Seongeun; Fischer, Marc L

    2012-09-04

    We use historical and new atmospheric trace gas observations to refine the estimated source of methane (CH(4)) emitted into California's South Coast Air Basin (the larger Los Angeles metropolitan region). Referenced to the California Air Resources Board (CARB) CO emissions inventory, total CH(4) emissions are 0.44 ± 0.15 Tg each year. To investigate the possible contribution of fossil fuel emissions, we use ambient air observations of methane (CH(4)), ethane (C(2)H(6)), and carbon monoxide (CO), together with measured C(2)H(6) to CH(4) enhancement ratios in the Los Angeles natural gas supply. The observed atmospheric C(2)H(6) to CH(4) ratio during the ARCTAS (2008) and CalNex (2010) aircraft campaigns is similar to the ratio of these gases in the natural gas supplied to the basin during both these campaigns. Thus, at the upper limit (assuming that the only major source of atmospheric C(2)H(6) is fugitive emissions from the natural gas infrastructure) these data are consistent with the attribution of most (0.39 ± 0.15 Tg yr(-1)) of the excess CH(4) in the basin to uncombusted losses from the natural gas system (approximately 2.5-6% of natural gas delivered to basin customers). However, there are other sources of C(2)H(6) in the region. In particular, emissions of C(2)H(6) (and CH(4)) from natural gas seeps as well as those associated with petroleum production, both of which are poorly known, will reduce the inferred contribution of the natural gas infrastructure to the total CH(4) emissions, potentially significantly. This study highlights both the value and challenges associated with the use of ethane as a tracer for fugitive emissions from the natural gas production and distribution system.

  10. Emissions due to the natural gas storage well-casing blowout at Aliso Canyon/SS-25

    NASA Astrophysics Data System (ADS)

    Herndon, Scott; Daube, Conner; Jervis, Dylan; Yacovitch, Tara; Roscioli, Joseph; Curry, Jason; Nelson, David; Knighton, Berk

    2017-04-01

    The pronounced increase in unconventional gas production in North America over the last fifteen years has intensified interest in understanding emissions and leaks in the supply chain from well pad to end use. Los Angeles, California is home 19 million consumers of natural gas in both industry and domestic end use. The well blowout at Aliso Canyon Natural Gas Storage Facility in the greater Los Angeles area was quantified using the tracer flux ratio method (TFR). Over 400 tracer plume transects were collected, each lasting 15-300 seconds, using instrumentation aboard a mobile platform on 25 days between December 21, 2015 and March 9, 2016. The leak rate from October 23rd to February 11th has been estimated here using a combination of this work (TFR) and the flight mass balance (FMB) data [Conley et al., 2016]. This estimate relies on the TFR data as the most specific SS-25 emission dataset. Scaling the FMB dataset, the leak rate is projected from Oct 23rd to December 21th. Adding up the emissions inferred and measured suggests a total leak burden of 86,022 ± 8,393 metric tons of methane. This work quantified the emissions during the "bottom kill" procedure which halted the primary emission leak. The ethane to methane enhancement ratio observed downwind of the leak site is consistent with the content of ethane in the natural gas at this site and provides definitive evidence that the methane emission rate quantified via tracer flux ratio is not due to a nearby landfill or other potential biogenic sources. Additionally, the TFR approach employed here is assessing only the leaks due to the SS-25 well blowout and excludes other possible emissions at the facility.

  11. Jupiter's Polar Haze

    NASA Astrophysics Data System (ADS)

    Carlson, B. E.

    1997-07-01

    The nature and distribution of stratospheric aerosols in the polar regions of Jupiter are investigated using a combination of ground-based, Hubble Space Telescope (HST), and Voyager IRIS measurements. Of particular interest are the connections between the enhanced UV absorption in the polar regions and the bright polar hoods evident in methane band images and the connections between the aerosol, the infrared "hot spot", and the auroras. Spatial maps of the hydrocarbon emissions constructed from the Voyager IRIS measurements reveal enhanced acetylene emission coincident with the region of enhanced methane emission but morphologically distinct from the region of enhanced ethane emission. This finding confirms the existence of altitude- dependent hydrocarbon chemistry. Ground-based and HST data reveal the presence of longitudinal structure in the latitudinal distribution of the aerosols (i.e., break-down in zonal symmetry) apparently associated with circulation anomalies induced by the polar hot spot. In addition, the HST data reveal a change in the aerosol properties (e.g., phase function) in the vicinity of the hot spot while ruling out changes in their height and/or optical depth distribution. The HST data also reveal differential UV absorption coincident with the aurora strengthening the connection between aerosol formation/hydrocarbon chemistry and the aurora. The spectral dependence of this absorption suggests enhancements of the higher order hydrocarbons (e.g., benzene). The mismatch in spatial resolution between infrared (Voyager IRIS/ground-based IRTF) and HST measurements coupled with the change in morphology of the hot spot as revealed by the structure of the methane/acetylene emission versus that of the ethane emission suggests the existence of more complex spatial structure and additional thermal emission anomalies associated with auroral processes unresolved by current infrared measurements

  12. Titan as the Abode of Life

    NASA Technical Reports Server (NTRS)

    Mckay, Christopher P.

    2016-01-01

    Titan is the only world we know other than Earth that has a liquid on its surface. It has a thick atmosphere composed of nitrogen and methane with a thick organic haze. There are lakes, rain, and clouds of methane and ethane. Here, we address the question of carbon-based life living in Titan liquids. Photochemically produced organics, particularly acetylene, in Titan's atmosphere could be a source of biological energy when reacted with atmospheric hydrogen. Light levels on the surface of Titan are more than adequate for photosynthesis but the biochemical limitations due to the few elements available in the environment may lead only to simple ecosystems that only consume atmospheric nutrients. Life on Titan may make use of the trace metals and other inorganic elements produced by meteorites as they ablate in the atmosphere. It is conceivable that H2O molecules on Titan could be used in a biochemistry that is rooted in hydrogen bonds in a way that metals are used in enzymes by life on Earth. Previous theoretical work has shown possible membrane structures in Titan liquids, azotosomes, composed of small organic nitrogen compounds, such as acrylonitrile. The search for a plausible information molecule for life in Titan liquids remains an open research topic - polyethers have been considered and shown to be insoluble at Titan temperatures. Possible search strategies for life on Titan include looking for unusual concentrations of certain molecules reflecting biological selection. Homochirality is a special and powerful example of such biology selection. Environmentally, a depletion of hydrogen in the lower atmosphere may be a sign of metabolism. A discovery of life in liquid methane and ethane would be our first compelling indication that the Universe is full of diverse and wondrous life forms.

  13. On the Sources of Methane to the Los Angeles Atmosphere

    NASA Technical Reports Server (NTRS)

    Wennberg, Paul O.; Mui, Wilton; Fischer, Marc L.; Wunch, Debra; Kort, Eric A.; Blake, Donald R.; Atlas, Elliot L.; Santoni, Gregory W.; Wofsy, Steven C.; Diskin, Glenn S.; hide

    2012-01-01

    We use historical and new atmospheric trace gas observations to refine the estimated source of methane (CH4) emitted into California's South Coast Air Basin (the larger Los Angeles metropolitan region). Referenced to the California Air Resources Board (CARB) CO emissions inventory, total CH4 emissions are 0.44 +/- 0.15 Tg each year. To investigate the possible contribution of fossil fuel emissions, we use ambient air observations of methane (CH4), ethane (C2H6), and carbon monoxide (CO), together with measured C2H6 to CH4 enhancement ratios in the Los Angeles natural gas supply. The observed atmospheric C2H6 to CH4 ratio during the ARCTAS (2008) and CalNex (2010) aircraft campaigns is similar to the ratio of these gases in the natural gas supplied to the basin during both these campaigns. Thus, at the upper limit (assuming that the only major source of atmospheric C2H6 is fugitive emissions from the natural gas infrastructure) these data are consistent with the attribution of most (0.39 +/- 0.15 Tg yr-1) of the excess CH4 in the basin to uncombusted losses from the natural gas system (approximately 2.5-6% of natural gas delivered to basin customers). However, there are other sources of C2H6 in the region. In particular, emissions of C2H6 (and CH4) from natural gas seeps as well as those associated with petroleum production, both of which are poorly known, will reduce the inferred contribution of the natural gas infrastructure to the total CH4 emissions, potentially significantly. This study highlights both the value and challenges associated with the use of ethane as a tracer for fugitive emissions from the natural gas production and distribution system.

  14. Titan as the Abode of Life

    NASA Astrophysics Data System (ADS)

    McKay, Christopher P.

    2016-02-01

    Titan is the only world we know, other than Earth, that has a liquid on its surface. It also has a thick atmosphere composed of nitrogen and methane with a thick organic haze. There are lakes, rain, and clouds of methane and ethane. Here, we address the question of carbon-based life living in Titan liquids. Photochemically produced organics, particularly acetylene, in Titan's atmosphere could be a source of biological energy when reacted with atmospheric hydrogen. Light levels on the surface of Titan are more than adequate for photosynthesis, but the biochemical limitations due to the few elements available in the environment may lead only to simple ecosystems that only consume atmospheric nutrients. Life on Titan may make use of the trace metals and other inorganic elements produced by meteorites as they ablate in its atmosphere. It is conceivable that H2O molecules on Titan could be used in a biochemistry that is rooted in hydrogen bonds in a way that metals are used in enzymes by life on Earth. Previous theoretical work has shown possible membrane structures, azotosomes, in Titan liquids, azotosomes, composed of small organic nitrogen compounds, such as acrylonitrile. The search for a plausible information molecule for life in Titan liquids remains an open research topic - polyethers have been considered and shown to be insoluble at Titan temperatures. Possible search strategies for life on Titan include looking for unusual concentrations of certain molecules reflecting biological selection. Homochirality is a special and powerful example of such biology selection. Environmentally, a depletion of hydrogen in the lower atmosphere may be a sign of metabolism. A discovery of life in liquid methane and ethane would be our first compelling indication that the universe is full of diverse and wondrous life forms.

  15. Titan as the Abode of Life.

    PubMed

    McKay, Christopher P

    2016-02-03

    Titan is the only world we know, other than Earth, that has a liquid on its surface. It also has a thick atmosphere composed of nitrogen and methane with a thick organic haze. There are lakes, rain, and clouds of methane and ethane. Here, we address the question of carbon-based life living in Titan liquids. Photochemically produced organics, particularly acetylene, in Titan's atmosphere could be a source of biological energy when reacted with atmospheric hydrogen. Light levels on the surface of Titan are more than adequate for photosynthesis, but the biochemical limitations due to the few elements available in the environment may lead only to simple ecosystems that only consume atmospheric nutrients. Life on Titan may make use of the trace metals and other inorganic elements produced by meteorites as they ablate in its atmosphere. It is conceivable that H₂O molecules on Titan could be used in a biochemistry that is rooted in hydrogen bonds in a way that metals are used in enzymes by life on Earth. Previous theoretical work has shown possible membrane structures, azotosomes, in Titan liquids, azotosomes, composed of small organic nitrogen compounds, such as acrylonitrile. The search for a plausible information molecule for life in Titan liquids remains an open research topic-polyethers have been considered and shown to be insoluble at Titan temperatures. Possible search strategies for life on Titan include looking for unusual concentrations of certain molecules reflecting biological selection. Homochirality is a special and powerful example of such biology selection. Environmentally, a depletion of hydrogen in the lower atmosphere may be a sign of metabolism. A discovery of life in liquid methane and ethane would be our first compelling indication that the universe is full of diverse and wondrous life forms.

  16. Quantification of Methane and Ethane Emissions from the San Juan Basin

    NASA Astrophysics Data System (ADS)

    Smith, M. L.; Kort, E. A.; Karion, A.; Sweeney, C.; Gvakharia, A.

    2015-12-01

    Methane (CH4), a potent greenhouse gas, and the primary component of natural gas, is emitted from areas of high fossil fuel production and processing. Recently, persistent and large methane emissions (~0.59 Tg yr-1) from the four corners area of the United States have been identified using satellite (SCIAMACHY) observations taken over the years 2003 to 2009. These emissions appear to be the largest CH4 anomaly (positive deviation above background values) in the contiguous U.S., and exceed bottom-up inventory estimates for the area by 1.8 to 3.5 times. The majority of emissions sources expected to contribute to this anomalous CH4 signal are located in the San Juan basin of New Mexico, and include harvesting and processing of natural gas, coal, and coalbed CH4. The magnitude of CH4 emissions from the San Juan basin have not yet been directly quantified using airborne measurements. Additionally, changing fossil fuel-related activities in the basin may have altered the magnitude of CH4 emissions compared to estimates derived from 2003-2009 satellite measurements. Here, we present in-situ airborne observations of CH4 over the San Juan basin, which allow tight quantification of CH4 fluxes using the mass balance method. Observations over the basin were taken for multiple wind directions on multiple days in April, 2015 to obtain a robust estimate of CH4 emissions. The flux of ethane (C2H6), the second most abundant component of natural gas and a tracer species indicative of fossil-derived CH4, was also quantified. Substantial C2H6 emissions may affect regional air quality and chemistry through its influence on tropospheric ozone production.

  17. Titan as the Abode of Life

    PubMed Central

    McKay, Christopher P.

    2016-01-01

    Titan is the only world we know, other than Earth, that has a liquid on its surface. It also has a thick atmosphere composed of nitrogen and methane with a thick organic haze. There are lakes, rain, and clouds of methane and ethane. Here, we address the question of carbon-based life living in Titan liquids. Photochemically produced organics, particularly acetylene, in Titan’s atmosphere could be a source of biological energy when reacted with atmospheric hydrogen. Light levels on the surface of Titan are more than adequate for photosynthesis, but the biochemical limitations due to the few elements available in the environment may lead only to simple ecosystems that only consume atmospheric nutrients. Life on Titan may make use of the trace metals and other inorganic elements produced by meteorites as they ablate in its atmosphere. It is conceivable that H2O molecules on Titan could be used in a biochemistry that is rooted in hydrogen bonds in a way that metals are used in enzymes by life on Earth. Previous theoretical work has shown possible membrane structures, azotosomes, in Titan liquids, azotosomes, composed of small organic nitrogen compounds, such as acrylonitrile. The search for a plausible information molecule for life in Titan liquids remains an open research topic—polyethers have been considered and shown to be insoluble at Titan temperatures. Possible search strategies for life on Titan include looking for unusual concentrations of certain molecules reflecting biological selection. Homochirality is a special and powerful example of such biology selection. Environmentally, a depletion of hydrogen in the lower atmosphere may be a sign of metabolism. A discovery of life in liquid methane and ethane would be our first compelling indication that the universe is full of diverse and wondrous life forms. PMID:26848689

  18. Local- and regional-scale measurements of CH4, δ13CH4, and C2H6 in the Uintah Basin using a mobile stable isotope analyzer

    NASA Astrophysics Data System (ADS)

    Rella, C. W.; Hoffnagle, J.; He, Y.; Tajima, S.

    2015-10-01

    In this paper, we present an innovative CH4, δ13CH4, and C2H6 instrument based on cavity ring-down spectroscopy (CRDS). The design and performance of the analyzer is presented in detail. The instrument is capable of precision of less than 1 ‰ on δ13CH4 with 1 in. of averaging and about 0.1 ‰ in an hour. Using this instrument, we present a comprehensive approach to atmospheric methane emissions attribution. Field measurements were performed in the Uintah Basin (Utah, USA) in the winter of 2013, using a mobile lab equipped with the CRDS analyzer, a high-accuracy GPS, a sonic anemometer, and an onboard gas storage and playback system. With a small population and almost no other sources of methane and ethane other than oil and gas extraction activities, the Uintah Basin represents an ideal location to investigate and validate new measurement methods of atmospheric methane and ethane. We present the results of measurements of the individual fugitive emissions from 23 natural gas wells and six oil wells in the region. The δ13CH4 and C2H6 signatures that we observe are consistent with the signatures of the gases found in the wells. Furthermore, regional measurements of the atmospheric CH4, δ13CH4, and C2H6 signatures throughout the basin have been made, using continuous sampling into a 450 m long tube and laboratory reanalysis with the CRDS instrument. These measurements suggest that 85 ± 7 % of the total emissions in the basin are from natural gas production.

  19. Adsorption and Gas Separation of Molecules by Carbon Nanohorns.

    PubMed

    Gatica, Silvina M; Nekhai, Anton; Scrivener, Adam

    2016-05-19

    In this paper, we report the results of Monte Carlo simulations of the adsorption of neon, argon, methane and carbon dioxide in carbon nanohorns. We model the nanohorns as an array of carbon cones and obtained adsorption isotherms and isosteric heats. The main sites of adsorption are inside the cones and in the interstices between three cones. We also calculated the selectivity of carbon dioxide/methane, finding that nanohorns are a suitable substrate for gas separation. Our simulations are compared to available experimental data.

  20. Biogas reforming over multi walled carbon nanotubes with Co-Mo/MgO nanoparticles

    NASA Astrophysics Data System (ADS)

    Khavarian, Mehrnoush; Mohamed, Abdul Rahman

    2017-12-01

    The utilization of biogas for the production of valuable chemicals is among the very important processes in the energy research field. The most suitable process for biogas reforming is dry reforming of methane. An obvious drawback is the variable composition of biogas rather than the stoichiometrically equimolar quantities of methane and carbon dioxide. Moreover, activating the methane and carbon dioxide molecules in the reforming reaction provides many challenges in exploring new concepts and opportunities for development of unique catalysts. In the present work, the catalytic activity behavior of Co-Mo-MgO/multi-walled carbon nanotubes (MWCNTs) nanocomposite in dry reforming was investigated with different CO2/CH4 feed ratio to evaluate the performance of this catalyst for biogas reforming reaction. It was found that conversions of methane and carbon dioxide were greatly influenced by the feed gas ratio. The CH4 and CO2 conversions are 83 % and 87 % at the reaction temperature of 825 °C, GHSV of 175 L/h.gcat and CO2/CH4 feed ratio of unity. The minimum carbon deposition rate is observed at the CO2/CH4 feed ratio of 0.6 which is 0.080 gc/gcat-h.

  1. State Air Quality Standards.

    ERIC Educational Resources Information Center

    Pollution Engineering, 1978

    1978-01-01

    This article presents in tabular form the air quality standards for sulfur dioxide, carbon monoxide, nitrogen dioxide, photochemicals, non-methane hydrocarbons and particulates for each of the 50 states and the District of Columbia. (CS)

  2. Quantification of Methane Leaks from Abandoned Oil and Gas Wells in California

    NASA Astrophysics Data System (ADS)

    Lebel, E.; Kang, M.; Lu, H.; Jackson, R. B.

    2016-12-01

    Abandoned oil and gas wells can provide a pathway for subterranean methane and other gases to be emitted to the atmosphere. However, abandoned wells are unaccounted for in greenhouse gas emissions inventories. While relatively little is known about abandoned wells, previous studies have shown that emissions from abandoned wells contribute approximately 4-7% of anthropogenic methane emissions in Pennsylvania (Kang et al. 2014) and <1% of regional methane emissions in oil and gas producing regions of Colorado, Utah, Ohio, and Wyoming (Townsend-Small et al. 2015). Another study (Boothroyd et al. 2016) has shown that 30% of abandoned wells in the UK have a positive surface methane flux. California has a long history of oil and gas production, beginning from the 1860s, and currently ranks third in oil production by state. As a result, there are more than 100,000 wells across the state. Our study uses static flux chambers to measure individual abandoned wells in California to estimate state-wide methane emissions from these wells. In addition to measuring methane concentrations, we measure ethane, propane, isobutane, n-butane, and 13-CH4 to understand whether this methane has a biogenic or thermogenic source. We hope that our research will determine whether or not abandoned oil and gas wells are a significant source of anthropogenic methane emissions in California. Our results along with measurements in other parts of the United States can be used to scale up methane emission estimates to the national level, accounting for the millions of abandoned wells in the country.

  3. Methane as a product of chloroethene biodegradation under methanogenic conditions

    USGS Publications Warehouse

    Bradley, P.M.; Chapelle, F.H.

    1999-01-01

    Radiometric detection headspace analyses of microcosms containing bed sediments from two geographically distinct sites indicated that 10-39% of the radiolabeled carbon transformed during anaerobic biodegradation of [1,2- 14C]trichloroethene (TCE) or [1,2-14C]vinyl chloride (VC) under methanogenic conditions was ultimately incorporated into 14CH4. The results demonstrate that, in addition to ethene, ethane, and CO2, CH4 can be a significant product of chloroethene biodegradation in some methanogenic sediments.Radiometric detection headspace analyses of microcosms containing bed sediments from two geographically distinct sites indicated that 10-39% of the radiolabeled carbon transformed during anaerobic biodegradation of [1,2-14C]trichloroethene (TCE) or [1,2-14C]vinyl chloride (VC) under methanogenic conditions was ultimately incorporated into 14CH4. The results demonstrate that, in addition to ethene, ethane, and CO2, CH4 can be a significant product of chloroethene biodegradation in some methanogenic sediments.

  4. Plasma Methane Pyrolysis for Spacecraft Oxygen Loop Closure

    NASA Technical Reports Server (NTRS)

    Greenwood, Z. W.

    2018-01-01

    Life support is a critical function of any crewed space vehicle or habitat. Human life support systems on the International Space Station (ISS) include a number of atmosphere revitalization (AR) technologies to provide breathable air and a comfortable living environment to the crew. The Trace Contaminant Control System removes harmful volatile organic compounds and other trace contaminants from the circulating air. The Carbon Dioxide Removal Assembly (CDRA) removes metabolic carbon dioxide (CO2) and returns air to the cabin. Humidity is kept at comfortable levels by a number of condensing heat exchangers. The Oxygen Generation Assembly (OGA) electrolyzes water to produce oxygen for the crew and hydrogen (H2) as a byproduct. A Sabatier reaction-based CO2 Reduction Assembly (CRA) was launched to the ISS in 2009 and became fully operational in June 2011.The CRA interfaces with both the OGA and CDRA. Carbon dioxide from the CDRA is compressed and stored in tanks until hydrogen is available from OGA water electrolysis. When the OGA is operational and there is CO2 available, the CRA is activated and produces methane and water via the Sabatier reaction shown in Equation 1... One approach to achieve these higher recovery rates builds upon the ISS AR architecture and includes adding a methane post-processor to recover H2 from CRA methane. NASA has been developing the Plasma Pyrolysis Assembly (PPA) to fill the role of a methane post-processor.

  5. Characterizing Dissolved Gases in Cryogenic Liquid Fuels

    NASA Astrophysics Data System (ADS)

    Richardson, Ian A.

    Pressure-Density-Temperature-Composition (PrhoT-x) measurements of cryogenic fuel mixtures are a historical challenge due to the difficulties of maintaining cryogenic temperatures and precision isolation of a mixture sample. For decades NASA has used helium to pressurize liquid hydrogen propellant tanks to maintain tank pressure and reduce boil off. This process causes helium gas to dissolve into liquid hydrogen creating a cryogenic mixture with thermodynamic properties that vary from pure liquid hydrogen. This can lead to inefficiencies in fuel storage and instabilities in fluid flow. As NASA plans for longer missions to Mars and beyond, small inefficiencies such as dissolved helium in liquid propellant become significant. Traditional NASA models are unable to account for dissolved helium due to a lack of fundamental property measurements necessary for the development of a mixture Equation Of State (EOS). The first PrhoT-x measurements of helium-hydrogen mixtures using a retrofitted single-sinker densimeter, magnetic suspension microbalance, and calibrated gas chromatograph are presented in this research. These measurements were used to develop the first multi-phase EOS for helium-hydrogen mixtures which was implemented into NASA's Generalized Fluid System Simulation Program (GFSSP) to determine the significance of mixture non-idealities. It was revealed that having dissolved helium in the propellant does not have a significant effect on the tank pressurization rate but does affect the rate at which the propellant temperature rises. PrhoT-x measurements are conducted on methane-ethane mixtures with dissolved nitrogen gas to simulate the conditions of the hydrocarbon seas of Saturn's moon Titan. Titan is the only known celestial body in the solar system besides Earth with stable liquid seas accessible on the surface. The PrhoT-x measurements are used to develop solubility models to aid in the design of the Titan Submarine. NASA is currently designing the submarine to explore the depths of Titan's methane-ethane seas to study the evolution of hydrocarbons in the universe and provide a pathfinder for future submersible designs. In addition, effervescence and freezing liquid line measurements on various liquid methane-ethane compositions with dissolved gaseous nitrogen are presented from 1.5 bar to 4.5 bar and temperatures from 92 K to 96 K to improve simulations of the conditions of the seas. These measurements will be used to validate sea property and bubble incipience models for the Titan Submarine design.

  6. Distribution of gases in the unsaturated zone at a low-level radioactive-waste disposal site near Sheffield, Illinois

    USGS Publications Warehouse

    Striegl, Robert G.

    1988-01-01

    The unsaturated zone is a medium that provides pneumatic communication for the movement of gases from wastes buried in landfills to the atmosphere, biota, and groundwater. Gases in unsaturated glacial and eolian deposits near a waste-disposal trench at the low-level radioactive-waste disposal site near Sheffield, Bureau County, Illinois, were identified, and the spatial and temporal distributions of the partial pressures of those gases were determined for the period January 1984 through January 1986. Methods for the collection and analyses of the gases are described, as are geologic and hydrologic characteristics of the unsaturated zone that affect gas transport. The identified gases, which are of natural and of waste origin, include nitrogen, oxygen, and argon, carbon dioxide, methane, propane, butane, tritiated water vapor, 14carbon dioxide, and 222 radon. Concentrations of methane and 14carbon dioxide originated at the waste, as shown by partial-pressure gradients of the gases; 14carbon dioxide partial pressures exceeded natural background partial pressures by factors greater than 1 million at some locations. Variations in partial pressures of oxygen and carbon dioxide were seasonal among piezometers because of increased root and soil-microbe respiration during summer. Variations in methane and 14carbon dioxide partial pressures were apparently related to discrete releases from waste sources at unpredictable intervals of time. No greater than background partial pressures for tritiated water vapor or 222 radon were measured. (USGS)

  7. Molecular simulation of gas adsorption and diffusion in a breathing MOF using a rigid force field.

    PubMed

    García-Pérez, E; Serra-Crespo, P; Hamad, S; Kapteijn, F; Gascon, J

    2014-08-14

    Simulation of gas adsorption in flexible porous materials is still limited by the slow progress in the development of flexible force fields. Moreover, the high computational cost of such flexible force fields may be a drawback even when they are fully developed. In this work, molecular simulations of gas adsorption and diffusion of carbon dioxide and methane in NH2-MIL-53(Al) are carried out using a linear combination of two crystallographic structures with rigid force fields. Once the interactions of carbon dioxide molecules and the bridging hydroxyls groups of the framework are optimized, an excellent match is found for simulations and experimental data for the adsorption of methane and carbon dioxide, including the stepwise uptake due to the breathing effect. In addition, diffusivities of pure components are calculated. The pore expansion by the breathing effect influences the self-diffusion mechanism and much higher diffusivities are observed at relatively high adsorbate loadings. This work demonstrates that using a rigid force field combined with a minimum number of experiments, reproduces adsorption and simulates diffusion of carbon dioxide and methane in the flexible metal-organic framework NH2-MIL-53(Al).

  8. 76 FR 80928 - Agency Information Collection Activities; Submission to OMB for Review and Approval; Comment...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-12-27

    ... operation and maintenance of this equipment. These standards rely on the capture and reduction of methane, carbon dioxide, and non-methane organic gas compound emissions by combustion devices (boilers, internal...

  9. Permafrost slowly exhales methane

    NASA Astrophysics Data System (ADS)

    Herndon, Elizabeth M.

    2018-04-01

    Permafrost soils store vast quantities of organic matter that are vulnerable to decomposition under a warming climate. Recent research finds that methane release from thawing permafrost may outpace carbon dioxide as a major contributor to global warming over the next century.

  10. Reconciling divergent estimates of oil and gas methane emissions

    PubMed Central

    Zavala-Araiza, Daniel; Lyon, David R.; Alvarez, Ramón A.; Davis, Kenneth J.; Harriss, Robert; Herndon, Scott C.; Karion, Anna; Kort, Eric Adam; Lamb, Brian K.; Lan, Xin; Marchese, Anthony J.; Pacala, Stephen W.; Robinson, Allen L.; Shepson, Paul B.; Sweeney, Colm; Talbot, Robert; Townsend-Small, Amy; Yacovitch, Tara I.; Zimmerle, Daniel J.; Hamburg, Steven P.

    2015-01-01

    Published estimates of methane emissions from atmospheric data (top-down approaches) exceed those from source-based inventories (bottom-up approaches), leading to conflicting claims about the climate implications of fuel switching from coal or petroleum to natural gas. Based on data from a coordinated campaign in the Barnett Shale oil and gas-producing region of Texas, we find that top-down and bottom-up estimates of both total and fossil methane emissions agree within statistical confidence intervals (relative differences are 10% for fossil methane and 0.1% for total methane). We reduced uncertainty in top-down estimates by using repeated mass balance measurements, as well as ethane as a fingerprint for source attribution. Similarly, our bottom-up estimate incorporates a more complete count of facilities than past inventories, which omitted a significant number of major sources, and more effectively accounts for the influence of large emission sources using a statistical estimator that integrates observations from multiple ground-based measurement datasets. Two percent of oil and gas facilities in the Barnett accounts for half of methane emissions at any given time, and high-emitting facilities appear to be spatiotemporally variable. Measured oil and gas methane emissions are 90% larger than estimates based on the US Environmental Protection Agency’s Greenhouse Gas Inventory and correspond to 1.5% of natural gas production. This rate of methane loss increases the 20-y climate impacts of natural gas consumed in the region by roughly 50%. PMID:26644584

  11. The phase transformation of methane caused by pressure change during its rising from seepage, revealed by video　observation　and acoustic reflection data

    NASA Astrophysics Data System (ADS)

    Aoyama, D.; Aoyama, C.

    2014-12-01

    The plume comes out to the surface of the water, and methane is released for low water temperature and low temperature in the Arctic Ocean by the atmosphere. Methane released by the atmosphere is combined with oxygen and becomes carbon dioxide and the water, and the greenhouse effect is higher in 20 times than carbon dioxide. If quantity of the　methane　plume is quantified, I may estimate the quantity of existing methane underground and can estimate the scale of methane melting into it in seawater. The　methane　plume solved in seawater is one element of the carbon cycle. It is important that I elucidate this element in thinking about the carbon cycle of the wide sense.　However, there is not the report that I showed quantitatively how much methane melts into it in seawater a year from the methane plume. Therefore, in this article, I identified an aspect of gush methane as it by the sound data with the fishfinder and by a gush picture of the methane plume. With that in mind, I quantified the quantity of the methane plume. As a result, the following things became clear. The methane hydrate grain to gush out from a gush mouth is a solid at the bottom of the sea direct top. In this sea area, methane of 7.7*104m3 per unit area gushes out. In addition, the sea area where 6.3*106m3 gushed out existed.

  12. Rate constants for reactions of ClO/x/ of atmospheric interest

    NASA Technical Reports Server (NTRS)

    Watson, R. T.

    1977-01-01

    Chemical kinetics measurements on 82 gas phase reactions of chlorine containing species are reviewed. Recommended rate constants are given. The principal species of interest are Cl, Cl2, ClO, Cl2O, ClOO, OClO, CINO, HCl and halo derivatives of methane and ethane. Absorption spectra are given for 21 species. In addition the chemical kinetics methods used to obtain these data are discussed with regard to their applicability and reliability.

  13. Detection of abundant ethane and methane, along with carbon monoxide and water, in comet C/1996 B2 Hyakutake: evidence for interstellar origin

    NASA Technical Reports Server (NTRS)

    Mumma, M. J.; DiSanti, M. A.; Dello Russo, N.; Fomenkova, M.; Magee-Sauer, K.; Kaminski, C. D.; Xie, D. X.

    1996-01-01

    The saturated hydrocarbons ethane (C2H6) and methane (CH4) along with carbon monoxide (CO) and water (H2O) were detected in comet C/1996 B2 Hyakutake with the use of high-resolution infrared spectroscopy at the NASA Infrared Telescope Facility on Mauna Kea, Hawaii. The inferred production rates of molecular gases from the icy, cometary nucleus (in molecules per second) are 6.4 X 10(26) for C2H6, 1.2 X 10(27) for CH4, 9.8 X 10(27) for CO, and 1.7 X 10(29) for H2O. An abundance of C2H6 comparable to that of CH4 implies that ices in C/1996 B2 Hyakutake did not originate in a thermochemically equilibrated region of the solar nebula. The abundances are consistent with a kinetically controlled production process, but production of C2H6 by gas-phase ion molecule reactions in the natal cloud core is energetically forbidden. The high C2H6/CH4 ratio is consistent with production of C2H6 in icy grain mantles in the natal cloud, either by photolysis of CH4-rich ice or by hydrogen-addition reactions to acetylene condensed from the gas phase.

  14. Baseline assessment of groundwater quality in Wayne County, Pennsylvania, 2014

    USGS Publications Warehouse

    Senior, Lisa A.; Cravotta, III, Charles A.; Sloto, Ronald A.

    2016-06-30

    The Devonian-age Marcellus Shale and the Ordovician-age Utica Shale, geologic formations which have potential for natural gas development, underlie Wayne County and neighboring counties in northeastern Pennsylvania. In 2014, the U.S. Geological Survey, in cooperation with the Wayne Conservation District, conducted a study to assess baseline shallow groundwater quality in bedrock aquifers in Wayne County prior to potential extensive shale-gas development. The 2014 study expanded on previous, more limited studies that included sampling of groundwater from 2 wells in 2011 and 32 wells in 2013 in Wayne County. Eighty-nine water wells were sampled in summer 2014 to provide data on the presence of methane and other aspects of existing groundwater quality throughout the county, including concentrations of inorganic constituents commonly present at low levels in shallow, fresh groundwater but elevated in brines associated with fluids extracted from geologic formations during shale-gas development. Depths of sampled wells ranged from 85 to 1,300 feet (ft) with a median of 291 ft. All of the groundwater samples collected in 2014 were analyzed for bacteria, major ions, nutrients, selected inorganic trace constituents (including metals and other elements), radon-222, gross alpha- and gross beta-particle activity, selected man-made organic compounds (including volatile organic compounds and glycols), dissolved gases (methane, ethane, and propane), and, if sufficient methane was present, the isotopic composition of methane.Results of the 2014 study show that groundwater quality generally met most drinking-water standards, but some well-water samples had one or more constituents or properties, including arsenic, iron, pH, bacteria, and radon-222, that exceeded primary or secondary maximum contaminant levels (MCLs). Arsenic concentrations were higher than the MCL of 10 micrograms per liter (µg/L) in 4 of 89 samples (4.5 percent) with concentrations as high as 20 µg/L; arsenic concentrations were higher than the Health Advisory level of 2 µg/L in 27 of 89 samples (30 percent). Total iron concentrations exceeded the secondary maximum contaminant level (SMCL) of 300 µg/L in 9 of 89 samples (10 percent). The pH ranged from 5.4 to 9.3 and did not meet the SMCL range of greater than 6.5 to less than 8.5 in 27 samples (30 percent); 22 samples had pH values less than 6.5, and 5 samples had pH values greater than 8.5. Total coliform bacteria were detected in 22 of 89 samples (25 percent); Escherichia coli were detected in only 2 of those 22 samples. Radon-222 activities ranged from 25 to 7,400 picocuries per liter (pCi/L), with a median of 2,120 pCi/L, and exceeded the proposed drinking-water standard of 300 pCi/L in 86 of 89 samples (97 percent); radon-222 activities were higher than the alternative proposed standard of 4,000 pCi/L in 12 of 89 samples (13.5 percent).Water from 8 of the 89 wells (9 percent) had concentrations of methane greater than the reporting level of 0.24 milligrams per liter (mg/L) with the detectable methane concentrations ranging from 0.74 to 9.6 mg/L. Of 16 replicate samples submitted to another laboratory with a lower reporting level of 0.0002 mg/L, 15 samples had detectable methane concentrations that ranged from 0.0011 to 9.7 mg/L. Of these 15 samples, low levels of ethane (0.00032 to 0.0017 mg/L) were detected in 6 of 7 samples with methane concentrations greater than 0.75 mg/L. The isotopic composition of methane in 6 of 8 samples with sufficient dissolved methane (about 1 mg/L) for isotopic analysis is consistent with a predominantly thermogenic methane source (sample carbon isotopic ratio δ13CCH4 values ranging from -56.36 to -45.97 parts per thousand (‰) and hydrogen isotopic ratio δDCH4 values ranging from -233.1 to -141.1 ‰). However, the low levels of ethane relative to methane indicate that the methane may be of microbial origin and subsequently underwent oxidation. Isotopic compositions indicated a possibly mixed thermogenic and microbial source (carbon dioxide reduction process) for the methane in 1 of the 8 samples (δ13CCH4 of -63.72 and δDCH4 of -192.3 ‰) and potential oxidation of microbial and (or) thermogenic methane in the remaining sample (δ13CCH4 of -46.56 and δDCH4 of -79.7 ‰).Groundwater samples with relatively elevated methane concentrations (near or greater than 1 mg/L) had a chemical composition that differed in some respects (pH, selected major ions, and inorganic trace constituents) from groundwater with relatively low methane concentrations (less than 0.75 mg/L). The seven well-water samples with the highest methane concentrations (from about 1 to 9.6 mg/L) also had among the highest pH values (8.1 to 9.3, respectively) and the highest concentrations of sodium, lithium, boron, fluoride, arsenic, and bromide. Relatively elevated concentrations of some other constituents, such as barium, strontium, and chloride, commonly were present in, but not limited to, those well-water samples with elevated methane.Groundwater samples with the highest methane concentrations had chloride/bromide ratios that indicate mixing with a small amount of brine (0.02 percent or less, by volume) similar in composition to that reported for gas and oil well brines in Pennsylvania. Most other samples with low methane concentrations (less than about 1 mg/L) had chloride/bromide ratios that indicate predominantly man-made sources of chloride, such as road salt, septic systems, and (or) animal waste. Although naturally occurring brines may originate from deeper parts of the aquifer system, the man-made sources are likely to affect shallow groundwater.Geochemical modeling showed that the water chemistry of samples with elevated pH, sodium, lithium, bromide, and alkalinity could result from dissolution of calcite (calcium carbonate) combined with cation exchange and mixing with a small amount of brine. Through cation exchange reactions (which are equivalent to processes in a water softener) calcium ions released by calcite dissolution are exchanged for sodium ions on clay minerals. The spatial distribution of groundwater compositions generally shows that (1) relatively dilute, slightly acidic, oxygenated, calcium-carbonate type waters tend to occur in the uplands along the western border of Wayne County; (2) waters of near neutral pH with the highest amounts of hardness (calcium and magnesium) generally occur in areas of intermediate altitudes; and (3) waters with pH values greater than 8, low oxygen concentrations, and the highest arsenic, sodium, lithium, bromide, and methane concentrations can occur in deep wells in uplands but most frequently occur in stream valleys, especially at low elevations (less than about 1,200 ft above North American Vertical Datum of 1988) where groundwater may be discharging regionally, such as to the Delaware River. Thus, the baseline assessment of groundwater quality in Wayne County prior to gas-well development shows that shallow (less than about 1,000 ft deep) groundwater is generally of good quality, but methane and some constituents present in high concentrations in brine (and produced waters from gas and oil wells) may be present at low to moderate concentrations in some parts of Wayne County.

  15. The 1992-1993 advanced design program. Part 1: The Mars methane engine project. Part 2: The Mars oxygen processor new furnace

    NASA Astrophysics Data System (ADS)

    Lauer, Stephen; Hoover, Scott; Lawrence, Lori; Paparistodemou, Christos; Taylor, Doug

    1993-04-01

    Three constituents of the Martian atmosphere, methane, carbon dioxide, and oxygen, can be used for internal combustion in engines utilized for future space exploration on Mars. These three gases, considered as the test case in this research, will be examined to determine required flow rates needed for combustion and optimization of engine performance. Results of the test case are examined in relation to a base case of methane and air for comparative purposes. Testing of exhaust temperatures, cylinder pressure, and exhaust gas analysis were performed for the base case and test case. Also described is a study utilizing a zirconia cell to convert carbon dioxide into usable oxygen to help support future Mars missions.

  16. The 1992-1993 advanced design program. Part 1: The Mars methane engine project. Part 2: The Mars oxygen processor new furnace

    NASA Technical Reports Server (NTRS)

    Lauer, Stephen; Hoover, Scott; Lawrence, Lori; Paparistodemou, Christos; Taylor, Doug

    1993-01-01

    Three constituents of the Martian atmosphere, methane, carbon dioxide, and oxygen, can be used for internal combustion in engines utilized for future space exploration on Mars. These three gases, considered as the test case in this research, will be examined to determine required flow rates needed for combustion and optimization of engine performance. Results of the test case are examined in relation to a base case of methane and air for comparative purposes. Testing of exhaust temperatures, cylinder pressure, and exhaust gas analysis were performed for the base case and test case. Also described is a study utilizing a zirconia cell to convert carbon dioxide into usable oxygen to help support future Mars missions.

  17. Investigation of the microbial metabolism of carbon dioxide and hydrogen in the kangaroo foregut by stable isotope probing

    PubMed Central

    Godwin, Scott; Kang, Alicia; Gulino, Lisa-Maree; Manefield, Mike; Gutierrez-Zamora, Maria-Luisa; Kienzle, Marco; Ouwerkerk, Diane; Dawson, Kerri; Klieve, Athol V

    2014-01-01

    Kangaroos ferment forage material in an enlarged forestomach analogous to the rumen, but in contrast to ruminants, they produce little or no methane. The objective of this study was to identify the dominant organisms and pathways involved in hydrogenotrophy in the kangaroo forestomach, with the broader aim of understanding how these processes are able to predominate over methanogenesis. Stable isotope analysis of fermentation end products and RNA stable isotope probing (RNA-SIP) were used to investigate the organisms and biochemical pathways involved in the metabolism of hydrogen and carbon dioxide in the kangaroo forestomach. Our results clearly demonstrate that the activity of bacterial reductive acetogens is a key factor in the reduced methane output of kangaroos. In in vitro fermentations, the microbial community of the kangaroo foregut produced very little methane, but produced a significantly greater proportion of acetate derived from carbon dioxide than the microbial community of the bovine rumen. A bacterial operational taxonomic unit closely related to the known reductive acetogen Blautia coccoides was found to be associated with carbon dioxide and hydrogen metabolism in the kangaroo foregut. Other bacterial taxa including members of the genera Prevotella, Oscillibacter and Streptococcus that have not previously been reported as containing hydrogenotrophic organisms were also significantly associated with metabolism of hydrogen and carbon dioxide in the kangaroo forestomach. PMID:24621520

  18. Investigation of the microbial metabolism of carbon dioxide and hydrogen in the kangaroo foregut by stable isotope probing.

    PubMed

    Godwin, Scott; Kang, Alicia; Gulino, Lisa-Maree; Manefield, Mike; Gutierrez-Zamora, Maria-Luisa; Kienzle, Marco; Ouwerkerk, Diane; Dawson, Kerri; Klieve, Athol V

    2014-09-01

    Kangaroos ferment forage material in an enlarged forestomach analogous to the rumen, but in contrast to ruminants, they produce little or no methane. The objective of this study was to identify the dominant organisms and pathways involved in hydrogenotrophy in the kangaroo forestomach, with the broader aim of understanding how these processes are able to predominate over methanogenesis. Stable isotope analysis of fermentation end products and RNA stable isotope probing (RNA-SIP) were used to investigate the organisms and biochemical pathways involved in the metabolism of hydrogen and carbon dioxide in the kangaroo forestomach. Our results clearly demonstrate that the activity of bacterial reductive acetogens is a key factor in the reduced methane output of kangaroos. In in vitro fermentations, the microbial community of the kangaroo foregut produced very little methane, but produced a significantly greater proportion of acetate derived from carbon dioxide than the microbial community of the bovine rumen. A bacterial operational taxonomic unit closely related to the known reductive acetogen Blautia coccoides was found to be associated with carbon dioxide and hydrogen metabolism in the kangaroo foregut. Other bacterial taxa including members of the genera Prevotella, Oscillibacter and Streptococcus that have not previously been reported as containing hydrogenotrophic organisms were also significantly associated with metabolism of hydrogen and carbon dioxide in the kangaroo forestomach.

  19. Identification and characterization of high methane-emitting abandoned oil and gas wells

    PubMed Central

    Kang, Mary; Christian, Shanna; Celia, Michael A.; Mauzerall, Denise L.; Bill, Markus; Miller, Alana R.; Chen, Yuheng; Conrad, Mark E.; Darrah, Thomas H.; Jackson, Robert B.

    2016-01-01

    Recent measurements of methane emissions from abandoned oil/gas wells show that these wells can be a substantial source of methane to the atmosphere, particularly from a small proportion of high-emitting wells. However, identifying high emitters remains a challenge. We couple 163 well measurements of methane flow rates; ethane, propane, and n-butane concentrations; isotopes of methane; and noble gas concentrations from 88 wells in Pennsylvania with synthesized data from historical documents, field investigations, and state databases. Using our databases, we (i) improve estimates of the number of abandoned wells in Pennsylvania; (ii) characterize key attributes that accompany high emitters, including depth, type, plugging status, and coal area designation; and (iii) estimate attribute-specific and overall methane emissions from abandoned wells. High emitters are best predicted as unplugged gas wells and plugged/vented gas wells in coal areas and appear to be unrelated to the presence of underground natural gas storage areas or unconventional oil/gas production. Repeat measurements over 2 years show that flow rates of high emitters are sustained through time. Our attribute-based methane emission data and our comprehensive estimate of 470,000–750,000 abandoned wells in Pennsylvania result in estimated state-wide emissions of 0.04–0.07 Mt (1012 g) CH4 per year. This estimate represents 5–8% of annual anthropogenic methane emissions in Pennsylvania. Our methodology combining new field measurements with data mining of previously unavailable well attributes and numbers of wells can be used to improve methane emission estimates and prioritize cost-effective mitigation strategies for Pennsylvania and beyond. PMID:27849603

  20. Carbon isotope fractionation during microbial methane oxidation

    NASA Astrophysics Data System (ADS)

    Barker, James F.; Fritz, Peter

    1981-09-01

    Methane, a common trace constituent of groundwaters, occasionally makes up more than 20% of the total carbon in groundwaters1,2. In aerobic environments CH4-rich waters can enable microbial food chain supporting a mixed culture of bacteria with methane oxidation as the primary energy source to develop3. Such processes may influence the isotopic composition of the residual methane and because 13C/12C analyses have been used to characterize the genesis of methanes found in different environments, an understanding of the magnitude of such effects is necessary. In addition, carbon dioxide produced by the methane-utilizing bacteria can be added to the inorganic carbon pool of affected groundwaters. We found carbon dioxide experimentally produced by methane-utilizing bacteria to be enriched in 12C by 5.0-29.6‰, relative to the residual methane. Where methane-bearing groundwaters discharged into aerobic environments microbial methane oxidation occurred, with the residual methane becoming progressively enriched in 13C. Various models have been proposed to explain the 13C/12C and 14C content of the dissolved inorganic carbon (DIC) of groundwaters in terms of additions or losses during flow in the subsurface4,5. The knowledge of both stable carbon isotope ratios in various pools and the magnitude of carbon isotope fractionation during various processes allows geochemists to use the 13C/12C ratio of the DIC along with water chemistry to estimate corrected 14C groundwater ages4,5. We show here that a knowledge of the carbon isotope fractionation between CH4 and CO2 during microbial methane-utilization could modify such models for application to groundwaters affected by microbial methane oxidation.

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

    Holdridge, D. J.

    Global Warming and Methane--Global warming, an increase in Earth's near-surface temperature, is believed to result from the buildup of what scientists refer to as ''greenhouse gases.'' These gases include water vapor, carbon dioxide, methane, nitrous oxide, ozone, perfluorocarbons, hydrofluoro-carbons, and sulfur hexafluoride. Greenhouse gases can absorb outgoing infrared (heat) radiation and re-emit it back to Earth, warming the surface. Thus, these gases act like the glass of a greenhouse enclosure, trapping infrared radiation inside and warming the space. One of the more important greenhouse gases is the naturally occurring hydrocarbon methane. Methane, a primary component of natural gas, is themore » second most important contributor to the greenhouse effect (after carbon dioxide). Natural sources of methane include wetlands, fossil sources, termites, oceans, fresh-waters, and non-wetland soils. Methane is also produced by human-related (or anthropogenic) activities such as fossil fuel production, coal mining, rice cultivation, biomass burning, water treatment facilities, waste management operations and landfills, and domesticated livestock operations (Figure 1). These anthropogenic activities account for approximately 70% of the methane emissions to the atmosphere. Methane is removed naturally from the atmosphere in three ways. These methods, commonly referred to as sinks, are oxidation by chemical reaction with tropospheric hydroxyl ion, oxidation within the stratosphere, and microbial uptake by soils. In spite of their important role in removing excess methane from the atmosphere, the sinks cannot keep up with global methane production. Methane concentrations in the atmosphere have increased by 145% since 1800. Increases in atmospheric methane roughly parallel world population growth, pointing to anthropogenic sources as the cause (Figure 2). Increases in the methane concentration reduce Earth's natural cooling efficiency by trapping more of the outgoing terrestrial infrared radiation, increasing the near-surface temperature.« less

  2. Development of the Fabry-Perot Spectrometer Application

    NASA Technical Reports Server (NTRS)

    Browne, Kathryn

    2015-01-01

    Methane is a greenhouse gas with global warming effects 20 times more detrimental than carbon dioxide. Currently, only aircraft missions measure methane and do not provide continuous monitoring, This presentation will cover the Fabry-Perot spectrometer which will provide continuous monitoring of methane. It will also cover the development of the software used to extract and process the data the spectrometer collects.

  3. Carbon monoxide and methane adsorption of crude oil refinery using activated carbon from palm shells as biosorbent

    NASA Astrophysics Data System (ADS)

    Yuliusman; Afdhol, M. K.; Sanal, Alristo

    2018-03-01

    Carbon monoxide and methane gas are widely present in oil refineries. Off-potential gas is used as raw material for the petrochemical industry. In order for this off-gas to be utilized, carbon monoxide and methane must be removed from off-gas. This study aims to adsorb carbon monoxide and methane using activated carbon of palm shells and commercial activated carbon simultaneously. This research was conducted in 2 stages: 1) Preparation and characterization of activated carbon, 2) Carbon monoxide and methane adsorption test. The activation experiments using carbon dioxide at a flow rate of 150 ml/min yielded a surface area of 978.29 m2/g, Nitrogen at flow rate 150 ml/min yielded surface area 1241.48 m2/g, and carbon dioxide and nitrogen at a flow rate 200 ml/min yielded a surface area 300.37 m2/g. Adsorption of carbon monoxide and methane on activated carbon of palm shell systems yielded results in the amount of 0.5485 mg/g and 0.0649 mg/g and using commercial activated carbon yielded results in the amount of 0.5480 mg/g and 0.0650 mg/g

  4. Controls on Methane Occurrences in Aquifers Overlying the Eagle Ford Shale Play, South Texas.

    PubMed

    Nicot, Jean-Philippe; Larson, Toti; Darvari, Roxana; Mickler, Patrick; Uhlman, Kristine; Costley, Ruth

    2017-07-01

    Assessing natural vs. anthropogenic sources of methane in drinking water aquifers is a critical issue in areas of shale oil and gas production. The objective of this study was to determine controls on methane occurrences in aquifers in the Eagle Ford Shale play footprint. A total of 110 water wells were tested for dissolved light alkanes, isotopes of methane, and major ions, mostly in the eastern section of the play. Multiple aquifers were sampled with approximately 47 samples from the Carrizo-Wilcox Aquifer (250-1200 m depth range) and Queen City-Sparta Aquifer (150-900 m depth range) and 63 samples from other shallow aquifers but mostly from the Catahoula Formation (depth <150 m). Besides three shallow wells with unambiguously microbial methane, only deeper wells show significant dissolved methane (22 samples >1 mg/L, 10 samples >10 mg/L). No dissolved methane samples exhibit thermogenic characteristics that would link them unequivocally to oil and gas sourced from the Eagle Ford Shale. In particular, the well water samples contain very little or no ethane and propane (C1/C2+C3 molar ratio >453), unlike what would be expected in an oil province, but they also display relatively heavier δ 13 C methane (>-55‰) and δD methane (>-180‰). Samples from the deeper Carrizo and Queen City aquifers are consistent with microbial methane sourced from syndepositional organic matter mixed with thermogenic methane input, most likely originating from deeper oil reservoirs and migrating through fault zones. Active oxidation of methane pushes δ 13 C methane and δD methane toward heavier values, whereas the thermogenic gas component is enriched with methane owing to a long migration path resulting in a higher C1/C2+C3 ratio than in the local reservoirs. © 2017, National Ground Water Association.

  5. Adsorption of Natural Gas Mixtures in Nanoporos Carbon

    NASA Astrophysics Data System (ADS)

    Wexler, Carlos; Crawford-Goss, Ian; Lemke, Drew; Roth, Michael

    Natural gas (NG) is promising fuel due to its smaller CO2 emissions per unit energy compared to other hydrocarbons. Storage via adsorption into carbon nanostructures permits the operation of storage tanks at significantly reduced pressures, resulting in cost savings, added safety and smaller loss of cargo volume. Since NG is mostly comprised of methane (87-99%), other components are often ignored, even though heavier species are likely to adsorb preferentially and possibly result in long-term performance issues. We performed Molecular Dynamics (MD) simulations to understand the behavior of heavier components of NG adsorbed into carbon nanostructures. We focused on mixtures involving methane, ethane and propane. We show that the heavier components have significant preferential adsorption, partially inhibiting the adsorption of methane, and resulting in its saturation at lower pressures. Under room temperature conditions, propane adsorbs quasi irrevesibly, though remaining mobile within the pores. We discuss the diffusion regime of all gases and address methods to remove the adsorbed heavier gases by thermal cycling the tank. American Chemical Society Petroleum Research Fund.

  6. CHP Energy and Emissions Savings Calculator

    EPA Pesticide Factsheets

    Download the CHP Emissions Calculator, a tool that calculates the difference between the anticipated carbon dioxide, methane, nitrous oxide, sulfur dioxide, and nitrogen oxide emissions from a CHP system to those of a separate heat and power system.

  7. Methane fermentation process for utilization of organic waste

    NASA Astrophysics Data System (ADS)

    Frąc, M.; Ziemiński, K.

    2012-07-01

    Biogas is a renewable and sustainable energy carrier generated via anaerobic digestion of biomass. This fuel is derived from various biomass resources and depending on its origin it contains methane (40-75%), carbon dioxide (20-45%) and some other compounds. The aim of this paper is to present the current knowledge and prospects of using the methane fermentation process to dispose of various types of organic wastes as well as conditions and factors affecting the methane fermentation process.

  8. Mathematical model of the methane replacement by carbon dioxide in the gas hydrate reservoir taking into account the diffusion kinetics

    NASA Astrophysics Data System (ADS)

    Musakaev, N. G.; Khasanov, M. K.; Rafikova, G. R.

    2018-03-01

    The problem of the replacement of methane in its hydrate by carbon dioxide in a porous medium is considered. The gas-exchange kinetics scheme is proposed in which the intensity of the process is limited by the diffusion of CO2 through the hydrate layer formed between the gas mixture flow and the CH4 hydrate. Dynamics of the main parameters of the process is numerically investigated. The main characteristic stages of the process are determined.

  9. Lattice constants of pure methane and carbon dioxide hydrates at low temperatures. Implementing quantum corrections to classical molecular dynamics studies

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

    Costandy, Joseph; Michalis, Vasileios K.; Economou, Ioannis G., E-mail: i.tsimpanogiannis@qatar.tamu.edu, E-mail: ioannis.economou@qatar.tamu.edu

    2016-03-28

    We introduce a simple correction to the calculation of the lattice constants of fully occupied structure sI methane or carbon dioxide pure hydrates that are obtained from classical molecular dynamics simulations using the TIP4PQ/2005 water force field. The obtained corrected lattice constants are subsequently used in order to obtain isobaric thermal expansion coefficients of the pure gas hydrates that exhibit a trend that is significantly closer to the experimental behavior than previously reported classical molecular dynamics studies.

  10. Low temperature rate coefficients for the reactions of 1CH2 with reactive and non-reactive species, and the implications for Titan's atmosphere

    NASA Astrophysics Data System (ADS)

    Douglas, Kevin; Slater, Eloise; Blitz, Mark; Plane, John; Heard, Dwayne; Seakins, Paul

    2016-04-01

    The Cassini-Huygens mission to Titan revealed unexpectedly large amounts of benzene in the troposphere, and confirmed the absence of a global ethane ocean as predicted by photochemical models of methane conversion over the lifetime of the solar system. An important chemical intermediate in both the production and loss of benzene and ethane is the first electronically excited state of methylene, 1CH2. For example, at room temperature an important reaction of 1CH2 is with acetylene (R1a), leading to the formation of propargyl (C3H3)[1]. The subsequent recombination of propargyl radicals is the major suggested route to benzene in Titan's atmosphere (R2)[2]. In addition to reaction of 1CH2 leading to products, there is also competition between inelastic electronic relaxation to form the ground triplet state 3CH2 (R1b). This ground state 3CH2 has a markedly different reactivity to the singlet, reacting primarily with methyl radicals (CH3) to form ethene (R3). As methyl radical recombination is the primary route to ethane (R4)[3], reactions of 1CH2 will also heavily influence the ethane budget on Titan. 1CH2 + C2H2 → C3H3 + H (R1a) 1CH2 + C2H2 → 3CH2 + C2H2 (R1b) C3H3 + C3H3 → C6H6 (R2) 3CH2 + CH3 → C2H4 + H (R3) CH3 + CH3 (+ M) → C2H6 (R4) Thus this competition between chemical reaction and electronic relaxation in the reactions of 1CH2 with H2, CH4, C2H4, and C2H6 will play an important role in determining the benzene and ethane budgets on Titan. Despite this there are no measurements of any rate constants for 1CH2 at temperatures relevant to Titan's atmosphere (60 - 170 K). Using a pulsed Laval nozzle apparatus coupled with pulsed laser photolysis laser-induced fluorescence, the low temperature reaction kinetics for the removal of 1CH2 with nitrogen, hydrogen, methane, ethane, ethene, acetylene, and oxygen, have been studied. The results revealed an increase in the removal rate of 1CH2 at temperatures below 200 K, with a sharp increase of around a factor of 5 observed at 45±5 K. In addition to measuring total removal rates of 1CH2, the fraction of 1CH2 removed via electronic relaxation verses chemical reaction to products has also been investigated. Results for the reactive species ethane, ethene, and acetylene at 45±5 K, and for hydrogen and methane at 73±9 K indicate that following reactions with 1CH2, removal of 1CH2 is predominantly due to electronic relaxation (> 95 %) and not chemical reaction to products. This is in agreement with previous studies that show that with decreasing temperature, the fraction of reactive removal of 1CH2 to chemical products decreases while the fraction of removal by electronic relaxation increases[4][5]. These results indicate that 1CH2 formed in Titan's atmosphere will be rapidly relaxed to it's ground state via collisions with both reactive and non-reactive species, and thus will play a less significant role in the formation of larger hydrocarbons than previously thought. However for a full understanding of the implications of these results, the new measurements are to be included in a 1D model of Titan's atmosphere to determine the impact of the laboratory measurements on observation/model agreement. [1] K. Gannon et. al., J. Phys. Chem. A, (2010), 114, 9413 [2] E.H. Wilson, S.K. Atreya, J. Geophys. Res., (2004), 109, 6002 [3] M. Fulchignoni, Nature, (2005), 438, 785 [4] K. Gannon, Faraday Discuss., (2010), 147, 173 [5] K. Gannon, J. Phys. Chem. A, (2008), 112, 9575

  11. Robust IR Remote Sensing Technique of the Total Column of Trace Gases Including Carbon Dioxide and Methane

    NASA Technical Reports Server (NTRS)

    Georgieva, E. M.; Heaps, W. S.

    2011-01-01

    Progress on the development of a differential radiometer based upon the Fabry-Perot interferometer (FPI) for methane (CH4) and carbon dioxide (C02) detection in the atmosphere is presented. Methane measurements are becoming increasingly important as a component of NASA's programs to understand the global carbon cycle and quantifY the threat of global warming. Methane is the third most important greenhouse gas in the Earth's radiation budget (after water vapor and carbon dioxide) and the second most important anthropogenic contributor to global warming. The importance of global warming and air quality to society caused the National Research Council to recommend that NASA develop the following missions [1]: ASCENDS (Active Sensing of C02 Emissions over Nights, Days, and Seasons), GEOCAPE (Geostationary Coastal and Air Pollution Events), and GACM (Global Atmosphere Composition Mission). Though methane measurements are not specifically called out in these missions, ongoing environmental changes have raised the importance of understanding the methane budget. In the decadal survey is stated that "to close the carbon budget, we would also address methane, but the required technology is not obvious at this time. If appropriate and cost-effective methane technology becomes available, we strongly recommend adding a methane capability". In its 2007 report the International Panel on Climate Change identified methane as a key uncertainty in our understanding saying that the causes of recent changes in the growth rate of atmospheric CH4 are not well understood. What we do know is that methane arises from a number of natural sources including wet lands and the oceans plus man made sources from agriculture, as well as coal and petroleum production and distribution. It has recently been pointed out that large amount of methane are frozen in the permafrost of Canada and Siberia. There is a fear that melting of this permafrost driven by global warming may release large amounts of methane very suddenly further exacerbating climate change [2]. Last year our group began a joint effort with Johns Hopkins Applied Physics Laboratory to investigate the possibility of developing a small unmanned aerial vehicle (UAV) equipped to measure greenhouse gases-particularly methane. Although we are targeting our system for smaller UAV's the instrument will be directly applicable to missions involving larger NASA UAV's such as Global Hawk or even on missions utilizing manned aircraft. Because of its small size, inherent ruggedness and simplicity some version of our proposed instrument may find a role as a satellite instrument for NASA or NOAA.

  12. Aqueous Mesocosm Techniques Enabling the Real-Time Measurement of the Chemical and Isotopic Kinetics of Dissolved Methane and Carbon Dioxide.

    PubMed

    Chan, Eric W; Kessler, John D; Shiller, Alan M; Joung, DongJoo; Colombo, Frank

    2016-03-15

    Previous studies of microbially mediated methane oxidation in oceanic environments have examined the many different factors that control the rates of oxidation. However, there is debate on what factor(s) are limiting in these types of environments. These factors include the availability of methane, O2, trace metals, nutrients, the density of cell population, and the influence that CO2 production may have on pH. To look at this process in its entirety, we developed an automated mesocosm incubation system with a Dissolved Gas Analysis System (DGAS) coupled to a myriad of analytical tools to monitor chemical changes during methane oxidation. Here, we present new high temporal resolution techniques for investigating dissolved methane and carbon dioxide concentrations and stable isotopic dynamics during aqueous mesocosm and pure culture incubations. These techniques enable us to analyze the gases dissolved in solution and are nondestructive to both the liquid media and the analyzed gases enabling the investigation of a mesocosm or pure culture experiment in a completely closed system, if so desired.

  13. Effects of titanium dioxide and zinc oxide nanoparticles on methane production from anaerobic co-digestion of primary and excess sludge.

    PubMed

    Zheng, Xiong; Wu, Lijuan; Chen, Yinguang; Su, Yinglong; Wan, Rui; Liu, Kun; Huang, Haining

    2015-01-01

    Anaerobic co-digestion of primary and excess sludge is regarded as an efficient way to reuse sludge organic matter to produce methane. In this study, short-term and long-term exposure experiments were conducted to investigate the possible effects of titanium dioxide (TiO2) and zinc oxide (ZnO) nanoparticles (NPs) on methane production from anaerobic co-digestion of primary and excess sludge. The data showed that TiO2 NPs had no measurable impact on methane production, even at a high concentration (150 mg/g total suspended solids (TSS)). However, short-term (8 days) exposure to 30 or 150 mg/g-TSS of ZnO NPs significantly decreased methane production. More importantly, these negative effects of ZnO NPs on anaerobic sludge co-digestion were not alleviated by increasing the adaptation time to 105 days. Further studies indicated that the presence of ZnO NPs substantially decreased the abundance of methanogenic archaea, which reduced methane production. Meanwhile, the activities of some key enzymes involved in methane production, such as protease, acetate kinase, and coenzyme F420, were remarkably inhibited by the presence of ZnO NPs, which was also an important reason for the decreased methane production. These results provide a better understanding of the potential risks of TiO2 and ZnO NPs to methane production from anaerobic sludge co-digestion.

  14. Microbial Oxidation of Natural Gas in a Plume Emanating from the Coal Oil Point Seep Field

    NASA Astrophysics Data System (ADS)

    Mendes, S. D.; Valentine, D. L.; Perez, C.; Scarlett, R.

    2012-12-01

    The hydrocarbon seep field at Coal Oil Point, off the coast of Santa Barbara, California, releases > 1010 g of thermogenic natural gas each year. Gases emitted from Coal Oil Point include methane, ethane, propane, and butane, which are atmospheric pollutants and greenhouse gases. Even though the seeps are at water depths of only 5-80 m, much of the gas dissolves and contributes to a plume that is transported by ocean currents. While hydrocarbons can support bacterial respiration, resulting in the removal of hydrocarbon gas from the plume, the time-scale for the bacterial respiratory response is unconstrained. To track hydrocarbon respiration 3H-ethane, propane, and butane were synthesized using Grignard reagents and tritiated water with yields of >70% and applied as tracers to samples up- and down-current from the seeps at Coal Oil Point. Validation experiments conducted in September 2011 aboard the R/V Atlantis show that 3H-labeled tracers are an order of magnitude more sensitive than previous methods using stable carbon isotopes (Valentine et. al 2010), making this technique preferable in natural systems. Application of the tracers concurrent with plume tracking in July-August 2012 show ethane, propane, and butane consumption are readily inducible on a timescale of days.

  15. Titan and habitable planets around M-dwarfs.

    PubMed

    Lunine, Jonathan I

    2010-01-01

    The Cassini-Huygens mission discovered an active "hydrologic cycle" on Saturn's giant moon Titan, in which methane takes the place of water. Shrouded by a dense nitrogen-methane atmosphere, Titan's surface is blanketed in the equatorial regions by dunes composed of solid organics, sculpted by wind and fluvial erosion, and dotted at the poles with lakes and seas of liquid methane and ethane. The underlying crust is almost certainly water ice, possibly in the form of gas hydrates (clathrate hydrates) dominated by methane as the included species. The processes that work the surface of Titan resemble in their overall balance no other moon in the solar system; instead, they are most like that of the Earth. The presence of methane in place of water, however, means that in any particular planetary system, a body like Titan will always be outside the orbit of an Earth-type planet. Around M-dwarfs, planets with a Titan-like climate will sit at 1 AU--a far more stable environment than the approximately 0.1 AU where Earth-like planets sit. However, an observable Titan-like exoplanet might have to be much larger than Titan itself to be observable, increasing the ratio of heat contributed to the surface atmosphere system from internal (geologic) processes versus photons from the parent star.

  16. Guidance on Risk Analysis and Safety Implications of a Large Liquefied Natural Gas (LNG) Spill Over Water

    DTIC Science & Technology

    2004-12-01

    Explosive Materials/Subsystems Don Ragland, Technical Writer/Editor Energy Infrastructure and DER Department Sandia National Laboratories P.O. Box 5800...and the culvert measured 2.4 meters in diameter. From these detonations, the shock wave was felt at a town 22 km from the test site. Vander Molen ...and Nicholls – 1979 [Vander Molen and Nicholls 1979] Experiments were performed to measure the effect of ethane addition to methane air clouds on

  17. Gas Phase Ion-Molecule Chemistry of Carbon, Nitrogen and Oxygen Compounds.

    DTIC Science & Technology

    1985-01-29

    silyl anions aza allyl anion) phosphide anion sulfides) Reactivity; nitrite estersj electron affinityMechanism’, sulfur dioxidej. (cont’d) M L..J A6*rAcr...use of silane chemistry to attack a problem of fundamental importance to all organic chemistry, the relative acidity of the alkanes.20 While it is well...alkane lost are a measure of the relative acidity of RH. For example, because ethane is lost less easily than methane, we believe that the ethyl anion

  18. Trace-gas metabolic versatility of the facultative methanotroph Methylocella silvestris.

    PubMed

    Crombie, Andrew T; Murrell, J Colin

    2014-06-05

    The climate-active gas methane is generated both by biological processes and by thermogenic decomposition of fossil organic material, which forms methane and short-chain alkanes, principally ethane, propane and butane. In addition to natural sources, environments are exposed to anthropogenic inputs of all these gases from oil and gas extraction and distribution. The gases provide carbon and/or energy for a diverse range of microorganisms that can metabolize them in both anoxic and oxic zones. Aerobic methanotrophs, which can assimilate methane, have been considered to be entirely distinct from utilizers of short-chain alkanes, and studies of environments exposed to mixtures of methane and multi-carbon alkanes have assumed that disparate groups of microorganisms are responsible for the metabolism of these gases. Here we describe the mechanism by which a single bacterial strain, Methylocella silvestris, can use methane or propane as a carbon and energy source, documenting a methanotroph that can utilize a short-chain alkane as an alternative to methane. Furthermore, during growth on a mixture of these gases, efficient consumption of both gases occurred at the same time. Two soluble di-iron centre monooxygenase (SDIMO) gene clusters were identified and were found to be differentially expressed during bacterial growth on these gases, although both were required for efficient propane utilization. This report of a methanotroph expressing an additional SDIMO that seems to be uniquely involved in short-chain alkane metabolism suggests that such metabolic flexibility may be important in many environments where methane and short-chain alkanes co-occur.

  19. Generation of ethylene tracer by noncatalytic pyrolysis of natural gas at elevated pressure

    USGS Publications Warehouse

    Lu, Y.; Chen, S.; Rostam-Abadi, M.; Ruch, R.; Coleman, D.; Benson, L.J.

    2005-01-01

    There is a critical need within the pipeline gas industry for an inexpensive and reliable technology to generate an identification tag or tracer that can be added to pipeline gas to identify gas that may escape and improve the deliverability and management of gas in underground storage fields. Ethylene is an ideal tracer, because it does not exist naturally in the pipeline gas, and because its physical properties are similar to the pipeline gas components. A pyrolysis process, known as the Tragen process, has been developed to continuously convert the ???2%-4% ethane component present in pipeline gas into ethylene at common pipeline pressures of 800 psi. In our studies of the Tragen process, pyrolysis without steam addition achieved a maximum ethylene yield of 28%-35% at a temperature range of 700-775 ??C, corresponding to an ethylene concentration of 4600-5800 ppm in the product gas. Coke deposition was determined to occur at a significant rate in the pyrolysis reactor without steam addition. The ?? 13C isotopic analysis of gas components showed a ?? 13C value of ethylene similar to ethane in the pipeline gas, indicating that most of the ethylene was generated from decomposition of the ethane in the raw gas. However, ?? 13C isotopic analysis of the deposited coke showed that coke was primarily produced from methane, rather than from ethane or other heavier hydrocarbons. No coke deposition was observed with the addition of steam at concentrations of > 20% by volume. The dilution with steam also improved the ethylene yield. ?? 2005 American Chemical Society.

  20. Methane Dynamics in Flooded Lands

    EPA Science Inventory

    Methane (CH4) is the second most important anthropogenic greenhouse gas with a heat trapping capacity 34 times greater than that of carbon dioxide on a100 year time scale. Known anthropogenic CH4 sources include livestock production, rice agriculture, landfills, and natural gas m...

  1. Organic History and Ice-Rock Decoupling on Enceladus

    NASA Astrophysics Data System (ADS)

    Zolotov, M. Y.

    2007-12-01

    The Cassini detection of methane, propane and acetylene in the Enceladus plume, and condensed organic compounds (OC) on the south polar region imply an organic-bearing interior of the moon. At least a few wt. % of C is expected in rocks from which Enceladus accreted. By analogy with carbonaceous chondrites, the majority of accreted OC was in a polymer in which polyaromatic groups are linked by O-, N-, and S-bearing aliphatic units. If accreted, cometary-type materials also delivered CO2, CO(?), methanol, ethane, ethene, acetylene, and condensed OC. Subsequent water ice melting and hydrothermal processes driven by decay of short-lived radionuclides led to dissolution of CO, CO2 and methanol in water and transformations of the polymer and cometary OC. CO converted to formic acid, carbonate species, methanol and methane. Hydrous pyrolysis and oxidation of the polymer partially liberated aromatic molecules and led to the formation of O-bearing OC (carboxylic and amino acids, alcohols). Increase in temperature favored oxidation of OC to carbonate species and N2, and led to graphitization of the polymer. Despite net oxidation of OC driven by H2 escape, mineral- catalyzed Fisher-Tropsch like synthesis of hydrocarbons and methane occurred in H2-rich niches. As a result, an array of aromatic, aliphatic, and N-, O-, S-bearing OC, and methane was delivered into a primordial water ocean in hydrothermal fluids. Highly soluble OC (acids, alcohols) made multiple passes through hydrothermal systems causing further oxidation of OC in rocks and solutions. In contrast, hydrocarbons exolved from cold oceanic water and formed an organic layer below the ice shell. Subsequent cooling of ocean-entering fluids and ocean freezing from above led to further separation and accumulation of OC. Some OC was trapped in ice, and methane formed clathrates. After freezing of salt eutectic brines, the light oil (a solution/mixture of ethane, propane, butane, ethene, acetylene, methanol, toluene etc.) remained unfrozen and decoupled the ice shell from underlying salt deposits and rocks. Even after oil solidification, if it occurred, the organic layer had a lower viscosity than salts and ice. An uneven pressure and/or topography at the ice-salt boundary could have led to preferential oil (and salt?) accumulation below the south polar region. Throughout history (and today), the uneven oil-rich layer could have favored tidal motions and heat generation at the bottom of the ice shell.

  2. Methane Post-Processing for Oxygen Loop Closure

    NASA Technical Reports Server (NTRS)

    Greenwood, Zachary W.; Abney, Morgan B.; Miller, Lee

    2016-01-01

    State-of-the-art United States Atmospheric Revitalization carbon dioxide (CO2) reduction is based on the Sabatier reaction process, which recovers approximately 50% of the oxygen (O2) from crew metabolic CO2. Oxygen recovery from carbon dioxide is constrained by the limited availability of reactant hydrogen. Post-processing of methane to recover hydrogen with the Umpqua Research Company Plasma Pyrolysis Assembly (PPA) has the potential to further close the Atmospheric Revitalization oxygen loop. The PPA decomposes methane into hydrogen and hydrocarbons, predominantly acetylene, and a small amount of solid carbon. The hydrogen must then be purified before it can be recycled for additional oxygen recovery. Long duration testing and evaluation of a four crew-member sized PPA and a discussion of hydrogen recycling system architectures are presented.

  3. Greenhouse gases: low methane leakage from gas pipelines.

    PubMed

    Lelieveld, J; Lechtenböhmer, S; Assonov, S S; Brenninkmeijer, C A M; Dienst, C; Fischedick, M; Hanke, T

    2005-04-14

    Using natural gas for fuel releases less carbon dioxide per unit of energy produced than burning oil or coal, but its production and transport are accompanied by emissions of methane, which is a much more potent greenhouse gas than carbon dioxide in the short term. This calls into question whether climate forcing could be reduced by switching from coal and oil to natural gas. We have made measurements in Russia along the world's largest gas-transport system and find that methane leakage is in the region of 1.4%, which is considerably less than expected and comparable to that from systems in the United States. Our calculations indicate that using natural gas in preference to other fossil fuels could be useful in the short term for mitigating climate change.

  4. Methane and carbon dioxide concentrations in sediments and diffusive fluxes at the sediment-water interface from three tropical systems in Brazil during the pre-impoundment phase

    NASA Astrophysics Data System (ADS)

    Abe, D. S.; Sidagis-Galli, C.; Grimberg, D. E.; Blanco, F. D.; Rodrigues-Filho, J. L.; Tundisi, J. G.; Matsumura-Tundisi, T.; Tundisi, J. E.; Cimbleris, A. C.; Damázio, J. M.; Project Balcar

    2013-05-01

    The concentrations of methane and carbon dioxide in the sediments pore water were quantified by gas chromatography in three hydroelectric reservoirs under construction during the pre-impoundment phase. Sediment sampling was performed in ten to twelve stations in each river by a Kajak-Brinkhurst corer coupled to a 3 m long aluminum rod in four seasons. The theoretical diffusive fluxes of these gases at the sediment-water interface were also calculated using the Fick's first law of diffusion. The mean annual concentration and diffusive flux of methane were highest in the sediments of the Xingu River (12.71 ± 3.03 mmol CH4 m-2 and 3.84 ± 0.91 mmol CH4 m-2 d-1), located in the Amazon, influenced by the presence of organic matter originating from the surrounding forest. The mean annual concentration of carbon dioxide was highest in the São Marcos River (71.36 ± 10.36 mmol CO2 m-2), located in an area of cerrado savanna, while the highest diffusive flux of carbon dioxide was observed in the Madeira River (30.23 ± 2.41 mmol CO2 m-2 d-1), which rises in the Andes Cordillera and has a very high water flow. The mean concentration and diffusive flux of carbon dioxide in the three studied systems were much higher (64-98%) in comparison with the methane, influenced by the oxic condition in these lotic systems. Nevertheless, the present study shows that the sediments of these systems, especially in the Xingu River, have significant amount of methane dissolved in the pore water which is being diffused to the overlying water. The information obtained in this study during the pre-filling phase will be important for the calculation of net flows of greenhouse gases after the impoundment of these future reservoirs. This study is part of the Strategic Project "Monitoring Emissions of Greenhouse Gases in Hydroelectric Reservoirs" - Call 099/2008 of the Brazilian Agency of Electric Energy (ANEEL) and sponsored by ELETRONORTE, FURNAS and CHESF.

  5. Membrane-augmented cryogenic methane/nitrogen separation

    DOEpatents

    Lokhandwala, Kaaeid

    1997-01-01

    A membrane separation process combined with a cryogenic separation process for treating a gas stream containing methane, nitrogen and at least one other component. The membrane separation process works by preferentially permeating methane and the other component and rejecting nitrogen. The process is particularly useful in removing components such as water, carbon dioxide or C.sub.3+ hydrocarbons that might otherwise freeze and plug the cryogenic equipment.

  6. Methane-yielding microbial communities processing lactate-rich substrates: a piece of the anaerobic digestion puzzle.

    PubMed

    Detman, Anna; Mielecki, Damian; Pleśniak, Łukasz; Bucha, Michał; Janiga, Marek; Matyasik, Irena; Chojnacka, Aleksandra; Jędrysek, Mariusz-Orion; Błaszczyk, Mieczysław K; Sikora, Anna

    2018-01-01

    Anaerobic digestion, whose final products are methane and carbon dioxide, ensures energy flow and circulation of matter in ecosystems. This naturally occurring process is used for the production of renewable energy from biomass. Lactate, a common product of acidic fermentation, is a key intermediate in anaerobic digestion of biomass in the environment and biogas plants. Effective utilization of lactate has been observed in many experimental approaches used to study anaerobic digestion. Interestingly, anaerobic lactate oxidation and lactate oxidizers as a physiological group in methane-yielding microbial communities have not received enough attention in the context of the acetogenic step of anaerobic digestion. This study focuses on metabolic transformation of lactate during the acetogenic and methanogenic steps of anaerobic digestion in methane-yielding bioreactors. Methane-yielding microbial communities instead of pure cultures of acetate producers were used to process artificial lactate-rich media to methane and carbon dioxide in up-flow anaerobic sludge blanket reactors. The media imitated the mixture of acidic products found in anaerobic environments/digesters where lactate fermentation dominates in acidogenesis. Effective utilization of lactate and biogas production was observed. 16S rRNA profiling was used to examine the selected methane-yielding communities. Among Archaea present in the bioreactors, the order Methanosarcinales predominated. The acetoclastic pathway of methane formation was further confirmed by analysis of the stable carbon isotope composition of methane and carbon dioxide. The domain Bacteria was represented by Bacteroidetes , Firmicutes , Proteobacteria , Synergistetes , Actinobacteria , Spirochaetes , Tenericutes , Caldithrix , Verrucomicrobia , Thermotogae , Chloroflexi , Nitrospirae, and Cyanobacteria. Available genome sequences of species and/or genera identified in the microbial communities were searched for genes encoding the lactate-oxidizing metabolic machinery homologous to those of Acetobacterium woodii and Desulfovibrio vulgaris . Furthermore, genes for enzymes of the reductive acetyl-CoA pathway were present in the microbial communities. The results indicate that lactate is oxidized mainly to acetate during the acetogenic step of AD and this comprises the acetotrophic pathway of methanogenesis. The genes for lactate utilization under anaerobic conditions are widespread in the domain Bacteria. Lactate oxidation to the substrates for methanogens is the most energetically attractive process in comparison to butyrate, propionate, or ethanol oxidation.

  7. The social cost of methane: theory and applications.

    PubMed

    Shindell, D T; Fuglestvedt, J S; Collins, W J

    2017-08-24

    Methane emissions contribute to global warming, damage public health and reduce the yield of agricultural and forest ecosystems. Quantifying these damages to the planetary commons by calculating the social cost of methane (SCM) facilitates more comprehensive cost-benefit analyses of methane emissions control measures and is the first step to potentially incorporating them into the marketplace. Use of a broad measure of social welfare is also an attractive alternative or supplement to emission metrics focused on a temperature target in a given year as it incentivizes action to provide benefits over a broader range of impacts and timescales. Calculating the SCM using consistent temporal treatment of physical and economic processes and incorporating climate- and air quality-related impacts, we find large SCM values, e.g. ∼$2400 per ton and ∼$3600 per ton with 5% and 3% discount rates respectively. These values are ∼100 and 50 times greater than corresponding social costs for carbon dioxide. Our results suggest that ∼110 of 140 Mt of identified methane abatement via scaling up existing technology and policy options provide societal benefits that outweigh implementation costs. Within the energy sector, renewables compare far better against use of natural gas in electricity generation when incorporating these social costs for methane. In the agricultural sector, changes in livestock management practices, promoting healthy diets including reduced beef and dairy consumption, and reductions in food waste have been promoted as ways to mitigate emissions, and these are shown here to indeed have the potential to provide large societal benefits (∼$50-150 billion per year). Examining recent trends in methane and carbon dioxide, we find that increases in methane emissions may have offset much of the societal benefits from a slowdown in the growth rate of carbon dioxide emissions. The results indicate that efforts to reduce methane emissions via policies spanning a wide range of technical, regulatory and behavioural options provide benefits at little or negative net cost. Recognition of the full SCM, which has typically been undervalued, may help catalyze actions to reduce emissions and thereby provide a broad set of societal benefits.

  8. Methane Occurrence in a Drinking Water Aquifer Before and During Natural Gas Production from the Marcellus Shale

    NASA Astrophysics Data System (ADS)

    Saiers, J. E.; Barth-Naftilan, E.

    2017-12-01

    More than 4,000 thousand wells have punctured aquifers of Pennsylvania's northern tier to siphon natural gas from the underlying Marcellus Shale. As drilling and hydraulic fracturing ramped up a decade ago, homeowner reports of well water contamination by methane and other contaminants began to emerge. Although made infrequently compared to the number of gas wells drilled, these reports were troubling and motivated our two-year, prospective study of groundwater quality within the Marcellus Shale Play. We installed multi-level sampling wells within a bedrock aquifer of a 25 km2 area that was targeted for shale gas development. These wells were sampled on a monthly basis before, during, and after seven shale gas wells were drilled, hydraulically fractured, and placed into production. The groundwater samples, together with surface water samples collected from nearby streams, were analyzed for hydrocarbons, trace metals, major ions, and the isotopic compositions of methane, ethane, water, strontium, and dissolved inorganic carbon. With regard to methane in particular, concentrations ranged from under 0.1 to over 60 mg/L, generally increased with aquifer depth, and, at some sites, exhibited considerable temporal variability. The isotopic composition of methane and hydrocarbon ratios also spanned a large range, suggesting that methane origins are diverse and, notably, shift on the time scale of this study. We will present inferences on factors governing methane occurrence across our study area by interpreting time-series data on methane concentrations and isotopic composition in context of local hydrologic variation, companion measurements of groundwater chemistry, and the known timing of key stages of natural gas extraction.

  9. Examining gas flux responses to restoration

    EPA Science Inventory

    Wetlands play an important role in the flux of gases such as carbon dioxide, methane, and nitrous oxide. Wetland ecosystems are characterized by slow decomposition and, often, high productivity, making them net sinks of carbon dioxide. However, under some conditions, such as ti...

  10. Method of carbon dioxide-free hydrogen production from hydrocarbon decomposition over metal salts

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

    Erlebacher, Jonah; Gaskey, Bernard

    A process to decompose methane into carbon (graphitic powder) and hydrogen (H.sub.2 gas) without secondary production of carbon dioxide, employing a cycle in which a secondary chemical is recycled and reused, is disclosed.

  11. Emissions of Volatile Organic Compounds from Oil and Gas Operations in Northeastern Oklahoma - Wintertime Ambient Air Studies from Three Consecutive Years

    NASA Astrophysics Data System (ADS)

    Ghosh, B.

    2017-12-01

    Volatile organic compounds (VOCs) are emitted into the atmosphere from a variety of sources including oil and gas (O&G) operations, vehicle exhausts, industrial processes, and biogenic sources. Understanding of emission sources and their air quality impact is crucial for effective environmental policymaking and its implementation. Three consecutive wintertime campaigns to study ambient air were conducted in Northeastern Oklahoma during February-March of 2015, 2016, and 2017. The goals of these campaigns were to study ambient VOCs in the region, estimate their air quality impact, and understand how the impact changes over a span of three years. This presentation highlights results from the 2017 campaign. In-situ measurements of methane, ethane, and CO were conducted by an Aerodyne Dual QCL Analyzer while ozone and NOx were measured using Teledyne monitors. In addition, 392 whole air samples were collected and non-methane hydrocarbons (NMHCs) in the samples were analyzed using GC-MS (Agilent). High levels of methane (> 8 ppm) were observed during the study. Correlation with ethane indicated that methane primarily originated from O&G operations with little biogenic contributions. Among NMHCs, C2-C5 alkanes were the most dominant with mean mixing ratios ranging from 0.9 to 6.8 ppb. Chemical tracers (propane, ethyne, CO) and isomeric ratios (iC5/nC5, Figure 1) identified oil and gas activity as the primary source of NMHCs. Photochemical age was calculated to estimate emission source composition. Ozone showed strong diurnal variation characteristic of photochemical production with a maximum mixing ratio of 58 ppb. The results from the 2017 study will be compared with results from studies in 20151 and 20162 and their significance on local air quality will be discussed. References Ghosh, B.; Volatile Organic Compound Emissions from Oil and Gas Production Sources: A Pilot Study in Northeastern Oklahoma; Poster presentation at AGU Fall Meeting; 2015; A11M-0249; (Link) Ghosh, B.; Hydrocarbon Emission from Oil and Gas Production Activity in Northeastern Oklahoma - Wintertime Measurements in 2015 and 2016; Oral Presentation at AGU Fall Meeting; 2016; A14A-08; (Link)

  12. Methane and Carbon Dioxide Concentrations and Fluxes in Amazon Floodplains

    NASA Astrophysics Data System (ADS)

    Melack, J. M.; MacIntyre, S.; Forsberg, B.; Barbosa, P.; Amaral, J. H.

    2016-12-01

    Field studies on the central Amazon floodplain in representative aquatic habitats (open water, flooded forests, floating macrophytes) combine measurements of methane and carbon dioxide concentrations and fluxes to the atmosphere over diel and seasonal times with deployment of meteorological sensors and high-resolution thermistors and dissolved oxygen sondes. A cavity ringdown spectrometer is used to determine gas concentrations, and floating chambers and bubble collectors are used to measure fluxes. To further understand fluxes, we measured turbulence as rate of dissipation of turbulent kinetic energy based on microstructure profiling. These results allow calculations of vertical mixing within the water column and of air-water exchanges using surface renewal models. Methane and carbon dioxide fluxes varied as a function of season, habitat and water depth. High CO2 fluxes at high water are related to high pCO2; low pCO2 levels at low water result from increased phytoplankton uptake. CO2 fluxes are highest at turbulent open water sites, and pCO2 is highest in macrophyte beds. Fluxes and pCH4 are high in macrophyte beds.

  13. 30 CFR 75.336 - Sampling and monitoring requirements.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... travel and where ventilation is used for escapeways. The operator's request shall also address the gas... specific levels of methane, carbon dioxide, nitrogen and oxygen; the sampling methods and equipment used... areas. Sealed areas shall be monitored, whether ingassing or outgassing, for methane and oxygen...

  14. 30 CFR 75.336 - Sampling and monitoring requirements.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... travel and where ventilation is used for escapeways. The operator's request shall also address the gas... specific levels of methane, carbon dioxide, nitrogen and oxygen; the sampling methods and equipment used... areas. Sealed areas shall be monitored, whether ingassing or outgassing, for methane and oxygen...

  15. 30 CFR 75.336 - Sampling and monitoring requirements.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... travel and where ventilation is used for escapeways. The operator's request shall also address the gas... specific levels of methane, carbon dioxide, nitrogen and oxygen; the sampling methods and equipment used... areas. Sealed areas shall be monitored, whether ingassing or outgassing, for methane and oxygen...

  16. A Heuristic Approach to Examining Volatile Equilibrium at Titan's Surface

    NASA Technical Reports Server (NTRS)

    Samuelson, Robert E.

    1999-01-01

    R. D. Lorenz, J. I. Lunine, and C. P. McKay have shown in a manuscript accepted for publication that, for a given ethane abundance and surface temperature, the nitrogen and methane abundances in Titan's atmosphere can be calculated, yielding a surface pressure that can be compared with the observed value. This is potentially a very valuable tool for examining the evolution of Titan's climatology. Its validity does depend on two important assumptions, however: 1) that the atmosphere of Titan is in global radiative equilibrium, and 2) that volatiles present are in vapor equilibrium with the surface. The former assumption has been shown to be likely, but the latter has not. Water vapor in the Earth's atmosphere, in fact, is generally not very close to equilibrium in a global sense. In the present work a heuristic approach is used to examine the likelihood that methane vapor is in equilibrium with Titan's surface. Plausible climate scenerios are examined that are consistent with methane vapor abundances derived from Voyager IRIS data. Simple precipitation and surface diffusion models are incorporated into the analysis. It is tentatively inferred that methane may be in surface equilibrium near the poles, but that equilibrium at low latitudes is more difficult to establish.

  17. Evaluation of Sorbents for Acetylene Separation in Atmosphere Revitalization Loop Closure

    NASA Technical Reports Server (NTRS)

    Abney, Morgan B.; Miller, Lee A.; Barton, Katherine

    2012-01-01

    State-of-the-art carbon dioxide reduction technology uses a Sabatier reactor to recover water from metabolic carbon dioxide. In order to maximize oxygen loop closure, a byproduct of the system, methane, must be reduced to recover hydrogen. NASA is currently exploring a microwave plasma methane pyrolysis system for this purpose. The resulting product stream of this technology includes unreacted methane, product hydrogen, and acetylene. The hydrogen and the small amount of unreacted methane resulting from the pyrolysis process can be returned to the Sabatier reactor thereby substantially improving the overall efficiency of the system. However, the acetylene is a waste product that must be removed from the pyrolysis product. Two materials have been identified as potential sorbents for acetylene removal: zeolite 4A, a commonly available commercial sorbent, and HKUST-1, a newly developed microporous metal. This paper provides an explanation of the rationale behind acetylene removal and the results of separation testing with both materials

  18. Evaluation of Sorbents for Acetylene Separation in Atmosphere Revitalization Loop Closure

    NASA Technical Reports Server (NTRS)

    Abney, Morgan B.; Miller, Lee A.; Barton, Katherine

    2011-01-01

    State-of-the-art carbon dioxide reduction technology uses a Sabatier reactor to recover water from metabolic carbon dioxide. In order to maximize oxygen loop closure, a byproduct of the system, methane, must be reduced to recover hydrogen. NASA is currently exploring a microwave plasma methane pyrolysis system for this purpose. The resulting product stream of this technology includes unreacted methane, product hydrogen, and acetylene. The hydrogen and the small amount of unreacted methane resulting from the pyrolysis process can be returned to the Sabatier reactor thereby substantially improving the overall efficiency of the system. However, the acetylene is a waste product that must be removed from the pyrolysis product. Two materials have been identified as potential sorbents for acetylene removal: zeolite 4A, a commonly available commercial sorbent, and HKUST-1, a newly developed microporous metal. This paper provides an explanation of the rationale behind acetylene removal and the results of separation testing with both materials.

  19. Radiative forcing of carbon dioxide, methane, and nitrous oxide: A significant revision of the methane radiative forcing

    NASA Astrophysics Data System (ADS)

    Etminan, M.; Myhre, G.; Highwood, E. J.; Shine, K. P.

    2016-12-01

    New calculations of the radiative forcing (RF) are presented for the three main well-mixed greenhouse gases, methane, nitrous oxide, and carbon dioxide. Methane's RF is particularly impacted because of the inclusion of the shortwave forcing; the 1750-2011 RF is about 25% higher (increasing from 0.48 W m-2 to 0.61 W m-2) compared to the value in the Intergovernmental Panel on Climate Change (IPCC) 2013 assessment; the 100 year global warming potential is 14% higher than the IPCC value. We present new simplified expressions to calculate RF. Unlike previous expressions used by IPCC, the new ones include the overlap between CO2 and N2O; for N2O forcing, the CO2 overlap can be as important as the CH4 overlap. The 1750-2011 CO2 RF is within 1% of IPCC's value but is about 10% higher when CO2 amounts reach 2000 ppm, a value projected to be possible under the extended RCP8.5 scenario.

  20. Solar hydrogen production: renewable hydrogen production by dry fuel reforming

    NASA Astrophysics Data System (ADS)

    Bakos, Jamie; Miyamoto, Henry K.

    2006-09-01

    SHEC LABS - Solar Hydrogen Energy Corporation constructed a pilot-plant to demonstrate a Dry Fuel Reforming (DFR) system that is heated primarily by sunlight focusing-mirrors. The pilot-plant consists of: 1) a solar mirror array and solar concentrator and shutter system; and 2) two thermo-catalytic reactors to convert Methane, Carbon Dioxide, and Water into Hydrogen. Results from the pilot study show that solar Hydrogen generation is feasible and cost-competitive with traditional Hydrogen production. More than 95% of Hydrogen commercially produced today is by the Steam Methane Reformation (SMR) of natural gas, a process that liberates Carbon Dioxide to the atmosphere. The SMR process provides a net energy loss of 30 to 35% when converting from Methane to Hydrogen. Solar Hydrogen production provides a 14% net energy gain when converting Methane into Hydrogen since the energy used to drive the process is from the sun. The environmental benefits of generating Hydrogen using renewable energy include significant greenhouse gas and criteria air contaminant reductions.

  1. Carbon Dioxide Reduction Systems

    NASA Technical Reports Server (NTRS)

    Burghardt, Stanley I.; Chandler, Horace W.; Taylor, T. I.; Walden, George

    1961-01-01

    The Methoxy system for regenerating oxygen from carbon dioxide was studied. Experiments indicate that the reaction between carbon dioxide and hydrogen can be carried out with ease in an efficient manner and with excellent heat conservation. A small reactor capable of handling the C02 expired by three men has been built and operated. The decomposition of methane by therma1,arc and catalytic processes was studied. Both the arc and catalytic processes gave encouraging results with over 90 percent of the methane being decomposed to carbon and hydrogen in some of the catalytic processes. Control of the carbon deposition in both the catalytic and arc processes is of great importance to prevent catalyst deactivation and short circuiting of electrical equipment. Sensitive analytical techniques have been developed for all of the components present in the reactor effluent streams.

  2. Surrogate Indicators of Radionuclide Migration at the Amargosa Desert Research Site, Nye County, Nevada

    NASA Astrophysics Data System (ADS)

    Stonestrom, D. A.; Andraski, B. J.; Baker, R. J.; Luo, W.; Michel, R. L.

    2005-05-01

    Contaminant-transport processes are being investigated at the U.S. Geological Survey's Amargosa Desert Research Site (ADRS), adjacent to the Nation's first commercial disposal facility for low-level radioactive waste. Gases containing tritium and radiocarbon are migrating through a 110-m thick unsaturated zone from unlined trenches that received waste from 1962 to 1992. Information on plume dynamics comes from an array of shallow (<2 m) and two vertical arrays of deep (5-109 m) gas-sampling ports, plus ground-water monitoring wells. Migration is dominated by lateral transport in the upper 50 m of sediments. Radiological analyses require ex-situ wet-chemical techniques, because in-situ sensors for the radionuclides of interest do not exist. As at other LLRW-disposal facilities, radionuclides at the ADRS are mixed with varying amounts of volatile organic compounds (VOCs) and other substances. Halogenated-methanes, -ethanes, and -ethenes dominate the complex mixture of VOCs migrating from the disposal area. These compounds and their degradates provide a distinctive "fingerprint" of contamination originating from low-level radioactive waste. Carbon-dioxide and VOC anomalies provide indicator proxies for radionuclide contamination. Spatial and temporal patterns of co-disposed and byproduct constituents provide field-scale information about physical and biochemical processes involved in transport. Processes include reduction and biorespiration within trenches, and largely non-reactive, barometrically dispersed diffusion away from trenches.

  3. Analysis of exhaled breath by laser detection

    NASA Astrophysics Data System (ADS)

    Thrall, Karla D.; Toth, James J.; Sharpe, Steven W.

    1996-04-01

    The goal of our work is two fold: (1) to develop a portable rapid laser based breath analyzer for monitoring metabolic processes, and (2) predict these metabolic processes through physiologically based pharmacokinetic (PBPK) modeling. Small infrared active molecules such as ammonia, carbon monoxide, carbon dioxide, methane and ethane are present in exhaled breath and can be readily detected by laser absorption spectroscopy. In addition, many of the stable isotopomers of these molecules can be accurately detected, making it possible to follow specific metabolic processes. Potential areas of applications for this technology include the diagnosis of certain pathologies (e.g. Helicobacter Pylori infection), detection of trauma due to either physical or chemical causes and monitoring nutrient uptake (i.e., malnutrition). In order to understand the origin and elucidate the metabolic processes associated with these small molecules, we are employing physiologically based pharmacokinetic (PBPK) models. A PBPK model is founded on known physiological processes (i.e., blood flow rates, tissue volumes, breathing rate, etc.), chemical-specific processes (i.e., tissue solubility coefficients, molecular weight, chemical density, etc.), and on metabolic processes (tissue site and rate of metabolic biotransformation). Since many of these processes are well understood, a PBPK model can be developed and validated against the more readily available experimental animal data, and then by extrapolating the parameters to apply to man, the model can predict chemical behavior in humans.

  4. Electron Irradiation of Kuiper Belt Surface Ices: Ternary N2-CH4-CO Mixtures as a Case Study

    NASA Astrophysics Data System (ADS)

    Kim, Y. S.; Kaiser, R. I.

    2012-10-01

    The space weathering of icy Kuiper Belt Objects was investigated in this case study by exposing methane (CH4) and carbon monoxide (CO) doped nitrogen (N2) ices at 10 K to ionizing radiation in the form of energetic electrons. Online and in situ Fourier transform infrared spectroscopy was utilized to monitor the radiation-induced chemical processing of these ices. Along with isocyanic acid (HNCO), the products could be mainly derived from those formed in irradiated binary ices of the N2-CH4 and CO-CH4 systems: nitrogen-bearing products were found in the form of hydrogen cyanide (HCN), hydrogen isocyanide (HNC), diazomethane (CH2N2), and its radical fragment (HCN2); oxygen-bearing products were of acetaldehyde (CH3CHO), formyl radical (HCO), and formaldehyde (H2CO). As in the pure ices, the methyl radical (CH3) and ethane (C2H6) were also detected, as were carbon dioxide (CO2) and the azide radical (N3). Based on the temporal evolution of the newly formed products, kinetic reaction schemes were then developed to fit the temporal profiles of the newly formed species, resulting in numerical sets of rate constants. The current study highlights important constraints on the preferential formation of isocyanic acid (HNCO) over hydrogen cyanide (HCN) and hydrogen isocyanide (HNC), thus guiding the astrobiological and chemical evolution of those distant bodies.

  5. Using a Network of Flux Towers to Investigate the Effects of Wetland Restoration on Greenhouse Gas Fluxes

    NASA Astrophysics Data System (ADS)

    Baldocchi, D. D.; Hatala, J.; Knox, S.; Verfaillie, J. G.; Anderson, F.

    2012-12-01

    The Sacramento-San Joaquin Delta, a peatland and former wetland, was drained a 100 years ago for intensive agriculture. In the interim, over 10 m of peat has been lost, mostly through oxidation. Current land use is not sustainable, if this region is to maintain its integrity and serve as a conduit for freshwater pumped from northern to southern California. There is great interest in restoring this disturbed landscape with tule wetlands or rice; one is an effective carbon sink, the other an economically viable alternative. Questions arise to how effective are these new landscapes in sequestering carbon and what are the unintended consequences, such as the production of methane and high rates of evaporation from flooded lands, in a semi-arid climate? We are currently operating 6 eddy covariance flux systems that measure short and long term fluxes of carbon dioxide, water vapor and methane. We are making flux measurements over landscapes that represent business as usual (irrigated pasture and corn) and new alternatives (rice, a newly restored wetland and a 14 year old wetland). The pasture and corn operate as carbon sources and are weak emitters of methane on annual time scales. The rice is a modest sink of carbon dioxide, but becomes a carbon source when harvesting is considered. It is a smaller source of methane compared to rice growing in the Sacramento Valley on clay. It seems that there are sufficient alternative electron acceptors (iron, nitrate) that moderate methane production for rice growing on peat soils. The newly restored wetland is a huge methane source, with fluxes exceeding 300 nmol m-2 s-1. In the first two years of functioning, following disturbance, it is switching from being a carbon source to a sink, as tules fill the landscape. The older wetland remains a strong methane source, and its carbon dioxide sink potential is diminishing at it becomes derelict with much undecomposed vegetation.

  6. 75 FR 53883 - Action To Ensure Authority To Issue Permits Under the Prevention of Significant Deterioration...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-09-02

    ... long-lived and directly emitted GHGs--carbon dioxide (CO 2 ), methane (CH 4 ), nitrous oxide (N 2 O... carbon dioxide equivalent (CO 2 e) but only if the project also significantly increase emissions of at... emissions must be calculated on both a mass basis and, as alluded to above, a carbon dioxide equivalent (CO...

  7. Global Analysis, Interpretation, and Modelling: First Science Conference

    NASA Technical Reports Server (NTRS)

    Sahagian, Dork

    1995-01-01

    Topics considered include: Biomass of termites and their emissions of methane and carbon dioxide - A global database; Carbon isotope discrimination during photosynthesis and the isotope ratio of respired CO2 in boreal forest ecosystems; Estimation of methane emission from rice paddies in mainland China; Climate and nitrogen controls on the geography and timescales of terrestrial biogeochemical cycling; Potential role of vegetation feedback in the climate sensitivity of high-latitude regions - A case study at 6000 years B.P.; Interannual variation of carbon exchange fluxes in terrestrial ecosystems; and Variations in modeled atmospheric transport of carbon dioxide and the consequences for CO2 inversions.

  8. Membrane-augmented cryogenic methane/nitrogen separation

    DOEpatents

    Lokhandwala, K.

    1997-07-15

    A membrane separation process is described which is combined with a cryogenic separation process for treating a gas stream containing methane, nitrogen and at least one other component. The membrane separation process works by preferentially permeating methane and the other component and rejecting nitrogen. The process is particularly useful in removing components such as water, carbon dioxide or C{sub +2} hydrocarbons that might otherwise freeze and plug the cryogenic equipment. 10 figs.

  9. Gas hydrates and active mud volcanism on the South Shetland continental margin, Antarctic Peninsula

    NASA Astrophysics Data System (ADS)

    Tinivella, U.; Accaino, F.; Della Vedova, B.

    2008-04-01

    During the Antarctic summer of 2003 2004, new geophysical data were acquired from aboard the R/V OGS Explora in the BSR-rich area discovered in 1996 1997 along the South Shetland continental margin off the Antarctic Peninsula. The objective of the research program, supported by the Italian National Antarctic Program (PNRA), was to verify the existence of a potential gas hydrate reservoir and to reconstruct the tectonic setting of the margin, which probably controls the extent and character of the diffused and discontinuous bottom simulating reflections. The new dataset, i.e. multibeam bathymetry, seismic profiles (airgun and chirp), and two gravity cores analysed by computer-aided tomography as well as for gas composition and content, clearly shows active mud volcanism sustained by hydrocarbon venting in the region: several vents, located mainly close to mud volcanoes, were imaged during the cruise and their occurrence identified in the sediment samples. Mud volcanoes, vents and recent slides border the gas hydrate reservoir discovered in 1996 1997. The cores are composed of stiff silty mud. In core GC01, collected in the proximity of a mud volcano ridge, the following gases were identified (maximum contents in brackets): methane (46 μg/kg), pentane (45), ethane (35), propane (34), hexane (29) and butane (28). In core GC02, collected on the flank of the Vualt mud volcano, the corresponding data are methane (0 μg/kg), pentane (45), ethane (22), propane (0), hexane (27) and butane (25).

  10. Fatal methane and cyanide poisoning as a result of handling industrial fish: a case report and review of the literature

    PubMed Central

    Cherian, M; Richmond, I

    2000-01-01

    The potential health hazards of handling industrial fish are well documented. Wet fish in storage consume oxygen and produce poisonous gases as they spoil. In addition to oxygen depletion, various noxious agents have been demonstrated in association with spoilage including carbon dioxide, sulphur dioxide, and ammonia. A fatal case of methane and cyanide poisoning among a group of deep sea trawler men is described. Subsequent independent investigation as a result of this case led to the discovery of cyanides as a further potential noxious agent. This is thus the first case in which cyanide poisoning has been recognised as a potentially fatal complication of handling spoiled fish. The previous literature is reviewed and the implications of the current case are discussed. Key Words: industrial fish • methane • cyanide PMID:11064677

  11. Results of coalbed-methane drilling, Mylan Park, Monongalia County, West Virginia: Chapter G.3 in Coal and petroleum resources in the Appalachian basin: distribution, geologic framework, and geochemical character

    USGS Publications Warehouse

    Ruppert, Leslie F.; Fedorko, Nick; Warwick, Peter D.; Grady, William C.; Britton, James Q.; Schuller, William A.; Crangle, Robert D.; Ruppert, Leslie F.; Ryder, Robert T.

    2014-01-01

    High-pressure carbon-dioxide adsorption isotherms were measured on composite coal samples of the Upper Kittanning coal bed and the Middle Kittanning and Clarion coal zones. Assuming that the reservoir pressure in the Mylan Park coals is equivalent to the normal hydrostatic pressure, the estimated maximum carbon-dioxide adsorption pressures range from a low of about 300 pounds per square inch (lb/in2 ) in coals from the Clarion coal zone to 500 lb/in2 for coals from the Upper Kittanning coal bed. The estimated maximum methane adsorption isotherms show that the coals from the Upper Kittanning coal bed and the Middle Kittanning coal zone are undersaturated in methane, but coals from the Clarion coal zone are close to saturation.

  12. High-precision optical measurements of 13C/12C isotope ratios in organic compounds at natural abundance

    PubMed Central

    Zare, Richard N.; Kuramoto, Douglas S.; Haase, Christa; Tan, Sze M.; Crosson, Eric R.; Saad, Nabil M. R.

    2009-01-01

    A continuous-flow cavity ring-down spectroscopy (CRDS) system integrating a chromatographic separation technique, a catalytic combustor, and an isotopic 13C/12C optical analyzer is described for the isotopic analysis of a mixture of organic compounds. A demonstration of its potential is made for the geochemically important class of short-chain hydrocarbons. The system proved to be linear over a 3-fold injection volume dynamic range with an average precision of 0.95‰ and 0.67‰ for ethane and propane, respectively. The calibrated accuracy for methane, ethane, and propane is within 3‰ of the values determined using isotope ratio mass spectrometry (IRMS), which is the current method of choice for compound-specific isotope analysis. With anticipated improvements, the low-cost, portable, and easy-to-use CRDS-based instrumental setup is poised to evolve into a credible challenge to the high-cost and complex IRMS-based technique. PMID:19564619

  13. The Effects of Surface Properties and Albedo on Methane Retrievals with the Airborne Visible/Infrared Imaging Spectrometer Next Generation (AVIRIS-NG)

    NASA Astrophysics Data System (ADS)

    Ayasse, A.; Thorpe, A. K.; Roberts, D. A.

    2017-12-01

    Atmospheric methane has increased by a factor of 2.5 since the beginning of the industrial era in response to anthropogenic emissions (Ciais et al., 2013). Although it is less abundant than carbon dioxide it is 86 time more potent on a 20 year time scale (Myhre et al., 2013) and is therefore responsible for about 20% of the total global warming induced by anthropogenic greenhouse gasses (Kirschke et al., 2013). Given the importance of methane to global climate change, monitoring and measuring methane emissions using techniques such as remote sensing is of increasing interest. Recently the Airborne Visible-Infrared Imaging Spectrometer - Next Generation (AVIRIS-NG) has proven to be a valuable instrument for quantitative mapping of methane plumes (Frankenberg et al., 2016; Thorpe et al., 2016; Thompson et al., 2015). In this study, we applied the Iterative Maximum a Posterior Differential Optical Spectroscopy (IMAP-DOAS) methane retrieval algorithm to a synthetic image with variable methane concentrations, albedo, and land cover. This allowed for characterizing retrieval performance, including potential sensitivity to variable land cover, low albedo surfaces, and surfaces known to cause spurious signals. We conclude that albedo had little influence on the IMAP-DOAS results except at very low radiance levels. Water (without sun glint) was found to be the most challenging surface for methane retrievals while hydrocarbons and some green vegetation also caused error. Understanding the effect of surface properties on methane retrievals is important given the increased use of AVIRIS-NG to map gas plumes over diverse locations and methane sources. This analysis could be expanded to include additional gas species like carbon dioxide and to further investigate gas sensitivity of proposed instruments for dedicated gas mapping from airborne and spaceborne platforms.

  14. Role of microorganisms for cycling of atmospheric constituents, emphasizing the greenhouse gas methane (Invited)

    NASA Astrophysics Data System (ADS)

    Conrad, R.

    2013-12-01

    Microorganisms have contributed significantly to the formation of the atmosphere and the habitability of Earth. Microbial methanogenesis probably helped overcoming the faint sun problem on young Earth. Later on, cyanobacterial photosynthesis produced oxygen and thus restricted the life zone of methanogenic microbial communities, which nowadays contribute only about 1% to total carbon cycle. Nevertheless, methanogenesis still dominates the budget of atmospheric methane and contributes significantly to the greenhouse effect. There are numerous habitats, which exchange methane with the atmosphere, and even more in which methane is intensively cycled albeit little emitted. Methane can be a byproduct of chemical reactions in plant leaves, or of aerobic methyl phosphonate consumption in ocean water. Most commonly, however, methane is a stoichiometric catabolic product in the degradation of organic matter by anaerobic microorganisms. The degradation is achieved by a complex microbial community consisting of various species of hydrolytic and fermentative Bacteria that produce hydrogen, carbon dioxide and acetate as major end products, and of methanogenic Archaea that eventually convert these compounds to methane and carbon dioxide. The composition of such methanogenic microbial communities, the rates and paths of methane formation, and the isotopic composition of the produced methane all exhibit quite some variability across the different habitats in which methane is produced from organic matter decomposition, such as flooded soils, lake sediments, peatlands, animal gut systems. The structure of the microbial communities often strongly affects their function. It is a challenging task to understand the environmental and biochemical basis of the interactions of abiotic factors and microorganisms shaping the structure and function of the microbial communities in the different methanogenic habitats.

  15. Effect of various gases (methane, CO/sub 2/) on root development and/or mycorrhizae production on Virginia pine. [Pinus virginiana; Amanita rubescens

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

    Russo, V.M.; Klarman, W.L.

    1975-01-01

    Various flow rates of air, air containing methane, and air containing carbon dioxide were passed through sterile, nutrient-saturated sand in one-liter flasks. Sixteen-day-old axenic seedlings of Pinus virginiana were planted either prior to or immediately following treatment of medium. Some flasks were also inoculated with Amanita rubescens, a fungus commonly mycorrhizal with P. virginiana. Seedlings were maintained under continuous illumination for 30 days at 24 C and roots were then examined to determine development and/or mycorrhizal association. Dry weights of roots and whole seedlings were measured. Root development of seedlings planted in medium prior to treatment with air increased withmore » increase of flow-rate to 1.25 liters per hour. When treated with methane or carbon-dioxide fewer seedlings with developed root systems were produced. Seedlings planted in medium colonized by A. rubescens and treated with air or air containing carbon-dioxide produced increasing numbers of developed roots as flow rate increased, but other seedlings treated with methane produced fewer developed roots with increase in flow-rate. Mycorrhizal production was maximum at flow-rates between 0.25 and 0.6 liters. Generally fewer developed roots and/or mycorrhizae were produced by seedlings planted in treated medium than on similar seedlings planted before gas treatment. Dry weights generally paralleled root development.« less

  16. 40 CFR 86.1327-96 - Engine dynamometer test procedures; overview.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... hydrocarbons, carbon monoxide, oxides of nitrogen, particulate, methanol and formaldehyde, as applicable. The... either in bags or continuously for hydrocarbons (HC), methane (CH4) carbon monoxide (CO), carbon dioxide... levels of hydrocarbon, carbon monoxide, carbon dioxide, and oxides of nitrogen and, if appropriate...

  17. 40 CFR 86.1327-96 - Engine dynamometer test procedures; overview.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... hydrocarbons, carbon monoxide, oxides of nitrogen, particulate, methanol and formaldehyde, as applicable. The... either in bags or continuously for hydrocarbons (HC), methane (CH4) carbon monoxide (CO), carbon dioxide... levels of hydrocarbon, carbon monoxide, carbon dioxide, and oxides of nitrogen and, if appropriate...

  18. 40 CFR 86.1327-96 - Engine dynamometer test procedures; overview.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... either in bags or continuously for hydrocarbons (HC), methane (CH4) carbon monoxide (CO), carbon dioxide..., methane and/or methanol and/or formaldehyde. In addition, for diesel-cycle engines, particulates are... if typical of the in-use application. (5) The engine may be equipped with a production-type starter...

  19. 40 CFR 86.1327-96 - Engine dynamometer test procedures; overview.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... either in bags or continuously for hydrocarbons (HC), methane (CH4) carbon monoxide (CO), carbon dioxide..., methane and/or methanol and/or formaldehyde. In addition, for diesel-cycle engines, particulates are... if typical of the in-use application. (5) The engine may be equipped with a production-type starter...

  20. Fire and Pesticides: A Review of Air Quality Considerations

    Treesearch

    Parshall B. Bush; Daniel G. Neary; Charles K. McMahon

    2000-01-01

    The classes of primary chemical products naturally produced by the combustion of forest fuels are: carbon dioxide, water, carbon monoxide, particulate matter, methane and non-methane hydrocarbons, polynuclear aromatic hydrocarbons, nitrogen and sulfur oxides, aldehydes, free radicals, and inorganic elements. Secondary chemical products produced by reactions in smoke...

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