Flux and distribution of methane (CH4) in the Gunsan Basin of the southeastern Yellow Sea, off the Western Korea.

Science.gov (United States)

Lee, Jun-Ho; Woo, Han Jun; Son, Seung-Kyu; Kim, Moonkoo; Lee, Dong-Hun; Tsunogai, Urumu; Jeong, Kap-Sik

2018-04-16

The flux and distribution of methane (CH 4 ) was investigated in the seawater column at 14 stations in the Gunsan Basin, the southeastern part of Yellow Sea from 2013 to 2015. Here CH 4 is concentrated 2.4-4.7 (3.4 ± 0.7) nM in the surface and 2.5-7.4 (5.2 ± 1.7) nM in the bottom layer. The CH 4 saturation ratios ranged from 65.5% to 295.5% (162.6 ± 68.7), comprising the mean sea-to-air CH 4 flux of 3.8 to 25.3 (15.6 ± 5.5) µM m -2 d -1 . Methane concentration was largely different in the upper and the lower seawater layers that is separated by the thermocline of which depth is variable (20-60 m) depending on the time of sampling. The concentration of seawater dissolved CH 4 is high between the bottom surface of the thermocline layer and the sea floor. Generally it tends to decrease from the south-westernmost part of the basin toward the west coast of Korea. This distribution pattern of CH 4 seems to result from the CH 4 supply by decomposition of organic matters produced in the upper seawater layer that is superimposed by the larger supply from the underlying sediment layer especially beneath the thermocline. The latter is manifested by ubiquitous CH 4 seeps from the seafloor sediments.

Optical sensor system for time-resolved quantification of methane densities in CH4-fueled spark ignition engines.

Science.gov (United States)

Golibrzuch, Kai; Digulla, Finn-Erik; Bauke, Stephan; Wackerbarth, Hainer; Thiele, Olaf; Berg, Thomas

2017-08-01

We present the development and the first application of an optical sensor system that allows single-cycle determination of methane (CH 4 ) concentration inside internal combustion (IC) engines. We use non-dispersive infrared absorption spectroscopy to detect the CH 4 density with a time resolution up to 33 μs at acquisition rates of 30 kHz. The measurement scheme takes advantage of the strong temperature dependence of the absorption band applying two detection channels for CH 4 that detect different spectral regions of the ν 3 anti-symmetric C-H-stretch absorption. The strategy allows the simultaneous determination of fuel concentration as well as gas temperature. We show the proof-of-concept by validation of the measurement strategy in static pressure cell experiments as well as its application to a methane-fueled IC engine using a modified spark plug probe. Our results clearly demonstrate that it is crucial to determine the CH 4 temperature in the probe volume. Due to thermal influences of the sensor probe, the temperature needed to calculate the desired quantities (fuel density, fuel concentration) significantly differs from the gas phase temperature in the rest of the combustion chamber and estimations from standard thermodynamic models, e.g., polytropic compression, will fail.

Identifying sources of methane sampled in the Arctic using δ13C in CH4 and Lagrangian particle dispersion modelling.

Science.gov (United States)

Cain, Michelle; France, James; Pyle, John; Warwick, Nicola; Fisher, Rebecca; Lowry, Dave; Allen, Grant; O'Shea, Sebastian; Illingworth, Samuel; Jones, Ben; Gallagher, Martin; Welpott, Axel; Muller, Jennifer; Bauguitte, Stephane; George, Charles; Hayman, Garry; Manning, Alistair; Myhre, Catherine Lund; Lanoisellé, Mathias; Nisbet, Euan

2016-04-01

An airmass of enhanced methane was sampled during a research flight at ~600 m to ~2000 m altitude between the North coast of Norway and Svalbard on 21 July 2012. The largest source of methane in the summertime Arctic is wetland emissions. Did this enhancement in methane come from wetland emissions? The airmass was identified through continuous methane measurements using a Los Gatos fast greenhouse gas analyser on board the UK's BAe-146 Atmospheric Research Aircraft (ARA) as part of the MAMM (Methane in the Arctic: Measurements and Modelling) campaign. A Lagrangian particle dispersion model (the UK Met Office's NAME model) was run backwards to identify potential methane source regions. This was combined with a methane emission inventory to create "pseudo observations" to compare with the aircraft observations. This modelling was used to constrain the δ13C CH4 wetland source signature (where δ13C CH4 is the ratio of 13C to 12C in methane), resulting in a most likely signature of -73‰ (±4‰7‰). The NAME back trajectories suggest a methane source region of north-western Russian wetlands, and -73‰ is consistent with in situ measurements of wetland methane at similar latitudes in Scandinavia. This analysis has allowed us to study emissions from remote regions for which we do not have in situ observations, giving us an extra tool in the determination of the isotopic source variation of global methane emissions.

Methane Provenance Determined by CH2D2 and 13CH3D Abundances

Science.gov (United States)

Kohl, I. E.; Giunta, T.; Warr, O.; Ash, J. L.; Ruffine, L.; Sherwood Lollar, B.; Young, E. D.

2017-12-01

Determining the provenance of naturally occurring methane gases is of major interest to energy companies and atmospheric climate modelers, among others. Bulk isotopic compositions and other geochemical tracers sometimes fail to provide definitive determinations of sources of methane due to complications from mixing and complicated chemical pathways of origin. Recent measurements of doubly-substituted isotopologues of methane, CH2D2 (UCLA) and 13CH3D (UCLA, CalTech, and MIT) have allowed for major improvements in sourcing natural methane gases. Early work has focused on formation temperatures obtained when the relative abundances of both doubly-substituted mass-18 species are consistent with internal equilibrium. When methane gases do not plot on the thermodynamic equilibrium curve in D12CH2D2 vs D13CH3D space, temperatures determined from D13CH3D values alone are usually spurious, even when appearing reasonable. We find that the equilibrium case is actually rare and almost exclusive to thermogenic gases produced at temperatures exceeding 100°C. All other relevant methane production processes appear to generate gases that are not in isotopologue-temperature equilibrium. When gases show departures from equilibrium as determined by the relationship between CH2D2 and 13CH3D abundances, data fall within empirically defined fields representing formation pathways. These fields are thus far consistent between different geological settings and and between lab experiments and natural samples. We have now defined fields for thermogenic gas production, microbial methanogenesis, low temperature abiotic (Sabatier) synthesis and higher temperature FTT synthesis. The majority of our natural methane data can be explained by mixing between end members originating within these production fields. Mixing can appear complex, resulting in both hyper-clumped and anti-clumped isotopologue abundances. In systems where mixtures dominate and end-members are difficult to sample, mixing models

Concurrent enrichment in δD and δ13C in CH4 within stems of aquatic plants relative to methane within sediments

International Nuclear Information System (INIS)

Chanton, J.P.; Showers, W.J.

1991-01-01

13 CH 4 enrichment in methane within the stems of aquatic macrophytes relative to methane held within the sediments has been demonstrated previously. Hypotheses offered to explain this phenomenon include methane oxidation, production and transport effects (Chanton et al., Geophys. Res. Lett. 16, 799, 1989). The authors report here concurrent enrichment of δD and δ 13 C ranging from 36-59 per-thousand and 5.8-11.5 per-thousand respectively for methane within stems relative to methane within the sediments in a stand of Pontederia cordata. This sympathetic variation of H and C isotopes serves to eliminate the production hypothesis as an explanation of the effects observed. If production effects were responsible for the 13 CH 4 enrichment within macrophyte stems, H and C isotopes would have been expected to vary antipathetically (Whiticar et al., Geochim. Cosmochim. Acta, 50, 693, 1986)

Biological Production of Methane from Lunar Mission Solid Waste: An Initial Feasibility Assessment

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Strayer, Richard; Garland, Jay; Janine, Captain

are commercially available, and cost, the main limitation to terrestrial use, is not an issue for the small-scale, specialty use by NASA. If the plastic content of the lunar mission solid waste stream is biodegradable, then a potential yield of methane from the waste can be estimated. Investigators at the placePlaceTypeUniversity of PlaceNameFlorida have reported on a three-stage anaerobic composting system for treatment of solid wastes expected in an Advanced Life Support System for space surface habitation. Their system, a sequential batch anaerobic composter (SEBAC) has been demonstrated for a variety of terrestrial solid wastes. Results for methane production rate from a simulated stocktickerALS solid waste of inedible rice crop debris, paper, and simulated feces averaged 0.30 L CH4 per gdw volatile solids (VS, i.e., organic matter) added. If we extrapolate from their results and assume that the VS in space mission solid waste is 100% biodegradable, then a potential for 620 LCH4 crew-1 d-1 might be obtained with a comparable SEBAC. For a crew of four, 2480 LCH4 d-1 (or 110.7 molesCH4 d-1 , 1772 gCH4 d-1 , or 3.90 lbCH4 d-1 )., would be produced. Over a 180 day surface habitation, this generation rate would yield a total of 446,000 LCH4 (319 kgCH4 , 702 lbCH4 ). The next step in this effort is to estimate the costs of biological processing system required to convert the solid waste steam to methane. We will employ equivalent system mass (ESM) analysis to define the costs of the system in terms of energy, mass, and manpower required for processing, allowing for a better estimation of the net benefit of this in situ resource utilization approach.

A Year in the Life: Annual Patterns of CO2 and CH4 from a Northern Finland Peatland, Including Anaerobic Methane Oxidation and Summer Ebullition Rates

Science.gov (United States)

Miller, K.; Lipson, D.; Biasi, C.; Dorodnikov, M.; Männistö, M.; Lai, C. T.

2014-12-01

The major ecological controls on methane (CH4) and carbon dioxide (CO2) fluxes in northern wetland systems are well known, yet estimates of source/sink magnitudes are often incongruous with measured rates. This mismatch persists because holistic flux datasets are rare, preventing 'whole picture' determinations of flux controls. To combat this, we measured net CO2 and CH4 fluxes from September 2012-2013 within a peatland in northern Lapland, Finland. In addition, we performed in situ manipulations and in vitro soil incubations to quantify anaerobic methane oxidation and methanogenic rates as they related to alternative electron acceptor availability. Average annual fluxes varied substantially between different depressions within the wetland, a pattern that persisted through all seasons. Season was a strong predictor of both CO2 and CH4 flux rates, yet CH4 rates were not related to melt-season 10cm or 30cm soil temperatures, and only poorly predicted with air temperatures. We found evidence for both autumnal and spring thaw CH4 bursts, collectively accounting for 26% of annual CH4 flux, although the autumnal burst was more than 5 fold larger than the spring burst. CH4 ebullition measured throughout the growing season augmented the CH4 source load by a factor of 1.5, and was linked with fine-scale spatial heterogeneity within the wetland. Surprisingly, CH4 flux rates were insensitive to Fe(III) and humic acid soil amendments, both of which amplified CO2 fluxes. Using in vitro incubations, we determined anaerobic methane oxidation and methanogenesis rates. Measured anaerobic oxidation rates showed potential consumption of between 6-39% of the methane produced, contributing approximately 1% of total carbon dioxide flux. Treatments of nitrate, sulfate and ferric iron showed that nitrate suppressed methanogenesis, but were not associated with anaerobic oxidation rates.

Megafauna and frozen soil: the drivers of atmospheric CH4 dynamics

Science.gov (United States)

Zimov, N.; Zimov, S. A.

2010-12-01

During the last deglaciation (LD) a strong increase in atmospheric methane (CH4) concentrations occurred simultaneously with a rise in Greenland temperatures indicating that in the north, during this time period, strong CH4 sources “awakened”, as additionally documented by the appearance of a strong gradient between northern (Greenland) and southern (Antarctica) hemisphere atmospheric CH4 concentrations. This rise could not be caused by wetland expansion. A reconstruction of peatland formation dynamics has indicated that wetlands on Earth were few in LD and only actively expanded 10,000 yr BP, after atmospheric CH4 concentrations began to decline. Destabilization of methane clathrates also could not be the source for atmospheric CH4 increase. Geological CH4 (including methane clathrates) has the highest deuterium content (δD) among all of the known sources of CH4 while atmospheric CH4 δD values determined for the LD were record low. To explain recorded atmospheric CH4 and its isotopic dynamics required a strong northern source, which was active only during the LD and that provided very low δD CH4 values. Such a source is permafrost thawing under anaerobic conditions (or better stated soils of mammoth steppe-tundra ecosystems). Permafrost thawing is the strongest, among known, wetland sources (usually over 100g CH4/m2yr) and has a unique isotopic signature (δD = -400 per mil (-338 to -479 per mil), δ13C = -73 per mil (-58 to -99 per mil)). The main sources of atmospheric CH4 have different isotopic signatures (δ13C, δD). The isotopic content of atmospheric CH4 is a simple function of the weight average for all of the sources. Inclusion of permafrost source into a budget model of the atmospheric methane and its isotopes allowed us to reconstruct the dynamics of methane’s main sources. Model indicated geological source to be negligible as in LGM so and in LD and Holocene. During the glaciation, the largest methane source was megafauna, whose 1.4

On the methane paradox: Transport from shallow water zones rather than in situ methanogenesis is the major source of CH4 in the open surface water of lakes

Science.gov (United States)

Encinas Fernández, Jorge; Peeters, Frank; Hofmann, Hilmar

2016-10-01

Estimates of global methane (CH4) emissions from lakes and the contributions of different pathways are currently under debate. In situ methanogenesis linked to algae growth was recently suggested to be the major source of CH4 fluxes from aquatic systems. However, based on our very large data set on CH4 distributions within lakes, we demonstrate here that methane-enriched water from shallow water zones is the most likely source of the basin-wide mean CH4 concentrations in the surface water of lakes. Consistently, the mean surface CH4 concentrations are significantly correlated with the ratio between the surface area of the shallow water zone and the entire lake, fA,s/t, but not with the total surface area. The categorization of CH4 fluxes according to fA,s/t may therefore improve global estimates of CH4 emissions from lakes. Furthermore, CH4 concentrations increase substantially with water temperature, indicating that seasonally resolved data are required to accurately estimate annual CH4 emissions.

Spectrally-resolved UV photodesorption of CH4 in pure and layered ices

Science.gov (United States)

Dupuy, R.; Bertin, M.; Féraud, G.; Michaut, X.; Jeseck, P.; Doronin, M.; Philippe, L.; Romanzin, C.; Fillion, J.-H.

2017-07-01

Context. Methane is among the main components of the ice mantles of interstellar dust grains, where it is at the start of a rich solid-phase chemical network. Quantification of the photon-induced desorption yield of these frozen molecules and understanding of the underlying processes is necessary to accurately model the observations and the chemical evolution of various regions of the interstellar medium. Aims: This study aims at experimentally determining absolute photodesorption yields for the CH4 molecule as a function of photon energy. The influence of the ice composition is also investigated. By studying the methane desorption from layered CH4:CO ice, indirect desorption processes triggered by the excitation of the CO molecules are monitored and quantified. Methods: Tunable monochromatic vacuum ultraviolet light (VUV) light from the DESIRS beamline of the SOLEIL synchrotron is used in the 7-13.6 eV (177-91 nm) range to irradiate pure CH4 or layers of CH4 deposited on top of CO ice samples. The release of species in the gas phase is monitored by quadrupole mass spectrometry, and absolute photodesorption yields of intact CH4 are deduced. Results: CH4 photodesorbs for photon energies higher than 9.1 eV ( 136 nm). The photodesorption spectrum follows the absorption spectrum of CH4, which confirms a desorption mechanism mediated by electronic transitions in the ice. When it is deposited on top of CO, CH4 desorbs between 8 and 9 eV with a pattern characteristic of CO absorption, indicating desorption induced by energy transfer from CO molecules. Conclusions: The photodesorption of CH4 from pure ice in various interstellar environments is around 2.0 ± 1.0 × 10-3 molecules per incident photon. Results on CO-induced indirect desorption of CH4 provide useful insights for the generalization of this process to other molecules co-existing with CO in ice mantles.

Pig feeding strategy coupled with effluent management - fresh or stored slurry, solid phase separation - on methane potential and methane conversion factors during storage

Science.gov (United States)

Jarret, Guillaume; Martinez, José; Dourmad, Jean-Yves

2011-11-01

In the guideline for the determination of methane (CH 4) emission from animal manure (IPCC) the amount of CH 4 emitted is generally calculated according to an equation combining the amount of organic matter (OM) or volatile solids excreted, the ultimate CH 4 potential ( B0) of excreta and a system-specific methane conversion factor (MCF, %) that reflects the portion of B0 that is really converted into CH 4. The objective of the present study was to investigate the effect of the modification of dietary crude protein and fibre levels on B0 of pig slurry and on subsequent MCF according to different strategies of slurry management. Five experimental diets differing mainly in their crude protein and fibre content were compared. Two types of measurement of CH 4 emission were performed. The first was the measurement of B0 of slurry using biomethanogene potential (BMP) test. The second consisted in a storage simulation, which was performed on different kinds of effluents: fresh slurry (FSl), stored slurry (SSl), and faeces mixed with water (FaW). The type of diet and the type of effluent affected ( P storage from FaW, FSl and SSl samples representing 77%, 58% and 64% of the B0 value. The dynamic of CH 4 production during BMP tests was rather similar for all dietary treatments whereas it differed for storage simulation studies with significant effects of dietary CP and fibre contents. The results from this study indicate that the type of diet has a significant but rather limited effect on B0 value of effluent. The effect of diet is much more marked on MCF, with lower values for high protein diets, and higher values for high fibre diets. MCF is also affected by manure management, the values measured on separated faeces from urine being much higher than for slurry.

Improving accuracy and precision of ice core δD(CH4 analyses using methane pre-pyrolysis and hydrogen post-pyrolysis trapping and subsequent chromatographic separation

Directory of Open Access Journals (Sweden)

M. Bock

2014-07-01

Full Text Available Firn and polar ice cores offer the only direct palaeoatmospheric archive. Analyses of past greenhouse gas concentrations and their isotopic compositions in air bubbles in the ice can help to constrain changes in global biogeochemical cycles in the past. For the analysis of the hydrogen isotopic composition of methane (δD(CH4 or δ2H(CH4 0.5 to 1.5 kg of ice was hitherto used. Here we present a method to improve precision and reduce the sample amount for δD(CH4 measurements in (ice core air. Pre-concentrated methane is focused in front of a high temperature oven (pre-pyrolysis trapping, and molecular hydrogen formed by pyrolysis is trapped afterwards (post-pyrolysis trapping, both on a carbon-PLOT capillary at −196 °C. Argon, oxygen, nitrogen, carbon monoxide, unpyrolysed methane and krypton are trapped together with H2 and must be separated using a second short, cooled chromatographic column to ensure accurate results. Pre- and post-pyrolysis trapping largely removes the isotopic fractionation induced during chromatographic separation and results in a narrow peak in the mass spectrometer. Air standards can be measured with a precision better than 1‰. For polar ice samples from glacial periods, we estimate a precision of 2.3‰ for 350 g of ice (or roughly 30 mL – at standard temperature and pressure (STP – of air with 350 ppb of methane. This corresponds to recent tropospheric air samples (about 1900 ppb CH4 of about 6 mL (STP or about 500 pmol of pure CH4.

Steam Methane Reformation Testing for Air-Independent Solid Oxide Fuel Cell Systems

Science.gov (United States)

Mwara, Kamwana N.

2015-01-01

Recently, NASA has been looking into utilizing landers that can be propelled by LOX-CH (sub 4), to be used for long duration missions. Using landers that utilize such propellants, also provides the opportunity to use solid oxide fuel cells as a power option, especially since they are able to process methane into a reactant through fuel reformation. One type of reformation, called steam methane reformation, is a process to reform methane into a hydrogen-rich product by reacting methane and steam (fuel cell exhaust) over a catalyst. A steam methane reformation system could potentially use the fuel cell's own exhaust to create a reactant stream that is hydrogen-rich, and requires less internal reforming of the incoming methane. Also, steam reformation may hold some advantages over other types of reforming, such as partial oxidation (PROX) reformation. Steam reformation does not require oxygen, while up to 25 percent can be lost in PROX reformation due to unusable CO (sub 2) reformation. NASA's Johnson Space Center has conducted various phases of steam methane reformation testing, as a viable solution for in-space reformation. This has included using two different types of catalysts, developing a custom reformer, and optimizing the test system to find the optimal performance parameters and operating conditions.

Phase transitions in solid Kr-CH4 solutions and rotational excitations in phase II

International Nuclear Information System (INIS)

Bagatskii, M.I.; Mashchenko, D.A.; Dudkin, V.V.

2007-01-01

The heat capacity C p of solid Kr-n CH 4 solutions with the CH 4 concentrations n=0.82, 0.86, 0.90 as well as solutions with n=0.90, 0.95 doped with 0.002 O 2 impurity has been investigated under equilibrium vapor pressure over the internal 1-24 K. The (T,n)-phase diagram was refined and the region of two-phase states was determined for Kr-n CH 4 solid solutions. The contribution of the rotational subsystem, C r ot, to the heat capacity of the solutions has been separated. Analysis of C r ot(T) at T 1 and E 2 between the tunnel levels of the A-, T- and A-, E--nuclear-spin species of CH 4 molecules in the orientationally ordered subsystem, and to determine the effective energy gaps E 1 between lowest levels of the A- and T- species. The relations τ(n) and E 1 (n) stem from changes of the effective potential field caused as the replacement of CH 4 molecules by Kr atoms at sites of the ordered sublattices. The effective gaps E L between a group of tunnel levels of the ground-state liberation state and the nearest group of excited levels of the liberation state of the ordered CH 4 molecules in the solutions with n=0.90 (E L =52 K) and 0.95 (E L =55 K) has been estimated

Quantifying the relative contribution of natural gas fugitive emissions to total methane emissions in Weld County Colorado using δ13CH4 analysis

Science.gov (United States)

Rella, C.; Jacobson, G. A.; Crosson, E.; Sweeney, C.; Karion, A.; Petron, G.

2012-12-01

Fugitive emissions of methane into the atmosphere are a major concern facing the natural gas production industry. Given that the global warming potential of methane is many times greater than that of carbon dioxide (Forster et al. 2007), the importance of quantifying methane emissions becomes clear. Companion presentations at this meeting describe efforts to quantify the overall methane emissions in two separate gas producing areas in Colorado and Utah during intensive field campaigns undertaken in 2012. A key step in the process of assessing the emissions arising from natural gas production activities is partitioning the observed methane emissions between natural gas fugitive emissions and other sources of methane, such as from landfills or agricultural activities. One method for assessing the contribution of these different sources is stable isotope analysis. In particular, the δ13CH4 signature of natural gas (-37 permil) is significantly different that the signature of other significant sources of methane, such as landfills or ruminants (-50 to -70 permil). In this paper we present measurements of δ13CH4 in Colorado in Weld County, a region of intense natural gas production, using a mobile δ13CH4¬ analyzer capable of high-precision measurements of the stable isotope ratio of methane at ambient levels. This analyzer was used to make stable isotope measurements at a fixed location near the center of the gas producing region, from which an overall isotope ratio for the regional emissions is determined. In addition, mobile measurements in the nocturnal boundary layer have been made, over a total distance of 150 km throughout Weld County, allowing spatially resolved measurements of this isotope signature. Finally, this analyzer was used to quantify the isotopic signature of those individual sources (natural gas fugitive emissions, concentrated animal feeding operations, and landfills) that constitute the majority of methane emissions in this region, by making

A 4 U Laser Heterodyne Radiometer for Methane (CH4) and Carbon Dioxide (CO2) Measurements from an Occultation-Viewing CubSat

Science.gov (United States)

Wilson, Emily L.; DiGregorio, A. J.; Riot, Vincent J.; Ammons, Mark S.; Bruner, WIlliam W.; Carter, Darrell; Mao, Jianping; Ramanathan, Anand; Strahan, Susan E.; Oman, Luke D.;

New materials for methane capture from dilute and medium-concentration sources

Energy Technology Data Exchange (ETDEWEB)

Kim, J; Maiti, A; Lin, LC; Stolaroff, JK; Smit, B; Aines, RD

2013-04-16

Methane (CH4) is an important greenhouse gas, second only to CO2, and is emitted into the atmosphere at different concentrations from a variety of sources. However, unlike CO2, which has a quadrupole moment and can be captured both physically and chemically in a variety of solvents and porous solids, methane is completely non-polar and interacts very weakly with most materials. Thus, methane capture poses a challenge that can only be addressed through extensive material screening and ingenious molecular-level designs. Here we report systematic in silico studies on the methane capture effectiveness of two different materials systems, that is, liquid solvents (including ionic liquids) and nanoporous zeolites. Although none of the liquid solvents appears effective as methane sorbents, systematic screening of over 87,000 zeolite structures led to the discovery of a handful of candidates that have sufficient methane sorption capacity as well as appropriate CH4/CO2 and/or CH4/N-2 selectivity to be technologically promising.

Methane production from fermentation of winery waste

Energy Technology Data Exchange (ETDEWEB)

Lo, K V; Liao, P H

1986-01-01

A laboratory-scale reactor receiving a mixture of screened dairy manure and winery waste was studied at 35 degrees C and a hydraulic retention time of 4 days. The maximum methane production rate of 8.14 liter CH/sub 4//liter/day was achieved at a loading rate of 7.78 g VS/liter/day (VS = volatile solids). The corresponding methane yield was 1.048 liter CH/sub 4//g VS added. Using a mixture of winery wastes and screened dairy manure as the feed material to anaerobic reactor resulted in a significant increase in total methane production compared to that from screened dairy manure alone. The biodegradation efficiency increased with the addition of winery wastes to screened dairy manure. 18 references.

Methane emission from ruminants and solid waste: A critical analysis of baseline and mitigation projections for climate and policy studies

Science.gov (United States)

Matthews, E.

2012-12-01

Current and projected estimates of methane (CH4) emission from anthropogenic sources are numerous but largely unexamined or compared. Presented here is a critical appraisal of CH4 projections used in climate-chemistry and policy studies. We compare emissions for major CH4 sources from several groups, including our own new data and RCP projections developed for climate-chemistry models for the next IPCC Assessment Report (AR5). We focus on current and projected baseline and mitigation emissions from ruminant animals and solid waste that are both predicted to rise dramatically in coming decades, driven primarily by developing countries. For waste, drivers include increasing urban populations, higher per capita waste generation due to economic growth and increasing landfilling rates. Analysis of a new global data base detailing waste composition, collection and disposal indicates that IPCC-based methodologies and default data overestimate CH4 emission for the current period which cascades into substantial overestimates in future projections. CH4 emission from solid waste is estimated to be ~10-15 Tg CH4/yr currently rather than the ~35 Tg/yr often reported in the literature. Moreover, emissions from developing countries are unlikely to rise rapidly in coming decades because new management approaches, such as sanitary landfills, that would increase emissions are maladapted to infrastructures in these countries and therefore unlikely to be implemented. The low current emission associated with solid waste (~10 Tg), together with future modest growth, implies that mitigation of waste-related CH4 emission is a poor candidate for slowing global warming. In the case of ruminant animals (~90 Tg CH4/yr currently), the dominant assumption driving future trajectories of CH4 emission is a substantial increase in meat and dairy consumption in developing countries to be satisfied by growing animal populations. Unlike solid waste, current ruminant emissions among studies exhibit a

Linking rhizospheric CH₄ oxidation and net CH₄ emissions in an arctic wetland based on ¹³CH₄ labeling of mesocosms

DEFF Research Database (Denmark)

Nielsen, Cecilie Skov; Michelsen, Anders; Ambus, Per

2017-01-01

Aims: Poorly drained arctic ecosystems are potential large emitters of methane (CH4) due to their high soil organic carbon content and low oxygen availability. In wetlands, aerenchymatous plants transport CH4 from the soil to the atmosphere, but concurrently transport O2 to the rhizosphere, which...... may lead to oxidation of CH4. The importance of the latter process is largely unknown for arctic plant species and ecosystems. Here, we aim to quantify the subsurface oxidation of CH4 in a waterlogged arctic ecosystem dominated by Carex aquatilis ssp. stans and Eriophorum angustifolium, and evaluate...... during three weeks after addition of 13C-enriched CH4 below the mesocosm. Results: Most of the recovered 13C label (>98 %) escaped the ecosystem as CH4, while less than 2 % was oxidized to 13CO2. Conclusions: It is concluded that aerenchymatous plants control the overall CH4 emissions but, as a transport...

A 4 U laser heterodyne radiometer for methane (CH4) and carbon dioxide (CO2) measurements from an occultation-viewing CubeSat

International Nuclear Information System (INIS)

Wilson, Emily L; Oman, Luke D; DiGregorio, A J; Garner, Richard M; Riot, Vincent J; Ammons, Mark S; Bruner, William W; Carter, Darrell; Mao, Jianping; Ramanathan, Anand; Strahan, Susan E; Hoffman, Christine

2017-01-01

We present a design for a 4 U (20 cm  ×  20 cm  ×  10 cm) occultation-viewing laser heterodyne radiometer (LHR) that measures methane (CH 4 ), carbon dioxide (CO 2 ) and water vapor (H 2 O) in the limb that is designed for deployment on a 6 U CubeSat. The LHR design collects sunlight that has undergone absorption by the trace gas and mixes it with a distributive feedback (DFB) laser centered at 1640 nm that scans across CO 2 , CH 4 , and H 2 O absorption features. Upper troposphere/lower stratosphere measurements of these gases provide key inputs to stratospheric circulation models: measuring stratospheric circulation and its variability is essential for projecting how climate change will affect stratospheric ozone. (paper)

A 4 U laser heterodyne radiometer for methane (CH4) and carbon dioxide (CO2) measurements from an occultation-viewing CubeSat

Science.gov (United States)

Wilson, Emily L.; DiGregorio, A. J.; Riot, Vincent J.; Ammons, Mark S.; Bruner, William W.; Carter, Darrell; Mao, Jianping; Ramanathan, Anand; Strahan, Susan E.; Oman, Luke D.; Hoffman, Christine; Garner, Richard M.

2017-03-01

We present a design for a 4 U (20 cm  ×  20 cm  ×  10 cm) occultation-viewing laser heterodyne radiometer (LHR) that measures methane (CH4), carbon dioxide (CO2) and water vapor (H2O) in the limb that is designed for deployment on a 6 U CubeSat. The LHR design collects sunlight that has undergone absorption by the trace gas and mixes it with a distributive feedback (DFB) laser centered at 1640 nm that scans across CO2, CH4, and H2O absorption features. Upper troposphere/lower stratosphere measurements of these gases provide key inputs to stratospheric circulation models: measuring stratospheric circulation and its variability is essential for projecting how climate change will affect stratospheric ozone.

Implications of Representative Concentration Pathway 4.5 Methane Emissions to Stabilize Radiative Forcing

Energy Technology Data Exchange (ETDEWEB)

Emanuel, William R.; Janetos, Anthony C.

2013-02-01

Increases in the abundance of methane (CH4) in the Earth’s atmosphere are responsible for significant radiative forcing of climate change (Forster et al., 2007; Wuebbles and Hayhoe, 2002). Since 1750, a 2.5 fold increase in atmospheric CH4 contributed 0.5 W/m2 to direct radiative forcing and an additional 0.2 W/m2 indirectly through changes in atmospheric chemistry. Next to water and carbon dioxide (CO2), methane is the most abundant greenhouse gas in the troposphere. Additionally, CH4 is significantly more effective as a greenhouse gas on a per molecule basis than is CO2, and increasing atmospheric CH4 has been second only to CO2 in radiative forcing (Forster et al., 2007). The chemical reactivity of CH4 is important to both tropospheric and stratospheric chemistry. Along with carbon monoxide, methane helps control the amount of the hydroxyl radical (OH) in the troposphere where oxidation of CH4 by OH leads to the formation of formaldehyde, carbon monoxide, and ozone.

Windrow composting mitigated CH4 emissions: characterization of methanogenic and methanotrophic communities in manure management.

Science.gov (United States)

Chen, Ruirui; Wang, Yiming; Wei, Shiping; Wang, Wei; Lin, Xiangui

2014-12-01

With increasing livestock breeding, methane (CH4 ) emissions from manure management will increasingly contribute more to atmospheric CH4 concentration. The dynamics of methanogens and methanotrophs have not yet been studied in the manure environment. The current study combines surface CH4 emissions with methanogenic and methanotrophic community analyses from two management practices, windrow composting (WCOM) and solid storage (SSTO). Our results showed that there was an c. 50% reduction of CH4 emissions with WCOM compared with SSTO over a 50-day period. A sharp decrease in the quantities of both methanogens and methanotrophs in WCOM suggested that CH4 mitigation was mainly due to decreased CH4 production rather than increased CH4 oxidation. Pyrosequencing analysis demonstrated that aeration caused a clear shift of dominant methanogens in the manure, with specifically a significant decrease in Methanosarcina and increase in Methanobrevibacter. The composition of methanogenic community was influenced by manure management and regulated CH4 production. A sharp increase in the quantity of methanotrophs in SSTO suggested that microbial CH4 oxidation is an important sink for the CH4 produced. The increased abundance of Methylococcaceae in SSTO suggested that Type I methanotrophs have an advantage in CH4 oxidation in occupying niches under low CH4 and high O2 conditions. © 2014 Federation of European Microbiological Societies. Published by John Wiley & Sons Ltd. All rights reserved.

Composite hydrogen-solid methane moderators

International Nuclear Information System (INIS)

Picton, D.; Bennington, S.; Ansell, S.; Fernandez-Garcia, J.; Broome, T.

2004-01-01

This paper describes the results of Monte-Carlo calculations for a coupled moderator on a low-power pulsed neutron spallation source and is part of the design study for a second target station for the ISIS spallation source. Various options were compared including hydrogen, solid methane, grooving the solid methane and compound moderators made of hydrogen in front of solid methane. To maximise the neutron current at low energies two strategies appear to emerge from the calculations. For instruments that view a large area of moderator surface a layer of hydrogen in front of a thin solid-methane moderator is optimum, giving a gain of about a factor 10 relative to the current liquid hydrogen moderator on the existing ISIS tantalum target. For instruments that only view a restricted area higher flux, corresponding to a gain of 13.5, can be achieved with the use of a single groove or re-entrant hole in the moderator. (orig.)

Screening boreal energy crops and crop residues for methane biofuel production

Energy Technology Data Exchange (ETDEWEB)

Lehtomaeki, A.; Rintala, J.A. [Department of Biological and Environmental Science, University of Jyvaeskylae, P.O. Box 35, FI-40014 Jyvaeskylae (Finland); Viinikainen, T.A. [Department of Chemistry, University of Jyvaeskylae, P.O. Box 35, FI-40014 Jyvaeskylae (Finland)

2008-06-15

The purpose of the study was to screen potential boreal energy crops and crop residues for their suitability in methane production and to investigate the effect of harvest time on the methane production potential of different crops. The specific methane yields of crops, determined in 100-200 d methane potential assays, varied from 0.17 to 0.49 m{sup 3} CH{sub 4} kg{sup -1} VS{sub added} (volatile solids added) and from 25 to 260 m{sup 3} CH{sub 4} t{sub ww}{sup -1} (tonnes of wet weight). Jerusalem artichoke, timothy-clover grass and reed canary grass gave the highest potential methane yields of 2900-5400 m{sup 3} CH{sub 4} ha{sup -1}, corresponding to a gross energy yield of 28-53 MWh ha{sup -1} and ca. 40,000-60,000 km ha{sup -1} in passenger car transport. The effect of harvest time on specific methane yields per VS of crops varied a lot, whereas the specific methane yields per t{sub ww} increased with most crops as the crops matured. (author)

Tropospheric radiative forcing of CH4

International Nuclear Information System (INIS)

Grossman, A.S.; Grant, K.E.

1994-04-01

We have evaluated the tropospheric radiative forcing of CH 4 in the 0-3000 cm -1 wavenumber range and compared this with prior published calculations. The atmospheric test cases involved perturbed methane scenarios in both a McClatchey mid latitude, summer, clear sky approximation, model atmosphere, as well as a globally and seasonally averaged model atmosphere containing a representative cloud distribution. The scenarios involved pure CH 4 radiative forcing and CH 4 plus a mixture of H 2 O, CO 2 , O 3 , and N 2 O. The IR radiative forcing was calculated using a correlated k-distribution transmission model. The major purposes of this paper are to first, use the correlated k-distribution model to calculate the tropospheric radiative forcing for CH 4 , as the only radiatively active gas, and in a mixture with H 2 O, CO 2 , O 3 , and N 2 O, for a McClatchey mid-latitude summer, clear-sky model atmosphere, and to compare the results to those obtained in the studies mentioned above. Second, we will calculate the tropospheric methane forcing in a globally and annually averaged atmosphere with and without a representative cloud distribution in order to validate the conjecture given in IPCC (1990) that the inclusion of clouds in the forcing calculations results in forcing values which are approximately 20 percent less than those obtained using clear sky approximations

New accurate theoretical line lists of 12CH4 and 13CH4 in the 0-13400 cm-1 range: Application to the modeling of methane absorption in Titan's atmosphere

Science.gov (United States)

Rey, Michaël; Nikitin, Andrei V.; Bézard, Bruno; Rannou, Pascal; Coustenis, Athena; Tyuterev, Vladimir G.

2018-03-01

The spectrum of methane is very important for the analysis and modeling of Titan's atmosphere but its insufficient knowledge in the near infrared, with the absence of reliable absorption coefficients, is an important limitation. In order to help the astronomer community for analyzing high-quality spectra, we report in the present work the first accurate theoretical methane line lists (T = 50-350 K) of 12CH4 and 13CH4 up to 13400 cm-1 ( > 0.75 μm). These lists are built from extensive variational calculations using our recent ab initio potential and dipole moment surfaces and will be freely accessible via the TheoReTS information system (http://theorets.univ-reims.fr, http://theorets.tsu.ru). Validation of these lists is presented throughout the present paper. For the sample of lines where upper energies were available from published analyses of experimental laboratory 12CH4 spectra, small empirical corrections in positions were introduced that could be useful for future high-resolution applications. We finally apply the TheoRetS line list to model Titan spectra as observed by VIMS and by DISR, respectively onboard Cassini and Huygens. These data are used to check that the TheoReTS line lists are able to model observations. We also make comparisons with other experimental or theoretical line lists. It appears that TheoRetS gives very reliable results better than ExoMol and even than HITRAN2012, except around 1.6 μm where it gives very similar results. We conclude that TheoReTS is suitable to be used for the modeling of planetary radiative transfer and photometry. A re-analysis of spectra recorded by the DISR instrument during the descent of the Huygens probe suggests that the CH4 mixing ratio decreases with altitude in Titan's stratosphere, reaching a value of ∼10-2 above the 110 km altitude.

Co-Digestion of Napier Grass and Its Silage with Cow Dung for Methane Production

Directory of Open Access Journals (Sweden)

Wipa Prapinagsorn

2017-10-01

Full Text Available Methane production from co-digestion of grass with cow dung and silage with cow dung was conducted by a bioaugmentation technique. For self-fermentation, maximum methane yield (MY of 176.66 and 184.94 mL CH4/g-VSadded were achieved at a ratio of grass to cow dung and silage to cow dung of 1:1, respectively. A higher maximum MY of 179.59 and 208.11 mL CH4/g-VSadded was obtained from co-digestion of grass with cow dung and silage with cow dung bioaugmented with anaerobic sludge at a ratio of 3:1. The solid residue left over after co-digestion at a ratio of 3:1 was pretreated by alkaline plus enzyme before used to produce methane and a maximum MY of 333.63 and 301.38 mL CH4/g-VSadded, respectively, was achieved. Overall power generated from co-digestion of grass with cow dung plus pretreated solid residues and co-digestion of silage with cow dung plus pretreated solid residues were 0.0397 and 0.007 watt, respectively.

Gully hotspot contribution to landscape methane (CH4) and carbon dioxide (CO2) fluxes in a northern peatland

International Nuclear Information System (INIS)

McNamara, N.P.; Plant, T.; Oakley, S.; Ward, S.; Wood, C.; Ostle, N.

2008-01-01

Peatlands are long term carbon catchments that sink atmospheric carbon dioxide (CO 2 ) and source methane (CH 4 ). In the uplands of the United Kingdom ombrotrophic blanket peatlands commonly exist within Calluna vulgaris (L.) dominated moorland ecosystems. These landscapes contain a range of topographical features that influence local hydrology, climate and plant community composition. In this study we examined the variation in ecosystem CO 2 respiration and net CH 4 fluxes from typical plant-soil systems in dendritic drainage gullies and adjacent blanket peat during the growing season. Typically, Eriophorum spp., Sphagnum spp. and mixed grasses occupied gullies while C. vulgaris dominated in adjacent blanket peat. Gross CO 2 respiration was highest in the areas of Eriophorum spp. (650 ± 140 mg CO 2 m -2 h -1 ) compared to those with Sphagnum spp. (338 ± 49 mg CO 2 m -2 h -1 ), mixed grasses (342 ± 91 mg CO 2 m -2 h -1 ) and C. vulgaris (174 ± 63 mg CO 2 m -2 h -1 ). Measurements of the net CH 4 flux showed higher fluxes from the Eriophorum spp (2.2 ± 0.6 mg CH 4 m -2 h -1 ) locations compared to the Sphagnum spp. (0.6 ± 0.4 mg CH 4 m -2 h -1 ), mixed grasses (0.1 ±0.1 mg CH 4 m -2 h -1 ) and a negligible flux detected from C. vulgaris (0.0 ± 0.0 mg CH 4 m -2 h -1 ) locations. A GIS approach was applied to calculate the contribution of gullies to landscape scale greenhouse gas fluxes. Findings from the Moor House National Nature Reserve in the UK showed that although gullies occupied only 9.3% of the total land surface, gullies accounted for 95.8% and 21.6% of the peatland net CH 4 and CO 2 respiratory fluxes, respectively. The implication of these findings is that the relative contribution of characteristic gully systems need to be considered in estimates of landscape scale peatland greenhouse gas fluxes

How to oxidize atmospheric CH4? - A challenge for the future

International Nuclear Information System (INIS)

Chazelas, Bruno; Leger, Alain; Ollivier, Marc

2006-01-01

Methane is an active Greenhouse effect gas whose concentration will likely increase in the future. The possible destabilisation of CH 4 clathrates (hydrates) due to anthropogenic climate warming, and the resulting outgasing of methane, could lead to a major increase of the global Greenhouse effect, with dramatic consequences for Humanity. For these reasons, the study of possible countermeasures should be actively considered. Here, we suggest taking advantage of the thermodynamic instability of CH 4 in air, and search for ways to oxidize it

The H2/CH4 ratio during serpentinization cannot reliably identify biological signatures.

Science.gov (United States)

Huang, Ruifang; Sun, Weidong; Liu, Jinzhong; Ding, Xing; Peng, Shaobang; Zhan, Wenhuan

2016-09-26

Serpentinization potentially contributes to the origin and evolution of life during early history of the Earth. Serpentinization produces molecular hydrogen (H 2 ) that can be utilized by microorganisms to gain metabolic energy. Methane can be formed through reactions between molecular hydrogen and oxidized carbon (e.g., carbon dioxide) or through biotic processes. A simple criterion, the H 2 /CH 4 ratio, has been proposed to differentiate abiotic from biotic methane, with values approximately larger than 40 for abiotic methane and values of serpentinization experiments at 200 °C and 0.3 kbar. However, it is not clear whether the criterion is applicable at a wider range of temperatures. In this study, we performed sixteen experiments at 311-500 °C and 3.0 kbar using natural ground peridotite. Our results demonstrate that the H 2 /CH 4 ratios strongly depend on temperature. At 311 °C and 3.0 kbar, the H 2 /CH 4 ratios ranged from 58 to 2,120, much greater than the critical value of 40. By contrast, at 400-500 °C, the H 2 /CH 4 ratios were much lower, ranging from 0.1 to 8.2. The results of this study suggest that the H 2 /CH 4 ratios cannot reliably discriminate abiotic from biotic methane.

The H2/CH4 ratio during serpentinization cannot reliably identify biological signatures

Science.gov (United States)

Huang, Ruifang; Sun, Weidong; Liu, Jinzhong; Ding, Xing; Peng, Shaobang; Zhan, Wenhuan

2016-09-01

Serpentinization potentially contributes to the origin and evolution of life during early history of the Earth. Serpentinization produces molecular hydrogen (H2) that can be utilized by microorganisms to gain metabolic energy. Methane can be formed through reactions between molecular hydrogen and oxidized carbon (e.g., carbon dioxide) or through biotic processes. A simple criterion, the H2/CH4 ratio, has been proposed to differentiate abiotic from biotic methane, with values approximately larger than 40 for abiotic methane and values of serpentinization experiments at 200 °C and 0.3 kbar. However, it is not clear whether the criterion is applicable at a wider range of temperatures. In this study, we performed sixteen experiments at 311-500 °C and 3.0 kbar using natural ground peridotite. Our results demonstrate that the H2/CH4 ratios strongly depend on temperature. At 311 °C and 3.0 kbar, the H2/CH4 ratios ranged from 58 to 2,120, much greater than the critical value of 40. By contrast, at 400-500 °C, the H2/CH4 ratios were much lower, ranging from 0.1 to 8.2. The results of this study suggest that the H2/CH4 ratios cannot reliably discriminate abiotic from biotic methane.

IPNS grooved, solid methane moderator

International Nuclear Information System (INIS)

Carpenter, J.M.; Schulke, A.W.; Scott, T.L.; Wozniak, D.G.; Benson, B.E.; Leyda, B.D.

1985-01-01

There are two motives for using cold moderators in pulsed neutron sources, to provide higher fluxes of long-wavelength neutrons, and to extend the epithermal range with its short pulse structure to lower energies. For both these purposes solid methane, operated at the lowest possible temperatures, is the best material we know of. Two problems accompany the use of solid methane in high power sources, namely heat transport in view of the low thermal conductivity of solid methane, and deterioration due to radiation damage. We have designed a system suitable to operate in IPNS, subject to nuclear heating of about 25 W, which incorporates an aluminum foam matrix to conduct the heat from within the moderator. We report the results of the first few months' operation and of a few tests that we have performed

CH4 emissions from European Major Population Centers: Results from aircraft-borne CH4 in-situ observations during EMeRGe-Europe campaign 2017

Science.gov (United States)

Roiger, A.; Klausner, T.; Schlager, H.; Ziereis, H.; Huntrieser, H.; Baumann, R.; Eirenschmalz, L.; Joeckel, P.; Mertens, M.; Fisher, R.; Bauguitte, S.; Young, S.; Andrés Hernández, M. D.

2017-12-01

Urban environments represent large and diffuse area sources of CH4 including emissions from pipeline leaks, industrial/sewage treatment plants, and landfills. However, there is little knowledge about the exact magnitude of these emissions and their contribution to total anthropogenic CH4. Especially in the context of an urbanizing world, a better understanding of the methane footprint of urban areas is crucial, both with respect to mitigation and projection of climate impacts. Aircraft-borne in-situ measurements are particularly useful to both quantify emissions from such area sources, as well as to study their impact on the regional distribution. However, airborne CH4 observations downstream of European cities are especially sparse.Here we report from aircraft-borne CH4 in-situ measurements as conducted during the HALO aircraft campaign EMeRGe (Effect of Megacities on the Transport and Transformation of Pollutants on the Regional to Global Scales) in July 2017, which was led by the University of Bremen, Germany. During seven research flights, emissions from a variety of European (Mega)-cities were probed at different altitudes from 3km down to 500m, including measurements in the outflows of London, Rome, Po Valley, Ruhr and Benelux. We will present and compare the CH4 distribution measured downstream of the various studied urban hot-spots. With the help of other trace gas measurements (including e.g. CO2, CO, O3, SO2), observed methane enhancements will be attributed to the different potential source types. Finally, by the combination of in-situ measurements and regional model simulations using the EMAC-MECO(n) model, the contribution of emissions from urban centers to the regional methane budget over Europe will be discussed.

Solid methane on Triton and Pluto - 3- to 4-micron spectrophotometry

Science.gov (United States)

Spencer, John R.; Buie, Marc W.; Bjoraker, Gordon L.

1990-01-01

Methane has been identified in the Pluto/Charon system on the basis of absorption features in the reflectance spectrum at 1.5 and 2.3 microns; attention is presently given to observations of a 3.25 micron-centered deep absorption feature in Triton and Pluto/Charon system reflectance spectra. This absorption may indicate the presence of solid methane, constituting either the dominant surface species or a mixture with a highly transparent substance, such as N2 frost.

Liquid hydrogen production via hydrogen sulfide methane reformation

Science.gov (United States)

Huang, Cunping; T-Raissi, Ali

Hydrogen sulfide (H 2S) methane (CH 4) reformation (H 2SMR) (2H 2S + CH 4 = CS 2 + 4H 2) is a potentially viable process for the removal of H 2S from sour natural gas resources or other methane containing gases. Unlike steam methane reformation that generates carbon dioxide as a by-product, H 2SMR produces carbon disulfide (CS 2), a liquid under ambient temperature and pressure-a commodity chemical that is also a feedstock for the synthesis of sulfuric acid. Pinch point analyses for H 2SMR were conducted to determine the reaction conditions necessary for no carbon lay down to occur. Calculations showed that to prevent solid carbon formation, low inlet CH 4 to H 2S ratios are needed. In this paper, we analyze H 2SMR with either a cryogenic process or a membrane separation operation for production of either liquid or gaseous hydrogen. Of the three H 2SMR hydrogen production flowsheets analyzed, direct liquid hydrogen generation has higher first and second law efficiencies of exceeding 80% and 50%, respectively.

Preparation of CH4 for 14C measurements

International Nuclear Information System (INIS)

Cechova, A.; Grgula, M.; Povinec, P.; Sivo, A.

1988-01-01

An improved method of methane preparation from wood samples is described. It consists of the preparation of α-cellulose to secure a complete removal of contamination from the wood, its combustion to the form of CO 2 and the preparation of CH 4 in a new designed hydrogenation converter. Purified methane is suitable as a gas filling of the proportional counter. (author). 1 fig., 16 ref

Characteristics of Sr0.92Y0.08Ti1-yNiyO3-δ anode and Ni-infiltrated Sr0.92Y0.08TiO3-δ anode using CH4 fuel in solid oxide fuel cells

Science.gov (United States)

Park, Eun Kyoung; Lee, Soonil; Yun, Jeong Woo

2018-01-01

Strontium titanium oxide co-doped with yttrium and nickel (SrxY1-xTiyNi1-yO3-δ; hereafter, SYTN), was investigated as an alternative anode material for solid oxide fuel cells. To improve the ionic conductivity of the Sr0.92Y0.08TiO3-δ (SYT) anode, Ni2+ was substituted into the B-site (initially occupied by Ti4+), thereby forming oxygen vacancies. To analyze the effects of Ni-doping in the SYT anode, the electrochemical properties of the SYTN anode were compared with those of the Ni-infiltrated SYT(Ni@SYT) using H2 and CH4 as fuels. The electrochemical reactions at the SYTN anode in the presence of both H2 and CH4 were limited by relatively slow reactions, such as non-charged processes including oxygen surface exchange and solid surface diffusion. The high electrical conductivity and excellent catalytic activity of the Ni nanoparticles in the Ni@SYT anode led to improved cell performance. CH4 decomposition at the Ni@SYT anode occurred via thermal pyrolysis of CH4 rather than by steam methane reforming, resulting in carbon deposition. In comparison, the poor inherent catalytic activity for CH4 oxidation exhibited by the SYTN anode minimized carbon deposition on the anode surface.

Anaerobic Biodegradability and Methane Potential of Crop Residue Co-Digested with Buffalo Dung

Directory of Open Access Journals (Sweden)

Abdul Razaque Sahito

2013-07-01

Full Text Available ABD (Anaerobic Biodegradability and BMP (Biochemical Methane Potential of banana plant waste, canola straw, cotton stalks, rice straw, sugarcane trash and wheat straw co-digested with buffalo dung was evaluated through AMPTS (Automatic Methane Potential Test System. The substrates were analyzed for moisture, TS (Total Solids and VS (Volatile Solids, ultimate analysis (CHONS, pH and TA (Total Alkalinity. The BMPobserved during incubation of 30 days at the temperature of 37±0.2°C was 322 Nml CH4/g VSadd for wheat straw followed by 260, 170, 149, 142 and 138 Nml CH4/gVSadd for canola straw, rice straw, cotton stalks, banana plant waste and sugarcane trash respectively, whereas the maximum theoretical BMP was 481 Nml CH4/gVSadd for cotton stalks, followed by 473, 473, 446, 432 and 385 Nml CH4/gVSadd for wheat straw, banana plant waste, canola straw, rice straw and sugarcane trash respectively. The percentage ABD values were in the range of 68-30%. In addition to this, the effect of lignin content in the crop residue was evaluated on the ABD. The results of this study indicate that, the co-digestion of the crop residues with buffalo dung is feasible for production of renewable methane

In situ Low-temperature Pair Distribution Function (PDF) Analysis of CH4 and CO2 Hydrates

Science.gov (United States)

Cladek, B.; Everett, M.; McDonnell, M.; Tucker, M.; Keffer, D.; Rawn, C.

2017-12-01

Gas hydrates occur in ocean floor and sub-surface permafrost deposits and are stable at moderate to high pressures and low temperatures. They are a clathrate structure composed of hydrogen bonded water cages that accommodate a wide variety of guest molecules. CO2 and CH4 hydrates both crystallize as the cubic sI hydrate and can form a solid solution. Natural gas hydrates are interesting as a potential methane source and for CO2 sequestration. Long-range diffraction studies on gas hydrates give valuable structural information but do not provide a detailed understanding of the disordered gas molecule interactions with the host lattice. In-situ low temperature total scattering experiments combined with pair distribution function (PDF) analysis are used to investigate the gas molecule motions and guest-cage interactions. CO2 and methane hydrates exhibit different decomposition behavior, and CO2 hydrate has a smaller lattice parameter despite it being a relatively larger molecule. Total scattering studies characterizing both the short- and long-range order simultaneously help to elucidate the structural source of these phenomena. Low temperature neutron total scattering data were collected using the Nanoscale Ordered MAterials Diffractometer (NOMAD) beamline at the Spallation Neutron Source (SNS) on CO2 and CH4 hydrates synthesized with D2O. Guest molecule motion within cages and interactions between gases and cages are investigated through the hydrate stability and decomposition regions. Data were collected from 2-80 K at a pressure of 55 mbar on CO2 and CH4 hydrates, and from 80-270 K at 25 bar on CH4 hydrate. The hydrate systems were modeled with classical molecular dynamic (MD) simulations to provide an analysis of the total energy into guest-guest, guest-host and host-host contributions. Combined Reitveld and Reverse Monte Carlo (RMC) structure refinement were used to fit models of the data. This combined modeling and simulation characterizes the effects of CO2 and

Local- and regional-scale measurements of CH4, δ13CH4, and C2H6 in the Uintah Basin using a mobile stable isotope analyzer

Science.gov (United States)

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.

Dual stable isotopes of CH 4 from Yellowstone hot-springs suggest hydrothermal processes involving magmatic CO 2

Energy Technology Data Exchange (ETDEWEB)

Moran, James J.; Whitmore, Laura M.; Jay, Zackary J.; Jennings, Ryan deM.; Beam, Jacob P.; Kreuzer, Helen W.; Inskeep, William P.

2017-07-01

Volcanism and post-magmatism contribute both significant annual CH₄ fluxes to the atmosphere (on par with other natural sources such as forest fire and wild animal emissions) and have been implicated in past climate-change events. The Yellowstone hot spot is one of the largest volcanic systems on Earth and is known to emit methane in addition to other greenhouse gases (e.g. carbon dioxide) but the ultimate source of this methane flux has not been elucidated. Here we use dual stable isotope analysis (δ²H and δ¹³C) of CH₄(g) sampled from ten high-temperature geothermal pools in Yellowstone National Park to show that the predominant flux of CH4(g) is abiotic. The average δ¹³C and δ²H values of CH₄(g) emitted from hot springs (-26.7 (±2.4) and -236.9 (±12.0) ‰, respectively) are not consistent with biotic (microbial or thermogenic) methane sources, but are within previously reported ranges for abiotic methane production. Correlation between δ¹³C_CH4 and δ¹³C-dissolved inorganic C (DIC) also suggests that CO₂ is a parent C source for the observed CH₄(g). Moreover, CH₄-CO₂ isotopic geothermometry was used to estimate CH₄(g) formation temperatures ranging from ~ 250 - 350°C, which is just below the temperature estimated for the hydrothermal reservoir and consistent with the hypothesis that subsurface, rock-water interactions are responsible for large methane fluxes from this volcanic system. An understanding of conditions leading to the abiotic production of methane and associated isotopic signatures are central to understanding the evolutionary history of deep carbon sources on Earth.

Disproportionation and thermochemical sulfate reduction reactions in S-H20-Ch4 and S-D2O-CH4 systems from 200 to 340 °C at elevated pressures

Science.gov (United States)

Yuan, Shunda; Chou, I-Ming; Burruss, Robert A.

2013-01-01

Elemental sulfur, as a transient intermediate compound, by-product, or catalyst, plays significant roles in thermochemical sulfate reduction (TSR) reactions. However, the mechanisms of the reactions in S-H2O-hydrocarbons systems are not clear. To improve our understanding of reaction mechanisms, we conducted a series of experiments between 200 and 340 °C for S-H2O-CH4, S-D2O-CH4, and S-CH4-1m ZnBr2 systems in fused silica capillary capsules (FSCC). After a heating period ranging from 24 to 2160 hours (hrs), the quenched samples were analyzed by Raman spectroscopy. Combined with the in situ Raman spectra collected at high temperatures and pressures in the S-H2O and S-H2O-CH4 systems, our results showed that (1) the disproportionation of sulfur in the S-H2O-CH4 system occurred at temperatures above 200 °C and produced H2S, SO42-, and possibly trace amount of HSO4-; (2) sulfate (and bisulfate), in the presence of sulfur, can be reduced by methane between 250 and 340 °C to produce CO2 and H2S, and these TSR temperatures are much closer to those of the natural system (2O-CH4 system may take place simultaneously, with TSR being favored at higher temperatures; and (4) in the system S-D2O-CH4, both TSR and the competitive disproportionation reactions occurred simultaneously at temperatures above 300 °C, but these reactions were very slow at lower temperatures. Our observation of methane reaction at 250 °C in a laboratory time scale suggests that, in a geologic time scale, methane may be destroyed by TSR reactions at temperatures > 200 °C that can be reached by deep drilling for hydrocarbon resources.

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

Science.gov (United States)

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...

Summary of LOX/CH4 Thruster Technology Development at NASA/MSFC

Science.gov (United States)

Greene, Sandra Elam

2015-01-01

In recent years, a variety of injectors for liquid oxygen (LOX) and methane (CH4) propellant systems have been designed, fabricated, and demonstrated with hot-fire testing at Marshall Space Flight Center (MSFC). Successful designs for liquid methane (LCH4) and gaseous methane (GCH4) have been developed. A variety of chambers, including a transpiration cooled design, along with uncooled ablatives and refractory metals, have also been hot-fire tested by MSFC for use with LOX/LCH4 injectors. Hot-fire testing has also demonstrated multiple ignition source options. Heat flux data for selected injectors has been gathered by testing with a calorimeter chamber. High performance and stable combustion have been demonstrated, along with designs for thrust levels ranging from 500 to 7,000 lbf. The newest LOX/CH4 injector and chamber developed by MSFC have been fabricated with additive manufacturing techniques and include unique design features to investigate regenerative cooling with methane. This low cost and versatile hardware offers a design for 4,000 lbf thrust and will be hot-fire tested at MSFC in 2015. Its design and operation can easily be scaled for use in systems with thrust levels up to 25,000 lbf.

Quantifying the relative contribution of natural gas fugitive emissions to total methane emissions in Colorado, Utah, and Texas using mobile δ13CH4 analysis

Science.gov (United States)

Rella, C.; Crosson, E.; Petron, G.; Sweeney, C.; Karion, A.

2013-12-01

Fugitive emissions of methane into the atmosphere are a major concern facing the natural gas production industry. Because methane is more energy-rich than coal per kg of CO2 emitted into the atmosphere, it represents an attractive alternative to coal for electricity generation, provided that the fugitive emissions of methane are kept under control. A key step in assessing these emissions in a given region is partitioning the observed methane emissions between natural gas fugitive emissions and other sources of methane, such as from landfills or agricultural activities. One effective method for assessing the contribution of these different sources is stable isotope analysis, using the δ13CH4 signature to distinguish between natural gas and landfills or ruminants. We present measurements of mobile field δ13CH4 using a spectroscopic stable isotope analyzer based on cavity ringdown spectroscopy, in three intense natural gas producing regions of the United States: the Denver-Julesburg basin in Colorado, the Uintah basin in Utah, and the Barnett Shale in Texas. Mobile isotope measurements of individual sources and in the nocturnal boundary layer have been combined to establish the fraction of the observed methane emissions that can be attributed to natural gas activities. The fraction of total methane emissions in the Denver-Julesburg basin attributed to natural gas emissions is 78 +/- 13%. In the Uinta basin, which has no other significant sources of methane, the fraction is 96% +/- 15%. In addition, results from the Barnett shale are presented, which includes a major urban center (Dallas / Ft. Worth). Methane emissions in this region are spatially highly heterogeneous. Spatially-resolved isotope and concentration measurements are interpreted using a simple emissions model to arrive at an overall isotope ratio for the region. (left panel) Distribution of oil and gas well pads (yellow) and landfills (blue) in the Dallas / Ft. Worth area. Mobile nocturnal measurements

Methane emissions from digestate at an agricultural biogas plant.

Science.gov (United States)

Baldé, Hambaliou; VanderZaag, Andrew C; Burtt, Stephen D; Wagner-Riddle, Claudia; Crolla, Anna; Desjardins, Raymond L; MacDonald, Douglas J

2016-09-01

Methane (CH4) emissions were measured over two years at an earthen storage containing digestate from a mesophilic biodigester in Ontario, Canada. The digester processed dairy manure and co-substrates from the food industry, and destroyed 62% of the influent volatile solids (VS). Annual average emissions were 19gCH4m(-3)d(-1) and 0.27gCH4kg(-1)VSd(-1). About 76% of annual emissions occurred from June to October. Annual cumulative emissions from digestate corresponded to 12% of the CH4 produced within the digester. A key contributor to CH4 emissions was the sludge layer in storage, which contained as much VS as the annual discharge from the digester. These findings suggest that digestate management provides an opportunity to further enhance the benefits of biogas (i.e. reducing CH4 emissions compared to undigested liquid manure, and producing renewable energy). Potential best practices for future study include complete storage emptying, solid-liquid separation, and storage covering. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Liquid hydrogen production via hydrogen sulfide methane reformation

Energy Technology Data Exchange (ETDEWEB)

Huang, Cunping; T-Raissi, Ali [University of Central Florida, Florida Solar Energy Center, 1769 Clearlake Road, Cocoa, FL 32922 (United States)

2008-01-03

Hydrogen sulfide (H{sub 2}S) methane (CH{sub 4}) reformation (H{sub 2}SMR) (2H{sub 2}S + CH{sub 4} = CS{sub 2} + 4H{sub 2}) is a potentially viable process for the removal of H{sub 2}S from sour natural gas resources or other methane containing gases. Unlike steam methane reformation that generates carbon dioxide as a by-product, H{sub 2}SMR produces carbon disulfide (CS{sub 2}), a liquid under ambient temperature and pressure - a commodity chemical that is also a feedstock for the synthesis of sulfuric acid. Pinch point analyses for H{sub 2}SMR were conducted to determine the reaction conditions necessary for no carbon lay down to occur. Calculations showed that to prevent solid carbon formation, low inlet CH{sub 4} to H{sub 2}S ratios are needed. In this paper, we analyze H{sub 2}SMR with either a cryogenic process or a membrane separation operation for production of either liquid or gaseous hydrogen. Of the three H{sub 2}SMR hydrogen production flowsheets analyzed, direct liquid hydrogen generation has higher first and second law efficiencies of exceeding 80% and 50%, respectively. (author)

Correction: Large-scale electricity storage utilizing reversible solid oxide cells combined with underground storage of CO2 and CH4

DEFF Research Database (Denmark)

Jensen, Søren Højgaard; Graves, Christopher R.; Mogensen, Mogens Bjerg

2017-01-01

Correction for ‘Large-scale electricity storage utilizing reversible solid oxide cells combined with underground storage of CO2 and CH4’ by S. H. Jensen et al., Energy Environ. Sci., 2015, 8, 2471–2479.......Correction for ‘Large-scale electricity storage utilizing reversible solid oxide cells combined with underground storage of CO2 and CH4’ by S. H. Jensen et al., Energy Environ. Sci., 2015, 8, 2471–2479....

Anaerobic biodegradability and methane potential of crop residue co-digested with buffalo dung

International Nuclear Information System (INIS)

Sahito, A.R.; Mahar, R.B.; Brohi, K.M.

2013-01-01

ABD (Anaerobic Biodegradability) and BMP (Biochemical Methane Potential) of banana plant waste, canola straw, cotton stalks, rice straw, sugarcane trash and wheat straw co-digested with buffalo dung was evaluated through AMPTS (Automatic Methane Potential Test System). The substrates were analyzed for moisture, TS (Total Solids) and VS (Volatile Solids), ultimate analysis (CHONS), pH and TA (Total Alkalinity). The BMP/sub observed/ during incubation of 30 days at the temperature of 37+-0.2+-degree C was 322 Nml CH4/g VSadd for wheat straw followed by 260, 170, 149, 142 and 138 Nml CH4/gVS/sub add/ for canola straw, rice straw, cotton stalks, banana plant waste and sugarcane trash respectively, whereas the maximum theoretical BMP was 481 Nml CH/sub 4//gVS/sub add/ for cotton stalks, followed by 473, 473, 446, 432 and 385 Nml CH/sub 4//gVS/sub add/ for wheat straw, banana plant waste, canola straw, rice straw and sugarcane trash respectively. The percentage ABD values were in the range of 68-30%. In addition to this, the effect of lignin content in the crop residue was evaluated on the ABD. The results of this study indicate that, the co-digestion of the crop residues with buffalo dung is feasible for production of renewable methane. (author)

Non-CO2 greenhouse gas emissions associated with food production: methane (CH4) and nitrous oxide (N2O)

International Nuclear Information System (INIS)

Carlsson-Kanyama, Annika

2007-01-01

It is well known that the agriculture and livestock sectors are large contributors of N 2 O and CH 4 emissions in countries with agricultural activities and that remedial measures are needed in these sectors in order to curb contributions to global warming. This study examines non- CO 2 greenhouse gas emissions associated with the production of food. Methane (CH 4 ) and nitrous oxide (N 2 O) are the most relevant greenhouse gases in this category, and they are emitted mainly in the agricultural sector. These greenhouse gases have a Global Warming Potential much higher than CO 2 itself (25- and 298-fold higher, respectively, in a 100-year perspective). Emission intensities and the corresponding uncertainties were calculated based on the latest procedures and data published by the Intergovernmental Panel on Climate Change and used to facilitate calculations comparing greenhouse gas emissions for food products and diets. When the proposed emission intensities were applied to agricultural production, the results showed products of animal origin and the cultivation of rice under water to have high emissions compared with products of vegetable origin cultivated on upland soils, such as wheat and beans. In animal production the main source of greenhouse gas emissions was methane from enteric fermentation, while emissions of nitrous oxides from fertilisers were the main sources of greenhouse gas emissions for cereal and legume cultivation. For rice cultivation, methane emissions from flooded rice fields contributed most. Other significant sources of greenhouse gas emissions during animal production were manure storage and management. We suggest that the proposed emission factors, together with the associated uncertainties, can be a tool for better understanding the potential to mitigate emissions of greenhouse gases through changes in the diet

Effects of plant species on soil microbial processes and CH4 emission from constructed wetlands

International Nuclear Information System (INIS)

Wang, Yanhua; Yang, Hao; Ye, Chun; Chen, Xia; Xie, Biao; Huang, Changchun; Zhang, Jixiang; Xu, Meina

2013-01-01

Methane (CH 4 ) emission from constructed wetland has raised environmental concern. This study evaluated the influence of mono and polyculture constructed wetland and seasonal variation on CH 4 fluxes. Methane emission data showed large temporal variation ranging from 0 to 249.29 mg CH 4 m −2 h −1 . Results indicated that the highest CH 4 flux was obtained in the polyculture system, planted with Phragmites australis, Zizania latifolia and Typha latifolia, reflecting polyculture system could stimulate CH 4 emission. FISH analysis showed the higher amount of methanotrophs in the profile of Z. latifolia in both mono and polyculture systems. The highest methanogens amount and relatively lower methanotrophs amount in the profile of polyculture system were obtained. The results support the characteristics of CH 4 fluxes. The polyculture constructed wetland has the higher potential of global warming. -- Highlights: ► The polyculture constructed wetland has the higher contribution to CH 4 emission. ► The CH 4 –C conversion ranged from 0 to 3.7%. ► The Z. latifolia played important roles in methanotrophs growth and CH 4 consumption. ► Major influence of T-N, TOC and plant cover on CH 4 emission was obtained. -- The polyculture constructed wetland has the higher contribution to global warming

Microwave Spectrum and Structure of the Methane-Propane Complex

Science.gov (United States)

Peterson, Karen I.; Lin, Wei; Arsenault, Eric A.; Choi, Yoon Jeong; Novick, Stewart E.

2017-06-01

Methane is exceptional in its solid-phase orientational disorder that persists down to 24 K. Only below that temperature does the structure become partially ordered, and full crystallinity requires even lower temperatures and high pressures. Not surprisingly, methane appears to freely rotate in most van der Waals complexes, although two notable exceptions are CH_4-HF and CH_4-C_5H_5N. Of interest to us is how alkane interactions affect the methane rotation. Except for CH_4-CH_4, rotationally-resolved spectra of alkane-alkane complexes have not been studied. To fill this void, we present the microwave spectrum of CH_4-C_3H_8 which is the smallest alkane complex with a practical dipole moment. The microwave spectrum of CH_4-C_3H_8 was measured using the Fourier Transform microwave spectrometer at Wesleyan University. In the region between 7100 and 25300 MHz, we observed approximately 70 transitions that could plausibly be attributed to the CH_4-C_3H_8 complex (requiring high power and the proper mixture of gases). Of these, 16 were assigned to the A-state (lowest internal rotor state of methane) and four to the F-state. The A-state transitions were fitted with a Watson Hamiltonian using nine spectroscopic constants of which A = 7553.8144(97) MHz, B = 2483.9183(35) MHz, and C = 2041.8630(21) MHz. The A rotational constant is only 1.5 MHz higher than that of Ar-C_3H_8 and, since the a-axis of the complex passes approximately through the centers of mass of the subunits, this indicates a similar relative orientation. Thus, we find that the CH_4 is located above the plane of the propane. The center-of-mass separation of the subunits in CH_4-C_3H_8 is calculated to be 3.993 Å, 0.16 Å longer than the Ar-C_3H_8 distance of 3.825 Å, a reasonable difference considering the larger van der Waals radius of CH_4. The four F-state lines, which were about twice as strong as the A-state lines, could be fitted to A, B, and C rotational constants, and further analysis is in progress.

Terrestrial plant methane production

DEFF Research Database (Denmark)

Mikkelsen, Teis Nørgaard; Bruhn, Dan; Møller, Ian M.

We evaluate all experimental work published on the phenomenon of aerobic methane (CH4) generation in terrestrial plants. We conclude that the phenomenon is true. Four stimulating factors have been observed to induce aerobic plant CH4 production, i.e. cutting injuries, increasing temperature...... the aerobic methane emission in plants. Future work is needed for establishing the relative contribution of several proven potential CH4 precursors in plant material....

Microwave Pretreatments of Switchgrass Leaf and Stem Fractions to Increase Methane Production

Directory of Open Access Journals (Sweden)

Chunhui Wu

2015-05-01

Full Text Available The objective of this study was to determine the effectiveness of microwave pretreatments on methane production from two switchgrass tissues (leaf vs. stem. The methane production from the leaf fraction was significantly affected by the microwave final temperature, while production from the stem fraction was affected by the combination of the microwave final temperature and heating rate. Thus, the highest methane yield from the leaf (134.81 mL CH4/g of volatile solids (VS was obtained at 100 °C, while the highest yield from the stem (99.35 mL CH4/g VS was obtained at 150 °C, with a heating rate of 10 °C/min. Although methane production from the leaf fraction was merely enhanced by 9.1% after microwave pretreatments, the time required to reach 80% of ultimate methane production was reduced by 12 days. For the stem fraction, methane production was improved by 5.2% after microwave pretreatment, and the time to obtain 80% of ultimate methane production increased.

Uncertainties in modelling CH4 emissions from northern wetlands in glacial climates: effect of hydrological model and CH4 model structure

Directory of Open Access Journals (Sweden)

J. van Huissteden

2009-07-01

Full Text Available Methane (CH4 fluxes from northern wetlands may have influenced atmospheric CH4 concentrations at climate warming phases during the last 800 000 years and during the present global warming. Including these CH4 fluxes in earth system models is essential to understand feedbacks between climate and atmospheric composition. Attempts to model CH4 fluxes from wetlands have previously been undertaken using various approaches. Here, we test a process-based wetland CH4 flux model (PEATLAND-VU which includes details of soil-atmosphere CH4 transport. The model has been used to simulate CH4 emissions from continental Europe in previous glacial climates and the current climate. This paper presents results regarding the sensitivity of modeling glacial terrestrial CH4 fluxes to (a basic tuning parameters of the model, (b different approaches in modeling of the water table, and (c model structure. In order to test the model structure, PEATLAND-VU was compared to a simpler modeling approach based on wetland primary production estimated from a vegetation model (BIOME 3.5. The tuning parameters are the CH4 production rate from labile organic carbon and its temperature sensitivity. The modelled fluxes prove comparatively insensitive to hydrology representation, while sensitive to microbial parameters and model structure. Glacial climate emissions are also highly sensitive to assumptions about the extent of ice cover and exposed seafloor. Wetland expansion over low relief exposed seafloor areas have compensated for a decrease of wetland area due to continental ice cover.

Stimulation of methane oxidation potential and effects on vegetation growth by bottom ash addition in a landfill final evapotranspiration cover

NARCIS (Netherlands)

Kim, G.W.; Ho, A.; Kim, P.J.; Kim, Sang Yun

2016-01-01

The landfilling of municipal solid waste is a significant source of atmospheric methane (CH4), contributing up to 20% of total anthropogenic CH4 emissions. The evapotranspiration (ET) cover system, an alternative final cover system in waste landfills, has been considered to be a promising way to

LOW-TEMPERATURE EQUATION OF STATE OF SOLID METHANE

Directory of Open Access Journals (Sweden)

L. N. Yakub

2016-02-01

Full Text Available The theoretical equation of state for solid methane, developed within the framework of perturbation theory, with the crystal consisting of spherical molecules as zero-order approximation, and octupole – octupole interaction of methane molecules as a perturbation, is proposed. Thermodynamic functions are computed on the sublimation line up to the triple point. The contribution of the octupole – octupole interaction to the thermodynamic properties of solid methane is estimated.

Adsorption of CH4 on nitrogen- and boron-containing carbon models of coal predicted by density-functional theory

Science.gov (United States)

Liu, Xiao-Qiang; Xue, Ying; Tian, Zhi-Yue; Mo, Jing-Jing; Qiu, Nian-Xiang; Chu, Wei; Xie, He-Ping

2013-11-01

Graphene doped by nitrogen (N) and/or boron (B) is used to represent the surface models of coal with the structural heterogeneity. Through the density functional theory (DFT) calculations, the interactions between coalbed methane (CBM) and coal surfaces have been investigated. Several adsorption sites and orientations of methane (CH4) on graphenes were systematically considered. Our calculations predicted adsorption energies of CH4 on graphenes of up to -0.179 eV, with the strongest binding mode in which three hydrogen atoms of CH4 direct to graphene surface, observed for N-doped graphene, compared to the perfect (-0.154 eV), B-doped (-0.150 eV), and NB-doped graphenes (-0.170 eV). Doping N in graphene increases the adsorption energies of CH4, but slightly reduced binding is found when graphene is doped by B. Our results indicate that all of graphenes act as the role of a weak electron acceptor with respect to CH4. The interactions between CH4 and graphenes are the physical adsorption and slightly depend upon the adsorption sites on graphenes and the orientations of methane as well as the electronegativity of dopant atoms in graphene.

Activation of methane by zinc: gas-phase synthesis, structure, and bonding of HZnCH3.

Science.gov (United States)

Flory, Michael A; Apponi, Aldo J; Zack, Lindsay N; Ziurys, Lucy M

2010-12-08

The methylzinc hydride molecule, HZnCH3, has been observed in the gas phase for the first time in the monomeric form using high-resolution spectroscopic techniques. The molecule was synthesized by two methods: the reaction of dimethylzinc with hydrogen gas and methane in an AC discharge and the reaction of zinc vapor produced in a Broida-type oven with methane in a DC discharge. HZnCH3 was identified on the basis of its pure rotational spectrum, which was recorded using millimeter/submillimeter direct-absorption and Fourier transform microwave techniques over the frequency ranges 332-516 GHz and 18-41 GHz, respectively. Multiple rotational transitions were measured for this molecule in seven isotopic variants. K-ladder structure was clearly present in all of the spectra, indicating a molecule with C3v symmetry and a (1)A1 ground electronic state. Extensive quadrupole hyperfine structure arising from the (67)Zn nucleus was observed for the H(67)ZnCH3 species, suggesting covalent bonding to the zinc atom. From the multiple isotopic substitutions, a precise structure for HZnCH3 has been determined. The influence of the axial hydrogen atom slightly distorts the methyl group but stabilizes the Zn-C bond. This study suggests that HZnCH3 can be formed through the oxidative addition of zinc to methane in the gas phase under certain conditions. HZnCH3 is the first metal-methane insertion complex to be structurally characterized.

Effects of water vapor on the radiolysis of methane over molecular sieve 5A

International Nuclear Information System (INIS)

Shimizu, Y.; Nagai, S.

1989-01-01

Effects of the addition of H 2 O on the radiation-induced chemical reaction of methane over molecular sieve 5A at 460 0 C have been studied by product analysis. Hydrogen, carbon monoxide, carbon dioxide and hydrocarbons consisting mainly of C 2 and C 3 alkanes and alkenes were produced from CH 4 + H 2 O mixtures at high conversion levels. The yields of hydrocarbons from 3:1 and 3:2 CH 4 + H 2 O mixtures decreased slightly with time but those from 3:4 mixture showed no decrease with time. When the molecular sieve 5A that had been irradiated in flowing methane was reirradiated in the presence of H 2 O, carbonaceous solid produced from methane on molecular sieve 5A was readily decomposed to carbon dioxide, carbon monoxide, hydrogen and hydrocarbons, mainly alkanes. Therefore, it is concluded that the suppression of decrease of product yields with time by the addition of H 2 O is mainly ascribed to decomposition of the carbonaceous solid by H 2 O under electron beam irradiation. The role of added H 2 O is also discussed in connection with the conventional methane-steam reforming reaction. (author)

The Extent of CH4 Emission and Oxidation in Thermogenic and Biogenic Gas Hydrate Environments

Science.gov (United States)

Kastner, M.; Solem, C.; Bartlett, D.; MacDonald, I.; Valentine, D.

2003-12-01

The role of methane hydrate in the global methane budget is poorly understood, because relatively little is known about the transport of gaseous and dissolved methane through the seafloor into the ocean, from the water column into the atmosphere, and the extent of water-column methanotrophy that occurs en route. We characterize the transport and consumption of methane in three distinct gas hydrate environments, spanning the spectrum of thermogenic and biogenic methane occurrences: Bush Hill in the Gulf of Mexico, Eel River off the coast of Northern California, and the Noth and South Hydrate Ridges on the Cascadia Oregon margin. At all the sites studied a significant enrichment in δ 13CH4 with distance along isopycnals away from the methane source is observed, indicative of extensive aerobic bacterial methane oxidation in the water column. The effects of this process are principally pronounced in the mostly biogenic methane setting, with δ 13C-CH4 measured as high as -12 permil (PDB) between North and South Hydrate Ridge. The δ 13C-CH4 values ranged from -12 to -67 permil at Hydrate Ridge, -34 to -52 permil at Eel River, and -41 to -49 permil at Bush Hill. The large variation in methane carbon isotope ranges between the sites suggest that major differences exist in both the rates of aerobic methane oxidation and system openness at the studied locations. A mean kinetic isotope fractionation factor is being determined using a closed-system Rayleigh distillation model. An approximate regional methane flux from the ocean into the atmosphere is being estimated for the Gulf of Mexico, by extrapolation of the flux value from the Bush Hill methane plume over 390 plume locations having persistent oil slicks on the ocean surface, mapped by time series satellite data.

Activity of type i methanotrophs dominates under high methane concentration: Methanotrophic activity in slurry surface crusts as influenced by methane, oxygen, and inorganic nitrogen

DEFF Research Database (Denmark)

Duan, Yun Feng; Reinsch, Sabine; Ambus, Per

2017-01-01

Livestock slurry is a major source of atmospheric methane (CH4), but surface crusts harboring methane-oxidizing bacteria (MOB) could mediate against CH4 emissions. This study examined conditions for CH4 oxidation by in situ measurements of oxygen (O2) and nitrous oxide (N2O), as a proxy for inorg......Livestock slurry is a major source of atmospheric methane (CH4), but surface crusts harboring methane-oxidizing bacteria (MOB) could mediate against CH4 emissions. This study examined conditions for CH4 oxidation by in situ measurements of oxygen (O2) and nitrous oxide (N2O), as a proxy...... for inorganic N transformations, in intact crusts using microsensors. This was combined with laboratory incubations of crust material to investigate the effects of O2, CH4, and inorganic N on CH4 oxidation, using 13CH4 to trace C incorporation into lipids of MOB. Oxygen penetration into the crust was 2 to 14 mm...

Study of the daily and seasonal atmospheric CH4 mixing ratio variability in a rural Spanish region using 222Rn tracer

Science.gov (United States)

Grossi, Claudia; Vogel, Felix R.; Curcoll, Roger; Àgueda, Alba; Vargas, Arturo; Rodó, Xavier; Morguí, Josep-Anton

2018-04-01

The ClimaDat station at Gredos (GIC3) has been continuously measuring atmospheric (dry air) mixing ratios of carbon dioxide (CO2) and methane (CH4), as well as meteorological parameters, since November 2012. In this study we investigate the atmospheric variability of CH4 mixing ratios between 2013 and 2015 at GIC3 with the help of co-located observations of 222Rn concentrations, modelled 222Rn fluxes and modelled planetary boundary layer heights (PBLHs). Both daily and seasonal changes in atmospheric CH4 can be better understood with the help of atmospheric concentrations of 222Rn (and the corresponding fluxes). On a daily timescale, the variation in the PBLH is the main driver for 222Rn and CH4 variability while, on monthly timescales, their atmospheric variability seems to depend on emission changes. To understand (changing) CH4 emissions, nocturnal fluxes of CH4 were estimated using two methods: the radon tracer method (RTM) and a method based on the EDGARv4.2 bottom-up emission inventory, both using FLEXPARTv9.0.2 footprints. The mean value of RTM-based methane fluxes (FR_CH4) is 0.11 mg CH4 m-2 h-1 with a standard deviation of 0.09 or 0.29 mg CH4 m-2 h-1 with a standard deviation of 0.23 mg CH4 m-2 h-1 when using a rescaled 222Rn map (FR_CH4_rescale). For our observational period, the mean value of methane fluxes based on the bottom-up inventory (FE_CH4) is 0.33 mg CH4 m-2 h-1 with a standard deviation of 0.08 mg CH4 m-2 h-1. Monthly CH4 fluxes based on RTM (both FR_CH4 and FR_CH4_rescale) show a seasonality which is not observed for monthly FE_CH4 fluxes. During January-May, RTM-based CH4 fluxes present mean values 25 % lower than during June-December. This seasonal increase in methane fluxes calculated by RTM for the GIC3 area appears to coincide with the arrival of transhumant livestock at GIC3 in the second half of the year.

Neutron scattering and proton spin conversion in solid CH4

International Nuclear Information System (INIS)

Lushington, K.J.; Morrison, J.A.

1977-01-01

The total neutron cross section of pure and O 2 -doped condensed CH 4 has been measured in the temperature range 0.75< T<100 K. The neutron wave length was sufficiently long (4.7 A) so that changes in cross section could be directly related to changes in γI(I + 1)μ, the mean squared proton nuclear angular momentum per molecule, to a sensitivity of about 1%. The temperature dependences of γI(I + 1)μ for the pure and doped specimens differ considerably in solid phase II(T<20.4 K). For the former specimen, the change in cross section is consistent with conversion occurring between the nuclear spin symmetry species on the orientationally disordered sublattices only. The addition of oxygen enhances the rate of conversion such that the value of γI(I + 1)μ corresponds to conversion on both the disordered and ordered sublattices. The characteristic lifetimes of the catalyzed and uncatalyzed conversion processes have been estimated. (author)

Genomic selection for methane emission

DEFF Research Database (Denmark)

de Haas, Yvette; Pryce, Jennie E; Wall, Eileen

2016-01-01

Climate change is a growing area of international concern, and it is well established that the release of greenhouse gases (GHG) is a contributing factor. Of the various GHG produced by ruminants, enteric methane (CH4 ) is the most important contributor. One mitigation strategy is to reduce methane...... emission through genetic selection. Our first attempt used beef cattle and a GWAS to identify genes associated with several CH4 traits in Angus beef cattle. The Angus population consisted of 1020 animals with phenotypes on methane production (MeP), dry matter intake (DMI), and weight (WT). Additionally......, two new methane traits: residual genetic methane (RGM) and residual phenotypic methane (RPM) were calculated by adjusting CH4 for DMI and WT. Animals were genotyped using the 800k Illumina Bovine HD Array. Estimated heritabilities were 0.30, 0.19 and 0.15 for MeP, RGM and RPM respectively...

Isotopic source signatures: Impact of regional variability on the δ13CH4 trend and spatial distribution

Science.gov (United States)

Feinberg, Aryeh I.; Coulon, Ancelin; Stenke, Andrea; Schwietzke, Stefan; Peter, Thomas

2018-02-01

The atmospheric methane growth rate has fluctuated over the past three decades, signifying variations in methane sources and sinks. Methane isotopic ratios (δ13CH4) differ between emission categories, and can therefore be used to distinguish which methane sources have changed. However, isotopic modelling studies have mainly focused on uncertainties in methane emissions rather than uncertainties in isotopic source signatures. We simulated atmospheric δ13CH4 for the period 1990-2010 using the global chemistry-climate model SOCOL. Empirically-derived regional variability in the isotopic signatures was introduced in a suite of sensitivity simulations. These simulations were compared to a baseline simulation with commonly used global mean isotopic signatures. We investigated coal, natural gas/oil, wetland, livestock, and biomass burning source signatures to determine whether regional variations impact the observed isotopic trend and spatial distribution. Based on recently published source signature datasets, our calculated global mean isotopic signatures are in general lighter than the commonly used values. Trends in several isotopic signatures were also apparent during the period 1990-2010. Tropical livestock emissions grew during the 2000s, introducing isotopically heavier livestock emissions since tropical livestock consume more C4 vegetation than midlatitude livestock. Chinese coal emissions, which are isotopically heavy compared to other coals, increase during the 2000s leading to higher global values of δ13CH4 for coal emissions. EDGAR v4.2 emissions disagree with the observed atmospheric isotopic trend for almost all simulations, confirming past doubts about this emissions inventory. The agreement between the modelled and observed δ13CH4 interhemispheric differences improves when regional source signatures are used. Even though the simulated results are highly dependent on the choice of methane emission inventories, they emphasize that the commonly used

Modeling Plasma-based CO2 and CH4 Conversion in Mixtures with N2, O2 and H2O: the Bigger Plasma Chemistry Picture

KAUST Repository

Wang, Weizong; Snoeckx, Ramses; Zhang, Xuming; Cha, Min; Bogaerts, Annemie

2018-01-01

performed regarding the single component gases, i.e. CO2 splitting and CH4 reforming, as well as for two component mixtures, i.e. dry reforming of methane (CO2/CH4), partial oxidation of methane (CH4/O2), artificial photosynthesis (CO2/H2O), CO2

Infrared spectroscopy of water clusters isolated in methane matrices: Effects of isotope substitution and annealing

International Nuclear Information System (INIS)

Yamakawa, Koichiro; Ehara, Namika; Ozawa, Nozomi; Arakawa, Ichiro

2016-01-01

Using infrared-active solvents of CH_4 and CD_4 for matrix isolation, we measured infrared spectra of H_2O and D_2O clusters at 7 K. The solute-concentration dependence of the spectrum of H_2O clusters in a CH_4 matrix was investigated and was used for the peak assignment. Annealing procedures were found to promote the size growth of water clusters in methane matrices for all the combinations of (H_2O, CH_4), (H_2O, CD_4), (D_2O, CH_4), and (D_2O, CD_4). We also monitored the ν_3 absorption due to methane to find the annealing-induced structural change only of solid CH_4. The matrix effects on the vibrations of the clusters are discussed on the basis of “T_c plots”, where their frequencies are plotted as a function of the square root of the matrix critical temperature, T_c. The obtained plots assure the validity of the assignment of the cluster peaks.

Origin of the Ability of α-Fe2 O3 Mesopores to Activate C-H Bonds in Methane.

Science.gov (United States)

Dong, Bing; Han, Zhen; Zhang, Yongbo; Yu, Youyi; Kong, Aiguo; Shan, Yongkui

2016-02-01

Methane is a most abundant and inexpensive hydrocarbon feedstock for the production of chemicals and fuels. However, it is extremely difficult to directly convert methane to higher hydrocarbons because the C-H bonds in methane are the most stable C-H bonds of all hydrocarbons. The activation of the C-H bonds in methane by using an efficient and mild route remains a daunting challenge. Here, we show that the inner surface structures of the pore walls in mesoporous α-Fe 2 O 3 possess excellent catalytic performance for methane activation and convert C-H bonds into the C-O bonds in an O 2 atmosphere at 140 °C. We found that such unusual structures are mainly comprised of turbostratic ribbons and K crystal faces and have higher catalytic activity than the (110) plane. These results are without precedent in the history of catalysis chemistry and will provide a new pathway for designing and preparing highly efficient catalytic materials. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Landfill operation and waste management procedures in the reduction of methane and leachate pollutant emissions from municipal solid waste landfills

Energy Technology Data Exchange (ETDEWEB)

Jokela, J.

2002-07-01

The objective of the present research was to find ways of minimising emissions from municipal solid waste (MSW) landfills by means of laboratory experiments. During anaerobic incubation for 237 days, the grey waste components produced between 120 and 320 m{sup 3}CH{sub 4} tTS{sup -1} and between 0.32 and 3.5 kg NH{sub 4}-N tTS{sup -1} and the first-order rate constant of degradation ranged from 0.021 and 0.058 d{sup -1}. High amounts of COD and NH{sub 4}-N were observed in the leachate of grey waste in all the procedures tested during lysimeter experiments lasting 573 days. In the 10- year-old landfilled MSW, a high rate of methanisation was achieved with rainwater addition and leachate recirculation over 538 days, whereas initially pre-wetted grey waste and landfilled MSW were rapidly acidified, thus releasing a high amount of COD into the leachate. In batch assays, the grey waste produced a methane potential amounting to 70-85 % of the total methane potential of the grey waste plus putrescibles. In low moisture conditions, i.e. below 55%, methane production was delayed in the old landfill waste and prevented in the grey waste. In the emission potential study with five waste types, putrescibles produced 410 m{sup 3}CH{sub 4} tTS{sup -1} and 3.6 kgNH{sub 4}-N tTS{sup -1}, whereas composted putrescibles produced 41 m{sup 3}CH{sub 4} tVS{sup -1}, and 2.0 kgNH{sub 4}-N tTS{sup -1}. The remains of putrescibles probably caused the leaching potential of 2.1 kgNH{sub 4}-N tTS{sup -1} in the grey waste. Aeration for 51 days in lysimeters reduced the CH{sub 4} potential of putrescibles by more than 68 % and of the lysimeter landfilled grey waste by 50 %, indicating the potential of aeration for CH4 emission reduction. Nitrogen removal of landfill leachate was studied in the laboratory as well as on-site. Over 90 % nitrification of leachate was obtained with loading rates between 100 and 130 mgNH{sub 4}-N l{sup -1} d-1 at 25 deg C. Nitrified leachate was denitrified with a

High rate monitoring CH4 production dynamics and their link with behavioral phases in cattle

OpenAIRE

Blaise, Yannick; Lebeau, Frédéric; Andriamandroso, Andriamasinoro; Beckers, Yves; Heinesch, Bernard; Bindelle, Jérôme

2016-01-01

Microbial fermentation in the rumen produces methane (CH4) which is a loss of energy for ruminants and also contributes to global warming. While the respiration chamber is the standard reference for CH4 emissions quantification, daily CH4 production dynamics can be measured only by steps of 30 min and measurements on pasture are impossible. The alternative method using SF6 as tracer gas can be applied for grazing animals but provides average CH4 production values over at least several hours, ...

Infrared Spectra and Optical Constants of Elusive Amorphous Methane

Science.gov (United States)

Gerakines, Perry A.; Hudson, Reggie L.

2015-01-01

New and accurate laboratory results are reported for amorphous methane (CH4) ice near 10 K for the study of the interstellar medium (ISM) and the outer Solar System. Near- and mid-infrared (IR) data, including spectra, band strengths, absorption coefficients, and optical constants, are presented for the first time for this seldom-studied amorphous solid. The apparent IR band strength near 1300 cm(exp -1) (7.69 micrometer) for amorphous CH4 is found to be about 33% higher than the value long used by IR astronomers to convert spectral observations of interstellar CH4 into CH4 abundances. Although CH4 is most likely to be found in an amorphous phase in the ISM, a comparison of results from various laboratory groups shows that the earlier CH4 band strength at 1300 cm(exp -1) (7.69 micrometer) was derived from IR spectra of ices that were either partially or entirely crystalline CH4 Applications of the new amorphous-CH4 results are discussed, and all optical constants are made available in electronic form.

Mangroves act as a small methane source: an investigation on 5 pathways of methane emissions from mangroves

Science.gov (United States)

Chen, H.; Peng, C.; Guan, W.; Liao, B.; Hu, J.

2017-12-01

The methane (CH4) source strength of mangroves is not well understood, especially for integrating all CH4 pathways. This study measured CH4 fluxes by five pathways (sediments, pneumatophores, water surface, leaves, and stems) from four typical mangrove forests in Changning River of Hainan Island, China, including Kandelia candel , Sonneratia apetala, Laguncularia racemosa and Bruguiera gymnoihiza-Bruguiera sexangula. The CH4 fluxes (mean ± SE) from sediments were 4.82 ± 1.46 mg CH4 m-2 h-1 for those without pneumatophores and 1.36 ± 0.17 mg CH4 m-2 h-1 for those with pneumatophores. Among the three communities with pneumatophores, S. apetala community had significantly greater emission rate than the other two. Pneumatophores in S. apetala were found to significantly decrease CH4 emission from sediments (P duck farming. Leaves of mangroves except for K. candel were a weak CH4 sink while stems a weak source. As a whole the 72 ha of mangroves in the Changning river basin emitted about 8.10 Gg CH4 yr-1 with a weighted emission rate of about 1.29 mg CH4 m-2 h-1, therefore only a small methane source to the atmosphere compared to other reported ones. Keywords: Greenhouse Gases; Biogeochemistry; Tropical ecosystems; Methane budget

Thermal Methane Conversion to Syngas Mediated by Rh1-Doped Aluminum Oxide Cluster Cations RhAl3O4.

Science.gov (United States)

Li, Ya-Ke; Yuan, Zhen; Zhao, Yan-Xia; Zhao, Chongyang; Liu, Qing-Yu; Chen, Hui; He, Sheng-Gui

2016-10-05

Laser ablation generated RhAl 3 O 4 + heteronuclear metal oxide cluster cations have been mass-selected using a quadrupole mass filter and reacted with CH 4 or CD 4 in a linear ion trap reactor under thermal collision conditions. The reactions have been characterized by state-of-the-art mass spectrometry and quantum chemistry calculations. The RhAl 3 O 4 + cluster can activate four C-H bonds of a methane molecule and convert methane to syngas, an important intermediate product in methane conversion to value-added chemicals. The Rh atom is the active site for activation of the C-H bonds of methane. The high electron-withdrawing capability of Rh atom is the driving force to promote the conversion of methane to syngas. The polarity of Rh oxidation state is changed from positive to negative after the reaction. This study has provided the first example of methane conversion to syngas by heteronuclear metal oxide clusters under thermal collision conditions. Furthermore, the molecular level origin has been revealed for the condensed-phase experimental observation that trace amounts of Rh can promote the participation of lattice oxygen of chemically very inert support (Al 2 O 3 ) to oxidize methane to carbon monoxide.

UAV Remote Sensing Can Reveal the Effects of Low-Impact Seismic Lines on Surface Morphology, Hydrology, and Methane (CH4) Release in a Boreal Treed Bog

Science.gov (United States)

Lovitt, J.; Rahman, M. M.; Saraswati, S.; McDermid, G. J.; Strack, M.; Xu, B.

2018-03-01

Peatlands are globally significant stores of soil carbon, where local methane (CH4) emissions are strongly linked to water table position and microtopography. Historically, these factors have been difficult to measure in the field, constraining our capacity to observe local patterns of variability. In this paper, we show how remote sensing surveys conducted from unmanned aerial vehicle (UAV) platforms can be used to map microtopography and depth to water over large areas with good accuracy, paving the way for spatially explicit estimates of CH4 emissions. This approach enabled us to observe—for the first time—the effects of low-impact seismic lines (LIS; petroleum exploration corridors) on surface morphology and CH4 emissions in a treed-bog ecosystem in northern Alberta, Canada. Through compaction, LIS lines were found to flatten the observed range in microtopographic elevation by 46 cm and decrease mean depth to water by 15.4 cm, compared to surrounding undisturbed conditions. These alterations are projected to increase CH4 emissions by 20-120% relative to undisturbed areas in our study area, which translates to a total rise of 0.011-0.027 kg CH4 day-1 per linear kilometer of LIS ( 2 m wide). The 16 km of LIS present at our 61 ha study site were predicted to boost CH4 emissions by 20-70 kg between May and September 2016.

In-operando elucidation of bimetallic CoNi nanoparticles during high-temperature CH 4 /CO 2 reaction

KAUST Repository

Al-Sabban, Bedour E.; Falivene, Laura; Kozlov, Sergey M.; Aguilar Tapia, Antonio; Ould-Chikh, Samy; Hazemann, Jean-Louis; Cavallo, Luigi; Basset, Jean-Marie; Takanabe, Kazuhiro

2017-01-01

Dry reforming of methane (DRM) proceeds via CH4 decomposition to leave surface carbon species, followed by their removal with CO2-derived species. Reactivity tuning for stoichiometric CH4/CO2 reactants was attempted by alloying the non-noble metals

Phase equilibrium measurements of (methane + benzene) and (methane + methylbenzene) at temperatures from (188 to 348) K and pressures to 13 MPa

International Nuclear Information System (INIS)

Hughes, Thomas J.; Kandil, Mohamed E.; Graham, Brendan F.; Marsh, Kenneth N.; Huang, Stanley H.; May, Eric F.

2015-01-01

Highlights: • VLE data for (CH 4 (1) + C 6 H 6 (2)) and (CH 4 (1) + C 6 H 5 CH 3 (3)) were measured. • LLE was observed at T = 198.15 K, a T higher than expected, for (CH 4 + C 6 H 5 CH 3 ) . • Inconsistences in the literature data were identified and assessed. • More data at x 1 > 0.3 for both systems are needed to investigate discrepancies. - Abstract: New isothermal pTxy data are reported for (methane + benzene) and (methane + methylbenzene (toluene)) at pressures up to 13 MPa over the temperature range (188 to 313) K using a custom-built (vapor + liquid) equilibrium (VLE) apparatus. The aim of this work was to investigate literature data inconsistencies and to extend the measurements to lower temperatures. For (methane (1) + benzene (2)), measurements were made along six isotherms from (233 to 348) K at pressures to 9.6 MPa. At temperatures below 279 K there was evidence of a solid phase, and thus only vapor phase samples were analyzed at these temperatures. For the (methane (1) + methylbenzene (3)) system, measurements were made along seven isotherms from T = (188 to 313) K at pressures up to 13 MPa. Along the 198 K isotherm, a significant change in the data’s p,x slope was observed indicating (liquid + liquid) equilibria at higher pressures. The data were compared with literature data and with calculations made using the Peng–Robinson (PR) equation of state (EOS). For both binary systems our data agree with much of the literature data that also deviate from the EOS in a similar manner. However, the data of Elbishlawi and Spencer (1951) for both binary systems, which appear to have received an equal weighting to other data in the EOS development, are inconsistent with the results of our measurements and data from other literature sources

Effect of interannual variation in winter vertical mixing on CH4 dynamics in a subtropical reservoir

Science.gov (United States)

Itoh, Masayuki; Kobayashi, Yuki; Chen, Tzong-Yueh; Tokida, Takeshi; Fukui, Manabu; Kojima, Hisaya; Miki, Takeshi; Tayasu, Ichiro; Shiah, Fuh-Kwo; Okuda, Noboru

2015-07-01

Although freshwaters are considered to be substantial natural sources of atmospheric methane (CH4), in situ processes of CH4 production and consumption in freshwater ecosystems are poorly understood, especially in subtropical areas, leading to uncertainties in the estimation of global CH4 emissions. To improve our understanding of physical and biogeochemical factors affecting CH4 dynamics in subtropical lakes, we examined vertical and seasonal profiles of dissolved CH4 and its carbon isotope ratio (δ13C) and conducted incubation experiments to assess CH4 production and oxidation in the deep subtropical Fei-Tsui Reservoir (FTR; Taiwan). The mixing pattern of the FTR is essentially monomixis, but the intensity of winter vertical mixing changes with climatic conditions. In years with incomplete vertical mixing (does not reach the bottom) and subsequent strong thermal stratification resulting in profundal hypoxia, we observed increases in sedimentary CH4 production and thus profundal CH4 storage with the development of reducing conditions. In contrast, in years with strong winter vertical mixing to the bottom of the reservoir, CH4 production was suppressed under NO3--rich conditions, during which denitrifiers have the competitive advantage over methanogens. Diffusive emission from profundal CH4 storage appeared to be negligible due to the efficiency of CH4 oxidation during ascent through methane-oxidizing bacteria (MOB) activity. Most of the profundal CH4 was rapidly oxidized by MOB in both oxic and anoxic layers, as characterized by its carbon isotope signature. In contrast, aerobic CH4 production in the subsurface layer, which may be enhanced under high temperatures in summer, may account for a large portion of atmospheric CH4 emissions from this reservoir. Our CH4 profiling results provide valuable information for future studies predicting CH4 emissions from subtropical lakes with the progress of global warming.

Methane emissions in Danish riparian wetlands

DEFF Research Database (Denmark)

Audet, Joachim; Johansen, Jan Ravn; Andersen, Peter Mejlhede

2013-01-01

The present study was conducted to (i) investigate parameters influencing the fluxes of the greenhouse gas methane (CH4) in Danish riparian wetlands with contrasting vegetation characteristics and (ii) develop models relating CH4 emissions to soil and/or vegetation parameters integrating the spat......The present study was conducted to (i) investigate parameters influencing the fluxes of the greenhouse gas methane (CH4) in Danish riparian wetlands with contrasting vegetation characteristics and (ii) develop models relating CH4 emissions to soil and/or vegetation parameters integrating...

Influence of vehicular emissions on atmospheric CH4 and NMHC mixing ratios and its correlation with CO and other VOCs tracers in Mexico City

Science.gov (United States)

Solano-Murillo, M.; Torres-Jardón, R.; Ruiz-Suárez, L. G.; Barrera-Huertas, H.; Hernandez-Solis, J. M.

2016-12-01

The Mexico City Metropolitan Area (MCMA) is one of the world's largest and most polluted urban areas. A recent GHC emission inventory for MCMA suggests that vehicular emissions contribute with around 37% of CH4, followed by landfills and dump garbage areas (30%) and construction and manufacturing (27%). Contrary to other urban areas, natural gas is not the main fuel used in MCMA, neither for domestic and industrial heating, nor for transportation. Therefore, there is a great uncertainty about who is the main contributor of CH4 emissions. An intensive monitoring campaign of methane (CH4), Non-methane hydrocarbons (NMHC) and carbon monoxide (CO) was performed between February and March 2015 in southwest MCMA. Methane concentrations showed sometimes a diurnal pattern similar to those of CO and to NMHC but most of the time this similarity was lost (CH4 vs CO, R2 = 0.27; CH4 vs NMHC, R2 = 0.28). However, NMHC correlated well with CO (R2 = 0.75). The intercepts of the CH4-CO correlation resulted in [CH4] 1.8 ppm and that of the CO-NMHC correlation in [CO] 0.080 ppb. The lack of agreement between CH4 and CO indicates these species do not come from the same sources. The results suggest that vehicular emissions are not significant contributors to atmospheric CH4 and that the background methane concentration has not change significantly in 25 years. An attempt to correlate some tracers COVs tracers of vehicular and biomass burning with CH4, NMHC and CH4 is done.

Methane-free biogas for direct feeding of solid oxide fuel cells

Science.gov (United States)

Leone, P.; Lanzini, A.; Santarelli, M.; Calì, M.; Sagnelli, F.; Boulanger, A.; Scaletta, A.; Zitella, P.

This paper deals with the experimental analysis of the performance and degradation issues of a Ni-based anode-supported solid oxide fuel cell fed by a methane-free biogas from dark-anaerobic digestion of wastes by pastry and fruit shops. The biogas is produced by means of an innovative process where the biomass is fermented with a pre-treated bacteria inoculum (Clostridia) able to completely inhibit the methanization step during the fermentation process and to produce a H 2/CO 2 mixture instead of conventional CH 4/CO 2 anaerobic digested gas (bio-methane). The proposed biogas production route leads to a biogas composition which avoids the need of introducing a reformer agent into or before the SOFC anode in order to reformate it. In order to analyse the complete behaviour of a SOFC with the bio-hydrogen fuel, an experimental session with several H 2/CO 2 synthetic mixtures was performed on an anode-supported solid oxide fuel cell with a Ni-based anode. It was found that side reactions occur with such mixtures in the typical thermodynamic conditions of SOFCs (650-800 °C), which have an effect especially at high currents, due to the shift to a mixture consisting of hydrogen, carbon monoxide, carbon dioxide and water. However, cells operated with acceptable performance and carbon deposits (typical of a traditional hydrocarbon-containing biogas) were avoided after 50 h of cell operation even at 650 °C. Experiments were also performed with traditional bio-methane from anaerobic digestion with 60/40 vol% of composition. It was found that the cell performance dropped after few hours of operation due to the formation of carbon deposits. A short-term test with the real as-produced biogas was also successfully performed. The cell showed an acceptable power output (at 800 °C, 0.35 W cm -2 with biogas, versus 0.55 W cm -2 with H 2) although a huge quantity of sulphur was present in the feeding fuel (hydrogen sulphide at 103 ppm and mercaptans up to 10 ppm). Therefore, it

Methane-free biogas for direct feeding of solid oxide fuel cells

Energy Technology Data Exchange (ETDEWEB)

Leone, P.; Lanzini, A.; Santarelli, M.; Cali, M. [Dipartimento di Energetica, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Turin (Italy); Sagnelli, F.; Boulanger, A.; Scaletta, A.; Zitella, P. [BioEnergy Lab, Environment Park S.p.A., Via Livorno 60, 10144 Turin (Italy)

2010-01-01

This paper deals with the experimental analysis of the performance and degradation issues of a Ni-based anode-supported solid oxide fuel cell fed by a methane-free biogas from dark-anaerobic digestion of wastes by pastry and fruit shops. The biogas is produced by means of an innovative process where the biomass is fermented with a pre-treated bacteria inoculum (Clostridia) able to completely inhibit the methanization step during the fermentation process and to produce a H{sub 2}/CO{sub 2} mixture instead of conventional CH{sub 4}/CO{sub 2} anaerobic digested gas (bio-methane). The proposed biogas production route leads to a biogas composition which avoids the need of introducing a reformer agent into or before the SOFC anode in order to reformate it. In order to analyse the complete behaviour of a SOFC with the bio-hydrogen fuel, an experimental session with several H{sub 2}/CO{sub 2} synthetic mixtures was performed on an anode-supported solid oxide fuel cell with a Ni-based anode. It was found that side reactions occur with such mixtures in the typical thermodynamic conditions of SOFCs (650-800 C), which have an effect especially at high currents, due to the shift to a mixture consisting of hydrogen, carbon monoxide, carbon dioxide and water. However, cells operated with acceptable performance and carbon deposits (typical of a traditional hydrocarbon-containing biogas) were avoided after 50 h of cell operation even at 650 C. Experiments were also performed with traditional bio-methane from anaerobic digestion with 60/40 vol% of composition. It was found that the cell performance dropped after few hours of operation due to the formation of carbon deposits. A short-term test with the real as-produced biogas was also successfully performed. The cell showed an acceptable power output (at 800 C, 0.35 W cm{sup -2} with biogas, versus 0.55 W cm{sup -2} with H{sub 2}) although a huge quantity of sulphur was present in the feeding fuel (hydrogen sulphide at 103 ppm and

Methane reacts with heteropolyacids chemisorbed on silica to produce acetic acid under soft conditions

KAUST Repository

Sun, Miao

2013-01-16

Selective functionalization of methane at moderate temperature is of crucial economic, environmental, and scientific importance. Here, we report that methane reacts with heteropolyacids (HPAs) chemisorbed on silica to produce acetic acid under soft conditions. Specially, when chemisorbed on silica, H 4SiW12O40, H3PW12O 40, H4SiMo12O40, and H 3PMo12O40 activate the primary C-H bond of methane at room temperature and atmospheric pressure. With these systems, acetic acid is produced directly from methane, in a single step, in the absence of Pd and without adding CO. Extensive surface characterization by solid-state NMR spectroscopy, IR spectroscopy, cyclic voltammetry, and X-ray photoelectron spectroscopy suggests that C-H activation of methane is triggered by the protons in the HPA-silica interface with concerted reduction of the Keggin cage, leading to water formation and hydration of the interface. This is the simplest and mildest way reported to date to functionalize methane. © 2012 American Chemical Society.

Effects of the conversion of cropland to forest on the CH4 oxidation capacity in soils.

Science.gov (United States)

Bárcena, Teresa G.; D'Imperio, Ludovica; Priemé, Anders; Gundersen, Per; Vesterdal, Lars; Christiansen, Jesper R.

2013-04-01

As the second most important greenhouse gas (GHG) in the atmosphere, methane (CH4) plays a central role in global warming. Diverse types of soil have been reported as potential CH4 sinks due to the activity of methane oxidizing bacteria (MOB), underlining the importance of this functional group of microorganisms on a global basis. Agricultural practices are known to negatively affect CH4 oxidation in soil, while afforestation of former agricultural soils has been shown to enhance CH4 oxidation over time. However, knowledge is scarce with regard to the mechanisms driving the process of CH4 oxidation in different land uses. Our aim was to study the changes in CH4 uptake capacity in soils along a land-use change gradient from cropland to forest. We performed an incubation experiment to study the CH4 oxidation capacity of the top mineral soil (0-5 cm and 5-15 cm depth) for sites representing the transition from agriculture to afforestation based on monoculture of three tree species with different stand ages: pedunculate oak (4, 19, 42 and >200 years old), European larch (22 and 41 years old) and Norway spruce (15 and 43 years old). Main soil parameters were also measured to determine differences in soil properties between sites. Methane oxidation rates were related to the abundance of the soil methanotrophic community based on quantitative PCR (qPCR). In addition, we also estimated the abundance of ammonia-oxidizing bacteria (AOB) and archaea (AOA), in order to investigate the link between these two similar functional groups. Although present, the abundance of AOB was under detection limit. The effects and interactions among all measured variables were summarized by Principal Component Analysis (PCA). Along the gradient, CH4 oxidation increased with increasing stand age in both soil layers (ranging from 0-1.3 nmol g-1dw d-1). However, we detected significant differences, in particular between oak and spruce, suggesting a possible tree species effect on the CH4

Adsorption of CH{sub 4} on nitrogen- and boron-containing carbon models of coal predicted by density-functional theory

Energy Technology Data Exchange (ETDEWEB)

Liu, Xiao-Qiang [College of Chemistry, Key Lab of Green Chemistry and Technology in Ministry of Education, Sichuan University, Chengdu 610064 (China); Xue, Ying, E-mail: yxue@scu.edu.cn [College of Chemistry, Key Lab of Green Chemistry and Technology in Ministry of Education, Sichuan University, Chengdu 610064 (China); Tian, Zhi-Yue; Mo, Jing-Jing; Qiu, Nian-Xiang [College of Chemistry, Key Lab of Green Chemistry and Technology in Ministry of Education, Sichuan University, Chengdu 610064 (China); Chu, Wei [Department of Chemical Engineering, Sichuan University, Chengdu 610065 (China); Xie, He-Ping [Key Laboratory of Energy Engineering Safety and Mechanics on Disasters, The Ministry of Education, Sichuan University, Chengdu 610065 (China)

2013-11-15

Graphene doped by nitrogen (N) and/or boron (B) is used to represent the surface models of coal with the structural heterogeneity. Through the density functional theory (DFT) calculations, the interactions between coalbed methane (CBM) and coal surfaces have been investigated. Several adsorption sites and orientations of methane (CH{sub 4}) on graphenes were systematically considered. Our calculations predicted adsorption energies of CH{sub 4} on graphenes of up to −0.179 eV, with the strongest binding mode in which three hydrogen atoms of CH{sub 4} direct to graphene surface, observed for N-doped graphene, compared to the perfect (−0.154 eV), B-doped (−0.150 eV), and NB-doped graphenes (−0.170 eV). Doping N in graphene increases the adsorption energies of CH{sub 4}, but slightly reduced binding is found when graphene is doped by B. Our results indicate that all of graphenes act as the role of a weak electron acceptor with respect to CH{sub 4}. The interactions between CH{sub 4} and graphenes are the physical adsorption and slightly depend upon the adsorption sites on graphenes and the orientations of methane as well as the electronegativity of dopant atoms in graphene.

Quantifying the relative contribution of natural gas fugitive emissions to total methane emissions in Colorado and Utah using mobile stable isotope (13CH4) analysis

Science.gov (United States)

Rella, Chris; Jacobson, Gloria; Crosson, Eric; Karion, Anna; Petron, Gabrielle; Sweeney, Colm

2013-04-01

Fugitive emissions of methane into the atmosphere are a major concern facing the natural gas production industry. Because methane is more energy-rich than coal per kg of CO2 emitted into the atmosphere, it represents an attractive alternative to coal for electricity generation. However, given that the global warming potential of methane is many times greater than that of carbon dioxide (Solomon et al. 2007), the importance of quantifying the fugitive emissions of methane throughout the natural gas production and distribution process becomes clear (Howarth et al. 2011). A key step in the process of assessing the emissions arising from natural gas production activities is partitioning the observed methane emissions between natural gas fugitive emissions and other sources of methane, such as from landfills or agricultural activities. One effective method for assessing the contribution of these different sources is stable isotope analysis. In particular, the 13CH4 signature of natural gas (-35 to -40 permil) is significantly different that the signature of other significant sources of methane, such as landfills or ruminants (-45 to -70 permil). In this paper we present measurements of mobile field 13CH4 using a spectroscopic stable isotope analyzer based on cavity ringdown spectroscopy, in two intense natural gas producing regions of the United States: the Denver-Julesburg basin in Colorado, and the Uintah basin in Utah. Mobile isotope measurements in the nocturnal boundary layer have been made, over a total path of 100s of km throughout the regions, allowing spatially resolved measurements of the regional isotope signature. Secondly, this analyzer was used to quantify the isotopic signature of those individual sources (natural gas fugitive emissions, concentrated animal feeding operations, and landfills) that constitute the majority of methane emissions in these regions, by making measurements of the isotope ratio directly in the downwind plume from each source. These

Estimation of methane emissions from slurry pits under pig and cattle confinements

DEFF Research Database (Denmark)

Petersen, Søren O.; Olsen, Anne B.; Elsgaard, Lars

2016-01-01

Quantifying in-house emissions of methane (CH4) from liquid manure (slurry) is difficult due to high background emissions from enteric processes, yet of great importance for correct estimation of CH4 emissions from manure management and effects of treatment Technologies such as anaerobic digestion...... less sensitive to uncertainties in VSd or slurry temperature. A model application indicated that losses of carbon in VS as CO2 may be much greater than losses as CH4. Implications of these results for the correct estimation of CH4 emissions from manure management, and for the mitigation potential...... and cattle slurry differed significantly at 0.030 and 0.011 kg CH4 kg-1 VS (volatile solids). Current estimates of CH4 emissions from pig and cattle manure management correspond to 0.032 and 0.015 kg CH4 kg-1, respectively, indicating that slurry pits under animal confinements are a significant source...

Aviation NOx-induced CH4 effect: Fixed mixing ratio boundary conditions versus flux boundary conditions

Science.gov (United States)

Khodayari, Arezoo; Olsen, Seth C.; Wuebbles, Donald J.; Phoenix, Daniel B.

2015-07-01

Atmospheric chemistry-climate models are often used to calculate the effect of aviation NOx emissions on atmospheric ozone (O3) and methane (CH4). Due to the long (∼10 yr) atmospheric lifetime of methane, model simulations must be run for long time periods, typically for more than 40 simulation years, to reach steady-state if using CH4 emission fluxes. Because of the computational expense of such long runs, studies have traditionally used specified CH4 mixing ratio lower boundary conditions (BCs) and then applied a simple parameterization based on the change in CH4 lifetime between the control and NOx-perturbed simulations to estimate the change in CH4 concentration induced by NOx emissions. In this parameterization a feedback factor (typically a value of 1.4) is used to account for the feedback of CH4 concentrations on its lifetime. Modeling studies comparing simulations using CH4 surface fluxes and fixed mixing ratio BCs are used to examine the validity of this parameterization. The latest version of the Community Earth System Model (CESM), with the CAM5 atmospheric model, was used for this study. Aviation NOx emissions for 2006 were obtained from the AEDT (Aviation Environmental Design Tool) global commercial aircraft emissions. Results show a 31.4 ppb change in CH4 concentration when estimated using the parameterization and a 1.4 feedback factor, and a 28.9 ppb change when the concentration was directly calculated in the CH4 flux simulations. The model calculated value for CH4 feedback on its own lifetime agrees well with the 1.4 feedback factor. Systematic comparisons between the separate runs indicated that the parameterization technique overestimates the CH4 concentration by 8.6%. Therefore, it is concluded that the estimation technique is good to within ∼10% and decreases the computational requirements in our simulations by nearly a factor of 8.

Methane oxidation and attenuation of sulphur compounds in landfill top cover systems: Lab-scale tests.

Science.gov (United States)

Raga, Roberto; Pivato, Alberto; Lavagnolo, Maria Cristina; Megido, Laura; Cossu, Raffaello

2018-03-01

In this study, a top cover system is investigated as a control for emissions during the aftercare of new landfills and for old landfills where biogas energy production might not be profitable. Different materials were studied as landfill cover system in lab-scale columns: mechanical-biological pretreated municipal solid waste (MBP); mechanical-biological pretreated biowaste (PB); fine (PBS f ) and coarse (PBS c ) mechanical-biological pretreated mixtures of biowaste and sewage sludge, and natural soil (NS). The effectiveness of these materials in removing methane and sulphur compounds from a gas stream was tested, even coupled with activated carbon membranes. Concentrations of CO 2 , CH 4 , O 2 , N 2 , H 2 S and mercaptans were analysed at different depths along the columns. Methane degradation was assessed using mass balance and the results were expressed in terms of methane oxidation rate (MOR). The highest maximum and mean MOR were observed for MBP (17.2gCH 4 /m 2 /hr and 10.3gCH 4 /m 2 /hr, respectively). Similar values were obtained with PB and PBS c . The lowest values of MOR were obtained for NS (6.7gCH 4 /m 2 /hr) and PBS f (3.6gCH 4 /m 2 /hr), which may be due to their low organic content and void index, respectively. Activated membranes with high load capacity did not seem to have an influence on the methane oxidation process: MBP coupled with 220g/m 2 and 360g/m 2 membranes gave maximum MOR of 16.5gCH 4 /m 2 /hr and 17.4gCH 4 /m 2 /hr, respectively. Activated carbon membranes proved to be very effective on H 2 S adsorption. Furthermore, carbonyl sulphide, ethyl mercaptan and isopropyl mercaptan seemed to be easily absorbed by the filling materials. Copyright © 2017. Published by Elsevier B.V.

Investigation of methane steam reforming in planar porous support of solid oxide fuel cell

International Nuclear Information System (INIS)

Yang Yongping; Du Xiaoze; Yang Lijun; Huang Yuan; Xian Haizhen

2009-01-01

Adopting the porous support in integrated-planar solid oxide fuel cell (IP-SOFC) can reduce the operating temperature by reducing thickness of electrolyte layer, and also, provide internal reforming environment for hydrogen-rich fuel gas. The distributions of reactant and product components, and temperature of methane steam reforming for IP-SOFC were investigated by the developed physical and mathematical model with thermodynamic analysis, in which eleven possible reaction mechanisms were considered by the source terms and Arrhenius relationship. Numerical simulation of the model revealed that the progress of reforming reaction and the distribution of the product, H 2 , were influenced by the operating conditions, included that of temperature, ratio of H 2 O and CH 4 , as well as by the porosity of the supporting material. The simulating results indicate that the methane conversion rate can reach its maximum value under the operating temperature of 800 deg. C and porosity of ε = 0.4, which rather approximate to the practical operating conditions of IP-SOFC. In addition, characteristics of carbon deposition on surface of catalyst were discussed under various operating conditions and configuration parameters of the porous support. The present works provided some theoretical explanations to the numerous experimental observations and engineered practices

Vibrational transition moments of CH4 from first principles

Science.gov (United States)

Yurchenko, Sergei N.; Tennyson, Jonathan; Barber, Robert J.; Thiel, Walter

2013-09-01

New nine-dimensional (9D), ab initio electric dipole moment surfaces (DMSs) of methane in its ground electronic state are presented. The DMSs are computed using an explicitly correlated coupled cluster CCSD(T)-F12 method in conjunction with an F12-optimized correlation consistent basis set of the TZ-family. A symmetrized molecular bond representation is used to parameterise these 9D DMSs in terms of sixth-order polynomials. Vibrational transition moments as well as band intensities for a large number of IR-active vibrational bands of 12CH4 are computed by vibrationally averaging the ab initio dipole moment components. The vibrational wavefunctions required for these averages are computed variationally using the program TROVE and a new ‘spectroscopic’ 12CH4 potential energy surface. The new DMSs will be used to produce a hot line list for 12CH4.

Assessing methane oxidation under landfill covers and its contribution to the above atmospheric CO2 levels: The added value of the isotope (δ13C and δ18O CO2; δ13C and δD CH4) approach

International Nuclear Information System (INIS)

Widory, D.; Proust, E.; Bellenfant, G.; Bour, O.

2012-01-01

Highlights: ► Comparison of the isotope and mass balance approaches to evaluate the level of methane oxidation within a landfill. ► The level of methane oxidation is not homogenous under the landfill cover and is strongly correlated to the methane flux. ► Isotope tracking of the contribution of the methane oxidation to the CO 2 concentrations in the ambient air. - Abstract: We are presenting here a multi-isotope approach (δ 13 C and δ 18 O of CO 2 ; δ 13 C and δD of CH 4 ) to assess (i) the level(s) of methane oxidation during waste biodegradation and its migration through a landfill cover in Sonzay (France), and (ii) its contribution to the atmospheric CO 2 levels above the surface. The isotope approach is compared to the more conventional mass balance approach. Results from the two techniques are comparable and show that the CH 4 oxidation under the landfill cover is heterogenous, with low oxidation percentages in samples showing high biogas fluxes, which was expected in clay covers presenting fissures, through which CH 4 is rapidly transported. At shallow depth, more immobile biogas pockets show a higher level of CH 4 oxidation by the methanotrophic bacteria. δ 13 C of CO 2 samples taken at different heights (from below the cover up to 8 m above the ground level) were also used to identify and assess the relative contributions of its main sources both under the landfill cover and in the surrounding atmosphere.

Investigating the emission, dissolution, and oxidation of CH4 within and around a seep bubble plume in the Gulf of Mexico.

Science.gov (United States)

Leonte, M.; Kessler, J. D.; Socolofsky, S. A.

2016-02-01

One of the largest carbon reservoirs on the planet is stored as methane (CH4) in and below the seafloor. However, a large discrepancy exists between estimated fluxes of CH4 into the water column and CH4 fluxes from the sea surface to the atmosphere, suggesting that a significant fraction of CH4 released from seafloor seeps is dissolved and potentially removed through microbial oxidation. Here we present data investigating the fate of CH4 released from the Sleeping Dragon seep site in the Gulf of Mexico. The bubble plume was followed from the seafloor until it fully dissolved using a remotely operated vehicle (ROV). Water samples were collected by the ROV at different depths as well as lateral transects through the bubble plume. These samples were analyzed for dissolved concentrations of methane, ethane, propane, and butane as well as the 13C isotopic ratio of methane. Furthermore, seep bubbles from the seafloor were also collected and analyzed for the same properties. Based on these chemical data, the rate of CH4 emission from the seafloor, oxidation in the water column, and dissolution are investigated.

Electrode design for direct-methane micro-tubular solid oxide fuel cell (MT-SOFC)

Science.gov (United States)

Rabuni, Mohamad Fairus; Li, Tao; Punmeechao, Puvich; Li, Kang

2018-04-01

Herein, a micro-structured electrode design has been developed via a modified phase-inversion method. A thin electrolyte integrated with a highly porous anode scaffold has been fabricated in a single-step process and developed into a complete fuel cell for direct methane (CH4) utilisation. A continuous and well-dispersed layer of copper-ceria (Cu-CeO2) was incorporated inside the micro-channels of the anode scaffold. A complete cell was investigated for direct CH4 utilisation. The well-organised micro-channels and nano-structured Cu-CeO2 anode contributed to an increase in electrochemical reaction sites that promoted charge-transfer as well as facilitating gaseous fuel distribution, resulting in outstanding performances. Excellent electrochemical performances have been achieved in both hydrogen (H2) and CH4 operation. The power density of 0.16 Wcm-2 at 750 °C with dry CH4 as fuel is one of the highest ever reported values for similar anode materials.

Methane and carbon dioxide ratio in excreted air for quantification of the methane production from ruminants

DEFF Research Database (Denmark)

Madsen, Jørgen; Bjerg, Bjarne Schmidt; Hvelplund, Torben

2010-01-01

This technical note presents a simple, fast, reliable and cheap method to estimate the methane (CH4) production from animals by using the CH4 and carbon dioxide (CO2) concentrations in air near the animals combined with an estimation of the total CO2 production from information on intake of metab......This technical note presents a simple, fast, reliable and cheap method to estimate the methane (CH4) production from animals by using the CH4 and carbon dioxide (CO2) concentrations in air near the animals combined with an estimation of the total CO2 production from information on intake...

Methane and hydrogen production from crop biomass through anaerobic digestion

Energy Technology Data Exchange (ETDEWEB)

Pakarinen, O.

2011-07-01

The feasibility of methane and hydrogen production from energy crops through anaerobic digestion was evaluated in this thesis. The effects of environmental conditions, e.g. pH and temperature, as well as inoculum source on H{sub 2} yield were studied in batch assays. In addition, the effects of pre-treatments on methane and hydrogen yield as well as the feasibility of two-stage H{sub 2} + CH{sub 4} production was evaluated. Moreover, the effect of storage on methane yield of grasses was evaluated. Monodigestion of grass silage for methane production was studied, as well as shifting the methanogenic process to hydrogenic. Hydrogen production from grass silage and maize was shown to be possible with heat-treated inoculum in batch assays, with highest H{sub 2} yields of 16.0 and 9.9 ml gVS{sub added}-1 from untreated grass silage and maize, respectively. Pre-treatments (NaOH, HCl and water-extraction) showed some potential in increasing H{sub 2} yields, while methane yields were not affected. Two-stage H{sub 2} + CH{sub 4} producing process was shown to improve CH{sub 4} yields when compared to traditional one-stage CH{sub 4} process. Methane yield from grass silage monodigestion in continuously stirred tank reactor (CSTR) with organic loading rate (OLR) of 2 kgVS (m3d)-1 and hydraulic retention time (HRT) of 30 days was at most 218 l kgVS{sub fed}-1. Methanogenic process was shifted to hydrogenic by increasing the OLR to 10 kgVS (m3d)-1 and shortening the HRT to 6 days. Highest H{sub 2} yield from grass silage was 42 l kgVS{sub fed}-1 with a maximum H{sub 2} content of 24 %. Energy crops can be successfully stored even for prolonged periods without decrease in methane yield. However, under sub-optimal storage conditions loss in volatile solids (VS) content and methane yield can occur. According to present results energy crops such as grass silage and maize can be converted to hydrogen or methane in AD process. Hydrogen energy yields are typically only 2-5 % of the

Kinetics of Methane Production from Swine Manure and Buffalo Manure.

Science.gov (United States)

Sun, Chen; Cao, Weixing; Liu, Ronghou

2015-10-01

The degradation kinetics of swine and buffalo manure for methane production was investigated. Six kinetic models were employed to describe the corresponding experimental data. These models were evaluated by two statistical measurements, which were root mean square prediction error (RMSPE) and Akaike's information criterion (AIC). The results showed that the logistic and Fitzhugh models could predict the experimental data very well for the digestion of swine and buffalo manure, respectively. The predicted methane yield potential for swine and buffalo manure was 487.9 and 340.4 mL CH4/g volatile solid (VS), respectively, which was close to experimental values, when the digestion temperature was 36 ± 1 °C in the biochemical methane potential assays. Besides, the rate constant revealed that swine manure had a much faster methane production rate than buffalo manure.

Dissolved methane in the Beaufort Sea and the Arctic Ocean, 1992-2009; sources and atmospheric flux

Science.gov (United States)

Lorenson, Thomas D.; Greinert, Jens; Coffin, Richard B.

2016-01-01

Methane concentration and isotopic composition was measured in ice-covered and ice-free waters of the Arctic Ocean during eleven surveys spanning the years of 1992-1995 and 2009. During ice-free periods, methane flux from the Beaufort shelf varies from 0.14 to 0.43 mg CH4 m-2 day-1. Maximum fluxes from localized areas of high methane concentration are up to 1.52 mg CH4 m-2 day-1. Seasonal buildup of methane under ice can produce short-term fluxes of methane from the Beaufort shelf that varies from 0.28 to 1.01 to mg CH4 m-2 day-1. Scaled-up estimates of minimum methane flux from the Beaufort Sea and pan-Arctic shelf for both ice-free and ice-covered periods range from 0.02 Tg CH4 yr-1 and 0.30 Tg CH4 yr-1 respectively to maximum fluxes of 0.18 Tg CH4 yr-1 and 2.2 Tg CH4 yr-1 respectively. A methane flux of 0.36 Tg CH4 yr-1from the deep Arctic Ocean was estimated using data from 1993-94. The flux can be as much as 2.35 Tg CH4 yr-1 estimated from maximum methane concentrations and wind speeds of 12 m/s, representing only 0.42% of the annual atmospheric methane budget of ~560 Tg CH4 yr-1. There were no significant changes in methane fluxes during the time period of this study. Microbial methane sources predominate with minor influxes from thermogenic methane offshore Prudhoe Bay and the Mackenzie River delta and may include methane from gas hydrate. Methane oxidation is locally important on the shelf and is a methane sink in the deep Arctic Ocean.

Potential for biohydrogen and methane production from olive pulp

DEFF Research Database (Denmark)

Gavala, Hariklia N.; Skiadas, Ioannis V.; Ahring, Birgitte Kiær

2005-01-01

The present study investigates the potential for thermophilic biohydrogen and methane production from olive pulp, which is the semi-solid residue coming from the two-phase processing of olives. It focussed on: a) production of methane from the raw olive pulp, b) anaerobic bio-production of hydrogen...... from the olive pulp, and c) subsequent anaerobic treatment of the hydrogen-effluent with the simultaneous production of methane. Both continuous and batch experiments were performed. The hydrogen potential of the olive pulp amounted to 1.6 mmole H-2 per g TS. The methane potential of the raw olive pulp...... and hydrogen-effluent was as high as 19 mmole CH4 per g TS. This suggests that olive pulp is an ideal substrate for methane production and it shows that biohydrogen production can be very efficiently coupled with a subsequent step for methane production....

Biogeochemical controls on microbial CH4 and CO2 production in Arctic polygon tundra

Science.gov (United States)

Zheng, J.

2016-12-01

Accurately simulating methane (CH4) and carbon dioxide (CO2) emissions from high latitude soils is critically important for reducing uncertainties in soil carbon-climate feedback predictions. The signature polygonal ground of Arctic tundra generates high level of heterogeneity in soil thermal regime, hydrology and oxygen availability, which limits the application of current land surface models with simple moisture response functions. We synthesized CH4 and CO2 production measurements from soil microcosm experiments across a wet-to dry permafrost degradation gradient from low-centered (LCP) to flat-centered (FCP), and high-centered polygons (HCP) to evaluate the relative importance of biogeochemical processes and their response to warming. More degraded polygon (HCP) showed much less carbon loss as CO2 or CH4, while the total CO2 production from FCP is comparable to that from LCP. Maximum CH4 production from the active layer of LCP was nearly 10 times that of permafrost and FCP. Multivariate analyses identifies gravimetric water content and organic carbon content as key predictors for CH4 production, and iron reduction as a key regulator of pH. The synthesized data are used to validate the geochemical model PHREEQC with extended anaerobic organic substrate turnover, fermentation, iron reduction, and methanogenesis reactions. Sensitivity analyses demonstrate that better representations of anaerobic processes and their pH dependency could significantly improve estimates of CH4 and CO2 production. The synthesized data suggest local decreases in CH4 production along the polygon degradation gradient, which is consistent with previous surface flux measurements. Methane oxidation occurring through the soil column of degraded polygons contributes to their low CH4 emissions as well.

Methane emissions from paddy cultivation and livestock farming in Sarawak, Malaysia

Directory of Open Access Journals (Sweden)

Peng E.K.

2017-01-01

Full Text Available In this study, implementation of Tier 1 methodology of 2006 IPCC (Intergovernmental Panel on Climate Change Guidelines in paddy cultivation and livestock farming has been applied to estimate methane emissions in Sarawak, Malaysia within the years from 1998 to 2009. Methane emission inventory has been developed in this study, based on volume 4, 2006 IPCC Guidelines. Based on cultivation area and livestock population data as input to Tier 1 methodology, variations in paddy cultivation area and amount of livestock has been identified as the main contributor to emissions of methane. Methane emissions increased from 1.61 to 1.72 Gg CH4/year during 1998 to 1999. Based on results obtained, the outcomes show that there would be a significant drop of methane emission from buffalo and sheep. Although there are gain and loss in emissions from enteric fermentation, drastic reduction is observed from 0.65 Gg CH4/year in 1998 to 0.44 Gg CH4/year in 2009 as well as 0.05 Gg CH4/year to 0.02 Gg CH4/year for buffalo and sheep respectively. Simultaneously, methane emissions from manure management of buffalo has decreased from 0.024 Gg CH4/year in 1998 to 0.016 Gg CH4/year in 2009 while for sheep, its emission from manure management dropped from 0.002 Gg CH4/year in 1998 to 0.0007 Gg CH4/year in 2009. Overall emission from paddy cultivation can be considered in upward trend due to gain from 1998 at 1.61 Gg CH4/year to 1.67 Gg CH4/year in 2009. As an addition, significant rise in methane emission by 0.24 Gg CH4/year from 2000 to 2006 as well as 0.1 Gg CH4/year from 2007 to 2009 show momentum gaining in enteric fermentation of cattle. It also indicates future increment in methane emission from cattle which coherently affects the state’s emission level. As for emissions from manure management, emissions from cattle, goat and deer are gaining momentum in Sarawak.

Correlations between substrate availability, dissolved CH₄, and CH₄ emissions in an arctic wetland subject to warming and plant removal

DEFF Research Database (Denmark)

Nielsen, Cecilie Skov; Michelsen, Anders; Strobel, Bjarne W.

2017-01-01

The Arctic is warming which may potentially affect substrate availability, organic matter decomposition, plant growth, and plant species composition. This may lead to changes in the exchange of methane (CH4) and carbon dioxide (CO2) between the soil system and the atmosphere. Yet the correlations...

Investigating CH4 production in an oxic plant-soil system -a new approach combining isotopic labelling (13C) and inhibitors

Science.gov (United States)

Lenhart, Katharina; Keppler, Frank

2017-04-01

Typically, aerated soil are net sinks of atmospheric methane (CH4), being highest in native ecosystems (pristine forests > managed forests > grasslands > crop fields). However, this does not exclude a simultaneous endogenic CH4 production in the plant-soil system, which cannot be detected simply via CH4 flux measurements. Methanogenic archaea producing CH4 under anoxic conditions were thought to be the only biotic source of CH4 in the soil. However, until recently a non-archaeal pathway of CH4 formation is known where CH4 is produced under oxic conditions in plants (Keppler et al. 2006) and fungi (Lenhart et al. 2012). Additionally, abiotic formation of CH4 from soil organic matter was reported (Jugold et al. 2012) and may be ubiquitous in terrestrial ecosystems. The major goal of this project was to determine soil endogenic CH4 sources and to estimate their contribution to the endogenic CH4 production. Especially the effect of plants and fungi on soil CH4 production was investigated. Therefore, a series of experiments was carried out on field fresh soil collected in a grassland and a forest ecosystem under controlled laboratory conditions. By combining selective inhibitors and 13C labelling, CH4 production rates of several CH4 sources were quantified. The major difficulty was to detect the comparatively small flux of CH4 production against the background of the high CH4 consumption rates due to methanotrophic bacteria. Therefore, we supplemented bare soil and soil with vegetation with selective inhibitors and 13C labelled substrates in a closed chamber system. In a first step, CH4 production was determined by the inhibition of CH4 oxidizing bacteria with Difluoromethane (DFM, 2ml l-1). In the following, a 13C labelled substrate (either CO2, Acetate, or Methionine -S-CH3 labelled) was added in combination with a specific inhibitor -either for archaeal methanogenesis (Bromoethanesulfonate), bacteria (Streptomycin), or fungi (Captan, Cycloheximide). Gas samples were

Trace methane oxidation and the methane dependency of sulfate reduction in anaerobic granular sludge

KAUST Repository

Meulepas, Roel J.W.; Jagersma, Christian G.; Zhang, Yu; Petrillo, Michele; Cai, Hengzhe; Buisman, Cees J.N.; Stams, Alfons J.M.; Lens, Piet N.L.

2010-01-01

This study investigates the oxidation of labeled methane (CH4) and the CH4 dependence of sulfate reduction in three types of anaerobic granular sludge. In all samples, 13C-labeled CH4 was anaerobically oxidized to 13C-labeled CO2, while net

Anaerobic methane oxidation rates at the sulfate-methane transition in marine sediments from Kattegat and Skagerrak (Denmark)

International Nuclear Information System (INIS)

Iversen, N.; Jorgensen, B.B.

1985-01-01

Concomitant radiotracer measurements were made of in situ rates of sulfate reduction and anaerobic methane oxidation in 2-3-m-long sediment cores. Methane accumulated to high concentrations (> 1 mM CH 4 ) only below the sulfate zone, at 1 m or deeper in the sediment. Sulfate reduction showed a broad maximum below the sediment surface and a smaller, narrow maximum at the sulfate-methane transition. Methane oxidation was low (0.002-0.1 nmol CH 4 cm -3 d -1 ) throughout the sulfate zone and showed a sharp maximum at the sulfate-methane transition, coinciding with the sulfate reduction maximum. Total anaerobic methane oxidation at two stations was 0.83 and 1.16 mmol CH 4 m -2 d -1 , of which 96% was confined to the sulfate-methane transition. All the methane that was calculated to diffuse up into the sulfate-methane transition was oxidized in this zone. The methane oxidation was equivalent to 10% of the electron donor requirement for the total measured sulfate reduction. A third station showed high sulfate concentrations at all depths sampled and the total methane oxidation was only 0.013 mmol m -2 d -1 . From direct measurements of rates, concentration gradients, and diffusion coefficients, simple calculations were made of sulfate and methane fluxes and of methane production rates

New triboluminescence emitters of inorganic lanthanide salts in CH{sub 4} and C{sub 2}H{sub 2} atmosphere

Energy Technology Data Exchange (ETDEWEB)

Tukhbatullin, A.A., E-mail: adiska0501@gmail.ru; Sharipov, G.L.; Bagautdinova, A.R.

2016-05-15

Excited radicals {sup *}CH and {sup *}C{sub 2} have been registered as light-emitting products of the mechanochemical decomposition of hydrocarbon gases (natural gas, CH{sub 4}, and C{sub 2}H{sub 2}) occurring at decomposition of the hydrated cerium and terbium sulfates under atmosphere of these gases, followed by triboluminescence. The inlet of hydrocarbons almost does not affect the intensity of the solid-state components of triboluminescence, viz., the luminescence of the excited ions Ln{sup 3+}. However, these gases completely suppress the luminescence of molecular nitrogen observed in air (a gas component of triboluminescence). The mechanism of decomposition of methane and acetylene by electrical discharges generated by the destruction of the crystals (the main source of gas component triboluminescence) have been discussed.

BOREAS TGB-1 CH4 Concentration and Flux Data from NSA Tower Sites

Science.gov (United States)

Hall, Forrest G. (Editor); Conrad, Sara K. (Editor); Crill, Patrick; Varner, Ruth K.

2000-01-01

The BOREAS TGB-1 team made numerous measurements of trace gas concentrations and fluxes at various NSA sites. This data set contains half-hourly averages of ambient methane (CH4) measurements and calculated fluxes for the NSA-Fen in 1996 and the NSA-BP and NSA-OJP tower sites in 1994. The purpose of this study was to determine the CH4 flux from the study area by measuring ambient CH 4 concentrations. This flux can then be compared to the chamber flux measurements taken at the same sites. The data are provided in tabular ASCII files.

Microalgae to biofuels: life cycle impacts of methane production of anaerobically digested lipid extracted algae.

Science.gov (United States)

Quinn, Jason C; Hanif, Asma; Sharvelle, Sybil; Bradley, Thomas H

2014-11-01

This study presents experimental measurements of the biochemical methane production for whole and lipid extracted Nannochloropsis salina. Results show whole microalgae produced 430 cm(3)-CH4 g-volatile solids(-1) (g-VS) (σ=60), 3 times more methane than was produced by the LEA, 140 cm(3)-CH4 g-VS(-1) (σ=30). Results illustrate current anaerobic modeling efforts in microalgae to biofuel assessments are not reflecting the impact of lipid removal. On a systems level, the overestimation of methane production is shown to positively skew the environmental impact of the microalgae to biofuels process. Discussion focuses on a comparison results to those of previous anaerobic digestion studies and quantifies the corresponding change in greenhouse gas emissions of the microalgae to biofuels process based on results from this study. Copyright © 2014 Elsevier Ltd. All rights reserved.

Mapping urban pipeline leaks: Methane leaks across Boston

International Nuclear Information System (INIS)

Phillips, Nathan G.; Ackley, Robert; Crosson, Eric R.; Down, Adrian; Hutyra, Lucy R.; Brondfield, Max; Karr, Jonathan D.; Zhao Kaiguang; Jackson, Robert B.

2013-01-01

Natural gas is the largest source of anthropogenic emissions of methane (CH 4 ) in the United States. To assess pipeline emissions across a major city, we mapped CH 4 leaks across all 785 road miles in the city of Boston using a cavity-ring-down mobile CH 4 analyzer. We identified 3356 CH 4 leaks with concentrations exceeding up to 15 times the global background level. Separately, we measured δ 13 CH 4 isotopic signatures from a subset of these leaks. The δ 13 CH 4 signatures (mean = −42.8‰ ± 1.3‰ s.e.; n = 32) strongly indicate a fossil fuel source rather than a biogenic source for most of the leaks; natural gas sampled across the city had average δ 13 CH 4 values of −36.8‰ (±0.7‰ s.e., n = 10), whereas CH 4 collected from landfill sites, wetlands, and sewer systems had δ 13 CH 4 signatures ∼20‰ lighter (μ = −57.8‰, ±1.6‰ s.e., n = 8). Repairing leaky natural gas distribution systems will reduce greenhouse gas emissions, increase consumer health and safety, and save money. Highlights: ► We mapped 3356 methane leaks in Boston. ► Methane leaks in Boston carry an isotopic signature of pipeline natural gas. ► Replacing failing gas pipelines will provide safety, environmental, and economic benefits. - We identified 3356 methane leaks in Boston, with isotopic characteristics consistent with pipeline natural gas.

Methane emissions from MBT landfills

Energy Technology Data Exchange (ETDEWEB)

Heyer, K.-U., E-mail: heyer@ifas-hamburg.de; Hupe, K.; Stegmann, R.

2013-09-15

Highlights: • Compilation of methane generation potential of mechanical biological treated (MBT) municipal solid waste. • Impacts and kinetics of landfill gas production of MBT landfills, approach with differentiated half-lives. • Methane oxidation in the waste itself and in soil covers. • Estimation of methane emissions from MBT landfills in Germany. - Abstract: Within the scope of an investigation for the German Federal Environment Agency (“Umweltbundesamt”), the basics for the estimation of the methane emissions from the landfilling of mechanically and biologically treated waste (MBT) were developed. For this purpose, topical research including monitoring results regarding the gas balance at MBT landfills was evaluated. For waste treated to the required German standards, a methane formation potential of approximately 18–24 m{sup 3} CH{sub 4}/t of total dry solids may be expected. Monitoring results from MBT landfills show that a three-phase model with differentiated half-lives describes the degradation kinetics in the best way. This is due to the fact that during the first years of disposal, the anaerobic degradation processes still proceed relatively intensively. In addition in the long term (decades), a residual gas production at a low level is still to be expected. Most of the soils used in recultivation layer systems at German landfills show a relatively high methane oxidation capacity up to 5 l CH{sub 4}/(m{sup 2} h). However, measurements at MBT disposal sites indicate that the majority of the landfill gas (in particular at non-covered areas), leaves the landfill body via preferred gas emission zones (hot spots) without significant methane oxidation. Therefore, rather low methane oxidation factors are recommended for open and temporarily covered MBT landfills. Higher methane oxidation rates can be achieved when the soil/recultivation layer is adequately designed and operated. Based on the elaborated default values, the First Order Decay (FOD

Microbial diversity and dynamics during methane production from municipal solid waste

Energy Technology Data Exchange (ETDEWEB)

Bareither, Christopher A., E-mail: christopher.bareither@colostate.edu [Civil and Environmental Engineering, Colorado State University, Ft. Collins, CO 80532 (United States); Geological Engineering, University of Wisconsin-Madison, Madison, WI 53706 (United States); Wolfe, Georgia L., E-mail: gwolfe@wisc.edu [Bacteriology, University of Wisconsin-Madison, Madison, WI 53706 (United States); McMahon, Katherine D., E-mail: tmcmahon@engr.wisc.edu [Bacteriology, Civil and Environmental Engineering, University of Wisconsin-Madison, Madison, WI 53706 (United States); Benson, Craig H., E-mail: chbenson@wisc.edu [Civil and Environmental Engineering, Geological Engineering, University of Wisconsin-Madison, Madison, WI 53706 (United States)

2013-10-15

Highlights: ► Similar bacterial communities developed following different start-up operation. ► Total methanogens in leachate during the decelerated methane phase reflected overall methane yield. ► Created correlations between methanogens, methane yield, and available substrate. ► Predominant bacteria identified with syntrophic polysaccharide degraders. ► Hydrogenotrophic methanogens were dominant in the methane generation process. - Abstract: The objectives of this study were to characterize development of bacterial and archaeal populations during biodegradation of municipal solid waste (MSW) and to link specific methanogens to methane generation. Experiments were conducted in three 0.61-m-diameter by 0.90-m-tall laboratory reactors to simulate MSW bioreactor landfills. Pyrosequencing of 16S rRNA genes was used to characterize microbial communities in both leachate and solid waste. Microbial assemblages in effluent leachate were similar between reactors during peak methane generation. Specific groups within the Bacteroidetes and Thermatogae phyla were present in all samples and were particularly abundant during peak methane generation. Microbial communities were not similar in leachate and solid fractions assayed at the end of reactor operation; solid waste contained a more abundant bacterial community of cellulose-degrading organisms (e.g., Firmicutes). Specific methanogen populations were assessed using quantitative polymerase chain reaction. Methanomicrobiales, Methanosarcinaceae, and Methanobacteriales were the predominant methanogens in all reactors, with Methanomicrobiales consistently the most abundant. Methanogen growth phases coincided with accelerated methane production, and cumulative methane yield increased with increasing total methanogen abundance. The difference in methanogen populations and corresponding methane yield is attributed to different initial cellulose and hemicellulose contents of the MSW. Higher initial cellulose and

Microbial diversity and dynamics during methane production from municipal solid waste

International Nuclear Information System (INIS)

Bareither, Christopher A.; Wolfe, Georgia L.; McMahon, Katherine D.; Benson, Craig H.

2013-01-01

Highlights: ► Similar bacterial communities developed following different start-up operation. ► Total methanogens in leachate during the decelerated methane phase reflected overall methane yield. ► Created correlations between methanogens, methane yield, and available substrate. ► Predominant bacteria identified with syntrophic polysaccharide degraders. ► Hydrogenotrophic methanogens were dominant in the methane generation process. - Abstract: The objectives of this study were to characterize development of bacterial and archaeal populations during biodegradation of municipal solid waste (MSW) and to link specific methanogens to methane generation. Experiments were conducted in three 0.61-m-diameter by 0.90-m-tall laboratory reactors to simulate MSW bioreactor landfills. Pyrosequencing of 16S rRNA genes was used to characterize microbial communities in both leachate and solid waste. Microbial assemblages in effluent leachate were similar between reactors during peak methane generation. Specific groups within the Bacteroidetes and Thermatogae phyla were present in all samples and were particularly abundant during peak methane generation. Microbial communities were not similar in leachate and solid fractions assayed at the end of reactor operation; solid waste contained a more abundant bacterial community of cellulose-degrading organisms (e.g., Firmicutes). Specific methanogen populations were assessed using quantitative polymerase chain reaction. Methanomicrobiales, Methanosarcinaceae, and Methanobacteriales were the predominant methanogens in all reactors, with Methanomicrobiales consistently the most abundant. Methanogen growth phases coincided with accelerated methane production, and cumulative methane yield increased with increasing total methanogen abundance. The difference in methanogen populations and corresponding methane yield is attributed to different initial cellulose and hemicellulose contents of the MSW. Higher initial cellulose and

Global Methane Biogeochemistry

Science.gov (United States)

Reeburgh, W. S.

2003-12-01

Methane (CH4) has been studied as an atmospheric constituent for over 200 years. A 1776 letter from Alessandro Volta to Father Campi described the first experiments on flammable "air" released by shallow sediments in Lake Maggiore (Wolfe, 1996; King, 1992). The first quantitative measurements of CH4, both involving combustion and gravimetric determination of trapped oxidation products, were reported in French by Boussingault and Boussingault, 1864 and Gautier (1901), who reported CH4 concentrations of 10 ppmv and 0.28 ppmv (seashore) and 95 ppmv (Paris), respectively. The first modern measurements of atmospheric CH4 were the infrared absorption measurements of Migeotte (1948), who estimated an atmospheric concentration of 2.0 ppmv. Development of gas chromatography and the flame ionization detector in the 1950s led to observations of vertical CH4 distributions in the troposphere and stratosphere, and to establishment of time-series sampling programs in the late 1970s. Results from these sampling programs led to suggestions that the concentration of CH4, as that of CO2, was increasing in the atmosphere. The possible role of CH4 as a greenhouse gas stimulated further research on CH4 sources and sinks. Methane has also been of interest to microbiologists, but findings from microbiology have entered the larger context of the global CH4 budget only recently.Methane is the most abundant hydrocarbon in the atmosphere. It plays important roles in atmospheric chemistry and the radiative balance of the Earth. Stratospheric oxidation of CH4 provides a means of introducing water vapor above the tropopause. Methane reacts with atomic chlorine in the stratosphere, forming HCl, a reservoir species for chlorine. Some 90% of the CH4 entering the atmosphere is oxidized through reactions initiated by the OH radical. These reactions are discussed in more detail by Wofsy (1976) and Cicerone and Oremland (1988), and are important in controlling the oxidation state of the atmosphere

A review of the radiolysis of methane

International Nuclear Information System (INIS)

Norfolk, D.J.

1975-08-01

The review had three objectives: to determine the yields of the primary products and to describe the sequence of reactions in which they take part; to ascertain the effect on these reactions of changes in the physical state of the methane and the quantum energy of the radiation, and of the presence of chemically inert sensitisers; and to identify the situation most similar to the adsorbed phase radiolysis of methane on alumina, and so to predict the likely radiolytic reactions in this system. The main primary product yields in methane gas under γ-irradiation are estimated to be G(CH 4 +) approximately 1.75, G(CH 3 +) approximately 1.46, G(CH 3 ) approximately 1.4 and G(CH 2 ) approximately 1.0. The situation most similar to adsorbed phase radiolysis is inert gas sensitised photolysis at energies below 12.6eV. In this system the major primary process is homolytic dissociation of methane to CH 3 +H. (author)

The Effect of Different Organic Manures Treatments on Methane Emission from Single-cropping Paddy Fields%不同种类有机肥施用对一季稻田CH4排放的影响

Institute of Scientific and Technical Information of China (English)

吴家梅; 纪雄辉; 彭华; 霍莲杰; 刘勇; 朱坚

2011-01-01

Methane emission fluxes from single-cropping paddy fields with application different fertilization treatments were studied by using the static chamber-gas chromatograph techniques with manual method. Results showed that the treatments with application fertilizer increased methane emission compared with no fertilizer treatments (NF). Seasonal average methane emission flux of the incorporation of rice straw and mineral fertilizer( RS) was 31.04 mg·m-2·h-1 which increased by 326.4%( P<0.05) and 211.7% compared with that of the mineral fertilized MF) and incorporation of pig manure and mineral fertilizer( PM), respectively. Seasonal average methane emission flux from the incorporation of chicken manure and the mineral fertilizer( CM) increased by 140.4%( P<0.05) and 75.7%(P<0.05) as compared with MF and PM, respectively. The results indicated there was the obvious influence for RS and CM to methane emission. However, there was no significant difference between NF and PM. According to the analysis of related environmental factors, there was significant correlation between methane emission fluxes and the soil temperature at S cm depth, and the same as the soil Eh. No significant correlation was found between CH4 flux and water depth. The unit yield of Global warming Potential (GWP) in PM treatment was 0.83 kg·kg-1 which suggested PM was a better recommend fertilization during the rice growth. The application of PM took the slight advantages not only in reducing the GWP but also in improving the grain yield.%选取不同施肥处理的一季中稻田为研究对象,采用静态箱-气相色谱法对一季稻CH4排放通量进行手动观测.结果表明,与不施肥相比,各施肥处理CH4平均排放通量均有不同程度增加.其中稻草还田+化肥处理(稻草处理)CH4平均排放通量为31.04mg· m-2· h-1,比化肥处理和猪粪+化肥处理(猪粪处理)分别增加326.4％( P＜0.05)和211.7％(P＜0.05),�

Laboratory-scale measurements of N2O and CH4 emissions from hybrid poplars (Populus deltoides x Populus nigra).

Science.gov (United States)

McBain, M C; Warland, J S; McBride, R A; Wagner-Riddle, C

2004-12-01

The purpose of this study was to determine whether or not young hybrid poplar (Populus deltoides x Populus nigra) could transport landfill biogas internally from the root zone to the atmosphere, thereby acting as conduits for landfill gas release. Fluxes of methane (CH4) and nitrous oxide (N2O) from the seedlings to the atmosphere were measured under controlled conditions using dynamic flux chambers and a tunable diode laser trace gas analyser (TDLTGA). Nitrous oxide was emitted from the seedlings, but only when extremely high soil N2O concentrations were applied to the root zone. In contrast, no detectable emissions of CH4 were measured in a similar experimental trial. Visible plant morphological responses, characteristic of flood-tolerant trees attempting to cope with the negative effects of soil hypoxia, were observed during the CH4 experiments. Leaf chlorosis, leaf abscission and adventitious roots were all visible plant responses. In addition, seedling survival was observed to be highest in the biogas 'hot spot' areas of a local municipal solid waste landfill involved in this study. Based on the available literature, these observations suggest that CH4 can be transported internally by Populus deltoides x Populus nigra seedlings in trace amounts, although future research is required to fully test this hypothesis.

Induction of enhanced methane oxidation in compost: Temperature and moisture response

International Nuclear Information System (INIS)

Mor, Suman; Visscher, Alex de; Ravindra, Khaiwal; Dahiya, R.P.; Chandra, A.; Cleemput, Oswald van

2006-01-01

Landfilling is one of the most common ways of municipal solid waste disposal. Degradation of organic waste produces CH 4 and other landfill gases that significantly contribute to global warming. However, before entering the atmosphere, part of the produced CH 4 can be oxidised while passing through the landfill cover. In the present study, the oxidation rate of CH 4 was studied with various types of compost as possible landfill cover. The influence of incubation time, moisture content and temperature on the CH 4 oxidation capacity of different types of compost was examined. It was observed that the influence of moisture content and temperature on methane oxidation is time-dependent. Maximum oxidation rates were observed at moisture contents ranging from 45% to 110% (dry weight basis), while the optimum temperature ranged from 15 to 30 deg. C

Evidence for methane in orion KL: A search for the 4.6 Gigahertz line

International Nuclear Information System (INIS)

Wilson, T.L.; Snyder, L.E.

1985-01-01

A sensitive search for the J = 11 E(2)-E(1) transition of interstellar methane (CH 4 ) has resulted in a peak upper limit which is much less than the value reported by Fox and Jennings in 1978. When combined with the negative results reported by Ellder et al. in 1980, these data rule out the detection of CH 4 in Orion KL previously claimed by Fox and Jennings

Evidence for methane in Orion KL - a search for the 4.6 gigahertz line

International Nuclear Information System (INIS)

Wilson, T.L.; Snyder, L.E.

1985-01-01

A sensitive search for J = 11 E(2)-E(1) transition of interstellar methane (CH4) has resulted in a peak upper limit which is much less than the value reported by Fox and Jennings (1978). When combined with the negative results reported by Ellder et al. (1980), these data rule out the detection of CH4 in Orion KL previously claimed by Fox and Jennings. 7 references

CO2 adsorption-assisted CH4 desorption on carbon models of coal surface: A DFT study

Science.gov (United States)

Xu, He; Chu, Wei; Huang, Xia; Sun, Wenjing; Jiang, Chengfa; Liu, Zhongqing

2016-07-01

Injection of CO2 into coal is known to improve the yields of coal-bed methane gas. However, the technology of CO2 injection-enhanced coal-bed methane (CO2-ECBM) recovery is still in its infancy with an unclear mechanism. Density functional theory (DFT) calculations were performed to elucidate the mechanism of CO2 adsorption-assisted CH4 desorption (AAD). To simulate coal surfaces, different six-ring aromatic clusters (2 × 2, 3 × 3, 4 × 4, 5 × 5, 6 × 6, and 7 × 7) were used as simplified graphene (Gr) carbon models. The adsorption and desorption of CH4 and/or CO2 on these carbon models were assessed. The results showed that a six-ring aromatic cluster model (4 × 4) can simulate the coal surface with limited approximation. The adsorption of CO2 onto these carbon models was more stable than that in the case of CH4. Further, the adsorption energies of single CH4 and CO2 in the more stable site were -15.58 and -18.16 kJ/mol, respectively. When two molecules (CO2 and CH4) interact with the surface, CO2 compels CH4 to adsorb onto the less stable site, with a resulting significant decrease in the adsorption energy of CH4 onto the surface of the carbon model with pre-adsorbed CO2. The Mulliken charges and electrostatic potentials of CH4 and CO2 adsorbed onto the surface of the carbon model were compared to determine their respective adsorption activities and changes. At the molecular level, our results showed that the adsorption of the injected CO2 promoted the desorption of CH4, the underlying mechanism of CO2-ECBM.

Terrestrial plant methane production and emission

DEFF Research Database (Denmark)

Bruhn, Dan; Møller, Ian M.; Mikkelsen, Teis Nørgaard

2012-01-01

In this minireview, we evaluate all experimental work published on the phenomenon of aerobic methane (CH4) generation in terrestrial plants and plant. Clearly, despite much uncertainty and skepticism, we conclude that the phenomenon is true. Four stimulating factors have been observed to induce...... aerobic CH4 into a global budget is inadequate. Thus it is too early to draw the line under the aerobic methane emission in plants. Future work is needed for establishing the relative contribution of several proven potential CH4 precursors in plant material....

Mesophilic anaerobic co-digestion of municipal solid waste and sewage sludge

DEFF Research Database (Denmark)

Aghdam, Ehsan Fathi; Kinnunen, V.; Rintala, Jukka A.

2015-01-01

This paper presents mesophilic anaerobic digestion (AD) of organic fraction of municipal solid waste (OFMSW), biowaste (BW), sewage sludge (SS), and co-digestion of BW and SS. Average methane yields of 386 ± 54, 385 ± 82, 198 ± 14, and 318 ± 59 L CH4/kg volatile solids (VS) were obtained for OFMSW...

BOREAS TGB-1 Soil CH4 and CO2 Profile Data from NSA Tower Sites

Science.gov (United States)

Crill, Patrick; Varner, Ruth K.; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor)

2000-01-01

The BOREAS TGB-1 team made numerous measurements of trace gas concentrations and fluxes at various NSA sites. This data set contains methane (CH4) and carbon dioxide (CO2) concentrations in soil profiles from the NSA-OJP, NSA-OBS, NSA-YJP, and NSA-BP sites during the period of 23-May to 20-Sep-1994. The soil gas sampling profiles of CH 4 and CO 2 were completed to quantify controls on CO2 and CH4 fluxes in the boreal forest. The data are provided in tabular ASCII files.

Bimolecular reaction of CH3 + CO in solid p-H2: Infrared absorption of acetyl radical (CH3CO) and CH3-CO complex

Science.gov (United States)

Das, Prasanta; Lee, Yuan-Pern

2014-06-01

We have recorded infrared spectra of acetyl radical (CH3CO) and CH3-CO complex in solid para-hydrogen (p-H2). Upon irradiation at 248 nm of CH3C(O)Cl/p-H2 matrices, CH3CO was identified as the major product; characteristic intense IR absorption features at 2990.3 (ν9), 2989.1 (ν1), 2915.6 (ν2), 1880.5 (ν3), 1419.9 (ν10), 1323.2 (ν5), 836.6 (ν7), and 468.1 (ν8) cm-1 were observed. When CD3C(O)Cl was used, lines of CD3CO at 2246.2 (ν9), 2244.0 (ν1), 1866.1 (ν3), 1046.7 (ν5), 1029.7 (ν4), 1027.5 (ν10), 889.1 (ν6), and 723.8 (ν7) cm-1 appeared. Previous studies characterized only three vibrational modes of CH3CO and one mode of CD3CO in solid Ar. In contrast, upon photolysis of a CH3I/CO/p-H2 matrix with light at 248 nm and subsequent annealing at 5.1 K before re-cooling to 3.2 K, the CH3-CO complex was observed with characteristic IR features at 3165.7, 3164.5, 2150.1, 1397.6, 1396.4, and 613.0 cm-1. The assignments are based on photolytic behavior, observed deuterium isotopic shifts, and a comparison of observed vibrational wavenumbers and relative IR intensities with those predicted with quantum-chemical calculations. This work clearly indicates that CH3CO can be readily produced from photolysis of CH3C(O)Cl because of the diminished cage effect in solid p-H2 but not from the reaction of CH3 + CO because of the reaction barrier. Even though CH3 has nascent kinetic energy greater than 87 kJ mol-1 and internal energy ˜42 kJ mol-1 upon photodissociation of CH3I at 248 nm, its energy was rapidly quenched so that it was unable to overcome the barrier height of ˜27 kJ mol-1 for the formation of CH3CO from the CH3 + CO reaction; a barrierless channel for formation of a CH3-CO complex was observed instead. This rapid quenching poses a limitation in production of free radicals via bimolecular reactions in p-H2.

Ion irradiation of CH4-containing icy mixtures

International Nuclear Information System (INIS)

Baratta, G.A.; Domingo, M.; Ferini, G.; Leto, G.; Palumbo, M.E.; Satorre, M.A.; Strazzulla, G.

2003-01-01

We have studied by infrared absorption spectroscopy the effects of ion irradiation with 60 keV Ar 2+ ions on pure methane (CH 4 ) ice at 12 K and mixtures with water (H 2 O) and nitrogen (N 2 ). Ion irradiation, among other effects, causes the rupture of original molecular bonds and the formation of molecular species not present in the initial ice. Here we present the experimental results and discuss their astrophysical relevance

Experimental Equipment Validation for Methane (CH4) and Carbon Dioxide (CO2) Hydrates

Science.gov (United States)

Saad Khan, Muhammad; Yaqub, Sana; Manner, Naathiya; Ani Karthwathi, Nur; Qasim, Ali; Mellon, Nurhayati Binti; Lal, Bhajan

2018-04-01

Clathrate hydrates are eminent structures regard as a threat to the gas and oil industry in light of their irritating propensity to subsea pipelines. For natural gas transmission and processing, the formation of gas hydrate is one of the main flow assurance delinquent has led researchers toward conducting fresh and meticulous studies on various aspects of gas hydrates. This paper highlighted the thermodynamic analysis on pure CH4 and CO2 gas hydrates on the custom fabricated equipment (Sapphire cell hydrate reactor) for experimental validation. CO2 gas hydrate formed at lower pressure (41 bar) as compared to CH4 gas hydrate (70 bar) while comparison of thermodynamic properties between CH4 and CO2 also presented in this study. This preliminary study could provide pathways for the quest of potent hydrate inhibitors.

Methane oxidation in pig and cattle slurry storages, and effects of surface crust moisture and methane availability

DEFF Research Database (Denmark)

Petersen, S.O.; Ambus, P.

2006-01-01

Storages with liquid manure (slurry) may develop a surface crust of particulate organic matter, or an artificial crust can be established. Slurry storages are net sources of atmospheric methane (CH4), but a potential for bacterial oxidation of CH4 in surface crusts was recently suggested in a study......2 during incubation, while intact subsamples were used to characterize CH4 oxidation as a function of CH4 availability and moisture content. Methane oxidation was observed in all materials except for an expanded clay product (Leca) sampled from a pig slurry storage. Despite significant variation...... crusts indicates that there is a potential for stimulating the process by manipulation of gas phase composition above the stored slurry....

High temperature infrared absorption cross sections of methane near 3.4 μm in Ar and CO2 mixtures

Science.gov (United States)

Koroglu, Batikan; Neupane, Sneha; Pryor, Owen; Peale, Robert E.; Vasu, Subith S.

2018-02-01

The absorption cross-sections of CH4 at two wavelengths in the mid-IR region: λpeak = 3403.4 nm and λvalley = 3403.7 nm were measured. Data were taken using three different compositions of non-reactive gas mixtures comprising CH4/Ar/CO2 between 700 laser. Also, broadband room temperature methane cross section measurements were performed using a Fourier transform infrared spectrometer and the cascade laser to gain a better insight into the changes of the line shapes in various bath gasses (Ar, CO2, and N2). An application of the high-temperature cross-section data was demonstrated to determine the concentration of methane during oxy-methane combustion in a mixture of CO2, O2, and Ar. Current measurements will be valuable addition to the spectroscopy database for methane- an important fuel used for power generation and heating around the world.

Effects of Boreal Lake Wetlands on Atmospheric 13CH3D and 12CH2D2

Science.gov (United States)

Haghnegahdar, M. A.; Kohl, I. E.; Schauble, E. A.; Walter Anthony, K. M.; Young, E. D.

2017-12-01

Recently, we developed a theoretical model to investigate the potential use of 13CH3D and 12CH2D2 as tools for tracking atmospheric methane budget. We used electronic structure methods to estimate kinetic isotope fractionations associated with the major sink reactions of CH4 in air (reactions with •OH and Cl•), and literature data with reconnaissance measurements of the relative abundances of 13CH3D and 12CH2D2 to estimate the compositions of the largest atmospheric sources. Here we present new methane rare isotopologue data from boreal wetlands, comprising one of the most important sources, in order to evaluate the robustness of the model. Boreal wetlands (>55° N) account for more than half of the wetland area in the Northern hemisphere. We analyzed methane samples from high latitude lakes representing different geographical regions, geological and ecological contexts, methane fluxes, and isotopic signatures. Using clumped isotopes of CH4 we are able to determine the likely production mechanism for natural CH4 samples. So far, all of our analyzed samples except one plot in the microbial pure-culture methanogenesis field (Young et al. 2017) with ranges of -0.2‰ to +1.2‰ for Δ13CH3D, and -29.6‰ to -18.2‰ for Δ12CH2D2. These compositions are far from equilibrium. The one exception, from Lake Doughnut, Alaska, exhibits Δ13CH3D and Δ12CH2D2 values of +5.2‰ and +18.7‰, respectively, which fall near ambient thermodynamic equilibrium values. This may be an effect of methanotrophy. Mean Δ13CH3D and Δ12CH2D2 for all lake samples are +1.7‰ and -15.4‰ respectively, compared to our original estimate of +6.1‰ and +21.2‰ for the wetland methane source based on an assumption of equilibrium. If we assume that these samples are representative of the overall wetland source, Δ13CH3D decreases by 0.8‰ and Δ12CH2D2 decreases by 0.6‰ in our model of bulk atmospheric methane. Δ13CH3D and Δ12CH2D2 values of air (including •OH and Cl• sink

Sources of atmospheric methane from coastal marine wetlands

International Nuclear Information System (INIS)

Harriss, R.C.; Sebacher, D.I.; Bartlett, K.B.; Bartlett, D.S.

1982-01-01

Biological methanogenesis in wetlands is believed to be one of the major sources of global tropospheric methane. The present paper reports measurements of methane distribution in the soils, sediments, water and vegetation of coastal marine wetlands. Measurements, carried out in the salt marshes Bay Tree Creek in Virginia and Panacea in northwest Florida, reveal methane concentrations in soils and sediments to vary with depth below the surface and with soil temperature. The fluxes of methane from marsh soils to the atmosphere at the soil-air interface are estimated to range from -0.00067 g CH 4 /sq m per day (methane sink) to 0.024 g CH 4 /sq m per day, with an average value of 0.0066 g CH 4 /sq m per day. Data also demonstrate the important role of tidal waters percolating through marsh soils in removing methane from the soils and releasing it to the atmosphere. The information obtained, together with previous studies, provides a framework for the design of a program based on in situ and remote sensing measurements to study the global methane cycle

Calibration and field testing of cavity ring-down laser spectrometers measuring CH4, CO2, and δ13CH4 deployed on towers in the Marcellus Shale region

Directory of Open Access Journals (Sweden)

N. L. Miles

2018-03-01

Full Text Available Four in situ cavity ring-down spectrometers (G2132-i, Picarro, Inc. measuring methane dry mole fraction (CH4, carbon dioxide dry mole fraction (CO2, and the isotopic ratio of methane (δ13CH4 were deployed at four towers in the Marcellus Shale natural gas extraction region of Pennsylvania. In this paper, we describe laboratory and field calibration of the analyzers for tower-based applications and characterize their performance in the field for the period January–December 2016. Prior to deployment, each analyzer was tested using bottles with various isotopic ratios, from biogenic to thermogenic source values, which were diluted to varying degrees in zero air, and an initial calibration was performed. Furthermore, at each tower location, three field tanks were employed, from ambient to high mole fractions, with various isotopic ratios. Two of these tanks were used to adjust the calibration of the analyzers on a daily basis. We also corrected for the cross-interference from ethane on the isotopic ratio of methane. Using an independent field tank for evaluation, the standard deviation of 4 h means of the isotopic ratio of methane difference from the known value was found to be 0.26 ‰ δ13CH4. Following improvements in the field tank testing scheme, the standard deviation of 4 h means was 0.11 ‰, well within the target compatibility of 0.2 ‰. Round-robin style testing using tanks with near-ambient isotopic ratios indicated mean errors of −0.14 to 0.03 ‰ for each of the analyzers. Flask to in situ comparisons showed mean differences over the year of 0.02 and 0.08 ‰, for the east and south towers, respectively. Regional sources in this region were difficult to differentiate from strong perturbations in the background. During the afternoon hours, the median differences of the isotopic ratio measured at three of the towers, compared to the background tower, were &minus0.15 to 0.12 ‰ with standard deviations of the 10�

Calibration and field testing of cavity ring-down laser spectrometers measuring CH4, CO2, and δ13CH4 deployed on towers in the Marcellus Shale region

Science.gov (United States)

Miles, Natasha L.; Martins, Douglas K.; Richardson, Scott J.; Rella, Christopher W.; Arata, Caleb; Lauvaux, Thomas; Davis, Kenneth J.; Barkley, Zachary R.; McKain, Kathryn; Sweeney, Colm

2018-03-01

Four in situ cavity ring-down spectrometers (G2132-i, Picarro, Inc.) measuring methane dry mole fraction (CH4), carbon dioxide dry mole fraction (CO2), and the isotopic ratio of methane (δ13CH4) were deployed at four towers in the Marcellus Shale natural gas extraction region of Pennsylvania. In this paper, we describe laboratory and field calibration of the analyzers for tower-based applications and characterize their performance in the field for the period January-December 2016. Prior to deployment, each analyzer was tested using bottles with various isotopic ratios, from biogenic to thermogenic source values, which were diluted to varying degrees in zero air, and an initial calibration was performed. Furthermore, at each tower location, three field tanks were employed, from ambient to high mole fractions, with various isotopic ratios. Two of these tanks were used to adjust the calibration of the analyzers on a daily basis. We also corrected for the cross-interference from ethane on the isotopic ratio of methane. Using an independent field tank for evaluation, the standard deviation of 4 h means of the isotopic ratio of methane difference from the known value was found to be 0.26 ‰ δ13CH4. Following improvements in the field tank testing scheme, the standard deviation of 4 h means was 0.11 ‰, well within the target compatibility of 0.2 ‰. Round-robin style testing using tanks with near-ambient isotopic ratios indicated mean errors of -0.14 to 0.03 ‰ for each of the analyzers. Flask to in situ comparisons showed mean differences over the year of 0.02 and 0.08 ‰, for the east and south towers, respectively. Regional sources in this region were difficult to differentiate from strong perturbations in the background. During the afternoon hours, the median differences of the isotopic ratio measured at three of the towers, compared to the background tower, were &minus0.15 to 0.12 ‰ with standard deviations of the 10 min isotopic ratio differences of 0.8 �

Methane oxidation associated to submerged brown-mosses buffers methane emissions from Siberian polygonal peatlands

Science.gov (United States)

Liebner, Susanne; Zeyer, Josef; Knoblauch, Christian

2010-05-01

Circumpolar peatlands store roughly 18 % of the globally stored carbon in soils [based on 1, 2]. Also, northern wetlands and tundra are a net source of methane (CH4), an effective greenhouse gas (GHG), with an estimated annual CH4 release of 7.2% [3] or 8.1% [4] of the global total CH4 emission. Although it is definite that Arctic tundra significantly contributes to the global methane emissions in general, regional variations in GHG fluxes are enormous. CH4 fluxes of polygonal tundra within the Siberian Lena Delta, for example, were reported to be low [5, 6], particularly at open water polygonal ponds and small lakes [7] which make up around 10 % of the delta's surface. Low methane emissions from polygonal ponds oppose that Arctic permafrost thaw ponds are generally known to emit large amounts of CH4 [8]. Combining tools of biogeochemistry and molecular microbiology, we identified sinks of CH4 in polygonal ponds from the Lena Delta that were not considered so far in GHG studies from Arctic wetlands. Pore water CH4 profiling in polygonal ponds on Samoylov, a small island in the central part of the Lena Delta, revealed a pronounced zone of CH4 oxidation near the vegetation surface in submerged layers of brown-mosses. Here, potential CH4 oxidation was an order of magnitude higher than in non-submerged mosses and in adjacent bulk soil. We could additionally show that this moss associated methane oxidation (MAMO) is hampered when exposure of light is prevented. Shading of plots with submerged Scorpidium scorpioides inhibited MAMO leading to higher CH4 concentrations and an increase in CH4 fluxes by a factor of ~13. Compared to non-submerged mosses, the submerged mosses also showed significantly lower δ13C values indicating that they use carbon dioxide derived from methane oxidation for photosynthesis. Applying stable isotope probing of DNA, type II methanotrophs were identified to be responsible for the oxidation of CH4 in the submerged Scorpidium scorpioides. Our

The H2/CH4 ratio during serpentinization cannot reliably identify biological signatures

OpenAIRE

Huang, Ruifang; Sun, Weidong; Liu, Jinzhong; Ding, Xing; Peng, Shaobang; Zhan, Wenhuan

2016-01-01

Serpentinization potentially contributes to the origin and evolution of life during early history of the Earth. Serpentinization produces molecular hydrogen (H2) that can be utilized by microorganisms to gain metabolic energy. Methane can be formed through reactions between molecular hydrogen and oxidized carbon (e.g., carbon dioxide) or through biotic processes. A simple criterion, the H2/CH4 ratio, has been proposed to differentiate abiotic from biotic methane, with values approximately lar...

Breeding Ruminants that Emit Less Methane – The Role of International Collaboration

NARCIS (Netherlands)

Oddy, V.H.; Haas, de Y.; Basarab, J.; Cammack, K.; Hayes, B.J.; Hegarty, R.; Lassen, J.; McEwan, J.; Miller, S.; Pinares-Patino, C.

2014-01-01

Ruminants contribute to global greenhouse gas (GHG) emissions, principally as enteric methane (CH4) emissions. Direct selection for reduced CH4 emissions through combined selection for both low residual feed intake and methane yield could potentially provide a long term reduction in enteric methane

Early Mars serpentinization-derived CH4 reservoirs, H2 induced warming and paleopressure evolution

Science.gov (United States)

Lasue, J.; Chassefiere, E.; Langlais, B.; Quesnel, Y.

2016-12-01

CH4 has been observed on Mars both by remote sensing and in situ during the past 15 years. Early Mars serpentinization is one possible abiotic mechanism that could not only produce methane, but also explain the observed Martian remanent magnetic field. Assuming a cold early Mars, a cryosphere could trap such CH4 as clathrates in stable form at depth. We recently estimated the maximum storage capacity of such clathrate layer to be about 2x1019 to 2x1020 moles of methane. Such reservoirs may be stable or unstable, depending on many factors that are poorly constrained: major and sudden geological events such as the Tharsis bulge formation, the Hellas impact or the martian polar wander, could have destabilized the clathrates early in the history of the planet and released large quantities of gas in the atmosphere. Here we estimate the associated amounts of serpentinization-derived CH4 stored in the cryosphere that have been released to the atmosphere at the end of the Noachian and the beginning of the Hesperian. Due to rapid clathrate dissociation and photochemical conversion of CH4 to H2, these episodes of massive CH4 release may have resulted in transient H2-rich atmospheres, at typical levels of 10-20% in a background 1-2 bar CO2 atmosphere. We propose that the early Mars cryosphere had a sufficient CH4 storage capacity to have maintained H2-rich transient atmospheres during a total time period up to several Myr or tens of Myr, having potentially contributed - by collision-induced heating effect of atmospheric H2 - to the formation of valley networks during the late Noachian and early Hesperian.

An investigation of phase transitions in solid methane and deuterated derivatives to pressures of 3 kbar

International Nuclear Information System (INIS)

Sprik, M.

1982-01-01

The first part of this thesis is an experimental investigation of the interaction responsible for the I-II transition and the second part comprises three theoretical studies of several of the properties of phase I and II. The first chapter of part I, is a general introduction to a thermodynamic treatment of the isotope effect in an orientational phase transition. The thermodynamic approach yields a corresponding state model for the phase diagrams of the five isotopes of methane (CH 4 , CHD 3 , CH 2 D 2 , CH 3 D and CD 4 ). In the remaining two chapters of part I, the corresponding state relation mentioned above is applied to the I-II transition of methane in order to obtain an experimental value for the effective exponent n of the dependence on intermolecular separation of the ordering anisotropic interaction. Part II starts with a derivation of a quasi-classical approximation to the statistical density matrix of a free spherical top. While the orientational system is treated classically, the consequences of the other characteristic of the methane molecules are considered, i.e. the high approximately odd symmetry of the molecule (the octupole field in phase II is odd under spatial inversion). It is argued that the renormalization group analysis of critical phenomena in certain highly complicated antiferromagnetic systems may be equally well applied to the I-II transition in methane. Finally, the study of the quantum effect in phase II is resumed. The spin lattice relaxation time at very low temperature is calculated from first principles using an orientational dynamical process of purely quantum-mechanical nature. (Auth.)

[Agroindustrial wastes methanization and bacterial composition in anaerobic digestion].

Science.gov (United States)

González-Sánchez, María E; Pérez-Fabiel, Sergio; Wong-Villarreal, Arnoldo; Bello-Mendoza, Ricardo; Yañez-Ocampo, Gustavo

2015-01-01

The tons of organic waste that are annually generated by agro-industry, can be used as raw material for methane production. For this reason, it is important to previously perform biodegradability tests to organic wastes for their full scale methanization. This paper addresses biodegradability, methane production and the behavior of populations of eubacteria and archaeabacteria during anaerobic digestion of banana, mango and papaya agroindustrial wastes. Mango and banana wastes had higher organic matter content than papaya in terms of their volatile solids and total solid rate (94 and 75% respectively). After 63 days of treatment, the highest methane production was observed in banana waste anaerobic digestion: 63.89ml CH4/per gram of chemical oxygen demand of the waste. In the PCR-DGGE molecular analysis, different genomic footprints with oligonucleotides for eubacteria and archeobacteria were found. Biochemical methane potential results proved that banana wastes have the best potential to be used as raw material for methane production. The result of a PCR- DGGE analysis using specific oligonucleotides enabled to identify the behavior of populations of eubacteria and archaeabacteria present during the anaerobic digestion of agroindustrial wastes throughout the process. Copyright © 2015 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

Combined H2/CH4 cold moderator for a short pulse neutron source

International Nuclear Information System (INIS)

Williamson, K.D.; Lucas, A.T.

1988-01-01

Very low temperature methane would be an ideal moderating material as it has a high hydrogen density and many low frequency modes which facilitate thermalization. Such moderators are in service at two major world facilities, KEK (Japan) and Argonne National Laboratory (USA). Unfortunately solid methane has very low thermal conductivity and is subject to radiation damage making a moderator of this type impractical for use in high intensity beam. This report outlines a possible alternative using small spheres of solid methane in a matrix of supercritical hydrogen at 25 K. 4 figs

Modelling of SOEC-FT reactor: Pressure effects on methanation process

International Nuclear Information System (INIS)

Chen, Bin; Xu, Haoran; Ni, Meng

2017-01-01

Highlights: • Numerical study on combined SOEC-FT reactor in pressurized condition. • Effects of operating pressure on co-electrolysis and CH_4 production are studied. • The lower limit temperature of the FT section is dependent on the operating pressure. • The CH_4 production can be improved at higher voltage due to the current increase. • Effects of higher exchange current density is predicted at different temperature. - Abstract: In this paper a numerical model is developed for a novel reactor combining a Solid Oxide Electrolyzer Cell (SOEC) section with a Fischer Tropsch like section for methane production under pressurized & temperature-gradient condition. Governing equations for mass, momentum, charge transport are solved with Finite Element Method. The chemical reaction kinetics of reversible water gas shift reaction and reversible methanation reaction in Ni/YSZ cathode are fully considered. The model is validated by comparing simulation results with experimental data. Parametric simulations are conducted to understand the physical-chemical processes in the reactor with a focus on the pressure effect. It is predicted that the optimal operating pressure is around 3 bar, beyond which the CH_4 conversion ratio (2.5 times enhanced than 1 bar operating) cannot be further increased. It is also found that it is feasible to operate the pressurized SOEC at a lower temperature for CH_4 production with improved catalyst activity.

Coupling a Neural Network with Atmospheric Flow Simulations to Locate and Quantify CH4 Emissions at Well Pads

Science.gov (United States)

Travis, B. J.; Sauer, J.; Dubey, M. K.

2017-12-01

Methane (CH4) leaks from oil and gas production fields are a potentially significant source of atmospheric methane. US DOE's ARPA-E office is supporting research to locate methane emissions at 10 m size well pads to within 1 m. A team led by Aeris Technologies, and that includes LANL, Planetary Science Institute and Rice University has developed an autonomous leak detection system (LDS) employing a compact laser absorption methane sensor, a sonic anemometer and multiport sampling. The LDS system analyzes monitoring data using a convolutional neural network (cNN) to locate and quantify CH4 emissions. The cNN was trained using three sources: (1) ultra-high-resolution simulations of methane transport provided by LANL's coupled atmospheric transport model HIGRAD, for numerous controlled methane release scenarios and methane sampling configurations under variable atmospheric conditions, (2) Field tests at the METEC site in Ft. Collins, CO., and (3) Field data from other sites where point-source surface methane releases were monitored downwind. A cNN learning algorithm is well suited to problems in which the training and observed data are noisy, or correspond to complex sensor data as is typical of meteorological and sensor data over a well pad. Recent studies with our cNN emphasize the importance of tracking wind speeds and directions at fine resolution ( 1 second), and accounting for variations in background CH4 levels. A few cases illustrate the importance of sufficiently long monitoring; short monitoring may not provide enough information to determine accurately a leak location or strength, mainly because of short-term unfavorable wind directions and choice of sampling configuration. Length of multiport duty cycle sampling and sample line flush time as well as number and placement of monitoring sensors can significantly impact ability to locate and quantify leaks. Source location error at less than 10% requires about 30 or more training cases.

Conversion of hydrocarbons in solid oxide fuel cells

DEFF Research Database (Denmark)

Mogensen, Mogens Bjerg; Kammer Hansen, K.

2003-01-01

Recently, a number of papers about direct oxidation of methane and hydrocarbon in solid oxide fuel cells (SOFC) at relatively low temperatures (about 700degreesC) have been published. Even though the conversion of almost dry CH4 at 1000degreesC on ceramic anodes was demonstrated more than 10 years...

Corona discharge experiments in admixtures of N2 and CH4: a laboratory simulation of Titan's atmosphere

International Nuclear Information System (INIS)

Horvath, G; Skalny, J D; Klas, M; Zahoran, M; Mason, N J; Vladoiu, R; Manole, M

2009-01-01

A positive corona discharge fed by a N 2 : CH 4 mixture (98 : 2) at atmospheric pressure and ambient temperature has been studied as a laboratory mimic of the chemical processes occurring in the atmosphere of Titan, Saturn's largest moon. In situ measurements of UV and IR transmission spectra within the discharge have shown that the main chemical product is C 2 H 2 , produced by dissociation of CH 4 , with small but significant traces of ethane and HCN, all species that have been detected in Titan's atmosphere. A small amount (0.2%) of CH 4 was decomposed after 12 min of treatment requiring an average energy of 2.7 kWh g -1 . After 14 min the discharge was terminated due to the formation of a solid yellow deposit on the central wire electrode. Such a deposit is similar to that observed in other discharges and is believed to be an analogue of the aerosol and dust observed in Titan's atmosphere and is composed of chemical species commonly known as 'tholins'. We have also explored the electrical properties of the discharge. The admixture of methane into nitrogen caused an increase in the onset voltage of the discharge and consequently led to a reduction in the measured discharge current.

The global variation of CH4 and CO as seen by SCIAMACHY

NARCIS (Netherlands)

Straume, A.G.; Schrijver, H.; Gloudemans, A.M.S.; Houweling, S.; Aben, I.; Maurellis, A.N.; de Laat, A.T.J.; Kleipool, Q.; Lichtenberg, G.; van Hees, R.; Meirink, J.F.; Krol, M.

2005-01-01

The methane (CH4) and carbon monoxide (CO) total columns retrieved from SCIAMACHY's near-infrared channel 8 have been compared to satellite measurements by the MOPITT instrument and chemistry transport model calculations (TM3). Results from the SRON retrieval algorithm IMLM (v5.1) are presented here

Methane-induced Activation Mechanism of Fused Ferric Oxide-Alumina Catalysts during Methane Decomposition

KAUST Repository

Reddy Enakonda, Linga

2016-06-27

Activation of Fe2O3-Al2O3 with CH4 (instead of H2) is a meaningful method to achieve catalytic methane decomposition (CMD). This reaction of CMD is more economic and simple against commercial methane steam reforming (MSR) as it produces COx-free H2. In this study, for the first time, structure changes of the catalyst were screened during CH4 reduction with time on stream. The aim was to optimize the pretreatment conditions through understanding the activation mechanism. Based on results from various characterization techniques, reduction of Fe2O3 by CH4 proceeds in three steps: Fe2O3→Fe3O4→FeO→Fe0. Once Fe0 is formed, it decomposes CH4 with formation of Fe3C, which is the crucial initiation step in the CMD process to initiate formation of multiwall carbon nanotubes. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Bio-methanation of municipal solid wastes for ecological balance and sustainable development

International Nuclear Information System (INIS)

Sadangi, Subhash Ch.

2000-01-01

The importance of bio-methanation of municipal solid wastes for over all improvement of environment and for converting wastes into wealth, the national planners should make all out efforts to implement the concept on a large scale to meet the challenges of future demands of energy, ecology and sustainable development. The huge quantity of methane generated from MSW (Municipal Solid Wastes) after treatment and desulfuration is utilised to generate electric power. Hence, development of methane resource as an alternative to energy source has attracted attention in recent years in many parts of the world. Methane is a much more powerful green house gas as its adverse impacts are felt more intensely due to its higher residence and higher potency in the atmosphere. The article highlights the process of bio-methanation of municipal solid wastes and planning for ecological balance and sustainable development

CO2 Reforming of CH4 by Atmospheric Pressure Abnormal Glow Plasma

International Nuclear Information System (INIS)

Chen Qi; Dai Wei; Tao Xumei; Yu Hui; Dai Xiaoyan; Yin Yongxiang

2006-01-01

A novel plasma atmospheric pressure abnormal glow discharge was used to investigate synthesis gas production from reforming methane and carbon dioxide. Special attentions were paid to the discharge characteristics and CH 4 , CO 2 conversion, H 2 , CO selectivity, and ratio of H 2 /CO varied with the changing of discharging power, the total flux, and the ratio of CH 4 /CO 2 . Experiments were performed in wider operation variables, the discharging power of 240 to 600 W, the CH 4 /CO 2 of 0.2 to 1.0 and the total flux of 140 to 500 mL/min. The experiments showed that the conversion of CH 4 and CO 2 was up to 91.9% and 83.2%, the selectivity of CO and H 2 was also up to 80% and 90% and H 2 /CO mole ratio was 0.2 to 1.2, respectively. A brief analysis for discharge characteristics and the experimental results were given

Centennial evolution of the atmospheric methane budget: what do the carbon isotopes tell us?

Directory of Open Access Journals (Sweden)

K. R. Lassey

2007-01-01

Full Text Available Little is known about how the methane source inventory and sinks have evolved over recent centuries. New and detailed records of methane mixing ratio and isotopic composition (12CH4, 13CH4 and 14CH4 from analyses of air trapped in polar ice and firn can enhance this knowledge. We use existing bottom-up constructions of the source history, including "EDGAR"-based constructions, as inputs to a model of the evolving global budget for methane and for its carbon isotope composition through the 20th century. By matching such budgets to atmospheric data, we examine the constraints imposed by isotope information on those budget evolutions. Reconciling both 12CH4 and 13CH4 budgets with EDGAR-based source histories requires a combination of: a greater proportion of emissions from biomass burning and/or of fossil methane than EDGAR constructions suggest; a greater contribution from natural such emissions than is commonly supposed; and/or a significant role for active chlorine or other highly-fractionating tropospheric sink as has been independently proposed. Examining a companion budget evolution for 14CH4 exposes uncertainties in inferring the fossil-methane source from atmospheric 14CH4 data. Specifically, methane evolution during the nuclear era is sensitive to the cycling dynamics of "bomb 14C" (originating from atmospheric weapons tests through the biosphere. In addition, since ca. 1970, direct production and release of 14CH4 from nuclear-power facilities is influential but poorly quantified. Atmospheric 14CH4 determinations in the nuclear era have the potential to better characterize both biospheric carbon cycling, from photosynthesis to methane synthesis, and the nuclear-power source.

Quantification of methane emissions from danish landfills

DEFF Research Database (Denmark)

Scheutz, Charlotte; Mønster, Jacob; Kjeldsen, Peter

2013-01-01

Whole-landfill methane emission was quantified using a tracer technique that combines controlled tracer gas release from the landfill with time-resolved concentration measurements downwind of the landfill using a mobile high-resolution analytical instrument. Methane emissions from 13 Danish...... landfills varied between 2.6 and 60.8 kg CH4 h–1. The highest methane emission was measured at the largest (in terms of disposed waste amounts) of the 13 landfills, whereas the lowest methane emissions (2.6-6.1 kgCH4 h–1) were measured at the older and smaller landfills. At two of the sites, which had gas...... collection, emission measurements showed that the gas collection systems only collected between 30-50% of the methane produced (assuming that the produced methane equalled the sum of the emitted methane and the collected methane). Significant methane emissions were observed from disposed shredder waste...

Biomethanation potential for co-digestion of municipal solid waste and rice straw: A batch study.

Science.gov (United States)

Negi, Suraj; Dhar, Hiya; Hussain, Athar; Kumar, Sunil

2018-04-01

Rice straw (RS) contains a high amount of lignocellulosic materials which are difficult to degrade without thermal pretreatment. In the present study, co-digestion of municipal solid waste (MSW) and RS was carried out in three different ratios i.e., 1:1, 2:1, and 3:1 to get the maximum biomethanation potential and methane generation rate constant (k). The biogas and methane (CH 4 ) potential increased by 60% and 57%, respectively for MSW and RS in the ratio 2:1 as compared to other combination. The values of k, biochemical methane potential (µ b ) and sludge activity were measured as 0.1 d -1 , 0.99 CH 4 -COD/COD fed and 0.50 g CH 4 -COD/g VSS, respectively. The sludge activity was found to be 100% for 2:1 ratio. Co-digestion of RS with MSW can also optimize the C/N ratio which is an essential parameter in the anaerobic digestion process. Copyright © 2018 Elsevier Ltd. All rights reserved.

Potential for methane production from typical Mediterranean agro-industrial by-products

Energy Technology Data Exchange (ETDEWEB)

Fountoulakis, M.S.; Drakopoulou, S.; Terzakis, S.; Georgaki, E.; Manios, T. [Laboratory of Solid Waste and Wastewater Management, School of Agricultural Technology, Technological Educational Institute of Crete, GR-71004 Iraklio, Crete (Greece)

2008-02-15

This work examines the potential for methane production from anaerobic co-digestion of olive mill wastewater and wine-grape residues with slaughterhouse wastewater. Continuous (mesophilic) and batch (mesophilic and thermophilic) experiments were studied, both with the separate types of by-products and with mixtures. Methane yields from olive oil wastewater, winery residues and slaughterhouse wastewater were 108, 147 and 297 L CH{sub 4} kg{sup -1} COD fed respectively. Co-digestion with 50% olive oil wastewater and 50% slaughterhouse wastewater or 50% winery residues gave a methane yield of 184 and 214 L CH{sub 4} kg{sup -1} COD, respectively. Furthermore, the methane yield was 188 L CH{sub 4} kg{sup -1} COD added, co-digesting a mixture of 50% winery residues and slaughterhouse wastewater. Finally, the same mixtures under thermophilic conditions gave methane yields of 282, 301 and 219 L CH{sub 4} kg{sup -1} COD, respectively. These results suggest that methane can be produced very efficiently by co-digesting olive oil wastewater, wine-grape residues and slaughterhouse wastewater. (author)

First experience with the new solid methane moderator at the IBR-2 reactor

International Nuclear Information System (INIS)

Beliakov, A.A.; Shabalin, E.P.; Tretyakov, I.T.

2001-01-01

In the 1999 Fall the solid methane moderator (CM) has been installed and tested at full power at the IBR-2 pulsed reactor. Its main features are a beryllium reflector and a light water premoderator. Radiation load on the methane was three times as much as that of IPNS facility, namely, 0.1 W/g. Effects of temperature, operation time, concentration of a hydrogen scavenger, and annealing procedure on both neutron and service performances were studied. Maximum operation time of a newly loaded portion of methane was 4 days. In this time around 30% of methane is transformed into hydrogen, ethane, and high molecular hydrocarbons, and yet no deterioration in cold neutron intensity was detected. Among new knowledge, the most important are two facts observed: two-fold decrease in hydrogen formation rate when methane is poisoned with 2.5% to 5% of ethylene, and low formation rate of solid, inremovable products of radiolysis - (1.5/3)10 -7 g/J, which means that after 10 years of operation the methane chamber will be filled with only 100 g of residue. Gain of factor 20 in cold neutron flux was obtained as compared to the routine grooved light water moderator. Presently, it is the highest among the intense pulsed neutron sources. (author)

Carbon dioxide induced bubble formation in a CH4-CO2-H2O ternary system: a molecular dynamics simulation study.

Science.gov (United States)

Sujith, K S; Ramachandran, C N

2016-02-07

The extraction of methane from its hydrates using carbon dioxide involves the decomposition of the hydrate resulting in a CH4-CO2-H2O ternary solution. Using classical molecular dynamics simulations, we investigate the evolution of dissolved gas molecules in the ternary system at different concentrations of CO2. Various compositions considered in the present study resemble the solution formed during the decomposition of methane hydrates at the initial stages of the extraction process. We find that the presence of CO2 aids the formation of CH4 bubbles by causing its early nucleation. Elucidation of the composition of the bubble revealed that in ternary solutions with high concentration of CO2, mixed gas bubbles composed of CO2 and CH4 are formed. To understand the role of CO2 in the nucleation of CH4 bubbles, the structure of the bubble formed was analyzed, which revealed that there is an accumulation of CO2 at the interface of the bubble and the surrounding water. The aggregation of CO2 at the bubble-water interface occurs predominantly when the concentration of CO2 is high. Radial distribution function for the CH4-CO2 pair indicates that there is an increasingly favorable direct contact between dissolved CH4 and CO2 molecules in the bubble-water interface. It is also observed that the presence of CO2 at the interface results in the decrease in surface tension. Thus, CO2 leads to greater stability of the bubble-water interface thereby bringing down the critical size of the bubble nuclei. The results suggest that a rise in concentration of CO2 helps in the removal of dissolved CH4 thereby preventing the accumulation of methane in the liquid phase. Thus, the presence of CO2 is predicted to assist the decomposition of methane hydrates in the initial stages of the replacement process.

Methanation of hydrogen and carbon dioxide

International Nuclear Information System (INIS)

Burkhardt, Marko; Busch, Günter

2013-01-01

Highlights: • The biologic methanation of exclusively gases like hydrogen and carbon dioxide is feasible. • Electrical energy can be stored in the established gas grid by conversion to methane. • The quality of produced biogas is very high (c CH4 = 98 vol%). • The conversion rate is depending on H 2 -flow rate. - Abstract: A new method for the methanation of hydrogen and carbon dioxide is presented. In a novel anaerobic trickle-bed reactor, biochemical catalyzed methanation at mesophilic temperatures and ambient pressure can be realized. The conversion of gaseous substrates by immobilized hydrogenotrophic methanogens is a unique feature of this reactor type. The already patented reactor produces biogas which has a very high quality (c CH4 = 97.9 vol%). Therefore, the storage of biogas in the existing natural gas grid is possible without extensive purification. The specific methane production was measured with P = 1.17 Nm CH4 3 /(m R 3 d). It is conceivable to realize the process at sites that generate solar or wind energy and sites subject to the conditions for hydrogen electrolysis (or other methods of hydrogen production). The combination with conventional biogas plants under hydrogen addition to methane enrichment is possible as well. The process enables the coupling of various renewable energy sources

Experimental study of swelling of irradiated solid methane during annealing

International Nuclear Information System (INIS)

Shabalin, E.; Fedorov, A.; Kulagin, E.; Kulikov, S.; Melikhov, V.; Shabalin, D.

2008-01-01

Solid methane, notwithstanding its poor radiation properties, is still widely in use at pulsed neutron sources. One of the specific problems is radiolytic hydrogen gas pressure on the walls of a methane chamber during annealing of methane. Results of experimental study of this phenomenon under fast neutron irradiation with the help of a specially made low temperature irradiation rig at the IBR-2 pulsed reactor are presented. Peak pressure on the wall of the experimental capsule during heating of a sample irradiated at 23-35 K appeared to have a maximum of 27 bar at the absorbed dose 20 MGy, and then falls down with higher doses. Pressure always reached its peak value within the temperature range 72-79 K. Generally, three phases of methane swelling during heating can be distinguished, each characterized by proper rate and intensity. Results of this study were accounted for in design of the solid methane moderator of the second target station of the ISIS facility (England)

Origin and Distribution of Methane Entrapped in Calcareous Alpine Proglacial Soil

Science.gov (United States)

Zhu, Biqing; Schroth, Martin H.; Henneberger, Ruth; Kübler, Manuel; Zeyer, Josef

2017-04-01

Methane (CH4) is an important greenhouse gas. The atmospheric methane concentration has been increasing in recent years, which is caused by imbalance between sources and sinks. Methane has been recently discovered to be entrapped in calcareous Swiss Alpine proglacial soil. This CH4 can be released upon mechanical impact and acidification. However, the amount, distribution and environmental fate of this entrapped CH4 in proglacial environment remain unknown. The entrapped CH4 in proglacial soil may be of modern or ancient origin. Modern origin includes ongoing or recent microbial CH4 production (methanogenesis) in subglacial or proglacial environments. An ancient origin mainly refers to CH4 produced thermogenically. This soil entrapped CH4 might be a common phenomenon along the entire glacial forefield, or it might only be present at few locations and depth. We present results of studies from two Swiss Alpine Glacier catchments, Wildstrubel Glacier (Canton Valais) and the Griessfirn Glacier (Canton Uri). Our main goals were 1) to assess the origin of CH4 entrapped in various glacial environments (subglacial, proglacial and supraglacial, soil and bedrocks) using geochemical and microbiological evidence; 2) to assess the spatial distribution of entrapped CH4. We performed geochemical analysis (CH4 content, gas wetness ([C1]/[C2-C3] alkane ratio), CH4 stable 13C- and 2H-isotopes, TOC) on subglacial, proglacial, and supraglacial soil samples collected from well-aerated and water-logged locations. Geochemical analysis was also selectively conducted on pore-water samples and on rock samples collected from different geological formations along the catchments. We also performed batch incubations on soil samples collected from subglacial, proglacial water-logged and supraglacial zones. In addition, for the aforementioned three types of samples, we also performed molecular analyses targeting the mcrA gene, which encodes the α-subunit of the enzyme methyl-coenzyme M reductase

Upconversion detector for methane atmospheric sensor

DEFF Research Database (Denmark)

Meng, Lichun; Fix, Andreas; Høgstedt, Lasse

2017-01-01

We demonstrate an efficient upconversion detector (UCD) for a methane (CH4) atmospheric sensor. The UCD shows comparable performance with a conventional detector when measuring the backscattered signal from the hard target located 2.3 km away.......We demonstrate an efficient upconversion detector (UCD) for a methane (CH4) atmospheric sensor. The UCD shows comparable performance with a conventional detector when measuring the backscattered signal from the hard target located 2.3 km away....

Methane oxidation in contrasting soil types

DEFF Research Database (Denmark)

D'Imperio, Ludovica; Nielsen, Cecilie Skov; Westergaard-Nielsen, Andreas

2017-01-01

Arctic ecosystems are characterized by a wide range of soil moisture conditions and thermal regimes and contribute differently to the net methane (CH4) budget. Yet, it is unclear how climate change will affect the capacity of those systems to act as a net source or sink of CH4. Here, we present...... subsequently scaled to the entire study area of 0.15 km2, a landscape also consisting of wetlands with a seasonally integrated methane release of 0.10 ± 0.01 g CH4-C m−2 (3.7 ± 1.2 g CO2-eq m−2). The result was a net landscape sink of 12.71 kg CH4-C (0.48 tonne CO2-eq) during the growing season...

Large methane releases lead to strong aerosol forcing and reduced cloudiness

DEFF Research Database (Denmark)

Kurten, T.; Zhou, L.; Makkonen, R.

2011-01-01

forcing that is comparable in magnitude to the long-wave radiative forcing ("enhanced greenhouse effect") of the added methane. Together, the indirect CH4-O-3 and CH4-OHaerosol forcings could more than double the warming effect of large methane increases. Our findings may help explain the anomalously......The release of vast quantities of methane into the atmosphere as a result of clathrate destabilization is a potential mechanism for rapid amplification of global warming. Previous studies have calculated the enhanced warming based mainly on the radiative effect of the methane itself, with smaller...... contributions from the associated carbon dioxide or ozone increases. Here, we study the effect of strongly elevated methane (CH4) levels on oxidant and aerosol particle concentrations using a combination of chemistry-transport and general circulation models. A 10-fold increase in methane concentrations...

Ignition-promoting effect of NO2 on methane, ethane and methane/ethane mixtures in a rapid compression machine

DEFF Research Database (Denmark)

Gersen, S.; Mokhov, A.V.; Darmeveil, J.H.

2011-01-01

Autoignition delay times of stoichiometric methane, ethane and methane/ethane mixtures doped with 100 and 270ppm of NO2 have been measured in a RCM in the temperature range 900–1050K and pressures from 25 to 50bar. The measurements show that addition of NO2 to CH4/O2/N2/Ar and CH4/C2H6/O2/N2/Ar...

Inhibition of methane oxidation in slurry surface crust by inorganic nitrogen

DEFF Research Database (Denmark)

Duan, Yun-Feng; Elsgaard, Lars; Petersen, Søren O

2013-01-01

Livestock slurry is an important source of methane (CH4). Depending on dry matter content, a floating crust may form where methane-oxidizing bacteria (MOB) and CH4 oxidation activity have been found, suggesting that surface crusts may reduce CH4 emissions from slurry. However, it is not known how...... MOB in this environment interact with inorganic nitrogen (N). We studied inhibitory effects of ammonium (NH4+), nitrate (NO3–) and nitrite (NO2–) on potential CH4 oxidation in a cattle slurry surface crust. Methane oxidation was assayed at salt concentrations up to 500 mM at 100 and 10,000 ppmv...... headspace CH4. First-order rate constants were used to evaluate the strength of inhibition. Nitrite was the most potent inhibitor, reducing methanotrophic activity by up to 70% at only 1 mM NO2–. MOB were least sensitive to NO3–, tolerating up to 30 mM NO3– at 100 ppmv CH4 and 50 mM NO3– at 10,000 ppmv CH4...

Removal of methane from compressed natural gas fueled vehicle exhaust

International Nuclear Information System (INIS)

Subramanian, S.; Kudla, R.J.; Chattha, M.S.

1992-01-01

The objective of this paper is to investigate the modes of methane (CH 4 ) removal from simulated compressed natural gas (CNG) fueled vehicle exhaust under net oxidizing, net reducing, and stoichiometric conditions. Model reaction studies were conducted. The results suggest that the oxidation of methane with oxygen contributes to the removal of methane under net oxidizing conditions. In contrast, the oxidation of methane with oxygen as well as nitric oxide contributes to its removal under net reducing conditions. The steam reforming reaction does not significantly contribute to the removal of methane. The methane conversions under net reducing conditions are higher than those observed under net oxidizing conditions. The study shows that the presence of carbon monoxide in the feed gas leads to a gradual decrease in the methane conversion with increasing redox ratio, under net oxidizing conditions. a minimum in methane conversion is observed at a redox ratio of 0. 8. The higher activity for the methane-oxygen reaction resulting from a lowering in the overall oxidation state of palladium and the contribution of the methane-nitric oxide reaction toward the removal of CH 4 appear to account for the higher CH 4 conversions observed under net reducing conditions

Precise soil management as a tool to reduce CH4 and N2O emissions from agricultural soils

NARCIS (Netherlands)

Mosquera Losada, J.; Hol, J.M.G.; Rappoldt, C.; Dolfing, J.

2007-01-01

Soil compaction stimulates the emission of nitrous oxide (N2O) and methane (CH4) from agricultural soils. N2O and CH4 are potent greenhouse gases, with a global warming potential respectively 296 times and 23 times greater than CO2.. Agricultural soils are an important source of N2O. Hence there is

Raman and FTIR spectroscopy of methane in olivine

Science.gov (United States)

Smith, A.; Oze, C.; Rossman, G. R.; Celestian, A. J.

2017-12-01

Olivine has been proposed to be a direct source of methane (CH4) in serpentinization systems and experiments. Here, Raman and Fourier Transform Infrared (FTIR) spectroscopy were used to verify the presence and abundance of CH4 in olivine samples from nine localities, including the San Carlos olivine. Raman analyses did not identify any methane in the olivine samples. As olivine is orthorhombic, three polarized FTIR spectra were obtained for the olivine samples. No methane was detected in any of the olivine samples using FTIR. Overall, olivine investigated in this study does not appear to be a primary source of methane.

Methanization potential of anaerobic biodigestion of solid food waste

Directory of Open Access Journals (Sweden)

Laís R. G. de Oliveira

Full Text Available ABSTRACT Anaerobic biodigestion of solid and semi-solid wastes has been widely used for the treatment of these residues and methane production; however, during the process (more specifically in the acidogenic phase, there is a tendency of pH reduction, an unfavorable condition to methanogenic bacteria. Thus, the present work aims to evaluate the methanization potential of an agroindustrial anaerobic granular sludge (AIS from UASB (Upflow Anaerobic Sludge Blanket reactor, individually and biodigested with food waste (FW from the University Restaurant of the Federal University of Pernambuco with buffering agent (AIS + FW + b and without it (AIS + FW. After the laboratory tests, the AIS + FW + b configuration obtained a cumulative methane production approximately six times greater than that of AIS + FW, and approximately twice that of the inoculum alone (AIS.

Methane uptake by a selection of soils in Ghana with different land use

DEFF Research Database (Denmark)

Priemé, Anders; Christensen, Søren

1999-01-01

, the methane oxidation rates in the tropical forest and savanna soils were low (range from 9 to 26 µg CH4 m-2 h-1) compared to, for example temperate forest soils. In the savanna soil, annual fire had decreased soil methane oxidation rates to 5 µg CH4 m-2 h-1 compared to 9 µg CH4 m-2 h-1 at a site...... not subjected to fire for 6 years. In paired sites of moist forest and arable soils, methane oxidation rates were lower by >60% in the arable soils. Methane oxidation rates in three arable soils in the savanna zone soils ranged from 7 to 11 µg CH4 m-2 h-1 before the first rain but increased to 23-28 µg CH4 m-2......We measured the oxidation of atmospheric methane in tropical soils in Ghana covering a moisture gradient from the moist forest zone to the savanna zone at the onset of the rainy season. Land use at the sites covered undisturbed (forest and savanna) and cultivated soil, including burning. Generally...

Electrochemical and partial oxidation of methane

Science.gov (United States)

Singh, Rahul

2008-10-01

negligible coke formation on the novel fabricated anode by electroless plating process. Hydrogen is an environmentally cleaner source of energy. The recent increase in the demand of hydrogen as fuel for all types of fuel cells and petroleum refining process has boosted the need of production of hydrogen. Methane, a major component of natural gas is the major feedstock for production of hydrogen. The route of partial oxidation of methane to produce syngas (CO + H2) offers significant advantages over commercialized steam reforming process for higher efficiency and lower energy requirements. Partial oxidation of methane was studied by pulsing O2 into a CH4 flow over Rh/Al2O3 in a sequence of in situ infrared (IR) cell and fixed bed reactor at 773 K. The results obtained from the sequence of an IR cell followed by a fixed bed reactor show that (i) adsorbed CO produced possesses a long residence time, indicating that adsorbed oxygen leading to the formation of CO is significantly different from those leading to CO2 and (ii) CO2 is not an intermediate species for the formation of CO. In situ IR of pulse reaction coupled with alternating reactor sequence is an effective approach to study the primary and secondary reactions as well as the nature of their adsorbed species. As reported earlier, hydrogen remains to be the most effective fuel for fuel cells, the production of high purity hydrogen from naturally available resources such as coal, petroleum, and natural gas requires a number of energy-intensive steps, making fuel cell processes for stationary electric power generation prohibitively uneconomic. Direct use of coal or coal gas as the feed is a promising approach for low cost electricity generation. Coal gas solid oxide fuel cell was studied by pyrolyzing Ohio #5 coal to coal gas and transporting to a Cu anode solid oxide fuel cell to generate power. The study of coal-gas solid oxide fuel cell is divided into two sections, i.e., (i) understanding the composition of coal gas by

Activation of CH4 by Th(+) as studied by guided ion beam mass spectrometry and quantum chemistry.

Science.gov (United States)

Cox, Richard M; Armentrout, P B; de Jong, Wibe A

2015-04-06

The reaction of atomic thorium cations with CH4 (CD4) and the collision-induced dissociation (CID) of ThCH4(+) with Xe are studied using guided ion beam tandem mass spectrometry. In the methane reactions at low energies, ThCH2(+) (ThCD2(+)) is the only product; however, the energy dependence of the cross-section is inconsistent with a barrierless exothermic reaction as previously assumed on the basis of ion cyclotron resonance mass spectrometry results. The dominant product at higher energies is ThH(+) (ThD(+)), with ThCH3(+) (ThCD3(+)) having a similar threshold energy. The latter product subsequently decomposes at still higher energies to ThCH(+) (ThCD(+)). CID of ThCH4(+) yields atomic Th(+) as the exclusive product. The cross-sections of all product ions are modeled to provide 0 K bond dissociation energies (in eV) of D0(Th(+)-H) ≥ 2.25 ± 0.18, D0(Th(+)-CH) = 6.19 ± 0.16, D0(Th(+)-CH2) ≥ 4.54 ± 0.09, D0(Th(+)-CH3) = 2.60 ± 0.30, and D0(Th(+)-CH4) = 0.47 ± 0.05. Quantum chemical calculations at several levels of theory are used to explore the potential energy surfaces for activation of methane by Th(+), and the effects of spin-orbit coupling are carefully considered. When spin-orbit coupling is explicitly considered, a barrier for C-H bond activation that is consistent with the threshold measured for ThCH2(+) formation (0.17 ± 0.02 eV) is found at all levels of theory, whereas this barrier is observed only at the BHLYP and CCSD(T) levels otherwise. The observation that the CID of the ThCH4(+) complex produces Th(+) as the only product with a threshold of 0.47 eV indicates that this species has a Th(+)(CH4) structure, which is also consistent with a barrier for C-H bond activation. This barrier is thought to exist as a result of the mixed ((4)F,(2)D) electronic character of the Th(+) J = (3)/2 ground level combined with extensive spin-orbit effects.

ISLSCP II GlobalView: Atmospheric Methane Concentrations

Data.gov (United States)

National Aeronautics and Space Administration — ABSTRACT: The GlobalView Methane (CH4) data product contains synchronized and smoothed time series of atmospheric CH4 concentrations at selected sites that were...

Methane emissions form terrestrial plants

Energy Technology Data Exchange (ETDEWEB)

Bergamaschi, P.; Dentener, F.; Grassi, G.; Leip, A.; Somogyi, Z.; Federici, S.; Seufert, G.; Raes, F. [European Commission, DG Joint Research Centre, Institute for Environment and Sustainability, Ispra (Italy)

2006-07-01

In a recent issue of Nature Keppler et al. (2006) report the discovery that terrestrial plants emit CH4 under aerobic conditions. Until now it was thought that bacterial decomposition of plant material under anaerobic conditions, such as in wetlands and water flooded rice paddies, is the main process leading to emissions from terrestrial ecosystems. In a first attempt to upscale these measurements, the authors estimate that global total emissions may be 149 Tg CH4/yr (62-236 Tg CH4/yr), with the main contribution estimated from tropical forests and grasslands (107 Tg CH4/yr with a range of 46-169 Tg CH4/yr). If confirmed, this new source of emission would constitute a significant fraction of the total global methane sources (estimated 500-600 Tg CH4/yr for present day total natural and anthropogenic sources) and have important implications for the global CH4 budget. To accommodate it within the present budget some sources would need to be re-assessed downwards and/or some sinks re-assessed upwards. Furthermore, also considering that methane is a {approx}23 times more powerful greenhouse gas than CO2, the possible feedbacks of these hitherto unknown CH4 emissions on global warming and their impacts on greenhouse gases (GHG) mitigation strategies need to be carefully evaluated. The merit of the paper is without doubt related to the remarkable discovery of a new process of methane emissions active under aerobic conditions. However, we think that the applied approach of scaling up emissions from the leaf level to global totals by using only few measured data (mainly from herbaceous species) and the Net Primary Productivity of the main biomes is scientifically questionable and tends to overestimate considerably the global estimates, especially for forest biomes. Furthermore, some significant constraints on the upper limit of the global natural CH4 emissions arise from the pre-industrial CH4 budget. Pre-industrial atmospheric CH4 mixing ratios have been measured

Methane oxidation in anoxic lake waters

Science.gov (United States)

Su, Guangyi; Zopfi, Jakob; Niemann, Helge; Lehmann, Moritz

2017-04-01

Freshwater habitats such as lakes are important sources of methante (CH4), however, most studies in lacustrine environments so far provided evidence for aerobic methane oxidation only, and little is known about the importance of anaerobic oxidation of CH4 (AOM) in anoxic lake waters. In marine environments, sulfate reduction coupled to AOM by archaea has been recognized as important sinks of CH4. More recently, the discorvery of anaerobic methane oxidizing denitrifying bacteria represents a novel and possible alternative AOM pathway, involving reactive nitrogen species (e.g., nitrate and nitrite) as electron acceptors in the absence of oxygen. We investigate anaerobic methane oxidation in the water column of two hydrochemically contrasting sites in Lake Lugano, Switzerland. The South Basin displays seasonal stratification, the development of a benthic nepheloid layer and anoxia during summer and fall. The North Basin is permanently stratified with anoxic conditions below 115m water depth. Both Basins accumulate seasonally (South Basin) or permanently (North Basin) large amounts of CH4 in the water column below the chemocline, providing ideal conditions for methanotrophic microorganisms. Previous work revealed a high potential for aerobic methane oxidation within the anoxic water column, but no evidence for true AOM. Here, we show depth distribution data of dissolved CH4, methane oxidation rates and nutrients at both sites. In addition, we performed high resolution phylogenetic analyses of microbial community structures and conducted radio-label incubation experiments with concentrated biomass from anoxic waters and potential alternative electron acceptor additions (nitrate, nitrite and sulfate). First results from the unamended experiments revealed maximum activity of methane oxidation below the redoxcline in both basins. While the incubation experiments neither provided clear evidence for NOx- nor sulfate-dependent AOM, the phylogenetic analysis revealed the

Methane Dynamics in Flooded Lands

Science.gov (United States)

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...

The Global Methane Budget 2000-2012

Science.gov (United States)

Saunois, Marielle; Bousquet, Philippe; Poulter, Benjamin; Peregon, Anna; Ciais, Philippe; Canadell, Josep G.; Dlugokencky, Edward J.; Etiope, Giuseppe; Bastviken, David; Houweling, Sander;

ISLSCP II GlobalView: Atmospheric Methane Concentrations

Data.gov (United States)

National Aeronautics and Space Administration — The GlobalView Methane (CH4) data product contains synchronized and smoothed time series of atmospheric CH4 concentrations at selected sites that were created using...

Comparison of atmospheric CH4 concentration observed by GOSAT and in-situ measurements in Thailand and India

Science.gov (United States)

Hayashida, S.; Ono, A.; Ishikawa, S.; Terao, Y.; Takeuchi, W.

2012-12-01

The concentration of atmospheric methane (CH4) has more than doubled since pre-industrial levels and the observed long-term changes in the CH4 concentration have been attributed to anthropogenic activity. However, despite the importance of atmospheric CH4 in global warming, the strength of individual sources of CH4 remains highly uncertain [e.g.,Dlugokencky et al., 2011]. To characterize and quantify the emissions of CH4 especially in Monsoon Asia and Siberia, which are the most important regions as CH4 source, we started a new project, "Characterization and Quantification of global methane emissions by utilizing GOSAT and in-situ measurements " by support of the Environment Research and Technology Development Fund (ERTDF) from June 2012 under the umbrella of Ministry of Environment Japan. The projects includes (1) satellite data applications, (2) in-situ measurements in Siberia, over Western Pacific and in Monsoon Asia, (3) development of the inverse model to derive CH4 emissions by top-down approach, and (4) flux measurements in Siberia and Asia to improve the bottom-up inventories. As an initiatory approach in the project, we started air sampling in Thailand and India where there are only a few CH4 data of direct sampling with high precision. We took eight air samples at Kohn Kaen and Pimai in Thailand on June 9 and 10, 2012. The high CH4 concentration near rice paddy field contrasted to the lower CH4 concentration near Cassava field. We are planning to take more samples in India in mid-August. The satellite CH4 data including GOSAT and SCIAMACHY are also compared with the Land Surface Water Coverage (LSWC) and the Normalized Difference Vegetation Index (NDVI). The analysis revealed the seasonal variation in of xCH4 is closely related to the variation of the LSWC, coupled with NDVI. However, the satellite measurements are all column-averaged mixing ratio (xCH4), and therefore do not necessarily reflect high CH4 concentration near the surface over the emission

The c2d Spitzer spectroscopic survey of ices around low-mass young stellar objects. III. CH4

NARCIS (Netherlands)

Oberg, Karin I.; Boogert, A. C. Adwin; Pontoppidan, Klaus M.; Blake, Geoffrey A.; Evans, Neal J.; Lahuis, Fred; van Dishoeck, Ewine F.

2008-01-01

CH4 is proposed to be the starting point of a rich organic chemistry. Solid CH4 abundances have previously been determined mostly toward high-mass star-forming regions. Spitzer IRS now provides a unique opportunity to probe solid CH4 toward low-mass star-forming regions as well. Infrared spectra

Thermodynamic and structural study of two-dimensional melting within monolayers or rare gases or methane physically adsorbed upon the surface of layer-like solids

International Nuclear Information System (INIS)

Tessier, Christine

1983-01-01

The 2D (two-dimensional) melting of monolayers of rare gases or methane physically adsorbed on the basal face of lamellar solids (graphite, boron nitride and lamellar halides) has been studied. Two different experimental measurements have been made: i) adsorption isotherms; ii) neutron diffraction spectra. The main part of this report deals with the 2D liquid-incommensurate solid transition within monolayers of rare gases or methane adsorbed on the basal face of lamellar halides. This transition is first order. It is observed only if certain conditions of dimensional incompatibility between the substrate and the absorbate are fulfilled. It is little affected by the structure of the underlying substrate. A number of thermodynamic parameters associated with it, are constants once properly scaled. These constants agree well with theoretical estimates for 6-12 Lennard Jones particles adsorbed on a smooth surface. For the monolayer of Xe adsorbed on graphite the temperature of the tricritical point above which melting becomes a continuous transition has been measured. The isotope effect associated with 2D melting has been investigated by comparing the behaviour of monolayers of CH 4 and CD 4 adsorbed on boron nitride. The vapor pressure of Xe has been determined in the temperature range 101-120 K. (author) [fr

Macromolecule simulation and CH{sub 4} adsorption mechanism of coal vitrinite

Energy Technology Data Exchange (ETDEWEB)

Yu, Song, E-mail: songyu10094488@126.com [School of Resources and Earth Science, China University of Mining & Technology, Xuzhou 221116 (China); Key Laboratory of Coal bed Methane Resource & Reservoir Formation Process, Ministry of Education, Xuzhou 221008 (China); Yan-ming, Zhu; Wu, Li [School of Resources and Earth Science, China University of Mining & Technology, Xuzhou 221116 (China); Key Laboratory of Coal bed Methane Resource & Reservoir Formation Process, Ministry of Education, Xuzhou 221008 (China)

2017-02-28

Highlights: • Molecular model of single maceral vitrinite was obtained by {sup 13}C NMR, FT IR and HRTEM. • An optimal configuration was obtained through calculation of MM and MD. • The adsorption parameters for methane and vitrinite were determined with DFT and GCMC. - Abstract: The microscopic mechanism of interactions between CH{sub 4} and coal macromolecules is of significant practical and theoretical importance in CBM development and methane storage. Under periodic boundary conditions, the optimal energy configuration of coal vitrinite, which has a higher torsion degree and tighter arrangement, can be determined by the calculation of molecular mechanics (MM) and molecular dynamics (MD), and annealing kinetics simulation based on ultimate analysis, {sup 13}C NMR, FT IR and HRTEM. Macromolecular stabilization is primarily due to the van der Waals energy and covalent bond energy, mainly consisting of bond torsion energy and bond angle energy. Using the optimal configuration as the adsorbent, GCMC simulation of vitrinite adsorption of CH{sub 4} is conducted. A saturated state is reached after absorbing 17 CH{sub 4}s per coal vitrinite molecule. CH{sub 4} is preferentially adsorbed on the edge, and inclined to gathering around the branched chains of the inner vitrinite sites. Finally, the adsorption parameters are calculated through first principle DFT. The adsorbability order is as follows: aromatic structure> heteroatom rings > oxygen functional groups. The adsorption energy order is as follows: Top < Bond < Center, Up < Down. The order of average RDF better reflects the adsorption ability and that of [-COOH] is lower than those of [−C=O] and [C−O−C]. CH{sub 4} distributed in the distance of 0.99–16 Å to functional groups in the type of monolayer adsorption and the average distance order manifest as [−C=O] (1.64 Å) < [C−O−C] (1.89 Å) < [−COOH] (3.78 Å) < [-CH{sub 3}] (4.11 Å) according to the average RDF curves. CH{sub 4} enriches

Regional landfills methane emission inventory in Malaysia.

Science.gov (United States)

Abushammala, Mohammed F M; Noor Ezlin Ahmad Basri; Basri, Hassan; Ahmed Hussein El-Shafie; Kadhum, Abdul Amir H

2011-08-01

The decomposition of municipal solid waste (MSW) in landfills under anaerobic conditions produces landfill gas (LFG) containing approximately 50-60% methane (CH(4)) and 30-40% carbon dioxide (CO(2)) by volume. CH(4) has a global warming potential 21 times greater than CO(2); thus, it poses a serious environmental problem. As landfills are the main method for waste disposal in Malaysia, the major aim of this study was to estimate the total CH(4) emissions from landfills in all Malaysian regions and states for the year 2009 using the IPCC, 1996 first-order decay (FOD) model focusing on clean development mechanism (CDM) project applications to initiate emission reductions. Furthermore, the authors attempted to assess, in quantitative terms, the amount of CH(4) that would be emitted from landfills in the period from 1981-2024 using the IPCC 2006 FOD model. The total CH(4) emission using the IPCC 1996 model was estimated to be 318.8 Gg in 2009. The Northern region had the highest CH(4) emission inventory, with 128.8 Gg, whereas the Borneo region had the lowest, with 24.2 Gg. It was estimated that Pulau Penang state produced the highest CH(4) emission, 77.6 Gg, followed by the remaining states with emission values ranging from 38.5 to 1.5 Gg. Based on the IPCC 1996 FOD model, the total Malaysian CH( 4) emission was forecast to be 397.7 Gg by 2020. The IPCC 2006 FOD model estimated a 201 Gg CH(4) emission in 2009, and estimates ranged from 98 Gg in 1981 to 263 Gg in 2024.

Optimization of solid state anaerobic digestion of the OFMSW by digestate recirculation: A new approach

International Nuclear Information System (INIS)

Michele, Pognani; Giuliana, D’Imporzano; Carlo, Minetti; Sergio, Scotti; Fabrizio, Adani

2015-01-01

Highlights: • Solid State Anaerobic Digestion (SSAD) of OFMSW can be optimized by irrigation with digestate. • Digestate spreading allows keeping optimal process parameters and high hydrolysis rate. • The 18.4% of CH 4 was produced in the reactor, leaving the 49.7% in the percolate. • Successive CSTR feed with percolate shows a biogas enriched in methane (more than 80%). • The proposed process allow producing the 68% of OFMSW potential CH 4 , getting high quality organic amendment. - Abstract: Dry anaerobic digestion (AD) of OFMSW was optimized in order to produce biogas avoiding the use of solid inoculum. Doing so the dry AD was performed irrigating the solid waste with liquid digestate (flow rate of 1:1.18–1:0.9 w/w waste/digestate; 21 d of hydraulic retention time – HRT) in order to remove fermentation products inhibiting AD process. Results indicated that a high hydrolysis rate of organic matter (OM) and partial biogas production were obtained directly during the dry AD. Hydrolysate OM was removed from digester by the percolate flow and it was subsequently used to feed a liquid anaerobic digester. During dry AD a total loss of 36.9% of total solids was recorded. Methane balance indicated that 18.4% of potential methane can be produced during dry AD and 49.7% by the percolate. Nevertheless results obtained for liquid AD digestion indicated that only 20.4% and 25.7% of potential producible methane was generated by adopting 15 and 20 days of HRT, probably due to the AD inhibition due to high presence of toxic ammonia forms in the liquid medium

Optimization of solid state anaerobic digestion of the OFMSW by digestate recirculation: A new approach

Energy Technology Data Exchange (ETDEWEB)

Michele, Pognani, E-mail: michele.pognani@unimi.it [Gruppo Ricicla – DiSAA, Università degli Studi di Milano, Soil and Env. Lab, Via Celoria, 2, 20133 Milano (Italy); Giuliana, D’Imporzano, E-mail: giuliana.dimporzano@unimi.it [Gruppo Ricicla – DiSAA, Università degli Studi di Milano, Soil and Env. Lab, Via Celoria, 2, 20133 Milano (Italy); Gruppo Ricicla - DiSAA, Università degli Studi di Milano, Biomass and Bioenergy Lab., Parco Tecnologico Padano, Via Einstein, Loc. C.na Codazza, 26900 Lodi (Italy); Carlo, Minetti, E-mail: carlo.minetti@a2a.eu [Ecodeco, a2a Group, Cascina Darsena 1, 27010 Giussago, Pavia (Italy); Sergio, Scotti, E-mail: sergio.scotti@a2a.eu [Ecodeco, a2a Group, Cascina Darsena 1, 27010 Giussago, Pavia (Italy); Fabrizio, Adani, E-mail: farbrizio.adani@unimi.it [Gruppo Ricicla – DiSAA, Università degli Studi di Milano, Soil and Env. Lab, Via Celoria, 2, 20133 Milano (Italy); Gruppo Ricicla - DiSAA, Università degli Studi di Milano, Biomass and Bioenergy Lab., Parco Tecnologico Padano, Via Einstein, Loc. C.na Codazza, 26900 Lodi (Italy)

2015-01-15

Highlights: • Solid State Anaerobic Digestion (SSAD) of OFMSW can be optimized by irrigation with digestate. • Digestate spreading allows keeping optimal process parameters and high hydrolysis rate. • The 18.4% of CH{sub 4} was produced in the reactor, leaving the 49.7% in the percolate. • Successive CSTR feed with percolate shows a biogas enriched in methane (more than 80%). • The proposed process allow producing the 68% of OFMSW potential CH{sub 4}, getting high quality organic amendment. - Abstract: Dry anaerobic digestion (AD) of OFMSW was optimized in order to produce biogas avoiding the use of solid inoculum. Doing so the dry AD was performed irrigating the solid waste with liquid digestate (flow rate of 1:1.18–1:0.9 w/w waste/digestate; 21 d of hydraulic retention time – HRT) in order to remove fermentation products inhibiting AD process. Results indicated that a high hydrolysis rate of organic matter (OM) and partial biogas production were obtained directly during the dry AD. Hydrolysate OM was removed from digester by the percolate flow and it was subsequently used to feed a liquid anaerobic digester. During dry AD a total loss of 36.9% of total solids was recorded. Methane balance indicated that 18.4% of potential methane can be produced during dry AD and 49.7% by the percolate. Nevertheless results obtained for liquid AD digestion indicated that only 20.4% and 25.7% of potential producible methane was generated by adopting 15 and 20 days of HRT, probably due to the AD inhibition due to high presence of toxic ammonia forms in the liquid medium.

Thermophilic co-digestion feasibility of distillers grains and swine manure: effect of C/N ratio and organic loading rate during high solid anaerobic digestion (HSAD).

Science.gov (United States)

Sensai, P; Thangamani, A; Visvanathan, C

2014-01-01

Anaerobic co-digestion of high solids containing distillers grains and swine manure (total solids, 27 +/- 2% and 18 +/- 2%, respectively) was evaluated in this study to assess the effect of C/N ratio and organic loading rate (OLR). Feed mixture was balanced to achieve a C/N ratio of 30/1 by mixing distillers grains and swine manure. Pilot-scale co-digestion of distillers grains and swine manure was carried out under thermophilic conditions in the continuous mode for seven different OLRs from R1 to R7 (3.5, 5, 6, 8, 10, 12 and 14 kg VS/m3 day) under high solid anaerobic digestion. The methane yield and volatile solid (VS) removal were consistent; ranging from 0.33 to 0.34 m3CH4/kg VS day and 50-53%, respectively, until OLR 8 kg VS/m3 day. After which methane yield and VS removal significantly decreased to 0.26 m3 CH4/kg VS day and 42%, respectively, when OLR was increased to 14 kg VS/m3 day. However, during operation, at OLR of 10 kg VS/m3 day, the methane yield and VS removal increased after the 19th day to 0.33 m3 CH4/kg VS day and 46%, respectively, indicating that a longer acclimatization period is required by methanogens at a higher loading rate.

Titan's methane clock

Science.gov (United States)

Nixon, C. A.; Jennings, D. E.; Romani, P. N.; Teanby, N. A.; Irwin, P. G. J.; Flasar, F. M.

2010-04-01

Measurements of the 12C/13C and D/H isotopic ratios in Titan's methane show intriguing differences from the values recorded in the giant planets. This implies that either (1) the atmosphere was differently endowed with material at the time of formation, or (2) evolutionary processes are at work in the moon's atmosphere - or some combination of the two. The Huygens Gas Chromatograph Mass Spectrometer Instrument (GCMS) found 12CH4/13CH4 = 82 +/- 1 (Niemann et al. 2005), some 7% lower than the giant planets' value of 88 +/- 7 (Sada et al. 1996), which closely matches the terrestrial inorganic standard of 89. The Cassini Composite Infrared Spectrometer (CIRS) has previously reported 12CH4/13CH4 of 77 +/-3 based on nadir sounding, which we now revise upwards to 80 +/- 4 based on more accurate limb sounding. The CIRS and GCMS results are therefore in agreement about an overall enrichment in 13CH4 of ~10%. The value of D/H in Titan's CH4 has long been controversial: historical measurements have ranged from about 8-15 x 10-5 (e.g. Coustenis et al. 1989, Coustenis et al. 2003). A recent measurement based on CIRS limb data by Bezard et al. (2007) puts the D/H in CH4 at (13 +/- 1) x 10-5, very much greater than in Jupiter and Saturn, ~2 x 10-5 (Mahaffy et al. 1998, Fletcher et al. 2009). To add complexity, the 12C/13C and D/H vary among molecules in Titan atmosphere, typically showing enhancement in D but depletion in 13C in the daughter species (H2, C2H2, C2H6), relative to the photochemical progenitor, methane. Jennings et al. (2009) have sought to interpret the variance in carbon isotopes as a Kinetic Isotope Effect (KIE), whilst an explanation for the D/H in all molecules remains elusive (Cordier et al. 2008). In this presentation we argue that evolution of isotopic ratios in Titan's methane over time forms a ticking 'clock', somewhat analogous to isotopic ratios in geochronology. Under plausible assumptions about the initial values and subsequent replenishment, various

Methane Feedbacks to the Global Climate System in a Warmer World

Science.gov (United States)

Dean, Joshua F.; Middelburg, Jack J.; Röckmann, Thomas; Aerts, Rien; Blauw, Luke G.; Egger, Matthias; Jetten, Mike S. M.; de Jong, Anniek E. E.; Meisel, Ove H.; Rasigraf, Olivia; Slomp, Caroline P.; in't Zandt, Michiel H.; Dolman, A. J.

2018-03-01

Methane (CH4) is produced in many natural systems that are vulnerable to change under a warming climate, yet current CH4 budgets, as well as future shifts in CH4 emissions, have high uncertainties. Climate change has the potential to increase CH4 emissions from critical systems such as wetlands, marine and freshwater systems, permafrost, and methane hydrates, through shifts in temperature, hydrology, vegetation, landscape disturbance, and sea level rise. Increased CH4 emissions from these systems would in turn induce further climate change, resulting in a positive climate feedback. Here we synthesize biological, geochemical, and physically focused CH4 climate feedback literature, bringing together the key findings of these disciplines. We discuss environment-specific feedback processes, including the microbial, physical, and geochemical interlinkages and the timescales on which they operate, and present the current state of knowledge of CH4 climate feedbacks in the immediate and distant future. The important linkages between microbial activity and climate warming are discussed with the aim to better constrain the sensitivity of the CH4 cycle to future climate predictions. We determine that wetlands will form the majority of the CH4 climate feedback up to 2100. Beyond this timescale, CH4 emissions from marine and freshwater systems and permafrost environments could become more important. Significant CH4 emissions to the atmosphere from the dissociation of methane hydrates are not expected in the near future. Our key findings highlight the importance of quantifying whether CH4 consumption can counterbalance CH4 production under future climate scenarios.

Raman spectroscopic characterization of CH4 density over a wide range of temperature and pressure

Science.gov (United States)

Shang, Linbo; Chou, I-Ming; Burruss, Robert; Hu, Ruizhong; Bi, Xianwu

2014-01-01

The positions of the CH4 Raman ν1 symmetric stretching bands were measured in a wide range of temperature (from −180 °C to 350 °C) and density (up to 0.45 g/cm3) using high-pressure optical cell and fused silica capillary capsule. The results show that the Raman band shift is a function of both methane density and temperature; the band shifts to lower wavenumbers as the density increases and the temperature decreases. An equation representing the observed relationship among the CH4 ν1 band position, temperature, and density can be used to calculate the density in natural or synthetic CH4-bearing inclusions.

Microbial CH4 and N2O consumption in acidic wetlands

Directory of Open Access Journals (Sweden)

Steffen eKolb

2012-03-01

Full Text Available Acidic wetlands are global sources of the atmospheric greenhouse gases methane (CH4, and nitrous oxide (N2O. Consumption of both atmospheric gases has been observed in various acidic wetlands, but information on the microbial mechanisms underlying these phenomena is scarce. A substantial amount of CH4 is consumed in sub soil by aerobic methanotrophs at anoxic–oxic interfaces (e.g., tissues of Sphagnum mosses, rhizosphere of vascular plant roots. Methylocystis-related species are likely candidates that are involved in the consumption of atmospheric CH4 in acidic wetlands. Oxygen availability regulates the activity of methanotrophs of acidic wetlands. Other parameters impacting on the methanotroph-mediated CH4 consumption have not been systematically evaluated. N2O is produced and consumed by microbial denitrification, thus rendering acidic wetlands as temporary sources or sinks for N2O. Denitrifier communities in such ecosystems are diverse, and largely uncultured and/or new, and environmental factors that control their consumption activity are unresolved. Analyses of the composition of N2O reductase genes in acidic wetlands suggest that acid-tolerant Proteobacteria have the potential to mediate N2O consumption in such soils. Thus, the fragmented current state of knowledge raises open questions concerning methanotrophs and dentrifiers that consume atmospheric CH4 and N2O in acidic wetlands.

Diurnal and seasonal variations in CH4 emission from various freshwater wetlands

International Nuclear Information System (INIS)

Kim, J.; Kim, J.-W.; Verma, B.; Shurpali, N.J.; Harazono, Y.; Miyata, A.; Yun, J.-I.; Tanner, B.

2000-01-01

Recent evidence indicates that future increases in atmospheric CO2 concentration may lead to significant increases in methane emissions from wetlands. Based on the concurrent eddy covariance measurements of CH4 and ecosystem production in freshwater wetlands. Also, we briefly discuss the current concerns of the micrometeorological community on the long-term monitoring of these greenhouse gases. 16 refs

Experimental workflow for developing a feed forward strategy to control biomass growth and exploit maximum specific methane productivity of Methanothermobacter marburgensis in a biological methane production process (BMPP

Directory of Open Access Journals (Sweden)

Alexander Krajete

2016-08-01

Full Text Available Recently, interests for new biofuel generations allowing conversion of gaseous substrate(s to gaseous product(s arose for power to gas and waste to value applications. An example is biological methane production process (BMPP with Methanothermobacter marburgensis. The latter, can convert carbon dioxide (CO2 and hydrogen (H2, having different origins and purities, to methane (CH4, water and biomass. However, these gas converting bioprocesses are tendentiously gas limited processes and the specific methane productivity per biomass amount (qCH4 tends to be low. Therefore, this contribution proposes a workflow for the development of a feed forward strategy to control biomass, growth (rx and qCH4 in a continuous gas limited BMPP. The proposed workflow starts with a design of experiment (DoE to optimize media composition and search for a liquid based limitation to control selectively growth. From the DoE it came out that controlling biomass growth was possible independently of the dilution and gassing rate applied while not affecting methane evolution rates (MERs. This was done by shifting the process from a natural gas limited state to a controlled liquid limited growth. The latter allowed exploiting the maximum biocatalytic activity for methane formation of Methanothermobacter marburgensis. An increase of qCH4 from 42 to 129 mmolCH4 g−1 h−1 was achieved by applying a liquid limitation compare with the reference state. Finally, a verification experiment was done to verify the feeding strategy transferability to a different process configuration. This evidenced the ratio of the fed KH2PO4 to rx (R(FKH2PO4/rx has an appropriate parameter for scaling feeds in a continuous gas limited BMPP. In the verification experiment CH4 was produced in a single bioreactor step at a methane evolution rate (MER of   132 mmolCH4*L−1*h−1 at a CH4 purity of 93 [Vol.%].

Decomposition of methane hydrate for hydrogen production using microwave and radio frequency in-liquid plasma methods

International Nuclear Information System (INIS)

Rahim, Ismail; Nomura, Shinfuku; Mukasa, Shinobu; Toyota, Hiromichi

2015-01-01

This research involves two in-liquid plasma methods of methane hydrate decomposition, one using radio frequency wave (RF) irradiation and the other microwave radiation (MW). The ultimate goal of this research is to develop a practical process for decomposition of methane hydrate directly at the subsea site for fuel gas production. The mechanism for methane hydrate decomposition begins with the dissociation process of methane hydrate formed by CH_4 and water. The process continues with the simultaneously occurring steam methane reforming process and methane cracking reaction, during which the methane hydrate is decomposed releasing CH_4 into H_2, CO and other by-products. It was found that methane hydrate can be decomposed with a faster rate of CH_4 release using microwave irradiation over that using radio frequency irradiation. However, the radio frequency plasma method produces hydrogen with a purity of 63.1% and a CH conversion ratio of 99.1%, which is higher than using microwave plasma method which produces hydrogen with a purity of 42.1% and CH_4 conversion ratio of 85.5%. - Highlights: • The decomposition of methane hydrate is proposed using plasma in-liquid method. • Synthetic methane hydrate is used as the sample for decomposition in plasma. • Hydrogen can be produced from decomposition of methane hydrate. • Hydrogen purity is higher when using radio frequency stimulation.

Macromolecule simulation and CH4 adsorption mechanism of coal vitrinite

Science.gov (United States)

Yu, Song; Yan-ming, Zhu; Wu, Li

2017-02-01

The microscopic mechanism of interactions between CH4 and coal macromolecules is of significant practical and theoretical importance in CBM development and methane storage. Under periodic boundary conditions, the optimal energy configuration of coal vitrinite, which has a higher torsion degree and tighter arrangement, can be determined by the calculation of molecular mechanics (MM) and molecular dynamics (MD), and annealing kinetics simulation based on ultimate analysis, 13C NMR, FT IR and HRTEM. Macromolecular stabilization is primarily due to the van der Waals energy and covalent bond energy, mainly consisting of bond torsion energy and bond angle energy. Using the optimal configuration as the adsorbent, GCMC simulation of vitrinite adsorption of CH4 is conducted. A saturated state is reached after absorbing 17 CH4s per coal vitrinite molecule. CH4 is preferentially adsorbed on the edge, and inclined to gathering around the branched chains of the inner vitrinite sites. Finally, the adsorption parameters are calculated through first principle DFT. The adsorbability order is as follows: aromatic structure> heteroatom rings > oxygen functional groups. The adsorption energy order is as follows: Top graphene. However, the energy of the most preferential location is much lower than that of graphite/graphene. CH4 is more easily absorbed on the surface of vitrinite. Adsorbability varies considerably at different adsorption locations and sites on the surface of vitrinite. Crystal parameter of vitrinite is a = b = c = 15.8 Å and majority of its micropores are blow 15.8 Å, indicating that the vitrinite have the optimum adsorption aperture. It can explain its higher observed adsorption capacities for CH4 compared with graphite/graphene.

Methane-induced Activation Mechanism of Fused Ferric Oxide-Alumina Catalysts during Methane Decomposition

KAUST Repository

Reddy Enakonda, Linga; Zhou, Lu; Saih, Youssef; Ould-Chikh, Samy; Lopatin, Sergei; Gary, Daniel; Del-Gallo, Pascal; Basset, Jean-Marie

2016-01-01

Activation of Fe2O3-Al2O3 with CH4 (instead of H2) is a meaningful method to achieve catalytic methane decomposition (CMD). This reaction of CMD is more economic and simple against commercial methane steam reforming (MSR) as it produces COx-free H2

Continuous flow IRMS application to CH4, MNHCS, and N2O in the atmosphere and the oceans

International Nuclear Information System (INIS)

Yoshida, N.; Tsunogai, U.; Toyoda, S.

2001-01-01

The application of CF-IRMS to measurement of methane (CH4), non-methane hydrocarbons (NMHCS), and nitrous oxide (N 2 O) is outlined and preliminary information on isotopic variations in the atmosphere and oceans is presented. Labelling of these compounds is expected to provide a robust method for tracing sources, sinks and controlling processes in the environment. (author)

MICROBIAL DIVERSITY AS A CONTROLLING FACTOR OF AEROBIC METHANE CONSUMPTION

NARCIS (Netherlands)

Bodelier, P.L.E.; Meima-Franke, M.; Hordijk, C.A.; Steenbergh, A.K.

2010-01-01

Background. Aerobic methane oxidizing bacteria (MOB) play a vital role in the global climate by degrading the greenhouse gas CH4. The process of CH4 consumption is sensitive to disturbance leading to strong variability in CH4 emission from ecosystems. Mechanistic explanations for variability in CH4

Kinetics of biological methane oxidation in the presence of non-methane organic compounds in landfill bio-covers

International Nuclear Information System (INIS)

Albanna, Muna; Warith, Mostafa; Fernandes, Leta

2010-01-01

In this experimental program, the effects of non-methane organic compounds (NMOCs) on the biological methane (CH 4 ) oxidation process were examined. The investigation was performed on compost experiments incubated with CH 4 and selected NMOCs under different environmental conditions. The selected NMOCs had different concentrations and their effects were tested as single compounds and mixtures of compounds. The results from all experimental sets showed a decrease in CH 4 oxidation capacity of the landfill bio-cover with the increase in NMOCs concentrations. For example, in the experiment using compost with 100% moisture content at 35 deg. C without any NMOCs the V max value was 35.0 μg CH 4 h -1 g wetwt -1 . This value was reduced to 19.1 μg CH 4 h -1 g wetwt -1 when mixed NMOCs were present in the batch reactors under the same environmental conditions. The experimental oxidation rates of CH 4 in the presence of single and mixed NMOCs were modeled using the uncompetitive inhibition model and kinetic parameters, including the dissociation constants, were obtained. Additionally, the degradation rates of the NMOCs and co-metabolic abilities of methanotrophic bacteria were estimated.

Shallow Aquifer Methane Gas Source Assessment

Science.gov (United States)

Coffin, R. B.; Murgulet, D.; Rose, P. S.; Hay, R.

2014-12-01

Shale gas can contribute significantly to the world's energy demand. Hydraulic fracturing (fracking) on horizontal drill lines developed over the last 15 years makes formerly inaccessible hydrocarbons economically available. From 2000 to 2035 shale gas is predicted to rise from 1% to 46% of the total natural gas for the US. A vast energy resource is available in the United States. While there is a strong financial advantage to the application of fracking there is emerging concern about environmental impacts to groundwater and air quality from improper shale fracking operations. Elevated methane (CH4) concentrations have been observed in drinking water throughout the United States where there is active horizontal drilling. Horizontal drilling and hydraulic-fracturing can increase CH4 transport to aquifers, soil and the vadose zone. Seepage can also result from casing failure in older wells. However, there is strong evidence that elevated CH4 concentrations can be associated with topographic and hydrogeologic features, rather than shale-gas extraction processes. Carbon isotope geochemistry can be applied to study CH4source(s) in shallow vadose zone and groundwater systems. A preliminary TAMU-CC isotope data set from samples taken at different locations in southern Texas shows a wide range of CH4 signatures suggesting multiple sources of methane and carbon dioxide. These data are interpreted to distinguish regions with methane contributions from deep-sourced horizontal drilling versus shallow system microbial production. Development of a thorough environmental assessment using light isotope analysis can provide understanding of shallow anthropogenic versus natural CH4sources and assist in identifying regions that require remedial actions.

Molecular Level Investigation of CH ₄ and CO ₂ Adsorption in Hydrated Calcium–Montmorillonite

Energy Technology Data Exchange (ETDEWEB)

Lee, Mal-Soon [Physical; McGrail, B. Peter [Physical; Rousseau, Roger [Physical; Glezakou, Vassiliki-Alexandra [Physical

2017-11-17

We have studied the mechanism of intercalation and methane adsorption from a H2O/CH4/CO2 mixture on a prototypical shale component, Ca-montmorillonite. We employed ab initio molecular dynamics simulations at 323 K and 90 bar to obtain molecular level information of adsorption energetics, speciation, and structural and thermodynamic properties. Interaction of CH4 with surface Lewis acidic sites (Ca2+, surface OH) results in large induced dipoles (~1 D) that lead to relatively strong adsorption energies that level off once a full CH4 layer is formed. Intercalated CH4, also exhibits induced dipoles at low hydration levels, when the interaction with Ca2+ cations are less hindered. CO2 displaces CH4 in the coordination sphere of the cations (in the interlayer) or in the surface, thereby driving CH4 extraction. Our simulations indicate that there is a Goldilocks pressure range (~60-100 bar) where scCO2 –facilitated CH4 extraction will be maximized.

Co-digestion of solid waste: Towards a simple model to predict methane production.

Science.gov (United States)

Kouas, Mokhles; Torrijos, Michel; Schmitz, Sabine; Sousbie, Philippe; Sayadi, Sami; Harmand, Jérôme

2018-04-01

Modeling methane production is a key issue for solid waste co-digestion. Here, the effect of a step-wise increase in the organic loading rate (OLR) on reactor performance was investigated, and four new models were evaluated to predict methane yields using data acquired in batch mode. Four co-digestion experiments of mixtures of 2 solid substrates were conducted in semi-continuous mode. Experimental methane yields were always higher than the BMP values of mixtures calculated from the BMP of each substrate, highlighting the importance of endogenous production (methane produced from auto-degradation of microbial community and generated solids). The experimental methane productions under increasing OLRs corresponded well to the modeled data using the model with constant endogenous production and kinetics identified at 80% from total batch time. This model provides a simple and useful tool for technical design consultancies and plant operators to optimize the co-digestion and the choice of the OLRs. Copyright © 2018 Elsevier Ltd. All rights reserved.

Rate Coefficient for the (4)Heμ + CH4 Reaction at 500 K: Comparison between Theory and Experiment.

Science.gov (United States)

Arseneau, Donald J; Fleming, Donald G; Li, Yongle; Li, Jun; Suleimanov, Yury V; Guo, Hua

2016-03-03

The rate constant for the H atom abstraction reaction from methane by the muonic helium atom, Heμ + CH4 → HeμH + CH3, is reported at 500 K and compared with theory, providing an important test of both the potential energy surface (PES) and reaction rate theory for the prototypical polyatomic CH5 reaction system. The theory used to characterize this reaction includes both variational transition-state (CVT/μOMT) theory (VTST) and ring polymer molecular dynamics (RPMD) calculations on a recently developed PES, which are compared as well with earlier calculations on different PESs for the H, D, and Mu + CH4 reactions, the latter, in particular, providing for a variation in atomic mass by a factor of 36. Though rigorous quantum calculations have been carried out for the H + CH4 reaction, these have not yet been extended to the isotopologues of this reaction (in contrast to H3), so it is important to provide tests of less rigorous theories in comparison with kinetic isotope effects measured by experiment. In this regard, the agreement between the VTST and RPMD calculations and experiment for the rate constant of the Heμ + CH4 reaction at 500 K is excellent, within 10% in both cases, which overlaps with experimental error.

Effects of permafrost thaw on CO2 and CH4 exchange in a western Alaska peatland chronosequence

Science.gov (United States)

Carmel E. Johnston,; Stephanie A. Ewing,; Harden, Jennifer W.; Ruth K. Varner,; Wickland, Kimberly P.; Koch, Joshua C.; Fuller, Christopher C.; Manies, Kristen L.; M. Torre Jorgenson,

2014-01-01

Permafrost soils store over half of global soil carbon (C), and northern frozen peatlands store about 10% of global permafrost C. With thaw, inundation of high latitude lowland peatlands typically increases the surface-atmosphere flux of methane (CH4), a potent greenhouse gas. To examine the effects of lowland permafrost thaw over millennial timescales, we measured carbon dioxide (CO2) and CH4 exchange along sites that constitute a ~1000 yr thaw chronosequence of thermokarst collapse bogs and adjacent fen locations at Innoko Flats Wildlife Refuge in western Alaska. Peak CH4exchange in July (123 ± 71 mg CH4–C m−2 d−1) was observed in features that have been thawed for 30 to 70 (peatlands, particularly those developed on poorly drained mineral substrates, are a key locus of elevated CH4 emission to the atmosphere that must be considered for a complete understanding of high latitude CH4 dynamics.

Diffusive flux of methane from warm wetlands

Energy Technology Data Exchange (ETDEWEB)

Barber, T.R.; Burke, R.A.; Sackett, W.M. (Univ. of South Florida, St. Petersburg (USA))

1988-12-01

Diffusion of methane across the air-water interface from several wetland environments in south Florida was estimated from measured surface water concentrations using an empirically derived gas exchange model. The flux from the Everglades sawgrass marsh system varied widely, ranging from 0.18 + or{minus}0.21 mol CH{sub 4}/sq m/yr for densely vegetated regions to 2.01 + or{minus}0.88 for sparsely vegetated, calcitic mud areas. Despite brackish salinities, a strong methane flux, 1.87 + or{minus}0.63 mol CH{sub 4}/sq m/yr, was estimated for an organic-rich mangrove pond near Florida Bay. The diffusive flux accounted for 23, 36, and 13% of the total amount of CH{sub 4} emitted to the atmosphere from these environments, respectively. The average dissolved methane concentration for an organic-rich forested swamp was the highest of any site at 12.6 microM; however, the calculated diffusive flux from this location, 2.57 + or{minus}1.88 mol CH{sub 4}/sq m/yr, was diminished by an extensive plant canopy that sheltered the air-water interface from the wind. The mean diffusive flux from four freshwater lakes, 0.77 + or{minus}0.73 mol CH{sub 4}/sq m/yr, demonstrated little temperature dependence. The mean diffusive flux for an urbanized, subtropical estuary was 0.06 + or{minus}0.05 mol CH{sub 4}/sq m/yr.

China’s regional CH_4 emissions: Characteristics, interregional transfer and mitigation policies

International Nuclear Information System (INIS)

Zhang, Bo; Yang, T.R.; Chen, B.; Sun, X.D.

2016-01-01

Highlights: • China’s CH_4 emissions have significant contributions to global climate change. • The total CH_4 emissions in 2010 amount to 44.3 Tg, half from energy activities. • Half of the national total direct emissions are embodied in interregional trade. • 2/3 of the embodied emission transfers via domestic trade are energy-related. • A national comprehensive action plan to reduce CH_4 emissions should be designed. - Abstract: Methane (CH_4), the second largest greenhouse gas emitted in China, hasn’t been given enough attention in the country’s policies and actions for addressing climate change. This paper aims to perform a bottom-up estimation and multi-regional input–output analysis for China’s anthropogenic CH_4 emissions from both production-based and consumption-based insights. As the world’s largest CH_4 emitter, China’s total anthropogenic CH_4 emissions in 2010 are estimated at 44.3 Tg and correspond to 1507.9 Mt CO_2-eq by the lower global warming potential factor of 34. Energy activities as the largest contributor hold about half of the national total emissions, mainly from coal mining. Inherent economic driving factors covering consumption, investment and international exports play an important role in determining regional CH_4 emission inventories. Interregional transfers of embodied emissions via domestic trade are equivalent to half of the national total emissions from domestic production, of which two thirds are energy-related embodied emissions. Most central and western regions as net interregional CH_4 exporters such as Shanxi and Inner Mongolia have higher direct emissions, while the eastern coastal regions as net interregional importers such as Guangdong and Jiangsu always have larger embodied emissions. Since China’s CH_4 emissions have significant contributions to global climate change, a national comprehensive action plan to reduce CH_4 emissions should be designed by considering supply-side and demand

Formation and High-order Carboxylic Acids (RCOOH) in Interstellar Analogous Ices of Carbon Dioxide (CO2) and Methane(CH4)

Science.gov (United States)

Zhu, Cheng; Turner, Andrew M.; Abplanalp, Matthew J.; Kaiser, Ralf I.

2018-01-01

This laboratory study simulated the abiotic formation of carboxylic acids (RCOOH) in interstellar analogous ices of carbon dioxide (CO2) and methane (CH4) at 10 K upon exposure to energetic electrons. The chemical processing of the ices and the subsequent warm-up phase were monitored online and in situ, exploiting Fourier Transform Infrared Spectrometry and quadrupole mass spectrometry. Characteristic absorptions of functional groups of carboxylic acids (RCOOH) were observed in the infrared spectra of the irradiated ice. Two proposed reaction mechanisms replicated the kinetic profiles of the carboxylic acids along with the decay profile of the precursors during the irradiation via hydrocarbon formation, followed by carboxylation and/or through acetic acid along with mass growth processes of the alkyl chain. Mass spectra recorded during the warm-up phase demonstrated that these acids are distributed from acetic acid (CH3COOH) up to decanoic acid (C9H19COOH). High-dose irradiation studies (91 ± 14 eV) converted low-molecular-weight acids such as acetic acid (CH3COOH) and propionic acid (C2H5COOH) to higher-molecular-weight carboxylic acids, compared to low-dose irradiation studies (18 ± 3 eV). The traces of the {{{H}}}2{{C}}= {{C}}({OH}{)}2+ (m/z = 60) fragment—a link to linear carboxylic acids—implied that higher-order acids (C n H2n+1COOH, n ≥ 5) are likely branched, which correlates with the recent analysis of the structures of the monocarboxylic acids in the Murchison meteorite.

Assessing diel variation of CH4 flux from rice paddies through temperature patterns

Science.gov (United States)

Centeno, Caesar Arloo R.; Alberto, Ma Carmelita R.; Wassmann, Reiner; Sander, Bjoern Ole

2017-10-01

The diel variation in methane (CH4) flux from irrigated rice was characterized during the dry and wet cropping seasons in 2013 and 2014 using the eddy covariance (EC) technique. The EC technique has the advantage of obtaining measurements of fluxes at an extremely high temporal resolution (10Hz), meaning it records 36,000 measurements per hour. The EC measurements can very well capture the temporal variations of the diel (both diurnal and nocturnal) fluxes of CH4 and the environmental factors (temperature, surface energy flux, and gross ecosystem photosynthesis) at 30-min intervals. The information generated by this technique is important to enhance our mechanistic understanding of the different factors affecting the landscape scale diel CH4 flux. Distinct diel patterns of CH4 flux were observed when the data were partitioned into different cropping periods (pre-planting, growth, and fallow). The temporal variations of the diel CH4 flux during the dry seasons were more pronounced than during the wet seasons because the latter had so much climatic disturbance from heavy monsoon rains and occasional typhoons. Pearson correlation analysis and Granger causality test were used to confirm if the environmental factors evaluated were not only correlated with but also Granger-causing the diel CH4 flux. Soil temperature at 2.5 cm depth (Ts 2.5 cm) can be used as simple proxy for predicting diel variations of CH4 fluxes in rice paddies using simple linear regression during both the dry and wet seasons. This simple site-specific temperature response function can be used for gap-filling CH4 flux data for improving the estimates of CH4 source strength from irrigated rice production.

A Switchable Molecular Dielectric with Two Sequential Reversible Phase Transitions: [(CH3)4P]4[Mn(SCN)6].

Science.gov (United States)

Li, Qiang; Shi, Ping-Ping; Ye, Qiong; Wang, Hui-Ting; Wu, De-Hong; Ye, Heng-Yun; Fu, Da-Wei; Zhang, Yi

2015-11-16

A new organic-inorganic hybrid switchable and tunable dielectric compound, [(CH3)4P]4[Mn(SCN)6] (1), exhibits three distinct dielectric states above room temperature and undergoes two reversible solid-state phase transitions, including a structural phase transition at 330 K and a ferroelastic phase transition with the Aizu notation of mmmF2/m at 352 K. The variable-temperature structural analyses disclose that the origin of the phase transitions and dielectric anomalies can be ascribed to the reorientation or motion of both the [(CH3)4P](+) cations and [Mn(SCN)6](4-) anions in solid-state crystals.

Airborne Measurements of Atmospheric Methane Using Pulsed Laser Transmitters

Science.gov (United States)

Numata, Kenji; Riris, Haris; Wu, Stewart; Gonzalez, Brayler; Rodriguez, Michael; Hasselbrack, William; Fahey, Molly; Yu, Anthony; Stephen, Mark; Mao, Jianping;

Profiles of CH4, HDO, H2O, and N2O with improved lower tropospheric vertical resolution from Aura TES radiances

Directory of Open Access Journals (Sweden)

D. Noone

2012-02-01

Full Text Available Thermal infrared (IR radiances measured near 8 microns contain information about the vertical distribution of water vapor (H2O, the water isotopologue HDO, and methane (CH4, key gases in the water and carbon cycles. Previous versions (Version 4 or less of the TES profile retrieval algorithm used a "spectral-window" approach to minimize uncertainty from interfering species at the expense of reduced vertical resolution and sensitivity. In this manuscript we document changes to the vertical resolution and uncertainties of the TES version 5 retrieval algorithm. In this version (Version 5, joint estimates of H2O, HDO, CH4 and nitrous oxide (N2O are made using radiances from almost the entire spectral region between 1100 cm−1 and 1330 cm−1. The TES retrieval constraints are also modified in order to better use this information. The new H2O estimates show improved vertical resolution in the lower troposphere and boundary layer, while the new HDO/H2O estimates can now profile the HDO/H2O ratio between 925 hPa and 450 hPa in the tropics and during summertime at high latitudes. The new retrievals are now sensitive to methane in the free troposphere between 800 and 150 mb with peak sensitivity near 500 hPa; whereas in previous versions the sensitivity peaked at 200 hPa. However, the upper troposphere methane concentrations are biased high relative to the lower troposphere by approximately 4% on average. This bias is likely related to temperature, calibration, and/or methane spectroscopy errors. This bias can be mitigated by normalizing the CH4 estimate by the ratio of the N2O estimate relative to the N2O prior, under the assumption that the same systematic error affects both the N2O and CH4 estimates. We demonstrate that applying this ratio theoretically reduces the CH4 estimate for non-retrieved parameters that jointly affect both the N2O and CH4 estimates. The relative upper troposphere to lower troposphere bias is approximately 2.8% after this bias

Physical and biological controls over patterns of methane flux from wetland soils

Science.gov (United States)

Owens, S. M.; von Fischer, J. C.

2006-12-01

While methane (CH4) production and plant-facilitated gas transport both contribute to patterns of CH4 emissions from wetlands, the relative importance of each mechanism is uncertain. In flooded wetland soils, CH4 is produced by anaerobic methanogenic bacteria. In the absence of competing oxidizers (i.e. SO42-, NO3-, O2), CH4 production is limited by the availability of labile carbon, which is supplied from recent plant primary production (e.g. as root exudates) and converted by anaerobic fermenting bacteria into methanogenic substrate (e.g. acetate). Because diffusion of gases through saturated soils is extremely slow, the aerenchymous tissues of wetland plants provide the primary pathway for CH4 emissions in systems dominated by emergent vascular vegetation. Aerenchyma also function to shuttle atmospheric oxygen to belowground plant tissues for respiration. Consequentially, root radial oxygen loss results in an oxidized rhizosphere, which limits CH4 production and provides habitat for aerobic methanotrophic bacteria, potentially reducing CH4 emissions. To test the contribution of recent photosynthates on CH4 emissions, a shading experiment was conducted in a Juncus-dominated wetland in the Colorado Front Range. Shade treatments significantly reduced net ecosystem production (NEE) and gross primary production (GPP) compared to control plots (p=0.0194 and p=0.0551, respectively). While CH4 emissions did not significantly differ between treatments, CH4 flux rates were strongly correlated with NEE (p=0.0063) and GPP (p=0.0020), in support of the hypothesis that labile carbon from recent photosynthesis controls patterns of CH4 emissions. The relative importance of plant gas transport and methane consumption rates on CH4 emissions is not known. Methane flux is more tightly correlated with NEE than GPP, which may be explained by increased CH4 consumption or decreased CH4 production as a result of rhizospheric oxidation. The ability to predict future emissions of this

Biogas Production from Vietnamese Animal Manure, Plant Residues and Organic Waste: Influence of Biomass Composition on Methane Yield

Directory of Open Access Journals (Sweden)

T. T. T. Cu

2015-02-01

Full Text Available Anaerobic digestion is an efficient and renewable energy technology that can produce biogas from a variety of biomasses such as animal manure, food waste and plant residues. In developing countries this technology is widely used for the production of biogas using local biomasses, but there is little information about the value of these biomasses for energy production. This study was therefore carried out with the objective of estimating the biogas production potential of typical Vietnamese biomasses such as animal manure, slaughterhouse waste and plant residues, and developing a model that relates methane (CH4 production to the chemical characteristics of the biomass. The biochemical methane potential (BMP and biomass characteristics were measured. Results showed that piglet manure produced the highest CH4 yield of 443 normal litter (NL CH4 kg−1 volatile solids (VS compared to 222 from cows, 177 from sows, 172 from rabbits, 169 from goats and 153 from buffaloes. Methane production from duckweed (Spirodela polyrrhiza was higher than from lawn grass and water spinach at 340, 220, and 110.6 NL CH4 kg−1 VS, respectively. The BMP experiment also demonstrated that the CH4 production was inhibited with chicken manure, slaughterhouse waste, cassava residue and shoe-making waste. Statistical analysis showed that lipid and lignin are the most significant predictors of BMP. The model was developed from knowledge that the BMP was related to biomass content of lipid, lignin and protein from manure and plant residues as a percentage of VS with coefficient of determination (R-square at 0.95. This model was applied to calculate the CH4 yield for a household with 17 fattening pigs in the highlands and lowlands of northern Vietnam.

Biogas production from vietnamese animal manure, plant residues and organic waste: influence of biomass composition on methane yield.

Science.gov (United States)

Cu, T T T; Nguyen, T X; Triolo, J M; Pedersen, L; Le, V D; Le, P D; Sommer, S G

2015-02-01

Anaerobic digestion is an efficient and renewable energy technology that can produce biogas from a variety of biomasses such as animal manure, food waste and plant residues. In developing countries this technology is widely used for the production of biogas using local biomasses, but there is little information about the value of these biomasses for energy production. This study was therefore carried out with the objective of estimating the biogas production potential of typical Vietnamese biomasses such as animal manure, slaughterhouse waste and plant residues, and developing a model that relates methane (CH4) production to the chemical characteristics of the biomass. The biochemical methane potential (BMP) and biomass characteristics were measured. Results showed that piglet manure produced the highest CH4 yield of 443 normal litter (NL) CH4 kg(-1) volatile solids (VS) compared to 222 from cows, 177 from sows, 172 from rabbits, 169 from goats and 153 from buffaloes. Methane production from duckweed (Spirodela polyrrhiza) was higher than from lawn grass and water spinach at 340, 220, and 110.6 NL CH4 kg(-1) VS, respectively. The BMP experiment also demonstrated that the CH4 production was inhibited with chicken manure, slaughterhouse waste, cassava residue and shoe-making waste. Statistical analysis showed that lipid and lignin are the most significant predictors of BMP. The model was developed from knowledge that the BMP was related to biomass content of lipid, lignin and protein from manure and plant residues as a percentage of VS with coefficient of determination (R-square) at 0.95. This model was applied to calculate the CH4 yield for a household with 17 fattening pigs in the highlands and lowlands of northern Vietnam.

Recombination of radiation defects in solid methane: neutron sources and cryo-volcanism on celestial bodies

Science.gov (United States)

Kirichek, O.; Savchenko, E. V.; Lawson, C. R.; Khyzhniy, I. V.; Jenkins, D. M.; Uyutnov, S. A.; Bludov, M. A.; Haynes, D. J.

2018-03-01

Physicochemical properties of solid methane exposed to ionizing radiation have attracted significant interest in recent years. Here we present new trends in the study of radiation effects in solid methane. We particularly focus on relaxation phenomena in solid methane pre-irradiated by energetic neutrons and electron beam. We compare experimental results obtained in the temperature range from 10K to 100K with a model based on the assumption that radiolysis defect recombinations happen in two stages, at two different temperatures. In the case of slow heating up of the solid methane sample, irradiated at 10K, the first wave of recombination occurs around 20K with a further second wave taking place between 50 and 60K. We also discuss the role of the recombination mechanisms in “burp” phenomenon discovered by J. Carpenter in the late 1980s. An understanding of these mechanisms is vital for the designing and operation of solid methane moderators used in advanced neutron sources and could also be a possible explanation for the driving forces behind cryo-volcanism on celestial bodies.

Detection of Abiotic Methane in Terrestrial Continental Hydrothermal Systems: Implications for Methane on Mars

Science.gov (United States)

Socki, Richard A.; Niles, Paul B.; Gibson, Everett K., Jr.; Romanek, Christopher S.; Zhang, Chuanlun L.; Bissada, Kadry K.

2008-01-01

The recent detection of methane in the Martian atmosphere and the possibility that its origin could be attributed to biological activity, have highlighted the importance of understanding the mechanisms of methane formation and its usefulness as a biomarker. Much debate has centered on the source of the methane in hydrothermal fluids, whether it is formed biologically by microorganisms, diagenetically through the decomposition of sedimentary organic matter, or inorganically via reduction of CO2 at high temperatures. Ongoing research has now shown that much of the methane present in sea-floor hydrothermal systems is probably formed through inorganic CO2 reduction processes at very high temperatures (greater than 400 C). Experimental results have indicated that methane might form inorganically at temperatures lower still, however these results remain controversial. Currently, methane in continental hydrothermal systems is thought to be formed mainly through the breakdown of sedimentary organic matter and carbon isotope equilibrium between CO2 and CH4 is thought to be rarely present if at all. Based on isotopic measurements of CO2 and CH4 in two continental hydrothermal systems, we suggest that carbon isotope equilibration exists at temperatures as low as 155 C. This would indicate that methane is forming through abiotic CO2 reduction at lower temperatures than previously thought and could bolster arguments for an abiotic origin of the methane detected in the martian atmosphere.

Increased importance of methane reduction for a 1.5 degree target

Science.gov (United States)

Collins, William J.; Webber, Christopher P.; Cox, Peter M.; Huntingford, Chris; Lowe, Jason; Sitch, Stephen; Chadburn, Sarah E.; Comyn-Platt, Edward; Harper, Anna B.; Hayman, Garry; Powell, Tom

2018-04-01

To understand the importance of methane on the levels of carbon emission reductions required to achieve temperature goals, a processed-based approach is necessary rather than reliance on the transient climate response to emissions. We show that plausible levels of methane (CH4) mitigation can make a substantial difference to the feasibility of achieving the Paris climate targets through increasing the allowable carbon emissions. This benefit is enhanced by the indirect effects of CH4 on ozone (O3). Here the differing effects of CH4 and CO2 on land carbon storage, including the effects of surface O3, lead to an additional increase in the allowable carbon emissions with CH4 mitigation. We find a simple robust relationship between the change in the 2100 CH4 concentration and the extra allowable cumulative carbon emissions between now and 2100 (0.27 ± 0.05 GtC per ppb CH4). This relationship is independent of modelled climate sensitivity and precise temperature target, although later mitigation of CH4 reduces its value and thus methane reduction effectiveness. Up to 12% of this increase in allowable emissions is due to the effect of surface ozone. We conclude early mitigation of CH4 emissions would significantly increase the feasibility of stabilising global warming below 1.5 °C, alongside having co-benefits for human and ecosystem health.

Evaluating Bay Area Methane Emission Inventory

Energy Technology Data Exchange (ETDEWEB)

Fischer, Marc [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Jeong, Seongeun [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

2016-03-01

As a regulatory agency, evaluating and improving estimates of methane (CH4) emissions from the San Francisco Bay Area is an area of interest to the Bay Area Air Quality Management District (BAAQMD). Currently, regional, state, and federal agencies generally estimate methane emissions using bottom-up inventory methods that rely on a combination of activity data, emission factors, biogeochemical models and other information. Recent atmospheric top-down measurement estimates of methane emissions for the US as a whole (e.g., Miller et al., 2013) and in California (e.g., Jeong et al., 2013; Peischl et al., 2013) have shown inventories underestimate total methane emissions by ~ 50% in many areas of California, including the SF Bay Area (Fairley and Fischer, 2015). The goal of this research is to provide information to help improve methane emission estimates for the San Francisco Bay Area. The research effort builds upon our previous work that produced methane emission maps for each of the major source sectors as part of the California Greenhouse Gas Emissions Measurement (CALGEM) project (http://calgem.lbl.gov/prior_emission.html; Jeong et al., 2012; Jeong et al., 2013; Jeong et al., 2014). Working with BAAQMD, we evaluate the existing inventory in light of recently published literature and revise the CALGEM CH4 emission maps to provide better specificity for BAAQMD. We also suggest further research that will improve emission estimates. To accomplish the goals, we reviewed the current BAAQMD inventory, and compared its method with those from the state inventory from the California Air Resources Board (CARB), the CALGEM inventory, and recent published literature. We also updated activity data (e.g., livestock statistics) to reflect recent changes and to better represent spatial information. Then, we produced spatially explicit CH4 emission estimates on the 1-km modeling grid used by BAAQMD. We present the detailed activity data, methods and derived emission maps by sector

BOREAS TGB-1/TGB-3 CH4 Chamber Flux Data over the NSA Fen

Science.gov (United States)

Bubier, Jill L.; Moore, Tim R.; Hall, Forrest G. (Editor); Conrad, Sara K. (Editor)

2000-01-01

The BOREAS TGB-3 team collected methane (CH4) chamber flux measurements at the NSA fen site during May-September 1994 and June-October 1996. Gas samples were extracted approximately every 7 days from chambers and analyzed at the NSA lab facility. The data are provided in tabular ASCII files.

Kinetics of the Formation and Dissociation of Gas Hydrates from CO₂-CH₄ Mixtures

Directory of Open Access Journals (Sweden)

Devinder Mahajan

2012-07-01

Full Text Available Sequestration of carbon dioxide (CO₂ in the form of its hydrates in natural methane (CH₄ hydrate reservoirs, via CO₂/CH₄ exchange, is an attractive pathway that also yields valuable CH₄ gas as product. In this paper, we describe a macroscale experiment to form CO₂ and CH₄-CO₂ hydrates, under seafloor-mimic conditions, in a vessel fitted with glass windows that provides visualization of hydrates throughout formation and dissociation processes. Time resolved pressure and temperature data as well as images of hydrates are presented. Quantitative gas conversions with pure CO₂, calculated from gas chromatographic measurements yielded values that range from 23 – 59% that correspond to the extent of formed hydrates. In CH₄-rich CH₄-CO₂ mixed gas systems, CH₄ hydrates were found to form preferentially.

Reduced biomass burning emissions reconcile conflicting estimates of the post-2006 atmospheric methane budget.

Science.gov (United States)

Worden, John R; Bloom, A Anthony; Pandey, Sudhanshu; Jiang, Zhe; Worden, Helen M; Walker, Thomas W; Houweling, Sander; Röckmann, Thomas

2017-12-20

Several viable but conflicting explanations have been proposed to explain the recent ~8 p.p.b. per year increase in atmospheric methane after 2006, equivalent to net emissions increase of ~25 Tg CH 4 per year. A concurrent increase in atmospheric ethane implicates a fossil source; a concurrent decrease in the heavy isotope content of methane points toward a biogenic source, while other studies propose a decrease in the chemical sink (OH). Here we show that biomass burning emissions of methane decreased by 3.7 (±1.4) Tg CH 4 per year from the 2001-2007 to the 2008-2014 time periods using satellite measurements of CO and CH 4 , nearly twice the decrease expected from prior estimates. After updating both the total and isotopic budgets for atmospheric methane with these revised biomass burning emissions (and assuming no change to the chemical sink), we find that fossil fuels contribute between 12-19 Tg CH 4 per year to the recent atmospheric methane increase, thus reconciling the isotopic- and ethane-based results.

Hybrid perovskite resulting from the solid-state reaction between the organic cations and perovskite layers of alpha1-(Br-(CH(2))(2)-NH(3))(2)PbI(4).

Science.gov (United States)

Sourisseau, Sebastien; Louvain, Nicolas; Bi, Wenhua; Mercier, Nicolas; Rondeau, David; Buzaré, Jean-Yves; Legein, Christophe

2007-07-23

The alpha1-(Br-(CH(2))(2)-NH(3))(2)PbI(4) hybrid perovskite undergoes a solid-state transformation, that is, the reaction between the organic cations and the perovskite layers to give the new hybrid perovskite (Br-(CH(2))(2)-NH(3))(2-x)(I-(CH(2))(2)-NH(3))(x)PbBr(x)I(4-x), based on mixed halide inorganic layers. This transformation has been followed by a conventional powder X-ray diffraction system equipped with a super speed detector, and both solid-state (13)C NMR and ESI/MS measurements have been adopted in the estimation of the rate of halide substitution. The first reaction step leads to the special composition of x approximately 1 (A phase), while the complete substitution is not achieved even at elevated temperature (x(max) approximately 1.85 (B phase)). This unprecedented solid-state reaction between organic and inorganic components of a hybrid perovskite can be considered as a completely new strategy to achieve interesting hybrid perovskites.

Reticular synthesis of HKUST-like tbo MOFs with enhanced CH4 storage

KAUST Repository

Spanopoulos, Ioannis

2015-12-22

Successful implementation of reticular chemistry using a judiciously designed rigid octatopic carboxylate organic linker allowed the construction of expanded HKUST-1-like tbo-MOF series with intrinsic strong CH4 adsorption sites. The Cu-analogue displayed a concomitant enhancement of the gravimetric and volumetric surface area with the highest reported CH4 uptake among the tbo family, comparable to the best performing MOFs for CH4 storage. The corresponding gravimetric (BET) and volumetric surface area of 3971 m2 g-1 and 2363 m2 cm-3 represent an increase of respectively 115 % and 47 % in comparison to the corresponding values for the prototypical HKUST-1 (tbo-MOF-1), and 42 % and 20 % higher than tbo-MOF-2. High pressure methane adsorption isotherms revealed a high total gravimetric and volumetric CH4 uptakes, reaching 372 cm3 (STP) g-1 and 221 cm3 (STP) cm-3 respectively at 85 bar and 298 K. The corresponding working capacities between 5-80 bar were found to be 294 cm3 (STP) g-1 and 175 cm3 (STP) cm-3 and are placed among the best performing MOFs for CH4 storage particularly at relatively low temperature (e.g. 326 cm3 (STP) g-1 and 194 cm3 (STP) cm-3 at 258 K). To better understand the structure-property relationship and gain insight on the mechanism accounting for the resultant enhanced CH4 storage capacity, molecular simulation study was performed and revealed the presence of very strong CH4 adsorption sites at the vicinity of the organic linker with similar adsorption energetics as the open metal sites. The present findings supports the potential of tbo-MOFs based on the supermolecular building layer (SBL) approach as an ideal platform to further enhance the CH4 storage capacity via expansion and functionalization of the quadrangular pillars.

Reticular synthesis of HKUST-like tbo MOFs with enhanced CH4 storage

KAUST Repository

Spanopoulos, Ioannis; Tsangarakis, Constantinos; Klontzas, Emmanuel; Tylianakis, Emmanuel; Froudakis, George; Adil, Karim; Belmabkhout, Youssef; Eddaoudi, Mohamed; Trikalitis, Pantelis N.

2015-01-01

Successful implementation of reticular chemistry using a judiciously designed rigid octatopic carboxylate organic linker allowed the construction of expanded HKUST-1-like tbo-MOF series with intrinsic strong CH4 adsorption sites. The Cu-analogue displayed a concomitant enhancement of the gravimetric and volumetric surface area with the highest reported CH4 uptake among the tbo family, comparable to the best performing MOFs for CH4 storage. The corresponding gravimetric (BET) and volumetric surface area of 3971 m2 g-1 and 2363 m2 cm-3 represent an increase of respectively 115 % and 47 % in comparison to the corresponding values for the prototypical HKUST-1 (tbo-MOF-1), and 42 % and 20 % higher than tbo-MOF-2. High pressure methane adsorption isotherms revealed a high total gravimetric and volumetric CH4 uptakes, reaching 372 cm3 (STP) g-1 and 221 cm3 (STP) cm-3 respectively at 85 bar and 298 K. The corresponding working capacities between 5-80 bar were found to be 294 cm3 (STP) g-1 and 175 cm3 (STP) cm-3 and are placed among the best performing MOFs for CH4 storage particularly at relatively low temperature (e.g. 326 cm3 (STP) g-1 and 194 cm3 (STP) cm-3 at 258 K). To better understand the structure-property relationship and gain insight on the mechanism accounting for the resultant enhanced CH4 storage capacity, molecular simulation study was performed and revealed the presence of very strong CH4 adsorption sites at the vicinity of the organic linker with similar adsorption energetics as the open metal sites. The present findings supports the potential of tbo-MOFs based on the supermolecular building layer (SBL) approach as an ideal platform to further enhance the CH4 storage capacity via expansion and functionalization of the quadrangular pillars.

The global warming potential of methane reassessed with combined stratosphere and troposphere chemistry

Science.gov (United States)

Holmes, C. D.; Archibald, A. T.; Eastham, S. D.; Søvde, O. A.

2017-12-01

Methane is a direct and indirect greenhouse gas. The direct greenhouse effect comes from the radiation absorbed and emitted by methane itself. The indirect greenhouse effect comes from radiatively active gases that are produced during methane oxidation: principally O3, H2O, and CO2. Methane also suppresses tropospheric OH, which indirectly affects numerous greenhouses gases and aerosols. Traditionally, the methane global warming potential (GWP) has included the indirect effects on tropospheric O3 and OH and stratospheric H2O, with these effects estimated independently from unrelated tropospheric and stratospheric chemistry models and observations. Using this approach the CH4 is about 28 over 100 yr (without carbon cycle feedbacks, IPCC, 2013). Here we present a comprehensive analysis of the CH4 GWP in several 3-D global atmospheric models capable of simulating both tropospheric and stratospheric chemistry (GEOS-Chem, Oslo CTM3, UKCA). This enables us to include, for the first time, the indirect effects of CH4 on stratospheric O3 and stratosphere-troposphere coupling. We diagnose the GWP from paired simulations with and without a 5% perturbation to tropospheric CH4 concentrations. Including stratospheric chemistry nearly doubles the O3 contribution to CH4 GWP because of O3 production in the lower stratosphere and because CH4 inhibits Cl-catalyzed O3 loss in the upper stratosphere. In addition, stratosphere-troposphere coupling strengthens the chemical feedback on its own lifetime. In the stratosphere, this feedback operates by a CH4 perturbation thickening the stratospheric O3 layer, which impedes UV-driven OH production in the troposphere and prolongs the CH4 lifetime. We also quantify the impact of CH4-derived H2O on the stratospheric HOx cycles but these effects are small. Combining all of the above, these models suggest that the 100-yr GWP of CH4 is over 33.5, a 20% increase over the latest IPCC assessment.

A biomimetic methane-oxidising catalyst

Energy Technology Data Exchange (ETDEWEB)

Dalton, H [Warwick Univ., Coventry (United Kingdom). Dept. of Biological Sciences

1997-12-31

The diminishing resources of petroleum oil has meant that there has been considerable efforts in recent years to find a suitable substitute for gasoline as a transportation fuel. Methanol has been identified as a suitable substitute since it is a readily combustible fuel which can be manufactured from a number of different sources. Methane is commonly used as a starting material for the production of synthesis gas (CO + H{sub 2}) and hence methanol. It is well known that the cleavage of the C-H bond of methane is extremely difficult (bond energy is around 104 kcal/mol) and that fairly drastic conditions are required to convert methane into methanol. Temperatures around 1200 deg C and pressures of up to 100 atmospheres over metal catalysts in a series of reactions are required to effect this process. Efforts have been made to reduce the temperature and the number of steps by using lanthanide ruthenium oxide catalyst but such reactions are still thermodynamically endothermic. An energetically more efficient reaction would be the direct conversion of methane to methanol using oxygen as the oxidant: CH{sub 4} + 1/2O{sub 2} -> CH{sub 3}OH {Delta}H deg = - 30.7 kcal/mol. Such a direct oxidation route is manifest in the bacterially-mediated oxidation of methane by methanotrophic bacteria. These organisms effect the direct oxidation of methane to methanol by the enzyme methane monooxygenase (MMO) as part of the reaction sequences to oxidize methane to carbon dioxide. (14 refs.)

A biomimetic methane-oxidising catalyst

Energy Technology Data Exchange (ETDEWEB)

Dalton, H. [Warwick Univ., Coventry (United Kingdom). Dept. of Biological Sciences

1996-12-31

The diminishing resources of petroleum oil has meant that there has been considerable efforts in recent years to find a suitable substitute for gasoline as a transportation fuel. Methanol has been identified as a suitable substitute since it is a readily combustible fuel which can be manufactured from a number of different sources. Methane is commonly used as a starting material for the production of synthesis gas (CO + H{sub 2}) and hence methanol. It is well known that the cleavage of the C-H bond of methane is extremely difficult (bond energy is around 104 kcal/mol) and that fairly drastic conditions are required to convert methane into methanol. Temperatures around 1200 deg C and pressures of up to 100 atmospheres over metal catalysts in a series of reactions are required to effect this process. Efforts have been made to reduce the temperature and the number of steps by using lanthanide ruthenium oxide catalyst but such reactions are still thermodynamically endothermic. An energetically more efficient reaction would be the direct conversion of methane to methanol using oxygen as the oxidant: CH{sub 4} + 1/2O{sub 2} -> CH{sub 3}OH {Delta}H deg = - 30.7 kcal/mol. Such a direct oxidation route is manifest in the bacterially-mediated oxidation of methane by methanotrophic bacteria. These organisms effect the direct oxidation of methane to methanol by the enzyme methane monooxygenase (MMO) as part of the reaction sequences to oxidize methane to carbon dioxide. (14 refs.)

Method for indirect quantification of CH4 production via H2O production using hydrogenotrophic methanogens

Directory of Open Access Journals (Sweden)

Ruth-Sophie eTaubner

2016-04-01

Full Text Available ydrogenotrophic methanogens are an intriguing group of microorganisms from the domain Archaea. They exhibit extraordinary ecological, biochemical, physiological characteristics colorbox{yellow}{and have a huge biotechnological potential}. Yet, the only possibility to assess the methane (CH$_4$ production potential of hydrogenotrophic methanogens is to apply gas chromatographic quantification of CH$_4$.In order to be able to effectively screen pure cultures of hydrogenotrophic methanogens regarding their CH$_4$ production potential we developed a novel method for indirect quantification of colorbox{yellow}{the} volumetric CH$_4$ production rate by measuring colorbox{yellow}{the} volumetric water production rate. This colorbox{yellow}{ } method was established in serum bottles for cultivation of methanogens in closed batch cultivation mode. Water production was colorbox{yellow}{estimated} by determining the difference in mass increase in an isobaric setting.This novel CH$_4$ quantification method is an accurate and precise analytical technique, colorbox{yellow}{which can be used} to rapidly screen pure cultures of methanogens regarding colorbox{yellow}{their} volumetric CH$_{4}$ evolution rate. colorbox{yellow}{It} is a cost effective alternative colorbox{yellow}{determining} CH$_4$ production of methanogens over CH$_4$ quantification by using gas chromatography, especially if colorbox{yellow}{ } applied as a high throughput quantification method. colorbox{yellow}{Eventually, the} method can be universally applied for quantification of CH$_4$ production from psychrophilic, thermophilic and hyperthermophilic hydrogenotrophic methanogens.

Methane oxidation in an intensively cropped tropical rice field soil under long-term application of organic and mineral fertilizers.

Science.gov (United States)

Nayak, D R; Babu, Y Jagadeesh; Datta, A; Adhya, T K

2007-01-01

Methane (CH4) oxidation is the only known biological sink process for mitigating atmospheric and terrestrial emissions of CH4, a major greenhouse gas. Methane oxidation in an alluvial soil planted to rice (Oryza sativa L.) under long-term application of organic (compost with a C/N ratio of 21.71), and mineral fertilizers was measured in a field-cum-laboratory incubation study. Oxidation rates were quantified in terms of decrease in the concentration of CH4 in the headspace of incubation vessels and expressed as half-life (t(1)2) values. Methane oxidation rates significantly differed among the treatments and growth stages of the rice crop. Methane oxidation rates were high at the maximum tillering and maturity stages, whereas they were low at grain-filling stage. Methane oxidation was low (t(1)2) = 15.76 d) when provided with low concentration of CH4. On the contrary, high concentration of CH4 resulted in faster oxidation (t(1)2) = 6.67 d), suggesting the predominance of "low affinity oxidation" in rice fields. Methane oxidation was stimulated following the application of mineral fertilizers or compost implicating nutrient limitation as one of the factors affecting the process. Combined application of compost and mineral fertilizer, however, inhibited CH4 oxidation probably due to N immobilization by the added compost. The positive effect of mineral fertilizer on CH4 oxidation rate was evident only at high CH4 concentration (t(1)2 = 4.80 d), while at low CH4 concentration their was considerable suppression (t(1) = 17.60 d). Further research may reveal that long-term application of fertilizers, organic or inorganic, may not inhibit CH4 oxidation.

Methane feedbacks to the global climate system in a warmer world

NARCIS (Netherlands)

Dean, Joshua F.; Middelburg, Jack J.; Röckmann, Thomas; Aerts, Rien; Blauw, Luke G.; Egger, Matthias; Jetten, Mike S.M.; de Jong, Anniek E.E.; Meisel, Ove H.; Rasigraf, Olivia; Slomp, Caroline P.; in't Zandt, Michiel H.; Dolman, A. J.

Methane (CH4) is produced in many natural systems that are vulnerable to change under a warming climate, yet current CH4 budgets, as well as future shifts in CH4 emissions, have high uncertainties. Climate change has the potential to increase CH4 emissions from critical systems such as wetlands,

Methane emission from wetland rice fields

NARCIS (Netherlands)

Denier van der Gon, H.A.C.

1996-01-01

Methane (CH ₄ ) is an important greenhouse gas and plays a key role in tropospheric and stratospheric chemistry. Wetland rice fields are an important source of methane, accounting for approximately 20% of the global anthropogenic

CH4 emissions from enteric fermentation in Austria

International Nuclear Information System (INIS)

Gebetsroither, E.; Orthofer, R.; Strebl, F.

2002-07-01

This report contains the results of an inventory for methane (CH 4 ) emissions from agricultural enteric fermentation in Austria for the period 1980-2001. Emissions were calculated according to IPCC guidelines. The detailed IPCC 'Tier 2' methodology was applied for cattle (which contribute the vast majority of emissions). The 'Tier 2' methodology relies on specific emission factors that are calculated from the energy intake for different cattle farming practices. The less detailed 'Tier 1' methodology was applied for all other animal categories. Emissions from organic and conventional farming practices were calculated separately. Results indicate that CH 4 emissions from manure management have increased from 1980 to a peak in 1984-1985, and since then have steadily declined. CH 4 emissions were about 169.300 t/yr in 'Kyoto' base year 1990 and have since declined by about 11 % to about 150.000 t/yr in 2001. Almost all emissions (95 % in 1990 and 94 % in 2001) are caused by cattle farming. The contribution of 'dairy cattle' to all emissions from cattle was 49 % in 1990, and has declined to 43 % in 2001. The overall reduction was caused mainly by a decrease in the total numbers of animals. However, in the case of dairy cows the reduction of animals is partly counterbalanced by an increase in emissions per animal (because of the increasing gross energy intake and milk production of milk cattle since 1990). Uncertainties of emissions were estimated with a 'Monte Carlo' simulation. Assuming a normal probability distribution, the calculated standard deviation is 4 %. This indicates there is a 95 % probability that CH 4 emissions are between ± 2 standard deviations, i.e. between 153.000 t and 178.000 t in the year 1990 and between 138.000 t and 162.000 t in the year 2001. (author)

Methane bubbling from northern lakes: present and future contributions to the global methane budget.

Science.gov (United States)

Walter, Katey M; Smith, Laurence C; Chapin, F Stuart

2007-07-15

Large uncertainties in the budget of atmospheric methane (CH4) limit the accuracy of climate change projections. Here we describe and quantify an important source of CH4 -- point-source ebullition (bubbling) from northern lakes -- that has not been incorporated in previous regional or global methane budgets. Employing a method recently introduced to measure ebullition more accurately by taking into account its spatial patchiness in lakes, we estimate point-source ebullition for 16 lakes in Alaska and Siberia that represent several common northern lake types: glacial, alluvial floodplain, peatland and thermokarst (thaw) lakes. Extrapolation of measured fluxes from these 16 sites to all lakes north of 45 degrees N using circumpolar databases of lake and permafrost distributions suggests that northern lakes are a globally significant source of atmospheric CH4, emitting approximately 24.2+/-10.5Tg CH4yr(-1). Thermokarst lakes have particularly high emissions because they release CH4 produced from organic matter previously sequestered in permafrost. A carbon mass balance calculation of CH4 release from thermokarst lakes on the Siberian yedoma ice complex suggests that these lakes alone would emit as much as approximately 49000Tg CH4 if this ice complex was to thaw completely. Using a space-for-time substitution based on the current lake distributions in permafrost-dominated and permafrost-free terrains, we estimate that lake emissions would be reduced by approximately 12% in a more probable transitional permafrost scenario and by approximately 53% in a 'permafrost-free' Northern Hemisphere. Long-term decline in CH4 ebullition from lakes due to lake area loss and permafrost thaw would occur only after the large release of CH4 associated thermokarst lake development in the zone of continuous permafrost.

Year-round methane emissions from permafrost in a North-east Siberian region

Science.gov (United States)

Castro-Morales, Karel; Kaiser, Sonja; Kleinen, Thomas; Kwon, Min Jung; Kittler, Fanny; Zaehle, Sönke; Beer, Christian; Göckede, Mathias

2017-04-01

In recent decades, permafrost regions in northern latitudes are thawing as a response of climate warming. Soils in permafrost areas contain vast amounts of organic material that is released into the environment after thaw, providing new labile material for bacterial decomposition. As a result, higher production of methane in the anoxic soil layers and within anaerobic wetlands is anticipated, and this will be further released to the atmosphere. In order to assess the current large-scale methane emissions from a wetland permafrost-thaw affected area, we present results of year-round simulated methane emissions at regional scale for a section at the Russian far Northeast in Siberia, located in the low Arctic tundra and characterized by continuous permafrost. For this we use a newly developed process-based methane model built in the framework of the land surface model JSBACH. The model contains explicit permafrost processes and an improved representation of the horizontal extent of wetlands with a hydrological model (TOPMODEL). Model simulated distribution and horizontal extent of wetlands is evaluated against high-resolution remote sensing data. Total and individual regional methane emissions by ebullition, molecular diffusion, plant-mediated and emissions through snow are presented for 2014 and 2015. The model shows a reasonable seasonal transition between the individual methane emission paths. Most of the methane emissions to the atmosphere occur in summer (July, August, September), with the peak of the emissions during August. In this month, plant-mediated transport is the dominant emission path with about 15 mg CH4 m-2 d-1 in 2014, followed by ebullition (7 mg CH4 m-2 d-1) accounting for about half of the emissions thorough plants. Molecular diffusion is a minor contributor with only 0.006 mg CH4 m-2 d-1 at the peak of the summer emissions. Methane emissions through snow occur only during spring, fall and winter months, with higher emissions in spring and autumn

BOREAS TGB-1 NSA CH4 and CO2 Chamber Flux Data

Science.gov (United States)

Hall, Forrest G. (Editor); Conrad, Sara K. (Editor); Crill, Patrick; Varner, Ruth K.

2000-01-01

The BOREAS TGB-1 team made methane (CH4) and carbon dioxide (CO2) dark chamber flux measurements at the NSA-OJP, NSA-OBS, NSA-BP, and NSA-YJP sites from 16-May-1994 through 13-Sep-1994. Gas samples were extracted approximately every 7 days from dark chambers and analyzed at the NSA lab facility. The data are provided in tabular ASCII files.

Photodissociation thresholds of OH produced from CH sub 3 OH in solid neon and argon

CERN Document Server

Cheng, B M; Lo, W J; Lee, Y P

2001-01-01

Photodissociation thresholds of OH from CH sub 3 OH in solid Ne and Ar were determined via photolysis of CH sub 3 OH/Ne and CH sub 3 OH/Ar (1/200) samples in situ at 4 K. The samples were irradiated with VUV synchrotron radiation after dispersion by a Seya-Namioka monochromator. The OH photo-product was detected by means of laser-induced fluorescence technique. The increase of fluorescent intensity of OH was monitored and recorded after the matrix sample was irradiated at different wavelengths for 3-5 min. Photodissociation threshold energies of 7.13+-0.02 eV (174.0+-0.5 nm) and 7.08+-0.04 eV (175.0+-1.0 nm) were measured for OH production of CH sub 3 OH in solid Ne and Ar, respectively.

Optical properties of bias-induced CH sub 4 -H sub 2 plasma for diamond film deposition

CERN Document Server

Zhu, X D; Zhou, H Y; Wen, X H; Li, D

2002-01-01

Methane (CH sub 4) and hydrogen (H sub 2) reactive gas mixture has been in situ investigated in a hot filament diamond chemical vapor deposition reactor with a negatively variable biasing voltage applied to the hot filament with respect to the substrate using infrared absorption spectroscopy and optical emission spectroscopy. It is found that CH sub 4 converts increasingly to C sub 2 H sub 2 upon raising the filament temperature in a pure thermal activation state, no optical emission of species is observed. Upon bias application, both CH sub 4 and C sub 2 H sub 2 in infrared (IR) absorption intensity decrease with increasing bias current, even the IR absorption intensity of C sub 2 H sub 2 decreases more rapidly than that of CH sub 4. Meanwhile, the clear emission lines indexed to H, CH, and CH sup + appear in the optical emission spectrum obtained, showing that a large amount of excited radicals are produced in the gas phase after applying bias. It is believed that the further generation of activated radical...

Fluxes of CH4 and N2O in aspen stands grown under ambient and twice-ambient CO2

DEFF Research Database (Denmark)

Ambus, P.; Robertson, G.P.

1999-01-01

Elevated atmospheric CO2 has the potential to change below-ground nutrient cycling and thereby alter the soil-atmosphere exchange of biogenic trace gases. We measured fluxes of CH4 and N2O in trembling aspen (Populus tremuloides Michx.) stands grown in open-top chambers under ambient and twice......-ambient CO2 concentrations crossed with `high' and low soil-N conditions. Flux measurements with small static chambers indicated net CH4 oxidation in the open-top chambers. Across dates, CH4 oxidation activity was significantly (P CO2 (8.7 mu g CH4-C m(-2) h(-1)) than...... with elevated CO2 (6.5 mu g CH4-C m(-2) h(-1)) in the low N soil. Likewise, across dates and soil N treatments CH4 was oxidized more rapidly (P CO2 (9.5 mu g CH4-C m(-2) h(-1)) than in chambers with elevated CO2 (8.8 mu g CH4-C m(-2) h(-1)). Methane oxidation in soils incubated...

Large methane releases lead to strong aerosol forcing and reduced cloudiness

Directory of Open Access Journals (Sweden)

T. Kurtén

2011-07-01

Full Text Available The release of vast quantities of methane into the atmosphere as a result of clathrate destabilization is a potential mechanism for rapid amplification of global warming. Previous studies have calculated the enhanced warming based mainly on the radiative effect of the methane itself, with smaller contributions from the associated carbon dioxide or ozone increases. Here, we study the effect of strongly elevated methane (CH₄ levels on oxidant and aerosol particle concentrations using a combination of chemistry-transport and general circulation models. A 10-fold increase in methane concentrations is predicted to significantly decrease hydroxyl radical (OH concentrations, while moderately increasing ozone (O₃. These changes lead to a 70 % increase in the atmospheric lifetime of methane, and an 18 % decrease in global mean cloud droplet number concentrations (CDNC. The CDNC change causes a radiative forcing that is comparable in magnitude to the longwave radiative forcing ("enhanced greenhouse effect" of the added methane. Together, the indirect CH₄-O₃ and CH₄-OH-aerosol forcings could more than double the warming effect of large methane increases. Our findings may help explain the anomalously large temperature changes associated with historic methane releases.

Electronic Effects on Room-Temperature, Gas-Phase C-H Bond Activations by Cluster Oxides and Metal Carbides: The Methane Challenge.

Science.gov (United States)

Schwarz, Helmut; Shaik, Sason; Li, Jilai

2017-12-06

This Perspective discusses a story of one molecule (methane), a few metal-oxide cationic clusters (MOCCs), dopants, metal-carbide cations, oriented-electric fields (OEFs), and a dizzying mechanistic landscape of methane activation! One mechanism is hydrogen atom transfer (HAT), which occurs whenever the MOCC possesses a localized oxyl radical (M-O • ). Whenever the radical is delocalized, e.g., in [MgO] n •+ the HAT barrier increases due to the penalty of radical localization. Adding a dopant (Ga 2 O 3 ) to [MgO] 2 •+ localizes the radical and HAT transpires. Whenever the radical is located on the metal centers as in [Al 2 O 2 ] •+ the mechanism crosses over to proton-coupled electron transfer (PCET), wherein the positive Al center acts as a Lewis acid that coordinates the methane molecule, while one of the bridging oxygen atoms abstracts a proton, and the negatively charged CH 3 moiety relocates to the metal fragment. We provide a diagnostic plot of barriers vs reactants' distortion energies, which allows the chemist to distinguish HAT from PCET. Thus, doping of [MgO] 2 •+ by Al 2 O 3 enables HAT and PCET to compete. Similarly, [ZnO] •+ activates methane by PCET generating many products. Adding a CH 3 CN ligand to form [(CH 3 CN)ZnO] •+ leads to a single HAT product. The CH 3 CN dipole acts as an OEF that switches off PCET. [MC] + cations (M = Au, Cu) act by different mechanisms, dictated by the M + -C bond covalence. For example, Cu + , which bonds the carbon atom mostly electrostatically, performs coupling of C to methane to yield ethylene, in a single almost barrier-free step, with an unprecedented atomic choreography catalyzed by the OEF of Cu + .

Anaerobic co-digestion of sugarcane press mud with vinasse on methane yield.

Science.gov (United States)

López González, Lisbet Mailin; Pereda Reyes, Ileana; Romero Romero, Osvaldo

2017-10-01

The conversion efficiency of high solids waste digestion as sugarcane press mud (P) may be limited due to hydrolysis step. The option of co-digestion with vinasse, main liquid waste generated from ethanol production, was investigated under batch regime at mesophilic conditions (37.5±1°C) and the best mixture was evaluated under semicontinuous regime in stirred-tank reactors. The maximum values for methane yield in batch tests were for V 75 /P 25 and V 50 /P 50 mixtures (on basis of the chemical oxygen demand (COD) percentage added in the mixture), with an average value of 246NmL CH 4 g -1 COD fed , which was 13% higher than that of press mud alone. A highest methane production rate of 69.6NmL CH 4 g -1 COD fed -1 d -1 was obtained for the mixtureV 75 /P 25 . During the experiment carried out in CSTR reactors, the organic loading rate (OLR) was increased from 0.5 up to 2.2gVSL -1 d -1 . Methane yields of 365L CH 4 kg -1 VS and biogas productivities of 1.6LL -1 were obtained in co-digestion, which was 64% higher in comparison to mono-digestion. The performance of the process in mono-digestion was less stable than in co-digestion, with a significant fall of methane yield to 1.8kgVSm -3 d -1 , and a partial inhibition of the methanogenic archaeas when the OLR was increased up to 2.2kgVSm -3 d -1 . The co-digestion of vinasse with press mud is a good option for the treatment of streams at the alcohol-sugar industry. Copyright © 2017 Elsevier Ltd. All rights reserved.

Real-time analysis of δ13C- and δD-CH4 by high precision laser spectroscopy

Science.gov (United States)

Eyer, Simon; Emmenegger, Lukas; Tuzson, Béla; Fischer, Hubertus; Mohn, Joachim

2014-05-01

Methane (CH4) is the most important non-CO2 greenhouse gas (GHG) contributing 18% to total radiative forcing. Anthropogenic sources (e.g. ruminants, landfills) contribute 60% to total emissions and led to an increase in its atmospheric mixing ratio from 700 ppb in pre-industrial times to 1819 ± 1 ppb in 2012 [1]. Analysis of the most abundant methane isotopologues 12CH4, 13CH4 and 12CH3D can be used to disentangle the various source/sink processes [2] and to develop target oriented reduction strategies. High precision isotopic analysis of CH4 can be accomplished by isotope-ratio mass-spectrometry (IRMS) [2] and more recently by mid-infrared laser-based spectroscopic techniques. For high precision measurements in ambient air, however, both techniques rely on preconcentration of the target gas [3]. In an on-going project, we developed a fully-automated, field-deployable CH4 preconcentration unit coupled to a dual quantum cascade laser absorption spectrometer (QCLAS) for real-time analysis of CH4 isotopologues. The core part of the rack-mounted (19 inch) device is a highly-efficient adsorbent trap attached to a motorized linear drive system and enclosed in a vacuum chamber. Thereby, the adsorbent trap can be decoupled from the Stirling cooler during desorption for fast desorption and optimal heat management. A wide variety of adsorbents, including: HayeSep D, molecular sieves as well as the novel metal-organic frameworks and carbon nanotubes were characterized regarding their surface area, isosteric enthalpy of adsorption and selectivity for methane over nitrogen. The most promising candidates were tested on the preconcentration device and a preconcentration by a factor > 500 was obtained. Furthermore analytical interferants (e.g. N2O, CO2) are separated by step-wise desorption of trace gases. A QCL absorption spectrometer previously described by Tuzson et al. (2010) for CH4 flux measurements was modified to obtain a platform for high precision and simultaneous

A simulation model for methane emissions from landfills with interaction of vegetation and cover soil.

Science.gov (United States)

Bian, Rongxing; Xin, Danhui; Chai, Xiaoli

2018-01-01

Global climate change and ecological problems brought about by greenhouse gas effect have become a severe threat to humanity in the 21st century. Vegetation plays an important role in methane (CH 4 ) transport, oxidation and emissions from municipal solid waste (MSW) landfills as it modifies the physical and chemical properties of the cover soil, and transports CH 4 to the atmosphere directly via their conduits, which are mainly aerenchymatous structures. In this study, a novel 2-D simulation CH 4 emission model was established, based on an interactive mechanism of cover soil and vegetation, to model CH 4 transport, oxidation and emissions in landfill cover soil. Results of the simulation model showed that the distribution of CH 4 concentration and emission fluxes displayed a significant difference between vegetated and non-vegetated areas. CH 4 emission flux was 1-2 orders of magnitude higher than bare areas in simulation conditions. Vegetation play a negative role in CH 4 emissions from landfill cover soil due to the strong CH 4 transport capacity even though vegetation also promotes CH 4 oxidation via changing properties of cover soil and emitting O 2 via root system. The model will be proposed to allow decision makers to reconsider the actual CH 4 emission from vegetated and non-vegetated covered landfills. Copyright © 2017 Elsevier Ltd. All rights reserved.

Evidence for methane production by marine algae (Emiliana huxleyi) and its implication for the methane paradox in oxic waters

Science.gov (United States)

Lenhart, K.; Klintzsch, T.; Langer, G.; Nehrke, G.; Bunge, M.; Schnell, S.; Keppler, F.

2015-12-01

Methane (CH4), an important greenhouse gas that affects radiation balance and consequently the earth's climate, still has uncertainties in its sinks and sources. The world's oceans are considered to be a source of CH4 to the atmosphere, although the biogeochemical processes involved in its formation are not fully understood. Several recent studies provided strong evidence of CH4 production in oxic marine and freshwaters but its source is still a topic of debate. Studies of CH4 dynamics in surface waters of oceans and large lakes have concluded that pelagic CH4 supersaturation cannot be sustained either by lateral inputs from littoral or benthic inputs alone. However, frequently regional and temporal oversaturation of surface waters occurs. This comprises the observation of a CH4 oversaturating state within the surface mixed layer, sometimes also termed the "oceanic methane paradox". In this study we considered marine algae as a possible direct source of CH4. Therefore, the coccolithophore Emiliania huxleyi was grown under controlled laboratory conditions and supplemented with two 13C-labelled carbon substrates, namely bicarbonate and a position-specific 13C-labelled methionine (R-S-13CH3). The CH4 production was 0.7 μg POC g-1 d-1, or 30 ng g-1 POC h-1. After supplementation of the cultures with the 13C labelled substrate, the isotope label was observed in headspace-CH4. Moreover, the absence of methanogenic archaea within the algal culture and the oxic conditions during CH4 formation suggest that marine algae such as Emiliania huxleyi contribute to the observed spatial and temporal restricted CH4 oversaturation in ocean surface waters.

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).

Science.gov (United States)

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

CH4 fluxes across the seafloor at three district gas hydrate fields: Impacts on ocean and atmosphere chemistry

Energy Technology Data Exchange (ETDEWEB)

Kastner, M.; Bartlett, D.; MacDonald, I.; Solomon, E.

2005-07-01

The role of methane hydrate in the global methane budget is poorly documented because relatively little is known about the transport of methane through the seafloor into the ocean and atmosphere, and the extent of en route water-column methanotrophy. Pore fluids and water column samples within and adjacent to methane plumes were analyzed for methane, dissolved inorganic C (DIC), sulfide/sulfate, alkalinity, and major element concentrations, and for delta{sup 13}C-CH4 and DIC, at three distinct gas hydrate environments. The three environments are: Bush Hill (BH) in the northern Gulf of Mexico (GOM), Eel River (ER) offshore Northern California, and North and South Hydrate Ridges (HR), Cascadia, Oregon margin. The methane source at these sites ranges from mostly thermogenic at GOM to primarily biogenic at HR. At these three distinct gas hydrate environments, at all the sites a significant enrichment in {sup 13}C-CH4 along isopycnals away from the methane plumes is observed, indicating extensive aerobic bacterial methane oxidation in the water column, and correspondingly of oxygen consumption. This is principally pronounced in the mostly biogenic methane setting. The delta{sup 13}C-CH4 values range from approx. 12 to -67 , PDB, at the Hydrate Ridges, from approx. 34 to -52 at Eel River, and from approx. 41 to -67 at Bush Hill. The large variation in methane C isotope ranges between the sites suggests that major differences exist in both the rates of aerobic methane oxidation and system openness at the studied locations. Methane fluxes across the sediment/seawater interface were measured, with a flux meter, MOSQUITO (Multiple Orifice Sampler and Quantitative Injection Tracer Observers) only at BH (Solomon et al., 2005). Water column methane concentrations are on average lower at HR than at ER and GOM. Preliminary estimates suggests that aerobic oxidation is nearly complete, consumes most to all of the water column methane at HR, but at the GOM only approx. 80% to a

Methane emissions from rice paddies : experiments and modelling

NARCIS (Netherlands)

Bodegom, van P.M.

2000-01-01

This thesis describes model development and experimentation on the comprehension and prediction of methane (CH ₄ ) emissions from rice paddies. The large spatial and temporal variability in CH ₄ emissions and the dynamic non-linear relationships

Effect of total solids content on methane and volatile fatty acid production in anaerobic digestion of food waste.

Science.gov (United States)

Liotta, Flavia; d'Antonio, Giuseppe; Esposito, Giovanni; Fabbricino, Massimiliano; van Hullebusch, Eric D; Lens, Piet N L; Pirozzi, Francesco; Pontoni, Ludovico

2014-10-01

This work investigates the role of the moisture content on anaerobic digestion of food waste, as representative of rapidly biodegradable substrates, analysing the role of volatile fatty acid production on process kinetics. A range of total solids from 4.5% to 19.2% is considered in order to compare methane yields and kinetics of reactors operated under wet to dry conditions. The experimental results show a reduction of the specific final methane yield of 4.3% and 40.8% in semi-dry and dry conditions compared with wet conditions. A decreasing trend of the specific initial methane production rate is observed when increasing the total solids concentration. Because of lack of water, volatile fatty acids accumulation occurs during the first step of the process at semi-dry and dry conditions, which is considered to be responsible for the reduction of process kinetic rates. The total volatile fatty acids concentration and speciation are proposed as indicators of process development at different total solids content. © The Author(s) 2014.

Adsorption kinetics of CO2, CH4, and their equimolar mixture on coal from the Black Warrior Basin, West-Central Alabama

Science.gov (United States)

Gruszkiewicz, M.S.; Naney, M.T.; Blencoe, J.G.; Cole, D.R.; Pashin, J.C.; Carroll, R.E.

2009-01-01

Laboratory experiments were conducted to investigate the adsorption kinetic behavior of pure and mixed gases (CO2, CH4, approximately equimolar CO2 + CH4 mixtures, and He) on a coal sample obtained from the Black Warrior Basin at the Littleton Mine (Twin Pine Coal Company), Jefferson County, west-central Alabama. The sample was from the Mary Lee coal zone of the Pottsville Formation (Lower Pennsylvanian). Experiments with three size fractions (45-150????m, 1-2??mm, and 5-10??mm) of crushed coal were performed at 40????C and 35????C over a pressure range of 1.4-6.9??MPa to simulate coalbed methane reservoir conditions in the Black Warrior Basin and provide data relevant for enhanced coalbed methane recovery operations. The following key observations were made: (1) CO2 adsorption on both dry and water-saturated coal is much more rapid than CH4 adsorption; (2) water saturation decreases the rates of CO2 and CH4 adsorption on coal surfaces, but it appears to have minimal effects on the final magnitude of CO2 or CH4 adsorption if the coal is not previously exposed to CO2; (3) retention of adsorbed CO2 on coal surfaces is significant even with extreme pressure cycling; and (4) adsorption is significantly faster for the 45-150????m size fraction compared to the two coarser fractions. ?? 2008 Elsevier B.V.

Ultimate methane yield from beef cattle manure: effect of temperature, ration constituents, antibiotics and manure age

Energy Technology Data Exchange (ETDEWEB)

Hashimoto, A G; Varel, V H; Chen, Y R

1981-10-01

The effects of temperature, ration constituents, antibiotics and manure age on the ultimate methane yield (Bo, litre CH4/g volatile solids fed (VSf)) were investigated using 4-litre batch fermenters. The average Bo for fermenters maintained at 30-60 degrees Celcius (at 5 degrees Celcius intervals) was 0.328 litre CH4/g VSf. The Bo at 65 degrees Celcius averaged 0.118 litre CH4g VSf, but this low yield was attributed to unstable fermentation rather than decreased substrate availability at that temperature. These results agreed well with Bo values estimated from daily-fed fermenters. Chlortetracycline and monensin did not affect Bo; however, monensin did delay the start of active fermentation in batch fermenters. The average Bo of manure from cattle fed 91.5, 40 and 7% corn silage were 0.173, 0.232 and 0.290 litre CH4/g VSf, respectively. The average Bo for 6-8 week old manure from a dirt feedlot was 0.210 litre CH4/g VSf. (Refs. 14).

Experimental study of the structure of rich premixed 1,3-butadiene/CH4/O2/Ar flame

OpenAIRE

Gueniche, Hadj-Ali; Glaude, Pierre-Alexandre; Fournet, René; Battin-Leclerc, Frédérique

2007-01-01

The structure of a laminar rich premixed 1,3-C4H6/CH4/O2/Ar flame have been investigated. 1,3-Butadiene, methane, oxygen and argon mole fractions are 0.033; 0.2073; 0.3315, and 0.4280, respectively, for an equivalent ratio of 1.80. The flame has been stabilized on a burner at a pressure of 6.7 kPa (50 Torr). The concentration profiles of stable species were measured by gas chromatography after sampling with a quartz probe. Quantified species included carbon monoxide and dioxide, methane, oxyg...

The 4-Corners methane hotspot: Mapping CH4 plumes at 60km through 1m resolution using space- and airborne spectrometers

Science.gov (United States)

Frankenberg, C.; Thorpe, A. K.; Hook, S. J.; Green, R. O.; Thompson, D. R.; Kort, E. A.; Hulley, G. C.; Vance, N.; Bue, B. D.; Aubrey, A. D.

2015-12-01

The SCIAMACHY instrument onboard the European research satellite ENVISAT detected a large methane hotspot in the 4-Corners area, specifically in New Mexico and Colorado. Total methane emissions in this region were estimated to be on the order of 0.5Tg/yr, presumably related to coal-bed methane exploration. Here, we report on NASA efforts to augment the TOPDOWN campaign intended to enable regional methane source inversions and identify source types in this area. The Jet Propulsion Laboratory was funded to fly two airborne imaging spectrometers, viz. AVIRIS-NG and HyTES. In April 2015, we used both instruments to continuously map about 2000km2 in the 4-Corners area at 1-5m spatial resolution, with special focus on the most enhanced areas as observed from space. During our weeklong campaign, we detected more than 50 isolated and strongly enhanced methane plumes, ranging from coal mine venting shafts and gas processing facilities through individual well-pads, pipeline leaks and outcrop. Results could be immediately shared with ground-based teams and TOPDOWN aircraft so that ground-validation and identification was feasible for a number of sources. We will provide a general overview of the JPL-led mapping campaign efforts and show individual results, derive source strength estimates and discuss how the results fit in with space borne estimates.

Effects of two common macrophytes on methane dynamics in freshwater sediments

NARCIS (Netherlands)

Van der Nat, F.J.; Middelburg, J.J.

1998-01-01

The methane cycle in constructed wetlands without plants and with Phragmites australis (reed) and Scirpus lacustris (bulrush) was investigated. Variations in CH4 production largely determined variations in CH4 emission among the systems: rather than variations in CH4 storage and oxidation. Twofold

Methanogenic Conversion of CO2 Into CH4

Energy Technology Data Exchange (ETDEWEB)

Stevens, S.H., Ferry, J.G., Schoell, M.

2012-05-06

This SBIR project evaluated the potential to remediate geologic CO2 sequestration sites into useful methane gas fields by application of methanogenic bacteria. Such methanogens are present in a wide variety of natural environments, converting CO2 into CH4 under natural conditions. We conclude that the process is generally feasible to apply within many of the proposed CO2 storage reservoir settings. However, extensive further basic R&D still is needed to define the precise species, environments, nutrient growth accelerants, and economics of the methanogenic process. Consequently, the study team does not recommend Phase III commercial application of the technology at this early phase.

Accuracy of noninvasive breath methane measurements using Fourier transform infrared methods on individual cows

DEFF Research Database (Denmark)

Lassen, Jan; Løvendahl, Peter; Madsen, Jørgen

2012-01-01

Individual methane (CH4) production was recorded repeatedly on 93 dairy cows during milking in an automatic milking system (AMS), with the aim of estimating individual cow differences in CH4 production. Methane and CO2 were measured with a portable air sampler and analyzer unit based on Fourier...

Variations in the methane budget over the last two millennia

NARCIS (Netherlands)

Sapart, C.J.

2012-01-01

Methane (CH4) is a strong greenhouse gas and even though its atmospheric abundance is lower than carbon dioxide (CO2), CH4 has a global warming potential twenty-five times larger than CO2 and its atmospheric abundance has drastically increased since 1800. Understanding the evolution of the CH4

Trace methane oxidation and the methane dependency of sulfate reduction in anaerobic granular sludge

KAUST Repository

Meulepas, Roel J.W.

2010-05-01

This study investigates the oxidation of labeled methane (CH4) and the CH4 dependence of sulfate reduction in three types of anaerobic granular sludge. In all samples, 13C-labeled CH4 was anaerobically oxidized to 13C-labeled CO2, while net endogenous CH4 production was observed. Labeled-CH4 oxidation rates followed CH4 production rates, and the presence of sulfate hampered both labeled-CH4 oxidation and methanogenesis. Labeled-CH4 oxidation was therefore linked to methanogenesis. This process is referred to as trace CH4 oxidation and has been demonstrated in methanogenic pure cultures. This study shows that the ratio between labeled-CH4 oxidation and methanogenesis is positively affected by the CH4 partial pressure and that this ratio is in methanogenic granular sludge more than 40 times higher than that in pure cultures of methanogens. The CH4 partial pressure also positively affected sulfate reduction and negatively affected methanogenesis: a repression of methanogenesis at elevated CH4 partial pressures confers an advantage to sulfate reducers that compete with methanogens for common substrates, formed from endogenous material. The oxidation of labeled CH 4 and the CH4 dependence of sulfate reduction are thus not necessarily evidence of anaerobic oxidation of CH4 coupled to sulfate reduction. © 2010 Federation of European Microbiological Societies.

Field-scale operation of methane biofiltration systems to mitigate point source methane emissions

International Nuclear Information System (INIS)

Hettiarachchi, Vijayamala C.; Hettiaratchi, Patrick J.; Mehrotra, Anil K.; Kumar, Sunil

2011-01-01

Methane biofiltration (MBF) is a novel low-cost technique for reducing low volume point source emissions of methane (CH 4 ). MBF uses a granular medium, such as soil or compost, to support the growth of methanotrophic bacteria responsible for converting CH 4 to carbon dioxide (CO 2 ) and water (H 2 O). A field research program was undertaken to evaluate the potential to treat low volume point source engineered CH 4 emissions using an MBF at a natural gas monitoring station. A new comprehensive three-dimensional numerical model was developed incorporating advection-diffusive flow of gas, biological reactions and heat and moisture flow. The one-dimensional version of this model was used as a guiding tool for designing and operating the MBF. The long-term monitoring results of the field MBF are also presented. The field MBF operated with no control of precipitation, evaporation, and temperature, provided more than 80% of CH 4 oxidation throughout spring, summer, and fall seasons. The numerical model was able to predict the CH 4 oxidation behavior of the field MBF with high accuracy. The numerical model simulations are presented for estimating CH 4 oxidation efficiencies under various operating conditions, including different filter bed depths and CH 4 flux rates. The field observations as well as numerical model simulations indicated that the long-term performance of MBFs is strongly dependent on environmental factors, such as ambient temperature and precipitation. - Highlights: → One-dimensional version of the model was used as a guiding tool for designing and operating the MBF. → Mathematical model predicted CH 4 oxidation behaviors of the field MBF with high accuracy i.e. (> 80 %). → Performance of MBF is dependent on ambient temperature and precipitation. - The developed numerical model simulations and field observations for estimating CH 4 oxidation efficiencies under various operating conditions indicate that the long-term performance of MBFs is strongly

Indigenous microbial capability in solid manure residues to start-up solid-phase anaerobic digesters.

Science.gov (United States)

Yap, S D; Astals, S; Jensen, P D; Batstone, D J; Tait, S

2017-06-01

Batch solid-phase anaerobic digestion is a technology for sustainable on-farm treatment of solid residues, but is an emerging technology that is yet to be optimised with respect to start-up and inoculation. In the present study, spent bedding from two piggeries (site A and B) were batch digested at total solids (TS) concentration of 5, 10 and 20% at mesophilic (37°C) and thermophilic (55°C) temperatures, without adding an external inoculum. The results showed that the indigenous microbial community present in spent bedding was able to recover the full methane potential of the bedding (140±5 and 227±6L CH 4 kgVS fed -1 for site A and B, respectively), but longer treatment times were required than for digestion with an added external inoculum. Nonetheless, at high solid loadings (i.e. TS level>10%), the digestion performance was affected by chemical inhibition due to ammonia and/or humic acid. Thermophilic temperatures did not influence digestion performance but did increase start-up failure risk. Further, inoculation of residues from the batch digestion to subsequent batch enhanced start-up and achieved full methane potential recovery of the bedding. Inoculation with liquid residue (leachate) was preferred over a solid residue, to preserve treatment capacity for fresh substrate. Overall, the study highlighted that indigenous microbial community in the solid manure residue was capable of recovering full methane potential and that solid-phase digestion was ultimately limited by chemical inhibition rather than lack of suitable microbial community. Copyright © 2017 Elsevier Ltd. All rights reserved.

Optimisation of expansion liquefaction processes using mixed refrigerant N_2–CH_4

International Nuclear Information System (INIS)

Ding, He; Sun, Heng; He, Ming

2016-01-01

Highlights: • A refrigerant composition matching method for N_2–CH_4 expansion processes. • Efficiency improvements for propane pre-cooled N_2–CH_4 expansion processes. • The process shows good adaptability to varying natural gas compositions. - Abstract: An expansion process with a pre-cooling system is simulated and optimised by Aspen HYSYS and MATLAB"™. Taking advantage of higher specific refrigeration effect of methane and easily reduced refrigeration temperature of nitrogen, the designed process adopts N_2–CH_4 as a mixed refrigerant. Based on the different thermodynamic properties and sensitivity difference of N_2 and CH_4 over the same heat transfer temperature range, this work proposes a novel method of matching refrigerant composition which aims at single-stage or multi-stage series expansion liquefaction processes with pre-cooling systems. This novel method is applied successfully in propane pre-cooled N_2–CH_4 expansion process, and the unit power consumption is reduced to 7.09 kWh/kmol, which is only 5.35% higher than the global optimised solutions obtained by genetic algorithm. This novel method can fulfil the accomplishments of low energy consumption and high liquefaction rate, and thus decreases the gap between the mixed refrigerant and expansion processes in energy consumption. Furthermore, the high exergy efficiency of the process indicates good adaptability to varying natural gas compositions.

A Single-Culture Bioprocess of Methanothermobacter thermautotrophicus to Upgrade Digester Biogas by CO2-to-CH4 Conversion with H2

Science.gov (United States)

Martin, Matthew R.; Fornero, Jeffrey J.; Angenent, Largus T.

2013-01-01

We optimized and tested a postbioprocessing step with a single-culture archaeon to upgrade biogas (i.e., increase methane content) from anaerobic digesters via conversion of CO2 into CH4 by feeding H2 gas. We optimized a culture of the thermophilic methanogen Methanothermobacter thermautotrophicus using: (1) a synthetic H2/CO2 mixture; (2) the same mixture with pressurization; (3) a synthetic biogas with different CH4 contents and H2; and (4) an industrial, untreated biogas and H2. A laboratory culture with a robust growth (dry weight of 6.4–7.4 g/L; OD600 of 13.6–15.4), a volumetric methane production rate of 21 L/L culture-day, and a H2 conversion efficiency of 89% was moved to an industrial anaerobic digester facility, where it was restarted and fed untreated biogas with a methane content of ~70% at a rate such that CO2 was in excess of the stoichiometric requirements in relation to H2. Over an 8-day operating period, the dry weight of the culture initially decreased slightly before stabilizing at an elevated level of ~8 g/L to achieve a volumetric methane production rate of 21 L/L culture-day and a H2 conversion efficiency of 62%. While some microbial contamination of the culture was observed via microscopy, it did not affect the methane production rate of the culture. PMID:24194675

A Single-Culture Bioprocess of Methanothermobacter thermautotrophicus to Upgrade Digester Biogas by CO2-to-CH4 Conversion with H2

Directory of Open Access Journals (Sweden)

Matthew R. Martin

2013-01-01

Full Text Available We optimized and tested a postbioprocessing step with a single-culture archaeon to upgrade biogas (i.e., increase methane content from anaerobic digesters via conversion of CO2 into CH4 by feeding H2 gas. We optimized a culture of the thermophilic methanogen Methanothermobacter thermautotrophicus using: (1 a synthetic H2/CO2 mixture; (2 the same mixture with pressurization; (3 a synthetic biogas with different CH4 contents and H2; and (4 an industrial, untreated biogas and H2. A laboratory culture with a robust growth (dry weight of 6.4–7.4 g/L; OD600 of 13.6–15.4, a volumetric methane production rate of 21 L/L culture-day, and a H2 conversion efficiency of 89% was moved to an industrial anaerobic digester facility, where it was restarted and fed untreated biogas with a methane content of ~70% at a rate such that CO2 was in excess of the stoichiometric requirements in relation to H2. Over an 8-day operating period, the dry weight of the culture initially decreased slightly before stabilizing at an elevated level of ~8 g/L to achieve a volumetric methane production rate of 21 L/L culture-day and a H2 conversion efficiency of 62%. While some microbial contamination of the culture was observed via microscopy, it did not affect the methane production rate of the culture.

Potential for methane production from anaerobic co-digestion of swine manure with winery wastewater.

Science.gov (United States)

Riaño, B; Molinuevo, B; García-González, M C

2011-03-01

This work examines the methane production potential for the anaerobic co-digestion of swine manure (SM) with winery wastewater (WW). Batch and semi-continuous experiments were carried out under mesophilic conditions. Batch experiments revealed that the highest specific methane yield was 348 mL CH(4)g(-1) COD added, obtained at 85.4% of WW and 0.7 g COD g(-1)VS. Specific methane yield from SM alone was 27 mL CH(4)g(-1) COD added d(-1). Furthermore, specific methane yields were 49, 87 and 107 mL CH(4)g(-1) COD added d(-1) for the reactors co-digesting mixtures with 10% WW, 25% WW and 40% WW, respectively. Co-digestion with 40% WW improved the removal efficiencies up to 52% (TCOD), 132% (SCOD) and 61% (VSS) compared to SM alone. These results suggest that methane can be produced very efficiently by the co-digestion of swine manure with winery wastewater. Copyright © 2011 Elsevier Ltd. All rights reserved.

Observation of Binding and Rotation of Methane and Hydrogen within a Functional Metal–Organic Framework

KAUST Repository

Savage, Mathew; da Silva, Ivan; Johnson, Mark; Carter, Joseph H.; Newby, Ruth; Suetin, Mikhail; Besley, Elena; Manuel, Pascal; Rudić, Svemir; Fitch, Andrew N.; Murray, Claire; David, William I. F.; Yang, Sihai; Schrö der, Martin

2016-01-01

The key requirement for a portable store of natural gas is to maximize the amount of gas within the smallest possible space. The packing of methane (CH4) in a given storage medium at the highest possible density is, therefore, a highly desirable but challenging target. We report a microporous hydroxyl-decorated material, MFM-300(In) (MFM = Manchester Framework Material, replacing the NOTT designation), which displays a high volumetric uptake of 202 v/v at 298 K and 35 bar for CH4 and 488 v/v at 77 K and 20 bar for H2. Direct observation and quantification of the location, binding, and rotational modes of adsorbed CH4 and H2 molecules within this host have been achieved, using neutron diffraction and inelastic neutron scattering experiments, coupled with density functional theory (DFT) modeling. These complementary techniques reveal a very efficient packing of H2 and CH4 molecules within MFM-300(In), reminiscent of the condensed gas in pure component crystalline solids. We also report here, for the first time, the experimental observation of a direct binding interaction between adsorbed CH4 molecules and the hydroxyl groups within the pore of a material. This is different from the arrangement found in CH4/water clathrates, the CH4 store of nature.

Observation of Binding and Rotation of Methane and Hydrogen within a Functional Metal–Organic Framework

KAUST Repository

Savage, Mathew

2016-07-27

The key requirement for a portable store of natural gas is to maximize the amount of gas within the smallest possible space. The packing of methane (CH4) in a given storage medium at the highest possible density is, therefore, a highly desirable but challenging target. We report a microporous hydroxyl-decorated material, MFM-300(In) (MFM = Manchester Framework Material, replacing the NOTT designation), which displays a high volumetric uptake of 202 v/v at 298 K and 35 bar for CH4 and 488 v/v at 77 K and 20 bar for H2. Direct observation and quantification of the location, binding, and rotational modes of adsorbed CH4 and H2 molecules within this host have been achieved, using neutron diffraction and inelastic neutron scattering experiments, coupled with density functional theory (DFT) modeling. These complementary techniques reveal a very efficient packing of H2 and CH4 molecules within MFM-300(In), reminiscent of the condensed gas in pure component crystalline solids. We also report here, for the first time, the experimental observation of a direct binding interaction between adsorbed CH4 molecules and the hydroxyl groups within the pore of a material. This is different from the arrangement found in CH4/water clathrates, the CH4 store of nature.

Observing and modeling links between soil moisture, microbes and CH4 fluxes from forest soils

Science.gov (United States)

Christiansen, Jesper; Levy-Booth, David; Barker, Jason; Prescott, Cindy; Grayston, Sue

2017-04-01

Soil moisture is a key driver of methane (CH4) fluxes in forest soils, both of the net uptake of atmospheric CH4 and emission from the soil. Climate and land use change will alter spatial patterns of soil moisture as well as temporal variability impacting the net CH4 exchange. The impact on the resultant net CH4 exchange however is linked to the underlying spatial and temporal distribution of the soil microbial communities involved in CH4 cycling as well as the response of the soil microbial community to environmental changes. Significant progress has been made to target specific CH4 consuming and producing soil organisms, which is invaluable in order to understand the microbial regulation of the CH4 cycle in forest soils. However, it is not clear as to which extent soil moisture shapes the structure, function and abundance of CH4 specific microorganisms and how this is linked to observed net CH4 exchange under contrasting soil moisture regimes. Here we report on the results from a research project aiming to understand how the CH4 net exchange is shaped by the interactive effects soil moisture and the spatial distribution CH4 consuming (methanotrophs) and producing (methanogens). We studied the growing season variations of in situ CH4 fluxes, microbial gene abundances of methanotrophs and methanogens, soil hydrology, and nutrient availability in three typical forest types across a soil moisture gradient in a temperate rainforest on the Canadian Pacific coast. Furthermore, we conducted laboratory experiments to determine whether the net CH4 exchange from hydrologically contrasting forest soils responded differently to changes in soil moisture. Lastly, we modelled the microbial mediation of net CH4 exchange along the soil moisture gradient using structural equation modeling. Our study shows that it is possible to link spatial patterns of in situ net exchange of CH4 to microbial abundance of CH4 consuming and producing organisms. We also show that the microbial

Direct methane and nitrous oxide emissions of South African dairy ...

African Journals Online (AJOL)

The enteric methane emission factors for dairy cattle of 76.4 kg CH4/head/year and 71.8 kg CH4/head/year for concentrate fed and pasture-based production systems, respectively, were higher than those reported by other developing countries, as well as the IPCC default value of 46 kg CH4/head/year for developing ...

The integrated nitrous oxide and methane grassland project

Energy Technology Data Exchange (ETDEWEB)

Leffelaar, P.A.; Langeveld, C.A.; Hofman, J.E.; Segers, R.; Van den Pol-van Dasselaar, A.; Goudriaan, J.; Rabbinge, R.; Oenema, O. [Department of Theoretical Production Ecology, Wageningen Agricultural University, Wageningen (Netherlands)

2000-07-01

The integrated nitrous oxide (N{sub 2}O) and methane (CH{sub 4}) grassland project aims to estimate and explain emissions of these greenhouse gases from two ecosystems, namely drained agricultural peat soil under grass at the experimental farm Zegveld and undrained peat in the nature preserve Nieuwkoopse Plassen, both Netherlands. Peat soils were chosen because of their expected considerable contribution to the greenhouse gas budget considering the prevailing wet and partial anaerobic conditions. The emission dynamics of these ecosystems are considered representatives of large peat areas because the underlying processes are rather general and driven by variables like organic matter characteristics, water and nutrient conditions and type of vegetation. The research approach comprises measurements and modelling at different integration levels relating to the microbiology of the production and consumption of N{sub 2}O and CH{sub 4} (laboratory studies), their movement through peat soil (rhizolab and field studies), and the resulting fluxes (field studies). Typical emissions from drained soil were 15-40 kg ha{sup -1} y{sup -1} N{sub 2}O and virtually zero for CH{sub 4}. The undrained soil in the nature preserve emitted 100-280 kg ha{sup -1} y{sup -1} CH{sub 4}, and probably little N{sub 2}O. The process knowledge, collected and partly integrated in the models, helps to explain these data. For example, the low methane emission from drained peat can more coherently be understood and extrapolated because: (1) upper soil layers are aerobic, thus limiting methane production and stimulating methane oxidation, (2) absence of aerenchymatous roots of wetland plants that connect deeper anaerobic soil layers where methane is produced to the atmosphere and supply labile carbon, (3) a low methane production potential in deep layers due to the low decomposability of organic matter, and (4) long anaerobic periods needed in the topsoil to develop a methane production potential. This

Mitigation of methane emission from Fakse landfill using a biowindow system

DEFF Research Database (Denmark)

Scheutz, Charlotte; Fredenslund, Anders Michael; Chanton, Jeffrey

2011-01-01

Landfills are significant sources of atmospheric methane (CH4) that contributes to climate change, and therefore there is a need to reduce CH4 emissions from landfills. A promising cost efficient technology is to integrate compost into landfill covers (so-called “biocovers”) to enhance biological...... of biocover systems. The study also revealed that there still exist several challenges to better optimize the functionality. The most important challenges are to control gas flow and evenly distribute the gas into the biocovers.......Landfills are significant sources of atmospheric methane (CH4) that contributes to climate change, and therefore there is a need to reduce CH4 emissions from landfills. A promising cost efficient technology is to integrate compost into landfill covers (so-called “biocovers”) to enhance biological...

Large emissions from floodplain trees close the Amazon methane budget

Science.gov (United States)

Pangala, Sunitha R.; Enrich-Prast, Alex; Basso, Luana S.; Peixoto, Roberta Bittencourt; Bastviken, David; Hornibrook, Edward R. C.; Gatti, Luciana V.; Marotta, Humberto; Calazans, Luana Silva Braucks; Sakuragui, Cassia Mônica; Bastos, Wanderley Rodrigues; Malm, Olaf; Gloor, Emanuel; Miller, John Bharat; Gauci, Vincent

2017-12-01

Wetlands are the largest global source of atmospheric methane (CH4), a potent greenhouse gas. However, methane emission inventories from the Amazon floodplain, the largest natural geographic source of CH4 in the tropics, consistently underestimate the atmospheric burden of CH4 determined via remote sensing and inversion modelling, pointing to a major gap in our understanding of the contribution of these ecosystems to CH4 emissions. Here we report CH4 fluxes from the stems of 2,357 individual Amazonian floodplain trees from 13 locations across the central Amazon basin. We find that escape of soil gas through wetland trees is the dominant source of regional CH4 emissions. Methane fluxes from Amazon tree stems were up to 200 times larger than emissions reported for temperate wet forests and tropical peat swamp forests, representing the largest non-ebullitive wetland fluxes observed. Emissions from trees had an average stable carbon isotope value (δ13C) of -66.2 ± 6.4 per mil, consistent with a soil biogenic origin. We estimate that floodplain trees emit 15.1 ± 1.8 to 21.2 ± 2.5 teragrams of CH4 a year, in addition to the 20.5 ± 5.3 teragrams a year emitted regionally from other sources. Furthermore, we provide a ‘top-down’ regional estimate of CH4 emissions of 42.7 ± 5.6 teragrams of CH4 a year for the Amazon basin, based on regular vertical lower-troposphere CH4 profiles covering the period 2010-2013. We find close agreement between our ‘top-down’ and combined ‘bottom-up’ estimates, indicating that large CH4 emissions from trees adapted to permanent or seasonal inundation can account for the emission source that is required to close the Amazon CH4 budget. Our findings demonstrate the importance of tree stem surfaces in mediating approximately half of all wetland CH4 emissions in the Amazon floodplain, a region that represents up to one-third of the global wetland CH4 source when trees are combined with other emission sources.

Large emissions from floodplain trees close the Amazon methane budget.

Science.gov (United States)

Pangala, Sunitha R; Enrich-Prast, Alex; Basso, Luana S; Peixoto, Roberta Bittencourt; Bastviken, David; Hornibrook, Edward R C; Gatti, Luciana V; Marotta, Humberto; Calazans, Luana Silva Braucks; Sakuragui, Cassia Mônica; Bastos, Wanderley Rodrigues; Malm, Olaf; Gloor, Emanuel; Miller, John Bharat; Gauci, Vincent

2017-12-14

Wetlands are the largest global source of atmospheric methane (CH 4 ), a potent greenhouse gas. However, methane emission inventories from the Amazon floodplain, the largest natural geographic source of CH 4 in the tropics, consistently underestimate the atmospheric burden of CH 4 determined via remote sensing and inversion modelling, pointing to a major gap in our understanding of the contribution of these ecosystems to CH 4 emissions. Here we report CH 4 fluxes from the stems of 2,357 individual Amazonian floodplain trees from 13 locations across the central Amazon basin. We find that escape of soil gas through wetland trees is the dominant source of regional CH 4 emissions. Methane fluxes from Amazon tree stems were up to 200 times larger than emissions reported for temperate wet forests and tropical peat swamp forests, representing the largest non-ebullitive wetland fluxes observed. Emissions from trees had an average stable carbon isotope value (δ 13 C) of -66.2 ± 6.4 per mil, consistent with a soil biogenic origin. We estimate that floodplain trees emit 15.1 ± 1.8 to 21.2 ± 2.5 teragrams of CH 4 a year, in addition to the 20.5 ± 5.3 teragrams a year emitted regionally from other sources. Furthermore, we provide a 'top-down' regional estimate of CH 4 emissions of 42.7 ± 5.6 teragrams of CH 4 a year for the Amazon basin, based on regular vertical lower-troposphere CH 4 profiles covering the period 2010-2013. We find close agreement between our 'top-down' and combined 'bottom-up' estimates, indicating that large CH 4 emissions from trees adapted to permanent or seasonal inundation can account for the emission source that is required to close the Amazon CH 4 budget. Our findings demonstrate the importance of tree stem surfaces in mediating approximately half of all wetland CH 4 emissions in the Amazon floodplain, a region that represents up to one-third of the global wetland CH 4 source when trees are combined with other emission sources.

Russian boreal peatlands dominate the natural European methane budget

International Nuclear Information System (INIS)

Schneider, Julia; Jungkunst, Hermann F; Wolf, Ulrike; Schreiber, Peter; Kutzbach, Lars; Gazovic, Michal; Miglovets, Mikhail; Mikhaylov, Oleg; Grunwald, Dennis; Erasmi, Stefan; Wilmking, Martin

2016-01-01

About 60% of the European wetlands are located in the European part of Russia. Nevertheless, data on methane emissions from wetlands of that area are absent. Here we present results of methane emission measurements for two climatically different years from a boreal peatland complex in European Russia. Winter fluxes were well within the range of what has been reported for the peatlands of other boreal regions before, but summer fluxes greatly exceeded the average range of 5–80 mg CH 4 m −2 d −1 for the circumpolar boreal zone. Half of the measured fluxes ranged between 150 and 450 mg CH 4 m −2 d −1 . Extrapolation of our data to the whole boreal zone of European Russia shows that theses emissions could amount to up to 2.7 ± 1.1 Tg CH 4 a −1 , corresponding to 69% of the annual emissions from European wetlands or 33% of the total annual natural European methane emission. In 2008, climatic conditions corresponded to the long term mean, whereas the summer of 2011 was warmer and noticeably drier. Counterintuitively, these conditions led to even higher CH 4 emissions, with peaks up to two times higher than the values measured in 2008. As Russian peatlands dominate the areal extend of wetlands in Europe and are characterized by very high methane fluxes to the atmosphere, it is evident, that sound European methane budgeting will only be achieved with more insight into Russian peatlands. (letter)

Methane production rates from natural organics of glacial lake clay and granitic groundwater

Energy Technology Data Exchange (ETDEWEB)

Sheppard, M I; Stroes-Gascoyne, S; Hawkins, J L; Hamon, C J; Motycka, M

1996-05-01

Engineered barrier materials are an integral part of the proposed Canadian concept for the disposal of used nuclear fuel or high level waste. Components of these barriers, such as the buffer and backfill clays surrounding the waste containers in a vault, and granitic groundwater, naturally contain small quantities of organic material (up to about 1.2 wt%). Despite high temperatures, space and water limitations and radiation effects, the question remains whether gas could be produced from these organics as a result of biological processes. Degradation of organic carbon by microbes can produce gases such as carbon dioxide (C0{sub 2}) and methane (CH{sub 4}). This work demonstrates that methane is produced in natural systems containing < 6 mole % 0{sub 2}. In deep fracture zone groundwater, the largest methane production rate was 0.19 mole %/day or 5 {mu}g CH{sub 4}/L groundwater per day, at STP. This can be compared with the methane production rate of 1 {mu}g CH{sub 4}/(kg clay {center_dot} day) at STP in an earlier experiment containing added organic material. Using this rate of 5 pg CH{sub 4}/(L groundwater {center_dot} day) (3.75 {mu}g C/(L groundwater {center_dot} day)), all of the organic C in the groundwater, assuming it is equally bioavailable, would have been converted to CH{sub 4} during the timeframe of this experiment. Enhanced methane production occurred with an increase in natural organic carbon, an increase in the microbe population and with the addition of Fe. Steady-state methane production rates of 10 to 25 {mu}g CH{sub 4}/ L groundwater per day have been repeatedly observed in clay-free systems. The effects of microbial metabolism, the requirement for a facilitating consortium, the Eh, the pH, the salinity, the groundwater sulphate concentration, the presence of methanotrophs and the sorption effects of clay interlayers are discussed as possible explanations for the inhibition of methanogenesis and methane production in the presence of clay and

Rapid sediment accumulation results in high methane effluxes from coastal sediments

NARCIS (Netherlands)

Egger, M.J.|info:eu-repo/dai/nl/372629199; Lenstra, W.K.|info:eu-repo/dai/nl/411295977; Jong, Dirk; Meysman, Filip; Sapart, C.J.|info:eu-repo/dai/nl/31400596X; van der Veen, C.; Röckmann, Thomas|info:eu-repo/dai/nl/304838233; Gonzalez, Santiago; Slomp, C.P.|info:eu-repo/dai/nl/159424003

2016-01-01

Globally, the methane (CH4) efflux from the ocean to the atmosphere is small, despite high rates of CH4 production in continental shelf and slope environments. This low efflux results from the biological removal of CH4 through anaerobic oxidation with sulfate in marine sediments. In some settings,

Sensitivity of wetland methane emissions to model assumptions: application and model testing against site observations

Directory of Open Access Journals (Sweden)

L. Meng

2012-07-01

Full Text Available Methane emissions from natural wetlands and rice paddies constitute a large proportion of atmospheric methane, but the magnitude and year-to-year variation of these methane sources are still unpredictable. Here we describe and evaluate the integration of a methane biogeochemical model (CLM4Me; Riley et al., 2011 into the Community Land Model 4.0 (CLM4CN in order to better explain spatial and temporal variations in methane emissions. We test new functions for soil pH and redox potential that impact microbial methane production in soils. We also constrain aerenchyma in plants in always-inundated areas in order to better represent wetland vegetation. Satellite inundated fraction is explicitly prescribed in the model, because there are large differences between simulated fractional inundation and satellite observations, and thus we do not use CLM4-simulated hydrology to predict inundated areas. A rice paddy module is also incorporated into the model, where the fraction of land used for rice production is explicitly prescribed. The model is evaluated at the site level with vegetation cover and water table prescribed from measurements. Explicit site level evaluations of simulated methane emissions are quite different than evaluating the grid-cell averaged emissions against available measurements. Using a baseline set of parameter values, our model-estimated average global wetland emissions for the period 1993–2004 were 256 Tg CH₄ yr⁻¹ (including the soil sink and rice paddy emissions in the year 2000 were 42 Tg CH₄ yr⁻¹. Tropical wetlands contributed 201 Tg CH₄ yr⁻¹, or 78% of the global wetland flux. Northern latitude (>50 N systems contributed 12 Tg CH₄ yr⁻¹. However, sensitivity studies show a large range (150–346 Tg CH₄ yr⁻¹ in predicted global methane emissions (excluding emissions from rice paddies. The large range is

Methane cycling. Nonequilibrium clumped isotope signals in microbial methane.

Science.gov (United States)

Wang, David T; Gruen, Danielle S; Lollar, Barbara Sherwood; Hinrichs, Kai-Uwe; Stewart, Lucy C; Holden, James F; Hristov, Alexander N; Pohlman, John W; Morrill, Penny L; Könneke, Martin; Delwiche, Kyle B; Reeves, Eoghan P; Sutcliffe, Chelsea N; Ritter, Daniel J; Seewald, Jeffrey S; McIntosh, Jennifer C; Hemond, Harold F; Kubo, Michael D; Cardace, Dawn; Hoehler, Tori M; Ono, Shuhei

2015-04-24

Methane is a key component in the global carbon cycle, with a wide range of anthropogenic and natural sources. Although isotopic compositions of methane have traditionally aided source identification, the abundance of its multiply substituted "clumped" isotopologues (for example, (13)CH3D) has recently emerged as a proxy for determining methane-formation temperatures. However, the effect of biological processes on methane's clumped isotopologue signature is poorly constrained. We show that methanogenesis proceeding at relatively high rates in cattle, surface environments, and laboratory cultures exerts kinetic control on (13)CH3D abundances and results in anomalously elevated formation-temperature estimates. We demonstrate quantitatively that H2 availability accounts for this effect. Clumped methane thermometry can therefore provide constraints on the generation of methane in diverse settings, including continental serpentinization sites and ancient, deep groundwaters. Copyright © 2015, American Association for the Advancement of Science.

Study of HKUST (Copper benzene-1,3,5-tricarboxylate, Cu-BTC MOF)-1 metal organic frameworks for CH4 adsorption: An experimental Investigation with GCMC (grand canonical Monte-carlo) simulation

International Nuclear Information System (INIS)

Sun, Baichuan; Kayal, Sibnath; Chakraborty, Anutosh

2014-01-01

We have measured the methane uptakes on HKUST (Copper benzene-1,3,5-tricarboxylate, Cu-BTC MOF)-1 MOF (metal organic framework) for the temperatures ranging from 120 K to 300 K and pressures up to 10 bar. The experimentally measured HKUST-1 + CH 4 isotherms data are compared with uptakes of various adsorbents and methane systems. We have also simulated the methane uptakes and its density distribution on HKUST-1 employing GCMC (grand canonical Monte-carlo) simulation and compare with experimental data. In this article, we also present an extensive study on characterization and property evaluation of HKUST-1 MOF for CH 4 adsorption characteristics employing XRD (X-ray diffraction), SEM (scanning electron microscope) and TGA (thermo gravimetric analysis). Employing GCMC and the thermodynamic property fields of HKUST-1 + CH 4 system, the isosteric heat of adsorption (Q st ) is calculated and Q st is presented in a T-s (temperature-entropy) diagram. - Highlights: • Characterization of HKUST-1 MOFs by XRD, SEM, N 2 adsorption and TGA. • Measurement of CH 4 uptakes on HKUST-1 by volumetric methods. • GCMC simulation of methane uptakes and its density distribution on HKUST-1. • Isosteric heat of adsorption in a T-s (temperature-entropy) diagram

A combined H2/CH4 cold moderator for a short pulsed neutron source

International Nuclear Information System (INIS)

Williamson, K.D.; Lucas, A.T.

1989-01-01

Both the ISIS (Rutherford-Appleton Laboratory) spallation source and the Los Alamos Neutron Scattering Center (LANSCE) were designed to produce neutrons as a result of an 800-MeV proton beam being incident on a target. Both systems are intended to accept beam intensities up to 200 μA. Cryogenic moderators of liquid hydrogen and methane are either in use or are planned for service at both facilities. Very low temperature methane would be an ideal moderating material as it has a high hydrogen density and many low frequency modes, which facilitate thermalization. Such moderators are in service at two major world facilities, KEK (Japan) and Argonne National Laboratory (USA). Unfortunately, solid methane has very low thermal conductivity and is subject to radiation damage making a moderator of this type impractical for use in high-intensity beam, such as indicated above. This report outlines a possible alternative using small spheres of solid methane in a matrix of supercritical hydrogen at 25 K. 4 figs

Electron transport in liquids: effect of unbalancing the methane molecule by deuteration

International Nuclear Information System (INIS)

Floriano, M.A.; Freeman, G.R.

1983-01-01

The mobility of electrons in nonpolar liquids is strongly dependent on the molecular shape. In spherelike methane the mobility is three orders of magnitude greater than in the rodlike ethane. To investigate the enormous gap between methane and ethane, the effect of slightly perturbing the symmetry of the methane molecule by progressive deuterium substitution was studied. At temperatures near the triple point (T/Tsub(c) approximately 0.48) and near the mobility maximum (T/Tsub(c) approximately 0.93) the mobilities change in the order: CH 4 > CH 3 D > CH 2 D 2 3 approximately CD 4 . The differences are related to the symmetries of the molecules and to the rotational motions. (Authors)

Methane stable isotope distribution at a Carex dominated fen in North Central Alberta

Science.gov (United States)

Popp, Trevor J.; Chanton, Jeffrey P.; Whiting, Gary J.; Grant, Nick

1999-12-01

The methane stable isotope distribution was characterized at a Carex dominated fen in boreal Alberta, Canada, over three growing seasons to examine methane production, oxidation, and transport to the atmosphere; processes which are strongly tied to emergent vegetation and the influence of the rhizosphere (upper 20 cm of peat in this system]. At times when standing floodwater was present, δ13C values of emitted methane averaged -63.6 ± 2.3, -66.3 ± 1.6, and -65.4 ± 1.3‰ for the 1994, 1995, and 1996 seasons, respectively. These emissions were significantly 13C depleted relative to the belowground methane dissolved in rhizospheric pore waters, indicating that gas transport in Carex is dominated by passive diffusion. The rhizosphere was 13CH4 enriched relative to depths below the rhizosphere, consistent with the occurrence of root associated methane oxidation, preferential mobilization of 13CH4, and a relatively greater role of acetate fermentation type methane production. Dual isotope tracers, δ13C and δD, help qualify the role of each of these processes and aid in describing the distribution of production pathways, CO2 reduction, and acetate fermentation. Inverse trends in δ13C-CH4 and δD-CH4 depth profiles are consistent with an interpretation suggesting an evolution toward methane production by CO2 reduction with increasing depth. A shift in production mechanisms appears to be the dominate process affecting the stable isotope distribution below 10 cm in the peat column, while oxidation and transport isotope effects are dominant above 10 cm. To test several hypotheses regarding the effects of transport, oxidation, and production on methane isotope distributions, we also present measurements from sites fertilized and sites devegetated (continually clipped) over the 3 year period. Removal of vegetation quickly halted rhizospheric methane oxidation and gas transport while gradually increasing the relative role of CO2 reduction in net methane production as

The influence of nitrogen fertiliser rate and crop rotation on soil methane flux in rain-fed potato fields in Wuchuan County, China

International Nuclear Information System (INIS)

Wang, Liwei; Pan, Zhihua; Xu, Hui; Wang, Cheng; Gao, Lin; Zhao, Peiyi; Dong, Zhiqiang; Zhang, Jingting; Cui, Guohui; Wang, Sen; Han, Guolin; Zhao, Hui

2015-01-01

As one of the important greenhouse gases, the characteristics and principles of methane exchange characteristics in cultivated lands have become hot topics in current climate change research. This study examines the influences of nitrogen fertilisation, temperature and soil water content on methane exchange characteristic and methane exchange functional gene-pmoA gene abundance based on experimental observations of methane exchange fluxes using the static chamber–gas chromatographic method and measurements of methanotroph gene copy numbers in three growing periods by real-time PCR in rain-fed potato fields. The results indicate that the rain-fed potato fields were a CH_4 sink with an average annual methane absorption (negative emission) of 940.8 ± 103.2 g CH_4-C/ha/year. The cumulative methane absorption first exhibited flat and subsequently increasing trend with the increase of nitrogen fertilisation from 0 ~ 135 kg N·ha"−"1. Methane cumulative absorption significantly increased with the increase of temperature when temperatures were below 19.6 °C. Methane oxidation capacity (methanotroph pmoA gene copy numbers) showed an increasing and subsequently decreasing trend with the increase of soil moisture. Crop rotation was observed to increase the methane absorption in rain-fed potato fields and nearly one time higher than that under continuous cropping. A mechanism concept model of the methane exchange in rain-fed potato fields was advanced in this paper. - Highlights: • Rain-fed potato fields were a CH_4 sink. • Increased nitrogen fertilisation and temperature led to higher CH_4 absorption. • CH_4 oxidation capacity showed a parabolic trend with soil moisture increased. • Crop rotation increased CH_4 absorption one time higher than continuous cropping. • A mechanism concept model of the CH_4 exchange in potato fields was advanced.

The influence of nitrogen fertiliser rate and crop rotation on soil methane flux in rain-fed potato fields in Wuchuan County, China

Energy Technology Data Exchange (ETDEWEB)

Wang, Liwei [College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193 (China); College of Agronomy, Shenyang Agricultural University, Shenyang 110866 (China); Wuchuan Scientific Observing and Experimental Station of Agro-Environment, Ministry of Agriculture Wuchuan 011700 (China); Pan, Zhihua, E-mail: panzhihua@cau.edu.cn [College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193 (China); Wuchuan Scientific Observing and Experimental Station of Agro-Environment, Ministry of Agriculture Wuchuan 011700 (China); Xu, Hui [Institute of Applied Ecology, Chinese Academy of Sciences, Shenyang 110016 (China); Wang, Cheng [College of Agricultural and Biotechnology, China Agricultural University, Beijing 100193 (China); Gao, Lin [School of Resources and Environmental, Anhui Agricultural University, Hefei 230036 (China); Zhao, Peiyi [Institute of Resources Environmental and Detection Technology, Inner Mongolia Academy of Agricultural and Animal Husbandry Sciences, Huhhot 010031 (China); Wuchuan Scientific Observing and Experimental Station of Agro-Environment, Ministry of Agriculture Wuchuan 011700 (China); Dong, Zhiqiang; Zhang, Jingting; Cui, Guohui; Wang, Sen; Han, Guolin; Zhao, Hui [College of Resources and Environmental Sciences, China Agricultural University, Beijing 100193 (China); Wuchuan Scientific Observing and Experimental Station of Agro-Environment, Ministry of Agriculture Wuchuan 011700 (China)

2015-12-15

As one of the important greenhouse gases, the characteristics and principles of methane exchange characteristics in cultivated lands have become hot topics in current climate change research. This study examines the influences of nitrogen fertilisation, temperature and soil water content on methane exchange characteristic and methane exchange functional gene-pmoA gene abundance based on experimental observations of methane exchange fluxes using the static chamber–gas chromatographic method and measurements of methanotroph gene copy numbers in three growing periods by real-time PCR in rain-fed potato fields. The results indicate that the rain-fed potato fields were a CH{sub 4} sink with an average annual methane absorption (negative emission) of 940.8 ± 103.2 g CH{sub 4}-C/ha/year. The cumulative methane absorption first exhibited flat and subsequently increasing trend with the increase of nitrogen fertilisation from 0 ~ 135 kg N·ha{sup −1}. Methane cumulative absorption significantly increased with the increase of temperature when temperatures were below 19.6 °C. Methane oxidation capacity (methanotroph pmoA gene copy numbers) showed an increasing and subsequently decreasing trend with the increase of soil moisture. Crop rotation was observed to increase the methane absorption in rain-fed potato fields and nearly one time higher than that under continuous cropping. A mechanism concept model of the methane exchange in rain-fed potato fields was advanced in this paper. - Highlights: • Rain-fed potato fields were a CH{sub 4} sink. • Increased nitrogen fertilisation and temperature led to higher CH{sub 4} absorption. • CH{sub 4} oxidation capacity showed a parabolic trend with soil moisture increased. • Crop rotation increased CH{sub 4} absorption one time higher than continuous cropping. • A mechanism concept model of the CH{sub 4} exchange in potato fields was advanced.