Kinetics of methane fermentation yield in biogas reactors: Genetic variation and association with chemical composition in maize

International Nuclear Information System (INIS)

Grieder, Christoph; Mittweg, Greta; Dhillon, Baldev S.; Montes, Juan M.; Orsini, Elena; Melchinger, Albrecht E.

2012-01-01

Maize (Zea mays L.) is the most competitive crop for methane production in Germany. Methane fermentation yield per unit of dry matter (MFY) is a determinant of methane yield, but little information is available on this trait. Our objectives were to investigate the kinetics of MFY during fermentation of maize, estimate quantitative-genetic parameters for different traits related to MFY and examine the relationship of MFY with chemical composition and silage quality. Whole-plant material of 16 inbreds and their 32 testcrosses was analyzed for MFY over 35 days of fermentation using a discontinuous laboratory assay. Data were also generated on chemical composition and in vitro digestible organic matter (IVDOM). Significant genotypic variances and high heritabilities were observed for MFY at early fermentation stages (up to 5 days) probably due to different concentrations of easily degradable chemical components. However, genotypic variances and heritability of MFY reduced as fermentation progressed, because of complete or partial degradation of all chemical components. Further, there were strong correlations of MFY with chemical components at early fermentation stages but not at later stages. Therefore, MFY at later stages, which is closer to potential MFY, does not seem to be amenable to selection. High heritability of IVDOM and its strong correlation with MFY in testcrosses indicated its possible use for preliminary or indirect selection. Keeping in view the magnitude of genetic variance that was low for MFY and high for dry matter yield (DMY), the other component of methane yield, more emphasis on breeding for DMY seems appropriate. -- Highlights: ► We investigated methane fermentation yield (MFY) of diverse germplasm of maize. ► The kinetics of MFY and its correlations with chemical composition were examined. ► Genetic variance and heritability for MFY decreased with fermentation time. ► Complete fermentation (35 d) reduced correlations of MFY with chemical

Estimation of biogas and methane yields in an UASB treating potato starch processing wastewater with backpropagation artificial neural network.

Science.gov (United States)

Antwi, Philip; Li, Jianzheng; Boadi, Portia Opoku; Meng, Jia; Shi, En; Deng, Kaiwen; Bondinuba, Francis Kwesi

2017-03-01

Three-layered feedforward backpropagation (BP) artificial neural networks (ANN) and multiple nonlinear regression (MnLR) models were developed to estimate biogas and methane yield in an upflow anaerobic sludge blanket (UASB) reactor treating potato starch processing wastewater (PSPW). Anaerobic process parameters were optimized to identify their importance on methanation. pH, total chemical oxygen demand, ammonium, alkalinity, total Kjeldahl nitrogen, total phosphorus, volatile fatty acids and hydraulic retention time selected based on principal component analysis were used as input variables, whiles biogas and methane yield were employed as target variables. Quasi-Newton method and conjugate gradient backpropagation algorithms were best among eleven training algorithms. Coefficient of determination (R 2 ) of the BP-ANN reached 98.72% and 97.93% whiles MnLR model attained 93.9% and 91.08% for biogas and methane yield, respectively. Compared with the MnLR model, BP-ANN model demonstrated significant performance, suggesting possible control of the anaerobic digestion process with the BP-ANN model. Copyright © 2016 Elsevier Ltd. All rights reserved.

Methane yield enhancement via electroporation of organic waste.

Science.gov (United States)

Safavi, Seyedeh Masoumeh; Unnthorsson, Runar

2017-08-01

An experimental study with pulsed electric field (PEF) pre-treatment was conducted to investigate its effect on methane production. PEF pre-treatment converts organic solids into soluble and colloidal forms, increasing bioavailability for anaerobic microorganisms participating in methane generation process. The substrates tested were landfill leachate and fruit/vegetable. Three treatment intensities of 15, 30, and 50kWh/m 3 were applied to investigate the influence of pre-treatment on methane production via biochemical methane potential test. Threshold treatment intensity was found to be around 30kWh/m 3 for landfill leachate beyond which the methane production enhanced linearly with increase in intensity. Methane production of the landfill leachate significantly increased up to 44% with the highest intensity. The result of pulsed electric field pre-treatment on fruit/vegetable showed that 15kWh/m 3 was the intensity by which the highest amount of methane (up to 7%) was achieved. Beyond this intensity, the methane production decreased. Chemical oxygen demand removals were increased up to 100% for landfill leachate and 17% for fruit/vegetable, compared to the untreated slurries. Results indicate that the treatment intensity has a significant effect on the methane production and biosolid removal. Copyright © 2017 Elsevier Ltd. All rights reserved.

Improving the methane yield of maize straw: Focus on the effects of pretreatment with fungi and their secreted enzymes combined with sodium hydroxide.

Science.gov (United States)

Zhao, Xiaoling; Luo, Kai; Zhang, Yue; Zheng, Zehui; Cai, Yafan; Wen, Boting; Cui, Zongjun; Wang, Xiaofen

2018-02-01

In order to improve the methane yield, the alkaline and biological pretreatments on anaerobic digestion (AD) were investigated. Three treatments were tested: NaOH, biological (enzyme and fungi), and combined NaOH with biological. The maximum reducing sugar concentrations were obtained using Enzyme T (2.20 mg/mL) on the 6th day. The methane yield of NaOH + Enzyme A was 300.85 mL/g TS, 20.24% higher than the control. Methane yield obtained from Enzyme (T + A) and Enzyme T pretreatments were 277.03 and 273.75 mL/g TS, respectively, which were as effective as 1% NaOH (276.16 mL/g TS) in boosting methane production, and are environmentally friendly and inexpensive biological substitutes. Fungal pretreatment inhibited methane fermentation of maize straw, 15.68% was reduced by T + A compared with the control. The simultaneous reduction of DM, cellulose and hemicellulose achieved high methane yields. This study provides important guidance for the application of enzymes to AD from lignocellulosic agricultural waste. Copyright © 2017. Published by Elsevier Ltd.

Effect of Aqueous Ammonia Soaking on the methane yield and composition of digested manure fibers applying different ammonia concentrations and treatment durations

DEFF Research Database (Denmark)

Mirtsou-Xanthopoulou, Chrysoula; Jurado, Esperanza; Skiadas, Ioannis

2014-01-01

, their economical profitable operation relies on increasing the methane yield from manure, and especially of its solid fraction which is not so easily degradable. In the present study, Aqueous Ammonia Soaking (AAS) in six different concentrations in ammonia (5%, 10%, 15%, 20%, 25% and 32%) and for 1, 3 and 5 days...... at 22°C was applied on digested fibers separated from the effluent of a manure-fed, full-scale anaerobic digester. A methane yield increase from 76% to 104% was achieved during the first series of experiments, while the difference in reagent concentration did not considerably affect the methane yield...... is a very promising treatment resulting to an overall increase of the methane yield of digested manure fibers from 76 to 265% depending on the conditions and the batch of digested fibers used (an even higher increase of 190-265% was achieved during the 2nd series of experiments, where different AAS...

Impact of mechanical, chemical and enzymatic pre-treatments on the methane yield from the anaerobic digestion of switchgrass

International Nuclear Information System (INIS)

Frigon, Jean-Claude; Mehta, Punita; Guiot, Serge R.

2012-01-01

The conversion of cellulosic crops into biofuels, including methane, is receiving a lot of attention lately. Panicum vergatum, or switchgrass, is a warm season perennial grass well adapted to grow in North America. Different pre-treatments were tested in 0.5 l batch reactors, at 35 °C, in order to enhance the methane production from switchgrass, including temperature, sonication, alkalinization and autoclaving. The methane production on the basis of volatile solids (VS) added to the fermentation were 112.4 ± 8.4, 132.5 ± 9.7 and 139.8 ml g −1 after 38 days of incubation for winter harvested switchgrass (WHS) after grinding, grinding with alkalinization, and grinding with alkalinization and autoclaving, respectively. The methane production was higher for fresh summer harvested switchgrass (SHS), with a production of 256.6 ± 8.2 ml g −1 VS after mulching, alkalinization and autoclaving. The methane production from SHS was improved by 29 and 42% when applying lignin (LiP) or manganese peroxidase (MnP), at 202.1 ± 9.8 and 222.9 ± 22.5 ml g −1 VS, respectively. The combination of an alkali pre-treatment with the MnP increased the methane production furthermore at 297.7 ml g −1 VS. The use of pectinases without chemical pre-treatment showed promising yields at 287.4 and 239.5 ml g −1 VS for pectate-lyase and poly-galacturonase, respectively. An estimation of the methane yield per hectare of crop harvested resulted in net energy production of 29.8, 49.7 and 78.1 GJ for winter harvested switchgrass, mulched and pretreated summer harvested switchgrass, respectively. Switchgrass represents an interesting candidate as a lignocellulosic crop for methane production. -- Highlights: ► Switchgrass is a model energy crops for biofuels production. ► This study evaluated different pre-treatments to enhance methane production. ► Pre-treatments increase significantly the methane produced from switchgrass. ► Enzymatic pre-treatments were superior to physical and

Effects of sludge inoculum and organic feedstock on active microbial communities and methane yield during anaerobic digestion

Directory of Open Access Journals (Sweden)

David eWilkins

2015-10-01

Full Text Available Anaerobic digestion (AD is a widespread microbial technology used to treat organic waste and recover energy in the form of methane (biogas. While most AD systems have been designed to treat a single input, mixtures of digester sludge and solid organic waste are emerging as a means to improve efficiency and methane yield. We examined laboratory anaerobic cultures of AD sludge from two sources amended with food waste, xylose, and xylan at mesophilic temperatures, and with cellulose at meso- and thermophilic temperatures, to determine whether and how the inoculum and substrate affect biogas yield and community composition. All substrate and inoculum combinations yielded methane, with food waste most productive by mass. Pyrosequencing of transcribed bacterial and archaeal 16S rRNA showed that community composition varied across substrates and inocula, with differing ratios of hydrogenotrophic/acetoclastic methanogenic archaea associated with syntrophic partners. While communities did not cluster by either inoculum or substrate, additional sequencing of the bacterial 16S rRNA gene in the source sludge revealed that the bacterial communities were influenced by their inoculum. These results suggest that complete and efficient AD systems could potentially be assembled from different microbial inocula and consist of taxonomically diverse communities that nevertheless perform similar functions.

Dual characteristics of yield and ultimate strength as applied to two grades of beryllium

International Nuclear Information System (INIS)

Priddy, T.G.; Benzley, S.E.; Johnson, R.L.

1977-02-01

Published yield and ultimate biaxial strength data for two grades of beryllium are correlated with the use of a macroscopic failure model. Cross sections of the resulting surfaces in three-dimensional stress space are drawn to illustrate the expected transition from ductile to brittle fracture for triaxial tension states of stress. The usefulness of these models to the prediction of fracture in ductile materials is discussed. 5 tables, 8 figures, 11 references

Syntrophic microbial communities on straw as biofilm carrier increase the methane yield of a biowaste-digesting biogas reactor

Directory of Open Access Journals (Sweden)

Frank R. Bengelsdorf

2015-08-01

Full Text Available Biogas from biowaste can be an important source of renewable energy, but the fermentation process of low-structure waste is often unstable. The present study uses a full-scale biogas reactor to test the hypothesis that straw as an additional biofilm carrier will increase methane yield; and this effect is mirrored in a specific microbial community attached to the straw. Better reactor performance after addition of straw, at simultaneously higher organic loading rate and specific methane yield confirmed the hypothesis. The microbial communities on straw as a biofilm carrier and of the liquid reactor content were investigated using 16S rDNA amplicon sequencing by means of 454 pyrosequencing technology. The results revealed high diversity of the bacterial communities in the liquid reactor content as well as the biofilms on the straw. The most abundant archaea in all samples belonged to the genera Methanoculleus and Methanosarcina. Addition of straw resulted in a significantly different microbial community attached to the biofilm carrier. The bacterium Candidatus Cloacamonas acidaminovorans and methanogenic archaea of the genus Methanoculleus dominated the biofilm on straw. Syntrophic interactions between the hydrogenotrophic Methanoculleus sp. and members of the hydrogen-producing bacterial community within biofilms may explain the improved methane yield. Thus, straw addition can be used to improve and to stabilize the anaerobic process in substrates lacking biofilm-supporting structures.

Determination of the ultimate load in concrete slabs by the yield line finite element method

International Nuclear Information System (INIS)

Vaz, L.E.; Feijo, B.; Martha, L.F.R.; Lopes, M.M.

1984-01-01

A method for calculating the ultimate load in reinforced concrete slabs is proposed. The method follows the finite element aproach representating the continuum slab as an assembly of rigid triangular plates connected along their sides through yield line elements. This approach leads to the definition of the displacement configuration of the plate only as a function of the transversal displacement at the nodes of the mesh (1 DOF per node) reducing significantly the number of DOF's in relation to the conventional formulation by means of the finite element method (minimum of 3 DOF per node). Nonlinear behaviour of the reinforced concrete section is considered in the definition of the moment rotation curve of the yield lines. The effect of the in plane forces acting in the middle surface of the plate is also taken into account. The validity of the model is verified comparing the numerical solutions with the results of the classical yield line theory. (Author) [pt

A new method for the simultaneous enhancement of methane yield and reduction of hydrogen sulfide production in the anaerobic digestion of waste activated sludge.

Science.gov (United States)

Dai, Xiaohu; Hu, Chongliang; Zhang, Dong; Chen, Yinguang

2017-11-01

The biogas generated from anaerobic digestion (AD) also includes undesirable by-product such as hydrogen sulfide (H 2 S), which must be removed before the biogas can be used as a clean energy source. Therefore, it is necessary to find an appropriate strategy to simultaneously enhance the methane yield and reduce H 2 S production. An efficient strategy-pretreating sludge at pH 10 for 8d and adjusting the system at neutral pH to produce methane for 20d-is reported for the synchronous enhancement of methane production and reduction of H 2 S production during AD. The experimental results showed that the cumulative methane yield was 861.2±6.1mL/g volatile solids (VS) of sludge pretreated at pH 10 in semi-continuous stirred anaerobic reactors for 84d, an increase of 49.6% over the yield in the control. Meanwhile, the cumulative production of H 2 S was 144.1×10 -4 mL/g VS, 54.2% lower than that in the control. Copyright © 2017 Elsevier Ltd. All rights reserved.

Enhanced methane yield by co-digestion of sewage sludge with micro-algae and catering waste leachate.

Science.gov (United States)

2018-04-04

The co-digestion of different wastes is a promising concept to improve methane generation during anaerobic process. However, the anaerobic co-digestion of catering waste leachate with algal biomass and sewage sludge has not been studied to date. This work investigated the methane generation by the anaerobic co-digestion of different mixtures of catering waste leachate, micro-algal biomass, and sewage sludge. Co-digestion of waste mixture containing equal ratios of three substrates had 39.31% higher methane yield than anaerobic digestion of raw sludge. This was possibly due to a proliferation of methanogens during the co-digestion period induced by multi-phase digestion of different wastes with different degrees of digestibility. Therefore, co-digestion of catering waste leachate, micro-algal biomass, and sewage sludge appears to be an efficient technology for energy conversion from waste resources. The scientific application of this co-digestion technology with these three substrates may play a role in solving important environmental issues of waste management.

Biomass estimates, characteristics, biochemical methane potential, kinetics and energy flow from Jatropha curcus on dry lands

Energy Technology Data Exchange (ETDEWEB)

Nallathambi Gunaseelan, V. [Department of Zoology, PSG College of Arts and Science, Coimbatore 641 014 (India)

2009-04-15

In this study, we examined the production of Jatropha curcus plants on 1 ha of rain fed dry lands. All of the plant components that would result from plantation tending, fruit harvesting and processing were sampled for their yield and chemical composition, and then subjected to the biochemical methane potential (BMP) assay. The component parts exhibited significant variation in BMP which was reflected in their ultimate methane yield which ranged from 0.08 to 0.97 L g{sup -1} VS added, and their first order kinetics which ranged from 0.07 to 0.14 d{sup -1}. We examined two integrated utilization schemes: the first which converted plant prunings, fruit hulls and de-oiled seed cake to methane, and the oil to fatty acid methyl-ester (FAME); the second was to convert the seeds, plant prunings and fruit hulls entirely to methane. The basis for the plantation was, a density of 4444 plant ha{sup -1} (1.5 m x 1.5 m spacing), with a seed yield of 0.911 kg TS plant{sup -1} (1 kg total weight) with an oil content of 35% providing an annual oil yield of 1.42 t y{sup -1}. The corresponding yields of pruned leaves, fruit hulls and de-oiled cake are 0.97, 1.0, and 2.35 t VS ha y{sup -1}, respectively. An integrated scheme of producing biogas by means of anaerobic digestion of the latter components and oil for biodiesel would produce 90 GJ ha{sup -1} y{sup -1} in total with the oil being 54 GJ. The alternative biogas only option which would convert the seed oil into methane instead of biodiesel would produce 97 GJ ha{sup -1} y{sup -1}. (author)

The effects of digestion temperature and temperature shock on the biogas yields from the mesophilic anaerobic digestion of swine manure.

Science.gov (United States)

Chae, K J; Jang, Am; Yim, S K; Kim, In S

2008-01-01

In order to obtain basic design criteria for anaerobic digesters of swine manure, the effects of different digesting temperatures, temperature shocks and feed loads, on the biogas yields and methane content were evaluated. The digester temperatures were set at 25, 30 and 35 degrees C, with four feed loads of 5%, 10%, 20% and 40% (feed volume/digester volume). At a temperature of 30 degrees C, the methane yield was reduced by only 3% compared to 35 degrees C, while a 17.4% reduction was observed when the digestion was performed at 25 degrees C. Ultimate methane yields of 327, 389 and 403 mL CH(4)/g VS(added) were obtained at 25, 30 and 35 degrees C, respectively; with moderate feed loads from 5% to 20% (V/V). From the elemental analysis of swine manure, the theoretical biogas and methane yields at standard temperature and pressure were 1.12L biogas/g VS(destroyed) and 0.724 L CH(4)/g VS(destroyed), respectively. Also, the methane content increased with increasing digestion temperatures, but only to a small degree. Temperature shocks from 35 to 30 degrees C and again from 30 to 32 degrees C led to a decrease in the biogas production rate, but it rapidly resumed the value of the control reactor. In addition, no lasting damage was observed for the digestion performance, once it had recovered.

The distribution of methane in groundwater in Alberta (Canada) and associated aqueous geochemistry conditions

Science.gov (United States)

Humez, Pauline; Mayer, Bernhard; Nightingale, Michael; Becker, Veith; Kingston, Andrew; Taylor, Stephen; Millot, Romain; Kloppmann, Wolfram

2016-04-01

Development of unconventional energy resources such as shale gas and coalbed methane has generated some public concern with regard to the protection of groundwater and surface water resources from leakage of stray gas from the deep subsurface. In terms of environmental impact to and risk assessment of shallow groundwater resources, the ultimate challenge is to distinguish: (a) natural in-situ production of biogenic methane, (b) biogenic or thermogenic methane migration into shallow aquifers due to natural causes, and (c) thermogenic methane migration from deep sources due to human activities associated with the exploitation of conventional or unconventional oil and gas resources. We have conducted a NSERC-ANR co-funded baseline study investigating the occurrence of methane in shallow groundwater of Alberta (Canada), a province with a long record of conventional and unconventional hydrocarbon exploration. Our objective was to assess the occurrence and sources of methane in shallow groundwaters and to also characterize the hydrochemical environment in which the methane was formed or transformed through redox processes. Ultimately our aim was to determine whether methane was formed in-situ or whether it migrated from deeper formations into shallow aquifers. Combining hydrochemical and dissolved and free geochemical gas data from 372 groundwater samples obtained from 186 monitoring wells of the provincial groundwater observation well network (GOWN) in Alberta, it was found that methane is ubiquitous in groundwater in Alberta and is predominantly of biogenic origin. The highest concentrations of dissolved biogenic methane (> 0.01 mM or > 0.2 mg/L), characterized by δ13CCH4 values deep thermogenic gas that had migrated in significant amounts into shallow aquifers either naturally or via anthropogenically induced pathways. This study shows that the combined interpretation of aqueous geochemistry data in concert with the chemical and isotopic composition of dissolved and

Methane production from acid hydrolysates of Agave tequilana bagasse: evaluation of hydrolysis conditions and methane yield.

Science.gov (United States)

Arreola-Vargas, Jorge; Ojeda-Castillo, Valeria; Snell-Castro, Raúl; Corona-González, Rosa Isela; Alatriste-Mondragón, Felipe; Méndez-Acosta, Hugo O

2015-04-01

Evaluation of diluted acid hydrolysis for sugar extraction from cooked and uncooked Agave tequilana bagasse and feasibility of using the hydrolysates as substrate for methane production, with and without nutrient addition, in anaerobic sequencing batch reactors (AnSBR) were studied. Results showed that the hydrolysis over the cooked bagasse was more effective for sugar extraction at the studied conditions. Total sugars concentration in the cooked and uncooked bagasse hydrolysates were 27.9 g/L and 18.7 g/L, respectively. However, 5-hydroxymethylfurfural was detected in the cooked bagasse hydrolysate, and therefore, the uncooked bagasse hydrolysate was selected as substrate for methane production. Interestingly, results showed that the AnSBR operated without nutrient addition obtained a constant methane production (0.26 L CH4/g COD), whereas the AnSBR operated with nutrient addition presented a gradual methane suppression. Molecular analyses suggested that methane suppression in the experiment with nutrient addition was due to a negative effect over the archaeal/bacterial ratio. Copyright © 2015. Published by Elsevier Ltd.

Assessment of process control parameters in the biochemical methane potential of sunflower oil cake

International Nuclear Information System (INIS)

Raposo, F.; Borja, R.; Rincon, B.; Jimenez, A.M.

2008-01-01

A laboratory-scale study was conducted on the batch anaerobic digestion of sunflower oil cake (SuOC), solid waste derived from the extraction process of sunflower oil. A multi-reactor system was used to compare methane production from this waste at inoculum to substrate ratios (ISRs) of 3.0, 2.0, 1.5, 1.0, 0.8 and 0.5 (expressed as volatile solids (VS) basis). The tests were carried out at mesophilic temperature (35 deg. C) and run against a control of inoculum without substrate. The results obtained in the biochemical methane potential (BMP) tests showed that the ultimate methane yield (Y M,ult ) decreased considerably from 227±23 to 107±11 ml CH 4 at standard temperature and pressure (STP) conditions g -1 VS added when the ISR decreased from 3.0 to 0.5, showing a clear influence of the ISR on the methane yield coefficient. The biodegradability (BD) of the waste also decreased from 86% to 41% when the ISR varied from 3.0 to 0.5. A net total ammonia nitrogen (TAN) yield of 39.2 mg N g -1 VS added was obtained, and this value was not influenced by the ISRs assayed, which demonstrated the appropriate operation of the hydrolytic-acidogenic stage of the overall digestion process. A clear imbalance of the methanogenic process was observed at the lowest ISRs studied (0.5 and 0.8) due to a considerable increase in CODs and TVFA in the digestates. The profile of VFA was also influenced by the ISR, typical of the proteinaceous substrates

Formation temperatures of thermogenic and biogenic methane

Science.gov (United States)

Stolper, D.A.; Lawson, M.; Davis, C.L.; Ferreira, A.A.; Santos Neto, E. V.; Ellis, G.S.; Lewan, M.D.; Martini, Anna M.; Tang, Y.; Schoell, M.; Sessions, A.L.; Eiler, J.M.

2014-01-01

Methane is an important greenhouse gas and energy resource generated dominantly by methanogens at low temperatures and through the breakdown of organic molecules at high temperatures. However, methane-formation temperatures in nature are often poorly constrained. We measured formation temperatures of thermogenic and biogenic methane using a “clumped isotope” technique. Thermogenic gases yield formation temperatures between 157° and 221°C, within the nominal gas window, and biogenic gases yield formation temperatures consistent with their comparatively lower-temperature formational environments (<50°C). In systems where gases have migrated and other proxies for gas-generation temperature yield ambiguous results, methane clumped-isotope temperatures distinguish among and allow for independent tests of possible gas-formation models.

Reaction of methane with coal

Energy Technology Data Exchange (ETDEWEB)

Yang, K.; Batts, B.D.; Wilson, M.A.; Gorbaty, M.L.; Maa, P.S.; Long, M.A.; He, S.J.X.; Attala, M.I. [Macquarie University, Macquarie, NSW (Australia). School of Chemistry

1997-10-01

A study of the reactivities of Australian coals and one American coal with methane or methane-hydrogen mixtures, in the range 350-400{degree}C and a range of pressures (6.0-8.3 MPa, cold) is reported. The effects of aluminophosphates (AIPO) or zeolite catalysts, with and without exchanged metals, on reactivity have also been examined. Yields of dichloromethane extractable material are increased by using a methane rather than a nitrogen atmosphere and different catalysts assist dissolution to various extends. It appears that surface exchanged catalysts are effective, but incorporating metals during AIPO lattice formation is detrimental. Aluminium phosphate catalysts are unstable to water produced during coal conversion, but are still able to increase extraction yields. For the American coal, under methane-hydrogen and a copper exchanged zeolite, 51.5% conversion was obtained, with a product selectivity close to that obtained under hydrogen alone, and with only 2% hydrogen consumption. The conversion under methane-hydrogen was also to that obtained under hydrogen alone, while a linear dependence of conversion on proportion of methane would predict a 43% conversion under methane-hydrogen. This illustrates a synergistic effect of the methane-hydrogen atmosphere for coal liquefaction using this catalyst systems. 31 refs., 5 figs., 7 tabs.

Pretreatment of wheat straw for fermentation to methane

International Nuclear Information System (INIS)

Hashimoto, A.G.

1986-01-01

The effects of pretreating wheat straw with gamma-ray irradiation, ammonium hydroxide, and sodium hydroxide on methane yield, fermentation rate constant, and loss of feedstock constituents were evaluated using laboratory-scale batch fermentors. Results showed that methane yield increased as pretreatment alkali concentration increased, with the highest yield being 37% over untreated straw for the pretreatment consisting of sodium hydroxide dosage of 34 g OH - /kg volatile solids, at 90 0 C for 1 h. Gamma-ray irradiation had no significant effect on methane yield. Alkaline pretreatment temperatures above 100 0 C caused a decrease in methane yield. After more than 100 days of fermentation, all of the hemicellulose and more than 80% of the cellulose were degraded. The loss in cellulose and hemicellulose accounted for 100% of the volatile solids lost. No consistent effect of pretreatments on batch fermentation rates was noted. Semicontinuous fermentations of straw-manure mixtures confirmed the relative effectiveness of sodium- and ammonium-hydroxide pretreatments

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)

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

Light-Dependent Aerobic Methane Oxidation Reduces Methane Emissions from Seasonally Stratified Lakes

Science.gov (United States)

Oswald, Kirsten; Milucka, Jana; Brand, Andreas; Littmann, Sten; Wehrli, Bernhard; Kuypers, Marcel M. M.; Schubert, Carsten J.

2015-01-01

Lakes are a natural source of methane to the atmosphere and contribute significantly to total emissions compared to the oceans. Controls on methane emissions from lake surfaces, particularly biotic processes within anoxic hypolimnia, are only partially understood. Here we investigated biological methane oxidation in the water column of the seasonally stratified Lake Rotsee. A zone of methane oxidation extending from the oxic/anoxic interface into anoxic waters was identified by chemical profiling of oxygen, methane and δ13C of methane. Incubation experiments with 13C-methane yielded highest oxidation rates within the oxycline, and comparable rates were measured in anoxic waters. Despite predominantly anoxic conditions within the zone of methane oxidation, known groups of anaerobic methanotrophic archaea were conspicuously absent. Instead, aerobic gammaproteobacterial methanotrophs were identified as the active methane oxidizers. In addition, continuous oxidation and maximum rates always occurred under light conditions. These findings, along with the detection of chlorophyll a, suggest that aerobic methane oxidation is tightly coupled to light-dependent photosynthetic oxygen production both at the oxycline and in the anoxic bottom layer. It is likely that this interaction between oxygenic phototrophs and aerobic methanotrophs represents a widespread mechanism by which methane is oxidized in lake water, thus diminishing its release into the atmosphere. PMID:26193458

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

Utilization of coalbed methane

Energy Technology Data Exchange (ETDEWEB)

Gustavson, J.B. [Gustavson Associates Inc., Boulder, CO (United States)

1996-02-01

Substantial progress has been made in capturing coalbed methane (CBM gas), which constitutes a valuable source of clean burning energy. It is of importance to study the various potential uses of coalbed methane and to understand the various technologies required, as well as their economics and any institutional constraints. In industrialised countries, the uses of coalbed methane are almost solely dependent on microeconomics; coalbed methane must compete for a market against natural gas and other energy sources - and frequently, coalbed methane is not competitive against other energy sources. In developing countries, on the other hand, particularly where other sources of energy are in short supply, coalbed methane economics yield positive results. Here, constraints to development of CBM utilization are mainly lack of technology and investment capital. Sociological aspects such as attitude and cultural habits, may also have a strong negative influence. This paper outlines the economics of coalbed methane utilization, particularly its competition with natural gas, and touches upon the many different uses to which coalbed methane may be applied. 24 refs., 4 figs.

Ultimate load capacity assessment of reinforced concrete shell structures

International Nuclear Information System (INIS)

Gupta, Amita; Singh, R.K.; Kushwaha, H.S.; Mahajan, S.C.; Kakodkar, A.

1993-01-01

The objective of this study is to develop capability for prediction of ultimate load capacity of reinforced concrete shell structures. The present finite element code ULCA (Ultimate Load Capacity Assessment) adopts a degenerate concept of formulating general isoparametric shell element with a layered approach in the thickness direction. Different failure modes such as crushing, tensile cracking and reinforcement yielding are recognised for various problems. The structure fails by crushing of concrete when the concrete strain/stress reaches the ultimate stress or strain of concrete. Material nonlinearities as a result of tension cracking, tension stiffening between reinforcement and concrete in cracked region and yielding of reinforcement are considered along with geometric nonlinearity. Thus with this code it is possible to predict the pressure at which the first cracking, first through thickness cracking, first yielding of reinforcement occurs. After validating the code with few bench mark problems for different failure modes a reinforced concrete nuclear containment is analysed for its ultimate capacity and the results are matched with the published results. Further the ultimate load capacity of outer containment wall of Narora Atomic Power Station is predicted. It is observed that containment fails in membrane region and has a sufficient margin against design pressure. (author). 9 refs., 56 figs., 3 tabs., 1 appendix with 4 tabs

Thermophilic anaerobic co-digestion of sewage sludge with grease waste: Effect of long chain fatty acids in the methane yield and its dewatering properties

International Nuclear Information System (INIS)

Silvestre, G.; Illa, J.; Fernández, B.; Bonmatí, A.

2014-01-01

Highlights: • Thermophilic anaerobic codigestion of sewage sludge and grease waste (GW) doubles methane yield. • High GW doses in the influent leads to instability and LCFA accumulation in the effluent. • GW addition promotes acetoclastic activity whilst worsening the hydrogenothrophic activity. • The mesophilic codigestion with GW performs better than the thermophilic one. - Abstract: Thermophilic co-digestion of sewage sludge with three different doses of trapped grease waste (GW) from the pre-treatment of a WWTP has been assessed in a CSTR bench-scale reactor. After adding 12% and 27% of grease waste (on COD basis), the organic loading rate increased from 2.2 to 2.3 and 2.8 kg COD m −3 d −1 respectively, and the methane yield increased 1.2 and 2.2 times. Further GW increase (37% on COD basis) resulted in an unstable methane yield and in long chain fatty acids (LCFA) accumulation. Although this inestability, the presence of volatile fatty acids in the effluent was negligible, showing good adaptation to fats of the thermophilic biomass. Nevertheless, the presence of LCFA in the effluent worsens its dewatering properties. Specific methanogenic activity tests showed that the addition of grease waste ameliorates the acetoclastic activity in detriment of the hydrogenotrophic activity, and suggests that the tolerance to LCFA can be further enhanced by slowly increasing the addition of lipid-rich materials

Optimizing feeding composition and carbon-nitrogen ratios for improved methane yield during anaerobic co-digestion of dairy, chicken manure and wheat straw.

Science.gov (United States)

Wang, Xiaojiao; Yang, Gaihe; Feng, Yongzhong; Ren, Guangxin; Han, Xinhui

2012-09-01

This study investigated the possibilities of improving methane yield from anaerobic digestion of multi-component substrates, using a mixture of dairy manure (DM), chicken manure (CM) and wheat straw (WS), based on optimized feeding composition and the C/N ratio. Co-digestion of DM, CM and WS performed better in methane potential than individual digestion. A larger synergetic effect in co-digestion of DM, CM and WS was found than in mixtures of single manures with WS. As the C/N ratio increased, methane potential initially increased and then declined. C/N ratios of 25:1 and 30:1 had better digestion performance with stable pH and low concentrations of total ammonium nitrogen and free NH(3). Maximum methane potential was achieved with DM/CM of 40.3:59.7 and a C/N ratio of 27.2:1 after optimization using response surface methodology. The results suggested that better performance of anaerobic co-digestion can be fulfilled by optimizing feeding composition and the C/N ratio. Copyright © 2012 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)

Carbohydrate-enriched cyanobacterial biomass as feedstock for bio-methane production through anaerobic digestion

DEFF Research Database (Denmark)

Markou, Giorgos; Angelidaki, Irini; Georgakakis, Dimitris

2013-01-01

The anaerobic digestion performance using carbohydrate-enriched biomass of Arthrospira platensis was studied. The carbohydrate enrichment was achieved after the cultivation of A. platensis under phosphorus limitation conditions. Three biomass compositions (60%, 40% and 20% carbohydrates content......) were used. The overall observation as the biomass carbohydrates increased was that bio-methane yield increased. The highest bio-methane yield in bioreactors with 60% carbohydrates was 203±10ml CH4 gCODinfl-1, while the lowest bio-methane yield in bioreactors with 20% carbohydrates was 123±10ml CH4 g......CODinfl-1. The trend of increasing bio-methane yield as carbohydrates content of the biomass increased was observed almost in all three HRT (15, 20 and 30days) studied and after thermal pre-treatment. However, thermal pre-treatment did not improve the bio-methane yield. Ammonia concentration had an overall...

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.

Low ambient temperature elevates plasma triiodothyronine concentrations while reducing digesta mean retention time and methane yield in sheep.

Science.gov (United States)

Barnett, M C; McFarlane, J R; Hegarty, R S

2015-06-01

Ruminant methane yield (MY) is positively correlated with mean retention time (MRT) of digesta. The hormone triiodothyronine (T3 ), which is negatively correlated with ambient temperature, is known to influence MRT. It was hypothesised that exposing sheep to low ambient temperatures would increase plasma T3 concentration and decrease MRT of digesta within the rumen of sheep, resulting in a reduction of MY. To test this hypothesis, six Merino sheep were exposed to two different ambient temperatures (cold treatment, 9 ± 1 °C; warm control 26 ± 1 °C). The effects on MY, digesta MRT, plasma T3 concentration, CO2 production, DM intake, DM digestibility, change in body weight (BW), rumen volatile fatty acid (VFA) concentrations, estimated microbial protein output, protozoa abundance, wool growth, water intake, urine output and rectal temperature were studied. Cold treatment resulted in a reduction in MY (p < 0.01); digesta MRT in rumen (p < 0.01), hindgut (p = 0.01) and total digestive tract (p < 0.01); protozoa abundance (p < 0.05); and water intake (p < 0.001). Exposure to cold temperature increased plasma T3 concentration (p < 0.05), CO2 production (p = 0.01), total VFA concentrations (p = 0.03) and estimated microbial output from the rumen (p = 0.03). The rate of wool growth increased (p < 0.01) due to cold treatment, but DM intake, DM digestibility and BW change were not affected. The results suggest that exposure of sheep to cold ambient temperatures reduces digesta retention time in the gastrointestinal tract, leading to a reduction in enteric methane yield. Further research is warranted to determine whether T3 could be used as an indirect selection tool for genetic selection of low enteric methane-producing ruminants. Journal of Animal Physiology and Animal Nutrition © 2014 Blackwell Verlag GmbH.

Ultimate internal pressure capacity of concrete containment structures

International Nuclear Information System (INIS)

Krishnaswamy, C.N.; Namperumal, R.; Al-Dabbagh, A.

1983-01-01

Lesson learned from the accident at Three-Mile Island nuclear plant has necessitated the computation of the ultimate internal pressure capacity of containment structures as a licensing requirement in the U.S. In general, a containment structure is designed to be essentially elastic under design accident pressure. However, as the containment pressure builds up beyond the design value due to a more severe postulated accident, the containment response turns nonlinear as it sequentially passes through cracking of concrete, yielding of linear plate, yielding of rebar, and yielding of post-tensioning tendon (if the containment concrete is prestressed). This paper reports on the determination of the ultimate internal pressure capacity and nonlinear behavior of typical reinforced and prestressed concrete BWR containments. The probable modes of failure, the criteria for ultimate pressure capacity, and the most critical sections are described. Simple equations to hand-calculate the ultimate pressure capacity and the nonlinear behavior at membrane sections of the containment shell are presented. A nonlinear finite element analysis performed to determine the nonlinear behavior of the entire shell including nonmembrane sections is briefly discribed. The analysis model consisted of laminated axisymmetric shell finite elements with nonlinear stress-strain properties for each material. Results presented for typical BWR concrete containments include nonlinear response plots of internal pressure versus containment deflection and strains in the liner, rebar, and post-tensioning tendons at the most stressed section in the shell. Leak-tightness of the containment liner and the effect of thermal loads on the ultimate capacity are discussed. (orig.)

Mass loss controlled thermal pretreatment system to assess the effects of pretreatment temperature on organic matter solubilization and methane yield from food waste.

Directory of Open Access Journals (Sweden)

Martha Minale Yeshanew

2016-09-01

Full Text Available The effects of thermal pretreatment (TP on the main characteristics of food waste (FW and its biochemical methane potential (BMP and distribution of volatile fatty acids (VFAs under mesophilic condition (35 ⁰C were investigated. The TP experiments were carried out at 80 °C, 100 °C, 120 °C for 2 hour and 140 °C for 1 hour. The designed TP set-up was able to minimize the organic matter loss during the course of the pretreatments. Soluble organic fractions evaluated in terms of chemical oxygen demand (COD and soluble protein increased linearly with pretreatment temperature. In contrast, the carbohydrate solubilization was more enhanced (30 % higher solubilization by the TP at lower temperature (80 °C. A slight increment of soluble phenols was found, particularly for temperatures exceeding 100 °C. Thermally pretreated FW under all conditions exhibited an improved methane yield than the untreated FW, due to the increased organic matter solubilization. The highest cumulative methane yield of 442 (± 8.6 mL/gVSadded, corresponding to a 28.1 % enhancement compared to the untreated FW, was obtained with a TP at 80 °C. No significant variation in the VFAs trends were observed during the BMP tests under all investigated conditions.

Experimental study of methanic fermentation of straw

Energy Technology Data Exchange (ETDEWEB)

Dopter, P; Beerens, H

1952-12-03

The amount of liquid manure obtainable was a limiting factor in methanic fermentation of wheat straw. An equal volume of 0.2% aqueous solution of Na formate could be substituted for 90% of the normal requirements of liquid manure. This shortened the preliminary stages of cellulosic fermentation when no methane was produced and slightly increased the subsequent yield of methane.

Recent advances in methane activation

Energy Technology Data Exchange (ETDEWEB)

Huuska, M; Kataja, K [VTT Chemical Technology, Espoo (Finland)

1997-12-31

Considerable work has been done in the research and development of methane conversion technologies. Although some promising conversion processes have been demonstrated, further advances in engineering and also in the chemistry are needed before these technologies become commercial. High-temperature processes, e.g. the oxidative coupling of methane, studied thoroughly during the last 15 years, suffer from severe theoretical yield limits and poor economics. In the long term, the most promising approaches seem to be the organometallic and, especially, the biomimetic activation of methane. (author) (22 refs.)

Recent advances in methane activation

Energy Technology Data Exchange (ETDEWEB)

Huuska, M.; Kataja, K. [VTT Chemical Technology, Espoo (Finland)

1996-12-31

Considerable work has been done in the research and development of methane conversion technologies. Although some promising conversion processes have been demonstrated, further advances in engineering and also in the chemistry are needed before these technologies become commercial. High-temperature processes, e.g. the oxidative coupling of methane, studied thoroughly during the last 15 years, suffer from severe theoretical yield limits and poor economics. In the long term, the most promising approaches seem to be the organometallic and, especially, the biomimetic activation of methane. (author) (22 refs.)

Combined gas-phase oxidation of methane and ethylene

International Nuclear Information System (INIS)

Pogosyan, N.M.; Pogosyan, M.D.

2009-01-01

It is established that depending on the reaction conditions combined oxidation of methane and ethylene may result in ethylene and propylene oxides with high selectivity with respect to the process, where in the initial reaction mixture methane is replaced by the same quantity of nitrogen. The formed additional methyl radicals increase the yield of all reaction products except CO. At low temperatures methyl radicals react with oxygen resulting in methyl peroxide radicals, which in turn, reacting with ethylene provide its epoxidation and formation of other oxygen-containing products. At high temperatures as a result of addition reaction between methyl radicals and ethylene, propyl radicals are formed that, in turn yield propylene. Alongside with positive influence on the yield of reaction products, methane exerts negative influence upon the conversion, that is it decreases the rate of ethylene and oxygen conversion, simultaneously decreasing significantly the yield of CO

Vegetable processing wastes addition to improve swine manure anaerobic digestion: Evaluation in terms of methane yield and SEM characterization

International Nuclear Information System (INIS)

Molinuevo-Salces, Beatriz; González-Fernández, Cristina; Gómez, Xiomar; García-González, María Cruz; Morán, Antonio

2012-01-01

Highlights: ► Vegetable waste as co-substrate for swine manure anaerobic digestion. ► Two hydraulic retention times of 25 and 15 d, respectively. ► SEM characterization of anaerobic sludges to observe microbial composition. ► Vegetable waste as co-substrate increases methane yields up to three times. ► Microbial composition changes after 120 d of digestion. -- Abstract: The effect of adding vegetable waste as a co-substrate in the anaerobic digestion of swine manure was investigated. The study was carried out at laboratory scale using semi-continuous stirred tank reactors working at 37 °C. Organic loading rates (OLRs) of 0.4 and 0.6 g VS L −1 d −1 were evaluated, corresponding to hydraulic retention times (HRTs) of 25 and 15 d, respectively. The addition of vegetable wastes (50% dw/dw) resulted in an improvement of 3 and 1.4-fold in methane yields at HRTs of 25 and 15 d, respectively. Changes on microbial morphotypes were studied by Scanning Electron Microscopy (SEM). Samples analyzed were sludge used as inoculum and digestate obtained from swine manure anaerobic reactors. SEM pictures demonstrated that lignocellulosic material was not completely degraded. Additionally, microbial composition was found to change to cocci and rods morphotypes after 120 d of anaerobic digestion.

Biogas production from high-yielding energy crops in boreal conditions

Energy Technology Data Exchange (ETDEWEB)

Seppala, M.

2013-11-01

In this thesis, the methane production potential of traditional and novel energy crops was evaluated in boreal conditions. The highest methane yield per hectare was achieved with maize (4 000-9 200 m{sup 3}CH{sub 4} ha{sup -1} a{sup -1}) and the second highest with brown knapweed (2 700-6 100 m{sup 3}CH{sub 4} ha{sup -1} a{sup -1}). Recently, the most feasible energy crop, grass, produced 1 200-3 600 m{sup 3}CH{sub 4} ha{sup -1} a{sup -1}. The specific methane yields of traditional and novel energy crops varied from 170-500 l kg{sup -1} volatile solid (VS). The highest specific methane yields were obtained with maize, while the novel energy crops were at a lower range. The specific methane yields decreased in the later harvest time with maize and brown knapweed, and the specific methane yield of the grasses decreased from the 1st to 2nd harvests. Maize and brown knapweed produced the highest total solid (TS) yields per hectare 13-23 tTS ha{sup -1}, which were high when compared with the TS yields of grasses (6-13 tTS ha{sup -1}). The feasibility of maize and brown knapweed in co-digestion with liquid cow manure, in continuously stirred tank reactors (CSTR), was evaluated. According to the CSTR runs, maize and brown knapweed are suitable feeds and have stable processes, producing the highest methane yields (organic loading rate 2 kgVS m{sup -3}d{sup -1}), with maize at 259 l kgVS{sup -1} and brown knapweed at 254 l kgVS{sup -1}. The energy balance (input/output) of the cultivation of the grasses, maize and brown knapweed was calculated in boreal conditions, and it was better when the digestate was used as a fertilizer (1.8-4.8 %) than using chemical fertilizers (3.7-16.2 %), whose production is the most energy demanding process in cultivation. In conclusion, the methane production of maize, grasses and novel energy crops can produce high methane yields and are suitable feeds for anaerobic digestion. The cultivation managements of maize and novel energy crops for

Hydrogen production by methane reforming based on micro-gap discharge

International Nuclear Information System (INIS)

Liu, N N; Wang, M X; Liu, K Y; Bai, M D

2013-01-01

Based on micro-gap strong ionization discharge, this paper presents a study of hydrogen production by methane reforming at room temperature and atmospheric pressure without catalyst. Influence rules of conversion of methane and production of hydrogen were studied by changing discharge power and feed gas flow rate. Results show that when the discharge power was about 341 W, the discharge gap was 0.47 mm and the flow rate of feed gas was 100 mL min −1 , the conversion of methane and yield of hydrogen reached optimization. The conversion rate of methane and the highest yield of hydrogen were 68.14 % and 51.34 %, respectively.

Chemical composition and methane potential of commercial food wastes.

Science.gov (United States)

Lopez, Victoria M; De la Cruz, Florentino B; Barlaz, Morton A

2016-10-01

There is increasing interest in anaerobic digestion in the U.S. However, there is little information on the characterization of commercial food waste sources as well as the effect of waste particle size on methane yield. The objective of this research was to characterize four commercial food waste sources: (1) university dining hall waste, (2) waste resulting from prepared foods and leftover produce at a grocery store, (3) food waste from a hotel and convention center, and (4) food preparation waste from a restaurant. Each sample was tested in triplicate 8L batch anaerobic digesters after shredding and after shredding plus grinding. Average methane yields for the university dining, grocery store, hotel, and restaurant wastes were 363, 427, 492, and 403mL/dry g, respectively. Starch exhibited the most complete consumption and particle size did not significantly affect methane yields for any of the tested substrates. Lipids represented 59-70% of the methane potential of the fresh substrates. Copyright © 2016 Elsevier Ltd. All rights reserved.

Dry anaerobic co-digestion of food waste and cattle manure: Impact of total solids, substrate ratio and thermal pre treatment on methane yield and quality of biomanure.

Science.gov (United States)

Arelli, Vijayalakshmi; Begum, Sameena; Anupoju, Gangagni Rao; Kuruti, Kranti; S, Shailaja

2018-04-01

The objective of the present study is to assess the impact of TS concentration, substrate mixing ratio (co digestion) and thermal pretreatment on biogas production, methane yield, VS reduction (%) and quality of biomanure through dry anaerobic digestion (DAD) of food waste (FW) and cattle manure (CM). Results divulged that the optimum methane yield and biomanure of 0.18 and 0.21 m 3 CH 4 /(kg VS reduced) and 3.15 and 2.8 kg/kg waste was obtained from FW at TS of 25% and 30% at an HRT of 41 and 31 days respectively whereas it was 0.32 and 0.43 m 3 CH 4 /(kg VS reduced) and 2.2 and 1.15 kg/kg waste from pretreated FW at an HRT of 16 and 20 days correspondingly. Improvement of methane from 62 to 81% was obtained due to thermal pretreatment. The highest nutrient recovery in terms of N, P, K was found to be 5.14, 2.6 and 3.2 respectively. Copyright © 2018 Elsevier Ltd. All rights reserved.

Bioenergy potential of Ulva lactuca: Biomass yield, methane production and combustion

DEFF Research Database (Denmark)

Bruhn, Annette; Dahl, Jonas; Bangsø Nielsen, Henrik

2011-01-01

The biomass production potential at temperate latitudes (56°N), and the quality of the biomass for energy production (anaerobic digestion to methane and direct combustion) were investigated for the green macroalgae, Ulva lactuca. The algae were cultivated in a land based facility demonstrating...... in weight specific methane production compared to wet biomass. Ash and alkali contents are the main challenges in the use of U. lactuca for direct combustion. Application of a bio-refinery concept could increase the economical value of the U. lactuca biomass as well as improve its suitability for production...

Genomic heritabilities and genomic estimated breeding values for methane traits in Angus cattle.

Science.gov (United States)

Hayes, B J; Donoghue, K A; Reich, C M; Mason, B A; Bird-Gardiner, T; Herd, R M; Arthur, P F

2016-03-01

Enteric methane emissions from beef cattle are a significant component of total greenhouse gas emissions from agriculture. The variation between beef cattle in methane emissions is partly genetic, whether measured as methane production, methane yield (methane production/DMI), or residual methane production (observed methane production - expected methane production), with heritabilities ranging from 0.19 to 0.29. This suggests methane emissions could be reduced by selection. Given the high cost of measuring methane production from individual beef cattle, genomic selection is the most feasible approach to achieve this reduction in emissions. We derived genomic EBV (GEBV) for methane traits from a reference set of 747 Angus animals phenotyped for methane traits and genotyped for 630,000 SNP. The accuracy of GEBV was tested in a validation set of 273 Angus animals phenotyped for the same traits. Accuracies of GEBV ranged from 0.29 ± 0.06 for methane yield and 0.35 ± 0.06 for residual methane production. Selection on GEBV using the genomic prediction equations derived here could reduce emissions for Angus cattle by roughly 5% over 10 yr.

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)

Post-anaerobic digestion thermal hydrolysis of sewage sludge and food waste: Effect on methane yields, dewaterability and solids reduction.

Science.gov (United States)

Svensson, Kine; Kjørlaug, Oda; Higgins, Matthew J; Linjordet, Roar; Horn, Svein J

2018-04-01

Post-anaerobic digestion (PAD) treatment technologies have been suggested for anaerobic digestion (AD) to improve process efficiency and assure hygenization of organic waste. Because AD reduces the amount of organic waste, PAD can be applied to a much smaller volume of waste compared to pre-digestion treatment, thereby improving efficiency. In this study, dewatered digestate cakes from two different AD plants were thermally hydrolyzed and dewatered, and the liquid fraction was recirculated to a semi-continuous AD reactor. The thermal hydrolysis was more efficient in relation to methane yields and extent of dewaterability for the cake from a plant treating waste activated sludge, than the cake from a plant treating source separated food waste (SSFW). Temperatures above 165 °C yielded the best results. Post-treatment improved volumetric methane yields by 7% and the COD-reduction increased from 68% to 74% in a mesophilic (37 °C) semi-continuous system despite lowering the solid retention time (from 17 to 14 days) compared to a conventional system with pre-treatment of feed substrates at 70 °C. Results from thermogravimetric analysis showed an expected increase in maximum TS content of dewatered digestate cake from 34% up to 46% for the SSFW digestate cake, and from 17% up to 43% in the sludge digestate cake, after the PAD thermal hydrolysis process (PAD-THP). The increased dewatering alone accounts for a reduction in wet mass of cake leaving the plant of 60% in the case of sludge digestate cake. Additionaly, the increased VS-reduction will contribute to further reduce the mass of wet cake. Copyright © 2018 Elsevier Ltd. All rights reserved.

Building a better methane generation model: Validating models with methane recovery rates from 35 Canadian landfills.

Science.gov (United States)

Thompson, Shirley; Sawyer, Jennifer; Bonam, Rathan; Valdivia, J E

2009-07-01

The German EPER, TNO, Belgium, LandGEM, and Scholl Canyon models for estimating methane production were compared to methane recovery rates for 35 Canadian landfills, assuming that 20% of emissions were not recovered. Two different fractions of degradable organic carbon (DOC(f)) were applied in all models. Most models performed better when the DOC(f) was 0.5 compared to 0.77. The Belgium, Scholl Canyon, and LandGEM version 2.01 models produced the best results of the existing models with respective mean absolute errors compared to methane generation rates (recovery rates + 20%) of 91%, 71%, and 89% at 0.50 DOC(f) and 171%, 115%, and 81% at 0.77 DOC(f). The Scholl Canyon model typically overestimated methane recovery rates and the LandGEM version 2.01 model, which modifies the Scholl Canyon model by dividing waste by 10, consistently underestimated methane recovery rates; this comparison suggested that modifying the divisor for waste in the Scholl Canyon model between one and ten could improve its accuracy. At 0.50 DOC(f) and 0.77 DOC(f) the modified model had the lowest absolute mean error when divided by 1.5 yielding 63 +/- 45% and 2.3 yielding 57 +/- 47%, respectively. These modified models reduced error and variability substantially and both have a strong correlation of r = 0.92.

A laboratory study of anaerobic oxidation of methane in the presence of methane hydrate

Science.gov (United States)

Solem, R.; Bartlett, D.; Kastner, M.; Valentine, D.

2003-12-01

In order to mimic and study the process of anaerobic methane oxidation in methane hydrate regions we developed four high-pressure anaerobic bioreactors, designed to incubate environmental sediment samples, and enrich for populations of microbes associated with anaerobic methane oxidation (AMO). We obtained sediment inocula from a bacterial mat at the southern Hydrate Ridge, Cascadia, having cell counts approaching 1010 cells/cc. Ultimately, our goal is to produce an enriched culture of these microbes for characterization of the biochemical processes and chemical fluxes involved, as well as the unique adaptations required for, AMO. Molecular phylogenetic information along with results from fluorescent in situ hybridization indicate that consortia of Archaea and Bacteria are present which are related to those previously described for marine sediment AMO environments. Using a medium of enriched seawater and sediment in a 3:1 ratio, the system was incubated at 4° C under 43 atm of methane pressure; the temperature and pressure were kept constant. We have followed the reactions for seven months, particularly the vigorous consumption rates of dissolved sulfate and alkalinity production, as well as increases in HS-, and decreases in Ca concentrations. We also monitored the dissolved inorganic C (DIC) δ 13C values. The data were reproduced, and indicated that the process is extremely sensitive to changes in methane pressure. The rates of decrease in sulfate and increase in alkalinity concentrations were complimentary and showed considerable linearity with time. When the pressure in the reactor was decreased below the methane hydrate stability field, following the methane hydrate dissociation, sulfate reduction abruptly decreased. When the pressure was restored all the reactions returned to their previous rates. Much of the methane oxidation activity in the reactor is believed to occur in association with the methane hydrate. Upon the completion of one of the experiments

Kinetic Study of Nonequilibrium Plasma-Assisted Methane Steam Reforming

Directory of Open Access Journals (Sweden)

Hongtao Zheng

2014-01-01

Full Text Available To develop a detailed reaction mechanism for plasma-assisted methane steam reforming, a comprehensive numerical and experimental study of effect laws on methane conversion and products yield is performed at different steam to methane molar ratio (S/C, residence time s, and reaction temperatures. A CHEMKIN-PRO software with sensitivity analysis module and path flux analysis module was used for simulations. A set of comparisons show that the developed reaction mechanism can accurately predict methane conversion and the trend of products yield in different operating conditions. Using the developed reaction mechanism in plasma-assisted kinetic model, the reaction path flux analysis was carried out. The result shows that CH3 recombination is the limiting reaction for CO production and O is the critical species for CO production. Adding 40 wt.% Ni/SiO2 in discharge region has significantly promoted the yield of H2, CO, or CO2 in dielectric packed bed (DPB reactor. Plasma catalytic hybrid reforming experiment verifies the reaction path flux analysis tentatively.

The photochemical reaction of 1,1-dicyano-3-phenylbut-1-ene. Simultaneous occurrence of p-methane and di-p-methane rearrangements

Directory of Open Access Journals (Sweden)

Silva Francisco A. da

1999-01-01

Full Text Available The direct photolysis of 1,1-dicyano-3-phenylbut-1-ene (3-MDCN was investigated at room temperature in solvents of different polarities (hexane, dichloromethane and acetonitrile. Cyclopropanes arising from both the di-pi-methane and pi-methane (1,2-H migration processes were obtained as photoproducts. The structures of the products were elucidated by ¹H-NMR, GC/MS, IR and chromatography. Relative quantum yield determination and GC analysis of sequential irradiations gave evidence that: i no secondary reactions occur, even at high conversions; ii the di-pi-methane rearrangement is significantly more affected by the solvent variation than the pi-methane reaction. Photosensitization with acetophenone or acetone did not yield any observable products. The existence of the simultaneous mechanisms and the observed effects were considered as evidence of a possible differentiation between localized and delocalized excitation on the excited state surface.

Evidence for methane in Martian meteorites.

Science.gov (United States)

Blamey, Nigel J F; Parnell, John; McMahon, Sean; Mark, Darren F; Tomkinson, Tim; Lee, Martin; Shivak, Jared; Izawa, Matthew R M; Banerjee, Neil R; Flemming, Roberta L

2015-06-16

The putative occurrence of methane in the Martian atmosphere has had a major influence on the exploration of Mars, especially by the implication of active biology. The occurrence has not been borne out by measurements of atmosphere by the MSL rover Curiosity but, as on Earth, methane on Mars is most likely in the subsurface of the crust. Serpentinization of olivine-bearing rocks, to yield hydrogen that may further react with carbon-bearing species, has been widely invoked as a source of methane on Mars, but this possibility has not hitherto been tested. Here we show that some Martian meteorites, representing basic igneous rocks, liberate a methane-rich volatile component on crushing. The occurrence of methane in Martian rock samples adds strong weight to models whereby any life on Mars is/was likely to be resident in a subsurface habitat, where methane could be a source of energy and carbon for microbial activity.

Methane productivity of manure, straw and solid fractions of manure

DEFF Research Database (Denmark)

Møller, H.B.; Sommer, S.G.; Ahring, Birgitte Kiær

2004-01-01

are in the same range (282-301 m(3) CH4 LU-1). Pre-treatment of manure by separation is a way of making fractions of the manure that have a higher gas potential per volume. Theoretical methane potential and biodegradability of three types of fractions deriving from manure separation were tested. The volumetric...... methane yield of straw was found to be higher than the yield from total manure and the solid fractions of manure, due to the higher VS content, and hence the use of straw as bedding material will increase the volumetric as well as the livestock-based methane productivity....

Short communication: Genetic study of methane production predicted from milk fat composition in dairy cows.

Science.gov (United States)

van Engelen, S; Bovenhuis, H; Dijkstra, J; van Arendonk, J A M; Visker, M H P W

2015-11-01

Dairy cows produce enteric methane, a greenhouse gas with 25 times the global warming potential of CO2. Breeding could make a permanent, cumulative, and long-term contribution to methane reduction. Due to a lack of accurate, repeatable, individual methane measurements needed for breeding, indicators of methane production based on milk fatty acids have been proposed. The aim of the present study was to quantify the genetic variation for predicted methane yields. The milk fat composition of 1,905 first-lactation Dutch Holstein-Friesian cows was used to investigate 3 different predicted methane yields (g/kg of DMI): Methane1, Methane2, and Methane3. Methane1 was based on the milk fat proportions of C17:0anteiso, C18:1 rans-10+11, C18:1 cis-11, and C18:1 cis-13 (R(2)=0.73). Methane2 was based on C4:0, C18:0, C18:1 trans-10+11, and C18:1 cis-11 (R(2)=0.70). Methane3 was based on C4:0, C6:0, and C18:1 trans-10+11 (R(2)=0.63). Predicted methane yields were demonstrated to be heritable traits, with heritabilities between 0.12 and 0.44. Breeding can, thus, be used to decrease methane production predicted based on milk fatty acids. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

The effect of harvest time, dry matter content and mechanical pretreatments on anaerobic digestion and enzymatic hydrolysis of miscanthus

DEFF Research Database (Denmark)

Nielsen, Susanne Frydendal; Hjorth, Maibritt; Baby, Sanmohan

2016-01-01

-milling, extrusion or grinding and accumulated methane production and enzymatically-accessible sugars were measured. Accumulated methane production was studied using sigmoid curves that allowed comparison among the treatments of the rate of the methane production and ultimate methane yield. The green biomass gave...

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

Science.gov (United States)

Kim-Hak, D.; Fleck, D.

2017-12-01

Natural gas analysis and methane specifically have become increasingly important by virtue of methane's 28-36x greenhouse warming potential compared to CO2 and accounting for 10% of total greenhouse gas emissions in the US alone. Additionally, large uncontrolled leaks, such as the recent one from Aliso Canyon in Southern California, originating from uncapped wells, storage facilities and coal mines have increased the total global contribution of methane missions even further. Determining the specific fingerprint of methane sources by quantifying the ethane to methane (C2:C1) ratios provides us with means to understand processes yielding methane and allows for sources of methane to be mapped and classified through these processes; i.e. biogenic or thermogenic, oil vs. gas vs. coal gas-related. Here we present data obtained using a portable cavity ring-down spectrometry analyzer weighing less than 25 lbs and consuming less than 35W that simultaneously measures methane and ethane in real-time with a raw 1-σ precision of plane gas propagation.

Improving methane production from anaerobic digestion of Pennisetum Hybrid by alkaline pretreatment.

Science.gov (United States)

Kang, Xihui; Sun, Yongming; Li, Lianhua; Kong, Xiaoying; Yuan, Zhenhong

2018-05-01

Alkaline pretreatment with NaOH was used to improve methane yield from Pennisetum Hybrid. The pretreatments were carried out with different NaOH solutions (2-8% w/w) at three temperatures (35, 55 and 121 °C) for different periods of time (24, 24 and 1 h). All treated and untreated Pennisetum Hybrid were digested under mesophilic conditions (37 °C) to biogas, significant effects of the pretreatments on the yield of methane were observed. Results showed the modified Gompertz equation was reliable (determination coefficients (R 2 ) greater than 0.96) to describe the kinetic behavior of anaerobic digestion of Pennisetum Hybrid. The best result, obtained by the treatment at 35 °C 2% NaOH for 24 h, resulted in the methane yield of 301.7 mL/g VS, corresponding to 21.0% improvement in the methane yield. Compositional, SEM, XRD and FTIR analysis confirmed that lignin removal, structural modification and cellulose crystalline variation were responsible for the improvement. Copyright © 2018 Elsevier Ltd. All rights reserved.

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

Improving biogas quality and methane yield via co-digestion of agricultural and urban biomass wastes.

Science.gov (United States)

Poulsen, Tjalfe G; Adelard, Laetitia

2016-08-01

Impact of co-digestion versus mono-digestion on biogas and CH4 yield for a set of five biomass materials (vegetable food waste, cow dung, pig manure, grass clippings, and chicken manure) was investigated considering 95 different biomass mixes of the five materials under thermophilic conditions in bench-scale batch experiments over a period of 65days. Average biogas and CH4 yields were significantly higher during co-digestion than during mono-digestion of the same materials. This improvement was most significant for co-digestion experiments involving three biomass types, although it was independent of the specific biomasses being co-digested. Improvement in CH4 production was further more prominent early in the digestion process during co-digestion compared to mono-digestion. Co-digestion also appeared to increase the ultimate CH4/CO2 ratio of the gas produced compared to mono-digestion although this tendency was relatively weak and not statistically significant. Copyright © 2016 Elsevier Ltd. All rights reserved.

Direct Aromaization of Methane

Energy Technology Data Exchange (ETDEWEB)

George Marcelin

1997-01-15

The thermal decomposition of methane offers significant potential as a means of producing higher unsaturated and aromatic hydrocarbons when the extent of reaction is limited. Work in the literature previous to this project had shown that cooling the product and reacting gases as the reaction proceeds would significantly reduce or eliminate the formation of solid carbon or heavier (Clo+) materials. This project studied the effect and optimization of the quenching process as a means of increasing the amount of value added products during the pyrolysis of methane. A reactor was designed to rapidly quench the free-radical combustion reaction so as to maximize the yield of aromatics. The use of free-radical generators and catalysts were studied as a means of lowering the reaction temperature. A lower reaction temperature would have the benefits of more rapid quenching as well as a more feasible commercial process due to savings realized in energy and material of construction costs. It was the goal of the project to identify promising routes from methane to higher hydrocarbons based on the pyrolysis of methane.

Enhanced hydrolysis and methane yield by applying microaeration pretreatment to the anaerobic co-digestion of brown water and food waste

International Nuclear Information System (INIS)

Lim, Jun Wei; Wang, Jing-Yuan

2013-01-01

Highlights: ► Microaeration pretreatment was effective for brown water and food waste mixture. ► The added oxygen was consumed fully by facultative microorganisms. ► Enhanced solubilization, acidification and breakdown of SCFAs to acetate. ► Microaeration pretreatment improved methane yield by 10–21%. ► Nature of inoculum influenced the effects of microaeration. - Abstract: Microaeration has been used conventionally for the desulphurization of biogas, and recently it was shown to be an alternative pretreatment to enhance hydrolysis of the anaerobic digestion (AD) process. Previous studies on microaeration pretreatment were limited to the study of substrates with complex organic matter, while little has been reported on its effect on substrates with higher biodegradability such as brown water and food waste. Due to the lack of consistent microaeration intensities, previous studies were not comparable and thus inconclusive in proving the effectiveness of microaeration to the overall AD process. In this study, the role of microaeration pretreatment in the anaerobic co-digestion of brown water and food waste was evaluated in batch-tests. After a 4-day pretreatment with 37.5 mL-O 2 /L R -d added to the liquid phase of the reactor, the methane production of substrates were monitored in anaerobic conditions over the next 40 days. The added oxygen was consumed fully by facultative microorganisms and a reducing environment for organic matter degradation was maintained. Other than higher COD solubilization, microaeration pretreatment led to greater VFA accumulation and the conversion of other short chain fatty acids to acetate. This could be due to enhanced activities of hydrolytic and acidogenic bacteria and the degradation of slowly biodegradable compounds under microaerobic conditions. This study also found that the nature of inoculum influenced the effects of microaeration as a 21% and 10% increase in methane yield was observed when pretreatment was applied

Enhanced hydrolysis and methane yield by applying microaeration pretreatment to the anaerobic co-digestion of brown water and food waste

Energy Technology Data Exchange (ETDEWEB)

Lim, Jun Wei [Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 06-08 CleanTech One, 1 Cleantech Loop, Singapore 637141 (Singapore); School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore); Wang, Jing-Yuan, E-mail: jywang@ntu.edu.sg [Residues and Resource Reclamation Centre, Nanyang Environment and Water Research Institute, Nanyang Technological University, 06-08 CleanTech One, 1 Cleantech Loop, Singapore 637141 (Singapore); School of Civil and Environmental Engineering, Nanyang Technological University, 50 Nanyang Avenue, Singapore 639798 (Singapore)

2013-04-15

Highlights: ► Microaeration pretreatment was effective for brown water and food waste mixture. ► The added oxygen was consumed fully by facultative microorganisms. ► Enhanced solubilization, acidification and breakdown of SCFAs to acetate. ► Microaeration pretreatment improved methane yield by 10–21%. ► Nature of inoculum influenced the effects of microaeration. - Abstract: Microaeration has been used conventionally for the desulphurization of biogas, and recently it was shown to be an alternative pretreatment to enhance hydrolysis of the anaerobic digestion (AD) process. Previous studies on microaeration pretreatment were limited to the study of substrates with complex organic matter, while little has been reported on its effect on substrates with higher biodegradability such as brown water and food waste. Due to the lack of consistent microaeration intensities, previous studies were not comparable and thus inconclusive in proving the effectiveness of microaeration to the overall AD process. In this study, the role of microaeration pretreatment in the anaerobic co-digestion of brown water and food waste was evaluated in batch-tests. After a 4-day pretreatment with 37.5 mL-O{sub 2}/L{sub R}-d added to the liquid phase of the reactor, the methane production of substrates were monitored in anaerobic conditions over the next 40 days. The added oxygen was consumed fully by facultative microorganisms and a reducing environment for organic matter degradation was maintained. Other than higher COD solubilization, microaeration pretreatment led to greater VFA accumulation and the conversion of other short chain fatty acids to acetate. This could be due to enhanced activities of hydrolytic and acidogenic bacteria and the degradation of slowly biodegradable compounds under microaerobic conditions. This study also found that the nature of inoculum influenced the effects of microaeration as a 21% and 10% increase in methane yield was observed when pretreatment was

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.

Formation and retention of methane in coal

Energy Technology Data Exchange (ETDEWEB)

Hucka, V.J.; Bodily, D.M.; Huang, H.

1992-05-15

The formation and retention of methane in coalbeds was studied for ten Utah coal samples, one Colorado coal sample and eight coal samples from the Argonne Premium Coal Sample Bank.Methane gas content of the Utah and Colorado coals varied from zero to 9 cm{sup 3}/g. The Utah coals were all high volatile bituminous coals. The Colorado coal was a gassy medium volatile bituminous coal. The Argonne coals cover a range or rank from lignite to low volatile bituminous coal and were used to determine the effect of rank in laboratory studies. The methane content of six selected Utah coal seams and the Colorado coal seam was measured in situ using a special sample collection device and a bubble desorbometer. Coal samples were collected at each measurement site for laboratory analysis. The cleat and joint system was evaluated for the coal and surrounding rocks and geological conditions were noted. Permeability measurements were performed on selected samples and all samples were analyzed for proximate and ultimate analysis, petrographic analysis, {sup 13}C NMR dipolar-dephasing spectroscopy, and density analysis. The observed methane adsorption behavior was correlated with the chemical structure and physical properties of the coals.

Anaerobic co-digestion of the organic fraction of municipal solid waste with FOG waste from a sewage treatment plant: Recovering a wasted methane potential and enhancing the biogas yield

International Nuclear Information System (INIS)

Martin-Gonzalez, L.; Colturato, L.F.; Font, X.; Vicent, T.

2010-01-01

Anaerobic digestion is applied widely to treat the source collected organic fraction of municipal solid wastes (SC-OFMSW). Lipid-rich wastes are a valuable substrate for anaerobic digestion due to their high theoretical methane potential. Nevertheless, although fat, oil and grease waste from sewage treatment plants (STP-FOGW) are commonly disposed of in landfill, European legislation is aimed at encouraging more effective forms of treatment. Co-digestion of the above wastes may enhance valorisation of STP-FOGW and lead to a higher biogas yield throughout the anaerobic digestion process. In the present study, STP-FOGW was evaluated as a co-substrate in wet anaerobic digestion of SC-OFMSW under mesophilic conditions (37 o C). Batch experiments carried out at different co-digestion ratios showed an improvement in methane production related to STP-FOGW addition. A 1:7 (VS/VS) STP-FOGW:SC-OFMSW feed ratio was selected for use in performing further lab-scale studies in a 5 L continuous reactor. Biogas yield increased from 0.38 ± 0.02 L g VS feed -1 to 0.55 ± 0.05 L g VS feed -1 as a result of adding STP-FOGW to reactor feed. Both VS reduction values and biogas methane content were maintained and inhibition produced by long chain fatty acid (LCFA) accumulation was not observed. Recovery of a currently wasted methane potential from STP-FOGW was achieved in a co-digestion process with SC-OFMSW.

Abundant carbon substrates drive extremely high sulfate reduction rates and methane fluxes in Prairie Pothole Wetlands.

Science.gov (United States)

Dalcin Martins, Paula; Hoyt, David W; Bansal, Sheel; Mills, Christopher T; Tfaily, Malak; Tangen, Brian A; Finocchiaro, Raymond G; Johnston, Michael D; McAdams, Brandon C; Solensky, Matthew J; Smith, Garrett J; Chin, Yu-Ping; Wilkins, Michael J

2017-08-01

Inland waters are increasingly recognized as critical sites of methane emissions to the atmosphere, but the biogeochemical reactions driving such fluxes are less well understood. The Prairie Pothole Region (PPR) of North America is one of the largest wetland complexes in the world, containing millions of small, shallow wetlands. The sediment pore waters of PPR wetlands contain some of the highest concentrations of dissolved organic carbon (DOC) and sulfur species ever recorded in terrestrial aquatic environments. Using a suite of geochemical and microbiological analyses, we measured the impact of sedimentary carbon and sulfur transformations in these wetlands on methane fluxes to the atmosphere. This research represents the first study of coupled geochemistry and microbiology within the PPR and demonstrates how the conversion of abundant labile DOC pools into methane results in some of the highest fluxes of this greenhouse gas to the atmosphere ever reported. Abundant DOC and sulfate additionally supported some of the highest sulfate reduction rates ever measured in terrestrial aquatic environments, which we infer to account for a large fraction of carbon mineralization in this system. Methane accumulations in zones of active sulfate reduction may be due to either the transport of free methane gas from deeper locations or the co-occurrence of methanogenesis and sulfate reduction. If both respiratory processes are concurrent, any competitive inhibition of methanogenesis by sulfate-reducing bacteria may be lessened by the presence of large labile DOC pools that yield noncompetitive substrates such as methanol. Our results reveal some of the underlying mechanisms that make PPR wetlands biogeochemical hotspots, which ultimately leads to their critical, but poorly recognized role in regional greenhouse gas emissions. © 2017 John Wiley & Sons Ltd.

Abundant carbon substrates drive extremely high sulfate reduction rates and methane fluxes in Prairie Pothole Wetlands

Energy Technology Data Exchange (ETDEWEB)

Dalcin Martins, Paula [Microbiology Department, The Ohio State University, Columbus OH 43210 USA; Hoyt, David W. [Environmental Molecular Sciences Laboratory, Richland WA 99350 USA; Bansal, Sheel [United States Geological Survey - Northern Prairie Wildlife Research Center, Jamestown ND 58401 USA; Mills, Christopher T. [United States Geological Survey, Crustal Geophysics and Geochemistry Science Center, Building 20, Denver Federal Center Denver CO 80225 USA; Tfaily, Malak [Environmental Molecular Sciences Laboratory, Richland WA 99350 USA; Tangen, Brian A. [United States Geological Survey - Northern Prairie Wildlife Research Center, Jamestown ND 58401 USA; Finocchiaro, Raymond G. [United States Geological Survey - Northern Prairie Wildlife Research Center, Jamestown ND 58401 USA; Johnston, Michael D. [School of Earth Sciences, The Ohio State University, Columbus OH 43210 USA; McAdams, Brandon C. [School of Earth Sciences, The Ohio State University, Columbus OH 43210 USA; Solensky, Matthew J. [United States Geological Survey - Northern Prairie Wildlife Research Center, Jamestown ND 58401 USA; Smith, Garrett J. [Microbiology Department, The Ohio State University, Columbus OH 43210 USA; Chin, Yu-Ping [School of Earth Sciences, The Ohio State University, Columbus OH 43210 USA; Wilkins, Michael J. [Microbiology Department, The Ohio State University, Columbus OH 43210 USA; School of Earth Sciences, The Ohio State University, Columbus OH 43210 USA

2017-02-23

Inland waters are increasingly recognized as critical sites of methane emissions to the atmosphere, but the biogeochemical reactions driving such fluxes are less well understood. The Prairie Pothole Region (PPR) of North America is one of the largest wetland complexes in the world, containing millions of small, shallow wetlands. The sediment pore waters of PPR wetlands contain some of the highest concentrations of dissolved organic carbon (DOC) and sulfur species ever recorded in terrestrial aquatic environments. Using a suite of geochemical and microbiological analyses we measured the impact of sedimentary carbon and sulfur transformations in these wetlands on methane fluxes to the atmosphere. This research represents the first study of coupled geochemistry and microbiology within the PPR, and demonstrates how the conversion of abundant labile DOC pools into methane results in some of the highest fluxes of this greenhouse gas to the atmosphere ever reported. Abundant DOC and sulfate additionally supported some of the highest sulfate reduction rates ever measured in terrestrial aquatic environments, which we infer to account for a large fraction of carbon mineralization in this system. Methane accumulations in zones of active sulfate reduction may be due to either the transport of free methane gas from deeper locations, or the co-occurrence of methanogenesis and sulfate reduction. If both respiratory processes are concurrent, any competitive inhibition of methanogenesis by sulfate-reducing bacteria may be lessened by the presence of large labile DOC pools that yield non-competitive substrates such as methanol. Our results reveal some of the underlying mechanisms that make PPR wetlands biogeochemical hotspots, which ultimately leads to their critical, but poorly recognized role in regional greenhouse gas emissions.

A simple headspace equilibration method for measuring dissolved methane

Science.gov (United States)

Magen, C; Lapham, L.L.; Pohlman, John W.; Marshall, Kristin N.; Bosman, S.; Casso, Michael; Chanton, J.P.

2014-01-01

Dissolved methane concentrations in the ocean are close to equilibrium with the atmosphere. Because methane is only sparingly soluble in seawater, measuring it without contamination is challenging for samples collected and processed in the presence of air. Several methods for analyzing dissolved methane are described in the literature, yet none has conducted a thorough assessment of the method yield, contamination issues during collection, transport and storage, and the effect of temperature changes and preservative. Previous extraction methods transfer methane from water to gas by either a "sparge and trap" or a "headspace equilibration" technique. The gas is then analyzed for methane by gas chromatography. Here, we revisit the headspace equilibration technique and describe a simple, inexpensive, and reliable method to measure methane in fresh and seawater, regardless of concentration. Within the range of concentrations typically found in surface seawaters (2-1000 nmol L-1), the yield of the method nears 100% of what is expected from solubility calculation following the addition of known amount of methane. In addition to being sensitive (detection limit of 0.1 ppmv, or 0.74 nmol L-1), this method requires less than 10 min per sample, and does not use highly toxic chemicals. It can be conducted with minimum materials and does not require the use of a gas chromatograph at the collection site. It can therefore be used in various remote working environments and conditions.

Biogas crops grown in energy crop rotations: Linking chemical composition and methane production characteristics.

Science.gov (United States)

Herrmann, Christiane; Idler, Christine; Heiermann, Monika

2016-04-01

Methane production characteristics and chemical composition of 405 silages from 43 different crop species were examined using uniform laboratory methods, with the aim to characterise a wide range of crop feedstocks from energy crop rotations and to identify main parameters that influence biomass quality for biogas production. Methane formation was analysed from chopped and over 90 days ensiled crop biomass in batch anaerobic digestion tests without further pre-treatment. Lignin content of crop biomass was found to be the most significant explanatory variable for specific methane yields while the methane content and methane production rates were mainly affected by the content of nitrogen-free extracts and neutral detergent fibre, respectively. The accumulation of butyric acid and alcohols during the ensiling process had significant impact on specific methane yields and methane contents of crop silages. It is proposed that products of silage fermentation should be considered when evaluating crop silages for biogas production. Copyright © 2016 The Authors. Published by Elsevier Ltd.. All rights reserved.

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

Science.gov (United States)

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

2017-12-20

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

A model based on feature objects aided strategy to evaluate the methane generation from food waste by anaerobic digestion.

Science.gov (United States)

Yu, Meijuan; Zhao, Mingxing; Huang, Zhenxing; Xi, Kezhong; Shi, Wansheng; Ruan, Wenquan

2018-02-01

A model based on feature objects (FOs) aided strategy was used to evaluate the methane generation from food waste by anaerobic digestion. The kinetics of feature objects was tested by the modified Gompertz model and the first-order kinetic model, and the first-order kinetic hydrolysis constants were used to estimate the reaction rate of homemade and actual food waste. The results showed that the methane yields of four feature objects were significantly different. The anaerobic digestion of homemade food waste and actual food waste had various methane yields and kinetic constants due to the different contents of FOs in food waste. Combining the kinetic equations with the multiple linear regression equation could well express the methane yield of food waste, as the R 2 of food waste was more than 0.9. The predictive methane yields of the two actual food waste were 528.22 mL g -1  TS and 545.29 mL g -1  TS with the model, while the experimental values were 527.47 mL g -1  TS and 522.1 mL g -1  TS, respectively. The relative error between the experimental cumulative methane yields and the predicted cumulative methane yields were both less than 5%. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chemical pretreatment of lignocellulosic agroindustrial waste for methane production.

Science.gov (United States)

Pellera, Frantseska-Maria; Gidarakos, Evangelos

2018-01-01

This study investigates the effect of different chemical pretreatments on the solubilization and the degradability of different solid agroindustrial waste, namely winery waste, cotton gin waste, olive pomace and juice industry waste. Eight different reagents were investigated, i.e. sodium hydroxide (NaOH), sodium bicarbonate (NaHCO 3 ), sodium chloride (NaCl), citric acid (H 3 Cit), acetic acid (AcOH), hydrogen peroxide (H 2 O 2 ), acetone (Me 2 CO) and ethanol (EtOH), under three condition sets resulting in treatments of varying intensity, depending on process duration, reagent dosage and temperature. Results indicated that chemical pretreatment under more severe conditions is more effective on the solubilization of lignocellulosic substrates, such as those of the present study and among the investigated reagents, H 3 Cit, H 2 O 2 and EtOH appeared to be the most effective to this regard. At the same time, although chemical pretreatment in general did not improve the methane potential of the substrates, moderate to high severity conditions were found to generally be the most satisfactory in terms of methane production from pretreated materials. In fact, moderate severity treatments using EtOH for winery waste, H 3 Cit for olive pomace and H 2 O 2 for juice industry waste and a high severity treatment with EtOH for cotton gin waste, resulted in maximum specific methane yield values. Ultimately, the impact of pretreatment parameters on the different substrates seems to be dependent on their characteristics, in combination with the specific mode of action of each reagent. The overall energy balance of such a system could probably be improved by using lower operating powers and higher solid to liquid ratios. Copyright © 2017 Elsevier Ltd. All rights reserved.

Essentials for profitable coalbed methane production in the UK

Energy Technology Data Exchange (ETDEWEB)

Creel, J.C.; Rollins, J.B. [Cawley, Gillespie & Associates, Inc. (United Kingdom)

1995-12-31

The UK coalbed methane industry is now poised for a continuation of its growth. For this potential growth to be realized, coalbed methane production must be profitable for producers. Commercial viability of coalbed methane production in the UK depends on th fulfilment of essential technical, regulatory, and economic conditions. Technically, coalbed methane reservoirs must have an adequate thickness of permeable gas saturated coal. The regulatory environment must offer favorable treatment regarding taxation, royalties, and policies on well spacing, wellsite locations, and market accessibility. Economically, gas prices and initial capital costs must be sufficiently favorable to yield an acceptable rate of return. If these essential conditions can be fulfilled, UK coalbed methane production can be expected to be a commercially viable industry. 6 refs., 6 figs., 2 tabs.

Flux and energy dependence of methane production from graphite due to H+ impact

International Nuclear Information System (INIS)

Davis, J.W.; Haasz, A.A.; Stangeby, P.C.

1986-06-01

Carbon is in widespread use for limiter surfaces, as well as first wall coatings in current tokamaks. Chemical erosion via methane formation, due to energetic H + impact, is expected to contribute to the total erosion rate of carbon from these surfaces. Experimental results are presented for the methane yield from pyrolytic graphite due to H + exposure, using a mass analyzed ion beam. H + energies of 0.1-3 keV and flux densities of ∼ 5x10 13 to l0 16 H + /cm 2 s were used. The measured methane yield (CH 4 /H + ) initially increases with flux density, then reaches a maximum, which is followed by a gradual decrease. The magnitude of the maximum yield and the flux density at which it occurs depends on the graphite temperature. The yields obtained at temperatures corresponding to yield maxima at specific flux densities also show an initial increase, followed by a shallow maximum and a gradual decrease as a function of flux density; the maximum occurs at ∼10 15 H + /cm 2 s. Also presented are results on the methane production dependence on ion energy over the range 0.1 to 3 keV, and graphite temperature dependence measurements

The effect of aqueous ammonia soaking pretreatment on methane generation uing different lignocellulosic feedstocks

DEFF Research Database (Denmark)

Antonopoulou, Georgia; Jonuzaj, Suela; Gavala, Hariklia N.

2014-01-01

Lignocellulosic biomass including agricultural and forestry residues, perennial crops, softwoods and hardwoods, can be used as feedstock for methane production. Although being abundant and almost zero cost feedstocks, the main obstacles of their use are the low efficiencies and yields attained, d...... methane potential of switchgrass. Transactions of the ASABE. 53, 1921-1927 (2010) [3] Jurado, E., Gavala., H.N., Skiadas, I.V., :Enhancement of methane yield from wheat straw, miscanthus and willow using aqueous ammonia soaking. Environmental Tecnology. 34(13-14), 2069-2075 (2013)...

High-resolution passive sampling of dissolved methane in the water column of lakes in Greenland

Science.gov (United States)

Goldman, A. E.; Cadieux, S. B.; White, J. R.; Pratt, L. M.

2013-12-01

Arctic lakes are important participants in the global carbon cycle, releasing methane in a warming climate and contributing to a positive feedback to climate change. In order to yield detailed methane budgets and understand the implications of warming on methane dynamics, high-resolution profiles revealing methane behavior within the water column need to be obtained. Single day sampling using disruptive techniques has the potential to result in biases. In order to obtain high-resolution, undisturbed profiles of methane concentration and isotopic composition, this study evaluates a passive sampling method over a multi-day equilibration period. Selected for this study were two small lakes (Gatos Research Methane Carbon Isotope Analyzer. PDB sampling and pump sampling resulted in statistically similar concentrations (R2=0.89), ranging from 0.85 to 135 uM from PDB and 0.74 to 143 uM from pump sampling. In anoxic waters of the lake, where concentrations were high enough to yield robust isotopic results on the LGR MCIA, δ13C were also similar between the two methods, yielding -73‰ from PDB and -74‰ from pump sampling. Further investigation will produce results for a second lake and methane carbon and hydrogen isotopic composition for both lakes. Preliminary results for this passive sampling method are promising. We envision the use of this technique in future studies of dissolved methane and expect that it will provide a more finely resolved vertical profile, allowing for a more complete understanding of lacustrine methane dynamics.

Factors controlling headspace pressure in a manual manometric BMP method can be used to produce a methane output comparable to AMPTS.

Science.gov (United States)

Himanshu, H; Voelklein, M A; Murphy, J D; Grant, J; O'Kiely, P

2017-08-01

The manual manometric biochemical methane potential (mBMP) test uses the increase in pressure to calculate the gas produced. This gas production may be affected by the headspace volume in the incubation bottle and by the overhead pressure measurement and release (OHPMR) frequency. The biogas and methane yields of cellulose, barley, silage and slurry were compared with three incubation bottle headspace volumes (50, 90 and 180ml; constant 70ml total medium) and four OHPMR frequencies (daily, each third day, weekly and solely at the end of experiment). The methane yields of barley, silage and slurry were compared with those from an automated volumetric method (AMPTS). Headspace volume and OHPMR frequency effects on biogas yield were mediated mainly through headspace pressure, with the latter having a negative effect on the biogas yield measured and relatively little effect on methane yield. Two mBMP treatments produced methane yields equivalent to AMPTS. Copyright © 2017 Elsevier Ltd. All rights reserved.

Mechanistic insights into heterogeneous methane activation

International Nuclear Information System (INIS)

Latimer, Allegra A.; Aljama, Hassan; Kakekhani, Arvin; Yoo, Jong Suk; Kulkarni, Ambarish

2017-01-01

While natural gas is an abundant chemical fuel, its low volumetric energy density has prompted a search for catalysts able to transform methane into more useful chemicals. This search has often been aided through the use of transition state (TS) scaling relationships, which estimate methane activation TS energies as a linear function of a more easily calculated descriptor, such as final state energy, thus avoiding tedious TS energy calculations. It has been shown that methane can be activated via a radical or surface-stabilized pathway, both of which possess a unique TS scaling relationship. Herein, we present a simple model to aid in the prediction of methane activation barriers on heterogeneous catalysts. Analogous to the universal radical TS scaling relationship introduced in a previous publication, we show that a universal TS scaling relationship that transcends catalysts classes also seems to exist for surface-stabilized methane activation if the relevant final state energy is used. We demonstrate that this scaling relationship holds for several reducible and irreducible oxides, promoted metals, and sulfides. By combining the universal scaling relationships for both radical and surface-stabilized methane activation pathways, we show that catalyst reactivity must be considered in addition to catalyst geometry to obtain an accurate estimation for the TS energy. Here, this model can yield fast and accurate predictions of methane activation barriers on a wide range of catalysts, thus accelerating the discovery of more active catalysts for methane conversion.

Carbon monoxide and methane adsorption of crude oil refinery using activated carbon from palm shells as biosorbent

Science.gov (United States)

Yuliusman; Afdhol, M. K.; Sanal, Alristo

2018-03-01

Carbon monoxide and methane gas are widely present in oil refineries. Off-potential gas is used as raw material for the petrochemical industry. In order for this off-gas to be utilized, carbon monoxide and methane must be removed from off-gas. This study aims to adsorb carbon monoxide and methane using activated carbon of palm shells and commercial activated carbon simultaneously. This research was conducted in 2 stages: 1) Preparation and characterization of activated carbon, 2) Carbon monoxide and methane adsorption test. The activation experiments using carbon dioxide at a flow rate of 150 ml/min yielded a surface area of 978.29 m2/g, Nitrogen at flow rate 150 ml/min yielded surface area 1241.48 m2/g, and carbon dioxide and nitrogen at a flow rate 200 ml/min yielded a surface area 300.37 m2/g. Adsorption of carbon monoxide and methane on activated carbon of palm shell systems yielded results in the amount of 0.5485 mg/g and 0.0649 mg/g and using commercial activated carbon yielded results in the amount of 0.5480 mg/g and 0.0650 mg/g

Ultimate strength analysis of ring-stiffened cylinders subjected to hydrostatic pressure

International Nuclear Information System (INIS)

Park, Chi Mo

1990-01-01

In this study, ultimate strength analysis of ring-stiffened cylinders have been performed, considering the elasto-plastic large deflection. In the elasto-plastic analysis, von Mises yield criteria, the plastic flow theory and the layered approach have been adopted. In order to take into account the follower force effect of the hydrostatic pressure, the incremental load components have been updated at every loading step. As collapse modes, axisymmetric yielding, interframe shell buckling and general buckling are considered, while local buckling of ring-stiffener is not considered. Initial shape imperfection is assumed to be the elastic buckling mode to obtain the lower bound of the ultimate strength. Results of numerical analysis are compared with the experimental results to show the validity of the present approach. It has been drawn that the present numerical results are closely correlated with the experimental results. On the other hand, the effects of initial shape imperfection and condition on the ultimate strength have been investigated. (Author)

Bioelectrochemical enhancement of methane production from highly concentrated food waste in a combined anaerobic digester and microbial electrolysis cell.

Science.gov (United States)

Park, Jungyu; Lee, Beom; Tian, Donjie; Jun, Hangbae

2018-01-01

A microbial electrolysis cell (MEC) is a promising technology for enhancing biogas production from an anaerobic digestion (AD) reactor. In this study, the effects of the MEC on the rate of methane production from food waste were examined by comparing an AD reactor with an AD reactor combined with a MEC (AD+MEC). The use of the MEC accelerated methane production and stabilization via rapid organic oxidation and rapid methanogenesis. Over the total experimental period, the methane production rate and stabilization time of the AD+MEC reactor were approximately 1.7 and 4.0 times faster than those of the AD reactor. Interestingly however, at the final steady state, the methane yields of both the reactors were similar to the theoretical maximum methane yield. Based on these results, the MEC did not increase the methane yield over the theoretical value, but accelerated methane production and stabilization by bioelectrochemical reactions. Copyright © 2017 Elsevier Ltd. All rights reserved.

Production of Excess CO2 relative to methane in peatlands: a new H2 sink

Science.gov (United States)

Wilson, R.; Woodcroft, B. J.; Varner, R. K.; Tyson, G. W.; Tfaily, M. M.; Sebestyen, S.; Saleska, S. R.; Rogers, K.; Rich, V. I.; McFarlane, K. J.; Kostka, J. E.; Kolka, R. K.; Keller, J.; Iversen, C. M.; Hodgkins, S. B.; Hanson, P. J.; Guilderson, T. P.; Griffiths, N.; de La Cruz, F.; Crill, P. M.; Chanton, J.; Bridgham, S. D.; Barlaz, M.

2015-12-01

Methane is generated as the end product of anaerobic organic matter degradation following a series of reaction pathways including fermentation and syntrophy. Along with acetate and CO2, syntrophic reactions generate H2 and are only thermodynamically feasible when coupled to an exothermic reaction that consumes H2. The usual model of organic matter degradation in peatlands has assumed that methanogenesis is that exothermic H2-consuming reaction. If correct, this paradigm should ultimately result in equimolar production of CO2 and methane from the degradation of the model organic compound cellulose: i.e. C6H12O6 à 3CO2 + 3CH4. However, dissolved gas measurement and modeling results from field and incubation experiments spanning peatlands across the northern hemisphere have failed to demonstrate equimolar production of CO2 and methane. Instead, in a flagrant violation of thermodynamics, these studies show a large bias favoring CO2 production over methane generation. In this talk, we will use an array of complementary analytical techniques including FT-IR, cellulose and lignin measurements, 13C-NMR, fluorescence spectroscopy, and ultra-high resolution mass spectrometry to describe organic matter degradation within a peat column and identify the important degradation mechanisms. Hydrogenation was the most common transformation observed in the ultra-high resolution mass spectrometry data. From these results we propose a new mechanism for consuming H2 generated during CO2 production, without concomitant methane formation, consistent with observed high CO2/CH4 ratios. While homoacetogenesis is a known sink for H2 in these systems, this process also consumes CO2 and therefore does not explain the excess CO2 measured in field and incubation samples. Not only does the newly proposed mechanism consume H2 without generating methane, but it also yields enough energy to balance the coupled syntrophic reactions, thereby restoring thermodynamic order. Schematic of organic matter

Bio-methane via fast pyrolysis of biomass

International Nuclear Information System (INIS)

Görling, Martin; Larsson, Mårten; Alvfors, Per

2013-01-01

Highlights: ► Pyrolysis gases can efficiently be upgraded to bio-methane. ► The integration can increase energy efficiency and provide a renewable vehicle fuel. ► The biomass to bio-methane conversion efficiency is 83% (HHV). ► The efficiency is higher compared to bio-methane produced via gasification. ► Competitive alternative to other alternatives of bio-oil upgrading. - Abstract: Bio-methane, a renewable vehicle fuel, is today produced by anaerobic digestion and a 2nd generation production route via gasification is under development. This paper proposes a poly-generation plant that produces bio-methane, bio-char and heat via fast pyrolysis of biomass. The energy and material flows for the fuel synthesis are calculated by process simulation in Aspen Plus®. The production of bio-methane and bio-char amounts to 15.5 MW and 3.7 MW, when the total inputs are 23 MW raw biomass and 1.39 MW electricity respectively (HHV basis). The results indicate an overall efficiency of 84% including high-temperature heat and the biomass to bio-methane yield amounts to 83% after allocation of the biomass input to the final products (HHV basis). The overall energy efficiency is higher for the suggested plant than for the gasification production route and is therefore a competitive route for bio-methane production

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.

OXIDATIVE COUPLING OF METHANE USING INORGANIC MEMBRANE REACTORS

Energy Technology Data Exchange (ETDEWEB)

Dr. Y.H. Ma; Dr. W.R. Moser; Dr. A.G. Dixon; Dr. A.M. Ramachandra; Dr. Y. Lu; C. Binkerd

1998-04-01

The objective of this research is to study the oxidative coupling of methane in catalytic inorganic membrane reactors. A specific target is to achieve conversion of methane to C{sub 2} hydrocarbons at very high selectivity and higher yields than in conventional non-porous, co-feed, fixed bed reactors by controlling the oxygen supply through the membrane. A membrane reactor has the advantage of precisely controlling the rate of delivery of oxygen to the catalyst. This facility permits balancing the rate of oxidation and reduction of the catalyst. In addition, membrane reactors minimize the concentration of gas phase oxygen thus reducing non selective gas phase reactions, which are believed to be a main route for the formation of CO{sub x} products. Such gas phase reactions are a cause of decreased selectivity in the oxidative coupling of methane in conventional flow reactors. Membrane reactors could also produce higher product yields by providing better distribution of the reactant gases over the catalyst than the conventional plug flow reactors. Membrane reactor technology also offers the potential for modifying the membranes both to improve catalytic properties as well as to regulate the rate of the permeation/diffusion of reactants through the membrane to minimize by-product generation. Other benefits also exist with membrane reactors, such as the mitigation of thermal hot-spots for highly exothermic reactions such as the oxidative coupling of methane. The application of catalytically active inorganic membranes has potential for drastically increasing the yield of reactions which are currently limited by either thermodynamic equilibria, product inhibition, or kinetic selectivity.

Methane Production and Kinetic Modeling for Co-digestion of Manure with Lignocellulosic Residues

DEFF Research Database (Denmark)

Awais, Muhammad; Alvarado-Morales, Merlin; Tsapekos, Panagiotis

2016-01-01

L of CH4 g-1 of VS day-1, respectively. Moreover, the positive effects of coupled biological reactions in the reaction mixture of co-digestion were explained using the synergistic effect value (η). The η value was calculated using estimated and experimental methane yields. Furthermore, in MG co...... of different physicochemical characteristics with CM, the overall biodegradability compared to single-substrate digestion is improved and the methane yield is enhanced....

Study of Plant Growth Promoting Rhizobacteria (PGPR and Drought on Physiological Traits and Ultimate Yield of Cultivars of Oilseed Rape (Brassica spp. L.

Directory of Open Access Journals (Sweden)

pooya arvin

2018-02-01

Full Text Available Introduction Oilseed rape (Brassica spp L. is one of the valuable oilseed crops which has been attracting attention in recent years. Iran is located in a semi-arid region, and water shortage has caused problems, namely providing drinking water as much as water supply for crop production. Not only does Plant Growth Promoting Rhizobacteria (PGPR make plant growth stimulating hormones like Auxin and Gibberellin but also can ease stress conditions by producing ABA. Consequently, considering the current water shortage crisis in Iran, we took three main criteria into account: the roles of PGPRs in increasing resistance to abiotic stress, relief of drought effects, and the importance of cultivation of oilseed rape. The present research has been compiled to study drought and some Plant Growth Promoting Rhizobacteria (PGPR on Physiological Traits and Ultimate Yield of Cultivars of Oilseed Rape. Materials and Methods The current study was done on the basis of two simultaneous experiments (under stress and non-stress experiments during 2010- 2011 growing season at Agriculture and Natural Resources Research Station of Torogh, Mashhad is situated in East-North of Iran (36° N, 59° E, 1003 ASL . Two research sites (under stress and no-stress fields were selected beside each other. This region has a semi-arid climate (annual rainfall 286 mm. The experimental design was factorial based on randomized completely block design with three replications in each experiment. The first treatment was Plant Growth Promoting Rizobactria, including B0: no inoculation (control, B1: co-inoculation (Pseudomonas flourescens 169+P. putida 108, B2: inoculation with P. flourescens 169 and B3: inoculation with P. putida 108. Second treatment was cultivar, including Hayola401 and Hayola330 cultivars belong to Brassica napus, Parkland and Goldrush cultivars belong to B. rapa and BP18 and landrace cultivars belong to B.juncea .Greenness index, plant height, relative water content

Yield, utilization, storage and ultimate storage of depleted uranium

International Nuclear Information System (INIS)

Aumueller, L.; Hermann, J.

1977-11-01

More than 80% of the uranium leaving uranium enrichment plants is depleted to a residual content of about 0,25% U 235. Due to the present ineconomical further depletion to the technically possible residual content of 0,1% U 235, the so-called 'tails' are first of all stored. The quantity of stored depleted uranium in the FRG should be about 100.000 t by the year 2000. It represents a strategic reserve for future energy supply regardless of profitableness. The study analysis the conceivable possible uses for the tails quantity considered. These are, besides further depletion whose profitableness is considered, also the use as breeder material in breeder reactors and the use in the non-nuclear field. The main part of the study deals with the various storage possibilities of the depleted uranium in oxidic or fluoride form. A comparison of costs of alternative storage concepts showed a clear advantage for the storage of UF 6 in 48 inch containers already in use. The conceivable accidents in storing are analyzed and measures to reduce the consequences are discussed. Finally, the problems of ultimate storage for the remaining waste after further depletion or use are investigated and the costs arising here are also estimated. (RB) [de

An integrated system for hydrogen and methane production during landfill leachate treatment

Energy Technology Data Exchange (ETDEWEB)

Hafez, H.M.; Nakhla, G.; El Naggar, H. [Western Ontario Univ., London, ON (Canada). Dept. of Civil and Environmental Engineering

2009-07-01

This paper described a patent-pending integrated waste-to-energy system that includes a novel biohydrogen reactor with a gravity settler and a second stage conventional anaerobic digester for the production of methane gas. This chemical-free process was tested using a synthetic wastewater/leachate solution at 37 degrees C for 45 days. During the experimental period, the biohydrogenator steadily produced hydrogen (H{sub 2}) with no methane. The maximum hydrogen yield was 400 ml H{sub 2}/g glucose with an average of 345 ml H{sub 2}/g glucose, as compared to 141 and 118 ml H{sub 2}/g glucose for two consecutive runs done in parallel using a conventional continuously stirrer tank reactor. The maximum and average hydrogen production rates in the biohydrogen reactor with gravity settler were 22 and 19 L H{sub 2}/day, the maximum yield was 2.8 mol H{sub 2} /mol glucose higher than 1.6-2.3 mol H{sub 2}/mol glucose reported for continuous-flow reactors. The methane yield for the second stage approached a maximum value of 426 ml methane/g chemical oxygen demand (COD) removed.

Chlorella vulgaris vs cyanobacterial biomasses: Comparison in terms of biomass productivity and biogas yield

International Nuclear Information System (INIS)

Mendez, Lara; Mahdy, Ahmed; Ballesteros, Mercedes; González-Fernández, Cristina

2015-01-01

Highlights: • Cyanobacteria and C. vulgaris were compared in terms of growth and methane production. • Biomasses were subjected to anaerobic digestion without applying any disruption method. • Cyanobacteria showed an increased methane yield in comparison with C. vulgaris. - Abstract: The aim of the present study was to compare cyanobacteria strains (Aphanizomenon ovalisporum, Anabaena planctonica, Borzia trilocularis and Synechocystis sp.) and microalgae (Chlorella vulgaris) in terms of growth rate, biochemical profile and methane production. Cyanobacteria growth rate ranged 0.5–0.6 day −1 for A. planctonica, A. ovalisporum and Synecochystis sp. and 0.4 day −1 for B. tricularis. Opposite, C. vulgaris maximum growth rate was double (1.2 day −1 ) than that of cyanobacteria. Regarding the methane yield, microalgae C. vulgaris averaged 120 mL CH 4 g COD in −1 due to the presence of a strong cell wall. On the other hand, anaerobic digestion of cyanobacteria supported higher methane yields. B. trilocularis and A. planctonica presented 1.42-fold higher methane yield than microalgae while this value was raised to approximately 1.85-fold for A. ovalisporum and Synechochystis sp. In the biogas production context, this study showed that the low growth rates of cyanobacteria can be overcome by their increased anaerobic digestibility when compared to their microalgae counterpartners, such is the case of C. vulgaris

Plasma Thermal Conversion of Methane to Acetylene

International Nuclear Information System (INIS)

Fincke, James Russell; Anderson, Raymond Paul; Hyde, Timothy Allen; Detering, Brent Alan; Wright, Randy Ben; Bewley, Randy Lee; Haggard, Delon C; Swank, William David

2002-01-01

This paper describes a re-examination of a known process for the direct plasma thermal conversion of methane to acetylene. Conversion efficiencies (% methane converted) approached 100% and acetylene yields in the 90-95% range with 2-4% solid carbon production were demonstrated. Specificity for acetylene was higher than in prior work. Improvements in conversion efficiency, yield, and specificity were due primarily to improved injector design and reactant mixing, and minimization of temperature gradients and cold boundary layers. At the 60-kilowatt scale cooling by wall heat transfer appears to be sufficient to quench the product stream and prevent further reaction of acetylene resulting in the formation of heavier hydrocarbon products or solid carbon. Significantly increasing the quenching rate by aerodynamic expansion of the products through a converging-diverging nozzle led to a reduction in the yield of ethylene but had little effect on the yield of other hydrocarbon products. While greater product selectivity for acetylene has been demonstrated, the specific energy consumption per unit mass of acetylene produced was not improved upon. A kinetic model that includes the reaction mechanisms resulting in the formation of acetylene and heavier hydrocarbons, through benzene, is described

Oxidative coupling of methane using inorganic membrane reactor

Energy Technology Data Exchange (ETDEWEB)

Ma, Y.H.; Moser, W.R.; Dixon, A.G. [Worcester Polytechnic Institute, MA (United States)] [and others

1995-12-31

The goal of this research is to improve the oxidative coupling of methane in a catalytic inorganic membrane reactor. A specific target is to achieve conversion of methane to C{sub 2} hydrocarbons at very high selectivity and relatively higher yields than in fixed bed reactors by controlling the oxygen supply through the membrane. A membrane reactor has the advantage of precisely controlling the rate of delivery of oxygen to the catalyst. This facility permits balancing the rate of oxidation and reduction of the catalyst. In addition, membrane reactors minimize the concentration of gas phase oxygen thus reducing non selective gas phase reactions, which are believed to be a main route for formation of CO{sub x} products. Such gas phase reactions are a cause for decreased selectivity in oxidative coupling of methane in conventional flow reactors. Membrane reactors could also produce higher product yields by providing better distribution of the reactant gases over the catalyst than the conventional plug flow reactors. Modeling work which aimed at predicting the observed experimental trends in porous membrane reactors was also undertaken in this research program.

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.

Formation and retention of methane in coal. Final report

Energy Technology Data Exchange (ETDEWEB)

Hucka, V.J.; Bodily, D.M.; Huang, H.

1992-05-15

The formation and retention of methane in coalbeds was studied for ten Utah coal samples, one Colorado coal sample and eight coal samples from the Argonne Premium Coal Sample Bank.Methane gas content of the Utah and Colorado coals varied from zero to 9 cm{sup 3}/g. The Utah coals were all high volatile bituminous coals. The Colorado coal was a gassy medium volatile bituminous coal. The Argonne coals cover a range or rank from lignite to low volatile bituminous coal and were used to determine the effect of rank in laboratory studies. The methane content of six selected Utah coal seams and the Colorado coal seam was measured in situ using a special sample collection device and a bubble desorbometer. Coal samples were collected at each measurement site for laboratory analysis. The cleat and joint system was evaluated for the coal and surrounding rocks and geological conditions were noted. Permeability measurements were performed on selected samples and all samples were analyzed for proximate and ultimate analysis, petrographic analysis, {sup 13}C NMR dipolar-dephasing spectroscopy, and density analysis. The observed methane adsorption behavior was correlated with the chemical structure and physical properties of the coals.

Catalytic aromatization of methane.

Science.gov (United States)

Spivey, James J; Hutchings, Graham

2014-02-07

Recent developments in natural gas production technology have led to lower prices for methane and renewed interest in converting methane to higher value products. Processes such as those based on syngas from methane reforming are being investigated. Another option is methane aromatization, which produces benzene and hydrogen: 6CH4(g) → C6H6(g) + 9H2(g) ΔG°(r) = +433 kJ mol(-1) ΔH°(r) = +531 kJ mol(-1). Thermodynamic calculations for this reaction show that benzene formation is insignificant below ∼600 °C, and that the formation of solid carbon [C(s)] is thermodynamically favored at temperatures above ∼300 °C. Benzene formation is insignificant at all temperatures up to 1000 °C when C(s) is included in the calculation of equilibrium composition. Interestingly, the thermodynamic limitation on benzene formation can be minimized by the addition of alkanes/alkenes to the methane feed. By far the most widely studied catalysts for this reaction are Mo/HZSM-5 and Mo/MCM-22. Benzene selectivities are generally between 60 and 80% at methane conversions of ∼10%, corresponding to net benzene yields of less than 10%. Major byproducts include lower molecular weight hydrocarbons and higher molecular weight substituted aromatics. However, carbon formation is inevitable, but the experimental findings show this can be kinetically limited by the use of H2 or oxidants in the feed, including CO2 or steam. A number of reactor configurations involving regeneration of the carbon-containing catalyst have been developed with the goal of minimizing the cost of regeneration of the catalyst once deactivated by carbon deposition. In this tutorial review we discuss the thermodynamics of this process, the catalysts used and the potential reactor configurations that can be applied.

Biomass and biomass and biogas yielding potential of sorghum as affected by planting density, sowing time and cultivar

International Nuclear Information System (INIS)

Mahmood, A.; Hussain, A.; Shahzad, A. N.; Honermeier, B.

2015-01-01

Biogas from biomass is a promising renewable energy source whose importance is increasing in European as well as in other countries. A field experiment at one location (Experimental Station Giessen, Justus Liebig University of Giessen, Germany) over two years was designed to study the effect of altering sowing time (ST), planting density and cultivar on the biomass yield and chemical composition of biomass sorghum, and its potential for methane production. Of the two cultivars tested, cv. Goliath (intraspecific hybrid) was more productive with respect to biomass yield than cv. Bovital (S. bicolor x S. sudanense hybrid). ST also influenced biomass yield and most of the quality parameters measured. Delayed sowing was in general advantageous. The choice of cultivar had a marked effect on biogas and methane yield. The highest biogas and methane yields were produced by late sown cv. Bovital. Sub-optimal planting densities limited biomass accumulation of the crop, however neither the chemical composition nor the methane yield was affected by planting density. (author)

Methane from benzene in argon dielectric barrier discharge

International Nuclear Information System (INIS)

Das, Tomi Nath; Dey, G.R.

2013-01-01

Highlights: ► Efficient on-line conversion of benzene to methane at room temperature. ► Absence of other H-atom donor suggests new type of chemistry. ► For parent loss > 90%, methane yield was ∼40% of limit due to H-atom availability. ► Surface moisture contributed ·OH radical for trace phenolic products’ formation. ► This method may emerge as an exploitable tactic for pollutants’ usable alterations. -- Abstract: A first-time account of direct, on-line, instantaneous and efficient chemical conversion of gas phase benzene to methane in argon Dielectric Barrier Discharge (DBD) is presented. In the absence of another overt hydrogen-donating source, potency of analogous parents toward methane generation is found to follow the order: benzene > toluene > p-xylene. Simultaneous production of trace amounts of phenolic surface deposits suggest (a) prompt decomposition of the parent molecules, including a large fraction yielding atomic transients (H-atom), (b) continuous and appropriate recombination of such parts, and (c) trace moisture in parent contributing ·OH radicals and additional H-atoms, which suitably react with the unreacted fraction of the parent, and also other intermediates. Results highlight Ar DBD to be a simple and exploitable technology for transforming undesirable hazardous aromatics to usable/useful low molecular weight open-chain products following the principles of green chemistry and engineering

Concentration and isotope composition of atmospheric methane in Walbrzych Coal District

International Nuclear Information System (INIS)

Korus, A.; Necki, J.; Kotarba, M.

2002-01-01

The closure of hard coal mines in the Walbrzych Coal District led to the reconstruction of carboniferous groundwater horizon and migration of carbon dioxide and methane upward to the surface. Migration of methane is facilitated by systems of fractures, faults and by dense network of shafts, which still remain in connection with the surface. Measurement of the isotopic composition (δ 13 CH 4 ) of methane together with its concentration in atmosphere, yield useful information on the contribution of anthropogenic sources to regional budget of methane. A two component-mixing model was applied to distinguish anthropogenic source. The result of the study, current parameters of anthropogenic source are presented. (author)

Hydrogen and methane production from household solid waste in the two-stage fermentation process

DEFF Research Database (Denmark)

Lui, D.; Liu, D.; Zeng, Raymond Jianxiong

2006-01-01

A two-stage process combined hydrogen and methane production from household solid waste was demonstrated working successfully. The yield of 43 mL H-2/g volatile solid (VS) added was generated in the first hydrogen production stage and the methane production in the second stage was 500 mL CH4/g VS...... added. This figure was 21% higher than the methane yield from the one-stage process, which was run as control. Sparging of the hydrogen reactor with methane gas resulted in doubling of the hydrogen production. PH was observed as a key factor affecting fermentation pathway in hydrogen production stage....... Furthermore, this study also provided direct evidence in the dynamic fermentation process that, hydrogen production increase was reflected by acetate to butyrate ratio increase in liquid phase. (c) 2006 Elsevier Ltd. All rights reserved....

A Green Process for High-Concentration Ethylene and Hydrogen Production from Methane in a Plasma-Followed-by-Catalyst Reactor

International Nuclear Information System (INIS)

Wang Kangjun; Li Xiaosong; Zhu Aimin

2011-01-01

A green process for the oxygen-free conversion of methane to high-concentration ethylene and hydrogen in a plasma-followed-by-catalyst (PFC) reactor is presented. Without any catalysts and with pure methane used as the feed gas, a stable kilohertz spark discharge leads to an acetylene yield of 64.1%, ethylene yield of 2.5% and hydrogen yield of 59.0% with 80.0% of methane conversion at a methane flow rate of 50 cm 3 /min and a specific input energy of 38.4 kJ/L. In the effluent gas from a stable kilohertz spark discharge reactor, the concentrations of acetylene, ethylene and hydrogen were 18.1%, 0.7% and 66.9%, respectively. When catalysts Pd-Ag/SiO 2 were employed in the second stage with discharge conditions same as in the case of plasma alone, the PFC reactor provides an ethylene yield of 52.1% and hydrogen yield of 43.4%. The concentrations of ethylene and hydrogen in the effluent gas from the PFC reactor were found to be as high as 17.1% and 62.6%, respectively. Moreover, no acetylene was detected in the effluent gas. This means that a high concentration of ethylene and oxygen-free hydrogen can be co-produced directly from methane in the PFC reactor.

Conversion of Methane to C2 Hydrocarbons and Hydrogen Using a Gliding Arc Reactor

International Nuclear Information System (INIS)

Hu Shuanghui; Wang Baowei; Lv Yijun; Yan Wenjuan

2013-01-01

Methane conversion has been studied using gliding arc plasma in the presence of argon. The process was conducted at atmospheric pressure and ambient temperature. The focus of this research was to develop a process of converting methane to C 2 hydrocarbons and hydrogen. The main parameters, including the CH 4 /Ar mole ratio, the CH 4 flow rate, the input voltage, and the minimum electrode gap, were varied to investigate their effects on methane conversion rate, product distribution, energy consumption, carbon deposit, and reaction stability. The specific energy requirement (SER) was used to express the energy utilization efficiency of the process and provided a practical guidance for optimizing reaction conditions for improving energy efficiency. It was found that the carbon deposition was not conducive to methane conversion, and the gliding arc plasma discharge reached a stable state twelve minutes later. Optimum conditions for methane conversion were suggested. The maximum methane conversion rate of 43.39% was obtained under the optimum conditions. Also, C 2 hydrocarbons selectivity, C 2 hydrocarbons yield, H 2 selectivity, H 2 yield and SER were 87.20%, 37.83%, 81.28%, 35.27%, and 2.09 MJ/mol, respectively.

Anaerobic digestion of macroalgae: methane potentials, pre-treatment, inhibition and co-digestion

DEFF Research Database (Denmark)

Bangsø Nielsen, Henrik; Heiske, Stefan

2011-01-01

In the present study we tested four macroalgae species – harvested in Denmark – for their suitability of bioconversion to methane. In batch experiments (53 WC) methane yields varied from 132 ml g volatile solids1 (VS) for Gracillaria vermiculophylla, 152 ml g VS1 for Ulva lactuca, 166 ml g VS1...

Ultimate analysis of PWR prestressed concrete containment subjected to internal pressure

International Nuclear Information System (INIS)

Hu, H.-T.; Lin, Y.-H.

2006-01-01

Numerical analyses are carried out by using the ABAQUS finite element program to predict the ultimate pressure capacity and the failure mode of the PWR prestressed concrete containment at Maanshan nuclear power plant. Material nonlinearity such as concrete cracking, tension stiffening, shear retention, concrete plasticity, yielding of prestressing tendon, yielding of steel reinforcing bar and degradation of material properties due to high temperature are all simulated with proper constitutive models. Geometric nonlinearity due to finite deformation has also been considered. The results of the analysis show that when the prestressed concrete containment fails, extensive cracks take place at the apex of the dome, the junction of the dome and cylinder, and the bottom of the cylinder connecting to the base slab. In addition, the ultimate pressure capacity of the containment is higher than the design pressure by 86%

Biohydrogen and methane production by co-digestion of cassava stillage and excess sludge under thermophilic condition.

Science.gov (United States)

Wang, Wen; Xie, Li; Chen, Jinrong; Luo, Gang; Zhou, Qi

2011-02-01

Thermophilic anaerobic hydrogen and methane production by co-digestion of cassava stillage (CS) and excess sludge (ES) was investigated in this study. The improved hydrogen and subsequent methane production were observed by co-digestion of CS with certain amount of ES in batch experiments. Compared with one phase anaerobic digestion, two phase anaerobic digestion offered an attractive alternative with more abundant biogas production and energy yield, e.g., the total energy yield in two phase obtained at VS(CS)/VS(ES) of 3:1 was 25% higher than the value of one phase. Results from continuous experiments further demonstrated that VS(CS)/VS(ES) of 3:1 was optimal for hydrogen production with the highest hydrogen yield of 74 mL/gtotal VS added, the balanced nutrient condition with C/N ratio of 1.5 g carbohydrate-COD/gprotein-COD or 11.9 g C/gN might be the main reason for such enhancement. VS(CS)/VS(ES) of 3:1 was also optimal for continuous methane production considering the higher methane yield of 350 mL/gtotal VS added and the lower propionate concentration in the effluent. Copyright © 2010 Elsevier Ltd. All rights reserved.

High-Titer Methane from Organosolv-Pretreated Spruce and Birch

Directory of Open Access Journals (Sweden)

Leonidas Matsakas

2017-02-01

Full Text Available The negative impact of fossil fuels and the increased demand for renewable energy sources has led to the use of novel raw material sources. Lignocellulosic biomass could serve as a possible raw material for anaerobic digestion and production of biogas. This work is aimed at using forest biomass, both softwood (spruce and hardwood (birch, as a raw material for anaerobic digestion. We examined the effect of different operational conditions for the organosolv pretreatment (ethanol content, duration of treatment, and addition of acid catalyst on the methane yield. In addition, we investigated the effect of addition of cellulolytic enzymes during the digestion. We found that inclusion of an acid catalyst during organosolv pretreatment improved the yields from spruce, but it did not affect the yields from birch. Shorter duration of treatment was advantageous with both materials. Methane yields from spruce were higher with lower ethanol content whereas higher ethanol content was more beneficial for birch. The highest yields obtained were 185 mL CH4/g VS from spruce and 259.9 mL CH4/g VS from birch. Addition of cellulolytic enzymes improved these yields to 266.6 mL CH4/g VS and 284.2 mL CH4/g VS, respectively.

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.

Decreasing methane yield with increasing food intake keeps daily methane emissions constant in two foregut fermenting marsupials, the western grey kangaroo and red kangaroo.

Science.gov (United States)

Vendl, Catharina; Clauss, Marcus; Stewart, Mathew; Leggett, Keith; Hummel, Jürgen; Kreuzer, Michael; Munn, Adam

2015-11-01

Fundamental differences in methane (CH4) production between macropods (kangaroos) and ruminants have been suggested and linked to differences in the composition of the forestomach microbiome. Using six western grey kangaroos (Macropus fuliginosus) and four red kangaroos (Macropus rufus), we measured daily absolute CH4 production in vivo as well as CH4 yield (CH4 per unit of intake of dry matter, gross energy or digestible fibre) by open-circuit respirometry. Two food intake levels were tested using a chopped lucerne hay (alfalfa) diet. Body mass-specific absolute CH4 production resembled values previously reported in wallabies and non-ruminant herbivores such as horses, and did not differ with food intake level, although there was no concomitant proportionate decrease in fibre digestibility with higher food intake. In contrast, CH4 yield decreased with increasing intake, and was intermediate between values reported for ruminants and non-ruminant herbivores. These results correspond to those in ruminants and other non-ruminant species where increased intake (and hence a shorter digesta retention in the gut) leads to a lower CH4 yield. We hypothesize that rather than harbouring a fundamentally different microbiome in their foregut, the microbiome of macropods is in a particular metabolic state more tuned towards growth (i.e. biomass production) rather than CH4 production. This is due to the short digesta retention time in macropods and the known distinct 'digesta washing' in the gut of macropods, where fluids move faster than particles and hence most likely wash out microbes from the forestomach. Although our data suggest that kangaroos only produce about 27% of the body mass-specific volume of CH4 of ruminants, it remains to be modelled with species-specific growth rates and production conditions whether or not significantly lower CH4 amounts are emitted per kg of meat in kangaroo than in beef or mutton production. © 2015. Published by The Company of Biologists Ltd.

Development, implementation and validation of a practice-orientated method for the determination of yields of biogas or methane, respectively; Entwicklung, Implementierung und Validierung eines praxisnahen Verfahrens zur Bestimmung von Biogas- bzw. Methanertraegen

Energy Technology Data Exchange (ETDEWEB)

Fritz, Thomas

2008-12-15

The increasing number of the world population results in a pronounced ascent of the world-wide energy consumption. This problem additionally is strengthened by the release of carbon dioxide. In the contribution under consideration, the author develops a method with which the yields of fermentation gas or methane, respectively, reliably as well as practice-orientated can be determined. Different influences on the determination of these yields are described. Thus, the investigations in this area are to be standardised further. The comparability under laboratories is to be increased. (orig.) [German] Die steigende Zahl der Weltbevoelkerung fuehrt zu einem Ausgepraegten Anstieg des weltweiten Energieverbrauchs. Diese Problematik wird durch die Freisetzung von Kohlendioxid zusaetzlich verstaerkt. Im vorliegenden Beitrag entwickelt der Autor eine Methode, mit der die Ertraege von Biogas beziehungsweise Methan zuverlaesslich und praxisnah bestimmt werden koennen. Es werden verschiedene Einfluesse auf die Bestimmung dieser Ertraege dargestellt. Damit sollen die Untersuchungen auf diesem Gebiet weiter standardisiert und die Vergleichbarkeit unter Laboren erhoeht werden.

Anaerobic digestion of macroalgae: methane potentials, pre-treatment, inhibition and co-digestion.

Science.gov (United States)

Nielsen, H B; Heiske, S

2011-01-01

In the present study we tested four macroalgae species--harvested in Denmark--for their suitability of bioconversion to methane. In batch experiments (53 degrees C) methane yields varied from 132 ml g volatile solids(-1) (VS) for Gracillaria vermiculophylla, 152 mi gVS(-1) for Ulva lactuca, 166 ml g VS(-1) for Chaetomorpha linum and 340 ml g VS(-1) for Saccharina latissima following 34 days of incubation. With an organic content of 21.1% (1.5-2.8 times higher than the other algae) S. latissima seems very suitable for anaerobic digestion. However, the methane yields of U. lactuca, G. vermiculophylla and C. linum could be increased with 68%, 11% and 17%, respectively, by pretreatment with maceration. U. lactuca is often observed during 'green tides' in Europe and has a high cultivation potential at Nordic conditions. Therefore, U. lactuca was selected for further investigation and co-digested with cattle manure in a lab-scale continuously stirred tank reactor. A 48% increase in methane production rate of the reactor was observed when the concentration of U. lactuca in the feedstock was 40% (VS basis). Increasing the concentration to 50% had no further effect on the methane production, which limits the application of this algae at Danish centralized biogas plant.

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.

Evaluation of anaerobic co-digestion of dairy manure with food wastes via bio-methane potential assay and CSTR reactor.

Science.gov (United States)

Ye, Yulin; Zamalloa, Carlos; Lin, Hongjian; Yan, Mi; Schmidt, David; Hu, Bo

2015-01-01

The introduction of food wastes into anaerobic digestion (AD) brings a promising scenario of increasing feedstock availability and overall energy production from AD. This study evaluated the biodegradability and methane potential from co-digestion of two typical food wastes, kitchen waste and chicken fat, with dairy manure. For single substrate, the bio-methane potential assays showed that kitchen waste had the highest methane yield of 352 L-CH4 kg(-1)-VS added, 92% more than dairy manure alone. Chicken fat at the same Volatile Solid (VS) level (2 g L(-1)) inhibited bio-methane production. Addition of kitchen waste and chicken fat to a VS percentage of up to 40% improved overall methane yield by 44% and 34%, respectively. Synergistic effect was observed when either combining two or three substrates as AD feedstock, possibly as a result of increased biodegradability of organic materials in chicken fat and kitchen waste compared with dairy manure. Addition of chicken fat improved methane yield more than kitchen waste. However, addition of chicken fat VS over 0.8 g L(-1) should be cautiously done because it may cause reactor failure due to decrease in pH. The maximum methane yield was 425 L-CH4 kg(-1)-VS, achieved at a VS ratio of 2:2:1 for kitchen waste, chicken fat, and dairy manure. Results from batch AD experiment demonstrated that supplementing dairy manure to chicken fat and/or kitchen waste improved alkalinity of substrate due to the inclusion of more titratable bases in dairy manure, and therefore stabilized the methanogenesis and substantially improved biogas yield. A mixture of substrates of kitchen waste, chicken fat, and dairy manure at a ratio of 1:1:3 was fed to a continuously stirred tank reactor operated at organic loading rates of 3.28, 6.55, and 2.18 g-COD L(-1)-day (hydraulic retention time of 20, 10, and 30 days, respectively) under mesophilic condition, and methane production rate reached 0.65, 0.95, and 0.34 L-CH4 L(-1)-reactor-day.

Ventilation air methane destruction - the new challenge to the underground coal mining industry

International Nuclear Information System (INIS)

Clarke, Michael; Seddon, Duncan

2012-01-01

With the advent of 'Carbon Taxes' the carbon footprint of coal has become an economic as well as an environmental issue and the emission of methane in mine out- bye air as ventilation air methane (VAM) is a pending liability. As well as being economic and environmental concerns, VAM and VAM management have safety, social licence and operational factors that must also be addressed. The need to mitigate (oxidise) methane to produce carbon dioxide and water vapour (VAM destruction) and thus lower the Greenhouse footprint is coming to be seen as a necessary mining activity. However, there are several key issues to be addressed with present technology using high temperature (1000°C) thermal oxidisers. Emerging technology may involve a catalytic approach. This technology aims to lower the oxidation temperature and produce a more efficient combustion process. Several systems (based on both precious metals and transition metals) have been shown to operate below 400°C. An ultimate solution would be oxidation at ambient temperature, which is clearly demonstrated by the enzyme methane mono-oxygenase (MMO) which oxidises methane to methanol. However, the rate of oxidation at ambient temperature is too low and the structure of the bio-reactors required would be very large. The challenge is to marry the natural oxidation with modern catalytic approaches and achieve high rates of methane oxidation, in compact equipment, well below the methane auto-ignition temperature.

Assessment of hydrothermal pretreatment of various lignocellulosic biomass with CO2 catalyst for enhanced methane and hydrogen production.

Science.gov (United States)

Eskicioglu, Cigdem; Monlau, Florian; Barakat, Abdellatif; Ferrer, Ivet; Kaparaju, Prasad; Trably, Eric; Carrère, Hélène

2017-09-01

Hydrothermal pretreatment of five lignocellulosic substrates (i.e. wheat straw, rice straw, biomass sorghum, corn stover and Douglas fir bark) were conducted in the presence of CO 2 as a catalyst. To maximize disintegration and conversion into bioenergy (methane and hydrogen), pretreatment temperatures and subsequent pressures varied with a range of 26-175 °C, and 25-102 bars, respectively. Among lignin, cellulose and hemicelluloses, hydrothermal pretreatment caused the highest reduction (23-42%) in hemicelluloses while delignification was limited to only 0-12%. These reductions in structural integrity resulted in 20-30% faster hydrolysis rates during anaerobic digestion for the pretreated substrates of straws, sorghum, and corn stover while Douglas fir bark yielded 172% faster hydrolysis/digestion due to its highly refractory nature in the control. Furans and phenolic compounds formed in the pretreated hydrolyzates were below the inhibitory levels for methane and hydrogen production which had a range of 98-340 ml CH 4 /g volatile solids (VS) and 5-26 ml H 2 /g VS, respectively. Results indicated that hydrothermal pretreatment is able to accelerate the rate of biodegradation without generating high levels of inhibitory compounds while showing no discernible effect on ultimate biodegradation. Copyright © 2017 Elsevier Ltd. All rights reserved.

Irradiation of Methane by Recoiling Fission-Fragments

Energy Technology Data Exchange (ETDEWEB)

Hall, G. R.; Galley, M. R. [Imperial College of Science and Technology, London (United Kingdom)

1963-11-15

Pure methane gas (containing <0.003% oxygen and <5 mg H{sub 2}O per m{sup 3}) has been irradiated at pressures ranging from 5 to 50 atmospheres pressure and at 30{sup o}C with recoiling fission - fragments. The gas is contained in a silica ampoule of volume about 9 cm{sup 3} and which also contains a platinum cylinder coated on the inside with 0.5 mg/cm{sup 2} highly enriched uranium oxide. When the ampoule is irradiated in a nuclear reactor with thermal neutrons, about half the fission-fragments recoil from the uranium and dissipate their energy in the methane. In a typical irradiation, methane at 10 atm pressure receives a dose of 5 x 10{sup 21} eV at an integrated reactor flux of 5 x 10{sup 15} neutrons/cm{sup 2}. Neutron flux i s measured by means of a gold-foil flux monitor. The activity of the Au{sup 198} is counted in a 4 {pi} proportional counter. The irradiation products have been detected by using beta-ionization detectors for gas-phase chromatography with suitable columns. The following products have been found: hydrogen, ethane, propane, n-butane, isobutane, n-pentane, iso-pentane, neo-pentane, the seven hexanes. Traces of higher hydrocarbons are undoubtedly present but the analysis of these has not been attempted. Hydrogen is present in greatest yield and the yields of the hydrocarbons decrease in the order given above. Despite previously reported yields of ethylene (G-value-0.1) from gamma and fast - electron irradiations, no ethylene or other unsaturated products have been detected in this work. It would have been possible to detect 10 ppm in the products. This is to be expected as any double bonds which may be produced would almost immediately be hydrogenated by the hydrogen present. Yields for hydrogen, ethane and propane lie within the range of values that have been reported by other workers for gamma and fast electron irradiations. (author)

Biologically Produced Methane as a Renewable Energy Source.

Science.gov (United States)

Holmes, D E; Smith, J A

2016-01-01

Methanogens are a unique group of strictly anaerobic archaea that are more metabolically diverse than previously thought. Traditionally, it was thought that methanogens could only generate methane by coupling the oxidation of products formed by fermentative bacteria with the reduction of CO 2 . However, it has recently been observed that many methanogens can also use electrons extruded from metal-respiring bacteria, biocathodes, or insoluble electron shuttles as energy sources. Methanogens are found in both human-made and natural environments and are responsible for the production of ∼71% of the global atmospheric methane. Their habitats range from the human digestive tract to hydrothermal vents. Although biologically produced methane can negatively impact the environment if released into the atmosphere, when captured, it can serve as a potent fuel source. The anaerobic digestion of wastes such as animal manure, human sewage, or food waste produces biogas which is composed of ∼60% methane. Methane from biogas can be cleaned to yield purified methane (biomethane) that can be readily incorporated into natural gas pipelines making it a promising renewable energy source. Conventional anaerobic digestion is limited by long retention times, low organics removal efficiencies, and low biogas production rates. Therefore, many studies are being conducted to improve the anaerobic digestion process. Researchers have found that addition of conductive materials and/or electrically active cathodes to anaerobic digesters can stimulate the digestion process and increase methane content of biogas. It is hoped that optimization of anaerobic digesters will make biogas more readily accessible to the average person. Copyright © 2016 Elsevier Inc. All rights reserved.

Radiation-induced chemical reaction of methane in the presence of X-and Y-type molecular sieves

International Nuclear Information System (INIS)

Shimizu, Y.; Nagai, S.

1990-01-01

The radiolysis of methane was investigated in the presence of X (13X) and Y (SK-40) type molecular sieves at 300 0 C. Product analysis showed that irradiation of methane over 13X and SK-40 produces hydrogen and hydrocarbons up to C 5 . The yields of hydrocarbons, except for ethylene, over 13X and SK-40 slightly increased with irradiation time. The yields of the main hydrocarbon products over SK-40 were larger than those in the absence of molecular sieve in contrast to those over 13X. It was found that no 13X shows catalytic activity for the radiolysis of methane; on the other hand, SK-40 shows it. The relations between the proportion of hydrocarbon yield of each carbon number to the hydrocarbon total yield over 13X and SK-40 and the carbon number were the same as those in the absence of molecular sieve. It was proved by comparison of these results with those over A-type molecular sieve (5A) that the order of the catalytic activities of the molecular sieves for the radiolysis of methane differs considerably from that found in thermal catalytic reactions. These results are discussed in terms of the concept of energy transfer and the relation between the pore size of the molecular sieves and the molecular diameters of the hydrocarbons produced. (author)

Radiation effects on methane in the presence of molecular sieves

International Nuclear Information System (INIS)

Shimizu, Y.; Nagai, S.; Hatada, M.

1983-01-01

Product analysis has been carried out for the radiation-induced reaction of methane in the presence of molecular sieves (MS) 3A, 4A, 5A and 13X. Irradiation of methane over MS 4A selectively produces C 2 hydrocarbons, while the use of MS 5A leads to C 2 and C 3 hydrocarbons. The selectivity and yields of these hydrocarbons, however, decrease with irradiation time, owing to deposition of carbonaceous solid produced from methane on the surface of the molecular sieves. The carbonaceous solid is decomposed to low-molecular-weight hydrocarbons when irradiated in an H 2 atmosphere. Material balance estimated for the radiation-chemical reaction of argon containing 2 mol% methane over MS 5A reveals that the carbonaceous solid is highly abundant in carbon atoms. On the other hand the formation of carbonaceous solids plays a less important role in the radiation-chemical reaction of methane in the presence of silica gel, which is found to exhibit greater activity for the formation of hydrocarbons than the molecular sieves. (author)

Enhancing methane production of corn stover through a novel way: sequent pretreatment of potassium hydroxide and steam explosion.

Science.gov (United States)

Li, Jianghao; Zhang, Ruihong; Siddhu, Muhammad Abdul Hanan; He, Yanfeng; Wang, Wen; Li, Yeqing; Chen, Chang; Liu, Guangqing

2015-04-01

Getting over recalcitrance of lignocellulose is effective way to fuel production from lignocellulosic biomass. In current work, different pretreatments were applied to enhance the digestibility of corn stover (CS). Results showed that steam explosion (SE)-treated CS produced maximal methane yield (223.2 mL/gvs) at 1.2 MPa for 10 min, which was 55.2% more than untreated (143.8 mL/gvs). Whereas 1.5% KOH-treated CS produced maximum methane yield of 208.6 mL/gvs, and significantly (αpotassium hydroxide and steam explosion (SPPE) (1.5% KOH-1.2 MPa, 10 min) achieved a very significant (α<0.01) improvement (80.0%) of methane yield (258.8 mL/gvs) compared with untreated CS. Methane production could be well explained by the first-order and modified Gompertz models. Besides, SEM, FTIR, and XRD analyses validated structural changes of CS after SPPE. SPPE might be a promising method to pretreat CS in the future AD industry. Copyright © 2015 Elsevier Ltd. All rights reserved.

Microbial characteristics analysis and kinetic studies on substrate composition to methane after microbial and nutritional regulation of fruit and vegetable wastes anaerobic digestion.

Science.gov (United States)

Zhao, Chunhui; Mu, Hui; Zhao, Yuxiao; Wang, Liguo; Zuo, Bin

2018-02-01

This study firstly evaluated the microbial role when choosing the acclimated anaerobic granular sludge (AGS) and waste activated sludge (WAS) as microbial and nutritional regulators to improve the biomethanation of fruit and vegetable wastes (FVW). Results showed that the enriched hydrogenotrophic methanogens, and Firmicutes and Spirochaeta in the AGS were responsible for the enhanced methane yield. A synthetic waste representing the mixture of WAS and FVW was then used to investigate the influences of different substrate composition on methane generations. The optimal mass ratio of carbohydrate/protein/cellulose was observed to be 50:45:5, and the corresponding methane yield was 411mL/g-VS added . Methane kinetic studies suggested that the modified Gompertz model fitted better with those substrates of carbohydrate- than protein-predominated. Parameter results indicated that the maximum methane yield and production rate were enhanced firstly and then reduced with the decreasing carbohydrate and increasing protein percentages; the lag phase time however increased continuously. Copyright © 2017 Elsevier Ltd. All rights reserved.

Methane synthesis under mild conditions for decentralized applications

International Nuclear Information System (INIS)

Schlueter, Michael; Roensch, Stefan

2016-01-01

It is a central aim of the German government to significantly reduce the emission of greenhouse gases in the next years. One possibility to reach this aim is the substitution of fossil fuels, especially natural gas, by fuels from biogenic sources (Bio-SNG). However, it is a drawback of Bio-SNG that the production costs are considerably higher than those of fossil natural gas. This work provides an approach to reduce the production costs of Bio-SNG. It is the aim to reduce the process parameters of the methane synthesis. At the same time, it has to be ensured that high methane yields are achieved even at those mild conditions. A procedure for the optimization of the methanation catalyst activity will be presented. If the catalyst is as active as possible even at mild conditions, it will be possible to produce Bio-SNG cost efficient even in small, decentralized scale.

Reaction-transport simulations of non-oxidative methane conversion with continuous hydrogen removal: Homogeneous-heterogeneous methane reaction pathways

International Nuclear Information System (INIS)

Li, Lin; Borry, Richard W.; Iglesia, Enrique

2000-01-01

Detailed kinetic-transport models were used to explore thermodynamic and kinetic barriers in the non-oxidative conversion of CH4 via homogeneous and homogeneous-heterogeneous pathways and the effects of continuous hydrogen removal and of catalytic sites on attainable yields of useful C2-C10 products. The homogeneous kinetic model combines separately developed models for low-conversion pyrolysis and for chain growth to form large aromatics and carbon. The H2 formed in the reaction decreases CH4 pyrolysis rates and equilibrium conversions and it favors the formation of lighter products. The removal of H2 along tubular reactors with permeable walls increases reaction rates and equilibrium CH4 conversions. C2-C10 yields reach values greater than 90 percent at intermediate values of dimensionless transport rates (delta=1-10), defined as the ratio hydrogen transport and methane conversion rates. Homogeneous reactions require impractical residence times, even with H2 removal, because of slow initiation and chain transfer rates. The introduction of heterogeneous chain initiation pathways using surface sites that form methyl radicals eliminates the induction period without influencing the homogeneous product distribution. Methane conversion, however, occurs predominately in the chain transfer regime, within which individual transfer steps and the formation of C2 intermediates become limited by thermodynamic constraints. Catalytic sites alone cannot overcome these constraints. Catalytic membrane reactors with continuous H2 removal remove these thermodynamic obstacles and decrease the required residence time. Reaction rates become limited by homogeneous reactions of C2 products to form C6+ aromatics. Higher delta values lead to subsequent conversion of the desired C2-C10 products to larger polynuclear aromatics. We conclude that catalytic methane pyrolysis at the low temperatures required for restricted chain growth and the elimination of thermodynamics constraints via

Employing response surface methodology (RSM) to improve methane production from cotton stalk.

Science.gov (United States)

Zhang, Han; Khalid, Habiba; Li, Wanwu; He, Yanfeng; Liu, Guangqing; Chen, Chang

2018-03-01

China is the largest cotton producer with the cotton output accounting for 25% of the total world's cotton production. A large quantity of cotton stalk (CS) waste is generated which is burned and causes environmental and ecological problems. This study investigated the anaerobic digestibility of CS by focusing on improving the methane yield by applying central composite design of response surface methodology (RSM). The purpose of this study was to determine the best level of factors to optimize the desired output of methane production from CS. Thus, it was necessary to describe the relationship of many individual variables with one or more response values for the effective utilization of CS. The influences of feed to inoculum (F/I) ratio and organic loading (OL) on methane production were investigated. Results showed that the experimental methane yield (EMY) and volatile solid (VS) removal were calculated to be 70.22 mL/gVS and 14.33% at F/I ratio of 0.79 and organic loading of 25.61 gVS/L, respectively. Characteristics of final effluent showed that the anaerobic system was stable. This research laid a foundation for future application of CS to alleviate the problems of waste pollution and energy output.

MethaneSat: Detecting Methane Emissions in the Barnett Shale Region

Science.gov (United States)

Propp, A. M.; Benmergui, J. S.; Turner, A. J.; Wofsy, S. C.

2017-12-01

In this study, we investigate the new information that will be provided by MethaneSat, a proposed satellite that will measure the total column dry-air mole fraction of methane at 1x1 km or 2x2 km spatial resolution with 0.1-0.2% random error. We run an atmospheric model to simulate MethaneSat's ability to characterize methane emissions from the Barnett Shale, a natural gas province in Texas. For comparison, we perform observation system simulation experiments (OSSEs) for MethaneSat, the National Oceanic and Atmospheric administration (NOAA) surface and aircraft network, and Greenhouse Gases Observing Satellite (GOSAT). The results demonstrate the added benefit that MethaneSat would provide in our efforts to monitor and report methane emissions. We find that MethaneSat successfully quantifies total methane emissions in the region, as well as their spatial distribution and steep gradients. Under the same test conditions, both the NOAA network and GOSAT fail to capture this information. Furthermore, we find that the results for MethaneSat depend far less on the prior emission estimate than do those for the other observing systems, demonstrating the benefit of high sampling density. The results suggest that MethaneSat would be an incredibly useful tool for obtaining detailed methane emission information from oil and gas provinces around the world.

Enhanced coproduction of hydrogen and methane from cornstalks by a three-stage anaerobic fermentation process integrated with alkaline hydrolysis.

Science.gov (United States)

Cheng, Xi-Yu; Liu, Chun-Zhao

2012-01-01

A three-stage anaerobic fermentation process including H(2) fermentation I, H(2) fermentation II, methane fermentation was developed for the coproduction of hydrogen and methane from cornstalks. Hydrogen production from cornstalks using direct microbial conversion by Clostridium thermocellum 7072 was markedly enhanced in the two-stage thermophilic hydrogen fermentation process integrated with alkaline treatment. The highest total hydrogen yield from cornstalks in the two-stage fermentation process reached 74.4 mL/g-cornstalk. The hydrogen fermentation effluents and alkaline hydrolyzate were further used for methane fermentation by anaerobic granular sludge, and the total methane yield reached 205.8 mL/g-cornstalk. The total energy recovery in the three-stage anaerobic fermentation process integrated with alkaline hydrolysis reached 70.0%. Copyright © 2011 Elsevier Ltd. All rights reserved.

Methane Production in Microbial Reverse-Electrodialysis Methanogenesis Cells (MRMCs) Using Thermolytic Solutions

KAUST Repository

Luo, Xi

2014-08-05

The utilization of bioelectrochemical systems for methane production has attracted increasing attention, but producing methane in these systems requires additional voltage to overcome large cathode overpotentials. To eliminate the need for electrical grid energy, we constructed a microbial reverse- electrodialysis methanogenesis cell (MRMC) by placing a reverse electrodialysis (RED) stack between an anode with exoelectrogenic microorganisms and a methanogenic biocathode. In the MRMC, renewable salinity gradient energy was converted to electrical energy, thus providing the added potential needed for methane evolution from the cathode. The feasibility of the MRMC was examined using three different cathode materials (stainless steel mesh coated with platinum, SS/Pt; carbon cloth coated with carbon black, CC/CB; or a plain graphite fiber brush, GFB) and a thermolytic solution (ammonium bicarbonate) in the RED stack. A maximum methane yield of 0.60 ± 0.01 mol-CH 4/mol-acetate was obtained using the SS/Pt biocathode, with a Coulombic recovery of 75 ± 2% and energy efficiency of 7.0 ± 0.3%. The CC/CB biocathode MRMC had a lower methane yield of 0.55 ± 0.02 mol-CH4/mol-acetate, which was twice that of the GFB biocathode MRMC. COD removals (89-91%) and Coulombic efficiencies (74-81%) were similar for all cathode materials. Linear sweep voltammetry and electrochemical impedance spectroscopy tests demonstrated that cathodic microorganisms enhanced electron transfer from the cathode compared to abiotic controls. These results show that the MRMC has significant potential for production of nearly pure methane using low-grade waste heat and a source of waste organic matter at the anode. © 2014 American Chemical Society.

Waste valorization and bio-methanization in urban areas. The Strasbourg-La Wantzenau treatment plant: transformation of wastewaters into natural gas

International Nuclear Information System (INIS)

Sourdril, Antoine; Izambart, Geraldine; Pellerin, Bruno; Meyer, Walter

2017-01-01

This document contains two articles reporting visits to two waste-to-energy valorization plants: the first one, located in Liege (Belgium), comprises an energy valorization plant for municipal wastes and a bio-methanization unit (under construction) for organic wastes which will open in 2019. The second one, located in Strasbourg (France), is a wastewater treatment plant (69 millions m 3 per year) producing 5000 tonnes of sludges, a part of which (Biovalsan project) are introduced into two digesters for the ultimate production of biogas (containing about 62 pc of methane). The volume of bio-methane will cover the needs of 5000 households in the Strasbourg area

Influence of variable feeding on mesophilic and thermophilic co-digestion of Laminaria digitata and cattle manure

International Nuclear Information System (INIS)

Sarker, Shiplu; Møller, Henrik Bjarne; Bruhn, Annette

2014-01-01

Highlights: • Anaerobic co-digestion of L. digitata and cattle manure, at ∼35 and ∼50 °C. • Mesophilic co-digestion showed somewhat stable specific methane, but increased volumetric yield. • Thermophilic co-digester yielded higher methane at higher input of algae compared to control. • Mesophilic co-digester performed better in terms of various parameters except methane yield. - Abstract: In this study the effect of various feeding ratios on mesophilic (∼35 °C) and thermophilic (∼50 °C) co-digestion of brown algae Laminaria digitata and cattle manure was investigated. Algae input of 15% VS caused no influence on specific methane yield from mesophilic co-digester while deteriorated the process parameters such as the development of propionic acid in total volatile fatty acids (tVFA) pattern of the thermophilic co-digester. The accumulation of tVFA continued for the latter reactor as the feeding ratio of algae enhanced to 24% VS, but the specific methane yield improved dramatically. Same rise in feeding once again showed no improvement in specific methane yield from mesophilic co-digester even though the other process parameters stabilized or, enriched such as the gain in average volumetric methane yield. For the last feeding ratio at 41% VS algae, specific methane yield from mesophilic co-digester slightly increased which however was not still comparable with the ultimate methane yield from the cattle manure alone. The thermophilic co-digestion on the other hand yielded maximum specific methane, together with the improvement in different process characteristics, as the feeding of algae maximized at the final stage. The trend of methane production from this reactor nevertheless was sharply downward towards the end of the experiment suggesting that the optimum feeding ratio has already been achieved for the present experimental conditions

Increasing the biogas yield of manure by wet explosion of the digested fiber fraction

DEFF Research Database (Denmark)

Biswas, Rajib; Uellendahl, Hinrich; Ahring, Birgitte Kiær

digested manure fibers from the effluent of an anaerobic digester for enhancing biogas production and exploring the untapped biomass potential. The increase in methane yield of the digested manure fibers was investigated by applying the WEx treatment under 5 different process conditions. The pretreatment......Increasing the biodegradability of the lignocellulosic fiber fraction of manure can ensure higher methane productivity in biogas plants, leading to process profitability and thus larger production of renewable energy. A new pretreatment method, wet explosion (WEx), was investigated to treat...... condition of 180 ºC and a retention time of 10 minutes without addition of chemicals was found to be optimal, resulting in 136% increase in methane yield as compared to the untreated digested manure fibers....

How Does Poly(hydroxyalkanoate) Affect Methane Production from the Anaerobic Digestion of Waste-Activated Sludge?

Science.gov (United States)

Wang, Dongbo; Zhao, Jianwei; Zeng, Guangming; Chen, Yinguang; Bond, Philip L; Li, Xiaoming

2015-10-20

Recent studies demonstrate that, besides being used for production of biodegradable plastics, poly(hydroxyalkanoate) (PHA) that is accumulated in heterotrophic microorganisms during wastewater treatment has another novel application direction, i.e., being utilized for enhancing methane yield during the anaerobic digestion of waste-activated sludge (WAS). To date, however, the underlying mechanism of how PHA affects methane production remains largely unknown, and this limits optimization and application of the strategy. This study therefore aims to fill this knowledge gap. Experimental results showed that with the increase of sludge PHA levels from 21 to 184 mg/g of volatile suspended solids (VSS) the methane yield linearly increased from 168.0 to 246.1 mL/g of VSS (R(2) = 0.9834). Compared with protein and carbohydrate (the main components of a cell), PHA exhibited a higher biochemical methane potential on a unit VSS basis. It was also found that the increased PHA not only enhanced cell disruption of PHA cells but also benefited the soluble protein conversion of both PHA- and non-PHA cells. Moreover, the reactor fed with higher PHA sludge showed greater sludge hydrolysis and acidification than those fed with the lower PHA sludges. Further investigations using fluorescence in situ hybridization and enzyme analysis revealed that the increased PHA enhanced the abundance of methanogenic Archaea and increased the activities of protease, acetate kinase, and coenzyme F420, which were consistent with the observed methane yield. This work provides insights into PHA-involved WAS digestion systems and may have important implications for future operation of wastewater treatment plants.

Produção volumétrica de metano: dejetos de suínos Methane volumetric yield: swine wastes

Directory of Open Access Journals (Sweden)

Cecília de Fátima Souza

2008-02-01

Full Text Available O presente trabalho foi conduzido para avaliar o potencial de produção de biogás de dejetos de suínos, especificamente a produção de metano. O substrato, no qual a concentração de sólidos totais foi de 6%, foi composto por dejeto sólido diluído em água. Os dejetos foram coletados por raspagem, em instalações de terminação de suínos, compostas de baias, com paredes de alvenaria de tijolos e piso de cimento. Os suínos experimentais receberam ração balanceada à base de milho e soja. O sistema de tratamento, em escala laboratorial, foi composto por três baterias com oito biodigestores em cada, instalados dentro de caixas de cimento amianto de 500 litros, contendo 270 litros de água aquecida. Em cada caixa, uma resistência elétrica e uma bomba d'água foram instaladas para manter a temperatura e misturar a água aquecida. O sistema foi submetido a Tempos de Retenção Hidráulica (TRH de 30, 25, 15 e 10 dias e a temperaturas de 25, 35 e 40 ºC, com e sem agitação do substrato. Foi avaliado, nessas condições, o processo de degradação da matéria orgânica e a produção resultante de metano (PM. Os maiores valores de PM foram observados nos TRH de 10 dias, à temperatura de 40 ºC, nos biodigestores com agitação do substrato.The present work was carried out to evaluate the swine wastes biogas potential yield, specifically the methane yield. The total solid content in the substratum was 6% composed by the solid waste diluted to water. The wastes was collected by scratching, in swine ending facilities, composed by boxes, in which the walls were constructed of masonry and the floor was constructed of cement. The experimental swines received corn and soybean balanced ration. The waste treatment system, in laboratorial scale, was composed by three batteries with eight digesters each, installed inside of 500 liters asbestos boxes, containing 270 liters of heated water. In each box, an eletric resistance and water pump were

Characterization of Methane Degradation and Methane-Degrading Microbes in Alaska Coastal Water

Energy Technology Data Exchange (ETDEWEB)

Kirchman, David L. [Univ. of Delaware, Lewes, DE (United States)

2012-03-29

The net flux of methane from methane hydrates and other sources to the atmosphere depends on methane degradation as well as methane production and release from geological sources. The goal of this project was to examine methane-degrading archaea and organic carbon oxidizing bacteria in methane-rich and methane-poor sediments of the Beaufort Sea, Alaska. The Beaufort Sea system was sampled as part of a multi-disciplinary expedition (Methane in the Arctic Shelf or MIDAS) in September 2009. Microbial communities were examined by quantitative PCR analyses of 16S rRNA genes and key methane degradation genes (pmoA and mcrA involved in aerobic and anaerobic methane degradation, respectively), tag pyrosequencing of 16S rRNA genes to determine the taxonomic make up of microbes in these sediments, and sequencing of all microbial genes (metagenomes ). The taxonomic and functional make-up of the microbial communities varied with methane concentrations, with some data suggesting higher abundances of potential methane-oxidizing archaea in methane-rich sediments. Sequence analysis of PCR amplicons revealed that most of the mcrA genes were from the ANME-2 group of methane oxidizers. According to metagenomic data, genes involved in methane degradation and other degradation pathways changed with sediment depth along with sulfate and methane concentrations. Most importantly, sulfate reduction genes decreased with depth while the anaerobic methane degradation gene (mcrA) increased along with methane concentrations. The number of potential methane degradation genes (mcrA) was low and inconsistent with other data indicating the large impact of methane on these sediments. The data can be reconciled if a small number of potential methane-oxidizing archaea mediates a large flux of carbon in these sediments. Our study is the first to report metagenomic data from sediments dominated by ANME-2 archaea and is one of the few to examine the entire microbial assemblage potentially involved in

Improving anaerobic digestion of sugarcane straw for methane production: Combined benefits of mechanical and sodium hydroxide pretreatment for process designing

International Nuclear Information System (INIS)

Janke, Leandro; Weinrich, Sören; Leite, Athaydes F.; Terzariol, Filippi K.; Nikolausz, Marcell; Nelles, Michael; Stinner, Walter

2017-01-01

Highlights: • NaOH pretreatment was tested to improve degradation of SCS for methane production. • Low NaOH concentration accelerated AD of SCS but not increased the methane yield. • Mild and high NaOH concentrations accelerated and increased methane yield of SCS. • NaOH use increased OPEX but provided a higher profitability than the untreated SCS. • Anaerobic reactor price showed a high influence on sensitivity analysis. - Abstract: Sodium hydroxide (NaOH) as an alkaline pretreatment method to enhance the degradation kinetics of sugarcane straw (SCS) for methane production was investigated with a special focus on the benefits for designing the anaerobic digestion process. For that, SCS was previously homogenized by milling in 2 mm particle size and pretreated in NaOH solutions at various concentrations (0, 3, 6 and 12 g NaOH/100 g SCS) and the methane yields were determined in biochemical methane potential (BMP) tests. The obtained experimental data were used to simulate a large-scale semi-continuous process (100 ton SCS day"−"1) according to a first-order reaction model and the main economic indicators were calculated based on cash flows of each pretreatment condition. The BMP tests showed that by increasing the NaOH concentration the conversion of the fibrous fraction of the substrate to methane was not only accelerated (higher α value), but also increased by 11.9% (from 260 to 291 mL CH_4 gVS"−"1). By using the experimental data to simulate the large-scale process these benefits were translated to a reduction of up to 58% in the size of the anaerobic reactor (and consequently in electricity consumption for stirring), while the methane yield increased up to 28%, if the liquid fraction derived from the pretreatment process is also used for methane production. Although the use of NaOH for substrate pretreatment has considerably increased the operational expenditures (from 0.97 up to 1.97 € × 10"6 year"−"1), the pretreatment method was able to

Two phases fermentative process for hydrogen and methane production from cassava wastewater

Directory of Open Access Journals (Sweden)

Aryane Mota Oliveira

2017-04-01

Full Text Available Introduction: Hydrogen and methane production was investigated in two phases of fermentative process. Objective: At the acidogenic phase, an anaerobic fluidized bed reactor was fed with cassava wastewater producing hydrogen. Methods: Expanded clay was used as a support material for biomass immobilization. The reactor was operated with HRT ranging from 8-1 h. Results: The best hydrogen yield production was 1.91 mol H2/mol glucose at HRT of 2 h. At the methanogenic phase, the acidogenic process effluent fed a fixed-bed reactor producing methane. Conclusion: Sururu (Mytella falcata shells was used as support acted as pH neutralizer in the fixed-bed reactor, yielding best (0.430±0.150 Lmethane/gCOD with 12h HRT phase.

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 direct aromatization of methane

Energy Technology Data Exchange (ETDEWEB)

Marcelin, G.; Oukaci, R.; Migone, R.A.; Kazi, A.M. [Altamira Instruments, Pittsburgh, PA (United States)

1995-12-31

The thermal decomposition of methane shows significant potential as a process for the production of higher unsaturated and aromatic hydrocarbons when the extent of the reaction is limited. Thermodynamic calculations have shown that when the reaction is limited to the formation of C{sub 2} to C{sub 10} products, yields of aromatics can exceed 40% at temperatures of 1200{degrees}C. Preliminary experiments have shown that when the reaction is limited to the formation of C{sub 2} to C{sub 10} products, yields of aromatics can exceed 40% at temperatures of 1200{degrees}C. Preliminary experiments have shown that cooling the product and reacting gases as the reaction proceeds can significantly reduce or eliminate the formation of solid carbon and heavier (C{sub 10+}) materials. Much work remains to be done in optimizing the quenching process and this is one of the goals of this program. Means to lower the temperature of the reaction are being studied as this result in a more feasible commercial process due to savings realized in energy and material of construction costs. The use of free-radical generators and catalysts will be investigated as a means of lowering the reaction temperature thus allowing faster quenching. It is highly likely that such studies will lead to a successful direct methane to higher hydrocarbon process.

Methane Recycling During Burial of Methane Hydrate-Bearing Sediments

Science.gov (United States)

You, K.; Flemings, P. B.

2017-12-01

We quantitatively investigate the integral processes of methane hydrate formation from local microbial methane generation, burial of methane hydrate with sedimentation, and methane recycling at the base of the hydrate stability zone (BHSZ) with a multiphase multicomponent numerical model. Methane recycling happens in cycles, and there is not a steady state. Each cycle starts with free gas accumulation from hydrate dissociation below the BHSZ. This free gas flows upward under buoyancy, elevates the hydrate saturation and capillary entry pressure at the BHSZ, and this prevents more free gas flowing in. Later as this layer with elevated hydrate saturation is buried and dissociated, the large amount of free gas newly released and accumulated below rapidly intrudes into the hydrate stability zone, drives rapid hydrate formation and creates three-phase (gas, liquid and hydrate) equilibrium above the BHSZ. The gas front retreats to below the BHSZ until all the free gas is depleted. The shallowest depth that the free gas reaches in one cycle moves toward seafloor as more and more methane is accumulated to the BHSZ with time. More methane is stored above the BHSZ in the form of concentrated hydrate in sediments with relatively uniform pore throat, and/or with greater compressibility. It is more difficult to initiate methane recycling in passive continental margins where the sedimentation rate is low, and in sediments with low organic matter content and/or methanogenesis reaction rate. The presence of a permeable layer can store methane for significant periods of time without recycling. In a 2D system where the seafloor dips rapidly, the updip gas flow along the BHSZ transports more methane toward topographic highs where methane gas and elevated hydrate saturation intrude deeper into the hydrate stability zone within one cycle. This could lead to intermittent gas venting at seafloor at the topographic highs. This study provides insights on many phenomenon associated with

Parametric study on catalytic tri-reforming of methane for syngas production

International Nuclear Information System (INIS)

Chein, Rei-Yu; Wang, Chien-Yu; Yu, Ching-Tsung

2017-01-01

A two-dimensional numerical model for syngas production from tri-reforming of methane (TRM) in adiabatic tubular fixed-bed reactors was established. From the results obtained, it was found that reactant must be preheated to certain temperatures for TRM activation. Although the delay factor accounting for the varying catalytic bed activities produced different temperature and species mole fraction profiles in the reactor upstream, the reactor performance was delay factor independent if the reactor outlet results were used because nearly identical temperature and species mole fraction variations were obtained at the reactor downstream. The numerical results also indicated that reverse water-gas shift reaction plays an important role for H 2 and CO yields. With higher O 2 in reactant, high temperature resulted, leading to lower H 2 /CO ratio. The absence of H 2 O in the reactant caused dry reforming of methane as the dominant reaction, resulting in H 2 /CO ratio close to unity. With the absence of CO 2 in the reactant, steam reforming of methane was the dominant reaction, resulting in H 2 /CO ratio close to 3. Using flue gas from combustion as TRM feedstock, it was found that H 2 /CO ratio was enhanced using lower CH 4 amount in reactant. High-temperature flue gas was suggested for TRM for the activation requirement. - Highlights: • Reactant must be preheated to certain temperature for tri-reforming of methane (TRM) activation. • A delay factor is used to account for varying catalytic activity. • TRM performance is delay factor independent when reactor outlet results are used. • Water-gas shift reaction plays an important role in H 2 yield, CO yield and H 2 /CO ratio in TRM. • Low CH 4 and high temperature are suggested when flue gas is used in TRM.

Methane and carbon dioxide production from simulated anaerobic degradation of cattle carcasses

International Nuclear Information System (INIS)

Yuan Qi; Saunders, Samuel E.; Bartelt-Hunt, Shannon L.

2012-01-01

Highlights: ► This study evaluates methane and carbon dioxide production after land burial of cattle carcasses. ► Disposal of animal mortalities is often overlooked in evaluating the environmental impacts of animal production. ► we quantify annual emissions from cattle carcass disposal in the United States as 1.6 Tg CO 2 equivalents. - Abstract: Approximately 2.2 million cattle carcasses require disposal annually in the United States. Land burial is a convenient disposal method that has been widely used in animal production for disposal of both daily mortalities as well as during catastrophic mortality events. To date, greenhouse gas production after mortality burial has not been quantified, and this study represents the first attempt to quantify greenhouse gas emissions from land burial of animal carcasses. In this study, anaerobic decomposition of both homogenized and unhomogenized cattle carcass material was investigated using bench-scale reactors. Maximum yields of methane and carbon dioxide were 0.33 and 0.09 m 3 /kg dry material, respectively, a higher methane yield than that previously reported for municipal solid waste. Variability in methane production rates were observed over time and between reactors. Based on our laboratory data, annual methane emissions from burial of cattle mortalities in the United States could total 1.6 Tg CO 2 equivalents. Although this represents less than 1% of total emissions produced by the agricultural sector in 2009, greenhouse gas emissions from animal carcass burial may be significant if disposal of swine and poultry carcasses is also considered.

Evaluation Of Yield And Chemical Properties Of Some Faba Bean (Vicia FABA L.) Mutants Induced By GAMMA Radiation And Ethyl Methane Sulphonate

International Nuclear Information System (INIS)

Sallam, E.M.; Nasr, E.H.; Attia, Z.M.; Shawki, H.A.

2013-01-01

This investigation aims to study the effect of physical and chemical mutagens on the yield and chemical properties as well as amino acids composition of defatted faba bean (Vicia faba L.) seeds meal as a control (Giza 2) compared with mutants produced by gamma radiation and ethyl methane sulphonate (EMS). Also, the functional properties of these samples were determined. The results indicated high differences between mutation for seed yield and its components than the untreated samples. In addition, radiation mutation of faba bean seeds showed slight increase in protein content as the main constituent of faba bean seeds as well as total oil percentages in some mutant of these seeds in return of decreasing in total carbohydrate. Furthermore, radiation mutation had detectable effects on the total amino acids contents of faba bean seeds meal which had a higher percentages on essential amino acids (EAA) and non-essential amino acids (NEAA) and mutant 3 was the highest values of EAA and NEAA as compared to the control. On the other hand, radiation mutation improved the protein functional properties of some mutant of faba bean meal flour than the other mutant samples as compared to local commercial variety

Stalking the ultimate particle

CERN Multimedia

2003-01-01

If you missed the ARTE programme entitled "L'Ultime Particule" broadcast in February, you have another chance to catch it in CERN's Main Auditorium on 13 March. "L'Ultime Particule" is a documentary by the French director Michel Andrieu that seeks to explain particle physics through a contemplative quest for the research physicists of matter of today and yesteryear. Invariably kitted out in a red parka and a soft hat, the programme's investigator scours the planet and the archives in search of the research physicists who are stalking the ultimate particle, the Higgs boson, in their quest to understand the structure of matter. Naturally enough, CERN is an important stage of his journey where Michel Andrieu and his team spent several days last year. Both from the physics and metaphysical points of view, "L'Ultime Particule" is worth seeing. The film's director, Michel Andrieu, will introduce his documentary and answer questions from the audience after the documentary has been shown. L'Ultime Particule by Mic...

Anaerobic treatment of cassava stillage for hydrogen and methane production in continuously stirred tank reactor (CSTR) under high organic loading rate (OLR)

Energy Technology Data Exchange (ETDEWEB)

Luo, Gang; Xie, Li; Zou, Zhonghai; Wang, Wen; Zhou, Qi [Key Laboratory of Yangtze River Water Environment, Ministry of Education (Tongji University), UNEP-Tongji, Tongji University, Siping Road No. 1239, Shanghai 200092 (China); Shim, Hojae [Department of Civil and Environmental Engineering, Faculty of Science and Technology, University of Macau, Macau SAR 999078 (China)

2010-11-15

Anaerobic hydrogen and methane production from cassava stillage in continuously stirred tank reactor (CSTR) were investigated in this study. Results showed that the heat-pretreatment of inoculum did not enhance hydrogen yield compared to raw inoculum under mesophilic condition after continuous operation. However, the hydrogen yield increased from about 14 ml H{sub 2}/gVS under mesophilic condition to 69.6 ml H{sub 2}/gVS under thermophilic condition due to the decrease of propionate concentration and inhibition of homoacetogens. Therefore, temperature was demonstrated to be more important than pretreatment of inoculum to enhance the hydrogen production. Under high organic loading rate (OLR) (>10 gVS/(L.d)), the two-phase thermophilic CSTR for hydrogen and methane production was stable with hydrogen and methane yields of 56.6 mlH{sub 2}/gVS and 249 mlCH{sub 4}/gVS. The one-phase thermophilic CSTR for methane production failed due to the accumulation of both acetate and propionate, leading to the pH lower than 6. Instead of propionate alone, the accumulations of both acetate and propionate were found to be related to the breakdown of methane reactor. (author)

Methanation of CO2 over Zeolite-Encapsulated Nickel Nanoparticles

DEFF Research Database (Denmark)

Goodarzi, Farnoosh; Kang, Liqun; Wang, Feng Ryan

2018-01-01

in an increased metal dispersion and, consequently, a high catalytic activity for CO2 methanation. With a gas hourly space velocity of 60000 ml/g catalyst h-1 and H2/CO2=4, the zeolite-encapsulated Ni nanoparticles result in 60% conversion at 450°C, which corresponds to a site-time yield of around 304 mol CH4/mol......Efficient methanation of CO2 relies on the development of more selective and stable heterogeneous catalysts. Here we present a simple and effective method to encapsulate Ni nanoparticles in zeolite silicalite-1. In this method, the zeolite is modified by selective desilication, which creates intra...

Production of methane by co-digestion of cassava pulp with various concentrations of pig manure

Energy Technology Data Exchange (ETDEWEB)

Panichnumsin, Pornpan [The Joint Graduate School of Energy and Environment, King Mongkut' s University of Technology Thonburi, Thungkru, Bangkok 10140 (Thailand); Excellent Center of Waste Utilization and Management, National Center for Genetic Engineering and Biotechnology, Bangkhuntien, Bangkok 10150 (Thailand); Nopharatana, Annop [Pilot Plant Development and Training Institute, King Mongkut' s University of Technology Thonburi, Bangkhuntien, Bangkok 10150 (Thailand); Ahring, Birgitte [AAU, Copenhagen Institute of Technology, Lautrupvang 15, 2750 Ballerup (Denmark); Chaiprasert, Pawinee [School of Bioresources and Technology, King Mongkut' s University of Technology Thonburi, Bangkhuntien, Bangkok 10150 (Thailand)

2010-08-15

Cassava pulp is a major by-product produced in a cassava starch factory, containing 50-60% of starch (dry basis). Therefore, in this study we are considering its potential as a raw material substrate for the production of methane. To ensure sufficient amounts of nutrients for the anaerobic digestion process, the potential of co-digestion of cassava pulp (CP) with pig manure (PM) was further examined. The effect of the co-substrate mixture ratio was carried out in a semi-continuously fed stirred tank reactor (CSTR) operated under mesophilic condition (37 C) and at a constant OLR of 3.5 kg VS m{sup -3} d{sup -1} and a HRT of 15 days. The results showed that co-digestion resulted in higher methane production and reduction of volatile solids (VS) but lower buffering capacity. Compared to the digestion of PM alone, the specific methane yield increased 41% higher when co-digested with CP in concentrations up to 60% of the incoming VS. This was probably due to an increase in available easily degradable carbohydrates as the CP ratio in feedstock increased. The highest methane yield and VS removal of 306 mL g{sup -1} VS{sub added} and 61%, respectively, were achieved with good process stability (VFA:Alkalinity ratio < 0.1) when CP accounted for 60% of the feedstock VS. A further increase of CP of the feedstock led to a decrease in methane yield and solid reductions. This appeared to be caused by an extremely high C:N ratio of the feedstock resulting in a deficiency of ammonium nitrogen for microbial growth and buffering capacity. (author)

Production of methane by co-digestion of cassava pulp with various concentrations of pig manure

International Nuclear Information System (INIS)

Panichnumsin, Pornpan; Nopharatana, Annop; Ahring, Birgitte; Chaiprasert, Pawinee

2010-01-01

Cassava pulp is a major by-product produced in a cassava starch factory, containing 50-60% of starch (dry basis). Therefore, in this study we are considering its potential as a raw material substrate for the production of methane. To ensure sufficient amounts of nutrients for the anaerobic digestion process, the potential of co-digestion of cassava pulp (CP) with pig manure (PM) was further examined. The effect of the co-substrate mixture ratio was carried out in a semi-continuously fed stirred tank reactor (CSTR) operated under mesophilic condition (37 o C) and at a constant OLR of 3.5 kg VS m -3 d -1 and a HRT of 15 days. The results showed that co-digestion resulted in higher methane production and reduction of volatile solids (VS) but lower buffering capacity. Compared to the digestion of PM alone, the specific methane yield increased 41% higher when co-digested with CP in concentrations up to 60% of the incoming VS. This was probably due to an increase in available easily degradable carbohydrates as the CP ratio in feedstock increased. The highest methane yield and VS removal of 306 mL g -1 VS added and 61%, respectively, were achieved with good process stability (VFA:Alkalinity ratio < 0.1) when CP accounted for 60% of the feedstock VS. A further increase of CP of the feedstock led to a decrease in methane yield and solid reductions. This appeared to be caused by an extremely high C:N ratio of the feedstock resulting in a deficiency of ammonium nitrogen for microbial growth and buffering capacity.

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.

METHANE STEAM REACTION OVER NICKEL CATALYSTS IN THE HYNOL PROCESS

Science.gov (United States)

The report discusses the reaction of methane-steam over nickel catalysts in the Hynol process, a process that uses biomass and natural gas as feedstocks to maximize methanol yields and minimize greenhouse gas emissions. EPA's APPCD has established a laboratory in which to conduct...

Mild oxidation of methane to methanol or acetic acid on supported isolated rhodium catalysts

Science.gov (United States)

Shan, Junjun; Li, Mengwei; Allard, Lawrence F.; Lee, Sungsik; Flytzani-Stephanopoulos, Maria

2017-11-01

An efficient and direct method of catalytic conversion of methane to liquid methanol and other oxygenates would be of considerable practical value. However, it remains an unsolved problem in catalysis, as typically it involves expensive or corrosive oxidants or reaction media that are not amenable to commercialization. Although methane can be directly converted to methanol using molecular oxygen under mild conditions in the gas phase, the process is either stoichiometric (and therefore requires a water extraction step) or is too slow and low-yielding to be practical. Methane could, in principle, also be transformed through direct oxidative carbonylation to acetic acid, which is commercially obtained through methane steam reforming, methanol synthesis, and subsequent methanol carbonylation on homogeneous catalysts. However, an effective catalyst for the direct carbonylation of methane to acetic acid, which might enable the economical small-scale utilization of natural gas that is currently flared or stranded, has not yet been reported. Here we show that mononuclear rhodium species, anchored on a zeolite or titanium dioxide support suspended in aqueous solution, catalyse the direct conversion of methane to methanol and acetic acid, using oxygen and carbon monoxide under mild conditions. We find that the two products form through independent pathways, which allows us to tune the conversion: three-hour-long batch-reactor tests conducted at 150 degrees Celsius, using either the zeolite-supported or the titanium-dioxide-supported catalyst, yield around 22,000 micromoles of acetic acid per gram of catalyst, or around 230 micromoles of methanol per gram of catalyst, respectively, with selectivities of 60-100 per cent. We anticipate that these unusually high activities, despite still being too low for commercial application, may guide the development of optimized catalysts and practical processes for the direct conversion of methane to methanol, acetic acid and other useful

Catalytic generation of methane at 60-100 °C and 0.1-300 MPa from source rocks containing kerogen Types I, II, and III

Science.gov (United States)

Wei, Lin; Schimmelmann, Arndt; Mastalerz, Maria; Lahann, Richard W.; Sauer, Peter E.; Drobniak, Agnieszka; Strąpoć, Dariusz; Mango, Frank D.

2018-06-01

Low temperature (60 and 100 °C) and long-term (6 months to 5 years) heating of pre-evacuated and sterilized shales and coals containing kerogen Types I (Mahogany Shale), II (Mowry Shale and New Albany Shale), and III (Springfield Coal and Wilcox Lignite) with low initial maturities (vitrinite reflectance Ro 0.39-0.62%) demonstrates that catalytically generated hydrocarbons may explain the occurrence of some non-biogenic natural gas accumulations where insufficient thermal maturity contradicts the conventional thermal cracking paradigm. Extrapolation of the observed rate of catalytic methanogenesis in the laboratory suggests that significant amounts of sedimentary organic carbon can be converted to relatively dry natural gas over tens of thousands of years in sedimentary basins at temperatures as low as 60 °C. Our laboratory experiments utilized source rock (shale and coal) chips sealed in gold and Pyrex® glass tubes in the presence of hydrogen-isotopically contrasting waters. Parallel heating experiments applied hydrostatic pressures from 0.1 to 300 MPa. Control experiments constrained the influence of pre-existing and residual methane in closed pores of rock chips that was unrelated to newly generated methane. This study's experimental methane yields at 60 and 100 °C are 5-11 orders of magnitude higher than the theoretically predicted yields from kinetic models of thermogenic methane generation, which strongly suggests a contribution of catalytic methanogenesis. Higher temperature, longer heating time, and lower hydrostatic pressure enhanced catalytic methanogenesis. No clear relationships were observed between kerogen type or total organic carbon content and methane yields via catalysis. Catalytic methanogenesis was strongest in Mowry Shale where methane yields at 60 °C amounted to ∼2.5 μmol per gram of organic carbon after one year of hydrous heating at ambient pressure. In stark contrast to the earlier findings of hydrogen isotopic exchange between

Methane production from marine, green macro-algae

Energy Technology Data Exchange (ETDEWEB)

Hansson, G.

1983-01-01

Fermentation studies have been carried out to produce methane from green algae native to Scandinavian water and suitable for large scale cultivation. Long term semi-continuous fermentations during mesophilic and thermophilic conditions were performed as well as batch fermentations in flasks and syringes. A mixed inoculum was prepared from sediments, rotting seaweed, sewage sludge and rumen contents. Methane production from the seaweed substrate, consisting of ground green algae without any nutrient additions, started immediately in this culture, mesophilicly as well as thermophilicly. Fermentations were carried out with retention times from 27 to 11 days and loading rates from 1.1 to 2.6 g volatile solids (VS added) per litre per day. In the mesophilic fermentation, gas yields were 250-350 ml CH/sub 4//g VS added and the VS-reduction was around 50-55% at all tested retention times and loading rates. The level of volatile fatty acids was very low in this system. In the thermophilic digestor, gas yields were somewhat lower although the VS-reduction was around 50% also in this systems. The VFA-levels were higher and the culture more sensitive to disturbances. Thus no advantages were found with the thermophilic fermentation. In mesophilic batch fermentations the gas production was rather rapid and almost completed after 12-15 days, in agreement with the continuous fermentations. The gas yields in batch experiments were high, 350-480 ml CH/sub 4//g VS added. (Refs. 20).

Effects of Co and Ni nanoparticles on biogas and methane production from anaerobic digestion of slurry

International Nuclear Information System (INIS)

Abdelsalam, E.; Samer, M.; Attia, Y.A.; Abdel-Hadi, M.A.; Hassan, H.E.; Badr, Y.

2017-01-01

Highlights: • The addition of trace metals in form of nanoparticles reduced the lag phase. • Nanoparticles reduced time to achieve the highest biogas and methane production. • Biogas and methane production were proportional to nanoparticles concentration. • Nanoparticles biostimulate the methanogenic bacteria and increase their activity. - Abstract: Nanoparticles (NPs) were hypothesized to enhance the anaerobic process and to accelerate the slurry digestion, which increases the biogas and methane production. The effects of NPs on biogas and methane production were investigated using a specially designed batch anaerobic system. For this purpose, a series of 2 L biodigesters were manufactured and implemented to study the effects of Cobalt (Co) and Nickel (Ni) nanoparticles with different concentrations on biogas and methane production. The best results of NPs additives were determined based on the statistical analysis (Least Significant Difference using M-Stat) of biogas and methane production, which were 1 mg/L Co NPs and 2 mg/L Ni NPs (p < 0.05). These NPs additives delivered the highest biogas and methane yields in comparison with their other concentrations (0.5, 1, and 2 mg/L), their salts (CoCl_2, and NiCl_2) and the control. Furthermore, the addition of 1 mg/L Co NPs and 2 mg/L Ni NPs significantly increased the biogas volume (p < 0.05) by 1.64 and 1.74 times the biogas volume produced by the control, respectively. Moreover, the aforementioned additives significantly increased the methane volume (p < 0.05) by 1.86 and 2.01 times the methane volume produced by the control, respectively. The highest specific biogas and methane production were attained with 2 mg/L Ni NPs (p < 0.05), and were 614.5 ml Biogas g"−"1 VS and 361.6 ml CH_4 g"−"1 VS, respectively compared with the control which yielded only 352.6 ml Biogas g"−"1 VS and 179.6 ml CH_4 g"−"1 VS.

Determination of as-discarded methane potential in residential and commercial municipal solid waste.

Science.gov (United States)

Chickering, Giles W; Krause, Max J; Townsend, Timothy G

2018-06-01

Methane generation potential, L 0 , is a primary parameter of the first-order decay (FOD) model used for prediction and regulation of landfill gas (LFG) generation in municipal solid waste (MSW) landfills. The current US EPA AP-42 default value for L 0 , which has been in place for almost 20 years, is 100 m 3 CH 4 /Mg MSW as-discarded. Recent research suggests the yield of landfilled waste could be less than 60 m 3 CH 4 /Mg MSW. This study aimed to measure the L 0 of present-day residential and commercial as-discarded MSW. In doing so, 39 waste collection vehicles were sorted for composition before samples of each biodegradable fraction were analyzed for methane generation potential. Methane yields were determined for over 450 samples of 14 different biodegradable MSW fractions, later to be combined with moisture content and volatile solids data to calculate L 0 values for each waste load. An average value of 80 m 3 CH 4 /Mg MSW was determined for all samples with 95% of values in the interval 74-86 m 3 CH 4 /Mg MSW as-discarded. While no statistically significant difference was observed, commercial MSW yields (mean 85, median 88 m 3 CH 4 /Mg MSW) showed a higher average L 0 than residential MSW (mean 75, median 71 m 3 CH 4 /Mg MSW). Many methane potential values for individual fractions described in previous work were found within the range of values determined by BMP in this study. Copyright © 2018 Elsevier Ltd. All rights reserved.

Azolla planting reduces methane emission and nitrogen fertilizer application in double rice cropping system in southern China

DEFF Research Database (Denmark)

Xu, Heshui; Zhu, Bo; Liu, Jingna

2017-01-01

Rice paddies are a major source of methane. How to reduce the methane emission in the paddy field without decreasing the yield has become a major concern of scientists, environmental groups, and agricultural policymakers worldwide. Azolla, used as a dual crop in rice cultivation, has multiple agr...

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

Science.gov (United States)

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

2013-01-01

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

Occurrence and origin of methane in groundwater in Alberta (Canada): Gas geochemical and isotopic approaches

International Nuclear Information System (INIS)

Humez, P.; Mayer, B.; Ing, J.; Nightingale, M.; Becker, V.; Kingston, A.; Akbilgic, O.; Taylor, S.

2016-01-01

To assess potential future impacts on shallow aquifers by leakage of natural gas from unconventional energy resource development it is essential to establish a reliable baseline. Occurrence of methane in shallow groundwater in Alberta between 2006 and 2014 was assessed and was ubiquitous in 186 sampled monitoring wells. Free and dissolved gas sampling and measurement approaches yielded comparable results with low methane concentrations in shallow groundwater, but in 28 samples from 21 wells methane exceeded 10 mg/L in dissolved gas and 300,000 ppmv in free gas. Methane concentrations in free and dissolved gas samples were found to increase with well depth and were especially elevated in groundwater obtained from aquifers containing coal seams and shale units. Carbon isotope ratios of methane averaged − 69.7 ± 11.1‰ (n = 63) in free gas and − 65.6 ± 8.9‰ (n = 26) in dissolved gas. δ"1"3C values were not found to vary with well depth or lithology indicating that methane in Alberta groundwater was derived from a similar source. The low δ"1"3C values in concert with average δ"2H_C_H_4 values of − 289 ± 44‰ (n = 45) suggest that most methane was of biogenic origin predominantly generated via CO_2 reduction. This interpretation is confirmed by dryness parameters typically > 500 due to only small amounts of ethane and a lack of propane in most samples. Comparison with mud gas profile carbon isotope data revealed that methane in the investigated shallow groundwater in Alberta is isotopically similar to hydrocarbon gases found in 100–250 meter depths in the WCSB and is currently not sourced from thermogenic hydrocarbon occurrences in deeper portions of the basin. The chemical and isotopic data for methane gas samples obtained from Alberta groundwater provide an excellent baseline against which potential future impact of deeper stray gases on shallow aquifers can be assessed. - Highlights: • Analysis of gas geochemical data from 186 monitoring wells in

Occurrence and origin of methane in groundwater in Alberta (Canada): Gas geochemical and isotopic approaches

Energy Technology Data Exchange (ETDEWEB)

Humez, P., E-mail: phumez@ucalgary.ca [Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4 (Canada); Mayer, B.; Ing, J.; Nightingale, M.; Becker, V.; Kingston, A. [Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4 (Canada); Akbilgic, O. [Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4 (Canada); UTHSC-ORNL Center for Biomedical Informatics, 910 Madison Avenue, Memphis, TN, 38104 (United States); Taylor, S. [Department of Geoscience, University of Calgary, 2500 University Drive NW, Calgary, Alberta T2N 1N4 (Canada)

2016-01-15

To assess potential future impacts on shallow aquifers by leakage of natural gas from unconventional energy resource development it is essential to establish a reliable baseline. Occurrence of methane in shallow groundwater in Alberta between 2006 and 2014 was assessed and was ubiquitous in 186 sampled monitoring wells. Free and dissolved gas sampling and measurement approaches yielded comparable results with low methane concentrations in shallow groundwater, but in 28 samples from 21 wells methane exceeded 10 mg/L in dissolved gas and 300,000 ppmv in free gas. Methane concentrations in free and dissolved gas samples were found to increase with well depth and were especially elevated in groundwater obtained from aquifers containing coal seams and shale units. Carbon isotope ratios of methane averaged − 69.7 ± 11.1‰ (n = 63) in free gas and − 65.6 ± 8.9‰ (n = 26) in dissolved gas. δ{sup 13}C values were not found to vary with well depth or lithology indicating that methane in Alberta groundwater was derived from a similar source. The low δ{sup 13}C values in concert with average δ{sup 2}H{sub CH4} values of − 289 ± 44‰ (n = 45) suggest that most methane was of biogenic origin predominantly generated via CO{sub 2} reduction. This interpretation is confirmed by dryness parameters typically > 500 due to only small amounts of ethane and a lack of propane in most samples. Comparison with mud gas profile carbon isotope data revealed that methane in the investigated shallow groundwater in Alberta is isotopically similar to hydrocarbon gases found in 100–250 meter depths in the WCSB and is currently not sourced from thermogenic hydrocarbon occurrences in deeper portions of the basin. The chemical and isotopic data for methane gas samples obtained from Alberta groundwater provide an excellent baseline against which potential future impact of deeper stray gases on shallow aquifers can be assessed. - Highlights: • Analysis of gas geochemical data from 186

Catalytic combustion for the elimination of methane, BTEX and other VOC : IV

International Nuclear Information System (INIS)

Hayes, R.E.; Wanke, S.E.

2008-01-01

Options for volatile organic compound combustion include homogeneous combustion (flaring) or catalytic combustion involving a flameless combustion process that uses a solid catalyst to promote the combustion reaction. This presentation discussed relative reactivity testing for volatile organic compounds (VOCs) over commercial catalysts. Several commercial pad catalysts were tested, as well as other powders. The relative reactivity of methane as well as benzene, toluene, ethylbenzene, and xylene (BTEX) were investigated. The purpose of the project was to evaluate combustion of concentrated methane streams that contained BTEX compounds; evaluate catalytic combustion using a counter diffusive radiant heater; develop mathematical models for the reactor to enhance design and understanding; improve the catalyst for BTEX combustion; and target application-dehydrator units. Topics that were addressed in the presentation included methane and benzene conversion; catalytic radiant heaters; small industrial and commercial units; measured temperature distribution; fuel slippage, methane conversion; the effect of water and hydrocarbons; the effect of water-liquid injection; and water addition as vapour. Several observations were offered, including that high percentages of injected liquid water can reduce reactor operating temperature; combustion of BTEX remained highly efficient, however liquid injection could also cause temperature reductions and ultimately the reactor would extinguish; and pre-heating the feed can eliminate the temperature drop and pad wetness problem. It was concluded that BTEX compounds are reactive, and the technology appears promising. 19 figs

Catalytic combustion for the elimination of methane, BTEX and other VOC : IV

Energy Technology Data Exchange (ETDEWEB)

Hayes, R.E.; Wanke, S.E. [Alberta Univ., Edmonton, AB (Canada). Dept. of Chemical and Materials Engineering

2008-07-01

Options for volatile organic compound combustion include homogeneous combustion (flaring) or catalytic combustion involving a flameless combustion process that uses a solid catalyst to promote the combustion reaction. This presentation discussed relative reactivity testing for volatile organic compounds (VOCs) over commercial catalysts. Several commercial pad catalysts were tested, as well as other powders. The relative reactivity of methane as well as benzene, toluene, ethylbenzene, and xylene (BTEX) were investigated. The purpose of the project was to evaluate combustion of concentrated methane streams that contained BTEX compounds; evaluate catalytic combustion using a counter diffusive radiant heater; develop mathematical models for the reactor to enhance design and understanding; improve the catalyst for BTEX combustion; and target application-dehydrator units. Topics that were addressed in the presentation included methane and benzene conversion; catalytic radiant heaters; small industrial and commercial units; measured temperature distribution; fuel slippage, methane conversion; the effect of water and hydrocarbons; the effect of water-liquid injection; and water addition as vapour. Several observations were offered, including that high percentages of injected liquid water can reduce reactor operating temperature; combustion of BTEX remained highly efficient, however liquid injection could also cause temperature reductions and ultimately the reactor would extinguish; and pre-heating the feed can eliminate the temperature drop and pad wetness problem. It was concluded that BTEX compounds are reactive, and the technology appears promising. 19 figs.

Effects of co-digestion of cucumber residues to corn stover and pig manure ratio on methane production in solid state anaerobic digestion.

Science.gov (United States)

Wang, Yaya; Li, Guoxue; Chi, Menghao; Sun, Yanbo; Zhang, Jiaxing; Jiang, Shixu; Cui, Zongjun

2018-02-01

This study investigated the performance of co-digesting cucumber residues, corn stover, and pig manure at different ratios. Microbial community structure was analyzed to elucidate functional microorganism contributing to methane production during co-digestion. Results show that mixing cucumber residues with pig manure and corn stover could significantly improved methane yields 1.27-3.46 times higher than mono-feedstock. The methane yields decreased with the cucumber residues increasing when the pig manure ratio was fixed at 4 and 3, and was opposite at ratio 5. The optimal mixture ratio was T2 with the highest methane yield (305.4 mL/g VS) and co-digestion performance index (1.97). The main microbiological community in T2 was bacteria of Firmicutes (44.6%), Bacteroidetes (32.5%), Synergistetes (3.8%) and archaea of Methanosaeta (37.1%), Methanospirillum (18.2%). The mixture ratios changed the microbial community structures. The adding proportion of cucumber residues changed the community composition of the archaea, especially the proportion of Methanosaeta. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ultrasonic sludge disintegration for enhanced methane production in anaerobic digestion: effects of sludge hydrolysis efficiency and hydraulic retention time.

Science.gov (United States)

Kim, Dong-Jin; Lee, Jonghak

2012-01-01

Hydrolysis of waste activated sludge (WAS) has been regarded as the rate limiting step of anaerobic sludge digestion. Therefore, in this study, the effect of ultrasound and hydraulic residence time during sludge hydrolysis was investigated with the goal of enhancing methane production from anaerobic digestion (AD). WAS was ultrasonically disintegrated for hydrolysis, and it was semi-continuously fed to an anaerobic digesters at various hydraulic retention times (HRTs). The results of these experiments showed that the solids and chemical oxygen demand (COD) removal efficiencies when using ultrasonically disintegrated sludge were higher during AD than the control sludge. The longer the HRT, the higher the removal efficiencies of solids and COD, while methane production increased with lower HRT. Sludge with 30% hydrolysis produced 7 × more methane production than the control sludge. The highest methane yields were 0.350 m(3)/kg volatile solids (VS)(add) and 0.301 m(3)/kg COD(con) for 16 and 30% hydrolyzed sludge, respectively. In addition, we found that excess ultrasound irradiation may inhibit AD since the 50% hydrolyzed sludge produced lower methane yields than 16 and 30% hydrolyzed sludge.

Methane production and methane consumption: a review of processes underlying wetland methane fluxes.

NARCIS (Netherlands)

Segers, R.

1998-01-01

Potential rates of both methane production and methane consumption vary over three orders of magnitude and their distribution is skew. These rates are weakly correlated with ecosystem type, incubation temperature, in situ aeration, latitude, depth and distance to oxic/anoxic interface. Anaerobic

The social cost of methane: theory and applications.

Science.gov (United States)

Shindell, D T; Fuglestvedt, J S; Collins, W J

2017-08-24

Methane emissions contribute to global warming, damage public health and reduce the yield of agricultural and forest ecosystems. Quantifying these damages to the planetary commons by calculating the social cost of methane (SCM) facilitates more comprehensive cost-benefit analyses of methane emissions control measures and is the first step to potentially incorporating them into the marketplace. Use of a broad measure of social welfare is also an attractive alternative or supplement to emission metrics focused on a temperature target in a given year as it incentivizes action to provide benefits over a broader range of impacts and timescales. Calculating the SCM using consistent temporal treatment of physical and economic processes and incorporating climate- and air quality-related impacts, we find large SCM values, e.g. ∼$2400 per ton and ∼$3600 per ton with 5% and 3% discount rates respectively. These values are ∼100 and 50 times greater than corresponding social costs for carbon dioxide. Our results suggest that ∼110 of 140 Mt of identified methane abatement via scaling up existing technology and policy options provide societal benefits that outweigh implementation costs. Within the energy sector, renewables compare far better against use of natural gas in electricity generation when incorporating these social costs for methane. In the agricultural sector, changes in livestock management practices, promoting healthy diets including reduced beef and dairy consumption, and reductions in food waste have been promoted as ways to mitigate emissions, and these are shown here to indeed have the potential to provide large societal benefits (∼$50-150 billion per year). Examining recent trends in methane and carbon dioxide, we find that increases in methane emissions may have offset much of the societal benefits from a slowdown in the growth rate of carbon dioxide emissions. The results indicate that efforts to reduce methane emissions via policies spanning a wide

Semi-continuous anaerobic digestion of different silage crops: VFAs formation, methane yield from fiber and non-fiber components and digestate composition.

Science.gov (United States)

Pokój, T; Bułkowska, K; Gusiatin, Z M; Klimiuk, E; Jankowski, K J

2015-08-01

This study presents the results of long-term semi-continuous experiments on anaerobic digestion at an HRT of 45d with ten silages: 2 annual and 4 perennial crops, and 4 mixtures of annual with perennial crops. The composition of substrates and digestates was determined with Van Soest's fractionation method. Removal of non-fiber materials ranged from 49.4% (Miscanthus sacchariflorus) to 89.3% (Zea mays alone and mixed with M. sacchariflorus), that of fiber materials like lignin ranged from 0.005% (Z. mays alone and mixed with grasses at VS ratio of 90:10%) to 46.5% (Sida hermaphrodita). The lowest stability of anaerobic digestion, as confirmed by normalized data concentrations of volatile fatty acids, was reported for both miscanthuses and sugar sorghum. The methane yield coefficients for non-fiber and fiber materials were 0.3666 and 0.2556L/g, respectively. All digestate residues had high fertilizing value, especially those from mixtures of crops. Copyright © 2015 Elsevier Ltd. All rights reserved.

Kinetic modelling of methane production during bio-electrolysis from anaerobic co-digestion of sewage sludge and food waste.

Science.gov (United States)

Prajapati, Kalp Bhusan; Singh, Rajesh

2018-05-10

In present study batch tests were performed to investigate the enhancement in methane production under bio-electrolysis anaerobic co-digestion of sewage sludge and food waste. The bio-electrolysis reactor system (B-EL) yield more methane 148.5 ml/g COD in comparison to reactor system without bio-electrolysis (B-CONT) 125.1 ml/g COD. Whereas bio-electrolysis reactor system (C-EL) Iron Scraps amended yield lesser methane (51.2 ml/g COD) in comparison to control bio-electrolysis reactor system without Iron scraps (C-CONT - 114.4 ml/g COD). Richard and Exponential model were best fitted for cumulative methane production and biogas production rates respectively as revealed modelling study. The best model fit for the different reactors was compared by Akaike's Information Criterion (AIC) and Bayesian Information Criterion (BIC). The bioelectrolysis process seems to be an emerging technology with lesser the loss in cellulase specific activity with increasing temperature from 50 to 80 °C. Copyright © 2018 Elsevier Ltd. All rights reserved.

Prediction of the methane conversion factor (Ym) for dairy cows on the basis of national farm data

DEFF Research Database (Denmark)

Hellwing, Anne Louise Frydendahl; Weisbjerg, Martin Riis; Brask, Maike

2016-01-01

Methane constitutes a significant loss of feed gross energy in ruminants, and there is an ongoing struggle for identifying feed and animal characteristics feasible for documentation of National Greenhouse Gas Inventories. The aim of the current study was to develop a model that predicts the methane...... and feed composition as variables, and one using yield of energy corrected milk and feed composition as variables. The methane conversion factor was significantly reduced with increased content of starch and fat in the ration, whereas neutral detergent fibre content surprisingly did not have a significant...

Methanation of carbon oxides. History, status quo and future perspectives

Energy Technology Data Exchange (ETDEWEB)

Kaltner, W.; Rakoczy, R.A. [Clariant SE, Muenchen (Germany)

2012-07-01

With increasing demand in fossil sources and especially crude oil based energy carrier, proven reserves will be diminishing. Besides alternative and sustainable sources the conversion of coal into fuels which can be distributed within the existing infrastructure becomes extremely important in areas of fast growing energy demand. Driver for these technologies is mostly the lack of crude oil and availability of coal like in China or South Africa. The most common way to convert coal into chemicals and fuels is the gasification to yield a gas mixture known as synthesis gas. Synthesis gas can be converted in highly pure methane used as 'substitute natural gas' (SNG) in gas grids of major cities to produce heat at home and industry. All available SNG technologies are characterized by the difficulty to control the extreme heat release of the methanation reaction. This presentation will give an overview on available gasification and methanation technologies from recent point of view. A lot of processes are already described in literature and there are pilot and real plants for methanation and especially SNG built. Moreover, a new process to produce methane from synthesis gas without the need of recycle streams and high temperatures will be introduced. This novel process developed by Foster Wheeler - using catalysts from Clariant - is called 'VESTA Process' in accordance with the Roman goddess of hearth and fire. (orig.)

Efficient production of ethanol from waste paper and the biochemical methane potential of stillage eluted from ethanol fermentation.

Science.gov (United States)

Nishimura, Hiroto; Tan, Li; Sun, Zhao-Yong; Tang, Yue-Qin; Kida, Kenji; Morimura, Shigeru

2016-02-01

Waste paper can serve as a feedstock for ethanol production due to being rich in cellulose and not requiring energy-intensive thermophysical pretreatment. In this study, an efficient process was developed to convert waste paper to ethanol. To accelerate enzymatic saccharification, pH of waste paper slurry was adjusted to 4.5-5.0 with H2SO4. Presaccharification and simultaneous saccharification and fermentation (PSSF) with enzyme loading of 40 FPU/g waste paper achieved an ethanol yield of 91.8% and productivity of 0.53g/(Lh) with an ethanol concentration of 32g/L. Fed-batch PSSF was used to decrease enzyme loading to 13 FPU/g waste paper by feeding two separate batches of waste paper slurry. Feeding with 20% w/w waste paper slurry increased ethanol concentration to 41.8g/L while ethanol yield decreased to 83.8%. To improve the ethanol yield, presaccharification was done prior to feeding and resulted in a higher ethanol concentration of 45.3g/L, a yield of 90.8%, and productivity of 0.54g/(Lh). Ethanol fermentation recovered 33.2% of the energy in waste paper as ethanol. The biochemical methane potential of the stillage eluted from ethanol fermentation was 270.5mL/g VTS and 73.0% of the energy in the stillage was recovered as methane. Integrating ethanol fermentation with methane fermentation, recovered a total of 80.4% of the energy in waste paper as ethanol and methane. Copyright © 2015 Elsevier Ltd. All rights reserved.

Influence of solid-liquid separation strategy on biogas yield from a stratified swine production system.

Science.gov (United States)

Cestonaro do Amaral, André; Kunz, Airton; Radis Steinmetz, Ricardo Luis; Scussiato, Lucas Antunes; Tápparo, Deisi Cristina; Gaspareto, Taís Carla

2016-03-01

As the fourth largest swine producer and exporter, Brazil has increased its participation in the global swine production market. Generally, these units concentrate a large number of animals and generate effluents that must be correctly managed to prevent environmental impacts, being anaerobic digestion is an interesting alternative for treating these effluents. The low-volatile solid concentration in the manure suggests the need for solid-liquid separation as a tool to improve the biogas generation capacity. This study aimed to determine the influence of simplified and inexpensive solid-liquid separation strategies (screening and settling) and the different manures produced during each swine production phase (gestating and farrowing sow houses, nursery houses and finishing houses) on biogas and methane yield. We collected samples in two gestating sow houses (GSH-a and GSH-b), two farrowing sow houses (FSH-a and FSH-b), a nursery house (NH) and a finishing house (FH). Biochemical methane potential (BMP) tests were performed according to international standard procedures. The settled sludge fraction comprised 20-30% of the raw manure volume, which comprises 40-60% of the total methane yield. The methane potential of the settled sludge fraction was approximately two times higher than the methane potential of the supernatant fraction. The biogas yield differed among the raw manures from different swine production phases (GSH-a 326.4 and GSH-b 577.1; FSH-a 860.1 and FSH-b 479.2; NH -970.2; FH 474.5 NmLbiogas.gVS(-1)). The differences were relative to the production phase (feed type and feeding techniques) and the management of the effluent inside the facilities (water management). Brazilian swine production has increased his participation in the global market, been the fourth producer and the fourth exporter. The segregation of swine production in multiple sites has increased its importance, due to the possibilities to have more specialized units. Generally, these units

Production of carbon molecular sieves from palm shell through carbon deposition from methane

Directory of Open Access Journals (Sweden)

Mohammadi Maedeh

2011-01-01

Full Text Available The possibility of production of carbon molecular sieve (CMS from palm shell as a waste lignocellulosic biomass was investigated. CMS samples were prepared through heat treatment processes including carbonization, physiochemical activation and chemical vapor deposition (CVD from methane. Methane was pyrolyzed to deposit fine carbon on the pore mouth of palm shell-based activated carbon to yield CMS. All the deposition experiments were performed at 800 ºC, while the methane flow rate (100, 200, 300 mL min-1 CH4 diluted in 500 mL min-1 N2 and deposition time (30 to 60 min were the investigated parameters. The textural characteristics of the CMSs were assessed by N2 adsorption. The largest BET surface area (752 m2 g-1, micropore surface area (902.2 m2 g-1 and micropore volume (0.3466 cm3 g-1 was obtained at the CH4 flow rate of 200 mL min-1 and deposition time of 30 min. However, prolonging the deposition time to 45 min yielded in a micropouros CMS with a narrow pore size distribution.

Catalytic conversion of methane: Carbon dioxide reforming and oxidative coupling

KAUST Repository

Takanabe, Kazuhiro

2012-01-01

Natural gas conversion remains one of the essential technologies for current energy needs. This review focuses on the mechanistic aspects of the development of efficient and durable catalysts for two reactions, carbon dioxide reforming and the oxidative coupling of methane. These two reactions have tremendous technological significance for practical application in industry. An understanding of the fundamental aspects and reaction mechanisms of the catalytic reactions reviewed in this study would support the design of industrial catalysts. CO 2 reforming of methane utilizes CO 2, which is often stored in large quantities, to convert as a reactant. Strategies to eliminate carbon deposition, which is the major problem associated with this reaction, are discussed. The oxidative coupling of methane directly produces ethylene in one reactor through a slightly exothermic reaction, potentially minimizing the capital cost of the natural gas conversion process. The focus of discussion in this review will be on the attainable yield of C 2 products by rigorous kinetic analyses.

Flux scaling: Ultimate regime

Indian Academy of Sciences (India)

First page Back Continue Last page Overview Graphics. Flux scaling: Ultimate regime. With the Nusselt number and the mixing length scales, we get the Nusselt number and Reynolds number (w'd/ν) scalings: and or. and. scaling expected to occur at extremely high Ra Rayleigh-Benard convection. Get the ultimate regime ...

Atmospheric methane removal by methane-oxidizing bacteria immobilized on porous building materials.

Science.gov (United States)

Ganendra, Giovanni; De Muynck, Willem; Ho, Adrian; Hoefman, Sven; De Vos, Paul; Boeckx, Pascal; Boon, Nico

2014-04-01

Biological treatment using methane-oxidizing bacteria (MOB) immobilized on six porous carrier materials have been used to mitigate methane emission. Experiments were performed with different MOB inoculated in building materials at high (~20 % (v/v)) and low (~100 ppmv) methane mixing ratios. Methylocystis parvus in autoclaved aerated concrete (AAC) exhibited the highest methane removal rate at high (28.5 ± 3.8 μg CH₄ g⁻¹ building material h⁻¹) and low (1.7 ± 0.4 μg CH₄ g⁻¹ building material h⁻¹) methane mixing ratio. Due to the higher volume of pores with diameter >5 μm compared to other materials tested, AAC was able to adsorb more bacteria which might explain for the higher methane removal observed. The total methane and carbon dioxide-carbon in the headspace was decreased for 65.2 ± 10.9 % when M. parvus in Ytong was incubated for 100 h. This study showed that immobilized MOB on building materials could be used to remove methane from the air and also act as carbon sink.

Meta-analysis of relationships between enteric methane yield and milk fatty acid profile in dairy cattle

NARCIS (Netherlands)

Lingen, van H.J.; Crompton, L.A.; Hendriks, W.H.; Reynolds, C.K.; Dijkstra, J.

2014-01-01

Various studies have indicated a relationship between enteric methane (CH4) production and milk fatty acid (FA) profiles of dairy cattle. However, the number of studies investigating such a relationship is limited and the direct relationships reported are mainly obtained by variation in CH4

Rain increases methane production and methane oxidation in a boreal thermokarst bog

Science.gov (United States)

Neumann, R. B.; Moorberg, C.; Turner, J.; Wong, A.; Waldrop, M. P.; Euskirchen, E. S.; Edgar, C.; Turetsky, M. R.

2017-12-01

Bottom-up biogeochemical models of wetland methane emissions simulate the response of methane production, oxidation and transport to wetland conditions and environmental forcings. One reason for mismatches between bottom-up and top-down estimates of emissions is incomplete knowledge of factors and processes that control microbial rates and methane transport. To advance mechanistic understanding of wetland methane emissions, we conducted a multi-year field investigation and plant manipulation experiment in a thermokarst bog located near Fairbanks, Alaska. The edge of the bog is experiencing active permafrost thaw, while the center of the bog thawed 50 to 100 years ago. Our study, which captured both an average year and two of the wettest years on record, revealed how rain interacts with vascular vegetation and recently thawed permafrost to affect methane emissions. In the floating bog, rain water warmed and oxygenated the subsurface, but did not alter soil saturation. The warmer peat temperatures increased both microbial methane production and plant productivity at the edge of the bog near the actively thawing margin, but minimally altered microbial and plant activity in the center of the bog. These responses indicate processes at the edge of the bog were temperature limited while those in the center were not. The compounding effect of increased microbial activity and plant productivity at the edge of the bog doubled methane emissions from treatments with vascular vegetation during rainy years. In contrast, methane emissions from vegetated treatments in the center of the bog did not change with rain. The oxygenating influence of rain facilitated greater methane oxidation in treatments without vascular vegetation, which offset warming-induced increases in methane production at the edge of the bog and decreased methane emissions in the center of the bog. These results elucidate the complex and spatially variable response of methane production and oxidation in

Modelling methane emission mitigation by anaerobic digestion: effect of storage conditions and co-digestion.

Science.gov (United States)

Moset, Veronica; Wahid, R; Ward, A; Møller, H B

2018-03-13

In this work the methane conversion factor (MCF) of untreated and anaerobically digested cattle manure (CM) as a function of storage temperature, time and co-digestion was measured in an in vitro experiment and modelled based on IPCC (2006) methodology (Tier 2). For this, one sample of untreated CM, one sample of mono-digested CM and three samples of CM co-digested with grass were incubated at seven different temperatures (from 5°C to 50°C) over 346 days. The main results showed that ultimate methane yield (B 0 ) of CM is higher than the B 0 reported by the IPCC (2006). Two temperature ranges should be considered for MCF evolution, below 15°C very low MCF was measured in this work for untreated CM, mono and co-digested samples. At higher temperatures, MCF obtained in this work and that provided by the IPCC could be comparable depending on storage time. Anaerobic mono-digestion decreased MCF compared to untreated CM at all temperatures and times, except in the temperature range between 20°C and 25°C if storage time is low, due to a lag phase observed in CM. This lag phase would probably not happen in real storage conditions depending on the proportion of old manure remaining in the storage tank. Co-digestion with grass-decreased MCF compared to mono-digestion, but increased CH 4 production in terms of fresh matter due to the higher B 0 of the mixture. Storage time, temperature and co-digestion should be considered in the quantification of CH 4 emission from digested material.

Performance of sorghum cultivars for biomass quality and biomethane yield grown in semi-arid area of Pakistan.

Science.gov (United States)

Hassan, Muhammad Umair; Chattha, Muhammad Umer; Mahmood, Athar; Sahi, Shahbaz Talib

2018-05-01

Biomass is a promising renewable energy source and its significance is escalating in the context of climate change and depletion of fossil foils. This study was conducted for two consecutive years 2016 and 2017, using five sorghum cultivars, i.e., JS-263, Jawar-2011, Hagari, JS-2002, and YS-2016, in order to determine the best cultivars in terms of dry matter yield, chemical composition, and biomethane yield grown under semi-arid conditions in Pakistan. The results revealed that sorghum cultivars responded differently in terms of growth, biomass yield, chemical composition, and methane yield. Cultivars Jawar-2011 produced maximum leaf area index, leaf area duration, crop growth rate, plant height, and leaves per plant, however, they were comparable with Sorghum-2016, whereas cultivar JS-2002 performed poorly among the tested cultivars. Similarly, cultivar Jawar-2011 produced maximum dry matter yield (16.37 t ha -1 ) similar to that of YS-2016, further cultivar JS-2002 performed poorly and gave lower dry matter yield (12.87 t ha -1 ). The maximum protein concentration (10.95), neutral detergent fibers (61.20), and lignin contents (5.55) found in Jawar-2011 were comparable with those in YS-2016, while the lowest neutral detergent fiber and lignin contents were found in JS-2002. Although JS-2002 produced the highest specific methane yield per kilogram of volatile solids, it was overcompensated by Jawar-2011 owing to higher dry matter yield per hectare. These results suggested that cultivar Jawar-2011 can be grown successfully in semi-arid conditions of Pakistan in order to get good biomass yield along with higher methane yield.

Ensiling of fish industry waste for biogas production: a lab scale evaluation of biochemical methane potential (BMP) and kinetics.

Science.gov (United States)

Kafle, Gopi Krishna; Kim, Sang Hun; Sung, Kyung Ill

2013-01-01

Fish waste (FW) obtained from a fish processor was ensiled for biogas production. The FW silages were prepared by mixing FW with bread waste (BW) and brewery grain waste (BGW), and the quality of the prepared silages were evaluated. The biogas potentials of BW, BGW, three different types of FW, and FW silages were measured. A first-order kinetic model and the modified Gompertz model were also used to predict methane yield. The biogas and methane yield for FW silages after 96 days was calculated to be 671-763 mL/g VS and 441-482 mL/g VS, respectively. There were smaller differences between measured and predicted methane yield for FW silages when using a modified Gompertz model (1.1-4.3%) than when using a first-order kinetic model (22.5-32.4%). The critical HRTs and technical digestion times (T(80-90)) for the FW silages were calculated to be 21.0-23.8 days and 40.5-52.8 days, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effects of ensiling treatments on lactic acid production and supplementary methane formation of maize and amaranth--an advanced green biorefining approach.

Science.gov (United States)

Haag, Nicola Leonard; Nägele, Hans-Joachim; Fritz, Thomas; Oechsner, Hans

2015-02-01

A green biorefinery enables the material and energetic use of biomass via lactic acid and methane production. Different ensiling techniques were applied to maize and amaranth with the aim to increase the amount of lactic acid in the silage. In addition the methane formation potential of the ensiled samples and the remaining solid residues after separating the organic juice were assessed. Treating maize with homofermentative lactic acid bacteria in combination with carbonated lime increased the amount of lactic acid about 91.9%. For amaranth no additional lactic acid production was obtained by treating the raw material. Specific methane yields for the solid residues of amaranth were significantly lower in comparison to the corresponding silages. The most promising treatment resulted in a production of 127.9±4.1 g kg(-1) DM lactic acid and a specific methane yield for the solid residue of 349.5±6.6 lN kg(-1) ODM. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ionization of liquid argon by x-rays: effect of density on electron thermalization and free ion yields

International Nuclear Information System (INIS)

Huang, S.S.-S.; Gee, N.; Freeman, G.R.

1991-01-01

Free ion yields were measured in liquid argon as a function of electric field strength at densities 736-1343 kg/m 3 (temperatures 149-95 K). The field dependence of the yields was parametrized using the extended Onsager and box models. Over the present density range the total ion yield was constant within 1% and was taken as 4.4, the average of earlier values at 87-91 K. The absence of internal vibrational modes in argon makes its electron thermalizing ability smaller than that of methane. The electron thermalization distance b GP in liquid argon is 3-5 times longer than that in liquid methane at a given d/d c (d c = critical fluid density). (author)

Optimization of biohydrogen and methane recovery within a cassava ethanol wastewater/waste integrated management system

DEFF Research Database (Denmark)

Wang, Wen; Xie, Li; Luo, Gang

2012-01-01

Thermophilic co-fermentation of cassava stillage (CS) and cassava excess sludge (CES) were investigated for hydrogen and methane production. The highest hydrogen yield (37.1 ml/g-total-VS added) was obtained at VSCS/VSCES of 7:1, 17% higher than that with CS digestion alone. The CES recycle......, and the acetobacteria percentage increased to 12.4% at VSCS/VSCES of 6:2. Relatively high efficient and stable hydrogen production was observed at VSCS/VSCES of 5:3 without pH adjusted and any pretreatment. The highest total energy yield, the highest COD and VS degradation were obtained at VSCS/VSCES of 7:1. GFC...... analysis indicated that the hydrolysis behavior was significantly improved by CES recycle at both hydrogen and methane production phase....

Improved [13N]ammonia yield from the proton irradiation of water using methane gas

International Nuclear Information System (INIS)

Krasikova, R.N.; Fedorova, O.S.; Korsakov, M.V.; Landmeier Bennington, B.; Berridge, M.S.

1999-01-01

Production of N-13 ammonia directly in the cyclotron target has previously been accomplished by use of hydrogen pressurization or by addition of organic compounds, chiefly ethanol. All methods enjoy limited success and then either fail to produce ammonia at high beam dose, or require very high pressures to maintain ammonia production. We report that low-pressure methane gas in the target results in production of radiochemically pure ammonia throughout the feasible range of target irradiation conditions

Biogas generation in landfills. Equilibria, rates and yields

Energy Technology Data Exchange (ETDEWEB)

Aakesson, M

1997-05-01

Landfilling in `cells` has become more common in recent years. Different waste streams are guided to different cells, among which the biocell is a landfill designed for biogas production. In this thesis, the dependence of biogas generation on waste composition was investigated. Six 8,000 m{sup 3} test cells, with contents ranging from mainly commercial waste to pure domestic waste and equipped with gas extraction systems and bottom plastic liners, were monitored for seven years. Great emphasis was given to the characterization of conversion processes and governing mechanism in the topics of bio-energetics, kinetics and capacities. A thermodynamic model, in which the oxidations of volatile fatty acids (VFA) (2methane production rates and internal conditions observed during a two year period, demonstrated that high biogas rates corresponded with low VFA levels. To explain the discrepancies between theoretical methane potentials and quantified yields (in this study found to be 150-200 and 40-70 Nm{sup 3}/dry tonne, respectively), the possible nutritional limitation was investigated. Pools and emissions of chemical oxygen demand, N, P and K were quantified. Biomass pools were estimated from methane yields, growth yield coefficients, and bacterial mineral contents. However, results from commercial waste test cells showed that the assimilation of P exceeded the refuse content, which suggests the turnover of microbial biomass and questions the notion of nutritional limitation. In sum, the results showed that the advantages of a reduced content of readily biodegradable material, achieved by guidance or pretreatment, encompass several aspects of the performance. 84 refs, 6 figs, 1 tab

Anaerobic co-digestion of perennials: Methane potential and digestate nitrogen fertilizer value

DEFF Research Database (Denmark)

Muller-Stover, Dorette Sophie; Sun, Guotao; Kroff, Pablo

2016-01-01

Co-digestion of crop biomass improves the traditional manure-based biogas yield due to an increased content of easily degradable carbon compounds. In this study, the methane potential of three perennials (grass, legumes, and grass+legume) was determined using various amounts together with animal ...

Effect of thermal, chemical and thermo-chemical pre-treatments to enhance methane production

Energy Technology Data Exchange (ETDEWEB)

Rafique, Rashad; Nizami, Abdul-Sattar; Murphy, Jerry D.; Kiely, Gerard [Department of Civil and Environmental Engineering, University College Cork (Ireland); Poulsen, Tjalfe Gorm [Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University (Denmark); Asam, Zaki-ul-Zaman [Department of Civil Engineering, National University of Ireland Galway (Ireland)

2010-12-15

The rise in oil price triggered the exploration and enhancement of various renewable energy sources. Producing biogas from organic waste is not only providing a clean sustainable indigenous fuel to the number of on-farm digesters in Europe, but also reducing the ecological and environmental deterioration. The lignocellulosic substrates are not completely biodegraded in anaerobic digesters operating at commercial scale due to their complex physical and chemical structure, which result in meager energy recovery in terms of methane yield. The focus of this study is to investigate the effect of pre-treatments: thermal, thermo-chemical and chemical pre-treatments on the biogas and methane potential of dewatered pig manure. A laboratory scale batch digester is used for these pre-treatments at different temperature range (25 C-150 C). Results showed that thermo-chemical pretreatment has high effect on biogas and methane potential in the temperature range (25-100 C). Maximum enhancement is observed at 70 C with increase of 78% biogas and 60% methane production. Thermal pretreatment also showed enhancement in the temperature range (50-10 C), with maximum enhancement at 100 C having 28% biogas and 25% methane increase. (author)

Doses from radioactive methane

International Nuclear Information System (INIS)

Phipps, A.W.; Kendall, G.M.; Fell, T.P.; Harrison, J.D.

1990-01-01

A possible radiation hazard arises from exposure to methane labelled with either a 3 H or a 14 C nuclide. This radioactive methane could be released from a variety of sources, e.g. land burial sites containing radioactive waste. Standard assumptions adopted for vapours would not apply to an inert alkane like methane. This paper discusses mechanisms by which radioactive methane would irradiate tissues and provides estimates of doses. Data on skin thickness and metabolism of methane are discussed with reference to these mechanisms. It is found that doses are dominated by dose from the small fraction of methane which is inhaled and metabolised. This component of dose has been calculated under rather conservative assumptions. (author)

Hydrogen and methane production from condensed molasses fermentation soluble by a two-stage anaerobic process

Energy Technology Data Exchange (ETDEWEB)

Lin, Chiu-Yue; Liang, You-Chyuan; Lay, Chyi-How [Feng Chia Univ., Taichung, Taiwan (China). Dept. of Environmental Engineering and Science; Chen, Chin-Chao [Chungchou Institute of Technology, Taiwan (China). Environmental Resources Lab.; Chang, Feng-Yuan [Feng Chia Univ., Taichung, Taiwan (China). Research Center for Energy and Resources

2010-07-01

The treatment of condensed molasses fermentation soluble (CMS) is a troublesome problem for glutamate manufacturing factory. However, CMS contains high carbohydrate and nutrient contents and is an attractive and commercially potential feedstock for bioenergy production. The aim of this paper is to produce hydrogen and methane by two-stage anaerobic fermentation process. The fermentative hydrogen production from CMS was conducted in a continuously-stirred tank bioreactor (working volume 4 L) which was operated at a hydraulic retention time (HRT) of 8 h, organic loading rate (OLR) of 120 kg COD/m{sup 3}-d, temperature of 35 C, pH 5.5 and sewage sludge as seed. The anaerobic methane production was conducted in an up-flow bioreactor (working volume 11 L) which was operated at a HRT of 24 -60 hrs, OLR of 4.0-10 kg COD/m{sup 3}-d, temperature of 35 C, pH 7.0 with using anaerobic granule sludge from fructose manufacturing factory as the seed and the effluent from hydrogen production process as the substrate. These two reactors have been operated successfully for more than 400 days. The steady-state hydrogen content, hydrogen production rate and hydrogen production yield in the hydrogen fermentation system were 37%, 169 mmol-H{sub 2}/L-d and 93 mmol-H{sub 2}/g carbohydrate{sub removed}, respectively. In the methane fermentation system, the peak methane content and methane production rate were 66.5 and 86.8 mmol-CH{sub 4}/L-d with methane production yield of 189.3 mmol-CH{sub 4}/g COD{sub removed} at an OLR 10 kg/m{sup 3}-d. The energy production rate was used to elucidate the energy efficiency for this two-stage process. The total energy production rate of 133.3 kJ/L/d was obtained with 5.5 kJ/L/d from hydrogen fermentation and 127.8 kJ/L/d from methane fermentation. (orig.)

Methane potential of sterilized solid slaughterhouse wastes.

Science.gov (United States)

Pitk, Peep; Kaparaju, Prasad; Vilu, Raivo

2012-07-01

The aim of the current study was to determine chemical composition and methane potential of Category 2 and 3 solid slaughterhouse wastes rendering products (SSHWRP) viz. melt, decanter sludge, meat and bone meal (MBM), technical fat and flotation sludge from wastewater treatment. Chemical analyses showed that SSHWRP were high in protein and lipids with total solids (TS) content of 96-99%. Methane yields of the SSHWRP were between 390 and 978 m(3) CH(4)/t volatile solids (VS)(added). Based on batch experiments, anaerobic digestion of SSHWRP from the dry rendering process could recover 4.6 times more primary energy than the energy required for the rendering process. Estonia has technological capacity to sterilize all the produced Category 2 and 3 solid slaughterhouse wastes (SSHW) and if separated from Category 1 animal by-products (ABP), it could be further utilized as energy rich input material for anaerobic digestion. Copyright © 2012 Elsevier Ltd. All rights reserved.

Production of methane from kallar grass grown on saline sodic lands: metabolism of carbohydrates, methylated amines and methane precursors during digestion of kallar grass

International Nuclear Information System (INIS)

Tabassum, R.; Rajoka, M.I.; Malik, K.A.

1991-01-01

Mesophilic anaerobic digestion of kallar grass on saline sodic land was carried out in batch culture at laboratory scale with enriched culture from biogas plant. Analysis were made to determine biogas volume, gas composition and distribution of volatile fatty acids. The fermentation of kallar grass treated with 2% NaOH showed an increase in digestibility from 20-50% and the conversion efficiency approached 80-95% of theoretical yield which was fold higher than the one obtained from untreated substrates. The contents of methane in bio gas was markedly low during the first day of digestion but increased from 75 to 91% at the end of 20 days retention time. Low pH values (6.2) showed the accumulation of acetic butyric and propionic acids. Addition of carbohydrates, methylated amines and other methane precursors were found to stimulate methanogensis at low concentration (0.1%) carbohydrates, (1mM) methylated amines and methane precursors as compared to their higher concentrations. The phase contrast and fluorescence microscopic examinations showed the diverse microbial population of digestor contents. (author)

Martian methane plume models for defining Mars rover methane source search strategies

Science.gov (United States)

Nicol, Christopher; Ellery, Alex; Lynch, Brian; Cloutis, Ed

2018-07-01

The detection of atmospheric methane on Mars implies an active methane source. This introduces the possibility of a biotic source with the implied need to determine whether the methane is indeed biotic in nature or geologically generated. There is a clear need for robotic algorithms which are capable of manoeuvring a rover through a methane plume on Mars to locate its source. We explore aspects of Mars methane plume modelling to reveal complex dynamics characterized by advection and diffusion. A statistical analysis of the plume model has been performed and compared to analyses of terrestrial plume models. Finally, we consider a robotic search strategy to find a methane plume source. We find that gradient-based techniques are ineffective, but that more sophisticated model-based search strategies are unlikely to be available in near-term rover missions.

Atmospheric methane removal by methane-oxidizing bacteria immobilized on porous building materials

NARCIS (Netherlands)

Ganendra, G; De Muynck, W; Ho, A.; Hoefman, S.; De Vos, P.; Boeckx, P.; Boon, N.

2014-01-01

Biological treatment using methane-oxidizing bacteria (MOB) immobilized on six porous carrier materials have been used to mitigate methane emission. Experiments were performed with different MOB inoculated in building materials at high (similar to 20 % (v/v)) and low (similar to 100 ppmv) methane

Response of the Black Sea methane budget to massive short-term submarine inputs of methane

DEFF Research Database (Denmark)

Schmale, O.; Haeckel, M.; McGinnis, D. F.

2011-01-01

A steady state box model was developed to estimate the methane input into the Black Sea water column at various water depths. Our model results reveal a total input of methane of 4.7 Tg yr(-1). The model predicts that the input of methane is largest at water depths between 600 and 700 m (7......% of the total input), suggesting that the dissociation of methane gas hydrates at water depths equivalent to their upper stability limit may represent an important source of methane into the water column. In addition we discuss the effects of massive short-term methane inputs (e. g. through eruptions of deep......-water mud volcanoes or submarine landslides at intermediate water depths) on the water column methane distribution and the resulting methane emission to the atmosphere. Our non-steady state simulations predict that these inputs will be effectively buffered by intense microbial methane consumption...

Methane oxidation and methane fluxes in the ocean surface layer and deep anoxic waters

Science.gov (United States)

Ward, B. B.; Kilpatrick, K. A.; Novelli, P. C.; Scranton, M. I.

1987-01-01

Measured biological oxidation rates of methane in near-surface waters of the Cariaco Basin are compared with the diffusional fluxes computed from concentration gradients of methane in the surface layer. Methane fluxes and oxidation rates were investigated in surface waters, at the oxic/anoxic interface, and in deep anoxic waters. It is shown that the surface-waters oxidation of methane is a mechanism which modulates the flux of methane from marine waters to the atmosphere.

Coalbed Methane Outreach Program

Science.gov (United States)

Coalbed Methane Outreach Program, voluntary program seeking to reduce methane emissions from coal mining activities. CMOP promotes profitable recovery/use of coal mine methane (CMM), addressing barriers to using CMM instead of emitting it to atmosphere.

THE IMPACT OF EXTRUSION ON THE BIOGAS AND BIOMETHANE YIELD OF PLANT SUBSTRATES

Directory of Open Access Journals (Sweden)

Krzysztof Pilarski

2016-09-01

Full Text Available The objective of the present work was to determine the effect of pretreatment by extrusion on the biogas and biomethane yield of lignocellulosic substrates such as maize silage and maize straw silage. The biogas yields of the substrates before and after treatment were compared. Moreover, energy efficiency of pretreatment by extrusion was analyzed in order to assess the applicability of the process in an agricultural biogas plant. Extrusion tests were carried out in a short single-screw extruder KZM-2 in which the length-to-diameter ratio of the screw was 6:1 and rotational speed was 200 rpm. The biogas yield tests of the plant substrates after extrusion were carried out in a laboratory scale, using 15 biofermenters operated in a periodic manner, at a constant temperature of 39°C (mesophilic digestion and controlled pH conditions. The gas-emission analysis was performed using a certified gas analyzer from Geotech GA5000. Pretreatment by extrusion was observed to improve the quantity of methane generated: in terms of fresh matter for maize silage subjected to extrusion, the methane yield was 16.48% higher than that of the non-extruded silage. On the other hand, maize straw silage after extrusion gave 35.30% more methane than did the same, non-extruded, material. Differences in yields relative to dry organic matter are also described in this paper. Taking into account the amount of energy that is spent on pretreatment and the generated amount of methane, the energy balance for the process gives an idea of the economics of the operation. For maize silage, energy efficiency was lower by 13.21% (-553.2 kWh/Mg, in contrast to maize straw silage, where the increase in energy was 33.49% (678.4 kWh/Mg. The obtained results indicate that more studies on the pretreatment and digestion of maize silage are required in order to improve the efficiency of its use for making biogas. To fully utilize its potential, it is necessary to know thoroughly the effect of

Improved methane removal in exhaust gas from biogas upgrading process using immobilized methane-oxidizing bacteria.

Science.gov (United States)

Sun, Meng-Ting; Yang, Zhi-Man; Fu, Shan-Fei; Fan, Xiao-Lei; Guo, Rong-Bo

2018-05-01

Methane in exhaust gas from biogas upgrading process, which is a greenhouse gas, could cause global warming. The biofilter with immobilized methane-oxidizing bacteria (MOB) is a promising approach for methane removal, and the selections of inoculated MOB culture and support material are vital for the biofilter. In this work, five MOB consortia were enriched at different methane concentrations. The MOB-20 consortium enriched at the methane concentration of 20.0% (v/v) was then immobilized on sponge and two particle sizes of volcanic rock in biofilters to remove methane in exhaust gas from biogas upgrading process. Results showed that the immobilized MOB performed more admirable methane removal capacity than suspended cells. The immobilized MOB on sponge reached the highest methane removal efficiency (RE) of 35%. The rough surface, preferable hydroscopicity, appropriate pore size and particle size of support material might favor the MOB immobilization and accordingly methane removal. Copyright © 2018 Elsevier Ltd. All rights reserved.

The dream of an ultimate theory

International Nuclear Information System (INIS)

Weinberg, S.

1997-10-01

Steven Weinberg describes how the dream of an ultimate theory began when one tried to unify the fundamental laws governing the stars constellations as elementary particles: electromagnetism, weak-electro theory then standard model which gives only one quantity out of its fields, the gravitation. He tries to explain to what an ultimate theory could look like. but the dream of an ultimate theory is not yet realized, there are some elementary particles to find before and then to build superconducting super colliders. The europe made it. the dream of an ultimate theory became an european dream. (N.C.)

Project identification for methane reduction options

Energy Technology Data Exchange (ETDEWEB)

Kerr, T.

1996-12-31

This paper discusses efforts directed at reduction in emission of methane to the atmosphere. Methane is a potent greenhouse gas, which on a 20 year timeframe may present a similar problem to carbon dioxide. In addition, methane causes additional problems in the form of smog and its longer atmospheric lifetime. The author discusses strategies for reducing methane emission from several major sources. This includes landfill methane recovery, coalbed methane recovery, livestock methane reduction - in the form of ruminant methane reduction and manure methane recovery. The author presents examples of projects which have implemented these ideas, the economics of the projects, and additional gains which come from the projects.

A novel integrated process of coal pyrolysis and methane CO{sub 2} reforming

Energy Technology Data Exchange (ETDEWEB)

Jing Wang; Pengfei Wang; Lijun Jin; Haoquan Hu [Dalian University of Technology, Dalian (China)

2007-07-01

In the paper, a novel pyrolysis method, namely coal pyrolysis coupling with CO{sub 2} reforming of methane (CRMP) or catalytic pyrolysis of coal coupling with CO{sub 2} reforming of methane (CRMCP), for improving the tar yield of coal pyrolysis was introduced. The behaviours of YM coal in both processes were investigated and compared with pyrolysis under N{sub 2} and H{sub 2}. The results show that the tar yield of coal pyrolysis in both processes obviously increase compared with that in N{sub 2} or H{sub 2}. When YM coal pyrolysis was carried out in stream of mixture gas CH{sub 4}/CO{sub 2} (1:1) with the existence of the catalyst at 0.1 MPa and 800{sup o}C, the tar yield is 2.8 times for CRMP and 4.3 times for CRMCP as that of pyrolysis under N{sub 2} and 1.7 and 2.6 times as that of hydropyrolysis at the same conditions, respectively. Sulfur content of char obtained from CRMP and CRMCP process are lower, especially in CRMP process, than that from N{sub 2} or H{sub 2}. 16 refs., 4 figs., 1 tab.

Dry Reforming of Methane Using a Nickel Membrane Reactor

Directory of Open Access Journals (Sweden)

Jonas M. Leimert

2017-12-01

Full Text Available Dry reforming is a very interesting process for synthesis gas generation from CH 4 and CO 2 but suffers from low hydrogen yields due to the reverse water–gas shift reaction (WGS. For this reason, membranes are often used for hydrogen separation, which in turn leads to coke formation at the process temperatures suitable for the membranes. To avoid these problems, this work shows the possibility of using nickel self-supported membranes for hydrogen separation at a temperature of 800 ∘ C. The higher temperature effectively suppresses coke formation. The paper features the analysis of the dry reforming reaction in a nickel membrane reactor without additional catalyst. The measurement campaign targeted coke formation and conversion of the methane feedstock. The nickel approximately 50% without hydrogen separation. The hydrogen removal led to an increase in methane conversion to 60–90%.

Optimization of separate hydrogen and methane production from cassava wastewater using two-stage upflow anaerobic sludge blanket reactor (UASB) system under thermophilic operation.

Science.gov (United States)

Intanoo, Patcharee; Rangsanvigit, Pramoch; Malakul, Pomthong; Chavadej, Sumaeth

2014-12-01

The objective of this study was to investigate the separate hydrogen and methane productions from cassava wastewater by using a two-stage upflow anaerobic sludge blanket (UASB) system under thermophilic operation. Recycle ratio of the effluent from methane bioreactor-to-feed flow rate was fixed at 1:1 and pH of hydrogen UASB unit was maintained at 5.5. At optimum COD loading rate of 90 kg/m3 d based on the feed COD load and hydrogen UASB volume, the produced gas from the hydrogen UASB unit mainly contained H2 and CO2 which provided the maximum hydrogen yield (54.22 ml H2/g COD applied) and specific hydrogen production rate (197.17 ml/g MLVSSd). At the same optimum COD loading rate, the produced gas from the methane UASB unit mainly contained CH4 and CO2 without H2 which were also consistent with the maximum methane yield (164.87 ml CH4/g COD applied) and specific methane production rate (356.31 ml CH4/g MLVSSd). The recycling operation minimized the use of NaOH for pH control in hydrogen UASB unit. Copyright © 2014 Elsevier Ltd. All rights reserved.

Characterisation of water hyacinth with microwave-heated alkali pretreatment for enhanced enzymatic digestibility and hydrogen/methane fermentation.

Science.gov (United States)

Lin, Richen; Cheng, Jun; Song, Wenlu; Ding, Lingkan; Xie, Binfei; Zhou, Junhu; Cen, Kefa

2015-04-01

Microwave-heated alkali pretreatment (MAP) was investigated to improve enzymatic digestibility and H2/CH4 production from water hyacinth. SEM revealed that MAP deconstructed the lignocellulose matrix and swelled the surfaces of water hyacinth. XRD indicated that MAP decreased the crystallinity index from 16.0 to 13.0 because of cellulose amorphisation. FTIR indicated that MAP effectively destroyed the lignin structure and disrupted the crystalline cellulose to reduce crystallinity. The reducing sugar yield of 0.296 g/gTVS was achieved at optimal hydrolysis conditions (microwave temperature = 190°C, time = 10 min, and cellulase dosage = 5 wt%). The sequentially fermentative hydrogen and methane yields from water hyacinth with MAP and enzymatic hydrolysis were increased to 63.9 and 172.5 mL/gTVS, respectively. The energy conversion efficiency (40.0%) in the two-stage hydrogen and methane cogeneration was lower than that (49.5%) in the one-stage methane production (237.4 mL/gTVS) from water hyacinth with MAP and enzymatic hydrolysis. Copyright © 2015 Elsevier Ltd. All rights reserved.

Development of Vanadium Phosphaate Catalysts for Methanol Production by Selective Oxidation of Methane.

Energy Technology Data Exchange (ETDEWEB)

McCormick, R.L.

1997-10-01

This DOE sponsored study of methane partial oxidation was initiated at Amax Research and Development in Golden, CO in October of 1993. Shortly thereafter the management of Amax closed this R&D facility and the PI moved to the Colorado School of Mines. The project was begun again after contract transfer via a novation agreement. Experimental work began with testing of vandyl pyrophosphate (VPO), a well known alkane selective oxidation catalyst. It was found that VPO was not a selective catalyst for methane conversion yielding primarily CO. However, promotion of VPO with Fe, Cr, and other first row transition metals led to measurable yields for formaldehyde, as noted in the summary table. Catalyst characterization studies indicated that the role of promoters was to stabilize some of the vanadium in the V{sup 5+} oxidation state rather than the V{sup 4+} state formally expected for (VO){sub 2}P{sub 2}O{sub 7}.

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

The potential of methane-oxidizing bacteria for applications in environmental biotechnology

Energy Technology Data Exchange (ETDEWEB)

Wendlandt, Karin-Dagmar; Stottmeister, Ulrich; Jechorek, Mirko [Helmholtz-Center for Environmental Research UFZ, Leipzig (Germany); Helm, Jana [School of Physics and Astronomy, The University of Edinburgh, Edinburgh (United Kingdom); Soltmann, Bettina [Institute for Materials Science, Dresden University of Technology, Dresden (Germany); Beck, Matthias [Oncotec, Pharma Production GmbH, Dessau-Rosslau (Germany)

2010-04-15

Methanotrophic bacteria possess a unique set of enzymes enabling them to oxidize, degrade and transform organic molecules and synthesize new compounds. Therefore, they have great potential in environmental biotechnology. The application of these unique properties was demonstrated in three case studies: (i) Methane escaping from leaky gas pipes may lead to massive mortality of trees in urban areas. Lack of oxygen within the soil surrounding tree roots caused by methanotrophic activity was identified as one of the reasons for this phenomenon. The similarity between metabolic reactions performed by the key enzymes of methanotrophs (methane monooxygenase) and ammonium oxidizers (ammonium monooxygenase) might offer a solution to this problem by applying commercially available nitrification and urease inhibitors. (ii) Methanotrophs are able to co-metabolically degrade contaminants such as low-molecular-weight-chlorinated hydrocarbons in soil and water in the presence of methane. Batch and continuous trichloroethylene degradation experiments in laboratory-scale reactors using Methylocystis sp. GB 14 were performed, partly with cells entrapped in a polymer matrix. (iii) Using a short, two-stage pilot-scale process, the intracellular polymer accumulation of poly-{beta}-hydroxybutyrate (PHB) in methanotrophs reached a maximum of 52%. Interestingly, an ultra-high-molecular-weight PHB of 3.1 MDa was accumulated under potassium deficiency. Under strictly controlled conditions (temperature, pH and methane supply) this process can be nonsterile because of the establishment of a stable microbial community (dominant species Methylocystis sp. GB 25 {>=}86% by biomass). The possibility to substitute methane with biogas from renewable sources facilitates the development of a methane-based PHB production process that yields a high-quality biopolymer at competitive costs. (Abstract Copyright [2010], Wiley Periodicals, Inc.)

Photo-stimulated desorption from water and methane clusters on the surface of solid neon

International Nuclear Information System (INIS)

Arakawa Ichiri; Matsumoto Dairo; Takekuma Shinichi; Tamura Reimi; Miura Takashi

2012-01-01

Photo-stimulated desorption of ions from methane and water heterocluster on the surface of solid neon was studied. The desorption yields of the variety of photo-desorbed species showed strong dependence on the composition and the size of the mother cluster. It was found that the presence of a water molecule in the cluster significantly enhanced, or was almost essential for, the desorption of any species observed. Systematic investigation of the correlation between the cluster size and the desorption yield of each ion has revealed the mother cluster which yields the each desorbed ion.

Influence of biogenic gas production on coalbed methane recovery index

Directory of Open Access Journals (Sweden)

Hongyu Guo

2017-05-01

Full Text Available In investigating the effect of biogenic gas production on the recovery of coalbed methane (CBM, coal samples spanning different ranks were applied in the microbial-functioned simulation experiments for biogenic methane production. Based on the biogenic methane yield, testing of pore structures, and the isothermal adsorption data of coals used before and after the simulation experiments, several key parameters related to the recovery of CBM, including recovery rate, gas saturation and ratio of critical desorption pressure to reservoir pressure, etc., were calculated and the corresponding variations were further analyzed. The results show that one of the significant functions of microbial communities on coal is possibly to weaken its affinity for methane gas, especially with the advance of coal ranks; and that by enhancing the pore system of coal, which can be evidenced by the increase of porosity and permeability, the samples collected from Qianqiu (Yima in Henan and Shaqu (Liulin in Shanxi coal mines all see a notable increase in the critical desorption pressure, gas saturation and recovery rate, as compared to the moderate changes of that of Guandi (Xishan in Shanxi coal sample. It is concluded that the significance of enhanced biogenic gas is not only in the increase of CBM resources and the improvement of CBM recoverability, but in serving as an engineering reference for domestic coalbed biogenic gas production.

Two Mechanisms for Methane Release at the Paleocene/Eocene Boundary

Science.gov (United States)

Katz, M. E.; Cramer, B. S.; Mountain, G. S.; Mountain, G. S.; Katz, S.; Miller, K. G.; Miller, K. G.

2001-12-01

The rapid global warming of the Paleocene/Eocene thermal maximum (PETM) has been attributed to a massive methane release from marine gas hydrate reservoirs. Two mechanisms have been proposed for this methane release. The first relies on a deepwater circulation change and water temperature increase that was sufficiently large and rapid to trigger massive thermal dissociation of gas hydrate frozen beneath the seafloor (Dickens et al., 1995). The second relies on slope failure (via erosion or seismic activity) of the oversteepened continental margins of the western North Atlantic to allow methane to escape from gas reservoirs trapped between the hydrate-bearing sediments and the underlying reef front (Katz et al., in press). We evaluate thermal dissociation by modeling heat flow through the sediments to show the effect of the temperature change on the gas hydrate stability zone through time. We use Paleocene bottom water temperatures (constrained by isotope records) and assume an instantaneous water temperature increase (i.e., no time allotted for ocean circulation change and water mass mixing). This yields an end-member minimum estimate of >2350 years necessary to melt all gas hydrate at locations shallower than 1570m; gas hydrates at greater depths remain frozen. We also use this model to predict the amount of C12-enriched methane that could have contributed to the carbon isotope excursion (CIE). Using reasonable methane distributions within sediments, we conclude that thermal dissociation alone cannot account for the full magnitude of the CIE. We propose that thermal dissociation did not initiate the CIE; rather, a different mechanism injected a large amount of carbon into the atmosphere, causing global greenhouse warming that could have led to subsequent thermal dissociation. Methane remains a plausible source for this initial carbon injection; however, initial release would have resulted from mechanical disruption of sediments rather than thermal dissociation

Global Methane Initiative

Science.gov (United States)

The Global Methane Initiative promotes cost-effective, near-term methane recovery through partnerships between developed and developing countries, with participation from the private sector, development banks, and nongovernmental organizations.

Concussion Prevalence in Competitive Ultimate Frisbee Players

Science.gov (United States)

Lazar, Damien J.; Lichtenstein, Jonathan D.; Tybor, David J.

2018-01-01

Background: Ultimate Frisbee (ultimate) is a fast-growing, popular sport played nationally by over 4 million athletes. While several studies have examined injury rates in ultimate, no work has investigated the prevalence of concussions specifically or players’ knowledge and management of those injuries. Purpose: To estimate the lifetime prevalence of concussions in ultimate and to assess players’ knowledge of concussions as well as their concussion management behaviors. Study Design: Descriptive epidemiology study. Methods: From June to November 2015, we collected ultimate-related concussion data via an anonymous web-based survey, the Concussion in Ultimate Frisbee Survey, from a convenience sample of 787 male and female ultimate players across the United States. Results: There were 553 male and 234 female respondents included in the analysis; 26.58% of men and 24.79% of women reported that they had sustained at least 1 concussion while playing ultimate, with 45.58% and 43.10% of those men and women, respectively, reporting multiple concussions. A total of 67.81% of men and 78.21% of women stated that they would remove themselves from play after sustaining a given concussion, although 45.99% of men and 37.62% of women indicated that they had returned to play in the same game or practice. Conclusion: Our preliminary data suggest that concussions do commonly occur in competitive ultimate and that better education and management of concussions in ultimate athletes are needed. This study is an important first step in deepening our understanding of these issues. PMID:29552572

Effect of VS organic loads and buckwheat husk on methane production by anaerobic co-digestion of primary sludge and wheat straw

International Nuclear Information System (INIS)

Elsayed, Mahmoud; Andres, Yaves; Blel, Walid; Gad, Ali; Ahmed, Abdelkader

2016-01-01

Highlights: • Co-digestion of PS, WS, and BH was conducted to evaluate different VS organic loads for an optimal methane production. • Co-digestion of PS and WS was optimized using buckwheat husk as a new waste material. • Combination of PS, WS, and BH produced higher methane yields than the individual digestion of PS, WS, and BH. • The highest CMYs and VS removal rate were achieved at C/N ratios of 10 and 7.50 gVS/L, respectively. • The purification process increased the methane content from 58.91–63.05% to 92.46–95.30%. - Abstract: An environmentally acceptable disposal of sewage sludge and agro-wastes presents an urgent problem facing many countries. Anaerobic digestion (AD) is a robust and suitable technique for producing renewable energy from wastes. This study aims to improve methane production from anaerobic co-digestion of primary sludge (PS) and wheat straw (WS) depending on their volatile solids (VS) organic load and by adding a proposed waste material of buckwheat husk (BH) based on their carbon to nitrogen (C/N) ratio. Mesophilic anaerobic batch tests were carried out in 500-mL digesters. Individual and six mixtures of PS and WS at different VS organic loads were anaerobically digested to optimize VS load for the greatest gas production. The highest cumulative methane yield (CMYs) occurred with combined substrates at a VS load of 7.50 gVS/L. In general, the optimized organic loads that gave the highest cumulative biogas yield (CBYs) and CMYs were in the range of 6–8 gVS/L. In addition, AD of individual substrates of PS, WS, and BH and of their mixture at different C/N ratios was investigated regarding to the methane yields. Multi-component substrates produced the greatest CMY at a C/N ratio of 10.07. The CMYs was increased by 39.26% when the proposed waste material of buckwheat husk (BH) was added to the different mixtures of PS and WS compared to the co-digestion of PS and WS. Experimental results were approved using statistical

Determining the flux of methane into Hudson Canyon at the edge of methane clathrate hydrate stability

Science.gov (United States)

Weinsten, A.; Navarrete, L; Ruppel, Carolyn D.; Weber, T.C.; Leonte, M.; Kellermann, M.; Arrington, E.; Valentine, D.L.; Scranton, M.L; Kessler, John D.

2016-01-01

Methane seeps were investigated in Hudson Canyon, the largest shelf-break canyon on the northern US Atlantic Margin. The seeps investigated are located at or updip of the nominal limit of methane clathrate hydrate stability. The acoustic identification of bubble streams was used to guide water column sampling in a 32 km2 region within the canyon's thalweg. By incorporating measurements of dissolved methane concentration with methane oxidation rates and current velocity into a steady-state box model, the total emission of methane to the water column in this region was estimated to be 12 kmol methane per day (range: 6 – 24 kmol methane per day). These analyses suggest this methane is largely retained inside the canyon walls below 300 m water depth, and that it is aerobically oxidized to near completion within the larger extent of Hudson Canyon. Based on estimated methane emissions and measured oxidation rates, the oxidation of this methane to dissolved CO2 is expected to have minimal influences on seawater pH. This article is protected by copyright. All rights reserved.

Effects of diet forage source and neutral detergent fiber content on milk production of dairy cattle and methane emissions determined using GreenFeed and respiration chamber techniques.

Science.gov (United States)

Hammond, K J; Jones, A K; Humphries, D J; Crompton, L A; Reynolds, C K

2016-10-01

Strategies to mitigate greenhouse gas emissions from dairy cattle are unlikely to be adopted if production or profitability is reduced. The primary objective of this study was to examine the effects of high maize silage (MS) versus high grass silage (GS) diets, without or with added neutral detergent fiber (NDF) on milk production and methane emission of dairy cattle, using GreenFeed (GF) or respiration chamber (RC) techniques for methane emission measurements. Experiment 1 was 12wk in duration with a randomized block continuous design and 40 Holstein cows (74d in milk) in free-stall housing, assigned to 1 of 4 dietary treatments (n=10 per treatment), according to calving date, parity, and milk yield. Milk production and dry matter intake (DMI) were measured daily, and milk composition measured weekly, with methane yield (g/kg of DMI) estimated using a GF unit (wk 10 to 12). Experiment 2 was a 4×4 Latin square design with 5-wk periods and 4 dairy cows (114d in milk) fed the same 4 dietary treatments as in experiment 1. Measurements of DMI, milk production, and milk composition occurred in wk 4, and DMI, milk production, and methane yield were measured for 2d in RC during wk 5. Dietary treatments for both experiments were fed as total mixed rations offered ad libitum and containing 500g of silage/kg of dry matter composed (DM basis) of either 75:25 MS:GS (MS) or 25:75 MS:GS (GS), without or with added NDF from chopped straw and soy hulls (+47g of NDF/kg of dry matter). In both experiments, compared with high GS, cows fed high MS had a higher DMI, greater milk production, and lower methane yield (24% lower in experiment 1 using GF and 8% lower in experiment 2 using RC). Added NDF increased (or tended to increase) methane yield for high MS, but not high GS diets. In the separate experiments, the GF and RC methods detected similar dietary treatment effects on methane emission (expressed as g/d and g/kg of DMI), although the magnitude of the differences varied between

The ultimate quotable Einstein

CERN Document Server

2011-01-01

Here is the definitive new edition of the hugely popular collection of Einstein quotations that has sold tens of thousands of copies worldwide and been translated into twenty-five languages. The Ultimate Quotable Einstein features 400 additional quotes, bringing the total to roughly 1,600 in all. This ultimate edition includes new sections--"On and to Children," "On Race and Prejudice," and "Einstein's Verses: A Small Selection"--as well as a chronology of Einstein's life and accomplishments, Freeman Dyson's authoritative foreword, and new commentary by Alice Calaprice.

Intravenous lipid infusion affects dry matter intake, methane yield, and rumen bacteria structure in late-lactating Holstein cows.

Science.gov (United States)

Lamp, Ole; Reyer, Henry; Otten, Winfried; Nürnberg, Gerd; Derno, Michael; Wimmers, Klaus; Metges, Cornelia C; Kuhla, Björn

2018-03-28

Increasing the dietary fat content of ruminant diets decreases methane (CH 4 ) production. This effect is caused by the toxic properties of fatty acids on rumen microbial populations, coating of feed particles diminishing the accessibility for microbes, and a reduction in dry matter intake (DMI). The latter effect is caused by postabsorptive long-chain fatty acids eliciting anorexic signaling; however, whether circulating long-chain fatty acids affect rumen CH 4 production alike is unknown. To approach this question, 5 rumen-cannulated Holstein cows in late lactation received 2 jugular catheters and were kept in respiration chambers to measure CH 4 production and DMI for 48 h. In a crossover design, cows were intravenously infused with a 20% lipid emulsion (LIPO) or 0.9% NaCl (CON). The LIPO cows received 2.1 kg of triglycerides/d [0.152 ± 0.007 g of triglycerides/(kg of BW × h) -1 ] consisting of 12.1% palmitic acid, 4.2% stearic acid, 31.1% oleic acid, and 52.7% linoleic acid. Blood and rumen fluid samples were taken hourly during the day. Results showed that LIPO compared with CON infusion increased plasma triglyceride as well as free fatty acid and serotonin concentrations but reduced the proportion of de novo synthesized milk fatty acids (sum of C6 to C16). Daily CH 4 production and DMI were lower, whereas daily CH 4 yield (CH 4 /DMI) was greater in LIPO than CON cows, although CH 4 yield decreased from d 1 to d 2 by 2 to 14% in LIPO-infused cows only. This effect was associated with a higher (acetate + butyrate)/propionate ratio, tending lower propionate concentrations between 24 and 34 h of infusion, reduced relative abundances of genera belonging to Succinivibrio, Ruminococcaceae, and Ruminiclostridium, and greater relative Bacteroidetes genus abundances in the rumen. Copyright © 2018 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Methane and fertilizer production from seaweed biomass. Final report

Energy Technology Data Exchange (ETDEWEB)

Betzer, P.R.; Humm, H.J.

1984-01-01

It was demonstrated that several varieties of abundant benthic algae indigenous to Tampa Bay (Gracilaria, Hypnea, and Ulva) were readily degradable via anaerobic digestion to methane. The energy yield per unit weight biomass degraded was higher than any previously reported. Given the large masses of readily degradable plants which are annually produced in and around Tampa Bay, the resource is estimated to be at least equivalent to several million gallons of gasoline.

Production of ethanol, fat and oil and methane gas from several crops. Sushu sakumotsu nado no energygen toshite no hyoka

Energy Technology Data Exchange (ETDEWEB)

Uehara, Tsuyoshi; Suganuma, Hirotoshi

1988-05-01

Aiming at production of ethanol, fat and oil and so on, ten kinds of miscellaneous cereal crops such as pearl-millet, soybean and so on were grown, and comparative investigation of the production rate which was considered utilization of whole plants were carried out. The suitability of vegetable wastes as methane fermentation materials for the methane gas production was investigated by the constituent analyses and methane fermentation experiments. Nine kinds of the grasses and vegetable wastes such as tomatoe buds, broccoli leaves were used for the investigation. As the results, the estimated yield of ethanol per 10 are from pearl-millet was 690 liter, the estimated yield of fat and oil per 10 are was 70 liter from soybean, The results of the analyses of nine kinds of the farm residues were as follows: (1) carbon content of about 40 %, (2) C/N ratio of 13 av., (3) C/P ratio of 91 av., and (4) the content of C,N and P was roughly appropriate. 680 to 760 milliliter of methane gas was produced from one gram of the dry matter of tomatoe bods, and in case of broccoli leaves, 424 milliliter of methane gas was produced, it was found that these values were not inferior to animal dung. (4 figs, 15 tabs, 6 refs)

Uncertainty assessment of the breath methane concentration method to determine methane production of dairy cows

NARCIS (Netherlands)

Wu, Liansun; Groot Koerkamp, Peter W.G.; Ogink, Nico

2018-01-01

The breath methane concentration method uses the methane concentrations in the cow's breath during feed bin visits as a proxy for the methane production rate. The objective of this study was to assess the uncertainty of a breath methane concentration method in a feeder and its capability to measure

Biocatalytic conversion of methane to methanol as a key step for development of methane-based biorefineries.

Science.gov (United States)

Hwang, In Yeub; Lee, Seung Hwan; Choi, Yoo Seong; Park, Si Jae; Na, Jeong Geol; Chang, In Seop; Kim, Choongik; Kim, Hyun Cheol; Kim, Yong Hwan; Lee, Jin Won; Lee, Eun Yeol

2014-12-28

Methane is considered as a next-generation carbon feedstock owing to the vast reserves of natural and shale gas. Methane can be converted to methanol by various methods, which in turn can be used as a starting chemical for the production of value-added chemicals using existing chemical conversion processes. Methane monooxygenase is the key enzyme that catalyzes the addition of oxygen to methane. Methanotrophic bacteria can transform methane to methanol by inhibiting methanol dehydrogenase. In this paper, we review the recent progress made on the biocatalytic conversion of methane to methanol as a key step for methane-based refinery systems and discuss future prospects for this technology.

Effect of technical cashew nut shell liquid on rumen methane emission and lactation performance of dairy cows.

Science.gov (United States)

Branco, A F; Giallongo, F; Frederick, T; Weeks, H; Oh, J; Hristov, A N

2015-06-01

Technical-grade cashew nut shell liquid (TCNSL) is a by-product of the cashew nut industry in tropical countries, and is known to exhibit a wide range of biological activities, including inhibitory effect against gram-positive bacteria. This study was conducted to investigate the effects of TCNSL (73.3% cardanol, 16.4% cardol, and 3.0% methylcardol) on rumen methane emission, nutrient digestibility, dry matter intake, and milk yield and composition in dairy cows. Eight multiparous Holstein cows were used in a crossover design trial with two 21-d experimental periods. The diet was based on corn silage and alfalfa haylage and was formulated to meet or exceed the energy and metabolizable protein requirements of the cows. Treatments were control (no TCNSL supplementation) or 30 g/cow per day of TCNSL. Rumen carbon dioxide emission was not affected by TCNSL. Treatment had no effect on methane emission (542 vs. 511±35.3 g/cow per day, respectively) and methane emission intensity (15.0 vs. 13.9±0.58 g/kg of energy-corrected milk, respectively) and tended to decrease methane emission per kilogram of dry matter intake (20.2 vs. 18.6±1.04 g/kg, respectively). Dry matter intake (average 26.9±1.00 kg/d), milk yield (40.0±1.73 kg/d), and milk composition were not different between treatments. The TCNSL had no effect on N losses in urine and feces and total-tract apparent digestibility of nutrients, except digestibility of neutral detergent fiber tended to be increased compared with the control. Plasma urea and glucose concentrations were not affected by TCNSL. Concentration of milk C18:0 tended to be decreased (17%) by TCNSL compared with the control. In this study, TCNSL did not alter absolute methane emission in the rumen, but tended to decrease it by 8% per kilogram of dry matter intake. The TCNSL had no effect on milk yield and composition in dairy cows. Copyright © 2015 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

An integrated system for hydrogen and methane production during landfill leachate treatment

Energy Technology Data Exchange (ETDEWEB)

Hafez, Hisham; Nakhla, George; El Naggar, Hesham [Civil and Environmental Engineering Department, University of Western Ontario, London, Ontario (Canada)

2010-05-15

The patent-pending integrated waste-to-energy system comprises both a novel biohydrogen reactor with a gravity settler (Biohydrogenator), followed by a second stage conventional anaerobic digester for the production of methane gas. This chemical-free process has been tested with a synthetic wastewater/leachate solution, and was operated at 37 C for 45 d. The biohydrogenator (system (A), stage 1) steadily produced hydrogen with no methane during the experimental period. The maximum hydrogen yield was 400 mL H{sub 2}/g glucose with an average of 345 mL H{sub 2}/g glucose, as compared to 141 and 118 mL H{sub 2}/g glucose for two consecutive runs done in parallel using a conventional continuously stirred tank reactor (CSTR, System (B)). Decoupling of the solids retention time (SRT) from the hydraulic retention time (HRT) using the gravity settler showed a marked improvement in performance, with the maximum and average hydrogen production rates in system (A) of 22 and 19 L H{sub 2}/d, as compared with 2-7 L H{sub 2}/d in the CSTR resulting in a maximum yield of 2.8 mol H{sub 2}/mol glucose much higher than the 1.1-1.3 mol H{sub 2}/mol glucose observed in the CSTR. Furthermore, while the CSTR collapsed in 10-15 d due to biomass washout, the biohydrogenator continued stable operation for the 45 d reported here and beyond. The methane yield for the second stage in system (A) approached a maximum value of 426 mL CH{sub 4}/gCOD removed, while an overall chemical oxygen demand (COD) removal efficiency of 94% was achieved in system (A). (author)

Effect of bioaugmentation by cellulolytic bacteria enriched from sheep rumen on methane production from wheat straw.

Science.gov (United States)

Ozbayram, E Gozde; Kleinsteuber, Sabine; Nikolausz, Marcell; Ince, Bahar; Ince, Orhan

2017-08-01

The aim of this study was to determine the potential of bioaugmentation with cellulolytic rumen microbiota to enhance the anaerobic digestion of lignocellulosic feedstock. An anaerobic cellulolytic culture was enriched from sheep rumen fluid using wheat straw as substrate under mesophilic conditions. To investigate the effects of bioaugmentation on methane production from straw, the enrichment culture was added to batch reactors in proportions of 2% (Set-1) and 4% (Set-2) of the microbial cell number of the standard inoculum slurry. The methane production in the bioaugmented reactors was higher than in the control reactors. After 30 days of batch incubation, the average methane yield was 154 mL N CH 4 g VS -1 in the control reactors. Addition of 2% enrichment culture did not enhance methane production, whereas in Set-2 the methane yield was increased by 27%. The bacterial communities were examined by 454 amplicon sequencing of 16S rRNA genes, while terminal restriction fragment length polymorphism (T-RFLP) fingerprinting of mcrA genes was applied to analyze the methanogenic communities. The results highlighted that relative abundances of Ruminococcaceae and Lachnospiraceae increased during the enrichment. However, Cloacamonaceae, which were abundant in the standard inoculum, dominated the bacterial communities of all batch reactors. T-RFLP profiles revealed that Methanobacteriales were predominant in the rumen fluid, whereas the enrichment culture was dominated by Methanosarcinales. In the batch rectors, the most abundant methanogens were affiliated to Methanobacteriales and Methanomicrobiales. Our results suggest that bioaugmentation with sheep rumen enrichment cultures can enhance the performance of digesters treating lignocellulosic feedstock. Copyright © 2017 Elsevier Ltd. All rights reserved.

Bioelectrochemical methane (CH4) production in anaerobic digestion at different supplemental voltages.

Science.gov (United States)

Choi, Kwang-Soon; Kondaveeti, Sanath; Min, Booki

2017-12-01

Microbial electrolysis cells (MECs) at various cell voltages (0.5, 0.7 1.0 and 1.5V) were operated in anaerobic fermentation. During the start-up period, the cathode potential decreased from -0.63 to -1.01V, and CH 4 generation increased from 168 to 199ml. At an applied voltage of 1.0V, the highest methane yields of 408.3ml CH 4 /g COD glucose was obtained, which was 30.3% higher than in the control tests (313.4ml CH 4 /g COD glucose). The average current of 5.1mA was generated at 1.0V at which the maximum methane yield was obtained. The other average currents were 1.42, 3.02, 0.53mA at 0.5, 0.7, and 1.5V, respectively. Cyclic voltammetry and EIS analysis revealed that enhanced reduction currents were present at all cell voltages with biocatalyzed cathode electrodes (no reduction without biofilm), and the highest value was obtained with 1V external voltage. Copyright © 2017 Elsevier Ltd. All rights reserved.

Marine biomass power plant using methane fermentation

Energy Technology Data Exchange (ETDEWEB)

Matsui, T.; Saito, H.; Amano, T.; Sugawara, H.; Seki, T.; Abe, T. [Technology Research Inst., Tokyo Gas Co. Ltd., Tokyo (Japan)

2004-07-01

This study presented an effective way to produce biogas from the large quantities of seaweed waste in Japan. A large-scale marine biomass pilot plant was built to produce biogas from marine biomass. Methane fermentation was the process used to produce biogas from Laminaria sp. The maximum treating capacity of the pilot plant is 1 ton of seaweed per day. The pilot plant includes a pretreatment facility, fermentation, biogas storage and power generation. The maximum methane yield from the biomass plant is 22 cubic ton-seaweed. The purified biogas has generated 10 kW of electricity and 23 kW of heat. The biogas was also mixed with natural gas for use in a gas engine generator. The engine operation remained stable despite changes in quantity and composition of the collected biogas caused by changes with the source of biomass and sea conditions. The thermal efficiency of the gas engine running on mixed biogas and natural gas was more than 10 per cent higher than an engine running on biogas fuel alone. 4 refs., 2 tabs., 3 figs.

Mechanics of coalbed methane production

Energy Technology Data Exchange (ETDEWEB)

Creel, J C; Rollins, J B [Crawley, Gillespie and Associates, Inc. (United Kingdom)

1994-12-31

Understanding the behaviour of coalbed methane reservoirs and the mechanics of production is crucial to successful management of coalbed methane resources and projects. This paper discusses the effects of coal properties and coalbed methane reservoir characteristics on gas production rates and recoveries with a review of completion techniques for coalbed methane wells. 4 refs., 17 figs.

Wheat is more potent than corn or barley for dietary mitigation of enteric methane emissions from dairy cows.

Science.gov (United States)

Moate, P J; Williams, S R O; Jacobs, J L; Hannah, M C; Beauchemin, K A; Eckard, R J; Wales, W J

2017-09-01

Wheat is the most common concentrate fed to dairy cows in Australia, but few studies have examined the effects of wheat feeding on enteric methane emissions, and no studies have compared the relative potencies of wheat, corn, and barley for their effects on enteric methane production. In this 35-d experiment, 32 Holstein dairy cows were offered 1 of 4 diets: a corn diet (CRN) of 10.0 kg of dry matter (DM)/d of single-rolled corn grain, 1.8 kg of DM/d of canola meal, 0.2 kg of DM/d of minerals, and 11.0 kg of DM/d of chopped alfalfa hay; a wheat diet (WHT) similar to the CRN diet but with the corn replaced by single-rolled wheat; a barley diet (SRB) similar to the CRN diet but with the corn replaced by single-rolled barley; and a barley diet (DRB) similar to the CRN diet but with the corn replaced by double-rolled barley. Individual cow feed intakes, milk yields, and milk compositions were measured daily but reported for the last 5 d of the experiment. During the last 5 d of the experiment, individual cow methane emissions were measured using the SF 6 tracer technique for all cows, and ruminal fluid pH was continuously measured by intraruminal sensors for 3 cows in each treatment group. The average DM intake of cows offered the CRN, WHT, SRB, and DRB diets was 22.2, 21.1, 22.6, and 22.6 kg/d. The mean energy-corrected milk of cows fed the WHT diet was less than that of cows fed the other diets. This occurred because the milk fat percentage of cows fed the WHT diet was significantly less than that of cows fed the other diets. The mean methane emissions and methane yields of cows fed the WHT diet were also significantly less than those of cows fed the other diets. Indeed, the CRN, SRB, and DRB diets were associated with 49, 73, and 78% greater methane emissions, respectively, compared with the emissions from the WHT diet. Methane yield was found to be most strongly related to the minimum daily ruminal fluid pH. This study showed that although the inclusion of wheat in

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

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.

Material Properties Test to Determine Ultimate Strain and True Stress-True Strain Curves for High Yield Steels

Energy Technology Data Exchange (ETDEWEB)

K.R. Arpin; T.F. Trimble

2003-04-01

This testing was undertaken to develop material true stress-true strain curves for elastic-plastic material behavior for use in performing transient analysis. Based on the conclusions of this test, the true stress-true strain curves derived herein are valid for use in elastic-plastic finite element analysis for structures fabricated from these materials. In addition, for the materials tested herein, the ultimate strain values are greater than those values cited as the limits for the elastic-plastic strain acceptance criteria for transient analysis.

Methane-fueled vehicles: A promising market for coalbed methane

International Nuclear Information System (INIS)

Deul, M.

1993-01-01

The most acceptable alternative fuel for motor vehicles is compressed natural gas (CNG). An important potential source of such gas is coalbed methane, much of which is now being wasted. Although there are no technological impediments to the use of CNG it has not been adequately promoted for a variety of reasons: structural, institutional and for coalbed gas, legal. The benefits of using CNG fuel are manifold: clean burning, low cost, abundant, and usable in any internal combustion engine. Even though more than 30,000 CNG vehicles are now in use in the U.S.A., they are not readily available, fueling stations are not easily accessible, and there is general apathy on the part of the public because of negligence by such agencies as the Department of Energy, the Department of Transportation and the Environmental Protection Agency. The economic benefits of using methane are significant: 100,000 cubic feet of methane is equivalent to 800 gallons of gasoline. Considering the many millions of cubic feet methane wasted from coal mines conservation and use of this resource is a worthy national goal

Methane Hydrates: Chapter 8

Science.gov (United States)

Boswell, Ray; Yamamoto, Koji; Lee, Sung-Rock; Collett, Timothy S.; Kumar, Pushpendra; Dallimore, Scott

2008-01-01

Gas hydrate is a solid, naturally occurring substance consisting predominantly of methane gas and water. Recent scientific drilling programs in Japan, Canada, the United States, Korea and India have demonstrated that gas hydrate occurs broadly and in a variety of forms in shallow sediments of the outer continental shelves and in Arctic regions. Field, laboratory and numerical modelling studies conducted to date indicate that gas can be extracted from gas hydrates with existing production technologies, particularly for those deposits in which the gas hydrate exists as pore-filling grains at high saturation in sand-rich reservoirs. A series of regional resource assessments indicate that substantial volumes of gas hydrate likely exist in sand-rich deposits. Recent field programs in Japan, Canada and in the United States have demonstrated the technical viability of methane extraction from gas-hydrate-bearing sand reservoirs and have investigated a range of potential production scenarios. At present, basic reservoir depressurisation shows the greatest promise and can be conducted using primarily standard industry equipment and procedures. Depressurisation is expected to be the foundation of future production systems; additional processes, such as thermal stimulation, mechanical stimulation and chemical injection, will likely also be integrated as dictated by local geological and other conditions. An innovative carbon dioxide and methane swapping technology is also being studied as a method to produce gas from select gas hydrate deposits. In addition, substantial additional volumes of gas hydrate have been found in dense arrays of grain-displacing veins and nodules in fine-grained, clay-dominated sediments; however, to date, no field tests, and very limited numerical modelling, have been conducted with regard to the production potential of such accumulations. Work remains to further refine: (1) the marine resource volumes within potential accumulations that can be

Prediction of biogas yield and its kinetics in reed canary grass using near infrared reflectance spectroscopy and chemometrics

DEFF Research Database (Denmark)

Kandel, Tanka Prasad; Gislum, René; Jørgensen, Uffe

2013-01-01

A rapid method is needed to assess biogas and methane yield potential of various kinds of substrate prior to anaerobic digestion. This study reports near infrared reflectance spectroscopy (NIRS) as a rapid alternative method to the conventional batch methods for prediction of specific biogas yield...

Is methane a new therapeutic gas?

Directory of Open Access Journals (Sweden)

Liu Wenwu

2012-09-01

Full Text Available Abstract Background Methane is an attractive fuel. Biologically, methanogens in the colon can use carbon dioxide and hydrogen to produce methane as a by-product. It was previously considered that methane is not utilized by humans. However, in a recent study, results demonstrated that methane could exert anti-inflammatory effects in a dog small intestinal ischemia-reperfusion model. Point of view Actually, the bioactivity of methane has been investigated in gastrointestinal diseases, but the exact mechanism underlying the anti-inflammatory effects is required to be further elucidated. Methane can cross the membrane and is easy to collect due to its abundance in natural gas. Although methane is flammable, saline rich in methane can be prepared for clinical use. These seem to be good news in application of methane as a therapeutic gas. Conclusion Several problems should be resolved before its wide application in clinical practice.

Direct Synthesis of Methanol by Partial Oxidation of Methane with Oxygen over Cobalt Modified Mesoporous H-ZSM-5 Catalyst

Directory of Open Access Journals (Sweden)

Yuni Krisyuningsih Krisnandi

2015-11-01

Full Text Available Partial oxidation of methane over mesoporous catalyst cobalt modified H-ZSM-5 has been carried out. Mesoporous Na-ZSM-5 (Si/Al = 35.4 was successfully synthesized using double template method which has high surface area (450 m2/g and average pore diameter distribution of 1.9 nm. The as-synthesized Na-ZSM-5 was converted to H-ZSM-5 through multi-exchange treatment with ammonium ion solution, causing decreased crystallinity and surface area, but increased porous diameter, due to dealumination during treatment process. Moreover, H-ZSM-5 was loaded with cobalt (Co = 2.5% w by the incipient impregnation method and calcined at 550 °C. Partial oxidation of methane was performed in the batch reactor with 0.75 bar methane and 2 bar of nitrogen (with impurities of 0.5% oxygen as the input at various reaction time (30, 60 and 120 min. The reaction results show that cobalt species in catalyst has an important role, because H-ZSM-5 cannot produce methanol in partial oxidation of methane. The presence of molecular oxygen increased the percentage of methanol yield. The reaction is time-dependent with the highest methanol yield (79% was acquired using Co/H-ZSM-5 catalyst for 60 min.

Creating Methane from Plastic: Recycling at a Lunar Outpost

Science.gov (United States)

Santiago-Maldonado, Edgardo; Captain, Janine; Devor, Robert; Gleaton, Jeremy

2010-01-01

The high cost of re-supply from Earth demands resources to be utilized to the fullest extent for exploration missions. The ability to refuel on the lunar surface would reduce the vehicle mass during launch and provide excess payload capability. Recycling is a key technology that maximizes the available resources by converting waste products into useful commodities. One example of this is to convert crew member waste such as plastic packaging, food scraps, and human waste into fuel. This process thermally degrades plastic in the presence of oxygen producing CO2 and CO. The CO2 and CO are then reacted with hydrogen over catalyst (Sabatier reaction) producing methane. An end-to-end laboratory-scale system has been designed and built to produce methane from plastic, in this case polyethylene. This first generation system yields 12-16% CH4 by weight of plastic used.

Biohydrogen and methane production via a two-step process using an acid pretreated native microalgae consortium.

Science.gov (United States)

Carrillo-Reyes, Julian; Buitrón, Germán

2016-12-01

A native microalgae consortium treated under thermal-acidic hydrolysis was used to produce hydrogen and methane in a two-step sequential process. Different acid concentrations were tested, generating hydrogen and methane yields of up to 45mLH 2 gVS -1 and 432mLCH 4 gVS -1 , respectively. The hydrogen production step solubilized the particulate COD (chemical oxygen demand) up to 30%, creating considerable amounts of volatile fatty acids (up to 10gCODL -1 ). It was observed that lower acid concentration presented higher hydrogen and methane production potential. The results revealed that thermal acid hydrolysis of a native microalgae consortium is a simple but effective strategy for producing hydrogen and methane in the sequential process. In addition to COD removal (50-70%), this method resulted in an energy recovery of up to 15.9kJ per g of volatile solids of microalgae biomass, one of the highest reported. Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of fat supplementation and stage of lactation on methane production in dairy cows

DEFF Research Database (Denmark)

Alstrup, Lene; Hellwing, Anne Louise Frydendahl; Lund, Peter

2015-01-01

The aim was to determine the effect of fat supplementation on methane (CH4) production and to study if the effect persists over time as lactation progresses. Rumen microbial protein synthesis and thereby milk yield may be reduced when fermentable organic matter (OM) is replaced by nonfermentable...

Boosting biogas yield of anaerobic digesters by utilizing concentrated molasses from 2nd generation bioethanol plant

Energy Technology Data Exchange (ETDEWEB)

Sarker, Shiplu [Department of Renewable Energy, Faculty of Engineering and Science, University of Agder, Grimstad-4879 (Norway); Moeller, Henrik Bjarne [Department of Biosystems Engineering, Faculty of Science and Technology, Aarhus University, Research center Foulum, Blichers Alle, Post Box 50, Tjele-8830 (Denmark)

2013-07-01

Concentrated molasses (C5 molasses) from 2nd generation bioethanol plant has been investigated for enhancing productivity of manure based digesters. A batch study at mesophilic condition (35+- 1 deg C) showed the maximum methane yield from molasses as 286 LCH4/kgVS which was approximately 63% of the calculated theoretical yield. In addition to the batch study, co-digestion of molasses with cattle manure in a semi-continuously stirred reactor at thermophilic temperature (50+- 1 deg C) was also performed with a stepwise increase in molasses concentration. The results from this experiment revealed the maximum average biogas yield of 1.89 L/L/day when 23% VSmolasses was co-digested with cattle manure. However, digesters fed with more than 32% VSmolasses and with short adaptation period resulted in VFA accumulation and reduced methane productivity indicating that when using molasses as biogas booster this level should not be exceeded.

Enteric and manure-derived methane emissions and biogas yield of slurry from dairy cows fed grass silage or maize silage with and without supplementation of rapeseed

DEFF Research Database (Denmark)

Hellwing, Anne Louise Frydendahl; Weisbjerg, Martin Riis; Møller, Henrik Bjarne

2014-01-01

was 22.5 kg/day on MS− and MS+ which was significantly higher than the 20.7 kg/day on GS−. Yield of energy corrected milk (ECM) was 2.8 and 2.5 kg higher on MS+ compared with GS− and MS−, respectively. Enteric CH4 emissions related to dry matter intake or gross energy intake were highest for GS......−. Supplementation of crushed rapeseed did not affect enteric CH4 emissions. Ultimate biogas yield and yield of CH4 in the digester were higher for MS+ and MS− than for GS−. Storage emissions from slurry increased with increasing storage temperature. The average total CH4 per kg ECM for the three treatments (mean......±standard deviation) was 25.3±2.5, 26.8±3.3 and 29.0±4.2 L CH4/kg ECM if manure was stored at 10 °C, 15 °C or 20 °C, respectively. When the slurry was digested in a laboratory scale biogas plant, the lowest total CH4 emissions per kg ECM were observed for MS+ (20.5 L CH4/ECM) and the highest for GS− (24.3 L CH4/ECM...

Determination of soil-entrapped methane

Energy Technology Data Exchange (ETDEWEB)

Alberto, M.C.R.; Neue, H.U.; Lantin, R.S.; Aduna, J.B. [Soil and Water Sciences Division, Manila (Philippines)

1996-12-31

A sampling method was developed and modified to sample soil from paddy fields for entrapped methane determination. A 25-cm long plexiglass tube (4.4-cm i.d.) fitted with gas bag was used to sample soil and entrapped gases to a depth of 15-cm. The sampling tube was shaken vigorously to release entrapped gases. Headspace gas in sampling tube and gas bag was analyzed for methane. The procedure was verified by doing field sampling weekly at an irrigated ricefield in the IRRI Research Farm on a Maahas clay soil. The modified sampling method gave higher methane concentration because it eliminated gas losses during sampling. The method gave 98% {+-} 5 recovery of soil-entrapped methane. Results of field sampling showed that the early growth stage of the rice plant, entrapped methane increased irrespective of treatment. This suggests that entrapped methane increased irrespective of treatment. This suggests that entrapped methane was primarily derived from fermentation of soil organic matter at the early growth stage. At the latter stage, the rice plant seems to be the major carbon source for methane production. 7 refs., 4 figs., 4 tabs.

Shear wall ultimate drift limits

International Nuclear Information System (INIS)

Duffey, T.A.; Goldman, A.; Farrar, C.R.

1994-04-01

Drift limits for reinforced-concrete shear walls are investigated by reviewing the open literature for appropriate experimental data. Drift values at ultimate are determined for walls with aspect ratios ranging up to a maximum of 3.53 and undergoing different types of lateral loading (cyclic static, monotonic static, and dynamic). Based on the geometry of actual nuclear power plant structures exclusive of containments and concerns regarding their response during seismic (i.e.,cyclic) loading, data are obtained from pertinent references for which the wall aspect ratio is less than or equal to approximately 1, and for which testing is cyclic in nature (typically displacement controlled). In particular, lateral deflections at ultimate load, and at points in the softening region beyond ultimate for which the load has dropped to 90, 80, 70, 60, and 50 percent of its ultimate value, are obtained and converted to drift information. The statistical nature of the data is also investigated. These data are shown to be lognormally distributed, and an analysis of variance is performed. The use of statistics to estimate Probability of Failure for a shear wall structure is illustrated

Thermodynamic and kinetic control on anaerobic oxidation of methane in marine sediments

DEFF Research Database (Denmark)

Knab, Nina J.; Dale, Andrew W.; Lettmann, Karsten

2008-01-01

The free energy yield of microbial respiration reactions in anaerobic marine sediments must be sufficient to be conserved as biologically usable energy in the form of ATP. Anaerobic oxidation of methane (AOM) coupled to sulfate reduction (SRR) has a very low standard free energy yield of ΔG  = -33...... yield was rarely less than -20 kJ mol-1 and was mostly rather constant throughout this zone. The kinetic drive was highest at the lower part of the SMTZ, matching the occurrence of maximum AOM rates. The results show that the location of maximum AOM rates is determined by a combination of thermodynamic...... and kinetic drive, whereas the rate activity mainly depends on kinetic regulation....

Methane production from marine macroalgae. A literature study with comments

Energy Technology Data Exchange (ETDEWEB)

Josefsen, K.; Aasen, I.M.

1995-06-16

This report is a survey of the published literature on fermentation of marine macroalgae to produce methane. The emphasis is placed on modern fermentation process development, including both bio-technological and economic parameters. Marine macroalgae are mostly good feedstock for methane fermentation. The main carbohydrates in seaweeds are alginate, laminaria and mannitol. Both the N and P content of kelp are usually high enough to avoid nutrient limitation. The biogass produced from marine macroalgae usually contains 50 - 65% methane. Experimentally methane yields in the order of 0.35 - 0.43 m{sup 3}/kg volatile solids (VS) have been obtained from Macrocystis pyrifera and 0.20 - 0.30 m{sup 3}/kg VS for Laminaria sp. at long retention times (50-60 days) in completely mixed reactors. The maximum reported production rate in a completely mixed reactor is 2.7 vol CH{sub 4}/reactor volume x day for M. pyrifera. In reactor configurations giving longer solids retention times (SRT) than liquid retention times (LRT), the highest reported productivity was 3.3 vol/vol x day, with loading rate 9.6 kg VS/m{sup 3} x day, HRT 10 days and SRT 23 days. There are discussions of special problems related to fermentation of marine algae, in particular the sulphur content, the toxicity of H{sub 2}S and the precipitation of heavy metals as sulphides. 72 refs., 5 figs., 13 tabs.

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.

Anaerobic co-digestion of chicken manure and microalgae Chlorella sp.: Methane potential, microbial diversity and synergistic impact evaluation.

Science.gov (United States)

Li, Ruirui; Duan, Na; Zhang, Yuanhui; Liu, Zhidan; Li, Baoming; Zhang, Dongming; Dong, Taili

2017-10-01

Anaerobic digestion (AD) is a promising alternative for livestock manure management. This paper presents the experimental results obtained through a batch experiment by using chicken manure (CM) and microalgae Chlorella sp. as co-substrates. The effect of co-digestion was evaluated by varying CM to Chlorella sp. ratios (0:10, 2:8, 4:6, 6:4, 8:2, 10: 0 based on the volatile solids (VS)). The major objective of this study is to evaluate the feasibility and synergistic impact of co-digestion of CM and Chlorella sp. Enhanced 14.20% and 76.86% methane production than CM and Chlorella sp. mono-digestion respectively was achieved in co-digestion at the ratio 8:2. In addition, the co-digestion at the ratio 8:2 showed significantly higher methane yield than the weighted average of the individual substrates' specific methane yield (WSMY), indicating strong synergy effect. The Illumina Miseq sequencing analysis showed that the AD process suppressed the acetoclastic methanogenesis Methanosaeta content; but partly enhanced hydrogenotrophic methanogenesis Methanosarcina, Methanospirillum and Methanobacterium, which was responsible for the methane production. The pre-treated microalgae was then introduced at the optimal ratio 8:2 to estimate the effect of pre-treatment of microalgae on AD process. However, the pre-treatment exhibited no positive effect. Copyright © 2017 Elsevier Ltd. All rights reserved.

Catalytic activity of mono and bimetallic Zn/Cu/MWCNTs catalysts for the thermocatalyzed conversion of methane to hydrogen

Energy Technology Data Exchange (ETDEWEB)

Erdelyi, B. [Department of Physical Chemistry, Faculty of Science, P.J. Šafárik University, Moyzesova 11, 041 54 Košice (Slovakia); Institute of Physics, Faculty of Science, P.J. Šafárik University, Park Angelium 9, 040 01 Košice (Slovakia); Oriňak, A., E-mail: andrej.orinak@upjs.sk [Department of Physical Chemistry, Faculty of Science, P.J. Šafárik University, Moyzesova 11, 041 54 Košice (Slovakia); Oriňaková, R. [Department of Physical Chemistry, Faculty of Science, P.J. Šafárik University, Moyzesova 11, 041 54 Košice (Slovakia); Lorinčík, J. [Research Center Rez, Hlavní 130, 250 68 Husinec-Řež (Czech Republic); Jerigová, M. [Department of Physical Chemistry, Comenius University, Mlynská dolina 842 15 Bratislava 4 (Slovakia); Velič, D. [Department of Physical Chemistry, Comenius University, Mlynská dolina 842 15 Bratislava 4 (Slovakia); International Laser Centre, Ilkovičová 3, 841 01 Bratislava (Slovakia); Mičušík, M. [Polymer institute, Slovak Academy of Sciences, Dubravská cesta 9, 84541 Bratislava (Slovakia); and others

2017-02-28

Highlights: • Zn/Cu/MWCNTs catalyst with good activity. • Methane conversion to hydrogen with high effectivity. • ZnO/Cu responsible for catalytic activity. - Abstract: Mono and bimetallic multiwalled carbon nanotubes (MWCNTs) fortified with Cu and Zn metal particles were studied to improve the efficiency of the thermocatalytic conversion of methane to hydrogen. The surface of the catalyst and the dispersion of the metal particles were studied by scanning electron microscopy (SEM), secondary ion mass spectrometry (SIMS) and with energy-dispersive X-ray spectroscopy (EDS). It was confirmed that the metal particles were successfully dispersed on the MWCNT surface and XPS analysis showed that the Zn was oxidised to ZnO at high temperatures. The conversion of methane to hydrogen during the catalytic pyrolysis was studied by pyrolysis gas chromatography using different amounts of catalyst. The best yields of hydrogen were obtained using pyrolysis conditions of 900 °C and 1.2 mg of Zn/Cu/MWCNT catalyst for 1.5 mL of methane.The initial conversion of methane to hydrogen obtained with Zn/Cu/MWCNTs was 49%, which represent a good conversion rate of methane to hydrogen for a non-noble metal catalyst.

Ultimate and proximate explanations of strong reciprocity.

Science.gov (United States)

Vromen, Jack

2017-08-23

Strong reciprocity (SR) has recently been subject to heated debate. In this debate, the "West camp" (West et al. in Evol Hum Behav 32(4):231-262, 2011), which is critical of the case for SR, and the "Laland camp" (Laland et al. in Science, 334(6062):1512-1516, 2011, Biol Philos 28(5):719-745, 2013), which is sympathetic to the case of SR, seem to take diametrically opposed positions. The West camp criticizes advocates of SR for conflating proximate and ultimate causation. SR is said to be a proximate mechanism that is put forward by its advocates as an ultimate explanation of human cooperation. The West camp thus accuses advocates of SR for not heeding Mayr's original distinction between ultimate and proximate causation. The Laland camp praises advocates of SR for revising Mayr's distinction. Advocates of SR are said to replace Mayr's uni-directional view on the relation between ultimate and proximate causes by the bi-directional one of reciprocal causation. The paper argues that both the West camp and the Laland camp misrepresent what advocates of SR are up to. The West camp is right that SR is a proximate cause of human cooperation. But rather than putting forward SR as an ultimate explanation, as the West camp argues, advocates of SR believe that SR itself is in need of ultimate explanation. Advocates of SR tend to take gene-culture co-evolutionary theory as the correct meta-theoretical framework for advancing ultimate explanations of SR. Appearances notwithstanding, gene-culture coevolutionary theory does not imply Laland et al.'s notion of reciprocal causation. "Reciprocal causation" suggests that proximate and ultimate causes interact simultaneously, while advocates of SR assume that they interact sequentially. I end by arguing that the best way to understand the debate is by disambiguating Mayr's ultimate-proximate distinction. I propose to reserve "ultimate" and "proximate" for different sorts of explanations, and to use other terms for distinguishing

Physical demands in competitive ultimate frisbee

DEFF Research Database (Denmark)

Krustrup, Peter; Mohr, Magni

2015-01-01

The objective was to study game demands in competitive ultimate Frisbee by performing match analysis during a game. Thirteen moderately trained (Yo-Yo intermittent recovery test levels 1 and 2 [Yo-Yo IR1 and IR2] performance: 1790 ± 382 m and 657 ± 225 m, respectively) competitive male ultimate...... = 0.74, p ≤ 0.05). Ultimate Frisbee is an intense intermittent team sport with high cardiovascular loading and clear indications of fatigue toward the end of each half. Yo-Yo IR test performances correlate with physical match performance....

Nonlinear finite element analysis of nuclear reinforced prestressed concrete containments up to ultimate load capacity

International Nuclear Information System (INIS)

Gupta, A.; Singh, R.K.; Kushwaha, H.S.; Mahajan, S.C.; Kakodkar, A.

1996-01-01

For safety evaluation of nuclear structures a finite element code ULCA (Ultimate Load Capacity Assessment) has been developed. Eight/nine noded isoparametric quadrilateral plate/shell element with reinforcement as a through thickness discrete but integral smeared layer of the element is presented to analyze reinforced and prestressed concrete structures. Various constitutive models such as crushing, cracking in tension, tension stiffening and rebar yielding are studied and effect of these parameters on the reserve strength of structures is brought out through a number of benchmark tests. A global model is used to analyze the prestressed concrete containment wall of a typical 220 MWe Pressurized Heavy Water Reactor (PHWR) up to its ultimate capacity. This demonstrates the adequacy of Indian PHWR containment design to withstand severe accident loads

Experimental evaluation of methane dry reforming process on a membrane reactor to hydrogen production

Energy Technology Data Exchange (ETDEWEB)

Silva, Fabiano S.A.; Benachour, Mohand; Abreu, Cesar A.M. [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil). Dept. of Chemical Engineering], Email: f.aruda@yahoo.com.br

2010-07-01

In a fixed bed membrane reactor evaluations of methane-carbon dioxide reforming over a Ni/{gamma}- Al{sub 2}O{sub 3} catalyst were performed at 773 K, 823 K and 873 K. A to convert natural gas into syngas a fixed-bed reactor associate with a selective membrane was employed, where the operating procedures allowed to shift the chemical equilibrium of the reaction in the direction of the products of the process. Operations under hydrogen permeation, at 873 K, promoted the increase of methane conversion, circa 83%, and doubled the yield of hydrogen production, when compared with operations where no hydrogen permeation occurred. (author)

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)

Wood to Bio-Methane demonstration project in the Netherlands

Energy Technology Data Exchange (ETDEWEB)

Van der Meijden, C.M.; Van der Drift, A.; Rietveld, G. [ECN Biomass and Energy Efficiency, Petten (Netherlands); Koenemann, J.W. [Dahlman Renewable Technology, P.O. Box 438, 3140 AK Maassluis (Netherlands); Sierhuis, W. [HVCgroup, P.O. Box 9199, 1800 GD, Alkmaar (Netherlands)

2013-06-15

The Energy research Centre of the Netherlands (ECN) has developed a biomass gasification technology, called the MILENA technology. The Milena gasification technology has a high cold gas efficiency and high methane yield, making it very suitable for gas engine and turbine applications as well as upgrading of the gas into Bio-Methane. An overall efficiency from biomass to power of over 30% is possible, whereas 70% efficiency is achievable from biomass to gas grid quality methane. HVC Group (situated in Alkmaar, North Holland) is a modern public service waste company. HVC converts waste streams which cannot be recycled into usable forms of energy. HVC has a 75 MWth waste wood boiler in operation which produces heat and electricity, and an anaerobic digester which converts domestic fruit, vegetable and garden waste into Bio-Methane. HVC expects an important role for Bio-Methane in the future and HVC has decided to join ECN with the development, demonstration and implementation of the MILENA Bio-Methane technology. Linked to the Bio-Methane demonstration project is the Netherlands Expertise Centre for Biomass Gasification. The MILENA demonstration project and the Gasification Expert Centre are supported by the following companies and organizations: HVC, TAQA, Gasunie, Dahlman, province of North Holland, the Alkmaar municipality and ECN. In 2010 and 2012 extensive lab-scale and pilot scale tests have been executed by ECN and HVC to proof that the gasification and gas cleaning technology is ready for commercial application. The final step in this test program was a duration test in the 800 kWth MILENA pilot plant coupled to the OLGA tar removal unit. The goal was to show high availability. The result of the test was an availability of the gasifier of 96% and an overall availability (including gas cooling and gas cleaning) of 85%. The results of the duration tests convinced HVC and the other partners that the technology is ready for scale-up. The results produced in the

Methane fermentation and kinetics of wheat straw pretreated substrates co-digested with cattle manure in batch assay

International Nuclear Information System (INIS)

Krishania, M.; Vijay, V.K.; Chandra, R.

2013-01-01

Lignocellulosic biomass contains high percentages of lignin, which is hard to biodegrade and therefore, pretreatment is required to enhance energy recovery yield. In this study, five types of pretreatments, i.e., dilute acid, alkali, acid–alkali combination and calcium hydroxide–sodium carbonate combination, and grinding were applied on wheat straw to enhance the efficiency of methane fermentation. Methane fermentation of untreated and pretreated substrates was evaluated at 35 °C temperature in 5 L glass bottle reactors. Cumulative CH 4 yields of these pretreated substrates were found as 0.125 ± 0.002, 0.370 ± 0.02, 0.003 ± 0.005, 0.380 ± 0.017 and 0.241 ± 0.005 m 3 /kg of VS (volatile solids), respectively for, T1, T2, T3, T4 and T5 treatments compared to that of untreated treatment T0 as 0.191 ± 0.004 m 3 /kg of VS. Alkali (2% NaOH on weight/volume ratio basis) and calcium hydroxide–sodium carbonate combination (3% Ca(OH) 2 + 3% Na 2 CO 3 on weight/volume ratio basis) pretreatments have been found to improve biogas and CH 4 production yields by 94.0% and 99.0%, respectively, in comparison to the untreated wheat straw substrate. Gompertz model used to analyze the kinetic behavior of anaerobic digestion process in present study. Kinetic study indicates that Gompertz equation best describe the cumulative gas production as a function of the digestion time. - Highlights: • H 2 SO 4 , NaOH, H 2 SO 4 + NaOH, Ca(OH) 2 + Na 2 CO 3 , grinding pretreatments were studied on wheat straw. • Wheat straw co-digestion with cattle manure in 40:60 ratio provided maximum methane yield. • 2% NaOH pretreated substrate found to increase biogas and CH 4 production yields by 94.0%. • 3% Ca(OH) 2 + 3% Na 2 CO 3 pretreatment found to improve biogas and CH 4 production yields by 99.0%

Photocatalytic conversion of methane to methanol

Energy Technology Data Exchange (ETDEWEB)

Taylor, C.E.; Noceti, R.P.; D`Este, J.R. [Pittsburgh Energy Technology Center, PA (United States)

1995-12-31

A long-term goal of our research group is the exploration of novel pathways for the direct oxidation of methane to liquid fuels, chemicals, and intermediates. The use of three relatively abundant and inexpensive reactants, light, water, and methane, to produce methanol is attractive. The products of reaction, methanol and hydrogen, are both commercially desirable, methanol being used as is or converted to a variety of other chemicals, and the hydrogen could be utilized in petroleum and/or chemical manufacturing. Methane is produced as a by-product of coal gasification. Depending upon reactor design and operating conditions, up to 18% of total gasifier product may be methane. In addition, there are vast proven reserves of geologic methane in the world. Unfortunately, a large fraction of these reserves are in regions where there is little local demand for methane and it is not economically feasible to transport it to a market. There is a global research effort under way in academia, industry, and government to find methods to convert methane to useful, more readily transportable and storable materials. Methanol, the initial product of methane oxidation, is a desirable product of conversion because it retains much of the original energy of the methane while satisfying transportation and storage requirements. Investigation of direct conversion of methane to transportation fuels has been an ongoing effort at PETC for over 10 years. One of the current areas of research is the conversion of methane to methanol, under mild conditions, using light, water, and a semiconductor photocatalyst. The use of three relatively abundant and inexpensive reactants, light, water, and methane, to produce methanol, is attractive. Research in the laboratory is directed toward applying the techniques developed for the photocatalytic splitting of the water and the photochemical conversion of methane.

Need for a marginal methodology in assessing natural gas system methane emissions in response to incremental consumption.

Science.gov (United States)

Mac Kinnon, Michael; Heydarzadeh, Zahra; Doan, Quy; Ngo, Cuong; Reed, Jeff; Brouwer, Jacob

2018-05-17

Accurate quantification of methane emissions from the natural gas system is important for establishing greenhouse gas inventories and understanding cause and effect for reducing emissions. Current carbon intensity methods generally assume methane emissions are proportional to gas throughput so that increases in gas consumption yield linear increases in emitted methane. However, emissions sources are diverse and many are not proportional to throughput. Insights into the causal drivers of system methane emissions, and how system-wide changes affect such drivers are required. The development of a novel cause-based methodology to assess marginal methane emissions per unit of fuel consumed is introduced. The carbon intensities of technologies consuming natural gas are critical metrics currently used in policy decisions for reaching environmental goals. For example, the low-carbon fuel standard in California uses carbon intensity to determine incentives provided. Current methods generally assume methane emissions from the natural gas system are completely proportional to throughput. The proposed cause-based marginal emissions method will provide a better understanding of the actual drivers of emissions to support development of more effective mitigation measures. Additionally, increasing the accuracy of carbon intensity calculations supports the development of policies that can maximize the environmental benefits of alternative fuels, including reducing greenhouse gas emissions.

Reducing Open Cell Landfill Methane Emissions with a Bioactive Alternative Daily

Energy Technology Data Exchange (ETDEWEB)

Helene Hilger; James Oliver; Jean Bogner; David Jones

2009-03-31

made but prone to rapid desiccation. Bacterial adsorption onto foam padding, natural sponge, and geotextile was successful. The most important factor for success appeared to be water holding capacity. Prototype biotarps made with geotextiles plus adsorbed methane oxidizing bacteria were tested for their responses to temperature, intermittent starvation, and washing (to simulate rainfall). The prototypes were mesophilic, and methane oxidation activity remained strong after one cycle of starvation but then declined with repeated cycles. Many of the cells detached with vigorous washing, but at least 30% appeared resistant to sloughing. While laboratory landfill simulations showed that four-layer composite biotarps made with two different types of geotextile could remove up to 50% of influent methane introduced at a flux rate of 22 g m{sup -2} d{sup -1}, field experiments did not yield high activity levels. Tests revealed that there were high hour-to-hour flux variations in the field, which, together with frequent rainfall events, confounded the field testing. Overall, the findings suggest that a methanotroph embedded biotarp appears to be a feasible strategy to mitigate methane emission from landfill cells, although the performance of field-tested biotarps was not robust here. Tarps will likely be best suited for spring and summer use, although the methane oxidizer population may be able to shift and adapt to lower temperatures. The starvation cycling of the tarp may require the capacity for intermittent reinoculation of the cells, although it is also possible that a subpopulation will adapt to the cycling and become dominant. Rainfall is not expected to be a major factor, because a baseline biofilm will be present to repopulate the tarp. If strong performance can be achieved and documented, the biotarp concept could be extended to include interception of other compounds beyond methane, such as volatile aromatic hydrocarbons and chlorinated solvents.

Methane clathrates in the solar system.

Science.gov (United States)

Mousis, Olivier; Chassefière, Eric; Holm, Nils G; Bouquet, Alexis; Waite, Jack Hunter; Geppert, Wolf Dietrich; Picaud, Sylvain; Aikawa, Yuri; Ali-Dib, Mohamad; Charlou, Jean-Luc; Rousselot, Philippe

2015-04-01

We review the reservoirs of methane clathrates that may exist in the different bodies of the Solar System. Methane was formed in the interstellar medium prior to having been embedded in the protosolar nebula gas phase. This molecule was subsequently trapped in clathrates that formed from crystalline water ice during the cooling of the disk and incorporated in this form into the building blocks of comets, icy bodies, and giant planets. Methane clathrates may play an important role in the evolution of planetary atmospheres. On Earth, the production of methane in clathrates is essentially biological, and these compounds are mostly found in permafrost regions or in the sediments of continental shelves. On Mars, methane would more likely derive from hydrothermal reactions with olivine-rich material. If they do exist, martian methane clathrates would be stable only at depth in the cryosphere and sporadically release some methane into the atmosphere via mechanisms that remain to be determined. In the case of Titan, most of its methane probably originates from the protosolar nebula, where it would have been trapped in the clathrates agglomerated by the satellite's building blocks. Methane clathrates are still believed to play an important role in the present state of Titan. Their presence is invoked in the satellite's subsurface as a means of replenishing its atmosphere with methane via outgassing episodes. The internal oceans of Enceladus and Europa also provide appropriate thermodynamic conditions that allow formation of methane clathrates. In turn, these clathrates might influence the composition of these liquid reservoirs. Finally, comets and Kuiper Belt Objects might have formed from the agglomeration of clathrates and pure ices in the nebula. The methane observed in comets would then result from the destabilization of clathrate layers in the nuclei concurrent with their approach to perihelion. Thermodynamic equilibrium calculations show that methane-rich clathrate

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...

Situation of methanization installations in Haute-Normandie. Phase 2: Assessment of the regional sector. Phase 3: Development perspectives for the methanization sector in Haute-Normandie. To understand methanization. Haute-Normandie Commission of expertise on methanization

International Nuclear Information System (INIS)

Convert, Mathilde

2012-10-01

A first report proposes an analysis of the situation of methanization installations in the Haute-Normandie region while recalling the national context. It briefly reports an analysis and assessment of waste flows, processed effluents, by-products and biomass displaying an energetic potential. It describes methanization installations by addressing the different steps of the methanization process, by presenting the different digestion indicators, by briefly evoking the issue of the return-to-soil of digestates, and by presenting various operational data. Financial aspects are then addressed (investments and subsidies, financial balance of farm-based and collective installations), and an overview of methanization projects in the region and development perspectives is proposed. The second report more precisely analyses development perspectives for the methanization sector in the region through a brief assessment of the methanizable organic substrate resource, a discussion of different associated challenges (energy, agronomic, environmental and societal), a discussion of development levers and brakes, and an analysis of competitions (related to the use of industrial by-products, between processing installations, and related to agricultural soils). Another document proposes an overview of various aspects of methanization: a tool for territorial development, regulatory framework, evolution of installations in the region, assets of methanization, and role of the regional commission of expertise on methanization

Methanization in Burgundy-Franche-Comte - Figures and benchmarks. Agricultural methanization in Franche-Comte - Reflection guide for projects. Methanization development in Burgundy - Assessment 2014. Biogas sector in Burgundy. Methanization development in Burgundy - How to develop a project in Burgundy

International Nuclear Information System (INIS)

Aucordonnier, Bertrand; SIBUE, Lionel; Granger, Sylvie; Pervenchon, Frank; Forgue, Isabelle; Lirzin, Frank; Aucordonnier, Bertand; Abrahamse, Philippe; Dondaine, Regis; Rousseau, Christophe; Fevre, Jean-Michel; Carbonnier, Arnaud; Gontier, Thomas; Lemaire, Sylvie; Gallois, Vincent; Lachaize, M.

2015-03-01

A first document proposes graphs, figures and maps which illustrate various aspects of the situation and development of methanization in France and in the Burgundy-Franche-Comte region (number and location of installations, production evolution, biomass origins, biogas valorisation). A second document presents methanization (basic principles, process types, valorisation), describes agricultural methanization (substrate origin, use of final energy, use of digestates) and proposes elements of thought for methanization development regarding waste origin, project definition, various concerns (energy, environment, agriculture), digestate use and quantities, methane use, and installation sizing. A publication then proposes a synthetic overview of methanization development in Burgundy: number of supported projects, installations (evolution of their number, used materials, production), and support activities. The next publication proposes an assessment and an overview of the biogas sector in Burgundy: presentation and recommendations, assessment in terms of jobs, activities and expertise, professional education and training. The last document recalls some elements related to the methanization technique, outlines some important issues (materials, valorisation type for biogas and for digestate) to be addressed for an agricultural methanization project, and evokes benefits of methanization and some economic aspects. It also briefly describes how to start a project in the region

Modeling of methane bubbles released from large sea-floor area: Condition required for methane emission to the atmosphere

OpenAIRE

Yamamoto, A.; Yamanaka, Y.; Tajika, E.

2009-01-01

Massive methane release from sea-floor sediments due to decomposition of methane hydrate, and thermal decomposition of organic matter by volcanic outgassing, is a potential contributor to global warming. However, the degree of global warming has not been estimated due to uncertainty over the proportion of methane flux from the sea-floor to reach the atmosphere. Massive methane release from a large sea-floor area would result in methane-saturated seawater, thus some methane would reach the atm...

Methane Emission and Milk Production of Dairy Cows Grazing Pastures Rich in Legumes or Rich in Grasses in Uruguay.

Science.gov (United States)

Dini, Yoana; Gere, José; Briano, Carolina; Manetti, Martin; Juliarena, Paula; Picasso, Valentin; Gratton, Roberto; Astigarraga, Laura

2012-06-08

Understanding the impact of changing pasture composition on reducing emissions of GHGs in dairy grazing systems is an important issue to mitigate climate change. The aim of this study was to estimate daily CH₄ emissions of dairy cows grazing two mixed pastures with contrasting composition of grasses and legumes: L pasture with 60% legumes on Dry Matter (DM) basis and G pasture with 75% grasses on DM basis. Milk production and CH₄ emissions were compared over two periods of two weeks during spring using eight lactating Holstein cows in a 2 × 2 Latin square design. Herbage organic matter intake (HOMI) was estimated by chromic oxide dilution and herbage organic matter digestibility (OMD) was estimated by faecal index. Methane emission was estimated by using the sulfur hexafluoride (SF6) tracer technique adapted to collect breath samples over 5-day periods. OMD (0.71) and HOMI (15.7 kg OM) were not affected by pasture composition. Milk production (20.3 kg/d), milk fat yield (742 g/d) and milk protein yield (667 g/d) were similar for both pastures. This may be explained by the high herbage allowance (30 kg DM above 5 cm/cow) which allowed the cows to graze selectively, in particular in grass sward. Similarly, methane emission expressed as absolute value (368 g/d or 516 L/d) or expressed as methane yield (6.6% of Gross Energy Intake (GEI)) was not affected by treatments. In conclusion, at high herbage allowance, the quality of the diet selected by grazing cows did not differ between pastures rich in legumes or rich in grasses, and therefore there was no effect on milk or methane production.

Source Attribution of Methane Emissions in Northeastern Colorado Using Ammonia to Methane Emission Ratios

Science.gov (United States)

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

2015-12-01

Due to recent advances in extraction technology, oil and natural gas extraction and processing in the Denver-Julesburg basin has increased substantially in the past decade. Northeastern Colorado is also home to over 250 concentrated animal feeding operations (CAFOs), capable of hosting over 2 million head of ruminant livestock (cattle and sheep). Because of methane's high Global Warming Potential, quantification and attribution of methane emissions from oil and gas development and agricultural activity are important for guiding greenhouse gas emission policy. However, due to the co-location of these different sources, top-down measurements of methane are often unable to attribute emissions to a specific source or sector. In this work, we evaluate the ammonia:methane emission ratio directly downwind of CAFOs using a mobile laboratory. Several CAFOs were chosen for periodic study over a 12-month period to identify diurnal and seasonal variation in the emission ratio as well as differences due to livestock type. Using this knowledge of the agricultural ammonia:methane emission ratio, aircraft measurements of ammonia and methane over oil and gas basins in the western US during the Shale Oil and Natural Gas Nexus (SONGNEX) field campaign in March and April 2015 can be used for source attribution of methane emissions.

Modified batch anaerobic digestion assay for testing efficiencies of trace metal additives to enhance methane production of energy crops.

Science.gov (United States)

Brulé, Mathieu; Bolduan, Rainer; Seidelt, Stephan; Schlagermann, Pascal; Bott, Armin

2013-01-01

Batch biochemical methane potential (BMP) assays to evaluate the methane yield of biogas substrates such as energy crops are usually carried out with undiluted inoculum. A BMP assay was performed on two energy crops (green cuttings and grass silage). Anaerobic digestion was performed both with and without supplementation of three commercial additives containing trace metals in liquid, solid or adsorbed form (on clay particles). In order to reveal positive effects of trace metal supplementation on the methane yield, besides undiluted inoculum, 3-fold and 10-fold dilutions of the inoculum were applied for substrate digestion. Diluted inoculum variants were supplemented with both mineral nutrients and pH-buffering substances to prevent a collapse of the digestion process. As expected, commercial additives had no effect on the digestion process performed with undiluted inoculum, while significant increases of methane production through trace element supplementation could be observed on the diluted variants. The effect of inoculum dilution may be twofold: (1) decrease in trace metal supplementation from the inoculum and (2) reduction in the initial number of bacterial cells. Bacteria require higher growth rates for substrate degradation and hence have higher trace element consumption. According to common knowledge of the biogas process, periods with volatile fatty acids accumulation and decreased pH may have occurred in the course ofanaerobic digestion. These effects may have led to inhibition, not only ofmethanogenes and acetogenes involved in the final phases of methane production, but also offibre-degrading bacterial strains involved in polymer hydrolysis. Further research is required to confirm this hypothesis.

Green chemistry perspectives of methane conversion via oxidative methylation of aromatics over zeolite catalysts

Energy Technology Data Exchange (ETDEWEB)

Adebajo, M.O. [University of Queensland, St Lucia, Qld. (Australia)

2007-06-15

This paper provides a general overview of the recent work that we and other researchers have done on the utilisation of methane for catalytic methylation of aromatic compounds and for direct coal liquefaction for the production of liquid hydrocarbons. In particular, the paper presents a detailed description of more recent substantial experimental evidence that we have provided for the requirement of oxygen as a stoichiometry reactant for benzene methylation with methane over moderately acidic zeolite catalysts. The reaction, which has been termed 'oxidative methylation', was thus postulated to involve a two-step mechanism involving intermediate methanol formation by methane partial oxidation, followed by benzene methylation with methanol in the second step. However, strongly acidic zeolites can cause cracking of benzene to yield methylated products in the absence of oxygen. The participation of methane and oxygen, and the effective use of zeolite catalysts in this methylation reaction definitely have some positive green chemistry implications. Thus, the results of these previous studies are also discussed in this review in light of the principles and tools of green chemistry. Various metrics were used to evaluate the greenness, cost-effectiveness, and material and energy efficiency of the oxidative methylation reaction.

Linseed plus nitrate in the diet for fattening bulls: effects on methane emission, animal health and residues in offal.

Science.gov (United States)

Doreau, M; Arbre, M; Popova, M; Rochette, Y; Martin, C

2018-03-01

The combination of linseed and nitrate is known to decrease enteric methane emission in dairy cows but few studies have been carried out in fattening cattle for animal liveweight gain, enteric methane emission, animal health and presence of residues in beef products. To address this gap, 16 young bulls received a control (C) diet between weaning at 9 months and 14 months, then were split into two groups of eight balanced on feed intake, BW gain and methane emission to receive either the C diet or a diet moderately supplemented with extruded linseed and calcium nitrate (LN) for 2 months before being slaughtered. On a dry matter (DM) basis, the C diet contained 70% baled grass silage and 30% concentrate mainly made of maize, wheat and rapeseed meal. In the LN diet, rapeseed meal and a fraction of cereals were replaced by 35% extruded linseed and 6% calcium nitrate; linseed fatty acids and nitrate supply in the LN diet were 1.9% and 1.0%, respectively. Methane emission was measured continuously using the GreenFeed system. Methaemoglobin was determined every week in peripheral blood from bulls receiving the LN diet. Nitrate and nitrite concentrations were determined in rumen, liver and tongue sampled at slaughter. Dry matter intake tended to be lower for LN diet (P=0.10). Body weight gain was lower for LN diet (P=0.01; 1.60 and 1.26 kg/day for C and LN diet, respectively). Daily methane emission was 9% lower (Pmethane yield did not differ between diets (24.1 and 23.2 g/kg DM intake for C and LN diet, respectively, P=0.34). Methaemoglobin was under the limit of detection (methane yield and impaired bull liveweight gain but without adverse effects for animal health and food safety.

Methane emissions from natural wetlands

Energy Technology Data Exchange (ETDEWEB)

Meyer, J.L. [Georgia Univ., Athens, GA (United States); Burke, R.A. Jr. [Environmental Protection Agency, Athens, GA (United States). Environmental Research Lab.

1993-09-01

Analyses of air trapped in polar ice cores in conjunction with recent atmospheric measurements, indicate that the atmospheric methane concentration increased by about 250% during the past two or three hundred years (Rasmussen and Khalil, 1984). Because methane is a potent ``greenhouse`` gas, the increasing concentrations are expected to contribute to global warning (Dickinson and Cicerone, 1986). The timing of the methane increase suggests that it is related to the rapid growth of the human population and associated industrialization and agricultural development. The specific causes of the atmospheric methane concentration increase are not well known, but may relate to either increases in methane sources, decreases in the strengths of the sinks, or both.

Cryptic Methane Emissions from Upland Forest Ecosystems

Energy Technology Data Exchange (ETDEWEB)

Megonigal, Patrick [Smithsonian Institution, Washington, DC (United States); Pitz, Scott [Johns Hopkins Univ., Baltimore, MD (United States); Smithsonian Institution, Washington, DC (United States)

2016-04-19

This exploratory research on Cryptic Methane Emissions from Upland Forest Ecosystems was motivated by evidence that upland ecosystems emit 36% as much methane to the atmosphere as global wetlands, yet we knew almost nothing about this source. The long-term objective was to refine Earth system models by quantifying methane emissions from upland forests, and elucidate the biogeochemical processes that govern upland methane emissions. The immediate objectives of the grant were to: (i) test the emerging paradigm that upland trees unexpectedly transpire methane, (ii) test the basic biogeochemical assumptions of an existing global model of upland methane emissions, and (iii) develop the suite of biogeochemical approaches that will be needed to advance research on upland methane emissions. We instrumented a temperate forest system in order to explore the processes that govern upland methane emissions. We demonstrated that methane is emitted from the stems of dominant tree species in temperate upland forests. Tree emissions occurred throughout the growing season, while soils adjacent to the trees consumed methane simultaneously, challenging the concept that forests are uniform sinks of methane. High frequency measurements revealed diurnal cycling in the rate of methane emissions, pointing to soils as the methane source and transpiration as the most likely pathway for methane transport. We propose the forests are smaller methane sinks than previously estimated due to stem emissions. Stem emissions may be particularly important in upland tropical forests characterized by high rainfall and transpiration, resolving differences between models and measurements. The methods we used can be effectively implemented in order to determine if the phenomenon is widespread.

Two-phase anaerobic digestion of mixed waste streams to separate generation of bio-hydrogen and bio-methane

Energy Technology Data Exchange (ETDEWEB)

Siddiqui, Z.; Horam, N.J. [Leeds Univ. (United Kingdom). School of Civil Engineering

2010-07-01

The purpose of this study was to investigate the net energy potential of single stage mesophilic reactor and two phase mesophilic reactor (hydrogeniser followed by methaniser) using the mix of process industrial food waste (IFW) and sewage sludge (SS). Two-phase reactor efficiency was analysed based on individual optimum influent/environmental (C:N and pH) and reactor/engineering (HRT and OLR) conditions achieved using the batch and continuous reactor study for the hydrogen and methane. Optimum C:N 20 and pH 5.5{+-}0.5 was observed using the Bio-H{sub 2} potential (BHP) and C:N 15 and pH 6.5{+-}0.3 for the biochemical methane potential (BMP) test. The maximum hydrogen content of 47% (v/v) was achieved using OLR 6 g VS/L/d and HRT of 5 days. Increase in hydrogen yield was noticed with consistent decrease in OLR. The volatile solids (VS) removal and hydrogen yield was observed in range 41.3 to 47% and 112.3 to 146.7 mL/ gVS{sub removed}. The specific hydrogen production rate improved at low OLR, 0.2 to 0.4 L/(L.d) using OLR 7.1 and 6 g VS/L/d respectively was well corroborated comparable to previous reported results at OLR 6 gVS/L/d using the enriched carbohydrate waste stream in particular to food wastes. A significant increase in VFA concentrations were noticed shifting OLR higher from 6 g VS/L/d thereby unbalancing the reactor pH and the biogas yield respectively. In similar, maximum methane content of 70% (v/v) was achieved using OLR of 3.3 gVS/L/d and HRT of 10 days. Slight decrease in methane content was noticed thereby increasing HRT to 12 and 15 days respectively. The volatile solids (VS) removal and specific methane production rate was observed in range 57.6 to 68.7 and 0.22 to 1.19 L/(L.d). The specific methane production potential improved thereby reducing the HRT and optimum yield was recorded as 476.6 mL/gVS{sub removed} using OLR 3.3 gVS/L/d. The energy potential of optimum condition in single stage hydorgeniser is 2.27 MW/tonne VS{sub fed}. Using the

Rapid, Real-time Methane Detection in Ground Water Using a New Gas-Water Equilibrator Design

Science.gov (United States)

Ruybal, C. J.; DiGiulio, D. C.; Wilkin, R. T.; Hargrove, K. D.; McCray, J. E.

2014-12-01

Recent increases in unconventional gas development have been accompanied by public concern for methane contamination in drinking water wells near production areas. Although not a regulated pollutant, methane may be a marker contaminant for others that are less mobile in groundwater and thus may be detected later, or at a location closer to the source. In addition, methane poses an explosion hazard if exsolved concentrations reach 5 - 15% volume in air. Methods for determining dissolved gases, such as methane, have evolved over 60 years. However, the response time of these methods is insufficient to monitor trends in methane concentration in real-time. To enable rapid, real-time monitoring of aqueous methane concentrations during ground water purging, a new gas-water equilibrator (GWE) was designed that increases gas-water mass exchange rates of methane for measurement. Monitoring of concentration trends allows a comparison of temporal trends between sampling events and comparison of baseline conditions with potential post-impact conditions. These trends may be a result of removal of stored casing water, pre-purge ambient borehole flow, formation physical and chemical heterogeneity, or flow outside of well casing due to inadequate seals. Real-time information in the field can help focus an investigation, aid in determining when to collect a sample, save money by limiting costs (e.g. analytical, sample transport and storage), and provide an immediate assessment of local methane concentrations. Four domestic water wells, one municipal water well, and one agricultural water well were sampled for traditional laboratory analysis and compared to the field GWE results. Aqueous concentrations measured on the GWE ranged from non-detect to 1,470 μg/L methane. Some trends in aqueous methane concentrations measured on the GWE were observed during purging. Applying a paired t-test comparing the new GWE method and traditional laboratory analysis yielded a p-value 0

Methane Group Ions in Saturn’s Outer Magnetosphere?

Science.gov (United States)

Sittler, E. C.; Hartle, R. E.; Cooper, J. F.; Johnson, R. E.; Smith, H.; Shappirio, M.; Reisenfeld, D. B.

2009-12-01

Yelle et al. [2008] have estimated from Cassini Ion Neutral Mass Spectrometer (INMS) measurements that methane is escaping from Titan’s upper atmosphere at the rate of 2.5-3.0×109 mol/cm2/s and in order to explain this loss rate Strobel [2008] has proposed a hydrodynamic escape model to explain such high loss rates. This translates to loss of 2.8×1027 methane mol/s. The consequence of this work is the formation of a methane torus around Saturn which will dissociate to CH3 and other fragments of methane. The CH3 will then become ionized to form CH3+ with pickup energies ≈ keV after which it can be detected by the Cassini Plasma Spectrometer (CAPS) Ion Mass Spectrometer (IMS). Up till now the ion composition within Saturn’s outer magnetosphere in the vicinity of Titan’s orbit have yielded negative results with water group ions W+ dominating. The water group ions probably result from the emission of fast neutrals from the Enceladus torus via charge exchange reactions but still gravitationally bound to Saturn [see Johnson et al., 2005 and Sittler et al. 2006] and then become ionized in the outer magnetosphere as ~≈keV pickup ions. The CAPS IMS produces two ion composition data products, one called Straight Through (ST) and the other Linear Electric Field (LEF). The first has a higher sensitivity, while the latter has a greater discrimination in time-of-flight (TOF). For ST data O+ and CH4+ have similar TOF with the primary discriminator being the O- fragment which appears at a different TOF than for mass 16 ions. One can also look for other discriminators called ghost peaks. In case of LEF W+ ions produce TOF peak close to that for atomic O+ and the methane will produce TOF close to that for atomic C+ which has a significantly different(shorter) TOF than O+. We will be reporting on our continual search for methane ions within Saturn’s outer magnetosphere. References: 1. Yelle, R. V., J. Cui and I.C.F. Müller-Wodarg, JGR, 2008. 2. Strobel, D. F., Icarus

Challenges related to methanization - Bibliographical synthesis by France Nature Environnement. Opinion of FNE on methanization: Which challenges and which desirable development? Methascope: assessment support tool for a methanization project

International Nuclear Information System (INIS)

Desaunay, Thomas; Mathien, Adeline; Dorioz, Camille; Saint-Aubin, Thibaud; Banaszuk, Agnes; Badereau, Benedicte de; Capiez, Nathalie; Zoffoli, Maxime

2014-12-01

A first document proposes a bibliographical synthesis on the various challenges related to methanization. It addresses the following issues: biogas and public policies, methanization as a natural process of transformation of organic matter, different installations for different territories, matters which can be used in methanization, biogas as a renewable and local energy which can be transformed according to needs, properties and uses of digestate, choice between composting and methanization, energetic crops, methanization and nitrates, regulation, potential risks and pollutions, economic profitability of projects. The second document states the FNE's opinion on methanization, its challenges and the associated desirable development. The third document is a guide which aims at providing knowledge on methanization, at easing dialogue between actors of a territory, and at elaborating a position and an opinion with respect to a specific methanization project on a territory

Coalbed methane: new frontier

Energy Technology Data Exchange (ETDEWEB)

Eaton, S.

2003-02-01

There are large numbers of stacked coal seams permeated with methane or natural gas in the Western Canadian Sedimentary Basin, and approximately 20 coalbed methane pilot projects are operating in the area, and brief descriptions of some of them were provided. Coalbed methane reserves have a long life cycle. A definition of coalbed methane can be a permeability challenged reservoir. It is not uncommon for coalbed methane wells to flow water for periods varying from 2 to 6 months after completion before the production of natural gas. A made-in-Canada technological solution is being developed by CDX Canada Inc., along with its American parent company. The techniques used by CDX are a marriage between coal mining techniques and oil and gas techniques. A brief description of coalification was provided. Nexen is participating in the production of gas from an Upper Mannville coal at 1 000-metres depth in a nine-well pilot project. The Alberta Foothills are considered prime exploration area since older coal is carried close to the surface by thrusting. CDX Canada uses cavitation completion in vertical wells. Cavitation consists in setting the casing above the coal seam and drilling ahead under balanced. The design of wells for coalbed methane gas is based on rock and fluid mechanics. Hydraulic fracturing completions is also used, as are tiltmeters. An enhanced coalbed methane recovery pilot project is being conducted by the Alberta Research Council at Fenn-Big Valley, located in central Alberta. It injects carbon dioxide, which shows great potential for the reduction of greenhouse gas emissions. 1 figs.

Thermophilic anaerobic oxidation of methane by marine microbial consortia.

Science.gov (United States)

Holler, Thomas; Widdel, Friedrich; Knittel, Katrin; Amann, Rudolf; Kellermann, Matthias Y; Hinrichs, Kai-Uwe; Teske, Andreas; Boetius, Antje; Wegener, Gunter

2011-12-01

The anaerobic oxidation of methane (AOM) with sulfate controls the emission of the greenhouse gas methane from the ocean floor. AOM is performed by microbial consortia of archaea (ANME) associated with partners related to sulfate-reducing bacteria. In vitro enrichments of AOM were so far only successful at temperatures ≤25 °C; however, energy gain for growth by AOM with sulfate is in principle also possible at higher temperatures. Sequences of 16S rRNA genes and core lipids characteristic for ANME as well as hints of in situ AOM activity were indeed reported for geothermally heated marine environments, yet no direct evidence for thermophilic growth of marine ANME consortia was obtained to date. To study possible thermophilic AOM, we investigated hydrothermally influenced sediment from the Guaymas Basin. In vitro incubations showed activity of sulfate-dependent methane oxidation between 5 and 70 °C with an apparent optimum between 45 and 60 °C. AOM was absent at temperatures ≥75 °C. Long-term enrichment of AOM was fastest at 50 °C, yielding a 13-fold increase of methane-dependent sulfate reduction within 250 days, equivalent to an apparent doubling time of 68 days. The enrichments were dominated by novel ANME-1 consortia, mostly associated with bacterial partners of the deltaproteobacterial HotSeep-1 cluster, a deeply branching phylogenetic group previously found in a butane-amended 60 °C-enrichment culture of Guaymas sediments. The closest relatives (Desulfurella spp.; Hippea maritima) are moderately thermophilic sulfur reducers. Results indicate that AOM and ANME archaea could be of biogeochemical relevance not only in cold to moderate but also in hot marine habitats.

Corn industrial wastewater (nejayote): a promising substrate in Mexico for methane production in a coupled system (APCR-UASB).

Science.gov (United States)

España-Gamboa, Elda; Domínguez-Maldonado, Jorge Arturo; Tapia-Tussell, Raul; Chale-Canul, Jose Silvano; Alzate-Gaviria, Liliana

2018-01-01

In Mexico, the corn tortilla is a food of great economic importance. Corn tortilla production generates about 1500-2000 m 3 of wastewater per 600 tons of processed corn. Although this wastewater (also known as nejayote) has a high organic matter content, few studies in Mexico have analyzed its treatment. This study presents fresh data on the potential methane production capacity of nejayote in a two-phase anaerobic digestion system using an Anaerobic-Packed Column Reactor (APCR) to optimize the acidogenic phase and an up-flow anaerobic sludge blanket (UASB) reactor to enhance the methanogenic process. Results indicate that day 8 was ideal to couple the APCR to the UASB reactor. This allowed for a 19-day treatment that yielded 96% COD removal and generated a biogas containing 84% methane. The methane yield was 282 L kg -1 of COD removed . Thus, two-phase anaerobic digestion is an efficient process to treat nejayote; furthermore, this study demonstrated the possibility of using an industrial application by coupling the APCR to the UASB reactor system, in order to assess its feasibility for biomethane generation as a sustainable bioenergy source.

Nitrogen-fixing methane-utilizing bacteria

NARCIS (Netherlands)

Bont, de J.A.M.

1976-01-01

Methane occurs abundantly in nature. In the presence of oxygen this gas may be metabolized by bacteria that are able to use it as carbon and energy source. Several types of bacteria involved in the oxidation of methane have been described in literature. Methane-utilizing bacteria have in

Global diffusive fluxes of methane in marine sediments

Science.gov (United States)

Egger, Matthias; Riedinger, Natascha; Mogollón, José M.; Jørgensen, Bo Barker

2018-06-01

Anaerobic oxidation of methane provides a globally important, yet poorly constrained barrier for the vast amounts of methane produced in the subseafloor. Here we provide a global map and budget of the methane flux and degradation in diffusion-controlled marine sediments in relation to the depth of the methane oxidation barrier. Our new budget suggests that 45-61 Tg of methane are oxidized with sulfate annually, with approximately 80% of this oxidation occurring in continental shelf sediments (methane in steady-state diffusive sediments, we calculate that 3-4% of the global organic carbon flux to the seafloor is converted to methane. We further report a global imbalance of diffusive methane and sulfate fluxes into the sulfate-methane transition with no clear trend with respect to the corresponding depth of the methane oxidation barrier. The observed global mean net flux ratio between sulfate and methane of 1.4:1 indicates that, on average, the methane flux to the sulfate-methane transition accounts for only 70% of the sulfate consumption in the sulfate-methane transition zone of marine sediments.

Methane monitoring from space

Science.gov (United States)

Stephan, C.; Alpers, M.; Millet, B.; Ehret, G.; Flamant, P.

2017-11-01

Methane is one of the strongest anthropogenic greenhouse gases. It contributes by its radiative forcing significantly to the global warming. For a better understanding of climate changes, it is necessary to apply precise space-based measurement techniques in order to obtain a global view on the complex processes that control the methane concentration in the atmosphere. The MERLIN mission is a joint French-German cooperation, on a micro satellite mission for space-based measurement of spatial and temporal gradients of atmospheric methane columns on a global scale. MERLIN will be the first Integrated Path Differential Absorption LIDAR for greenhouse gas monitoring from space. In contrast to passive methane missions, the LIDAR instrument allows measurements at alllatitudes, all-seasons and during night.

Methane Exchange in a Coastal Fen in the First Year after Flooding - A Systems Shift

Science.gov (United States)

Hahn, Juliane; Köhler, Stefan; Glatzel, Stephan; Jurasinski, Gerald

2015-01-01

Background Peatland restoration can have several objectives, for example re-establishing the natural habitat, supporting unique biodiversity attributes or re-initiating key biogeochemical processes, which can ultimately lead to a reduction in greenhouse gas (GHG) emissions. Every restoration measure, however, is itself a disturbance to the ecosystem. Methods Here, we examine an ecosystem shift in a coastal fen at the southern Baltic Sea which was rewetted by flooding. The analyses are based on one year of bi-weekly closed chamber measurements of methane fluxes gathered at spots located in different vegetation stands. During measurement campaigns, we recorded data on water levels, peat temperatures, and chemical properties of peat water. In addition we analyzed the first 20 cm of peat before and after flooding for dry bulk density (DBD), content of organic matter and total amounts of carbon (C), nitrogen (N), sulfur (S), and other nutrients. Results Rewetting turned the site from a summer dry fen into a shallow lake with water levels up to 0.60 m. We observed a substantial die-back of vegetation, especially in stands of sedges (Carex acutiformis Ehrh). Concentrations of total organic carbon and nitrogen in the peat water, as well as dry bulk density and concentrations of C, N and S in the peat increased. In the first year after rewetting, the average annual exchange of methane amounted to 0.26 ± 0.06 kg m-2. This is equivalent to a 190-times increase in methane compared to pre-flooding conditions. Highest methane fluxes occurred in sedge stands which suffered from the heaviest die-back. None of the recorded environmental variables showed consistent relationships with the amounts of methane exchanged. Conclusions Our results suggest that rewetting projects should be monitored not only with regard to vegetation development but also with respect to biogeochemical conditions. Further, high methane emissions that likely occur directly after rewetting by flooding should

Methane synthesis under mild conditions for decentralized applications; Methansynthese unter milden Bedingungen fuer dezentrale Anwendungen

Energy Technology Data Exchange (ETDEWEB)

Schlueter, Michael [DBFZ Deutsches Biomasseforschungszentrum gGmbH, Leipzig (Germany); Roensch, Stefan

2016-08-01

It is a central aim of the German government to significantly reduce the emission of greenhouse gases in the next years. One possibility to reach this aim is the substitution of fossil fuels, especially natural gas, by fuels from biogenic sources (Bio-SNG). However, it is a drawback of Bio-SNG that the production costs are considerably higher than those of fossil natural gas. This work provides an approach to reduce the production costs of Bio-SNG. It is the aim to reduce the process parameters of the methane synthesis. At the same time, it has to be ensured that high methane yields are achieved even at those mild conditions. A procedure for the optimization of the methanation catalyst activity will be presented. If the catalyst is as active as possible even at mild conditions, it will be possible to produce Bio-SNG cost efficient even in small, decentralized scale.

A novel study of methane-rich gas reforming to syngas and its kinetics over semicoke catalyst.

Science.gov (United States)

Zhang, Guojie; Su, Aiting; Qu, Jiangwen; Du, Yannian

2014-01-01

A small-size gasification unit is improved through process optimization to simulate industrial United Gas Improvement Company gasification. It finds that the reaction temperature has important impacts on semicoke catalyzed methane gas mixture. The addition of water vapor can enhance the catalytic activity of reforming, which is due to the fact that addition of water vapor not only removes carbon deposit produced in the reforming and gasification reaction processes, but also participates in gasification reaction with semicoke to generate some active oxygen-containing functional groups. The active oxygen-containing functional groups provide active sites for carbon dioxide reforming of methane, promoting the reforming reaction. It also finds that the addition of different proportions of methane-rich gas can yield synthesis gas with different H2/CO ratio. The kinetics study shows that the semicoke can reduce the activation energy of the reforming reaction and promote the occurrence of the reforming reaction. The kinetics model of methane reforming under the conditions of steam gasification over semicoke is as follows: [Formula in text].

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.)

Methane Ebullition During Simulated Lake Expansion and Permafrost Degradation

Science.gov (United States)

Mazéas, O.; von Fischer, J. C.; Whelan, M.; Rhew, R.

2007-12-01

Methane, a potent greenhouse gas, is emitted by Arctic tundra and lakes. Ebullition, or bubbling, of methane from Arctic lakes has been shown to be a major transport mechanism from the sediment to the atmosphere, and ebullition rates are greatest near the edges of the lakes where active erosion is occurring. In regions of continuous permafrost, Arctic lakes have been expanding in recent decades, attributed to permafrost melting and development of thermokarst. Lake expansion occurs when the margins erode into water, supplying large amounts of organic rich material to the sediment-water interface. This allows carbon that was previously stored in the soil (active layer and permafrost) to become bioavailable and subject to decomposition. An increase in Arctic methane emissions as a result of permafrost thawing and lake expansion would constitute a positive feedback to Arctic warming. In order to better understand these processes, an experiment was initiated in July 2007 at the Barrow Environmental Observatory, Barrow, AK. Different layers of locally collected tundra soil were placed into incubation chambers at the bottom of a shallow (about 1 m deep) lake. Each experimental chamber consists of a bucket fixed underneath an inverted funnel, with a sampling port on top to capture and collect the emitted gases. Gas samples are analyzed for methane and carbon dioxide concentrations, as well as relevant isotopic compositions. Gas sampling has occurred at frequent intervals during the late summer and will continue through the early winter. Three replicates of each layer (active layer, seasonally frozen active layer and permafrost) were incubated, as well as an empty control chamber. An additional chamber containing thawed permafrost and cellulose-rich sawdust was placed for comparison, as cellulose is a major component of plant tissue and the fermentation of the cellulose should yield substrates for methanogenesis. Total production of methane versus organic carbon content of

Production of H2 from aluminium/water reaction and its potential for CO2 methanation

Science.gov (United States)

Khai Phung, Khor; Sethupathi, Sumathi; Siang Piao, Chai

2018-04-01

Carbon dioxide (CO2) is a natural gas that presents in excess in the atmosphere. Owing to its ability to cause global warming, capturing and conversion of CO2 have attracted much attention worldwide. CO2 methanation using hydrogen (H2) is believed to be a promising route for CO2 removal. In the present work, H2 is produced using aluminum-water reaction and tested for its ability to convert CO2 to methane (CH4). Different type of water i.e. tap water, distilled water, deionized water and ultrapure water, concentration of sodium hydroxide (NaOH) (0.2 M to 1.0 M) and particle size of aluminum (45 m to 500 μm) were varied as parameter study. It was found that the highest yield of H2 was obtained using distilled water, 1.0 M of NaOH and 45μm particle size of aluminium. However, the highest yield of methane was achieved using a moderate and progressive H2 production (distilled water, 0.6 M of NaOH and 45 μm particle size of aluminium) which allowed sufficient time for H2 to react with CO2. It was concluded that 1130 ml of H2 can produce about 560 ppm of CH4 within 25 min of batch reaction using nickel catalyst.

Methane in German hard coal mining

International Nuclear Information System (INIS)

Martens, P.N.; Den Drijver, J.

1995-01-01

Worldwide, hard coal mining is being carried out at ever increasing depth, and has, therefore, to cope with correspondingly increasing methane emissions are caused by coal mining. Beside carbon dioxide, chloro-fluoro-carbons (CFCs) and nitrogen oxides, methane is one of the most significant 'greenhouse' gases. It is mainly through the release of such trace gases that the greenhouse effect is brought about. Reducing methane emissions is therefore an important problem to be solved by the coal mining industry. This paper begins by highlighting some of the fundamental principles of methane in hard coal mining. The methane problem in German hard coal mining and the industry's efforts to reduce methane emissions are presented. The future development in German hard coal mining is illustrated by an example which shows how large methane volumes can be managed, while still maintaining high outputs at increasing depth. (author). 7 tabs., 10 figs., 20 refs

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...

Methane anomalies in seawaters of the Ragay Gulf, Philippines: methane cycling and contributions to atmospheric greenhouse gases

International Nuclear Information System (INIS)

Heggie, D.T.; Evans, D.; Bishop, J.H.

1999-01-01

The vertical distribution of methane has been measured in the water column of a semi-enclosed basin, the Ragay Gulf, in the Philippines archipelago. The methane distribution is characterised by unusual mid-water and bottom-water plumes, between 80 and 100 m thick. The plumes are confined to water depths between about 100 and 220 m. where the temperature-depth (a proxy for seawater density) gradient is steepest. Plumes of high methane are 'trapped' within the main thermocline; these are local features, persisting over kilometre-scale distances. Geochemical and geological evidence suggests that the elevated methane concentrations are thermogenic in origin (although an oxidised biogenic origin cannot be ruled out for some of the methane anomalies), and have migrated from the sea floor into the overlying water. The mid and bottom-water methane maxima support fluxes of methane from depth into surface waters and, subsequently, from the oceans to the atmosphere. The average supersaturation of methane in the top 5 m of the sea, at nine locations, was 206±16.5%; range 178-237%. The average estimated sea-air flux was 101 nmole.cm -2 .y -1 and probably represents a minimum flux, because of low wind speeds of <10 knots. These fluxes, we suggest, are supported by seepage from the sea floor and represent naturally occurring fluxes of mostly fossil methane (in contrast to anthropogenic fossil methane), from the sea to the atmosphere. The estimated minimum fluxes of naturally occurring fossil methane are comparable to those biogenic fluxes measured elsewhere in the surface oceans, but are less than those naturally occurring methane inputs from sediments of the Barents Sea. Ragay Gulf fluxes are also less than anthropogenic fluxes measured in areas of petroleum exploration and development, such as the Texas and Louisiana, USA shelf areas

Modeling methane emissions by cattle production systems in Mexico

Science.gov (United States)

Castelan-Ortega, O. A.; Ku Vera, J.; Molina, L. T.

2013-12-01

Methane emissions from livestock is one of the largest sources of methane in Mexico. The purpose of the present paper is to provide a realistic estimate of the national inventory of methane produced by the enteric fermentation of cattle, based on an integrated simulation model, and to provide estimates of CH4 produced by cattle fed typical diets from the tropical and temperate climates of Mexico. The Mexican cattle population of 23.3 million heads was divided in two groups. The first group (7.8 million heads), represents cattle of the tropical climate regions. The second group (15.5 million heads), are the cattle in the temperate climate regions. This approach allows incorporating the effect of diet on CH4 production into the analysis because the quality of forages is lower in the tropics than in temperate regions. Cattle population in every group was subdivided into two categories: cows (COW) and other type of cattle (OTHE), which included calves, heifers, steers and bulls. The daily CH4 production by each category of animal along an average production cycle of 365 days was simulated, instead of using a default emission factor as in Tier 1 approach. Daily milk yield, live weight changes associated with the lactation, and dry matter intake, were simulated for the entire production cycle. The Moe and Tyrrell (1979) model was used to simulate CH4 production for the COW category, the linear model of Mills et al. (2003) for the OTHE category in temperate regions and the Kurihara et al. (1999) model for the OTHE category in the tropical regions as it has been developed for cattle fed tropical diets. All models were integrated with a cow submodel to form an Integrated Simulation Model (ISM). The AFRC (1993) equations and the lactation curve model of Morant and Gnanasakthy (1989) were used to construct the cow submodel. The ISM simulates on a daily basis the CH4 production, milk yield, live weight changes associated with lactation and dry matter intake. The total daily CH

Quantification of the methane concentration using anaerobic oxidation of methane coupled to extracellular electron transfer

Science.gov (United States)

A biofilm anode acclimated with acetate, acetate+methane, and methane growth media for over three years produced a steady current density of 1.6-2.3 mA/m^2 in a microbial electrochemical cell (MxC) fed with methane as the sole electron donor. Geobacter was the dominant genus for...

New alternative energy pathway for chemical pulp mills: From traditional fibers to methane production.

Science.gov (United States)

Rodriguez-Chiang, Lourdes; Vanhatalo, Kari; Llorca, Jordi; Dahl, Olli

2017-07-01

Chemical pulp mills have a need to diversify their end-product portfolio due to the current changing bio-economy. In this study, the methane potential of brown, oxygen delignified and bleached pulp were evaluated in order to assess the potential of converting traditional fibers; as well as microcrystalline cellulose and filtrates; to energy. Results showed that high yields (380mL CH 4 /gVS) were achieved with bleached fibers which correlates with the lower presence of lignin. Filtrates from the hydrolysis process on the other hand, had the lowest yields (253mL CH 4 /gVS) due to the high amount of acid and lignin compounds that cause inhibition. Overall, substrates had a biodegradability above 50% which demonstrates that they can be subjected to efficient anaerobic digestion. An energy and cost estimation showed that the energy produced can be translated into a significant profit and that methane production can be a promising new alternative option for chemical pulp mills. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effect of pre-treatments on methane production potential of energy crops and crop residues

Energy Technology Data Exchange (ETDEWEB)

Lehtomaki, A.; Ronkainen; Rintala, J.A. [Jyvaskla Univ. (Finland). Dept. of Biological and Environmental Sciences; Viinikainen, T.A. [Jyvaskla Univ. (Finland). Dept. of Chemistry

2004-07-01

Energy crops, that is, crops grown specifically for energy purposes are an alternative to food production in areas with sufficient agricultural land. Crop residues are also a potential source of energy. The anaerobic digestion of solid materials is limited by hydrolysis of complex polymeric substances such as lignocellulose. The methane producing potential of ligno cellulosic material is to pretreat the substrate in order to break up the polymer chains to more easily accessible soluble compounds. In this study, three different substrates were used: sugar beet tops, grass hay, and straw of oats. Biological pretreatments were the following: enzyme treatment, composting, white-rot fungi treatment. Also, pretreatment in water was tried. Chemical pretreatments included peracetic acid treatment, and treatment with two different alkalis. Alkaline pretreatments of hay and sugar beet tops have the potential to improve the methane yield. For instance, the yield of grass hay was increased 15 per cent by one particular alkaline treatment. Straw did not respond to any of the treatments tried. 18 refs., 1 tab., 2 figs.

Lambs Fed Fresh Winter Forage Rape (Brassica napus L.) Emit Less Methane than Those Fed Perennial Ryegrass (Lolium perenne L.), and Possible Mechanisms behind the Difference

Science.gov (United States)

Sun, Xuezhao; Henderson, Gemma; Cox, Faith; Molano, German; Harrison, Scott J.; Luo, Dongwen; Janssen, Peter H.; Pacheco, David

2015-01-01

The objectives of this study were to examine long-term effects of feeding forage rape (Brassica napus L.) on methane yields (g methane per kg of feed dry matter intake), and to propose mechanisms that may be responsible for lower emissions from lambs fed forage rape compared to perennial ryegrass (Lolium perenne L.). The lambs were fed fresh winter forage rape or ryegrass as their sole diet for 15 weeks. Methane yields were measured using open circuit respiration chambers, and were 22-30% smaller from forage rape than from ryegrass (averages of 13.6 g versus 19.5 g after 7 weeks, and 17.8 g versus 22.9 g after 15 weeks). The difference therefore persisted consistently for at least 3 months. The smaller methane yields from forage rape were not related to nitrate or sulfate in the feed, which might act as alternative electron acceptors, or to the levels of the potential inhibitors glucosinolates and S-methyl L-cysteine sulfoxide. Ruminal microbial communities in forage rape-fed lambs were different from those in ryegrass-fed lambs, with greater proportions of potentially propionate-forming bacteria, and were consistent with less hydrogen and hence less methane being produced during fermentation. The molar proportions of ruminal acetate were smaller and those of propionate were greater in forage rape-fed lambs, consistent with the larger propionate-forming populations and less hydrogen production. Forage rape contained more readily fermentable carbohydrates and less structural carbohydrates than ryegrass, and was more rapidly degraded in the rumen, which might favour this fermentation profile. The ruminal pH was lower in forage rape-fed lambs, which might inhibit methanogenic activity, shifting the rumen fermentation to more propionate and less hydrogen and methane. The significance of these two mechanisms remains to be investigated. The results suggest that forage rape is a potential methane mitigation tool in pastoral-based sheep production systems. PMID:25803688

Methane-bomb natural gas

International Nuclear Information System (INIS)

Anon.

1993-01-01

About 50% of the so-called 'greenhouse-effect' is not caused by CO 2 , but by more dangerous gases, among them is methane. Natural gas consists to about 98% of methane. In Austria result about 15% of the methane emissions from offtake, storage, transport (pipelines) and distribution from natural gas. A research study of the Research Centre Seibersdorf points out that between 2.5% and 3.6% of the employed natural gas in Austria emits. The impact of this emitted methane is about 29 times worse than the impact of CO 2 (caused for examples by petroleum burning). Nevertheless the Austrian CO 2 -commission states that an increasing use of natural gas would decrease the CO 2 -emissions - but this statement is suspected to be based on wrong assumptions. (blahsl)

Methane hydrates in quaternary climate change

International Nuclear Information System (INIS)

Kennett, J. P.; Hill, T. M.; Behl, R. J.

2005-01-01

The hydrate reservoir in marine sediments is known to contain a large volume of exchangeable carbon stored as solid methane hydrate and associated free gas. This reservoir has been shown to be potentially unstable in response to changing intermediate water temperature and sea level (pressure). Evidence continues to grow for past episodes of major methane release at times of climatic warming. Yet few studies of late Quaternary climate change include methane hydrates as an integral part of the global climate system, in spite of the largest known oscillations at this time in sea level and upper ocean temperature changes for the Cenozoic or earlier, conditions that favor instability of the methane hydrate reservoir. Abrupt increases in atmospheric methane recorded in polar ice cores are widely believed to have resulted, not from ocean-floor methane degassing, but instead from continental wetland activation, a hypothesis thus far unsupported by geological data. Furthermore, as part of this Wetland Methane Hypothesis, the abrupt methane increases have been seen as a response to climatic warming rather than contributing significantly to the change. An alternative view (formulated as the Clathrate Gun Hypothesis) is that the speed, magnitude and timing of abrupt climate change in the recent geologic past are consistent with the process of major degassing of methane hydrates. We summarize aspects of this hypothesis here and needs to test this hypothesis. (Author)

Simulations of atmospheric methane for Cape Grim, Tasmania, to constrain southeastern Australian methane emissions

Directory of Open Access Journals (Sweden)

Z. M. Loh

2015-01-01

Full Text Available This study uses two climate models and six scenarios of prescribed methane emissions to compare modelled and observed atmospheric methane between 1994 and 2007, for Cape Grim, Australia (40.7° S, 144.7° E. The model simulations follow the TransCom-CH4 protocol and use the Australian Community Climate and Earth System Simulator (ACCESS and the CSIRO Conformal-Cubic Atmospheric Model (CCAM. Radon is also simulated and used to reduce the impact of transport differences between the models and observations. Comparisons are made for air samples that have traversed the Australian continent. All six emission scenarios give modelled concentrations that are broadly consistent with those observed. There are three notable mismatches, however. Firstly, scenarios that incorporate interannually varying biomass burning emissions produce anomalously high methane concentrations at Cape Grim at times of large fire events in southeastern Australia, most likely due to the fire methane emissions being unrealistically input into the lowest model level. Secondly, scenarios with wetland methane emissions in the austral winter overestimate methane concentrations at Cape Grim during wintertime while scenarios without winter wetland emissions perform better. Finally, all scenarios fail to represent a~methane source in austral spring implied by the observations. It is possible that the timing of wetland emissions in the scenarios is incorrect with recent satellite measurements suggesting an austral spring (September–October–November, rather than winter, maximum for wetland emissions.

Simultaneous Production of Hydrogen and Methane from Sugar Beet Molasses in a Two Phase Anaerobic Digestion System in UASB Reactors under Thermophilic Temperature (55 Deg C)

Energy Technology Data Exchange (ETDEWEB)

Kongjan, P.; Villafa, S.; Beltran, P.; Min, B.; Angelidaki, I. (Dept. of Environmental Engineering, Technical Univ. of Denmark, DK-2800, Lyngby (Denmark)). e-mail: pak@env.dtu.dk

2008-10-15

Simultaneous production of hydrogen and methane in two sequential stages of acidogenic and methanogenic step was investigated in two serial operated up-flow anaerobic sludge bed (UASB) reactors at thermophilic temperature (55 deg C). Hydrogen production from molasses was carried out in the first reactor at the hydraulic retention time (HRT) of 1 day. Molasses were converted into hydrogen with the yield of 1.3 mole-H{sub 2}/mole-hexose{sub added} or 82.7 ml- H{sub 2}/g-VS{sub added} of molasses, and the hydrogen productivity was 2696 ml-H{sub 2}/dxl{sub reactor}. The effluent (mainly butyrate, acetate and lactate) after the acidogenic process was subsequently fed to the second reactor for methane production at HRT of 3 days. Methane production yield of 255 ml-H{sub 2}/g-VS{sub added} of influent or 130.1 ml-H{sub 2}/g-VS{sub added} of molasses and methane production rate of 1056 ml/dxl{sub reactor} were obtained. Significant decrease of volatile fatty acids (VFAs) was also observed in the effluent of the second reactor. A two phase anaerobic digestion was successfully demonstrated for molasses as a potential substrate to produce hydrogen and subsequent methane in the UASB reactors

Methane Emission and Milk Production of Dairy Cows Grazing Pastures Rich in Legumes or Rich in Grasses in Uruguay

Directory of Open Access Journals (Sweden)

Roberto Gratton

2012-06-01

Full Text Available Understanding the impact of changing pasture composition on reducing emissions of GHGs in dairy grazing systems is an important issue to mitigate climate change. The aim of this study was to estimate daily CH₄ emissions of dairy cows grazing two mixed pastures with contrasting composition of grasses and legumes: L pasture with 60% legumes on Dry Matter (DM basis and G pasture with 75% grasses on DM basis. Milk production and CH₄ emissions were compared over two periods of two weeks during spring using eight lactating Holstein cows in a 2 × 2 Latin square design. Herbage organic matter intake (HOMI was estimated by chromic oxide dilution and herbage organic matter digestibility (OMD was estimated by faecal index. Methane emission was estimated by using the sulfur hexafluoride (SF6 tracer technique adapted to collect breath samples over 5-day periods. OMD (0.71 and HOMI (15.7 kg OM were not affected by pasture composition. Milk production (20.3 kg/d, milk fat yield (742 g/d and milk protein yield (667 g/d were similar for both pastures. This may be explained by the high herbage allowance (30 kg DM above 5 cm/cow which allowed the cows to graze selectively, in particular in grass sward. Similarly, methane emission expressed as absolute value (368 g/d or 516 L/d or expressed as methane yield (6.6% of Gross Energy Intake (GEI was not affected by treatments. In conclusion, at high herbage allowance, the quality of the diet selected by grazing cows did not differ between pastures rich in legumes or rich in grasses, and therefore there was no effect on milk or methane production.

Anaerobic Oxidization of Methane in a Minerotrophic Peatland: Enrichment of Nitrite-Dependent Methane-Oxidizing Bacteria

Science.gov (United States)

Zhu, Baoli; van Dijk, Gijs; Fritz, Christian; Smolders, Alfons J. P.; Pol, Arjan; Jetten, Mike S. M.

2012-01-01

The importance of anaerobic oxidation of methane (AOM) as a methane sink in freshwater systems is largely unexplored, particularly in peat ecosystems. Nitrite-dependent anaerobic methane oxidation (n-damo) was recently discovered and reported to be catalyzed by the bacterium “Candidatus Methylomirabilis oxyfera,” which is affiliated with the NC10 phylum. So far, several “Ca. Methylomirabilis oxyfera” enrichment cultures have been obtained using a limited number of freshwater sediments or wastewater treatment sludge as the inoculum. In this study, using stable isotope measurements and porewater profiles, we investigated the potential of n-damo in a minerotrophic peatland in the south of the Netherlands that is infiltrated by nitrate-rich ground water. Methane and nitrate profiles suggested that all methane produced was oxidized before reaching the oxic layer, and NC10 bacteria could be active in the transition zone where countergradients of methane and nitrate occur. Quantitative PCR showed high NC10 bacterial cell numbers at this methane-nitrate transition zone. This soil section was used to enrich the prevalent NC10 bacteria in a continuous culture supplied with methane and nitrite at an in situ pH of 6.2. An enrichment of nitrite-reducing methanotrophic NC10 bacteria was successfully obtained. Phylogenetic analysis of retrieved 16S rRNA and pmoA genes showed that the enriched bacteria were very similar to the ones found in situ and constituted a new branch of NC10 bacteria with an identity of less than 96 and 90% to the 16S rRNA and pmoA genes of “Ca. Methylomirabilis oxyfera,” respectively. The results of this study expand our knowledge of the diversity and distribution of NC10 bacteria in the environment and highlight their potential contribution to nitrogen and methane cycles. PMID:23042166

Methanization of industrial liquid effluents

International Nuclear Information System (INIS)

Frederic, S.; Lugardon, A.

2007-01-01

In a first part, this work deals with the theoretical aspects of the methanization of the industrial effluents; the associated reactional processes are detailed. The second part presents the technological criteria for choosing the methanization process in terms of the characteristics of the effluent to be treated. Some of the methanization processes are presented with their respective advantages and disadvantages. At last, is described the implementation of an industrial methanization unit. The size and the main choices are detailed: the anaerobic reactor, the control, the valorization aspects of the biogas produced. Some examples of industrial developments illustrate the different used options. (O.M.)

Elimination of methane in exhaust gas from biogas upgrading process by immobilized methane-oxidizing bacteria.

Science.gov (United States)

Wu, Ya-Min; Yang, Jing; Fan, Xiao-Lei; Fu, Shan-Fei; Sun, Meng-Ting; Guo, Rong-Bo

2017-05-01

Biogas upgrading is essential for the comprehensive utilization of biogas as substitute of natural gas. However, the methane in the biogas can be fully recovered during the upgrading process of biogas, and the exhaust gas produced during biogas upgrading may contain a very low concentration of methane. If the exhaust gas with low concentration methane releases to atmosphere, it will be harmful to environment. In addition, the utilization of large amounts of digestate produced from biogas plant is another important issue for the development of biogas industry. In this study, solid digestate was used to produce active carbon, which was subsequently used as immobilized material for methane-oxidizing bacteria (MOB) in biofilter. Biofilter with MOB immobilized on active carbon was used to eliminate the methane in exhaust gas from biogas upgrading process. Results showed porous active carbon was successfully made from solid digestate. The final methane elimination capacity of immobilized MOB reached about 13molh -1 m -3 , which was more 4 times higher than that of MOB without immobilization. Copyright © 2017 Elsevier Ltd. All rights reserved.

Biochemical methane potential (BMP) of artichoke waste: the inoculum effect.

Science.gov (United States)

Fabbri, Andrea; Serranti, Silvia; Bonifazi, Giuseppe

2014-03-01

The aim of this work was to investigate anaerobic digestibility of artichoke waste resulting from industrial transformation. A series of batch anaerobic digestion tests was performed in order to evaluate the biochemical methane potential of the matrix in respect of the process. A comparison of the different performances of the laboratory-scale reactors operating in mesophilic conditions and utilizing three different values of the inoculum/substrate ratio was carried out. The best performance was achieved with an inoculum/substrate ratio of 2. Artichoke-processing byproducts showed a classical organic waste decomposition behaviour: a fast start-up phase, an acclimation stage, and a final stabilization phase. Following this approach, artichoke waste reached chemical oxygen demand removal of about 90% in 40 days. The high methane yield (average 408.62 mL CH4 gvs (-1) voltatile solids), makes artichoke waste a good product to be utilized in anaerobic digestion plants for biogas production.

Hot reactions of 13N in solid methane at 77 K

International Nuclear Information System (INIS)

Fiergolla, J.; Nebeling, B.; Roessler, K.

1987-09-01

The chemical reactions of recoil- 13 N were studied in solid methane at 77 K. 13 N was generated via the the nuclear reaction 12 C(d,n) 13 N. The radiation dose deliverd by the 8.5 MeV deuterons amounted to D * = 0.6 eV per target molecule. The products formed by high energy chemical processes (hot chemistry) were analyzed by radio-gaschromatography. 13 NH 3 with 52% and CH 3 13 NH 2 with 25% radiochemical yield were found to be the main products. HC 13 N was not formed, but CH 3 13 CN amounts to 4%. For the more complex products carbon chain prolongation is prefered over multiple methylation such as show the yields of 8% for C 2 H 5 13 NH 2 and 3% (CH 3 ) 2 13 NH. (CH 3 ) 3 N was not detected. The formation of 13 NH 3 is due to hydrogen abstraction, that of CH 3 13 NH 2 due to insertion of NH radical into the C-H bond of CH 4 . Another, however, less probable pathway could be the insertion of 13 N into methane. The methylamine radical may react with another methane molecule via hydrogen transfer to methylamine or attack to CH 4 to dimethylamine. The 13 N-products were formed with high radiochemical purity and can potentially be applied for the synthesis of 13 N-radiopharmaceuticals. The reactions studied bear also informations on chemical processes in space (e.g. solar wind interactions with comets or interplanetary dust). 13 N-high energy chemical products are, however, of a less exobiological significance then those formed by hot carbon atoms, e.g. in the 'mirror' system 11 C/NH 3 (s). (orig.) [de

Hedging Yield with Weather Derivatives: A Role for Options

OpenAIRE

Manfredo, Mark R.; Richards, Timothy J.

2005-01-01

While there are few risk management alternatives available to specialty crop growers, weather derivatives provide an important advancement. As with the use of any derivatives contract, the behavior of the basis will ultimately determine the net-hedged outcome. However, when using weather derivatives to hedge yield risks for specialty crops, growers face a unique form of basis risk because weather (temperature) and yield are nonlinearly related. Using the forecast encompassing principle, this ...

Historical methane hydrate project review

Science.gov (United States)

Collett, Timothy; Bahk, Jang-Jun; Frye, Matt; Goldberg, Dave; Husebo, Jarle; Koh, Carolyn; Malone, Mitch; Shipp, Craig; Torres, Marta

2013-01-01

In 1995, U.S. Geological Survey made the first systematic assessment of the volume of natural gas stored in the hydrate accumulations of the United States. That study, along with numerous other studies, has shown that the amount of gas stored as methane hydrates in the world greatly exceeds the volume of known conventional gas resources. However, gas hydrates represent both a scientific and technical challenge and much remains to be learned about their characteristics and occurrence in nature. Methane hydrate research in recent years has mostly focused on: (1) documenting the geologic parameters that control the occurrence and stability of gas hydrates in nature, (2) assessing the volume of natural gas stored within various gas hydrate accumulations, (3) analyzing the production response and characteristics of methane hydrates, (4) identifying and predicting natural and induced environmental and climate impacts of natural gas hydrates, and (5) analyzing the effects of methane hydrate on drilling safety.Methane hydrates are naturally occurring crystalline substances composed of water and gas, in which a solid water-­‐lattice holds gas molecules in a cage-­‐like structure. The gas and water becomes a solid under specific temperature and pressure conditions within the Earth, called the hydrate stability zone. Other factors that control the presence of methane hydrate in nature include the source of the gas included within the hydrates, the physical and chemical controls on the migration of gas with a sedimentary basin containing methane hydrates, the availability of the water also included in the hydrate structure, and the presence of a suitable host sediment or “reservoir”. The geologic controls on the occurrence of gas hydrates have become collectively known as the “methane hydrate petroleum system”, which has become the focus of numerous hydrate research programs.Recognizing the importance of methane hydrate research and the need for a coordinated

Air conditioning with methane: Efficiency and economics optimization parameters

International Nuclear Information System (INIS)

Mastrullo, R.; Sasso, M.; Sibilio, S.; Vanoli, R.

1992-01-01

This paper presents an efficiency and economics evaluation method for methane fired cooling systems. Focus is on direct flame two staged absorption systems and alternative engine driven compressor sets. Comparisons are made with conventional vapour compression plants powered by electricity supplied by the national grid. A first and second law based thermodynamics analysis is made in which fuel use coefficients and exergy yields are determined. The economics analysis establishes annual energy savings, unit cooling energy production costs, payback periods and economics/efficiency optimization curves useful for preliminary feasibility studies

Evaluation of methane emissions from Taiwanese paddies

International Nuclear Information System (INIS)

Liu, C.-W.; Wu, C.-Y.

2004-01-01

The main greenhouse gases are carbon dioxide, methane and nitrous oxide. Methane is the most important because the warming effect of methane is 21 times greater than that of carbon dioxide. Methane emitted from rice paddy fields is a major source of atmospheric methane. In this work, a methane emission model (MEM), which integrates climate change, plant growth and degradation of soil organic matter, was applied to estimate the emission of methane from rice paddy fields in Taiwan. The estimated results indicate that much methane is emitted during the effective tillering and booting stages in the first crop season and during the transplanting stage in the second crop season in a year. Sensitivity analysis reveals that the temperature is the most important parameter that governs the methane emission rate. The order of the strengths of the effects of the other parameters is soil pH, soil water depth (SWD) and soil organic matter content. The masses of methane emitted from rice paddy fields of Taiwan in the first and second crop seasons are 28,507 and 350,231 tons, respectively. The amount of methane emitted during the second crop season is 12.5 times higher than that emitted in the first crop season. With a 12% reduction in planted area during the second crop season, methane emission could be reduced by 21%. In addition, removal of rice straw left from the first crop season and increasing the depth of flooding to 25 cm are also strategies that could help reduce annual emission by up to 18%

Methane production by treating vinasses from hydrous ethanol using a modified UASB reactor

Science.gov (United States)

2012-01-01

Background A modified laboratory-scale upflow anaerobic sludge blanket (UASB) reactor was used to obtain methane by treating hydrous ethanol vinasse. Vinasses or stillage are waste materials with high organic loads, and a complex composition resulting from the process of alcohol distillation. They must initially be treated with anaerobic processes due to their high organic loads. Vinasses can be considered multipurpose waste for energy recovery and once treated they can be used in agriculture without the risk of polluting soil, underground water or crops. In this sense, treatment of vinasse combines the elimination of organic waste with the formation of methane. Biogas is considered as a promising renewable energy source. The aim of this study was to determine the optimum organic loading rate for operating a modified UASB reactor to treat vinasse generated in the production of hydrous ethanol from sugar cane molasses. Results The study showed that chemical oxygen demand (COD) removal efficiency was 69% at an optimum organic loading rate (OLR) of 17.05 kg COD/m3-day, achieving a methane yield of 0.263 m3/kg CODadded and a biogas methane content of 84%. During this stage, effluent characterization presented lower values than the vinasse, except for potassium, sulfide and ammonia nitrogen. On the other hand, primers used to amplify the 16S-rDNA genes for the domains Archaea and Bacteria showed the presence of microorganisms which favor methane production at the optimum organic loading rate. Conclusions The modified UASB reactor proposed in this study provided a successful treatment of the vinasse obtained from hydrous ethanol production. Methanogen groups (Methanobacteriales and Methanosarcinales) detected by PCR during operational optimum OLR of the modified UASB reactor, favored methane production. PMID:23167984

Methane production by treating vinasses from hydrous ethanol using a modified UASB reactor

Directory of Open Access Journals (Sweden)

España-Gamboa Elda I

2012-11-01

Full Text Available Abstract Background A modified laboratory-scale upflow anaerobic sludge blanket (UASB reactor was used to obtain methane by treating hydrous ethanol vinasse. Vinasses or stillage are waste materials with high organic loads, and a complex composition resulting from the process of alcohol distillation. They must initially be treated with anaerobic processes due to their high organic loads. Vinasses can be considered multipurpose waste for energy recovery and once treated they can be used in agriculture without the risk of polluting soil, underground water or crops. In this sense, treatment of vinasse combines the elimination of organic waste with the formation of methane. Biogas is considered as a promising renewable energy source. The aim of this study was to determine the optimum organic loading rate for operating a modified UASB reactor to treat vinasse generated in the production of hydrous ethanol from sugar cane molasses. Results The study showed that chemical oxygen demand (COD removal efficiency was 69% at an optimum organic loading rate (OLR of 17.05 kg COD/m3-day, achieving a methane yield of 0.263 m3/kg CODadded and a biogas methane content of 84%. During this stage, effluent characterization presented lower values than the vinasse, except for potassium, sulfide and ammonia nitrogen. On the other hand, primers used to amplify the 16S-rDNA genes for the domains Archaea and Bacteria showed the presence of microorganisms which favor methane production at the optimum organic loading rate. Conclusions The modified UASB reactor proposed in this study provided a successful treatment of the vinasse obtained from hydrous ethanol production. Methanogen groups (Methanobacteriales and Methanosarcinales detected by PCR during operational optimum OLR of the modified UASB reactor, favored methane production.

Methane production by treating vinasses from hydrous ethanol using a modified UASB reactor.

Science.gov (United States)

España-Gamboa, Elda I; Mijangos-Cortés, Javier O; Hernández-Zárate, Galdy; Maldonado, Jorge A Domínguez; Alzate-Gaviria, Liliana M

2012-11-21

A modified laboratory-scale upflow anaerobic sludge blanket (UASB) reactor was used to obtain methane by treating hydrous ethanol vinasse. Vinasses or stillage are waste materials with high organic loads, and a complex composition resulting from the process of alcohol distillation. They must initially be treated with anaerobic processes due to their high organic loads. Vinasses can be considered multipurpose waste for energy recovery and once treated they can be used in agriculture without the risk of polluting soil, underground water or crops. In this sense, treatment of vinasse combines the elimination of organic waste with the formation of methane. Biogas is considered as a promising renewable energy source. The aim of this study was to determine the optimum organic loading rate for operating a modified UASB reactor to treat vinasse generated in the production of hydrous ethanol from sugar cane molasses. The study showed that chemical oxygen demand (COD) removal efficiency was 69% at an optimum organic loading rate (OLR) of 17.05 kg COD/m3-day, achieving a methane yield of 0.263 m3/kg CODadded and a biogas methane content of 84%. During this stage, effluent characterization presented lower values than the vinasse, except for potassium, sulfide and ammonia nitrogen. On the other hand, primers used to amplify the 16S-rDNA genes for the domains Archaea and Bacteria showed the presence of microorganisms which favor methane production at the optimum organic loading rate. The modified UASB reactor proposed in this study provided a successful treatment of the vinasse obtained from hydrous ethanol production.Methanogen groups (Methanobacteriales and Methanosarcinales) detected by PCR during operational optimum OLR of the modified UASB reactor, favored methane production.

Reducing methane emissions from ruminant animals

Energy Technology Data Exchange (ETDEWEB)

Mathison, G.W.; Okine, E.K.; McAllister, T.A.; Dong, Y.; Galbraith, J.; Dmytruk, O.I.N. [University of Alberta, Edmonton, AB (Canada). Dept. of Agriculture, Food and Nutrition Science

1998-09-01

In 1992 it was estimated that 30 x 10{sup 12}g more methane was emitted into the atmosphere than was removed, with animals being considered the largest single anthropogenic source. Ruminants produce 97% of the methane generated in enteric fermentation by animals. Estimates for methane emissions from animal wastes vary between 6 and 31% of that produced directly by the animal, with the most likely value being between 5 and 10% globally. Methane inhibitors can reduce methane emissions to zero in the short term but due to microbial adaptation the effects of these compounds are quickly neutralized and feed intake is often depressed. Methane emissions per unit of feed consumed from sheep and cattle fed hay diets appear to be quite similar but differences between other ruminants have been measured. The most practical way of influencing methane emissions per unit product is to increase productivity level since the proportion of feed energy required to just maintain the animal will be reduced, methane production falls with increased intake level, and the animal may go to market sooner. The most promising avenues for future research for reducing methanogenesis are the development of new products for reducing protozoal numbers in the rumen and the use of bacterocins or other compounds which specifically target methanogenic bacteria.

Wave-induced release of methane : littoral zones as a source of methane in lakes

OpenAIRE

Hofmann, Hilmar; Federwisch, Luisa; Peeters, Frank

2010-01-01

This study investigates the role of surface waves and the associated disturbance of littoral sediments for the release and later distribution of dissolved methane in lakes. Surface wave field, wave-induced currents, acoustic backscatter strength, and the concentration and distribution of dissolved methane were measured simultaneously in Lake Constance, Germany. The data indicate that surface waves enhance the release of dissolved methane in the shallow littoral zone via burst-like releases of...

Direct Activation Of Methane

KAUST Repository

Basset, Jean-Marie; Sun, Miao; Caps, Valerie; Pelletier, Jeremie; Abou-Hamad, Edy

2013-01-01

Heteropolyacids (HPAs) can activate methane at ambient temperature (e.g., 20.degree. C.) and atmospheric pressure, and transform methane to acetic acid, in the absence of any noble metal such as Pd). The HPAs can be, for example, those with Keggin

Anaerobic co-digestion of Tunisian green macroalgae Ulva rigida with sugar industry wastewater for biogas and methane production enhancement.

Science.gov (United States)

Karray, Raida; Karray, Fatma; Loukil, Slim; Mhiri, Najla; Sayadi, Sami

2017-03-01

Ulva rigida is a green macroalgae, abundantly available in the Mediterranean which offers a promising source for the production of valuable biomaterials, including methane. In this study, anaerobic digestion assays in a batch mode was performed to investigate the effects of various inocula as a mixture of fresh algae, bacteria, fungi and sediment collected from the coast of Sfax, on biogas production from Ulva rigida. The results revealed that the best inoculum to produce biogas and feed an anaerobic reactor is obtained through mixing decomposed macroalgae with anaerobic sludge and water, yielding into 408mL of biogas. The process was then investigated in a sequencing batch reactor (SBR) which led to an overall biogas production of 375mL with 40% of methane. Further co-digestion studies were performed in an anaerobic up-flow bioreactor using sugar wastewater as a co-substrate. A high biogas production yield of 114mL g -1 VS added was obtained with 75% of methane. The co-digestion proposed in this work allowed the recovery of natural methane, providing a promising alternative to conventional anaerobic microbial fermentation using Tunisian green macroalgae. Finally, in order to identify the microbial diversity present in the reactor during anaerobic digestion of Ulva rigida, the prokaryotic diversity was investigated in this bioreactor by the denaturing gradient gel electrophoresis (DGGE) method targeting the 16S rRNA gene. Copyright © 2016 Elsevier Ltd. All rights reserved.

Methane emissions from coal mining

International Nuclear Information System (INIS)

Boyer, C.M.; Kelafant, J.R.; Kuuskraa, V.A.; Manger, K.C.; Kruger, D.

1990-09-01

The report estimates global methane emissions from coal mining on a country specific basis, evaluates the technologies available to degasify coal seams and assesses the economics of recovering methane liberated during mining. 33 to 64 million tonnes were liberated in 1987 from coal mining, 75 per cent of which came from China, the USSR, Poland and the USA. Methane emissions from coal mining are likely to increase. Emission levels vary between surface and underground mines. The methane currently removed from underground mines for safety reasons could be used in a number of ways, which may be economically attractive. 55 refs., 19 figs., 24 tabs

Optimization geometries of a vortex gliding-arc reactor for partial oxidation of methane

International Nuclear Information System (INIS)

Guofeng, Xu; Xinwei, Ding

2012-01-01

The effects of the geometry of gliding-arc reactor – such as distance between the electrodes, outlet diameter, and inlet position – on the reactor characteristics (methane conversion, hydrogen yield, and energy efficiency) have not been fully investigated. In this paper, AC gliding-arc reactors including the vortex flow configuration are designed to produce hydrogen from the methane by partial oxidation. The influence of vortex flow configuration on the reactor characteristics is also studied by varying the inlet position. When the inlet of the gliding-arc reactor is positioned close to the outlet, reverse vortex flow reactor (RVFR), the maximum energy efficiency reaches 50% and the yields of hydrogen and carbon monoxide are 40% and 65%, respectively. As the distance between electrodes increases from 5 mm to 15 mm, both hydrogen yield and energy efficiency increase approximately 10% for the RVFR. The energy efficiency and hydrogen yield are highest when the ratio of the outlet diameter to the inner diameter is 0.5 for the RVFR. Experimental results indicate that the flow field in the plasma reactor has an important influence on the reactor performance. Furthermore, hydrogen production increases as the number of feed gas flows in contact with the plasma zone increases. -- Highlights: ► Gliding-arc reactors were designed to produce hydrogen for studying the characteristics of the vortex flow reactor. ► Hydrogen yield of reverse vortex flow reactor was 10% higher than that of forward vortex flow reactor. ► Maximum energy efficiency was 50% for reverse vortex flow reactor. ► If discharge power was supplied to the reactors, the reactor performance increased with increasing distance between electrodes. ► Optimum ratio of the outlet and inner diameter was 1/2.

Gas-liquid equilibrium in mixtures of methane + m-xylene, and methane + m-cresol

Energy Technology Data Exchange (ETDEWEB)

Simnick, J J; Sebastian, H M; Lin, H M; Chao, K C

1979-01-01

Compositions of saturated equilibrium liquid and vapor phases as determined in a flow apparatus for methane + m-xylene mixtures at 370/sup 0/, 450/sup 0/, 520/sup 0/, and 600/sup 0/F (190/sup 0/, 230/sup 0/, 270/sup 0/, and 310/sup 0/C) and up to 200 atm, and for methane + m-cresol at 370/sup 0/, 520/sup 0/, 660/sup 0/, and 730/sup 0/F (190/sup 0/, 270/sup 0/, 350/sup 0/, and 390/sup 0/C) and up to 250 atm. Compared with published data on its solubility in benzene, methane appears to be more soluble in m-xylene at similar conditions but substantially less soluble in m-cresol. This difference indicates that the functional groups CH/sub 3/ and OH play different roles in determining the solubility of methane.

Electrocatalytic oxidation of methane: investigations of new catalysts to be used in a solid polymer electrolyte methane fuel-cell; Oxydation electrocatalytique du methane: recherche de catalyseurs en vue d'une application a une pile au methane a electrolyte polymere solide

Energy Technology Data Exchange (ETDEWEB)

Berthelot, S

1998-07-01

This thesis evaluated the performances of many catalysts facing the methane oxidation which is a critical step in methane fuel cells development. In a first part the study of the methane electro-oxidation has been realized by classical electrochemical technics on many electrodes to determine the most active ones. In a second part the in situ reflection infra-red spectroscopy allowed to identify, during the methane oxidation, the adsorbed species on the electrode and the reaction products. These results also help the understanding of the part of the concerned materials mechanisms in the methane oxidation and then to optimize them for a whole oxidation of the methane in carbon dioxide. The final objective is the use of the methane in a PEMFC fuel cell type. A comparison with the methanol and C2 hydrocarbons behaviour, such as the ethane the ethylene and the acetylene, has been done to evaluate the performances. (A.L.B.)

Influence of feeding supplements of almond hulls and ensiled citrus pulp on the milk production, milk composition, and methane emissions of dairy cows.

Science.gov (United States)

Williams, S R O; Chaves, A V; Deighton, M H; Jacobs, J L; Hannah, M C; Ribaux, B E; Morris, G L; Wales, W J; Moate, P J

2018-03-01

Almond hulls and citrus pulp have been fed to dairy cows with variable responses for milk production, but no information exists on their effect on enteric methane emissions. This experiment examined the effects of dietary supplementation with either almond hulls or ensiled citrus pulp on the milk yield, milk composition, and enteric methane emissions of dairy cows. Thirty-two Holstein dairy cows in mid lactation were offered 1 of 3 diets over a 28-d experiment. Twelve cows received a control (CON) diet, 10 cows a diet containing almond hulls (ALH), and 10 cows a diet containing ensiled citrus pulp (CIT). All cows were offered 6.0 kg of dry matter (DM)/d of crushed corn, 2.0 kg of DM/d of cold-pressed canola, and 0.2 kg of DM/d of a mineral mix. In addition, cows fed the CON diet were offered 14.5 kg of DM/d of alfalfa cubes; cows fed the ALH diet were offered 10.5 kg of DM/d of alfalfa cubes and 4.0 kg of DM/d of almond hulls; and cows on the CIT diet were offered 11.5 kg of DM/d of alfalfa cubes and 3.0 kg of DM/d of ensiled citrus pulp. Milk yield was measured daily and milk composition was measured on 4 d of each week. Individual cow methane emissions were measured by a sulfur hexafluoride tracer technique on d 24 to 28 of the experiment. The mean milk yield of cows fed the CON diet (27.4 kg/d) was greater than the mean milk yield of cows fed the ALH diet (24.6 kg/cow per day), whereas the mean milk yield of cows fed the CIT diet (26.2 kg/cow per day) was not different from the mean milk yield from cows fed the other 2 diets. Dietary treatment did not influence the concentrations of milk fat, protein, and lactose or fat yields, but the mean protein yield from cows fed the CON diet (0.87 kg/d) was greater than that from cows fed the ALH diet (0.78 kg/d) but not different to those fed the CIT diet (0.85 kg/d). In general, we found no differences in the proportion of individual fatty acids in milk. The mean pH of ruminal fluid from cows offered the CON diet was not

Ebullitive methane emissions from oxygenated wetland streams

Science.gov (United States)

Crawford, John T.; Stanley, Emily H.; Spawn, Seth A.; Finlay, Jacques C.; Striegl, Robert G.

2014-01-01

Stream and river carbon dioxide emissions are an important component of the global carbon cycle. Methane emissions from streams could also contribute to regional or global greenhouse gas cycling, but there are relatively few data regarding stream and river methane emissions. Furthermore, the available data do not typically include the ebullitive (bubble-mediated) pathway, instead focusing on emission of dissolved methane by diffusion or convection. Here, we show the importance of ebullitive methane emissions from small streams in the regional greenhouse gas balance of a lake and wetland-dominated landscape in temperate North America and identify the origin of the methane emitted from these well-oxygenated streams. Stream methane flux densities from this landscape tended to exceed those of nearby wetland diffusive fluxes as well as average global wetland ebullitive fluxes. Total stream ebullitive methane flux at the regional scale (103 Mg C yr−1; over 6400 km2) was of the same magnitude as diffusive methane flux previously documented at the same scale. Organic-rich stream sediments had the highest rates of bubble release and higher enrichment of methane in bubbles, but glacial sand sediments also exhibited high bubble emissions relative to other studied environments. Our results from a database of groundwater chemistry support the hypothesis that methane in bubbles is produced in anoxic near-stream sediment porewaters, and not in deeper, oxygenated groundwaters. Methane interacts with other key elemental cycles such as nitrogen, oxygen, and sulfur, which has implications for ecosystem changes such as drought and increased nutrient loading. Our results support the contention that streams, particularly those draining wetland landscapes of the northern hemisphere, are an important component of the global methane cycle.

Mechanical design of mussel byssus: material yield enhances attachment strength

Science.gov (United States)

Bell; Gosline

1996-01-01

The competitive dominance of mussels in the wave-swept rocky intertidal zone is in part due to their ability to maintain a secure attachment. Mussels are tethered to the substratum by a byssus composed of numerous extracellular, collagenous threads secreted by the foot. Each byssal thread has three serially arranged parts: a corrugated proximal region, a smooth distal region and an adhesive plaque. This study examines the material and structural properties of the byssal threads of three mussel species: Mytilus californianus, M. trossulus, and M. galloprovincialis. Tensile tests in general reveal similar material properties among species: the proximal region has a lower initial modulus, a lower ultimate stress and a higher ultimate strain than the distal region. The distal region also yields at a stress well below its ultimate value. In whole thread tests, the proximal region and adhesive plaque are common sites of structural failure and are closely matched in strength, while the distal region appears to be excessively strong. We propose that the high strength of the distal region is the byproduct of a material designed to yield and extend before structural failure occurs. Experimental and theoretical evidence is presented suggesting that thread yield and extensibility provide two important mechanisms for increasing the overall attachment strength of the mussel: (1) the reorientation of threads towards the direction of applied load, and (2) the 'recruitment' of more threads into tension and the consequent distribution of applied load over a larger cross-sectional area, thereby reducing the stress on each thread. This distal region yield behavior is most striking for M. californianus and may be a key to its success in extreme wave-swept environments.

Methane production and characteristics of the microbial community in the co-digestion of spent mushroom substrate with dairy manure.

Science.gov (United States)

Luo, Xiaosha; Yuan, Xufeng; Wang, Shiyu; Sun, Fanrong; Hou, Zhanshan; Hu, Qingxiu; Zhai, Limei; Cui, Zongjun; Zou, Yajie

2018-02-01

Spent mushroom substrate (SMS) is a potential biomass material generated during mushroom cultivation. In this study, the methane yield and microbial community resulting from co-digestion of SMS and dairy manure (DM) at different mixing ratios (0:4, 1:1, 3:1, and 1:3), were evaluated. Co-digestion analysis showed that the methane yield from the mixtures was 6%-61% higher than the yield from SMS or DM alone, indicating a synergistic effect of co-digestion of SMS with DM. For the SMS of F.velutipes (SFv) and P.erygii var. tuoliensis (SPt), co-digestion of DM/SMS at a ratio of 1:1 was optimal, but for the SMS of P. eryngi (SPe), co-digestion of DM/SMS at a ratio of 3:1 was ideal. The pH at all co-digestion ratios was in the range of 6.8-8.0, indicating that adding DM could increase the systemic buffering capacity. Methanosaetaceae was shown to be the predominant methanogens present during the co-digestion of DM/SMS. Copyright © 2017 Elsevier Ltd. All rights reserved.

Methane generated from graphite--tritium interaction

International Nuclear Information System (INIS)

Coffin, D.O.; Walthers, C.R.

1979-01-01

When hydrogen isotopes are separated by cryogenic distillation, as little as 1 ppM of methane will eventually plug the still as frost accumulates on the column packings. Elemental carbon exposed to tritium generates methane spontaneously, and yet some dry transfer pumps, otherwise compatible with tritium, convey the gas with graphite rotors. This study was to determine the methane production rate for graphite in tritium. A pump manufacturer supplied graphite samples that we exposed to tritium gas at 0.8 atm. After 137 days we measured a methane synthesis rate of 6 ng/h per cm 2 of graphite exposed. At this rate methane might grow to a concentration of 0.01 ppM when pure tritium is transferred once through a typical graphite--rotor transfer pump. Such a low methane level will not cause column blockage, even if the cryogenic still is operated continuously for many years

Methane hydrates in nature - Current knowledge and challenges

Science.gov (United States)

Collett, Timothy S.

2014-01-01

Recognizing the importance of methane hydrate research and the need for a coordinated effort, the United States Congress enacted the Methane Hydrate Research and Development Act of 2000. At the same time, the Ministry of International Trade and Industry in Japan launched a research program to develop plans for a methane hydrate exploratory drilling project in the Nankai Trough. India, China, the Republic of Korea, and other nations also have established large methane hydrate research and development programs. Government-funded scientific research drilling expeditions and production test studies have provided a wealth of information on the occurrence of methane hydrates in nature. Numerous studies have shown that the amount of gas stored as methane hydrates in the world may exceed the volume of known organic carbon sources. However, methane hydrates represent both a scientific and technical challenge, and much remains to be learned about their characteristics and occurrence in nature. Methane hydrate research in recent years has mostly focused on: (1) documenting the geologic parameters that control the occurrence and stability of methane hydrates in nature, (2) assessing the volume of natural gas stored within various methane hydrate accumulations, (3) analyzing the production response and characteristics of methane hydrates, (4) identifying and predicting natural and induced environmental and climate impacts of natural methane hydrates, (5) analyzing the methane hydrate role as a geohazard, (6) establishing the means to detect and characterize methane hydrate accumulations using geologic and geophysical data, and (7) establishing the thermodynamic phase equilibrium properties of methane hydrates as a function of temperature, pressure, and gas composition. The U.S. Department of Energy (DOE) and the Consortium for Ocean Leadership (COL) combined their efforts in 2012 to assess the contributions that scientific drilling has made and could continue to make to advance

Methane production and digestion of different physical forms of rapeseed as fat supplements in dairy cows

DEFF Research Database (Denmark)

Brask, Maike; Lund, Peter; Weisbjerg, Martin Riis

2013-01-01

The purpose of this experiment was to study the effect of the physical form of rapeseed fat on methane (CH4) mitigation properties, feed digestion, and rumen fermentation. Four lactating ruminal-, duodenal-, and ileal-cannulated Danish Holstein dairy cows (143 d in milk, milk yield of 34.3 kg) were...

Ultimate justification: Wittgenstein and medical ethics.

Science.gov (United States)

Hughes, J

1995-02-01

Decisions must be justified. In medical ethics various grounds are given to justify decisions, but ultimate justification seems illusory and little considered. The philosopher Wittgenstein discusses the problem of ultimate justification in the context of general philosophy. His comments, nevertheless, are pertinent to ethics. From a discussion of Wittgensteinian notions, such as 'bedrock', the idea that 'ultimate' justification is grounded in human nature as such is derived. This discussion is relevant to medical ethics in at least five ways: it shows generally what type of certainty there is in practical ethics; it seems to imply some objective foundation to our ethical judgements; it squares with our experience of making ethical decisions; it shows something of the nature of moral arguments; and, finally, it has implications for teaching medicine and ethics.

Optimization of biohydrogen and methane recovery within a cassava ethanol wastewater/waste integrated management system.

Science.gov (United States)

Wang, Wen; Xie, Li; Luo, Gang; Zhou, Qi; Lu, Qin

2012-09-01

Thermophilic co-fermentation of cassava stillage (CS) and cassava excess sludge (CES) were investigated for hydrogen and methane production. The highest hydrogen yield (37.1 ml/g-total-VS added) was obtained at VS(CS)/VS(CES) of 7:1, 17% higher than that with CS digestion alone. The CES recycle enhanced the substrate utilization and improved the buffer capacity. Further increase the CES fraction led to changed VFA distribution and more hydrogen consumption. FISH analysis revealed that both hydrogen producing bacteria and hydrogen consuming bacteria were enriched after CES recycled, and the acetobacteria percentage increased to 12.4% at VS(CS)/VS(CES) of 6:2. Relatively high efficient and stable hydrogen production was observed at VS(CS)/VS(CES) of 5:3 without pH adjusted and any pretreatment. The highest total energy yield, the highest COD and VS degradation were obtained at VS(CS)/VS(CES) of 7:1. GFC analysis indicated that the hydrolysis behavior was significantly improved by CES recycle at both hydrogen and methane production phase. Copyright © 2012 Elsevier Ltd. All rights reserved.

Biogenic methane potential of marine sediments. Application of chemical thermodynamics

Energy Technology Data Exchange (ETDEWEB)

Arning, E.T.; Schulz, H.M. [Helmholtz Centre Potsdam GFZ, Potsdam (Germany); Berk, W. van [Technical Univ. of Clausthal (Germany). Dept. of Hydrogeology

2013-08-01

Accumulations of biogenic methane-dominated gas are widespread and occur in a variety of depositional settings and rock types. However, the potential of biogenic methane remains underexplored. This is mainly due to the fact that quantitative assessments applying numerical modeling techniques for exploration purposes are generally lacking to date. Biogenic methane formation starts in relatively shallow marine sediments below the sulfate reduction zone. When sulfate is exhausted, methanogenesis via the CO{sub 2} reduction pathway is often the dominant biogenic methane formation process in marine sediments (Claypool and Kaplan, 1974). The process can be simplified by the reaction: 2CH{sub 2}O + Ca{sup 2+} + H{sub 2}O {yields} CH{sub 4} + CaCO{sub 3} + 2H{sup +}. The products of early diagenetic reactions initiate coupled equilibrium reactions that induce a new state of chemical equilibrium among minerals, pore water and gas. The driving force of the complex biogeochemical reactions in sedimentary environments during early diagenesis is the irreversible redox-conversion of organic matter. Early diagenetic formation of biogenic methane shortly after deposition ('early diagenesis') was retraced using PHREEQC computer code that is applied to calculate homogenous and heterogeneous mass-action equations in combination with one-dimensional diffusion driven transport (Parkhurst and Appelo, 1999). Our modeling approach incorporates interdependent diagenetic reactions evolving into a diffusive multi-component and multiphase system by means of thermodynamic equilibrium calculations of species distribution (Arning et al., 2011, 2012, 2013). Reaction kinetics of organic carbon conversion is integrated into the set of equilibrium reactions by defining type and amount of converted organic matter in a certain time step. It is the aim (1) to calculate quantitatively thermodynamic equilibrium conditions (composition of pore water, mineral phase and gas phase assemblage) in

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

Methane Flux and Authigenic Carbonate in Shallow Sediments Overlying Methane Hydrate Bearing Strata in Alaminos Canyon, Gulf of Mexico

Directory of Open Access Journals (Sweden)

Joseph P. Smith

2014-09-01

Full Text Available In June 2007 sediment cores were collected in Alaminos Canyon, Gulf of Mexico across a series of seismic data profiles indicating rapid transitions between the presence of methane hydrates and vertical gas flux. Vertical profiles of dissolved sulfate, chloride, calcium, magnesium, and dissolved inorganic carbon (DIC concentrations in porewaters, headspace methane, and solid phase carbonate concentrations were measured at each core location to investigate the cycling of methane-derived carbon in shallow sediments overlying the hydrate bearing strata. When integrated with stable carbon isotope ratios of DIC, geochemical results suggest a significant fraction of the methane flux at this site is cycled into the inorganic carbon pool. The incorporation of methane-derived carbon into dissolved and solid inorganic carbon phases represents a significant sink in local carbon cycling and plays a role in regulating the flux of methane to the overlying water column at Alaminos Canyon. Targeted, high-resolution geochemical characterization of the biogeochemical cycling of methane-derived carbon in shallow sediments overlying hydrate bearing strata like those in Alaminos Canyon is critical to quantifying methane flux and estimating methane hydrate distributions in gas hydrate bearing marine sediments.

A Novel Study of Methane-Rich Gas Reforming to Syngas and Its Kinetics over Semicoke Catalyst

Directory of Open Access Journals (Sweden)

Guojie Zhang

2014-01-01

Full Text Available A small-size gasification unit is improved through process optimization to simulate industrial United Gas Improvement Company gasification. It finds that the reaction temperature has important impacts on semicoke catalyzed methane gas mixture. The addition of water vapor can enhance the catalytic activity of reforming, which is due to the fact that addition of water vapor not only removes carbon deposit produced in the reforming and gasification reaction processes, but also participates in gasification reaction with semicoke to generate some active oxygen-containing functional groups. The active oxygen-containing functional groups provide active sites for carbon dioxide reforming of methane, promoting the reforming reaction. It also finds that the addition of different proportions of methane-rich gas can yield synthesis gas with different H2/CO ratio. The kinetics study shows that the semicoke can reduce the activation energy of the reforming reaction and promote the occurrence of the reforming reaction. The kinetics model of methane reforming under the conditions of steam gasification over semicoke is as follows: k-=5.02×103·pCH40.71·pH20.26·exp(−74200/RT.

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.

Effect of concentrate feed level on methane emissions from grazing dairy cows.

Science.gov (United States)

Jiao, H P; Dale, A J; Carson, A F; Murray, S; Gordon, A W; Ferris, C P

2014-11-01

Although the effect of nutrition on enteric methane (CH4) emissions from confined dairy cattle has been extensively examined, less information is available on factors influencing CH4 emissions from grazing dairy cattle. In the present experiment, 40 Holstein-Friesian dairy cows (12 primiparous and 28 multiparous) were used to examine the effect of concentrate feed level (2.0, 4.0, 6.0, and 8.0 kg/cow per day; fresh basis) on enteric CH4 emissions from cows grazing perennial ryegrass-based swards (10 cows per treatment). Methane emissions were measured on 4 occasions during the grazing period (one 4-d measurement period and three 5-d measurement periods) using the sulfur hexafluoride technique. Milk yield, liveweight, and milk composition for each cow was recorded daily during each CH4 measurement period, whereas daily herbage dry matter intake (DMI) was estimated for each cow from performance data, using the back-calculation approach. Total DMI, milk yield, and energy-corrected milk (ECM) yield increased with increasing concentrate feed level. Within each of the 4 measurement periods, daily CH4 production (g/d) was unaffected by concentrate level, whereas CH4/DMI decreased with increasing concentrate feed level in period 4, and CH4/ECM yield decreased with increasing concentrate feed level in periods 2 and 4. When emissions data were combined across all 4 measurement periods, concentrate feed level (2.0, 4.0, 6.0, and 8.0 kg/d; fresh basis) had no effect on daily CH4 emissions (287, 273, 272, and 277 g/d, respectively), whereas CH4/DMI (20.0, 19.3, 17.7, and 18.1g/kg, respectively) and CH4-E/gross energy intake (0.059, 0.057, 0.053, and 0.054, respectively) decreased with increasing concentrate feed levels. A range of prediction equations for CH4 emissions were developed using liveweight, DMI, ECM yield, and energy intake, with the strongest relationship found between ECM yield and CH4/ECM yield (coefficient of determination = 0.50). These results demonstrate that

Effect of unconventional oilseeds (safflower, poppy, hemp, camelina) on in vitro ruminal methane production and fermentation.

Science.gov (United States)

Wang, Shaopu; Kreuzer, Michael; Braun, Ueli; Schwarm, Angela

2017-08-01

Dietary supplementation with oilseeds can reduce methane emission in ruminants, but only a few common seeds have been tested so far. This study tested safflower (Carthamus tinctorius), poppy (Papaver somniferum), hemp (Cannabis sativa), and camelina (Camelina sativa) seeds in vitro using coconut (Cocos nucifera) oil and linseed (Linum usitatissimum) as positive controls. All the tested oilseeds suppressed methane yield (mL g -1 dry matter, up to 21%) compared to the non-supplemented control when provided at 70 g oil kg -1 dry matter, and they were as effective as coconut oil. Safflower and hemp were more effective than linseed (21% and 18% vs. 10%), whereas the effects of poppy and camelina were similar to linseed. When methane was related to digestible organic matter, only hemp and safflower seeds and coconut oil were effective compared to the non-supplemented control (up to 11%). The level of methanogenesis and the ratios of either the n-6:n-3 fatty acids or C 18 :2 :C 18 :3 in the seed lipids were not related. Unconventional oilseeds widen the spectrum of oilseeds that can be used in dietary methane mitigation. In vivo confirmation of their methane mitigating effect is still needed, and their effects on animal performance still must be determined. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Anaerobic methane oxidation coupled to denitrification is the dominant methane sink in a deep lake

Science.gov (United States)

Deutzmann, Joerg S.; Stief, Peter; Brandes, Josephin; Schink, Bernhard

2014-01-01

Anaerobic methane oxidation coupled to denitrification, also known as “nitrate/nitrite-dependent anaerobic methane oxidation” (n-damo), was discovered in 2006. Since then, only a few studies have identified this process and the associated microorganisms in natural environments. In aquatic sediments, the close proximity of oxygen- and nitrate-consumption zones can mask n-damo as aerobic methane oxidation. We therefore investigated the vertical distribution and the abundance of denitrifying methanotrophs related to Candidatus Methylomirabilis oxyfera with cultivation-independent molecular techniques in the sediments of Lake Constance. Additionally, the vertical distribution of methane oxidation and nitrate consumption zones was inferred from high-resolution microsensor profiles in undisturbed sediment cores. M. oxyfera-like bacteria were virtually absent at shallow-water sites (littoral sediment) and were very abundant at deep-water sites (profundal sediment). In profundal sediment, the vertical distribution of M. oxyfera-like bacteria showed a distinct peak in anoxic layers that coincided with the zone of methane oxidation and nitrate consumption, a strong indication for n-damo carried out by M. oxyfera-like bacteria. Both potential n-damo rates calculated from cell densities (660–4,890 µmol CH4⋅m−2⋅d−1) and actual rates calculated from microsensor profiles (31–437 µmol CH4⋅m−2⋅d−1) were sufficiently high to prevent methane release from profundal sediment solely by this process. Additionally, when nitrate was added to sediment cores exposed to anoxic conditions, the n-damo zone reestablished well below the sediment surface, completely preventing methane release from the sediment. We conclude that the previously overlooked n-damo process can be the major methane sink in stable freshwater environments if nitrate is available in anoxic zones. PMID:25472842

Anaerobic methane oxidation coupled to denitrification is the dominant methane sink in a deep lake.

Science.gov (United States)

Deutzmann, Joerg S; Stief, Peter; Brandes, Josephin; Schink, Bernhard

2014-12-23

Anaerobic methane oxidation coupled to denitrification, also known as "nitrate/nitrite-dependent anaerobic methane oxidation" (n-damo), was discovered in 2006. Since then, only a few studies have identified this process and the associated microorganisms in natural environments. In aquatic sediments, the close proximity of oxygen- and nitrate-consumption zones can mask n-damo as aerobic methane oxidation. We therefore investigated the vertical distribution and the abundance of denitrifying methanotrophs related to Candidatus Methylomirabilis oxyfera with cultivation-independent molecular techniques in the sediments of Lake Constance. Additionally, the vertical distribution of methane oxidation and nitrate consumption zones was inferred from high-resolution microsensor profiles in undisturbed sediment cores. M. oxyfera-like bacteria were virtually absent at shallow-water sites (littoral sediment) and were very abundant at deep-water sites (profundal sediment). In profundal sediment, the vertical distribution of M. oxyfera-like bacteria showed a distinct peak in anoxic layers that coincided with the zone of methane oxidation and nitrate consumption, a strong indication for n-damo carried out by M. oxyfera-like bacteria. Both potential n-damo rates calculated from cell densities (660-4,890 µmol CH4⋅m(-2)⋅d(-1)) and actual rates calculated from microsensor profiles (31-437 µmol CH4⋅m(-2)⋅d(-1)) were sufficiently high to prevent methane release from profundal sediment solely by this process. Additionally, when nitrate was added to sediment cores exposed to anoxic conditions, the n-damo zone reestablished well below the sediment surface, completely preventing methane release from the sediment. We conclude that the previously overlooked n-damo process can be the major methane sink in stable freshwater environments if nitrate is available in anoxic zones.

46 CFR 154.703 - Methane (LNG).

Science.gov (United States)

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Methane (LNG). 154.703 Section 154.703 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SAFETY STANDARDS FOR... and Temperature Control § 154.703 Methane (LNG). Unless a cargo tank carrying methane (LNG) can...

Prediction of Local Ultimate Strain and Toughness of Trabecular Bone Tissue by Raman Material Composition Analysis

Directory of Open Access Journals (Sweden)

Roberto Carretta

2015-01-01

Full Text Available Clinical studies indicate that bone mineral density correlates with fracture risk at the population level but does not correlate with individual fracture risk well. Current research aims to better understand the failure mechanism of bone and to identify key determinants of bone quality, thus improving fracture risk prediction. To get a better understanding of bone strength, it is important to analyze tissue-level properties not influenced by macro- or microarchitectural factors. The aim of this pilot study was to identify whether and to what extent material properties are correlated with mechanical properties at the tissue level. The influence of macro- or microarchitectural factors was excluded by testing individual trabeculae. Previously reported data of mechanical parameters measured in single trabeculae under tension and bending and its compositional properties measured by Raman spectroscopy was evaluated. Linear and multivariate regressions show that bone matrix quality but not quantity was significantly and independently correlated with the tissue-level ultimate strain and postyield work (r=0.65–0.94. Principal component analysis extracted three independent components explaining 86% of the total variance, representing elastic, yield, and ultimate components according to the included mechanical parameters. Some matrix parameters were both included in the ultimate component, indicating that the variation in ultimate strain and postyield work could be largely explained by Raman-derived compositional parameters.

Ultimate - a new generation of gasoline and diesel fuels; Ultimate - eine neue Generation von Otto- und Dieselkraftstoffen

Energy Technology Data Exchange (ETDEWEB)

Strempel, G. [Aral Forschung/Global Fuels Technology, Bochum (Germany); Beckwith, P. [BP Fuels Management Group, Pangbourne (United Kingdom); Froehling, J. [Aral Forschung, Bochum (Germany). Labor/Analytik; Baron, U. [Aral Forschung, Bochum (Germany). Motor- und Fahrzeuglaboratorium; Sauermann, P.; Balfanz, U. [Aral Forschung, Bochum (Germany). Produktentwicklung; Doermer, W. [Aral Forschung, Bochum (Germany). Produktqualitaet

2005-06-01

With the launch of Ultimate 100 gasoline and Ultimate Diesel, motorists in Germany now have the opportunity to choose new advanced performance fuels designed to get the very best from their engines. This article gives details of the technical development behind these fuels, their wide range of benefits, and how it is possible to manufacture fuels which meet the considerable technical challenge of achieving both more performance and less pollution. (orig.)

Supported Catalysts for CO2 Methanation: A Review

Directory of Open Access Journals (Sweden)

Patrizia Frontera

2017-02-01

Full Text Available CO2 methanation is a well-known reaction that is of interest as a capture and storage (CCS process and as a renewable energy storage system based on a power-to-gas conversion process by substitute or synthetic natural gas (SNG production. Integrating water electrolysis and CO2 methanation is a highly effective way to store energy produced by renewables sources. The conversion of electricity into methane takes place via two steps: hydrogen is produced by electrolysis and converted to methane by CO2 methanation. The effectiveness and efficiency of power-to-gas plants strongly depend on the CO2 methanation process. For this reason, research on CO2 methanation has intensified over the last 10 years. The rise of active, selective, and stable catalysts is the core of the CO2 methanation process. Novel, heterogeneous catalysts have been tested and tuned such that the CO2 methanation process increases their productivity. The present work aims to give a critical overview of CO2 methanation catalyst production and research carried out in the last 50 years. The fundamentals of reaction mechanism, catalyst deactivation, and catalyst promoters, as well as a discussion of current and future developments in CO2 methanation, are also included.

Methane emission from natural wetlands: interplay between emergent macrophytes and soil microbial processes. A mini-review

Science.gov (United States)

Laanbroek, Hendrikus J.

2010-01-01

Background According to the Intergovernmental Panel on Climate Change (IPCC) 2007, natural wetlands contribute 20–39 % to the global emission of methane. The range in the estimated percentage of the contribution of these systems to the total release of this greenhouse gas is large due to differences in the nature of the emitting vegetation including the soil microbiota that interfere with the production and consumption of methane. Scope Methane is a dominant end-product of anaerobic mineralization processes. When all electron acceptors except carbon dioxide are used by the microbial community, methanogenesis is the ultimate pathway to mineralize organic carbon compounds. Emergent wetland plants play an important role in the emission of methane to the atmosphere. They produce the carbon necessary for the production of methane, but also facilitate the release of methane by the possession of a system of interconnected internal gas lacunas. Aquatic macrophytes are commonly adapted to oxygen-limited conditions as they prevail in flooded or waterlogged soils. By this system, oxygen is transported to the underground parts of the plants. Part of the oxygen transported downwards is released in the root zone, where it sustains a number of beneficial oxidation processes. Through the pores from which oxygen escapes from the plant into the root zone, methane can enter the plant aerenchyma system and subsequently be emitted into the atmosphere. Part of the oxygen released into the root zone can be used to oxidize methane before it enters the atmosphere. However, the oxygen can also be used to regenerate alternative electron acceptors. The continuous supply of alternative electron acceptors will diminish the role of methanogenesis in the anaerobic mineralization processes in the root zone and therefore repress the production and emission of methane. The role of alternative element cycles in the inhibition of methanogenesis is discussed. Conclusions The role of the nitrogen

Methane flux from boreal peatlands

International Nuclear Information System (INIS)

Crill, P.; Bartlett, K.; Roulet, N.

1992-01-01

The peatlands in the boreal zone (roughly 45 deg - 60 degN) store a significant reservoir of carbon, much of which is potentially available for exchange with the atmosphere. The anaerobic conditions that cause these soils to accumulate carbon also makes wet, boreal peatlands significant sources of methane to the global troposphere. It is estimated that boreal wetlands contribute approximately 19.5 Tg methane per year. The data available on the magnitude of boreal methane emissions have rapidly accumulated in the past twenty years. This paper offers a short review of the flux measured (with range roughly 1 - 2000 mg methane/m2d), considers environmental controls of the flux and briefly discusses how climate change might affect future fluxes

Integration of Methane Steam Reforming and Water Gas Shift Reaction in a Pd/Au/Pd-Based Catalytic Membrane Reactor for Process Intensification.

Science.gov (United States)

Castro-Dominguez, Bernardo; Mardilovich, Ivan P; Ma, Liang-Chih; Ma, Rui; Dixon, Anthony G; Kazantzis, Nikolaos K; Ma, Yi Hua

2016-09-19

Palladium-based catalytic membrane reactors (CMRs) effectively remove H₂ to induce higher conversions in methane steam reforming (MSR) and water-gas-shift reactions (WGS). Within such a context, this work evaluates the technical performance of a novel CMR, which utilizes two catalysts in series, rather than one. In the process system under consideration, the first catalyst, confined within the shell side of the reactor, reforms methane with water yielding H₂, CO and CO₂. After reforming is completed, a second catalyst, positioned in series, reacts with CO and water through the WGS reaction yielding pure H₂O, CO₂ and H₂. A tubular composite asymmetric Pd/Au/Pd membrane is situated throughout the reactor to continuously remove the produced H₂ and induce higher methane and CO conversions while yielding ultrapure H₂ and compressed CO₂ ready for dehydration. Experimental results involving (i) a conventional packed bed reactor packed (PBR) for MSR, (ii) a PBR with five layers of two catalysts in series and (iii) a CMR with two layers of two catalysts in series are comparatively assessed and thoroughly characterized. Furthermore, a comprehensive 2D computational fluid dynamics (CFD) model was developed to explore further the features of the proposed configuration. The reaction was studied at different process intensification-relevant conditions, such as space velocities, temperatures, pressures and initial feed gas composition. Finally, it is demonstrated that the above CMR module, which was operated for 600 h, displays quite high H₂ permeance and purity, high CH₄ conversion levels and reduced CO yields.

Integration of Methane Steam Reforming and Water Gas Shift Reaction in a Pd/Au/Pd-Based Catalytic Membrane Reactor for Process Intensification

Directory of Open Access Journals (Sweden)

Bernardo Castro-Dominguez

2016-09-01

Full Text Available Palladium-based catalytic membrane reactors (CMRs effectively remove H2 to induce higher conversions in methane steam reforming (MSR and water-gas-shift reactions (WGS. Within such a context, this work evaluates the technical performance of a novel CMR, which utilizes two catalysts in series, rather than one. In the process system under consideration, the first catalyst, confined within the shell side of the reactor, reforms methane with water yielding H2, CO and CO2. After reforming is completed, a second catalyst, positioned in series, reacts with CO and water through the WGS reaction yielding pure H2O, CO2 and H2. A tubular composite asymmetric Pd/Au/Pd membrane is situated throughout the reactor to continuously remove the produced H2 and induce higher methane and CO conversions while yielding ultrapure H2 and compressed CO2 ready for dehydration. Experimental results involving (i a conventional packed bed reactor packed (PBR for MSR, (ii a PBR with five layers of two catalysts in series and (iii a CMR with two layers of two catalysts in series are comparatively assessed and thoroughly characterized. Furthermore, a comprehensive 2D computational fluid dynamics (CFD model was developed to explore further the features of the proposed configuration. The reaction was studied at different process intensification-relevant conditions, such as space velocities, temperatures, pressures and initial feed gas composition. Finally, it is demonstrated that the above CMR module, which was operated for 600 h, displays quite high H2 permeance and purity, high CH4 conversion levels and reduced CO yields.

Biochemically enhanced methane production from coal

Science.gov (United States)

Opara, Aleksandra

For many years, biogas was connected mostly with the organic matter decomposition in shallow sediments (e.g., wetlands, landfill gas, etc.). Recently, it has been realized that biogenic methane production is ongoing in many hydrocarbon reservoirs. This research examined microbial methane and carbon dioxide generation from coal. As original contributions methane production from various coal materials was examined in classical and electro-biochemical bench-scale reactors using unique, developed facultative microbial consortia that generate methane under anaerobic conditions. Facultative methanogenic populations are important as all known methanogens are strict anaerobes and their application outside laboratory would be problematic. Additional testing examined the influence of environmental conditions, such as pH, salinity, and nutrient amendments on methane and carbon dioxide generation. In 44-day ex-situ bench-scale batch bioreactor tests, up to 300,000 and 250,000 ppm methane was generated from bituminous coal and bituminous coal waste respectively, a significant improvement over 20-40 ppm methane generated from control samples. Chemical degradation of complex hydrocarbons using environmentally benign reagents, prior to microbial biodegradation and methanogenesis, resulted in dissolution of up to 5% bituminous coal and bituminous coal waste and up to 25% lignite in samples tested. Research results confirm that coal waste may be a significant underutilized resource that could be converted to useful fuel. Rapid acidification of lignite samples resulted in low pH (below 4.0), regardless of chemical pretreatment applied, and did not generate significant methane amounts. These results confirmed the importance of monitoring and adjusting in situ and ex situ environmental conditions during methane production. A patented Electro-Biochemical Reactor technology was used to supply electrons and electron acceptor environments, but appeared to influence methane generation in a

Methane and Climate Change

NARCIS (Netherlands)

Reay, D.; Smith, P.; Amstel, van A.R.

2010-01-01

Methane is a powerful greenhouse gas and is estimated to be responsible for approximately one-fifth of man-made global warming. Per kilogram, it is 25 times more powerful than carbon dioxide over a 100-year time horizon -- and global warming is likely to enhance methane release from a number of

Effects of forage type and extruded linseed supplementation on methane production and milk fatty acid composition of lactating dairy cows.

Science.gov (United States)

Livingstone, K M; Humphries, D J; Kirton, P; Kliem, K E; Givens, D I; Reynolds, C K

2015-06-01

Replacing dietary grass silage (GS) with maize silage (MS) and dietary fat supplements may reduce milk concentration of specific saturated fatty acids (SFA) and can reduce methane production by dairy cows. The present study investigated the effect of feeding an extruded linseed supplement on milk fatty acid (FA) composition and methane production of lactating dairy cows, and whether basal forage type, in diets formulated for similar neutral detergent fiber and starch, altered the response to the extruded linseed supplement. Four mid-lactation Holstein-Friesian cows were fed diets as total mixed rations, containing either high proportions of MS or GS, both with or without extruded linseed supplement, in a 4×4 Latin square design experiment with 28-d periods. Diets contained 500 g of forage/kg of dry matter (DM) containing MS and GS in proportions (DM basis) of either 75:25 or 25:75 for high MS or high GS diets, respectively. Extruded linseed supplement (275 g/kg ether extract, DM basis) was included in treatment diets at 50 g/kg of DM. Milk yields, DM intake, milk composition, and methane production were measured at the end of each experimental period when cows were housed in respiration chambers. Whereas DM intake was higher for the MS-based diet, forage type and extruded linseed had no significant effect on milk yield, milk fat, protein, or lactose concentration, methane production, or methane per kilogram of DM intake or milk yield. Total milk fat SFA concentrations were lower with MS compared with GS-based diets (65.4 vs. 68.4 g/100 g of FA, respectively) and with extruded linseed compared with no extruded linseed (65.2 vs. 68.6 g/100 g of FA, respectively), and these effects were additive. Concentrations of total trans FA were higher with MS compared with GS-based diets (7.0 vs. 5.4 g/100 g of FA, respectively) and when extruded linseed was fed (6.8 vs. 5. 6g/100 g of FA, respectively). Total n-3 FA were higher when extruded linseed was fed compared with no

Autothermal catalytic pyrolysis of methane as a new route to hydrogen production with reduced CO{sub 2} emissions

Energy Technology Data Exchange (ETDEWEB)

Muradov, Nazim; Smith, Franklyn; Huang, Cunping; T-Raissi, Ali [Florida Solar Energy Center, University of Central Florida, Cocoa, FL 32922 (United States)

2006-08-15

Hydrogen production plants are among major sources of CO{sub 2} emissions into the atmosphere. The objective of this paper is to explore new routes to hydrogen production from natural gas (or methane) with drastically reduced CO{sub 2} emissions. One approach analyzed in this paper is based on thermocatalytic decomposition (or pyrolysis) of methane into hydrogen gas and elemental carbon over carbon-based catalysts. Several heat input options to the endothermic process are discussed in the paper. The authors conduct thermodynamic analysis of methane decomposition in the presence of small amounts of oxygen in an autothermal (or thermo-neutral) regime using AspenPlus(TM) chemical process simulator. Methane conversion, products yield, effluent gas composition, process enthalpy flows as a function of temperature, pressure and O{sub 2}/CH{sub 4} ratio has been determined. CO{sub 2} emissions (per m{sup 3} of H{sub 2} produced) from the process could potentially be a factor of 3-5 less than from conventional hydrogen production processes. Oxygen-assisted decomposition of methane over activated carbon (AC) and AC-supported iron catalysts over wide range of temperatures and O{sub 2}/CH{sub 4} ratios was experimentally verified. Problems associated with the catalyst deactivation and the effect of iron doping on the catalyst stability are discussed. (author)

Small Molecule Catalysts for Harvesting Methane Gas

Energy Technology Data Exchange (ETDEWEB)

Baker, S. E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Ceron-Hernandez, M. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Oakdale, J. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Lau, E. Y. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2016-12-06

As the average temperature of the earth increases the impact of these changes are becoming apparent. One of the most dramatic changes to the environment is the melting of arctic permafrost. The disappearance of the permafrost has resulted in release of streams of methane that was trapped in remote areas as gas hydrates in ice. Additionally, the use of fracking has also increased emission of methane. Currently, the methane is either lost to the atmosphere or flared. If these streams of methane could be brought to market, this would be an abundant source of revenue. A cheap conversion of gaseous methane to a more convenient form for transport would be necessary to economical. Conversion of methane is a difficult reaction since the C-H bond is very stable (104 kcal/mole). At the industrial scale, the Fischer-Tropsch reaction can be used to convert gaseous methane to liquid methanol but is this method is impractical for these streams that have low pressures and are located in remote areas. Additionally, the Fischer-Tropsch reaction results in over oxidation of the methane leading to many products that would need to be separated.

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

Constraining the relationships between anaerobic oxidation of methane and sulfate reduction under in situ methane concentrations

Science.gov (United States)

Zhuang, G.; Wegener, G.; Joye, S. B.

2017-12-01

The anaerobic oxidation of methane (AOM) is an important microbial metabolism in the global carbon cycle. In marine methane seeps sediment, this process is mediated by syntrophic consortium that includes anaerobic methanotrophic archaea (ANME) and sulfate-reducing bacteria (SRB). Stoichiometrically in AOM methane oxidation should be coupled to sulfate reduction (SR) in a 1:1 ratio. However, weak coupling of AOM and SR in seep sediments was frequently observed from the ex situ rate measurements, and the metabolic dynamics of AOM and SR under in situ conditions remain poorly understood. Here we investigated the metabolic activity of AOM and SR with radiotracers by restoring in situ methane concentrations under pressure to constrain the in situ relationships between AOM and SR in the cold seep sediments of Gulf of Mexico as well as the sediment-free AOM enrichments cultivated from cold seep of Italian Island Elba or hydrothermal vent of Guaymas Basin5. Surprisingly, we found that AOM rates strongly exceeded those of SR when high pressures and methane concentrations were applied at seep sites of GC600 and GC767 in Gulf of Mexico. With the addition of molybdate, SR was inhibited but AOM was not affected, suggesting the potential coupling of AOM with other terminal processes. Amendments of nitrate, iron, manganese and AQDS to the SR-inhibited slurries did not stimulate or inhibit the AOM activity, indicating either those electron acceptors were not limiting for AOM in the sediments or AOM was coupled to other process (e.g., organic matter). In the ANME enrichments, higher AOM rates were also observed with the addition of high concentrations of methane (10mM and 50 mM). The tracer transfer of CO2 to methane, i.e., the back reaction of AOM, increased with increasing methane concentrations and accounted for 1%-5% of the AOM rates. AOM rates at 10 mM and 50 mM methane concentration were much higher than the SR rates, suggesting those two processes were not tightly coupled

Two-Dimensional Layered Double Hydroxides for Reactions of Methanation and Methane Reforming in C1 Chemistry.

Science.gov (United States)

Li, Panpan; Yu, Feng; Altaf, Naveed; Zhu, Mingyuan; Li, Jiangbing; Dai, Bin; Wang, Qiang

2018-01-31

CH₄ as the paramount ingredient of natural gas plays an eminent role in C1 chemistry. CH₄ catalytically converted to syngas is a significant route to transmute methane into high value-added chemicals. Moreover, the CO/CO₂ methanation reaction is one of the potent technologies for CO₂ valorization and the coal-derived natural gas production process. Due to the high thermal stability and high extent of dispersion of metallic particles, two-dimensional mixed metal oxides through calcined layered double hydroxides (LDHs) precursors are considered as the suitable supports or catalysts for both the reaction of methanation and methane reforming. The LDHs displayed compositional flexibility, small crystal sizes, high surface area and excellent basic properties. In this paper, we review previous works of LDHs applied in the reaction of both methanation and methane reforming, focus on the LDH-derived catalysts, which exhibit better catalytic performance and thermal stability than conventional catalysts prepared by impregnation method and also discuss the anti-coke ability and anti-sintering ability of LDH-derived catalysts. We believe that LDH-derived catalysts are promising materials in the heterogeneous catalytic field and provide new insight for the design of advance LDH-derived catalysts worthy of future research.

Production of CO-rich Hydrogen Gas from Methane Dry Reforming over Co/CeO2 Catalyst

Directory of Open Access Journals (Sweden)

Bamidele V. Ayodele

2016-08-01

Full Text Available Production of CO-rich hydrogen gas from methane dry reforming was investigated over CeO2-supported Co catalyst. The catalyst was synthesized by wet impregnation and subsequently characterized by field emission scanning electron microscope (FESEM, energy dispersion X-ray spectroscopy (EDX, liquid N2 adsorption-desorption, X-ray diffraction (XRD, Fourier transform infrared spectroscopy (FTIR and thermogravimetric analysis (TGA for the structure, surface and thermal properties. The catalytic activity test of the Co/CeO2 was investigated between 923-1023 K under reaction conditions in a stainless steel fixed bed reactor. The composition of the products (CO2 and H2 from the methane dry reforming reaction was measured by gas chromatography (GC coupled with thermal conductivity detector (TCD. The effects of feed ratios and reaction temperatures were investigated on the catalytic activity toward product selectivity, yield, and syngas ratio. Significantly, the selectivity and yield of both H2 and CO increases with feed ratio and temperature. However, the catalyst shows higher activity towards CO selectivity. The highest H2 and CO selectivity of 19.56% and 20.95% respectively were obtained at 1023 K while the highest yield of 41.98% and 38.05% were recorded for H2 and CO under the same condition. Copyright © 2016 BCREC GROUP. All rights reserved Received: 21st January 2016; Revised: 23rd February 2016; Accepted: 23rd February 2016 How to Cite: Ayodele, B.V., Khan, M.R., Cheng, C. K. (2016. Production of CO-rich Hydrogen Gas from Methane Dry Reforming over Co/CeO2 Catalyst. Bulletin of Chemical Reaction Engineering & Catalysis, 11 (2: 210-219 (doi:10.9767/bcrec.11.2.552.210-219 Permalink/DOI: http://dx.doi.org/10.9767/bcrec.11.2.552.210-219

Anaerobic methane oxidation coupled to denitrification is the dominant methane sink in a deep lake

DEFF Research Database (Denmark)

Deutzmann, Joerg S.; Stief, Peter; Brandes, Josephin

2014-01-01

Anaerobic methane oxidation coupled to denitrification, also known as “nitrate/nitrite-dependent anaerobic methane oxidation” (n-damo), was discovered in 2006. Since then, only a few studies have identified this process and the associated microorganisms in natural environments. In aquatic sediments......, the close proximity of oxygen- and nitrate-consumption zones can mask n-damo as aerobic methane oxidation. We therefore investigated the vertical distribution and the abundance of denitrifying methanotrophs related to Candidatus Methylomirabilis oxyfera with cultivation-independent molecular techniques...... in the sediments of Lake Constance. Additionally, the vertical distribution of methane oxidation and nitrate consumption zones was inferred from high-resolution microsensor profiles in undisturbed sediment cores. M. oxyfera-like bacteria were virtually absent at shallow-water sites (littoral sediment) and were...

Enteric Methane Emission from Pigs

DEFF Research Database (Denmark)

Jørgensen, Henry; Theil, Peter Kappel; Knudsen, Knud Erik Bach

2011-01-01

per kg meat produced is increased (Fernández et al. 1983; Lekule et al. 1990). The present chapter will summarise our current knowledge concerning dietary and enteric fermentation that may influence the methane (CH4) emission in pigs. Enteric fermentation is the digestive process by which.......3 % of the worlds pig population. The main number of pigs is in Asia (59.6 %) where the main pig population stay in China (47.8 % of the worlds pig population). The objective of the chapter is therefore: To obtain a general overview of the pigs’ contribution to methane emission. Where is the pigs’ enteric gas...... produced and how is it measured. The variation in methane emission and factors affecting the emission. Possibility for reducing the enteric methane emission and the consequences....

Milk metabolome relates enteric methane emission to milk synthesis and energy metabolism pathways.

Science.gov (United States)

Antunes-Fernandes, E C; van Gastelen, S; Dijkstra, J; Hettinga, K A; Vervoort, J

2016-08-01

Methane (CH4) emission of dairy cows contributes significantly to the carbon footprint of the dairy chain; therefore, a better understanding of CH4 formation is urgently needed. The present study explored the milk metabolome by gas chromatography-mass spectrometry (milk volatile metabolites) and nuclear magnetic resonance (milk nonvolatile metabolites) to better understand the biological pathways involved in CH4 emission in dairy cattle. Data were used from a randomized block design experiment with 32 multiparous Holstein-Friesian cows and 4 diets. All diets had a roughage:concentrate ratio of 80:20 (dry matter basis) and the roughage was grass silage (GS), corn silage (CS), or a mixture of both (67% GS, 33% CS; 33% GS, 67% CS). Methane emission was measured in climate respiration chambers and expressed as CH4 yield (per unit of dry matter intake) and CH4 intensity (per unit of fat- and protein-corrected milk; FPCM). No volatile or nonvolatile metabolite was positively related to CH4 yield, and acetone (measured as a volatile and as a nonvolatile metabolite) was negatively related to CH4 yield. The volatile metabolites 1-heptanol-decanol, 3-nonanone, ethanol, and tetrahydrofuran were positively related to CH4 intensity. None of the volatile metabolites was negatively related to CH4 intensity. The nonvolatile metabolites acetoacetate, creatinine, ethanol, formate, methylmalonate, and N-acetylsugar A were positively related to CH4 intensity, and uridine diphosphate (UDP)-hexose B and citrate were negatively related to CH4 intensity. Several volatile and nonvolatile metabolites that were correlated with CH4 intensity also were correlated with FPCM and not significantly related to CH4 intensity anymore when FPCM was included as covariate. This suggests that changes in these milk metabolites may be related to changes in milk yield or metabolic processes involved in milk synthesis. The UDP-hexose B was correlated with FPCM, whereas citrate was not. Both metabolites were

Agricultural methanization

International Nuclear Information System (INIS)

2011-01-01

After having briefly outlined the interest of the development of methanization of agricultural by-products in the context of struggle against climate change, and noticed that France is only now developing this sector as some other countries already did, this publication describes the methanization process also called anaerobic digestion, which produces a digestate and biogas. Advantages for the agriculture sector are outlined, as well as drawbacks and recommendations (required specific technical abilities, an attention to the use of energetic crops, an improved economic balance which still depends on public subsidies, competition in the field of waste processing). Actions undertaken by the ADEME are briefly evoked

Anaerobic co-digestion of food waste and septage – A waste to energy project in Nashik city

Directory of Open Access Journals (Sweden)

Meghanath Prabhu

2015-04-01

Full Text Available The samples for food waste (FW and septage were collected from six localities of Nashik city. Physical and chemical characterizations of the wastes were carried out. A Biomethanation potential (BMP assay was developed to determine the ultimate biodegradability and associated methane yield during the anaerobic methanogenic fermentation of organic substrates. BMP assays of individual substrate, FW and septage were carried out by taking into account the volatile solids/total solids (VS/TS ratio of each while keeping the inoculum’s VS constant. BMP of FW and septage mixture was carried out in different ratios (1:1, 1.5:1, 2:1, 1:1.5 and 1:2 to find the optimum mixing ratio for maximum biogas production. The average methane yield for different locality FW was found to be 503±17.6 ml/g VS and for septage it was 56 ±10.8 ml/g VS. Based on the above results, the total biogas yield and total methane yield for 10 tons of FW would be 2178 m3/d and 1306 m3/d respectively. The total biogas yield and total methane yield for 20 m3 of septage would be 65m3/d and 39m3/d respectively. From our co-digestion studies we also conclude that the mixture of FW to septage at 1:2 ratio gives 2896 m3/day of biogas. The role of septage is to provide essential trace elements that are required for methanogens.

Low-Altitude Aerial Methane Concentration Mapping

Directory of Open Access Journals (Sweden)

Bara J. Emran

2017-08-01

Full Text Available Detection of leaks of fugitive greenhouse gases (GHGs from landfills and natural gas infrastructure is critical for not only their safe operation but also for protecting the environment. Current inspection practices involve moving a methane detector within the target area by a person or vehicle. This procedure is dangerous, time consuming, labor intensive and above all unavailable when access to the desired area is limited. Remote sensing by an unmanned aerial vehicle (UAV equipped with a methane detector is a cost-effective and fast method for methane detection and monitoring, especially for vast and remote areas. This paper describes the integration of an off-the-shelf laser-based methane detector into a multi-rotor UAV and demonstrates its efficacy in generating an aerial methane concentration map of a landfill. The UAV flies a preset flight path measuring methane concentrations in a vertical air column between the UAV and the ground surface. Measurements were taken at 10 Hz giving a typical distance between measurements of 0.2 m when flying at 2 m/s. The UAV was set to fly at 25 to 30 m above the ground. We conclude that besides its utility in landfill monitoring, the proposed method is ready for other environmental applications as well as the inspection of natural gas infrastructure that can release methane with much higher concentrations.

High-solid anaerobic digestion of corn straw for methane production and pretreatment of bio-briquette.

Science.gov (United States)

Li, Yeqing; Yan, Fang; Li, Tao; Zhou, Ying; Jiang, Hao; Qian, Mingyu; Xu, Quan

2018-02-01

In this study, an integrated process was developed to produce methane and high-quality bio-briquette (BB) using corn straw (CS) through high-solid anaerobic digestion (HS-AD). CS was anaerobic digested by using a leach bed reactor at four leachate recirculation strategies. After digesting for 28 days, highest methane yield of 179.6 mL/g-VS, which was corresponded to energy production of 5.55 MJ/kg-CS, was obtained at a higher initial recirculation rate of 32 L-leachate per day. Compared with bio-briquette manufactured from raw CS and lignite, the compressive, immersion and falling strength properties of bio-briquette made from AD-treated CS (solid digestate) and lignite were significantly improved. A preferred BB can be obtained with side compressive strength of 863.8 ± 10.8 N and calorific value of 20.21 MJ/kg-BB. The finding of this study indicated that the integrated process could be an alternative way to produce methane and high-quality BB with CS. Copyright © 2017 Elsevier Ltd. All rights reserved.

Methane hydroxylation: a biomimetic approach

International Nuclear Information System (INIS)

Shilov, Aleksandr E; Shteinman, Al'bert A

2012-01-01

The review addresses direct methane oxidation — an important fundamental problem, which has attracted much attention of researchers in recent years. Analysis of the available results on biomimetic and bio-inspired methane oxygenation has demonstrated that assimilating of the experience of Nature on oxidation of methane and other alkanes significantly enriches the arsenal of chemistry and can radically change the character of the entire chemical production, as well as enables the solution of many material, energetic and environmental problems. The bibliography includes 310 references.

Microbial methane from in situ biodegradation of coal and shale: A review and reevaluation of hydrogen and carbon isotope signatures

Science.gov (United States)

Vinson, David S.; Blair, Neal E.; Martini, Anna M.; Larter, Steve; Orem, William H.; McIntosh, Jennifer C.

2017-01-01

Stable carbon and hydrogen isotope signatures of methane, water, and inorganic carbon are widely utilized in natural gas systems for distinguishing microbial and thermogenic methane and for delineating methanogenic pathways (acetoclastic, hydrogenotrophic, and/or methylotrophic methanogenesis). Recent studies of coal and shale gas systems have characterized in situ microbial communities and provided stable isotope data (δD-CH4, δD-H2O, δ13C-CH4, and δ13C-CO2) from a wider range of environments than available previously. Here we review the principal biogenic methane-yielding pathways in coal beds and shales and the isotope effects imparted on methane, document the uncertainties and inconsistencies in established isotopic fingerprinting techniques, and identify the knowledge gaps in understanding the subsurface processes that govern H and C isotope signatures of biogenic methane. We also compare established isotopic interpretations with recent microbial community characterization techniques, which reveal additional inconsistencies in the interpretation of microbial metabolic pathways in coal beds and shales. Collectively, the re-assessed data show that widely-utilized isotopic fingerprinting techniques neglect important complications in coal beds and shales.Isotopic fingerprinting techniques that combine δ13C-CH4 with δD-CH4 and/or δ13C-CO2have significant limitations: (1) The consistent ~ 160‰ offset between δD-H2O and δD-CH4 could imply that hydrogenotrophic methanogenesis is the dominant metabolic pathway in microbial gas systems. However, hydrogen isotopes can equilibrate between methane precursors and coexisting water, yielding a similar apparent H isotope signal as hydrogenotrophic methanogenesis, regardless of the actual methane formation pathway. (2) Non-methanogenic processes such as sulfate reduction, Fe oxide reduction, inputs of thermogenic methane, anaerobic methane oxidation, and/or formation water interaction can cause the apparent carbon

Simultaneous production of acetate and methane from glycerol by selective enrichment of hydrogenotrophic methanogens in extreme-thermophilic (70 °C) mixed culture fermentation

International Nuclear Information System (INIS)

Zhang, Fang; Zhang, Yan; Chen, Yun; Dai, Kun; Loosdrecht, Mark C.M. van; Zeng, Raymond J.

2015-01-01

Highlights: • Simultaneous production of acetate and methane from glycerol was investigated. • Acetate accounted for more than 90% of metabolites in liquid solutions. • The maximum concentration of acetate was above 13 g/L. • 93% of archaea were hydrogenotrophic methanogens. • Thermoanaerobacter was main bacterium and its percentage was 92%. - Abstract: The feasibility of simultaneous production of acetate and methane from glycerol was investigated by selective enrichment of hydrogenotrophic methanogens in an extreme-thermophilic (70 °C) fermentation. Fed-batch experiments showed acetate was produced at the concentration up to 13.0 g/L. A stable operation of the continuous stirred tank reactor (CSTR) was reached within 100 days. Acetate accounted for more than 90 w/w% of metabolites in the fermentation liquid. The yields of methane and acetate were close to the theoretical yields with 0.74–0.80 mol-methane/mol-glycerol and 0.63–0.70 mol-acetate/mol-glycerol. The obtained microbial community was characterized. Hydrogenotrophic methanogens, mainly Methanothermobacter thermautotrophicus formed 93% of the methanogenogenic community. This confirms that a high temperature (70 °C) could effectively select for hydrogenotrophic methanogenic archaea. Thermoanaerobacter spp. was the main bacterium forming 91.5% of the bacterial population. This work demonstrated the conversion of the byproduct of biodiesel production, glycerol, to acetate as a chemical and biogas for energy generation

Raman studies of methane-ethane hydrate metastability.

Science.gov (United States)

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

2009-03-05

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

Top-down constraints on methane and non-methane hydrocarbon emissions in the US Four Corners

Science.gov (United States)

Petron, G.; Miller, B. R.; Vaughn, B. H.; Kofler, J.; Mielke-Maday, I.; Sherwood, O.; Schwietzke, S.; Conley, S.; Sweeney, C.; Dlugokencky, E. J.; White, A. B.; Tans, P. P.; Schnell, R. C.

2017-12-01

A NASA and NOAA supported field campaign took place in the US Four Corners in April 2015 to further investigate a regional "methane hotspot" detected from space. The Four Corners region is home to the fossil fuel rich San Juan Basin, which extends between SE Colorado and NE New Mexico. The area has been extracting coal, oil and natural gas for decades. Degassing from the Fruitland coal outcrop on the Colorado side has also been reported. Instrumented aircraft, vans and ground based wind profilers were deployed for the campaign with the goal to quantify and attribute methane and non-methane hydrocarbon emissions in the region. A new comprehensive analysis of the campaign data sets will be presented and top-down emission estimates for methane and ozone precursors will be compared with available bottom-up estimates.

Evaluation of the biological methane potential of various feedstock for the production of biogas to supply agricultural tractors

International Nuclear Information System (INIS)

Matuszewska, Anna; Owczuk, Marlena; Zamojska-Jaroszewicz, Anna; Jakubiak-Lasocka, Joanna; Lasocki, Jakub; Orliński, Piotr

2016-01-01

Highlights: • Biochemical methane potential for mixtures of whey, manures and silages was tested. • High impact of feedstock type on composition and yield of biogas was observed. • Simple mathematical model of methanogenic fermentation was proposed. • Exhaust emissions from dual fuel (biogas and diesel oil) engine were investigated. • Using biogas in engine reduces particulate matter and nitrogen oxides emissions. - Abstract: This work is divided into three parts. The first one presents results of biological methane potential of agriculture raw materials available in Poland. In the second part the simple mathematical model of methanogenic fermentation is proposed. The data for this model were obtained from experimental digestion process of chosen mixtures. Last part includes the results of research of exhaust emissions generated by dual dual-fuel engine of agricultural tractor powered by mixture of model biogas (60% and 70% of methane) and diesel oil. The obtained results revealed that there was a significant difference in chemical composition and yield of biogas between considered feedstock types. The highest biogas and methane production was obtained for mixtures in ratio of 6:4 for swine manure/maize silage and whey/grass silage. Due to agriculture conditions in Poland and obtain results, the maize silage and swine manure were chosen to development of mathematical model of fermentation process. It showed a satisfactory match to the experimental results. Results of emission tests on dual-fuel tractor engine supplied with biogas and diesel oil showed the higher concentrations of hydrocarbons and carbon oxide and lower concentrations of particulate matter in exhaust gases. Level of emission of particular components depends on the biogas composition.

Methane Hydrate Field Program: Development of a Scientific Plan for a Methane Hydrate-Focused Marine Drilling, Logging and Coring Program

Energy Technology Data Exchange (ETDEWEB)

Myers, Greg [Consortium for Ocean Leadership, Washington, DC (United States)

2014-02-01

This final report document summarizes the activities undertaken and the output from three primary deliverables generated during this project. This fifteen month effort comprised numerous key steps including the creation of an international methane hydrate science team, determining and reporting the current state of marine methane hydrate research, convening an international workshop to collect the ideas needed to write a comprehensive Marine Methane Hydrate Field Research Plan and the development and publication of that plan. The following documents represent the primary deliverables of this project and are discussed in summary level detail in this final report: Historical Methane Hydrate Project Review Report; Methane Hydrate Workshop Report; Topical Report: Marine Methane Hydrate Field Research Plan; and Final Scientific/Technical Report.

Methane production from cheese whey

Energy Technology Data Exchange (ETDEWEB)

Yan, J Q; Liao, P H; Lo, K V

1988-01-01

Cheese whey was treated in a 17.5-litre laboratory-scale up-flow anaerobic sludge blanket reactor operated over a range of hydraulic retention times and organic loading rates. The reactor performance was determined in terms of methane production, volatile fatty acids conversion and chemical oxygen demand (COD) reduction. At a constant influent strength, the methane production rate decreased with decreasing hydraulic retention time. At constant hydraulic retention time the methane production rate increased as the influent strength was increased up to a concentration of 28.8 g COD litre/sup -1/. The methane production rate was similar for two influent concentrations studied at hydraulic retention times longer than 10 days. The effect of short hydraulic retention times on methane production rate was more pronounced for the higher influent concentration than for the lower influent concentration. The highest methane production rate of 9.57 litres CH/sub 4/ litre/sup -1/ feed day/sup -1/ was obtained at a loading rate of 5.96 g/sup -1/ COD litre/sup -1/ and an influent concentration of 28.8 g COD litre/sup -1/. A high treatment efficiency in terms of chemical oxygen demand reduction was obtained. In general, over 98% removal of chemical oxygen demand was achieved. The results indicated that anaerobic digestion of cheese whey using an upflow sludge blanket reactor could reduce pollution strength and produce energy for a cheese plant.

The California Baseline Methane Survey

Science.gov (United States)

Duren, R. M.; Thorpe, A. K.; Hopkins, F. M.; Rafiq, T.; Bue, B. D.; Prasad, K.; Mccubbin, I.; Miller, C. E.

2017-12-01

The California Baseline Methane Survey is the first systematic, statewide assessment of methane point source emissions. The objectives are to reduce uncertainty in the state's methane budget and to identify emission mitigation priorities for state and local agencies, utilities and facility owners. The project combines remote sensing of large areas with airborne imaging spectroscopy and spatially resolved bottom-up data sets to detect, quantify and attribute emissions from diverse sectors including agriculture, waste management, oil and gas production and the natural gas supply chain. Phase 1 of the project surveyed nearly 180,000 individual facilities and infrastructure components across California in 2016 - achieving completeness rates ranging from 20% to 100% per emission sector at < 5 meters spatial resolution. Additionally, intensive studies of key areas and sectors were performed to assess source persistence and variability at times scales ranging from minutes to months. Phase 2 of the project continues with additional data collection in Spring and Fall 2017. We describe the survey design and measurement, modeling and analysis methods. We present initial findings regarding the spatial, temporal and sectoral distribution of methane point source emissions in California and their estimated contribution to the state's total methane budget. We provide case-studies and lessons learned about key sectors including examples where super-emitters were identified and mitigated. We summarize challenges and recommendations for future methane research, inventories and mitigation guidance within and beyond California.

Structural design of liquid oxygen/liquid methane robotic lander JANUS

Science.gov (United States)

Chaidez, Mariana

As the attempt to send humans to Mars has gained momentum in the last decade, the need to find alternative propellants that are safer, less toxic, and yields a better performance has become apparent [1]. Liquid methane and oxygen have emerged as a suitable alternative. In addition, the incorporation of liquid methane/liquid oxygen into the propulsion system has demonstrated an increase in engine performance, as well as a reduction in the volume, size and complexity of the propulsion system. In an attempt to further understand the technologies that are possible to develop using liquid oxygen (LO 2) and liquid methane (LCH4), a preliminary design of a robotic lander JANUS is being completed by the Center for Space Exploration and Technology Research (cSTER). The structural design of the vehicle is important because it acts as the skeleton of the vehicle and dictates the maneuverability of the robotic lander. To develop the structure of the robotic lander, six different design vehicle concepts with varying tank configurations were considered. Finite Element Analysis (FEA) was completed on each model to optimize each vehicle. Trade studies were completed to choose the best design for JANUS. Upon completion of the trade studies the design for the first prototype of JANUS was initiated in which the tank and thrust modules were designed. This thesis will describe the design process for the structural design of the JANUS.

THE ULTIMATE STATE CONCEPT APPLIED TO TUNNEL SUPPORT

Directory of Open Access Journals (Sweden)

Mladen Hudec

2000-12-01

Full Text Available The most questionable are the values of pressures between rock and support resulting from common deformations on the contact area between rock and support. Therefore the modelling and design of the tunnel support is not reliable, if it is based on active rock pressure resulting from this common deformations. The inversion of the design procedure is proposed. Instead of the active extreme pressure of the rock on support, the influence of ultimate reaction of the support on the rock has to be analysed. This procedure can be performed using the ultimate load principle, as proposed by Eurocodc 7 (Geotechnies. Normally, the rock has the tendency to increase the common conver¬gence until the support reaches its ultimate state. So, loading of profile boundary with the ultimate possible reaction of the support is very plausible. The reactive support pressures have to be probable and itself in equilibrium. The ultimate reactive load has to be reduced by Euro-code safety factor for structural elements and applied on the rock with given properties, or alternatively (as proposed by Eurocode 7 the soil or rock properties have to be diminished and calculated with full ultimate support pressures. If the rock with given (or proposed pro¬perties and loaded with ultimate reactive pressures resulting from supposed support, satisfy its failure criterion, then is the compound system support-rock verificatcd. By this procedure, the number of relevant material properties is reduce to the primary stress ratio and the constants defining the failure criterion. The verification can be performed by any of numerical methods, but we prefer here used boundary elements method (the paper is published in Croatian.

Crenothrix are major methane consumers in stratified lakes.

Science.gov (United States)

Oswald, Kirsten; Graf, Jon S; Littmann, Sten; Tienken, Daniela; Brand, Andreas; Wehrli, Bernhard; Albertsen, Mads; Daims, Holger; Wagner, Michael; Kuypers, Marcel Mm; Schubert, Carsten J; Milucka, Jana

2017-09-01

Methane-oxidizing bacteria represent a major biological sink for methane and are thus Earth's natural protection against this potent greenhouse gas. Here we show that in two stratified freshwater lakes a substantial part of upward-diffusing methane was oxidized by filamentous gamma-proteobacteria related to Crenothrix polyspora. These filamentous bacteria have been known as contaminants of drinking water supplies since 1870, but their role in the environmental methane removal has remained unclear. While oxidizing methane, these organisms were assigned an 'unusual' methane monooxygenase (MMO), which was only distantly related to 'classical' MMO of gamma-proteobacterial methanotrophs. We now correct this assignment and show that Crenothrix encode a typical gamma-proteobacterial PmoA. Stable isotope labeling in combination swith single-cell imaging mass spectrometry revealed methane-dependent growth of the lacustrine Crenothrix with oxygen as well as under oxygen-deficient conditions. Crenothrix genomes encoded pathways for the respiration of oxygen as well as for the reduction of nitrate to N 2 O. The observed abundance and planktonic growth of Crenothrix suggest that these methanotrophs can act as a relevant biological sink for methane in stratified lakes and should be considered in the context of environmental removal of methane.

Impact of Peat Mining and Restoration on Methane Turnover Potential and Methane-Cycling Microorganisms in a Northern Bog.

Science.gov (United States)

Reumer, Max; Harnisz, Monika; Lee, Hyo Jung; Reim, Andreas; Grunert, Oliver; Putkinen, Anuliina; Fritze, Hannu; Bodelier, Paul L E; Ho, Adrian

2018-02-01

Ombrotrophic peatlands are a recognized global carbon reservoir. Without restoration and peat regrowth, harvested peatlands are dramatically altered, impairing their carbon sink function, with consequences for methane turnover. Previous studies determined the impact of commercial mining on the physicochemical properties of peat and the effects on methane turnover. However, the response of the underlying microbial communities catalyzing methane production and oxidation have so far received little attention. We hypothesize that with the return of Sphagnum spp. postharvest, methane turnover potential and the corresponding microbial communities will converge in a natural and restored peatland. To address our hypothesis, we determined the potential methane production and oxidation rates in natural (as a reference), actively mined, abandoned, and restored peatlands over two consecutive years. In all sites, the methanogenic and methanotrophic population sizes were enumerated using quantitative PCR (qPCR) assays targeting the mcrA and pmoA genes, respectively. Shifts in the community composition were determined using Illumina MiSeq sequencing of the mcrA gene and a pmoA -based terminal restriction fragment length polymorphism (t-RFLP) analysis, complemented by cloning and sequence analysis of the mmoX gene. Peat mining adversely affected methane turnover potential, but the rates recovered in the restored site. The recovery in potential activity was reflected in the methanogenic and methanotrophic abundances. However, the microbial community composition was altered, being more pronounced for the methanotrophs. Overall, we observed a lag between the recovery of the methanogenic/methanotrophic activity and the return of the corresponding microbial communities, suggesting that a longer duration (>15 years) is needed to reverse mining-induced effects on the methane-cycling microbial communities. IMPORTANCE Ombrotrophic peatlands are a crucial carbon sink, but this environment

Ultimate disposal of radioactive wastes

International Nuclear Information System (INIS)

Roethemeyer, H.

1991-01-01

The activities developed by the Federal Institution of Physical Engineering PTB and by the Federal Office for Radiation Protection (BfS) concentrated, among others, on work to implement ultimate storage facilities for radioactive wastes. The book illuminates this development from site designation to the preliminary evaluation of the Gorleben salt dome, to the preparation of planning documents proving that the Konrad ore mine is suitable for a repository. The paper shows the legal provisions involved; research and development tasks; collection of radioactive wastes ready for ultimate disposal; safety analysis in the commissioning and post-operational stages, and product control. The historical development of waste management in the Federal Republic of Germany and international cooperation in this area are outlined. (DG) [de

How does free ammonia-based sludge pretreatment improve methane production from anaerobic digestion of waste activated sludge.

Science.gov (United States)

Wang, Dongbo; Liu, Bowen; Liu, Xuran; Xu, Qiuxiang; Yang, Qi; Liu, Yiwen; Zeng, Guangming; Li, Xiaoming; Ni, Bing-Jie

2018-09-01

Previous studies reported that free ammonia (FA) pretreatment could improve methane production from anaerobic digestion of waste activated sludge (WAS) effectively. However, details of how FA pretreatment improves methane production are poorly understood. This study therefore aims to reveal the underlying mechanisms of FA pretreatment affecting anaerobic digestion of WAS through a series of batch tests using either real sludge or synthetic media as the digestion substrates at different pH values. At pH 8.5 level, with an increase of FA level from 18.5 to 92.5 mg/L (i.e., NH+ 4-N: 100-500 mg/L; pH 8.5) the maximum methane yield varied between 194.0 ± 3.9 and 196.9 ± 7.7 mL/g of VSS (25 °C, 1 atm). At pH 9.5 or 10 level, however, with an increase of initial FA level from 103.2 to 516.2 mg/L, the maximal methane yield increased linearly. The mechanism studies revealed that FA pretreatment at high levels not only accelerated the disintegration of WAS but also enhanced the biodegradability of WAS. Although pH in the digesters was adjusted to 7.0 ± 0.1, the high levels of NH+ 4-N added or released led to substantial levels of residual FA ranging from 4.4 to 11.6 mg/L. It was found that this level of FA inhibited homoacetogenesis and methanogenesis significantly, though hydrolysis, acidogenesis, and acetogenesis processes were unaffected largely. Further analyses showed that the inhibition constant of FA to substrate degradation was in the sequence of dextran > glucose > hydrogen > acetate, indicating the methanogenesis process was more sensitive to FA. Copyright © 2018 Elsevier Ltd. All rights reserved.

Differentiation of pre-existing trapped methane from thermogenic methane in an igneous-intruded coal by hydrous pyrolysis

Science.gov (United States)

Dias, Robert F.; Lewan, Michael D.; Birdwell, Justin E.; Kotarba, Maciej J.

2014-01-01

So as to better understand how the gas generation potential of coal changes with increasing rank, same-seam samples of bituminous coal from the Illinois Basin that were naturally matured to varying degrees by the intrusion of an igneous dike were subjected to hydrous pyrolysis (HP) conditions of 360 °C for 72 h. The accumulated methane in the reactor headspace was analyzed for δ13C and δ2H, and mol percent composition. Maximum methane production (9.7 mg/g TOC) occurred in the most immature samples (0.5 %Ro), waning to minimal methane values at 2.44 %Ro (0.67 mg/g TOC), and rebounding to 3.6 mg/g TOC methane in the most mature sample (6.76 %Ro). Methane from coal with the highest initial thermal maturity (6.76 %Ro) shows no isotopic dependence on the reactor water and has a microbial δ13C value of −61‰. However, methane from coal of minimal initial thermal maturity (0.5 %Ro) shows hydrogen isotopic dependence on the reaction water and has a δ13C value of −37‰. The gas released from coals under hydrous pyrolysis conditions represents a quantifiable mixture of ancient (270 Ma) methane (likely microbial) that was generated in situ and trapped within the rock during the rapid heating by the dike, and modern (laboratory) thermogenic methane that was generated from the indigenous organic matter due to thermal maturation induced by hydrous pyrolysis conditions. These findings provide an analytical framework for better assessment of natural gas sources and for differentiating generated gas from pre-existing trapped gas in coals of various ranks.

Comparison of facility-level methane emission rates from natural gas production well pads in the Marcellus, Denver-Julesburg, and Uintah Basins

Science.gov (United States)

Omara, M.; Li, X.; Sullivan, M.; Subramanian, R.; Robinson, A. L.; Presto, A. A.

2015-12-01

The boom in shale natural gas (NG) production, brought about by advances in horizontal drilling and hydraulic fracturing, has yielded both economic benefits and concerns about environmental and climate impacts. In particular, leakages of methane from the NG supply chain could substantially increase the carbon footprint of NG, diminishing its potential role as a transition fuel between carbon intensive fossil fuels and renewable energy systems. Recent research has demonstrated significant variability in measured methane emission rates from NG production facilities within a given shale gas basin. This variability often reflect facility-specific differences in NG production capacity, facility age, utilization of emissions capture and control, and/or the level of facility inspection and maintenance. Across NG production basins, these differences in facility-level methane emission rates are likely amplified, especially if significant variability in NG composition and state emissions regulations are present. In this study, we measured methane emission rates from the NG production sector in the Marcellus Shale Basin (Pennsylvania and West Virginia), currently the largest NG production basin in the U.S., and contrast these results with those of the Denver-Julesburg (Colorado) and Uintah (Utah) shale basins. Facility-level methane emission rates were measured at 106 NG production facilities using the dual tracer flux (nitrous oxide and acetylene), Gaussian dispersion simulations, and the OTM 33A techniques. The distribution of facility-level average methane emission rate for each NG basin will be discussed, with emphasis on how variability in NG composition (i.e., ethane-to-methane ratios) and state emissions regulations impact measured methane leak rates. While the focus of this presentation will be on the comparison of methane leak rates among NG basins, the use of three complimentary top-down methane measurement techniques provides a unique opportunity to explore the

Status and potential of bio-methane fuel

International Nuclear Information System (INIS)

2008-01-01

This document first indicates and describes the various bio-methane production processes which can be implemented on a short term (use of organic wastes or effluents), on a medium term (from energetic crops) and on a longer term (gasification). It discusses and assesses the potential production of bio-methane fuel from different sources and processes. It describes the steps of the production of bio-methane fuel from biogas, with notably biogas refinement to produce bio-methane through three processes (de-carbonation, desulfurization, dehydration). Cost productions are assessed. Expected technology advances are evoked. Finally, the authors outline the contribution of bio-methane in the limitation of greenhouse gas emissions in the transport sector

SAES St 909 pilot scale methane cracking tests

International Nuclear Information System (INIS)

Klein, J. E.; Sessions, H. T.

2008-01-01

Pilot scale (0.5 kg) SAES St 909 methane cracking tests were conducted for potential tritium process applications. Up to 1400 hours tests were done at 700 deg.C, 202.7 kPa (1520 torr) with a 0.03 sLPM feed of methane plus impurities, in a 20 vol% hydrogen, balance helium, stream. Carbon dioxide gettered by St 909 can be equated to an equivalent amount of methane gettered, but equating nitrogen to an equivalent amount of methane was nitrogen feed composition dependent. A decreased hydrogen feed increased methane getter rates while a 30 deg.C drop in one furnace zone increased methane emissions by over a factor of 30. The impact of gettered nitrogen can be somewhat minimized if nitrogen feed to the bed has been stopped and sufficient time given to recover the methane cracking rate. (authors)

Methane Hydrate Field Program. Development of a Scientific Plan for a Methane Hydrate-Focused Marine Drilling, Logging and Coring Program

Energy Technology Data Exchange (ETDEWEB)

Collett, Tim [U.S. Geological Survey, Boulder, CO (United States); Bahk, Jang-Jun [Korea Inst. of Geoscience and Mineral Resources, Daejeon (Korea); Frye, Matt [U.S. Bureau of Ocean Energy Management, Sterling, VA (United States); Goldberg, Dave [Lamont-Doherty Earth Observatory, Palisades, NY (United States); Husebo, Jarle [Statoil ASA, Stavenger (Norway); Koh, Carolyn [Colorado School of Mines, Golden, CO (United States); Malone, Mitch [Texas A & M Univ., College Station, TX (United States); Shipp, Craig [Shell International Exploration and Production Inc., Anchorage, AK (United States); Torres, Marta [Oregon State Univ., Corvallis, OR (United States); Myers, Greg [Consortium For Ocean Leadership Inc., Washington, DC (United States); Divins, David [Consortium For Ocean Leadership Inc., Washington, DC (United States); Morell, Margo [Consortium For Ocean Leadership Inc., Washington, DC (United States)

2013-12-31

This topical report represents a pathway toward better understanding of the impact of marine methane hydrates on safety and seafloor stability and future collection of data that can be used by scientists, engineers, managers and planners to study climate change and to assess the feasibility of marine methane hydrate as a potential future energy resource. Our understanding of the occurrence, distribution and characteristics of marine methane hydrates is incomplete; therefore, research must continue to expand if methane hydrates are to be used as a future energy source. Exploring basins with methane hydrates has been occurring for over 30 years, but these efforts have been episodic in nature. To further our understanding, these efforts must be more regular and employ new techniques to capture more data. This plan identifies incomplete areas of methane hydrate research and offers solutions by systematically reviewing known methane hydrate “Science Challenges” and linking them with “Technical Challenges” and potential field program locations.

Influence of organic loading rate on methane production in a CSTR from physicochemical sludge generated in a poultry slaughterhouse.

Science.gov (United States)

López-Escobar, Luis A; Martínez-Hernández, Sergio; Corte-Cano, Grisel; Méndez-Contreras, Juan M

2014-01-01

The influence of the increase of the organic loading rate (OLR) on methane production in a continuous stirred-tank reactor (CSTR) from physicochemical sludge generated in a poultry slaughterhouse was evaluated. Total solid (TS) to obtain OLR of 1, 5, 10 and 15 g VS L(-1) day(-1), with hydraulic retention times of 29, 6, 6 and 4, respectively, were conditioned. The results showed a decrease in pH levels and an increase in the theoretical volatile fatty acids (VFA). While the yield of methane production decreased from 0.48 to 0.10 LCH4/g VSremoved, respectively, the OLR-10 managed on average 38% removal of volatile solids (VS) and a yield biogas production of 0.81 Lbiogas g(-1) VSremoved and 1.35 L day(-1). This suggests that the OLR increases in an anaerobic system from physicochemical sludge only inhibits the methanogenic metabolism, because there is still substrate consumption and biogas production.

75 FR 9886 - Methane Hydrate Advisory Committee

Science.gov (United States)

2010-03-04

... DEPARTMENT OF ENERGY Methane Hydrate Advisory Committee AGENCY: Department of Energy, Office of Fossil Energy. ACTION: Notice of open meeting. SUMMARY: This notice announces a meeting of the Methane... the Committee: The purpose of the Methane Hydrate Advisory Committee is to provide advice on potential...

Methane emission reduction: an application of FUND

NARCIS (Netherlands)

Tol, R.S.J.; Heintz, R.J.; Lammers, P.E.M.

2003-01-01

Methane is, after carbon dioxide, the most important anthropogenic greenhouse gas. Governments plan to abate methane emissions. A crude set of estimates of reduction costs is included in FUND, an integrated assessment model of climate change. In a cost-benefit analysis, methane emission reduction is

Paradox reconsidered: Methane oversaturation in well-oxygenated lake waters

DEFF Research Database (Denmark)

Tang, Kam W.; McGinnis, Daniel F.; Frindte, Katharina

2014-01-01

The widely reported paradox of methane oversaturation in oxygenated water challenges the prevailing paradigm that microbial methanogenesis only occurs under anoxic conditions. Using a combination of field sampling, incubation experiments, and modeling, we show that the recurring mid-water methane...... peak in Lake Stechlin, northeast Germany, was not dependent on methane input from the littoral zone or bottom sediment or on the presence of known micro-anoxic zones. The methane peak repeatedly overlapped with oxygen oversaturation in the seasonal thermocline. Incubation experiments and isotope...... analysis indicated active methane production, which was likely linked to photosynthesis and/or nitrogen fixation within the oxygenated water, whereas lessening of methane oxidation by light allowed accumulation of methane in the oxygen-rich upper layer. Estimated methane efflux from the surface water...

Energetic conversion of European semi-natural grassland silages through the integrated generation of solid fuel and biogas from biomass: energy yields and the fate of organic compounds.

Science.gov (United States)

Hensgen, Frank; Bühle, Lutz; Donnison, Iain; Heinsoo, Katrin; Wachendorf, Michael

2014-02-01

Twelve European habitat types were investigated to determine the influence of the IFBB technique (integrated generation of biogas and solid fuel from biomass) on the fate of organic compounds and energy yields of semi-natural grassland biomass. Concentration of organic compounds in silage and IFBB press cake (PC), mass flows within that system and methane yields of IFBB press fluids (PF) were determined. The gross energy yield of the IFBB technique was calculated in comparison to hay combustion (HC) and whole crop digestion (WCD). The IFBB treatment increased fibre and organic matter (OM) concentrations and lowered non-fibre carbohydrates and crude protein concentrations. The PF was highly digestible irrespective of habitat types, showing mean methane yields between 312.1 and 405.0 LN CH4 kg(-1) VS. Gross energy yields for the IFBB system (9.75-30.19MWh ha(-1)) were in the range of HC, outperformed WCD and were influenced by the habitat type. Copyright © 2013 Elsevier Ltd. All rights reserved.

The determination of methane resources from liquidated coal mines

Science.gov (United States)

Trenczek, Stanisław

2017-11-01

The article refers to methane presented in hard coal seams, which may pose a serious risk to workers, as evidenced by examples of incidents, and may also be a high energy source. That second issue concerns the possibility of obtaining methane from liquidated coal mines. There is discussed the current methodology for determination of methane resources from hard coal deposits. Methods of assessing methane emissions from hard coal deposits are given, including the degree of rock mass fracture, which is affected and not affected by mining. Additional criteria for methane recovery from the methane deposit are discussed by one example (of many types) of methane power generation equipment in the context of the estimation of potential viable resources. Finally, the concept of “methane resource exploitation from coal mine” refers to the potential for exploitation of the resource and the acquisition of methane for business purposes.

30 CFR 75.323 - Actions for excessive methane.

Science.gov (United States)

2010-07-01

... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Actions for excessive methane. 75.323 Section... excessive methane. (a) Location of tests. Tests for methane concentrations under this section shall be made.... (1) When 1.0 percent or more methane is present in a working place or an intake air course, including...

methanization of organic matters. Guide for project developers

International Nuclear Information System (INIS)

2015-02-01

This document aims at informing potential project developers (farmers, local communities, industrials) all along the creation of a methanization unit. It precisely indicates administrative procedures required to complete a project. It first presents some generalities about methanization (matters and their performance, methanization cycle, biogas), describes methanization processes (dry and humid), and valorisation processes (co-generation, hot water production, gas injection into the public network), presents digestate characteristics, and discusses benefits and drawbacks of methanization. The different steps of a project management are then analysed. Additional procedures are indicated, and risks and traps of methanization projects are highlighted. The document comes along with a large number of appendices which can be documents released by professional or public bodies

International Methane Partnership Fighting Climate Change

Energy Technology Data Exchange (ETDEWEB)

NONE

2007-07-01

Due to the growth of international attention on the problem of climate change combined with the attractiveness of methane mitigation technologies, the capture and use of methane in agriculture, coal mines, landfills, and the oil and gas sector has increasingly become popular over the past few years. Highlighting this, several countries hosted the international 'Methane to Market' Partnership Conference and Exposition in October 2007 in Beijing, China.

Evaluation of a plot-scale methane emission model using eddy covariance observations and footprint modelling

Directory of Open Access Journals (Sweden)

A. Budishchev

2014-09-01

Full Text Available Most plot-scale methane emission models – of which many have been developed in the recent past – are validated using data collected with the closed-chamber technique. This method, however, suffers from a low spatial representativeness and a poor temporal resolution. Also, during a chamber-flux measurement the air within a chamber is separated from the ambient atmosphere, which negates the influence of wind on emissions. Additionally, some methane models are validated by upscaling fluxes based on the area-weighted averages of modelled fluxes, and by comparing those to the eddy covariance (EC flux. This technique is rather inaccurate, as the area of upscaling might be different from the EC tower footprint, therefore introducing significant mismatch. In this study, we present an approach to validate plot-scale methane models with EC observations using the footprint-weighted average method. Our results show that the fluxes obtained by the footprint-weighted average method are of the same magnitude as the EC flux. More importantly, the temporal dynamics of the EC flux on a daily timescale are also captured (r2 = 0.7. In contrast, using the area-weighted average method yielded a low (r2 = 0.14 correlation with the EC measurements. This shows that the footprint-weighted average method is preferable when validating methane emission models with EC fluxes for areas with a heterogeneous and irregular vegetation pattern.

Prospects for methane production and nutrient recycling from lipid extracted residues and whole Nannochloropsis salina using anaerobic digestion

International Nuclear Information System (INIS)

Bohutskyi, Pavlo; Chow, Steven; Ketter, Ben; Betenbaugh, Michael J.; Bouwer, Edward J.

2015-01-01

Highlights: • Semi-continuous AD of untreated and enzymatically pretreated lipid extracted algae. • Coupled biodiesel and methane process yields 40% more energy than biodiesel alone. • Thermal pretreatment (150–170 °C) of whole algae was more effective than enzymatic. • Addition of 5% of AD effluent was optimal to support high growth of Nannochloropsis. • AD effluent can partly replace chemical fertilizer for algal growth. - Abstract: Sustainable mass production of algal biofuels requires a reduction in nutrient demand and efficient conversion into fuels of all biomass including lipid-extracted algal residues (LEA). This study evaluated methane production, nutrient recovery and recycling from untreated and enzymatically pretreated Nannochloropsis LEA using semi-continuous anaerobic digestion (AD). Additionally, this process was compared to methane generation from whole Nannochloropsis alga (WA) and thermally pretreated WA. The methane production from untreated LEA and WA reached up to 0.22 L and 0.24 L per gram of biomass volatile solids (VS), respectively, corresponding to only 36–38% of the theoretical potential. Additionally, observed VS reduction was only 40–50% confirming biomass recalcitrance to biodegradation. While enzymatic treatment hydrolyzed up to 65% of the LEA polysaccharides, the methane production increased by only 15%. Alternatively, WA thermal pretreatment at 150–170 °C enhanced methane production up to 40%. Overall, an integrated process of lipid conversion into biodiesel coupled with LEA conversion into methane generates nearly 40% more energy compared to methane production from WA, and about 100% more energy than from biodiesel alone. Additionally, the AD effluent contained up to 60–70% of the LEA phosphorus content, 30–50% of the nitrogen, sulfur, calcium and boron, 20% of the iron and cobalt, and 10% of manganese, zinc and copper, which can partially replace chemical fertilizers during algal cultivation. Consequently

Yield gap analysis with local to global relevance—A review

NARCIS (Netherlands)

Ittersum, van M.K.; Cassman, K.G.; Grassini, P.; Wolf, J.; Tittonell, P.A.; Hochman, Z.

2013-01-01

Yields of crops must increase substantially over the coming decades to keep pace with global food demand driven by population and income growth. Ultimately global food production capacity will be limited by the amount of land and water resources available and suitable for crop production, and by

Investigations of Methane Production in Hypersaline Environments

Science.gov (United States)

Bebout, Brad M.

2015-01-01

The recent reports of methane in the atmosphere of Mars, as well as the findings of hypersaline paleo-environments on that planet, have underscored the need to evaluate the importance of biological (as opposed to geological) trace gas production and consumption. Methane in the atmosphere of Mars may be an indication of life but might also be a consequence of geologic activity and/or the thermal alteration of ancient organic matter. Hypersaline environments have now been reported to be extremely likely in several locations in our solar system, including: Mars, Europa, and Enceladus. Modern hypersaline microbial mat communities, (thought to be analogous to those present on the early Earth at a period of time when Mars was experiencing very similar environmental conditions), have been shown to produce methane. However, very little is known about the physical and/or biological controls imposed upon the rates at which methane, and other important trace gases, are produced and consumed in these environments. We describe here the results of our investigations of methane production in hypersaline environments, including field sites in Chile, Baja California Mexico, California, USA and the United Arab Emirates. We have measured high concentrations of methane in bubbles of gas produced both in the sediments underlying microbial mats, as well as in areas not colonized by microbial mats in the Guerrero Negro hypersaline ecosystem, Baja California Mexico, in Chile, and in salt ponds on the San Francisco Bay. The carbon isotopic (d13C) composition of the methane in the bubbles exhibited an extremely wide range of values, (ca. -75 per mille ca. -25 per mille). The hydrogen isotopic composition of the methane (d2H) ranged from -60 to -30per mille and -450 to -350per mille. These isotopic values are outside of the range of values normally considered to be biogenic, however incubations of the sediments in contact with these gas bubbles reveals that the methane is indeed being

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

Methane as a climate gas

Energy Technology Data Exchange (ETDEWEB)

Karlsdottir, S.

1996-03-01

This paper was read at the workshop ``The Norwegian Climate and Ozone Research Programme`` held on 11-12 March 1996. Methane is a key component in the atmosphere where its concentration has increased rapidly since pre-industrial time. About 2/3 of it is caused by human activities. Changes in methane will affect the concentrations of other gases, and a model is a very important tool to study sensitivity due to changes in concentration of gases. The author used a three-dimensional global chemistry transport model to study the effect of changes in methane concentration on other trace gases. The model includes natural and anthropogenic emissions of NOx, CO, CH{sub 4} and non-methane hydrocarbons. Wet and dry deposition are also included. The chemical scheme in the model includes 49 compounds, 101 reactions, and 16 photolytic reactions. The trace gas concentrations are calculated every 30 min, using a quasi steady state approximation. Model calculations of three cases are reported and compared. Enhanced methane concentration will have strongest effect in remote regions. In polluted areas local chemistry will have remarked effect. The feedback was always positive. Average atmospheric lifetime calculated in the model was 7.6 years, which agrees with recent estimates based on observations. 8 refs.

Methane emissions from different coastal wetlands in New England, US

Science.gov (United States)

Wang, F.; Tang, J.; Kroeger, K. D.; Gonneea, M. E.

2017-12-01

According to the IPCC, methane have 25 times warming effect than CO2, and natural wetlands contribute 20-39 % to the global emission of methane. Although most of these methane was from inland wetlands, there was still large uncertain in the methane emissions in coastal wetlands. In the past three years, we have investigated methane emissions in coastal wetlands in MA, USA. Contrary to previous assumptions, we have observed relative larger methane flux in some salt marshes than freshwater wetlands. We further detect the methane source, and found that plant activities played an important role in methane flux, for example, the growth of S. aterniflora, the dominate plants in salt marsh, could enhance methane emission, while in an fresh water wetland that was dominated by cattail, plant activity oxided methane and reduced total flux. Phragmite, an invasive plant at brackish marsh, have the highest methane flux among all coastal wetland investigated. This study indicated that coastal wetland could still emit relatively high amount of methane even under high water salinity condiations, and plant activity played an important role in methane flux, and this role was highly species-specific.

Co-Digestion of Sugar Beet Silage Increases Biogas Yield from Fibrous Substrates

Science.gov (United States)

Einfalt, Daniel; Kazda, Marian

2016-01-01

This study tested the hypothesis that the easily degradable carbohydrates of the sugar beet silage (S) will improve the anaerobic digestion of grass silage (G) more profoundly compared to co-digestion of sugar beet silage with maize silage (M). M : S and G : S mixtures were tested in two continuous laboratory-scale AD experiments at volatile solid ratios of 1 : 0, 6 : 1, 3 : 1, and 1 : 3 at organic loading rates of 1.5 kgVS m−3 day−1. While the sugar beet effects in mixtures with maize silage were negligible, co-digestion with grass silage showed a beneficial performance. There, the specific methane production rate was 0.27 lN kg−1VS h−1at G : S ratio of 6 : 1 compared to G : S 1 : 0 with 0.14 lN kg−1VS h−1. In comparison to G : S 1 : 0, about 44% and 62% higher biogas yields were obtained at G : S 6 : 1 and 3 : 1, respectively. Also, the highest methane concentration was found in G : S at ratio of 1 : 3. Synergistic increase of methane yield was found in co-digestion in both experiments, but higher effect was realized in G : S, independently of the amount of sugar beet silage. The findings of this study emphasize the improvement of AD of grass silage by even low addition of sugar beet silage. PMID:27807538

Australian methane fluxes

International Nuclear Information System (INIS)

Williams, D.J.

1990-01-01

Estimates are provided for the amount of methane emitted annually into the atmosphere in Australia for a variety of sources. The sources considered are coal mining, landfill, motor vehicles, natural gas suply system, rice paddies, bushfires, termites, wetland and animals. This assessment indicates that the major sources of methane are natural or agricultural in nature and therefore offer little scope for reduction. Nevertheless the remainder are not trival and reduction of these fluxes could play a significant part in any Australian action on the greenhouse problem. 19 refs., 7 tabs., 1 fig

Retooling the ethanol industry: thermophilic anaerobic digestion of thin stillage for methane production and pollution prevention.

Science.gov (United States)

Schaefer, Scott H; Sung, Shihwu

2008-02-01

Anaerobic digestion of corn ethanol thin stillage was tested at thermophilic temperature (55 degrees C) with two completely stirred tank reactors. The thin stillage wastestream was organically concentrated with 100 g/L total chemical oxygen demand and 60 g/L volatiles solids and a low pH of approximately 4.0. Steady-state was achieved at 30-, 20-, and 15-day hydraulic retention times (HRTs) and digester failure at a 12-day HRT. Significant reduction of volatile solids was achieved, with a maximum reduction (89.8%) at the 20-day HRT. Methane yield ranged from 0.6 to 0.7 L methane/g volatile solids removed during steady-state operation. Effluent volatile fatty acids below 200 mg/L as acetic acid were achieved at 20- and 30-day HRTs. Ultrasonic pretreatment was used for one digester, although no significant improvement was observed. Ethanol plant natural gas consumption could be reduced 43 to 59% with the methane produced, while saving an estimated $7 to $17 million ($10 million likely) for a facility producing 360 million L ethanol/y.

Abiotic production of methane in terrestrial planets.

Science.gov (United States)

Guzmán-Marmolejo, Andrés; Segura, Antígona; Escobar-Briones, Elva

2013-06-01

On Earth, methane is produced mainly by life, and it has been proposed that, under certain conditions, methane detected in an exoplanetary spectrum may be considered a biosignature. Here, we estimate how much methane may be produced in hydrothermal vent systems by serpentinization, its main geological source, using the kinetic properties of the main reactions involved in methane production by serpentinization. Hydrogen production by serpentinization was calculated as a function of the available FeO in the crust, given the current spreading rates. Carbon dioxide is the limiting reactant for methane formation because it is highly depleted in aqueous form in hydrothermal vent systems. We estimated maximum CH4 surface fluxes of 6.8×10(8) and 1.3×10(9) molecules cm(-2) s(-1) for rocky planets with 1 and 5 M⊕, respectively. Using a 1-D photochemical model, we simulated atmospheres with volume mixing ratios of 0.03 and 0.1 CO2 to calculate atmospheric methane concentrations for the maximum production of this compound by serpentinization. The resulting abundances were 2.5 and 2.1 ppmv for 1 M⊕ planets and 4.1 and 3.7 ppmv for 5 M⊕ planets. Therefore, low atmospheric concentrations of methane may be produced by serpentinization. For habitable planets around Sun-like stars with N2-CO2 atmospheres, methane concentrations larger than 10 ppmv may indicate the presence of life.

Methane of the coal

International Nuclear Information System (INIS)

Vasquez, H.

1997-01-01

In the transformation process of the vegetable material to the coal (Carbonization), the products that are generated include CH 4, CO2, N2 and H2. The methane is generated by two mechanisms: below 50 centigrade degree, as product of microbial decomposition, the methanogenic is generated; and above 50 centigrade degree, due to the effects of the buried and increase of the range of the coal, the thermogenic methane is detachment, as a result of the catagenic. The generated methane is stored in the internal surfaces of the coal, macro and micro pores and in the natural fractures. The presence of accumulations of gas of the coal has been known in the entire world by many years, but only as something undesirable for its danger in the mining exploitation of the coal