Amount Of Methane Research Articles

Methane Oxidation in Three Alberta Soils: Influence of Soil Parameters and Methane Flux Rates

Current concern over the potentially negative impacts of climate change has brought attention to anthropogenic sources of methane, a primary greenhouse gas. Two such emission sources are methane leakage at heavy oil wells and sanitary landfills. At both of these sources, substantial quantities of methane could potentially be oxidised by methanotrophic microbes living in soils. Optimisation of this phenomenon may serve as an inexpensive technique for reducing methane emissions. Soil column and batch incubation experiments were performed on a landfill loam, an agricultural loam and a sedge peat to gain a better quantitative understanding of the biological and physical processes limiting CH4 oxidation in soils that undergo the freeze-thaw cycles associated with northern climates. Moisture content emerged as a critical variable that can limit a soil's CH4 oxidation potential. For example, the oxidation rate of the agricultural soil was seen to increase by an order of magnitude after increasing its moisture content from 6% to 10% of its dry weight.

Tribological behavior of a multialkylated cyclopentane oil under ultrahigh vacuum conditions

An ultrahigh vacuum, ball-on-flat test apparatus has been built to study the performance of candidate oils intended for spacecraft applications. Tests have been conducted on a multialkylated cyclopentane base oil using steel balls and disks. Different results are obtained when this oil is tested under vacuum conditions than when it is tested under a nitrogen environment. These differences are dramatic when the tests are conducted under starved conditions. Analyses of gases evolved during rubbing reveal that large quantities of methane are evolving from the process. A mechanism is proposed whereby oxide-free steel surfaces combine with tribological activity to crack the hydrocarbon oil to produce CHx radicals. These CHx radicals abstract hydrogen from the surrounding oil to produce methane. The increased volatility of the oil fragments remaining after methane formation leads to material loss by evaporation, thereby explaining the differences in vacuum and nitrogen performance of the oil.

00/03049 Structural changes of lower rank coals by cation exchange

The lower coalbed methane (CBM) adsorption capacity of the low rank coals is not only related to its lower maturity, but also determined by the coal maceral compositions. In this study, a total of 13 samples including 10 coals and 3 carbonaceous mudstones, were collected from the Middle Jurassic Dameigou Formation in the borehole YQ-1 of the Yuqia Coalfield, northern Qaidam Basin, NW China. Coal lithotypes, maceral compositions, coal ranks, coal facies and methane adsorption characteristics of these samples were investigated using microscopic observation, proximate analysis, porosity analysis, and isothermal adsorption experiments. The results show that the maceral composition has a great influence on the methane adsorption capacity, and the influence of vitrinite on the methane adsorption is generally stronger than that of inertinite at a similar coal rank. For most samples, there is a positive correlation between the vitrinite contents and the Langmuir volume (VL), a negative correlation between the inertinite contents and the VL, and no obvious correlation between the exinite contents and the VL. Furthermore, the vitrinite/inertinite (V/I) ratio also shows a positive relationship with the VL. However, some samples containing large amounts of unfilled fusinite and/or semifusinite have more pore spaces favoring methane adsorption and can also adsorb significant quantities of methane. Consequently, coals with higher vitrinite contents, in association with some unfilled fusinites or semifusinites, should have the greatest adsorption capacity. Coal maceral compositions vary with the types of coal facies, and thus the methane adsorption capacity of coals may be closely related to coal facies. It is found that the methane adsorption capacities of the coals in a wet forest swamp (Type I) and an intergradation forest swamp (Type II) are greater than those in a drained forest swamp (Type III) and an open water peat swamp (Type IV). It is suggested that the area developed with the wet forest swamp and in the intergradation forest swamp with high porosity should be the best target areas for the CBM exploration in the Yuqia Coalfield.

Microbial degradation of phthalic acid esters under anaerobic digestion of sludge

The microbial degradation by anaerobic sludge of three phthalates, priority pollutants, listed by both China National Environmental Monitoring Center and the U.S.EPA, namely, dimethyl (DMP), di- n-butyl (DBP) and di- n-octyl (DOP) phthalates was investigated. The experimental results indicated that the biodegradation rate and the biodegradability of three phthalates under anaerobic conditions appeared to be related to the length of the alkyl-side chains. More than 90% of DMP and DBP with the short alkyl-side chain phthalates can be degraded, whereas the DOP degradation appeared to be relatively slow under the same experimental conditions. The quantity of methane produced was measured and the results showed that both the ester groups and the phthalate ring were mineralized at a significant rate. The kinetics study demonstrated that the biodegradation of three phthalates conformed to the first-order model with respect to their concentrations.

Hidrato de gás submarino: natureza, ocorrência e perspectivas para exploração na margem continental brasileira

Gas hydrates or clathrates are crystalline compounds of water and gas. Natural clathrates trapping mostly methane, are widespreads in the sediments of the continental margins between water depths of 500 3500 m. Clathrates, are rarely sampled in cores but can be detected indirectly by geochemical tracers and by the response of downhole well logs. The extent of hydrates can be mapped using characteristic reflectors and amplitude anomalies on seismic lines. Estimated on this basis, the quantity of methane in marine clathrates is enormous; equivalent in energy value to about twice conventional hydrocarbon resources worldwide. However, exploitation of marine hydrates as a fuel is not as yet technically or economically viable. Major submarine landslides may be triggered by hydrate dissociation due to sea level fall or sea bottom temperature increase. The released gas may enter the atmosphere, and contribute to greenhouse warming. The Brazilian continental margin shows geophysical indicators of gas hydrates in several localities, and geochemical conditions are favourable in others. This gives the possibility of unconventional hydrocarbon plays, but may also pose a geotechnical risk to drilling and production activity.

Estimation of methane emission from a deep-water rice field using Landsat TM and NOAA AVHRR: a case study of Bangkok Plain

A rapid increase in the concentration of greenhouse gases (GHGs) aggravates global warming of the Earth's atmosphere. It is necessary to monitor the emission rate as well as emission quantity of methane as a major component of GHGs. The objective of this study is to develop mathematical models for the estimation of methane emission from a deep-water rice field, using information extracted from satellite images. The methodology proposal in the study consists of two models: firstly, the true ground data of the monthly biomass of rice and average methane emission rate were analysed to set up the methane emission rate model; secondly, the biomass of rice and various reflectances of the wavelength obtained from satellite images were investigated. It has been found that Landsat TM band 3, band 4, band 5, band 7 and the normal differential vegetation index as well as the National Oceanic and Atmospheric Administration AVHRR band 1, band 2 and NDVI are well related to the biomass of rice, which can be used to estimate the biomass of rice, the so-called remote sensing (RS) biomass model Finally the estimation of methane emission can be manipulated by using the methane emission rate model coupled with the RS biomass model based on data from satellite imageries. Comparison between estimated methane emission from satellite images and experimental methane emission data measured at the Prachinburi Rice Research Center reveals that the methodology proposed can be used to estimate methane emission from a deep-water rice field with satisfactory accuracy, particularly during the reproductive stage of rice and maturation.

424 天然ガスエンリッチ浸炭プロセスによる機械的特性向上化

In this study, natural gas was used as raw material and enriched gas of carrier gas, and the development of the system which shortened the carburization time was examined. The mechanical property of the sample which is treated by using this method was evaluated. The control of carbon potential by the oxygen concentration is possible, if enriched gas flow rate in which soot does not arise is chosen, even if the natural gas is used for enriched gas. And, the responsibility is better than carbon potential control by the carbon dioxide concentration. Using the difference between carbon potential calculated from carbon dioxide concentration and and it calculated from oxygen concentration, the system which foresaw the soot generation was developed. By controlling the carbon potential using this system and oxygen sensor, the carburization time was shortened, and retained methane quantity and using enriched gas quantity are drastically decreased.

The use of static mass spectrometry to determine the combined stable isotopic composition of small samples of atmospheric methane

Global budgets of atmospheric trace gases are increasingly being constrained by means of stable isotope measurements. Published analytical techniques for studying the parallel stable isotopic composition of methane (δ13C and δD) require prohibitively large quantities of methane for analysis, making them unsuitable for studies where sample size is small, e.g. soil methane fluxes. A highly sensitive static mass spectrometer has been developed which uniquely uses CH4 as the analyte. The method requires only 8 ng of CH4 for analysis (<10 mL ambient air), making replicated measurements of the isotopic composition of CH4 in small samples feasible for the first time. This paper provides the first detailed description of the instrumentation and the analytical technique. The technique has been used to analyse small samples of air collected in Snowdonia over 21 months. The combined stable isotopic composition (δ17M) ranged from 29.5 to 35.5‰, with an average value of 32.2‰, and was strongly correlated with wind direction (p <0.01, r2 = 0.71). Copyright © 1999 John Wiley & Sons, Ltd.

The use of static mass spectrometry to determine the combined stable isotopic composition of small samples of atmospheric methane.

Global budgets of atmospheric trace gases are increasingly being constrained by means of stable isotope measurements. Published analytical techniques for studying the parallel stable isotopic composition of methane (delta(13)C and deltaD) require prohibitively large quantities of methane for analysis, making them unsuitable for studies where sample size is small, e.g. soil methane fluxes. A highly sensitive static mass spectrometer has been developed which uniquely uses CH(4) as the analyte. The method requires only 8 ng of CH(4) for analysis (<10 mL ambient air), making replicated measurements of the isotopic composition of CH(4) in small samples feasible for the first time. This paper provides the first detailed description of the instrumentation and the analytical technique. The technique has been used to analyse small samples of air collected in Snowdonia over 21 months. The combined stable isotopic composition (delta(17)M) ranged from 29.5 to 35.5 per thousand, with an average value of 32.2 per thousand, and was strongly correlated with wind direction (p <0.01, r(2) = 0.71). Copyright 1999 John Wiley & Sons, Ltd.

Impact of pasture type on methane production by lactating beef cows

In order to determine the quantity of methane (CH4) produced by lactating beef cows on pasture, 16 Hereford–Simmental first-calf heifers with a mean weight of 511.2 ± 5.8 kg were randomly selected from a larger group of cows (n = 60) on a grazing management experiment and used to evaluate the effects of pasture type on ruminal CH4 production using the sulfur hexafluoride (SF6) tracer-gas technique. Pasture treatments consisted of two pasture types, alfalfa-grass [78% alfalfa (Medicago sativa L.) – 22% meadow bromegrass (Bromus biebersteinii Roem and Schult.)] or 100% meadow bromegrass at each of two fertility levels (either unfertilized or soil test recommended fertilizer levels) with two replications of each pasture treatment (8 pastures). Cows were managed using a "put and take" stocking system to leave equal residual herbage mass on all treatments following the grazing period in each paddock. During the 69-d grazing season, two cows from each pasture were sampled to determine daily forage intake and CH4 production on four occasions. The chemical composition of diets differed between pasture types and sampling periods. Dry matter intake was greater for cows grazing alfalfa–grass pastures than for cows grazing grass-only pastures (11.4 vs. 9.7 kg DM d−1. P &lt; 0.018). However, methane production was greater for cows grazing alfalfa–grass pastures than for cows grazing grass-only pastures (373.8 vs. 411.0 L CH4 d−1. P &lt; 0.008). Consequently, energy lost through eructation of CH4 was less for cows grazing alfalfa–grass pastures than it was for cows grazing grass-only pastures (7.1 vs. 9.5% of GEI; P &lt; 0.001). Key words: Methane, cattle, environment, digestion efficiency, pasture, forage

Reaction kinetics of gas generation in selected source rocks of the West Siberian Basin: implications for the mass balance of early-thermogenic methane

About one third of the actual global recoverable natural gas reserves is accumulated in the West Siberian Basin in several super-giant and mega-giant as well as numerous smaller gas fields. The elucidation of the nature of this gas, its mechanisms of formation and accumulation are still a matter of discussion. For instance, it is still not yet clear whether the enormous dry-gas accumulations in Cenomanian reservoirs are of microbial, `early-thermogenic' or catagenetic/metagenetic origin, or if they represent a mixture of these possible formation mechanisms. The present contribution provides new results on the thermal gas generation properties of selected source rocks of the Cretaceous Pokur Formation in the West Siberian Basin. Eight selected source rock core samples of the Pokur Formation and a recent peat sample of the same area were submitted to open-system programmed-temperature pyrolysis, in order to quantify the formation of individual gas compounds, i.e., methane as well as C 2 and C 3 hydrocarbons. The rock samples were selected according to geological age and maturity, i.e., from the Aptian, Albian, and Cenomanian, with the most immature samples from the latter. Organic carbon contents comprise the whole range from 3 to more than 60%, the elevated values representing typical lignites. A reaction kinetic model system was applied to the `generation curves' of the gases resulting in activation energy distributions and the corresponding pre-exponential `Arrhenius factors'. The kinetic data were combined with the temperature history of two selected wells of the Urengoy area obtained from basin modelling in order to calculate the gas generation on the geological time-scale. It was found that, even for the low temperatures occurring in the Pokur Formation, `early' gas generation could have taken place to a certain, yet small, degree. Under the assumption of a respective catchment area and the accumulation of this gas in the reservoirs, however, methane quantities are in the order of magnitude of the Urengoy gas accumulation. Thus, `early-thermogenic' methane could, at least partially, contribute to the gas accumulated in the reservoirs.

Measurements by optical and mass spectrometry of the density of active species in the flowing afterglow of a N2/(10−4–10−3)CH4 plasma

Abstract The influence of small quantities of methane on the behaviour of the active species N, N 2 (A) and N + 2 (B) has been studied by emission and mass spectrometry. The nitrogen atom concentration [N] is in the (0.1–4)×10 15 particles cm −3 range under the experimental conditions investigated. For a N 2 –0.01%CH 4 mixture, [N] is twice as high as for pure N 2 . The metastable N 2 (A) concentration is approximately 10 11 particles cm −3 , i.e. it varies from 3 to 6 times lower than in pure N 2 as the pressure decreases from 25 to 12.5 mbar, and the excited ion density [N + 2 (B)] is 5×10 4 –2×10 6 particles cm −3 , i.e. 100–1000 times lower than in pure N 2 .

砂糖もろこしを用いた嫌気性メタン発酵工程での動力学的相分離に関する研究

A comprehensive study was carried out to examine the possibilities of separating phases by rapid recycle of the leachate from the solid state acidification reactor to the methanation reactor at 55°C with dried sorghum feed.As a control reactor of phase separation system, a plug flow reactor in which solids pass through the reactor and are wasted in the same sequence in which they enter, begin to fail at organic loading rates of greater than 4.0 TVS/l-d. The maximum methane production rate inthis single stage plug flow reactor, approached 1.45 v/v-d and 83.1% TVS removal effciency at a solid retention time of 68 days.The production of 20% of the total system methane in the acidification reactor at organic rates of 30g TVS/l-d indicates that separation of phase was unsuccessfully by a rapid leachate removal. Even though the solids retention time was only 4.6 days, the methanogenes were percent in the acidification reactor to produce a singificant quantity of methane. As organic loading rates increased (5g TVS/l-d to 30g TVS/l-d) the methane production rates of acidification reactor were suppressed from 0.82 v/v-d to 0.72 v/v-d, while the methane production rates of methanation reactor were increased from 0.88 v/v-d to 2.87 v/v-d. The TVS removal efficiencies decreased substantially from 82.1% to 28.8%, as the organic loading rates increased.The average volatile fatty acids concentration of acidification reactor varied from 245 to 175mg/l as acetic acid concentration. The half saturation velocity constant of Monod equation, Ks, for methanogenesis is likely much lower than the substrate concentrations achieved in these studies, approximately 200 mg/las acetic acid.

Thermal analysis of `exploding' [ n]rotanes

The thermal decomposition behavior of four different perspirocyclopropanated macrocyclic oligodiacetylenes, also known as `exploding' [ n]rotanes, was characterized by DSC and EGA. The influence of ring size, number of diethynylcyclopropane segments and permethylation of the cyclopropyl groups on the thermal decomposition is shown. The heat of decomposition surpasses that of conventional explosives. For example, the heat of explosion of [6]rotane calculated by adiabatic thermodynamics is 3426±87 kJ/mol. The kinetic constants of the EGA profile of permethylated [6]rotane are reaction order n=1, activation energy Δ E a=135.3±6.1 kJ/mol and preexponential factor log Z=12.82±1.04. Besides quantities of soot, acetylene, methane and ethene were recorded as decomposition products, and tetramethylethene for permethylated [6]rotane, indicating that the first step in the thermal decomposition of `exploding' [ n]rotanes is the cleavage of the cyclopropane bond.

Hollow cathode synthesis of crystalline CN films

Abstract We describe a novel carbon hollow-cathode RF plasma reactor which has been used to prepare deposits of carbon nitride. Results of the characterization of the deposits by Fourier transform infrared (FTIR) microscopy, Raman microscopy, transmission electron microscopy (TEM), energy-dispersive X-ray analysis and X-ray diffraction are presented. The variation of the properties of the deposits as a function of the deposition conditions is discussed. The inclusion of small quantities of methane in the gas mixture was found to enhance the formation of the CN deposit, but for conditions of maximum enhancement C–H and N–H groups were observed in the deposit. Elemental analysis of the deposit showed that the nitrogen content was ∼57 at.%. A crystalline deposit was obtainable at low substrate temperatures, and the crystals were seen to grow preferentially on defects on the substrate surface.

Influence of a methane atmosphere on the temperature dependence of the conductivity of polycrystalline silicon films

The possibility of using polycrystalline silicon films in gas sensors is investigated. An analysis is made of the influence of a small quantity of methane admitted into the surrounding medium on the temperature dependence of the layer resistivity of films doped with acceptor impurities. It is established that the resistivity increases appreciably in the temperature range between 470 and 500°.

On micro-buoyancy spherical diffusion flames and a double luminous zone structure of the hydrogen/methane flame

Almost spherically symmetry diffusion flames of substantial dimension (diameter ∼ several centimeters) were established in earth gravity by ejecting an O2/N2 mixture from a porous sphere into a subatmospheric pressure environment consisting of low-molecular-weight fuels such as methane and hydrogen. In the present investigation, a double-luminous zone structure, consisting of a green luminous zone near the fuel side, a blue or violet luminous zone near the oxidizer side, and a dark spece between the two luminous zones, was observed for subatmospheric diffusion flames of either air or an O2/N2 mixture against a mixture of hydrogen with a small quantity of methane. The two luminous zones eventually merge with increasing methane addition, characterized by the green luminous zone shifting toward the blue luminous zone. Computational simulation using the experimental boundary conditions shows that the blue and green luminous zones respectively correspond to the main consumption layers of H2Ō2 and CH4: that the breakdown of CH4 is primarily due to its attack by H, leading to the formation of CO, additional H2 and eventually H2O and CO2 and that the electronically excited CO2 and C2 are respectively responsible for the blue and green luminescence. This double-luminous zone structure also exhibits a secondary peak in the heat release rate profile: important reactions accounting for the two heat release peaks were identified.

Microbial Production and Modification of Gases in Sedimentary Basins: Constraints from Isotopic Compositions

Unconventional natural gas reservoirs, such as organic-rich shales and coalbeds, are gaining in economic significance worldwide. Many of these fields contain some portion of microbial methane, either enhancing or replacing thermogenic gas. Importantly, these microbes produce isotopic and compositional effects on the various gas components that often obfuscate their origin. An expanding data set for gases produced from Devonian black shales in the Michigan and Illinois basins, USA, has allowed for a detailed examination of the related chemical and isotopic compositional changes in gas-water systems that trace these processes. The Antrim Shale, within the northern margin of the Michigan Basin, has recently been shown to produce economic quantities of methane that is dominantly bacterial in origin, based on integrated chemical and isotopic analyses of formation waters and co-produced gas (Martini et al., 1996). The most compelling evidence for microbial generation is the correlation between deuterium in methane and coproduced water (Fig. 1). Exploration for economic microbial gas deposits has been linked to low thermal maturity of the host rock organic matter, development of an open, permeable fracture network, and hydrologic conditions that permit freshwater recharge. Further expansion in the Michigan and Illinois basins has allowed us to develop this hypothesis in areas with differing geologic histories and hydrologic settings. Expansion along the western and southern margins of the Michigan Basin at shallow depths within the Antrim Shale has yielded results that are very similar to those previously reported for the northern margin. Waters show evidence of meteoric influx (salinities increasing basinward from subcrop) and microbial activity. Gas chemistries suggest the occurrence of bacterial methanogenesis. In contrast, deeper, midbasin Antrim Shale development has proven unsuccessful. Here, waters show no signs of meteoric mixing, having salinities and stable isotope compositions (O and H) typical of basinal brines. The gases produced include significant volumes of ethane and propane. Importantly, the correlation between the deuterium in methane and that in co-produced waters is absent. These results suggest the gas produced is thermogenic. The isotopic effects of microbial activity are also seen in the 6a3C values of ethane. The 513C values for methane and ethane are plotted against the 51So values of co-produced waters in Fig. 2. The 6~80 values represent the influx of dilute waters, with the most negative values being from shallow wells near the subcrop of the shale, and the most positive values being from deeper wells within the basin. The methane values are invariant while those for ethane become increasingly higher as the ~lSo values of

Methane production by steers on pasture

In order to determine the quantity of methane (CH4) produced by steers on pasture, 16 steers with a mean weight of 356 ± 25 kg were randomly selected from a larger group of cattle (n = 48) to evaluate the effects of grazing management and monensin controlled release capsule (CRC) administration on ruminal CH4 production using the sulphur hexafluoride (SF6) tracer-gas technique. Pasture management treatments consisted of two grazing systems (continuous stocking or 10-paddock rotational stocking) at each of two stocking rates (low, 1.1 steer ha−1 or high, 2.2 steers ha−1) with two replications of each pasture treatment. Half of the animals on each pasture treatment were administered a monensin CRC delivering 270 mg d−1, and untreated animals served as controls. During the 140-d grazing season, one steer from each treatment-replicate combination was sampled to determine daily intake and CH4 production on four occasions. The chemical composition of diets differed between grazing management treatments and sampling periods. Voluntary intake and CH4 production, adjusted for differences in body weight, were unaffected by grazing management, sampling period or by monensin CRC administration and averaged 0.69 ± 0.1 L kg BW−1 d−1 across all grazing management treatments. The energy lost through eructation of CH4 averaged 4.5 ± 1.4% of gross energy intake. Key words: Methane, cattle, environment, digestion efficiency, pasture, forage

Alcohol synthesis in a high-temperature slurry reactor

A family of hydrocarbon liquids has been discovered that is stable at temperatures up to about 400°C in the presence of synthesis gas. The performance of a commercial, ‘zinc chromite’, ‘high pressure’ methanol synthesis catalyst was evaluated in a slurry reactor using two of these liquids, decahydronaphthalene and tetrahydronaphthalene, to suspend the catalyst. The evaluation covered a range of temperatures from 275° to 425°C, total pressures from 6.9 to 17.2 MPa, H 2/CO ratios from 0.5 to 2.0 and space velocities from 1500 to 10 000 sl kg(catalyst) −1 h −1. Methanol was the only significant product at the lower end of this temperature range. The methanol synthesis reaction was close to equilibrium at the highest temperature, and there were significant quantities of dimethyl ether, olefins, methane and carbon dioxide in the product. Catalyst performance was sensitive to the composition of the slurry liquid, but was relatively stable in decahydronaphthalene over a long period of time.