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Wen X.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Si J.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | He Z.,CAS Lanzhou Cold and Arid Regions Environmental and Engineering Research Institute | Wu J.,Next Fuel Inc. | And 3 more authors.
Water Resources Management | Year: 2015

Evapotranspiration is a major factor that controls hydrological process and its accurate estimation provides valuable information for water resources planning and management, particularly in extremely arid regions. The objective of this research was to evaluate the use of a support vector machine (SVM) to model daily reference evapotranspiration (ET0) using limited climatic data. For the SVM, four combinations of maximum air temperature (Tmax), minimum air temperature (Tmin), wind speed (U2) and daily solar radiation (Rs) in the extremely arid region of Ejina basin, China, were used as inputs with Tmax and Tmin as the base data set. The results of SVM models were evaluated by comparing the output with the ET0 calculated using Penman–Monteith FAO 56 equation (PMF-56). We found that the ET0 estimated using SVM with limited climatic data was in good agreement with those obtained using the conventional PMF-56 equation employing the full complement of meteorological data. In particular, three climatic parameters, Tmax, Tmin, and Rs were enough to predict the daily ET0 satisfactorily. Moreover, the performance of SVM method was also compared with that of artificial neural network (ANN) and three empirical models including Priestley-Taylor, Hargreaves, and Ritchie. The results showed that the performance of SVM method was the best among these models. This offers significant potential for more accurate estimation of the ET0 with scarce data in extreme arid regions. © 2015, Springer Science+Business Media Dordrecht.

A bioelectrochemical system includes a housing defining an internal chamber. A barrier is disposed within the housing and at least partially separates the internal chamber into first and second compartments. The first compartment including at least one of autotrophic or heterotrophic microorganisms disposed therein. A cathode is disposed within the first compartment and is coupled to a power supply, and an anode is disposed within the second compartment and is coupled to the power supply. The carbon dioxide received within the first chamber is transformed into an organic compound.

Next Fuel Inc. | Date: 2011-08-12

A system includes first and second wells. The first well has a first tube that extends from a first well head to a first end disposed within a coal seam. The second well is disposed at a distance from the first well and includes a second tube that extends from a second well head to a second end disposed within the coal seam. A pump is coupled to the first well and is configured to supply the first tube with pressurized fluid that includes nutrients for methanogenesis. At least a portion of the pressurized fluid introduced into the first tube of the first well is received within the second tube of the second well by way of the coal seam.

Fallgren P.H.,Next Fuel Inc. | Fallgren P.H.,University of Colorado at Denver | Zeng C.,University of Colorado at Denver | Zeng C.,Peking University | And 5 more authors.
International Journal of Coal Geology | Year: 2013

This work reported real-time generation of microbial natural gas (methane) from lignite. Lignite (brown coal) samples and formation water were collected from locations in Australia, Indonesia, and China with no history of natural gas production (zero gas baseline). These samples were set up in microcosms and stimulated for new gas production by amending with essential nutrients. Results show that the Indonesian lignite yielded the highest methane production rate along with the highest enumeration of total bacteria and methanogens. The Australian lignite also produced methane that was associated with a decrease in CO2 composition. The Chinese lignite generated methane, but showed a decrease in methanogen counts, presumably due to microbial community shift. Overall, the results from this preliminary study indicate that application of nutrients to lignite can realize real-time methane production. Further molecular biology analysis is required to determine the constitution and shift in microbial populations during the process of methane generation from lignite. © 2013 Elsevier B.V.

Fallgren P.H.,Next Fuel Inc. | Jin S.,Next Fuel Inc. | Jin S.,University of Wyoming | Zeng C.,University of Colorado at Denver | And 4 more authors.
International Journal of Coal Geology | Year: 2013

Biogenic natural gas production is often associated with low-rank coals such as lignite (brown coal) and subbituminous coal; however, little work has been done to determine the potential of stimulating microbial methane production in higher-rank coals. Reference samples of lignite, subbituminous, high-volatile bituminous, and low-volatile bituminous coal samples were obtained. A laboratory feasibility study was conducted in anaerobic microcosms containing each type of coal and amended with a nutrient solution and a methanogenic consortium of organisms enriched from formation water obtained from a coalbed methane well with a known history of biogenic gas production. Headspace analysis of the microcosms indicated that methane production rates were higher in the two bituminous coals than in the lower rank coals. The results suggest the potential for enhancing biogenic natural gas production from bituminous coals with a focus on liberating trapped volatile organic compounds. © 2013 Elsevier B.V.

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