--> Abstract: Laboratory Studies of Biogenic Methane Production from Coal by Microbial Consortia: Identifying Organisms, Reactions and Intermediates, by Elizabeth J. Jones, Mary A. Voytek, William H. Orem, Margo D. Corum, Anne L. Bates, and Harry E. Lerch; #90078 (2008)

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Laboratory Studies of Biogenic Methane Production from Coal by Microbial Consortia: Identifying Organisms, Reactions and Intermediates

Elizabeth J. Jones1, Mary A. Voytek1, William H. Orem2, Margo D. Corum2, Anne L. Bates2, and Harry E. Lerch2
1Water Resources, U.S. Geological Survey, Reston, VA
2Geology, U.S. Geological Survey, Reston, VA

Isotopic studies have indicated that some coal beds produce methane of biogenic origin. Little is known, however, about the organisms, reactions and intermediates involved in the process of biogenic methane formation from geopolymers like coal. Laboratory microcosms of coal and nutrients, some with an added microbial consortium (WBC-2) enriched from a modern wetland, were used to study the production of methane from coal. Subbituminous coal samples from the Wilcox Group (Zavala Co. TX) and the Fort Union Formation (Campell Co. WY), both known to produce biogenic methane in the field, released 56 and 16 scf/ton of methane, respectively, in laboratory experiments with WBC-2 added. Generation of methane from coal involves a consortium of microorganisms that ferment complex organics to methanogenic substrates which are then converted to methane. Microbial biomass in the coals was low and methane generation was limited by methanogen growth, which did not always occur. When WBC-2 was added, organics released from the coal [predominantly long chain fatty acids (LCFAs) and alkanes] were degraded over about 70 days. Acetate accumulated initially, then decreased as methane was formed. WBC-2 also produced methane in coal-free treatments with organics such as octadecanoic, hexadecanoic, benzoic and vanillic acids confirming that coal intermediates can be fermented to methane precursors. There was a shift in the WBC-2 microbial population grown in coal microcosms, indicating growth of some new dominant members specific to coal fermentation. Phylogenetic identification of community members in the coal incubations will be useful for understanding and manipulating in situ coalbed populations.

 

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas