Skip to main content
U.S. flag

An official website of the United States government

Microbial and chemical factors influencing methane production in laboratory incubations of low-rank subsurface coals

January 1, 2008

Lignite and subbituminous coals were investigated for their ability to support microbial methane production in laboratory incubations. Results show that naturally-occurring microorganisms associated with the coals produced substantial quantities of methane, although the factors influencing this process were variable among different samples tested. Methanogenic microbes in two coals from the Powder River Basin, Wyoming, USA, produced 140.5-374.6 mL CH4/kg ((4.5-12.0 standard cubic feet (scf)/ton) in response to an amendment of H2/CO2. The addition of high concentrations (5-10 mM) of acetate did not support substantive methane production under the laboratory conditions. However, acetate accumulated in control incubations where methanogenesis was inhibited, indicating that acetate was produced and consumed during the course of methane production. Acetogenesis from H2/CO2 was evident in these incubations and may serve as a competing metabolic mode influencing the cumulative amount of methane produced in coal. Two low-rank (lignite A) coals from Fort Yukon, Alaska, USA, demonstrated a comparable level of methane production (131.1-284.0 mL CH4/kg (4.2-9.1 scf/ton)) in the presence of an inorganic nutrient amendment, indicating that the source of energy and organic carbon was derived from the coal. The concentration of chloroform-extractable organic matter varied by almost three orders of magnitude among all the coals tested, and appeared to be related to methane production potential. These results indicate that substrate availability within the coal matrix and competition between different groups of microorganisms are two factors that may exert a profound influence on methanogenesis in subsurface coal beds.

Publication Year 2008
Title Microbial and chemical factors influencing methane production in laboratory incubations of low-rank subsurface coals
DOI 10.1016/j.coal.2008.05.019
Authors Stephen H. Harris, Richard L. Smith, Charles E. Barker
Publication Type Article
Publication Subtype Journal Article
Series Title International Journal of Coal Geology
Index ID 70000030
Record Source USGS Publications Warehouse
USGS Organization Central Energy Resources Science Center; Toxic Substances Hydrology Program