Coal bed methane extraction (CBM extration) is a method for extracting methane from a coal deposit. The methane is dissolved in subsurface water in the coal seam. To economically retrieve reserves of methane, wells are drilled into the deposit, water is pumped out, then the methane is extracted, compressed and piped to market. The goal is to decrease the water pressure by pumping some of the water through the well. The decrease in pressure coaxes dissolved methane into its gaseous form, enabling it to be recovered. Disposal of the water, which may contain impurities such as salt, presents an environmental problem as does the resulting lowering of the water table. Seven percent of the natural gas (methane) currently produced in the United States comes from CBM extraction.

This process involves the drilling of tens of thousands of wells, and extensive support facilities such as roads, pipelines and compressors.

The use of this method is currently expanding with great controversy in the Powder River Basin.

External links

• Power River Showdown, New York Times editorial, August 4, 2002 (regarding proposed project)

• http://waterquality.montana.edu/docs/methane/cbmfaq.shtml#how_much_methane_gas_is_estimated_will_be_extracted_from_the_powder_river_basin