consumption with domestic resources, primarily methane, the main component of natural gas (EIA, 2009b). In addition to its domestic abundance, use of natural gas produces less carbon dioxide and significantly fewer criteria air pollutants2 per unit of energy produced than any other fossil fuel. Natural gas has been described as a principal transition fuel to a less carbon-intensive U.S energy portfolio.
Projections suggest that unconventional natural gas may lead to an increase in the growth of the U.S. gas supply through 2030 (EIA, 2010a). CBM has become a significant part of total U.S. natural gas production over the last decade during which annual CBM production in the 48 conterminous United States increased from 1.3 trillion cubic feet (TCF) to 1.8 TCF, or just below 9.3 percent of total annual U.S. dry natural gas production (EIA, 2010b; see Figure 1.2).
Significant recoverable amounts of CBM occur in numerous sedimentary basins of the United States from the Appalachian and Black Warrior basins in the East to the Powder River, San Juan, Raton, Greater Green, Piceance, and Uinta basins of the West. Extensive CBM resources have also been mapped in Alaska (see Figure 1.3). CBM accumulations