Potential Carbon Dioxide Sequestration and Enhanced Coalbed Methane Production in the Powder River and Williston Basins

摘要

Increased carbon dioxide (CO_2) emission from coal-fired, electric-generating power plants from developed and developing countries of the world led to the Kyoto Conference in 1997, where the participating countries agreed to reduce emissions of greenhouse gases below the 1990 level by the year 2012. One approach to reduce greenhouse gas emissions, particularly the CO_2 emission from coal-fired power plants, is to store the gas in various sinks. Gas emissions may be stored or sequestered in three ways: biosphere sinks, such as oceans, forests, and agricultural soils; geosphere or geological sinks, such as depleted oil and gas reservoirs, deep rock aquifers, and coal beds; and material sinks, such as chemicals, plastics, fertilizers, and wood products (Gentzis, 2000). This paper discusses new data on the CO_2 adsorption of low-rank coal as well as the older CO_2 adsorption results of Stanton and others (2000). Both studies point to potential sequestration of CO_2 in lower-rank coal such as the subbituminous coal and lignite in the Fort Union Formation (Paleocene) in the Powder River and Williston Basins. These coal beds could be utilized as a geological sink to sequester CO_2 emitted from coal-fired power plants in and near the Powder River Basin in Wyoming and Montana, and in the Williston Basin in North Dakota and South Dakota (fig. 1). CO_2 sequestration is possible in coal beds because a common estimate of CO_2 adsorption by coal is assumed to be about twice that of methane. These basins contain large low-rank coal resources that are currently being mined to supply fuel for 17 power plants in and near the basins. The short distance of transportation of CO_2 from these powerplants to the coal-bed storage sites in the basins make this an ideal method for sequestration.