Assessment of Coal Geology, Resources, and Reserve Base in the Powder River Basin, Wyoming and Montana [open pdf - 7MB]
"The U.S. Geological Survey (USGS) is responsible for providing objective scientific information to support decisions regarding land management, environmental quality, and economic, energy, and strategic policy. To accomplish this goal, the USGS periodically assesses the Nation's endowment of various energy resources, including coal. Because the amount of economically recoverable coal resource is substantially less than the total original volume of coal in place, coal reserve base estimates provide essential information for energy-related decisions […]. To be classified as 'reserves,' the coal must be considered economically producible at the time of classification. Regional-scale reserve estimates are based on prefeasibility scoping-level studies in turn based on conceptual mine designs. Prefeasibility studies have a higher degree of uncertainty than feasibility studies developed for commercialization of a specific property. Conceptual mine designs do not have sufficient detail to support a final decision by a financial institution to support development of a coal deposit to the production stage. The goal of the current USGS United States Coal Resources and Reserves Assessment Project is to conduct regional-scale, coal resource and reserve assessments of the significant coal beds in all major U.S. coal basins. The Powder River Basin (PRB) in northeastern Wyoming and southeastern Montana […] was the first basin to be assessed under this effort. It contains the largest deposits of low-sulfur subbituminous coal in the world."
Fact Sheet 2012-3143
U.S. Geological Survey: http://www.usgs.gov/