U.S. Geological Survey
Energy Resource Surveys Program
"For the past 100 years or so, U.S. Geological Survey scientists have reported the amount of remaining coal by estimating the total endowment and then subtracting the amount already extracted. Now, U.S. Geological Survey scientists extend the process as they complete coal availability studies to produce estimates of available coal when various restrictions are imposed. The process is conceptually simple, but is complicated by very large volumes of disparate data. The results, however, have proved to be valuable to local and regional planners."
M. Devereux (Debbie) Carter, U.S. Geological Survey
Coal accounts for a major portion of our Nation's projected future energy supply.
A demonstrated reserve base estimated at nearly 475 billion short tons suggests that the United States has enough coal to meet projected energy needs for almost 200 years, based on current consumption rates. However, the traditional procedures used for estimating the demonstrated reserve base do not account for many environmental and technological restrictions placed on coal mining. Consequently, such traditional estimates of resource quantity are no longer sufficient to guide policy at Federal, State, and local levels. Planners demand better knowledge of the net amount of coal considering restrictions imposed by technology, geology, and societal, environmental, and economic factors.
The needs of local and regional planners for meaningful estimates of coal resources have increased over the past decade.
U.S. Geological Survey (USGS) and State workers developed a new method to determine the quantity of coal that might actually be available for mining under current and foreseeable conditions. The method is unique in its approach because it applies restrictions to the coal resource before it is mined. Earlier methods incorporated restrictions as part of a recovery factor (a percentage) which was then applied globally to the reserve (minable coal) tonnage to derive a recoverable coal quantity. None of the previous methods defined the restrictions or delineated their area, and the specific impact. Because these restrictions and their impact are determined in this new method, it is now possible to achieve more accurate and specific estimates of available coal resources. When all factors are considered, significantly less coal is actually available for extraction and marketing than previously has been estimated.
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USGS scientists initiated a cooperative program to identify major constraints on availability of coal and to estimate resulting resources.
This cooperative program was initiated with the State Geological Surveys of Kentucky, Virginia, and West Virginia. Twenty 7.5-minute quadrangles were chosen to represent variations in geology, topography, and culture of the Central Appalachian region. Land-use restrictions, defined by Federal, State, or other regulations, are constraints placed on mining by societal policies to protect such features as buildings, streams, and wildlife habitats, and are primarily applicable to surface mining activities. Technological restrictions, such as coalbeds being too thin, too deep, or too close together to mine, or other adverse geological factors, generally have a more significant impact on underground mining activities.
USGS researchers successfully completed a pilot study to test the new assessment method.
A pilot study was conducted in cooperation with Dr. James C. Cobb, Assistant State Geologist, and his colleagues at the Kentucky Geological Survey in the Matewan 7.5-minute quadrangle in eastern Kentucky. Pertinent geologic, mining, land-use, and technological data were collected and the model was applied to the data to eliminate coal affected by land-use or technological restrictions. Neither recovery factors nor economic factors are considered in the model although these would ultimately need to be included. Results indicate that of the original 986.5 million short tons of coal in the quadrangle, 13 percent has been mined and 25 percent is restricted, leaving 62 percent of the original or about 612 million short tons of coal available for mining. However, only 44 percent of this available coal, or about 266 million short tons, complies with environmental constraints. Additionally, more coal is lost during mining and cleaning.
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Original coal resources minus coal mined and lost-in-mining minus restrictions equals available coal resources, as depicted by the Upper Elkhorn No. 2 coal bed in the Matewan 7.5- minute quadrangle, Kentucky and West Virginia.
USGS and State scientists provide data and results to the U.S. Bureau of Mines (USBM) for economic analysis.
Results of coal availability studies are transferred to USBM for further analysis of available coal considering recovery, economic, and environmental factors. Based on 15 coal availability studies and subsequent USBM analyses of five quadrangles in the central Appalachian region, some generalizations about coal availability are possible. Of the original coal resource in the ground (100 percent), only about 5 percent may eventually be marketed because of losses resulting primarily from mining operations, societal and technological restrictions, and economic factors. So, although some areas are well endowed with coal, local and regional planners must carefully evaluate the amount of coal resource that actually is available for development.
USGS coal availability studies are being extended to 11 major coal-bearing regions across the United States.
The program to study coal availability is limited to a representative sampling of the total area of the 11 coal regions. Chosen quadrangles are considered to be representative of the region in terms of geology, culture, mining practices, topography, and other relevant factors, although there is widespread recognition that conditions will vary locally. There are an estimated 5,800 7.5-minute quadrangles in the major coal-bearing areas of the United States of which 150 will be studied over the 15-year life of this activity, which concludes in 2001.
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Results of 15 USGS/State and 5 USBM studies, showing agency areas of responsibility.
Phone: (703) 648-6413
E-mail: mdcarter@usgs.gov