U.S. Coal Resource Regions

In the United States, coal resources are larger than remaining natural gas and oil resources. Annually, EIA reports remaining tons of coal in the demonstrated reserve base (DRB), which is composed of coal resources that have been identified to specified levels of accuracy and may support economic mining under current technologies.  As of January 1, 2007, the DRB was estimated to contain 491 billion short tons (a short ton is a unit of weight equal to 2,000 pounds).

Between 1990 and 1999, EIA obtained updated coal reserves information and data largely through its Coal Reserves Data Base (CRDB) program. That program encouraged State agencies to revise coal resource and reserves estimates in their respective States. These revised coal reserve estimates include improved analyses of coal quality, accessibility, and recoverability in the study areas.  EIA used these new data to revise the DRB.

EIA initiated a new coal reserves project in 2008 to incorporate existing reserves data into a geographic information system (GIS) based program. This system will include existing data, plus U.S. Geological Survey data, particularly for the Powder River Basin area of Montana and Wyoming.

Recovery rates vary greatly between underground and surface mining. The proportion of coal resources that can be recovered (i.e. mined) economically from undisturbed deposits varies from less than 40 percent in some underground mines to more than 90 percent at some surface mines. In some underground mines, by design a portion of the coal is left intact as pillars to protect against surface collapse. Adverse geologic features in a mining area, such as folding, faulting, and inter-layered rock strata, can limit the amount of coal recovered at some underground and surface mines.

Access to some coal is limited.  Because of property rights, land use conflicts, and physical and environmental restrictions, EIA estimates that only about 50 percent of the demonstrated reserve base (DRB) may be available or accessible for mining.

EIA annually estimates recoverable coal reserves by adjusting the DRB to reflect accessibility and recovery rates in mining. As of January 1, 2007, EIA estimated that the remaining U.S. recoverable coal reserves totaled over 264 billion short tons, from a demonstrated reserve base of 491 billion short tons.

Recoverable coal reserves at producing mines represent the quantity of coal that can be recovered from existing coal reserves at reporting mines. These reserves essentially reflect the working inventory at producing mines. In 2005, the recoverable reserves at producing mines were 18.9 billion short tons.  EIA conducts an annual survey to gather and report the quantity of recoverable coal reserves at producing mines.

There are four major ranks of coal in the U.S. classification scheme. In the United States, coal rank is classified according to its heating value, its fixed carbon and volatile matter content, and, to some extent, its caking properties during combustion. The coal ranks from highest to lowest in heating value are:

• anthracite
• bituminous
• subbituminous
• lignite.

Of the four ranks, bituminous coal accounts for over half (53 percent) of the DRB. Bituminous coal is concentrated primarily east of the Mississippi River, with the greatest amounts in Illinois, Kentucky, and West Virginia.

All subbituminous coal (37 percent of the DRB) is west of the Mississippi River. Most subbituminous coal is in Montana and Wyoming.

Lignite, the lowest-rank coal, accounts for about 9 percent of the DRB. Lignite is found mostly in Montana, Texas, and North Dakota.

Anthracite, the highest-rank coal, makes up only 1.5 percent of the DRB. Anthracite is concentrated almost entirely in northeastern Pennsylvania.
      
What are international coal resources? Worldwide, compared to all other fossil fuels, coal is the most abundant and widely distributed across the continents. Estimates of the world's total recoverable reserves of coal in 2004 were about 998 billion short tons. The resulting ratio of coal reserves to production is approximately 164 years, meaning that at current rates of production (and no change in reserves), coal reserves could theoretically last for more than one and one-half centuries.

The distribution of coal reserves around the world varies notably from that of oil and gas. Significant reserves are found in the United States and Russia but not in the Middle East. The United States with 27 percent and Russia with 17 percent account for nearly half of global coal reserves. China (13 percent), Australia (9 percent), South Africa (5 percent), and Kazakhstan (3 percent) also have significant amounts of the world's recoverable coal reserves.

More information on this subject can be found in the following EIA publications:
    View all of the tables from the Annual Coal Report
    View an (HTML) summary of the coal industry for the most recent year.
    View all of the tables from the Quarterly Coal Report

See also:
    Projected Coal Supply & Demand to 2030 in Annual Energy Outlook
    Historical Coal Data back to 1949
    International Coal Data
    Additional basic information about coal