There are several measures used to determine how much coal is left in the United States. These measures are based on various degrees of geologic certainty and the economic feasibility of mining the coal.
Did you know?
Six states had 75% of the demonstrated reserve base (DRB) of coal as of January 1, 2014:
Eighteen other states had 25% of the DRB.
Coal reserves at producing mines
Coal mining companies report to the U.S. Energy Information Administration (EIA) the amount of recoverable reserves at U.S. coal mines that produced at least 25,000 short tons of coal (or 10,000 short tons of anthracite coal) in a year.
As of January 1, 2014, there were 197 billion short tons of recoverable reserves at producing mines.
The amount of coal reserves at producing mines is a small portion of the total amount of coal that exists in the United States.
How much coal is there?
It is not possible to know exactly how much coal exists in the United States because it is buried underground, but it is possible to make estimates.
- Total resources is EIA's best estimate of the total amount of coal (including undiscovered coal) in the United States. Total resources are estimated to be about 4 trillion short tons.1 Total resources includes several categories of coal with various degrees of geologic assurance and data reliability.
- The Demonstrated Reserve Base (DRB2) is the sum of coal in both measured and indicated resource categories of reliability. This represents 100% of the in-place coal that could be mined commercially at a given time. EIA estimates that the DRB in 2013 was 479.9 billion short tons.
- Estimated recoverable reserves include only the coal that can be mined with today's mining technology, after considering accessibility constraints and recovery factors. EIA estimates there are 256.7 billion short tons of U.S. recoverable coal reserves, about 53% of the DRB.
Based on U.S. coal production in 2013 at 984.8 million short tons, the U.S. estimated recoverable coal reserves would last about 261 years. The actual number of years that those reserves will last depends on changes in production and reserves estimates.
What are international coal reserves?
As of December 31, 2011, total world proved recoverable reserves of coal were estimated at 979.8 billion short tons.
Five countries have 73% of the world's coal reserves:
1The most comprehensive national assessment of U.S. coal resources was published by the U.S. Geological Survey (USGS) in 1975, which indicated that as of January 1, 1974 coal resources in the United States totaled 4 trillion short tons. Although more recent regional assessments of U.S. coal resources have been conducted by the USGS, a new national level assessment of U.S. coal resources has not been conducted.
2The U.S. Bureau of Mines made an assessment of the portion of demonstrated resources that was suitable for mining with existing technologies. As of January 1, 1971, the U.S. Bureau of Mines estimated that 434 billion short tons of coal in the demonstrated resource categories lied within what they deemed to be minable coal deposits. The U.S. Bureau of Mines' estimate, published in the 1975 USGS report on U.S. coal resources, was referred to as the DRB of coal. However, it was estimated for 1971, so subsequent updates to the DRB reflecting downward adjustments for production begin with data reported for 1971.
3EIA is responsible for the DRB. EIA's most recent estimate indicated that there were 479.9 billion short tons of in-place coal reserves in the DRB as of January 1, 2014. This estimate is 46 billion short tons higher than the original estimate provided by the U.S. Bureau of Mines in 1971. The difference in estimates is primarily a result of new regional assessments of coal resources over the years that have added additional resource tonnage.