Coal is the combustible, black to brownish-black sedimentary rock comprised of carbon and other elements that is used as an energy source. When it forms, it goes through biological and geological processes that take place over a long period of time. The youngest coal is called peat, which is a traditional fuel in different parts of the world. Other stages include lignite, sub-bituminous, bituminous, and the hardest coal, anthracite. Lignite has the lowest carbon and energy content, while anthracite has the highest.
With the dwindling supply of oil, coal is looking increasingly useful as a replacement energy source, which leads people to ask, ‘how much coal is left in the world?‘ Primarily burned as a fossil fuel to produce electricity and/or heat, coal also has a place in industry circles for the refinement of metals.
The majority of experts agree that there is at least a couple hundred years’ worth of coal remaining in the world. Coal is abundant in America, as well as in many countries around the world. Annual coal production is projected to continue around 1 billion tons into the next century.
With a steady rate of use, it is estimated that coal won’t be depleted for about 265 years . At a rate of growth of only 2% per year, the depletion will occur after 93 years. If the growth rate is 3%, depletion will take place in 73 years.
The leading producers of hard and brown coal (expressed in metric tons) in 2010  include:
- • China – 3,162
- • United States – 997
- • India – 571
- • Australia – 420
- • Indonesia – 336
- • Russia – 324
- • South Africa – 255
- • Poland – 134
- • Kazakhstan – 111
- • Colombia – 74
Coal in the United States
Coal deposits in the eastern part of the United States date back about 300 million years ago – long before dinosaurs roamed the earth. When compared to the eastern states, most of the coal in the West is younger – formed less than 140 million years ago during the Cretaceous period (around the same time dinosaurs were alive). Today, coal is found in 38 states within the U.S. with bituminous coal mostly coming from the Appalachian Basin and the Midwest states.