Historical trends in American coal production and a possible future outlook

The United States has a vast supply of coal, with almost 30% of world reserves [BP, 2008. BP Statistical Review of World Energy 2008. accessed 16 February 2009] and more than 1600 Gt (short) as remaining coal resources [Ruppert, L., Kirshbaum, M., Warwick, P., Flores, R., Affolter, R., Hatch, J., 2002. The US Geological Survey's national coal resource assessment: the results. International Journal of Coal Geology, 50, 247–274]. The US is also the world's second largest coal producer after China and annually produces more than twice as much coal as India, the third largest producer [BP, 2008. BP Statistical Review of World Energy 2008. accessed 16 February 2009].The reserves are concentrated in a few states, giving them a major influence on future production. Historically many states have also shown a dramatic reduction in recoverable coal volumes and this has been closely investigated. Current recoverable estimates may also be too high, especially if further restrictions are imposed. The average calorific value of US coals has decreased from 29.2 MJ/kg in 1950 to 23.6 MJ/kg in 2007 as U.S. production moved to subbituminous western coals [Annual Energy Review, 2007. EIA – Annual Energy Review 2007. DOE/EIA-0384(2007), accessed 16 February 2009]. This has also been examined in more detail.This study also uses established analysis methods from oil and gas production forecasting, such as Hubbert linearization and logistic curves, to create some possible future outlooks for U.S. coal production. In one case, the production stabilizes at 1400 Mt annually and remains there until the end of the century, provided that Montana dramatically increases coal output. The second case, which ignores mining restrictions, forecasts a maximum production of 2500 Mt annually by the end of the century.