|Lamarsh, John R. Introduction to Nuclear Engineering: 3rd Edition. N.P. Prentice Hall, 2001.||"This amounts to about 0.6 cents per kilowatt hour in the mid-1950s"||$1.44/J (US)|
|Adams, Sean Patrick. The US Coal Industry in the 19th Century. EH Net Encyclopedia. Jan 24, 2003. March 22, 2005.||"By 1860 anthracite [coal] sold for about $5.50 in New York City."||$5.00/metric ton (US)|
|Average Price of Coal by State. Energy Info. Admin. 13 June, 2002, 22 May, 2005.||[see table below]||$15.22/metric ton (US)|
|Whole-Tree Chips: An Additional Energy Source for Oklahoma [pdf]. Toms, Martin W. et al. 30, May 2005.||"According to a recent Quarterly Coal Report [J.E. Langwig (Department of Forestry, Oklahoma State University), private communication], the Oklahoma coal price paid by end users was $29.25/ton for the first quarter of 1986."||$26.53/metric ton (US)|
|Rindi White, Rising Coal Prices fuel Sutton re-mining project. Anchorage Daily News. 9 May 2005.||"An April index of coal prices from Barlow Jonker, an Australian firm, lists coal of similar quality to that found at Wishbone Hill at $51.15 per metric ton. Two years ago, the same index listed that coal at $24 per metric ton. But shipping prices have nearly doubled in the same time frame, going from $11.15 to $20.50 per metric ton for a shipment from South Africa to the Netherlands."||$24.00–$51.15/metric ton|
|Coal-Producing State and Region||Underground||Surface||Total|
Coal is a fossil fuel, composed of compacted and chemically altered plant remains. After a time, it becomes sedimentary rock, largely made up of carbon and hydrocarbons. It may be extracted by underground mining, strip mining, or open-pit mining, and its primary function is that of an energy source. Coal comes in the forms of lignite, sub-bituminous coal, bituminous coal, and anthracite, with each stage being achieved after an increasingly large amount of time.
In addition to the common method of combustion, coal can be used in several other was. Gasification is an older method, in which coal-gas was used for lighting, heat, and cooking. It was replaced by the safer natural gas, which is currently used. Liquidification, a second process, turns coal into a liquid gasoline or diesel using one of many different methods. While liquidification has the positive effect of controlling oil prices, it also emits carbon dioxide, a contributor to the threat of global warming, and sulfur dioxide, which can react with water to form acid rain. Trace elements, such as arsenic and mercury, and radioactive isotopes including uranium are all present in coal, and can be released into the environment during this process.
The world coal reserves currently hold one exagram, or 1x10^15 kilograms of coal, and it is estimated that at the contemporary rate of usage, they will last for around 300 years. Coal prices are affected by numerous variables, including world markets and currency exchange rates, the cost of mining and transportation, rival oil prices, and fluctuations in coal stocks. Although there have been significant inconsistencies in these areas, the price of coal remains fairly stable. Coal consumption and production are subsidized by many European countries, despite its proven dangers to the environment, as it provides an alternative to petroleum. Because of a recent consolidation of the main powers in the coal industry, there is less competition, and so changes in price will likely be more pronounced in the future.
Caroline Georges -- 2005