Coal (from the Old English term col, which has meant "mineral of fossilized carbon" since the 13th century) is a combustible black or brownish-black sedimentary rock usually occurring in rock strata in layers or veins called coal beds or coal seams. The harder forms, such as anthracite coal, can be regarded as metamorphic rock because of later exposure to elevated temperature and pressure. Coal is composed primarily of carbon along with variable quantities of other elements, chiefly hydrogen, sulfur, oxygen, and nitrogen.

Throughout history, coal has been a useful resource. It is primarily burned for the production of electricity and/or heat, and is also used for industrial purposes, such as refining metals. A fossil fuel, coal forms when dead plant matter is converted into peat, which in turn is converted into lignite, then sub-bituminous coal, then bituminous coal, and lastly anthracite. This involves biological and geological processes that take place over a long period.

Coal is the largest source of energy for the generation of electricity worldwide, as well as one of the largest worldwide anthropogenic sources of carbon dioxide releases. In 1999 world gross carbon dioxide emissions from coal usage were 8,666 million tonnes of carbon dioxide.

Coal-fired electric power generation emits around 2,000 pounds of carbon dioxide for every megawatt-hour generated, which is almost double the carbon dioxide released by a natural gas-fired electric plant per megawatt-hour generated. Because of this higher carbon efficiency of natural gas generation, as the fuel mix in the United States has changed to reduce coal and increase natural gas generation, carbon dioxide emissions have unexpectedly fallen. Those measured in the first quarter of 2012 were the lowest of any recorded for the first quarter of any year since 1992.

Coal is extracted from the ground by coal mining, either underground by shaft mining, or at ground level by open pit mining extraction.

The top hard and brown coal producers in 2010 (and 2009) were (in millions of tons): China 3,162 (2,971); United States 997 (985); India 571 (571); Australia 420 (399); Indonesia 336 (301); Russia 324 (297); South Africa 255 (247); Poland 134 (135); Kazakhstan 111 (101); and Colombia 74 (73).

Read more about Coal:  Formation, Types, Early Uses As Fuel, Cultural Usage, Coal As A Traded Commodity, Environmental Effects, Economic Aspects, Energy Density and Carbon Impact, Underground Fires, Production Trends

Other articles related to "coal":

Enugu - Economy
... See also Economy of Nigeria Nicknamed the Coal City, Enugu's economy in the early 20th century depended on coal mining in the Udi plateau this industry was the ... The Nigerian Coal Corporation has been based in Enugu since its creation in 1950 where it controlled coal mining ... war brought widespread devastation that forced a decline in coal production from damage or destruction of equipment ...
White Coal
... White coal is a form of fuel produced by drying chopped wood over a fire ... White coal was used in England to smelt lead ore from the mid-sixteenth to the late seventeenth centuries ... White coal could be use mixed with charcoal for other industrial uses than lead smelting ...
Production Trends - Major Coal Importers
... Imports of Coal by Country and year (million short tons) Country 2010 ... Share Japan 199.7 209.0 206.0 182.1 206.7 17.5% China 42.0 ...
Badlands - Features
... Coal seams are also exposed in some badlands, so historically, coal mining districts have developed in badlands areas ... this is the Drumheller district of the Red Deer River in Alberta, where the Atlas Coal Mine historical site preserves the last of 139 mines that operated in the badlands ...
Enugu - Geography - Topography
... Cross River basin and the Benue trough and has the best developed coal in this area ... Precambrian basement rock in this region is overlaid with sediments bearing coal from the Cretaceous and Tertiary age ... Coal seams in the Enugu coal district measure between 1 and 2 metres (3.3 and 6.6 ft) in thickness and the reserves have been estimated to be more than 300 million tonnes ...

Famous quotes containing the word coal:

    Coal is a portable climate. It carries the heat of the tropics to Labrador and the polar circle; and it is the means of transporting itself whithersoever it is wanted. Watt and Stephenson whispered in the ear of mankind their secret, that a half-ounce of coal will draw two tons a mile, and coal carries coal, by rail and by boat, to make Canada as warm as Calcutta, and with its comfort brings its industrial power.
    Ralph Waldo Emerson (1803–1882)

    Writing is to descend like a miner to the depths of the mine with a lamp on your forehead, a light whose dubious brightness falsifies everything, whose wick is in permanent danger of explosion, whose blinking illumination in the coal dust exhausts and corrodes your eyes.
    Blaise Cendrars (1887–1961)

    This island is made mainly of coal and surrounded by fish. Only an organizing genius could produce a shortage of coal and fish at the same time.
    Aneurin Bevan (1897–1960)