Due to its abundance, coal has been mined in various parts of the world throughout history and continues to be an important economic activity today. Compared to wood fuels, coal yields a higher amount of energy per mass and could be obtained in areas where wood is not readily available. Though historically used as a means of household heating, coal is now mostly used in industry, especially in smelting and alloy production, as well as electricity generation.
Large-scale coal mining developed during the Industrial Revolution, and coal provided the main source of primary energy for industry and transportation in the West from the 18th century to the 1950s. Coal remains an important energy source, due to its low cost and abundance when compared to other fuels, particularly for electricity generation. However, coal is also mined today on a large scale by open pit methods wherever the coal strata strike the surface and is relatively shallow.
Britain developed the main techniques of underground coal mining from the late 18th century onward with further progress being driven by 19th century and early 20th century progress.
However oil and its associated fuels began to be used as alternative from this time onward. By the late 20th century coal was for the most part replaced in domestic as well as industrial and transportation usage by oil, natural gas or electricity produced from oil, gas, nuclear power or renewable energy sources.
Since 1890, coal mining has also been a political and social issue. Coal miners' labour and trade unions became powerful in many countries in the 20th century, and often the miners were leaders of the Left or Socialist movements (as in Britain, Germany, Poland, Japan, Canada and the U.S.) Since 1970, environmental issues have been increasingly important, including the health of miners, destruction of the landscape from strip mines and mountaintop removal, air pollution, and coal combustion's contribution to global warming.
From http://en.wikipedia.org/
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