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During the Carboniferous
Era some 300 million years ago lush tropical plants grew and then
geological changes crushed and compressed the plants. With time they
were converted to carbon in its many forms which are mainly coal,
oil and natural gas. Continental drift then distributed
these
storehouses of energy around the globe, near to where our various
modern civilizations then developed. 306
million years ago (U.S. Geological Survey)
Reserves
of coal are estimated to be 8 x 1012
tonnes with annual consumption of 5x 109 tonnes.
<US Global
Change Research Program>. It is unlikely that we will run out
of easily
accessible coal deposits in this century. Because coal
is such a low cost source of energy it is likely to remain an
attractive energy source for producing electricity and for refining
metals.
<Intergovernmental Panel
on Climate Change>.
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Introduction
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