Environmental Engineering Reference
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extracted less than 20 Mt in 2000, and its peak labor
force of 1.25 million miners in 1920 was reduced to
fewer than 10,000 (Hicks and Allen 1999). Many Af-
rican and Asian countries use no coal, but in 2005 the
fuel still provided 76% of South Africa's, nearly 70% of
China's, and nearly three-fifths of India's TPES, but
only 24% of the U.S. and 16% of the Russian (BP 2006).
Another perspective on coal's absolute rise and relative
decline is offered by the fact that during the twentieth
century the energy content of extracted coals increased
less than 4.5 times although the world's total fossil fuel
consumption rose 15-fold. But coal mined during the
twentieth century contained more energy than any other
fuel, about 5.5 ZJ. In contrast, the energy content of
crude oil extracted between 1901 and 2000 was about
5.3 ZJ, but during the century's second half it surpassed
that of coal by roughly one-third. China and India are
the only major producers where coal is still an important
household fuel; elsewhere it is used mostly to generate
electricity and to produce metallurgical coke and cement.
More efficient iron smelting lowered the specific use of
coke from 1.3t/t of hot metal in 1900 to less than 0.5
t/t in 2000 (Smil 1994; de Beer, Worrell, and Blok
1998). Steel recycling (some 350 Mt of the scrap metal,
an equivalent of @40% of global steel output, is now
reused annually) and direct iron reduction made blast
furnaces less important, and injection of 1 t of pulverized
coal directly into a furnace displaces about 1.4 t of cok-
ing coal (WCI 2005). Coke now needs only about 17%
of the world's extracted hard coals, or just over 600 Mt
in the year 2000 (WCI 2005). In contrast, coal use by
cement production has been increasing (more than 1.8
Gt annually since 2002, with the processing requiring
3-9 GJ/t). In 2000 it amounted to about 150 Mt,
8.5
Coal production, 1800-2005 (Smil 2003; BP 2006).
In 1900 coals accounted for about 95% of the world's
total primary energy supply (TPES). Coal's share then
declined during every year of the twentieth century, fall-
ing to below 75% by 1939 and to less than 50% by 1962.
OPEC's oil price rises of the 1970s engendered unrealis-
tic (albeit widespread) hopes of coal's comeback (Wilson
1980). Coal's share slipped to just below 30% by 1990
and to no more than 23% of the world's TPES by 2000,
but it rose to nearly 28% by 2005. While the ranks of hy-
drocarbon producers have been steadily expanding, those
of coal-mining countries have been declining. In 2000
only 16 countries extracted annually more than 25 Mt,
and the six largest producers (in the order of energy con-
tent, the United States, China, Australia, India, Russia,
and South Africa) accounted for slightly over three-
quarters of the world's output. The United Kingdom,
the world's
second largest coal producer
in 1900,
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