Environmental Engineering Reference
In-Depth Information
perial Oil's Cold Lake Project, uses injections of hot,
pressurized steam (300
C, 11 MPa) to recover about
25%, and with follow-up processes up to 35%, of the bi-
tumen present in sands (Lui 2004). Another large-scale
nonconventional operation is the extraction of bitumen
from the enormous deposits in the Orinoco Belt. The
final product, 70% natural bitumen, 30% water, and a
small amount of an additive that stabilizes the emulsion,
is sold as liquid Orimulsion by Petr
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leos de Venezuela
(PDVSA 2001).
At the beginning of 2005 total conventional reserves
of the three principal fossil fuels added up to about 31
ZJ, with coals accounting for about 60% of the total and
hydrocarbons 40%. A gradual shift of some nonconven-
tional oil and gas resources into the recoverable category
(already under way with heavy oils, oil sands, and coalbed
methane) could substantially increase the hydrocarbon
share. The continental division of fossil fuel reserves
shows Asia's lead, with nearly 50% of the global total,
and Africa's less than 10%. In per capita terms, Russia
has the largest reserves among the major economies, and
China, because of its large population, the smallest.
and gas began to contribute more than one-half of the
world's fossil fuels output, their extraction began to shift
increasingly offshore.
Coal extraction remained muscle-powered and very
risky until the early twentieth century. Traditional meth-
ods were first replaced by handheld pneumatic hammers,
then by mechanized cutters and loaders, and finally by
continuous miners, machines that grind coal from the
face and dump it on an adjoining belt. In 1920 all U.S.
coal mined underground was manually loaded into mine
cars, but by the 1960s nearly 90% was machine-loaded
(Gold et al. 1984). The most economical and safest
method of underground extraction is longwall mining,
introduced during the 1960s (Ward 1984; Barczak
1992). This technique uses large drum-shaped shearers
to cut panels up to 2.5 m high, 80-200 m wide, and up
to 1.5 km long that are delimited by two side tunnels.
Miners remain always under a protective canopy of hy-
draulic steel supports, which are advanced and reset as a
face is completed, leaving the unsupported roof behind
to cave in (fig. 8.4). This technique recovers more than
90% of coal compared to just 50% in room-and-pillar op-
eration, and it now accounts for just over half of U.S. un-
derground extraction (EIA 2006b).
The largest coal production increase came from new
large-scale opencast operations in the United States,
Russia, Australia, and China. By the year 2000 the largest
of these mines produced annually more coal that did the
entire formerly prominent coal-mining nations from their
underground seams. With nearly 75 Mt a year mined
in 2004, the Powder River Coal Company's North
Antelope/Rochelle mine in Wyoming extracted more
solid fuel than did the Ukraine, the world's tenth largest
bituminous coal producer (EIA 2005c). Much better
overall safety and the virtual elimination of traditional
8.3 From Extraction to Combustion: Modern
Fossil Fuel Industries
Modern extraction, transportation, and processing of
fossil fuels are characterized by an extraordinarily high
degree of mechanization, which makes it possible to pro-
duce and distribute enormous masses of solids, liquids,
and gases at affordable prices. Fossil fuel industries are
among the least labor-intensive sectors of modern econo-
mies; their activities and markets are truly global; and
their ability to deliver energy at a low, often declining
real cost underpins the current high-energy civilization.
Coal dominated globally until the early 1960s, and as oil
