Environmental Engineering Reference
In-Depth Information
the time of worldwide peak extraction and the eventual
duration of the fossil fuel era. But even the most liberal
assumptions regarding ultimately recoverable resources
do not change a basic fact: the overall duration of
the fossil fuel era cannot last for many centuries. Spatial
distribution of fossil fuels is highly unequal, with three
nations (United States, Russia, and China) claiming
more than two-thirds of all coal and the Persian Gulf-
Zagros Basin storing more than half of all recoverable
hydrocarbons.
Coal's ascent was based on an enormous investment of
hard and dangerous human labor. The mechanization
of underground mining spread widely only after 1945; it
remains low in Chinese and Indian mines. Daily produc-
tivities of 0.5-2 t/miner were substantially lifted by a
gradual shift to surface mining. Its relative safety, high
coal recovery rate (
>
90% compared to 50% for the tradi-
tional room-and-pillar method), and high productivity
(
>
20 t/shift) make it superior even to long-wall extrac-
tion, the best modern underground technique. The
power densities of coal extraction range from 1-2 kW/
m
2
in underground mines to 20 kW/m
2
in large surface
operations. China, the United States, Australia, and Rus-
sia produce nearly three-quarters of global output. In
2005 only about 15% of hard coal's global extraction
was exported, but crude oil is the world's most valuable
traded commodity; 40% of its output was exported.
The slow rise of crude oil production during the late
nineteenth century, when it was used mostly for illumina-
tion and lubricants, was followed by worldwide growth
driven above all by the diffusion of internal combustion
engines and the expansion of petrochemical industries.
Improvements in drilling (cable-tool drills displaced by
rotaries, horizontal wells), transportation (extensive con-
struction of larger and longer pipelines, increased tanker
sizes peaking at just over 500,000 dwt), and processing
(larger, more efficient refineries with catalytic cracking)
made oil the world's most important source of primary
energy. Its production densities are 10-20 kW/m
2
, and
about 10% of it goes for nonenergy uses (lubricants, pet-
rochemical feedstocks). The Middle Eastern oil fields
dominate global extraction.
Outside the United States natural gas became an im-
portant fuel only after WW II, with the advent of long-
distance, large-diameter, seamless pipelines. Trunk gas
lines now connect Canada with the United States, and
Europe with Western Siberia, the North Sea, and North
Africa. Since the 1960s, LNG exports have been steadily
expanding, with Indonesia, Malaysia, Qatar, Trinidad,
and Tobago being the top exporters and Japan, South
Korea, the United States, and Spain the leading buyers.
Natural gas is also an important feedstock (above all, it
supplies H for the Haber-Bosch synthesis of ammonia
from its elements), and its cleanliness makes it the pre-
ferred choice for household and urban uses. Russia and
the United States are by far the largest producers.
Since the 1890s increasing amounts of fossil fuels
(more than 30% by the year 2000) have been used indi-
rectly as electricity. Edison's brilliant creation of a whole
new energy generation, distribution, and conversion sys-
tem started a still continuing expansion of the most con-
venient, cleanest (at the point of use), and productively
most rewarding source of energy. Growth rates of
electricity production have consistently outperformed
increases in fossil fuel extraction. Most of the installed
global capacity remains in fossil-fueled, especially coal-
fired, power plants, but almost 25% of total output
comes from hydrogeneration and nearly 20% from nu-
clear fission. Efficiencies of thermal generation rose from
5% to slightly over 40% in the best plants, long-distance
