Environmental Engineering Reference
In-Depth Information
4
Fossil fuels—coal, petroleum, natural gas, and their by-products—account for ap-
proximately 85% of the world's primary energy needs today. Use of these fuels
drives industrialized economies and has become an integral part of every aspect of
productive activity and daily life throughout the modern world.
The resource base for gas, oil, and coal is usually split into two components:
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Reserves
, which reflect the existing quantity of each fuel, with reasonable certainty.
Reserve measurements are based on available geological and engineering data from
known reservoirs and present economic and operating conditions. The lifetime of
proven reserves (in years) is obtained by dividing the amount of reserves by the present
yearly consumption.
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Resources
, which reflect untapped sources of oil, gas, and coal and could extend the
lifetime of reserves by a factor of 5-10. The extraction of these resources involves ad-
vanced technologies, higher costs, and possibly serious environmental problems.
Between 1869 and 2006 one-half of the proven reserves of oil were consumed,
along with one-third of the natural gas reserves and approximately one-quarter of
the coal reserves.
What do we know about coal?
Coal (or mineral coal) is the generic name given to a material that is produced
when terrestrial plants, having been deposited underground a million years prior,
undergo chemical and geological processes that give rise to turf, lignite, bitumin-
ous, and anthracite coal. The fraction of carbon found in this chain of materials
increases gradually from wood (49.65%), to turf (55-44%), lignite (72.95%), bitu-
minous coal (84.24%), and anthracite (93.50%). The heat content of these different
types of fuel increases as the carbon content increases, from 4.0-4.5 kcal/kg in the
turf to 7.8-9.1 kcal/kg in anthracite.
