Energy - Environmental Science - page 297

China has enough proven coal reserves to last 300
years at its current rate of consumption. According to
the U.S. Geological Survey, identified U.S. coal re-
serves should also last about 300 years at the current
consumption rate, and unidentified U.S. coal resources
could extend those supplies for perhaps another 100
years, although at a higher cost. If U.S. coal use should
increase by 4% per year—as the coal industry pro-
jects—the country's proven coal reserves would last
only 64 years.

T rade-Offs

Coal

Advantages Disadvantages

Ample supplies
(225-900 years)

Very high
environmental
impact

High net energy
yield

Severe land
disturbance, air
pollution, and
water pollution

Trade-Offs: Advantages and Disadvantages
of Coal
Coal is the most abundant fossil fuel, but compared to
oil and natural gas it is not as versatile, has a much
higher environmental impact, and releases more
carbon dioxide into the atmosphere.
Figure 13-15 lists the advantages and disadvantages
of using coal as an energy resource. Bottom line:
Coal is the world's most abundant fossil fuel, but
mining and burning coal has a severe environmental
impact on the earth's air, water, and land, and ac-
counts for more than one-third of the world's annual
CO 2 emissions.
Each year in the United States alone, air pollutants
from coal burning kill thousands of people prema-
turely (estimates range from 65,000 to 200,000), cause
at least 50,000 cases of respiratory disease, and result
in several billion dollars of property damage. Many
people are unaware that burning coal is responsible
for one-fourth of atmospheric mercury pollution in the
United States, and it releases far more radioactive par-
ticles into the air than normally operating nuclear
power plants.
Many analysts project a decline in coal use over
the next 40-50 years because of its high CO 2 emissions
(Figure 13-10) and harmful health effects, and the
availability of safer and cheaper ways to produce elec-
tricity such as wind energy and burning natural gas in
gas turbines.

Low cost (with
huge subsidies)

High land use
(including mining)

Well-developed
mining and
combustion
technology

Severe threat to
human health

High CO 2
emissions
when burned

Air pollution can
be reduced with
improved
technology (but
adds to cost)

Releases
radioactive
particles and toxic
mercury into air

Figure 13-15 Trade-offs: advantages and disadvantages of
using coal as an energy resource. Critical thinking: pick the
single advantage and disadvantage that you think are the most
important.

Solid coal can be converted into synthetic natural gas
(SNG) by coal gasification or into a liquid fuel such as
methanol or synthetic gasoline by coal liquefaction.
Figure 13-16 (p. 298) lists the advantages and disad-
vantages of using these synfuels.
Without huge government subsidies, most ana-
lysts expect synfuels to play a minor role as energy re-
sources in the next 20-50 years. Compared to burning
conventional coals, they require mining 50% more coal
and their production and burning add 50% more car-
bon dioxide to the atmosphere. Also, they cost more to
produce than coal.
Currently, the DOE and a consortium of major oil
companies are working on ways to reduce CO 2 emis-
sions during the coal gasification process. If these ef-
forts prove successful, burning gasified coal could be a
cheaper and cleaner way to produce electricity than
burning coal, oil, or natural gas. Stay tuned.

x

H OW W OULD Y OU V OTE ? Should coal use be phased out
over the next 20 years? Cast your vote online at http//:biology
.brookscole.com/miller11.

Trade-Offs: Advantages and Disadvantages
of Converting Solid Coal into Gaseous and
Liquid Fuels
Coal can be converted to gaseous and liquid fuels that
burn cleaner than coal, but the costs are high, and
producing and burning them add more carbon
dioxide to the atmosphere than burning coal.