Environmental Engineering Reference
In-Depth Information
roads.
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Coal-burning power plants are the major cause of global warming
and should be replaced as soon as possible. Coal power plants are the
least carbon-effi cient power stations in terms of the level of carbon
dioxide produced per unit of electricity generated.
“Clean Coal”
Coal producers and industries that rely on coal have for some years been
promoting a concept they call “clean coal.” There is no such thing. Coal
is inherently a dirty fuel, and there is no way to make it clean at any
acceptable cost. As Al Gore put it in 2008, “Clean coal is like healthy
cigarettes.”
Clean coal is a theoretical concept whereby the carbon dioxide pro-
duced by the burning coal is captured and disposed of so it does not
enter the atmosphere. Conventional pulverized coal plants burn coal in
air, producing an effl uent composed of 80 percent nitrogen, 12 percent
carbon dioxide, and 8 percent water. The carbon dioxide can be chemi-
cally separated from the nitrogen, then extracted and compressed for
injection into storage locations. This uses energy—roughly 30 percent of
the energy from burning the coal in the fi rst place—and may raise the
cost of generating electricity from coal by 50 percent.
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As of the end of
2009, there were no operating clean coal commercial power plants in
existence, although a small pilot plant started operating in eastern
Germany in September 2008.
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The carbon dioxide will be captured,
liquefi ed, and transported by truck 150 miles from the plant to be
injected 10,000 feet underground into a depleted gas fi eld. Ideally, in the
future, the gas will be carried by pipeline to underground storage. Vaclav
Smil of the University of Manitoba, Canada, has calculated that handling
and transporting just 10 percent of today's carbon dioxide emissions
would require more pipelines and other equipment than is now used
worldwide to extract oil from the ground.
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The storage reservoir proposed by the coal enthusiasts is the subsur-
face. Simply pump the carbon dioxide below ground where, the coal
companies believe, it will remain indefi nitely. Unfortunately, subsurface
injection has been used legally for many years to dispose of toxic waters
produced by oil refi neries and chemical plants, and the result has been
aquifer contamination in at least twenty-fi ve states. The geology of rocks
in the subsurface can never be known well enough to ensure that leakage
will not occur.
And then there is economics. On January 30, 2008, the administration
of President George W. Bush announced it was terminating a joint project
