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Half of U.S. electricity
generation comes from coal. Another
fossil fuel is natural gas, which contributes another 20%. Nuclear and hydro
account for nearly all of the rest, with renewables such as wind, solar,
geothermal, tidal, etc., combined contributing less than 1%.
There are good reasons why coal
is king, and will continue to be dominant in the future. America is the Saudi Arabia of coal, with
enough to last 250 years. Coal can
produce power whenever it is needed, unlike wind or solar. Natural gas is more expensive than coal on a
dollars per btu basis, and it is required for home heating and other uses. Nuclear is unpopular, due to events like
Three Mile Island and Chernobyl, and the unsolved problem of nuclear waste disposal. The estimated cost of new nuclear capacity is
over $5,000 per kilowatt (kW, or thousands of watts). That’s much more than the cost of even the
most expensive coal plant (Integrated Gasification Combined-Cycle, IGCC) at
$3,500/kW. Hydro is also unpopular, and
no good damsites remain. Renewables are
negligible, considering the huge demand of America for power and the small
capacity of wind and solar to meet that demand.
Per capita electricity
consumption in the United States is 33 kilowatts per day. Despite conservation efforts, living the
American dream requires more electricity consumption each year. Electric or hydrogen cars would increase the
power demand, and the need for coal.
Nevertheless, of the 12,000 MW
(megawatts, or millions of watts) of coal-fired power capacity announced in
2002 as expected to be ready by 2005, only 329 MW became reality, as reported here.
Part of the reason for tardy
deployment of coal plants is increasing concern about emissions. In 2006, coal plants emitted 2,121 million
metric tons of carbon dioxide (CO2). A
typical 250-MW coal-fired electric power plant emits 1.7 million metric tons of
CO2 a year. Each metric ton (a thousand
kilograms, or a million grams) is about the size of a house, i.e. the volume of
a cube 8.2 meters on a side. So this is
a huge stream to be captured and somehow made harmless.
And that’s only the carbon
dioxide in the emission stream (flue gas) – other pollutants include nitrogen
oxides (NOx), sulfur oxides (SOx), mercury, and fly ash. Environmental regulation is becoming very
tight and punitive. With global
climate change a frightening reality, and the need for a coal plant to scrub large volumes of CO2 as well as these other pollutants,
nobody wants to invest in coal plants.
Since CO2 scrubbing technology is unproven, the cost is unknowable, the
risk to investors is therefore incalculable.
Natural gas plants, although
they don’t have the NOx, SOx, and fly ash problems of coal plants, are also
heavy greenhouse gas polluters. In 2006,
natural gas plants dumped 1,169 million metric tons of CO2 into America’s
atmosphere.
The world needs coal power, but
the hang-up is flue gas scrubbing. So
that is where our ingenuity and resources need to be focused in the near
term.
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