By Seán Captain
Popular Science
-- Big lumps of sooty coal hardly seem like the future of energy, but that's exactly what the U.S. Department of Energy predicts. Consumption of the fossil fuel --the main source of greenhouse gas and a major contributor to acid rain, smog and mercury poisoning --will hit 10.6 billion tons a year by 2030, a near doubling of the 5.4 billion tons burned in 2003, according to the agency.
But coal's growing dominance need not spell doom for the environment, says Mike Mudd, a former manager of technology development at American Electric Power (AEP), one of the country's biggest utilities. Mudd is now CEO of FutureGen, a $1-billion project sponsored by the DOE in partnership with 11 leading energy companies to build the first near-zero-emission coal plant by 2012. The 275-megawatt facility will serve as the model for a new generation of high-tech coal facilities.
Coal contains anywhere from 25 to 90 percent carbon, which combines with oxygen when burned to release energy. This process emits a host of noxious chemicals, such as carbon dioxide, sulfur, nitrogen oxide and mercury. Yet carbon in coal can also be used to strip oxygen from water, producing clean-burning hydrogen gas. FutureGen will liberate hydrogen by heating finely ground coal in a high-pressure, pure-oxygen environment, a process known as gasification and a turbine will burn the resulting hydrogen gas to produce electricity. As for emissions, the plant will pump the CO2 underground while the other pollutants are converted to an inert solid and buried.
Gasification itself is nothing new. Cut off from petroleum imports, German engineers in World War II used the process to make synthesis gas, or syngas, a mixture of hydrogen and carbon monoxide that they converted to diesel fuel. Today, about half a dozen American plants burn syngas to generate electricity. They emit about the same amount of CO2 as conventional plants but make capturing the pollutant much easier. Of the 154 new and proposed coal plants in the U.S., 28 will use gasification.
The FutureGen plant takes gasification a step further by burning only the hydrogen from syngas. The carbon monoxide is combined with steam to produce additional hydrogen, along with CO2 that will be pumped 2,700 to 16,000 feet underground into deep saline reservoirs. The U.S. alone has the geological capacity to store up to 2.2 trillion tons of CO2, roughly 1,000 years' worth of U.S. power-plant emissions, estimates Julio Friedmann, who directs research on CO2 sequestration at Lawrence Livermore National Laboratory.
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http://www.cnn.com/2007/TECH/02/02/green.coal/index.htmlColor me skeptical. Only in the LAST para is it acknowledged that sequestration is not likely to be an effective approach for very long. The problem with sequestration which I don't see being addressed is that eventually -- slowly, but eventually -- that CO2 is gonna seep back out. And because CO2 is soluble in water, it can permeate almost any rock that water can permeate. I'll take these projections as wildly optimistic, coming from people with compromised judgement.