Cleaner Coal Is Attracting Some Doubts

Environmentalists are worried, but they put their faith in a technology that gasifies the coal before burning. Such plants are designed, they say, to be more adaptable to separating the carbon and storing it underground.

Most utility officials counter that the gasification approach is more expensive and less reliable, but they say there is no need to worry because their tried-and-true method, known as pulverized coal, can also be equipped later with hardware to capture the global warming gas.

But now, influential technical experts are casting doubts on both approaches.
A major new study by faculty members at the Massachusetts Institute of Technology, scheduled for release soon, concludes in a draft version that it is not clear which technology — the so-called integrated gasification combined cycle or pulverized coal — will allow for the easiest carbon capture, because so much engineering work remains to be done.

Retrofitting either a gasification or pulverized coal power plant is not just a matter of adding new equipment and it might be impractical, the experts say. Temperatures and pressures would be designed to be in one range for a plant that captured its carbon, and another if it merely produced electricity with minimum use of fuel. Less fuel means less carbon dioxide production.

Adding carbon capture later also has implications for power supply. Early estimates are that carbon capture will require so much energy that it could reduce plant output by 10 to 30 percent.

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