Dirty Coal, Clean Future

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"Coal can and should be used in less damaging, more sustainable ways."



Significant Chinese developments involve more than the "clean tech" boom that Americans have already heard so much about: this involves not clean tech but the dirtiest of today's main energy sources—coal.

For the coal industry, the term "clean coal" is an advertising slogan; for many in the environmental movement, it is an insulting oxymoron. But coal can be used in less damaging, more sustainable ways than it is now, and it must be used in those ways, because there is no plausible other way to meet the world's unavoidable energy demands.

"Good ideas about climate change are not in competition with one another," Roger Aines, a climate scientist at Lawrence Livermore National Laboratory, said. "We need every possible solution, and then we need more."

What would progress on coal entail? The proposals are variations on two approaches: ways to capture carbon dioxide before it can escape into the air and ways to reduce the carbon dioxide that coal produces when burned. In "post-combustion" systems, the coal is burned normally, but then chemical or physical processes separate carbon dioxide from the plume of hot flue gas that comes out of the smokestack. This part of the exhaust is pressurized into liquid form and then sold or stored.

Yet the "parasitic load" of energy required to treat and compress the separated stream of carbon dioxide can come to over 30% of the total output of a coal-fired power plant—so even more coal must be burned to produce the same supply of electricity. Without mandatory emission limits or carbon prices, burning coal cleanly is more expensive.

"If there were a price on carbon"—a tax on carbon-dioxide emissions—"you could plug in a loss of $30 to $50 per ton, and build a business case," an electric utility executive told me.

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