The Dirty Secret -- Critique of FutureGen Coal Plant etc.
Technology Review: The Dirty Secret, July/August 2006
Today there is a patch of land in Great Bend, OH, where an advanced coal plant may one day be built. The plant could eventually include equipment for siphoning off carbon dioxide. But it's not FutureGen, which today remains a collection of research projects. No FutureGen plant has been constructed, and no site for one has been chosen. The proposed plant at Great Bend could more appropriately be called "PresentGen." The technology involved doesn't demand a White House neologism suggesting that clean coal is something for which we must wait.
If IGCC is more than ready, its benefits are apparent, and sequestration seems plausible, why aren't plants that at least make carbon dioxide capture simpler getting built? "I don't necessarily think the technology is the limiting step. What's not there is the economic incentive, of course," says Howard Herzog, a chemical engineer at MIT, who manages an industrial consortium called the Carbon Sequestration Initiative. AEP estimates that IGCC plants with carbon sequestration could carry a 50 percent overall cost premium compared with traditional plants.
To date, pumping carbon dioxide underground has mainly been a way to push more oil to the surface; the primary objective wasn't really to store carbon dioxide permanently. So a critical question remains unanswered: will carbon dioxide stay where you want it?
In an old steel-walled lab at Los Alamos National Laboratory in New Mexico, geochemist George Guthrie holds out a smooth chunk of cement the size of a sea scallop. The chunk was recently drilled out of cement poured more than 50 years ago to plug the pipe in an old Texas oil well that had been crammed with carbon dioxide to enhance oil recovery. Guthrie holds up the chunk: a quarter-inch swath of it is the color of an orange Creamsicle. This staining, Guthrie says, is acid corrosion induced by carbon dioxide, which forms carbonic acid when it mixes with groundwater.
The chunk is a kind of Rorschach test. On the one hand, it could be read to imply that the carbon dioxide damaged the cement plug. On the other hand, it might imply that the damage was minimal -- and may not progress further. There's a lot riding on the answer. If the plug on a reservoir blew, the carbon dioxide could be released -- and the climate benefits of sequestration would, as it were, vanish into thin air. "There are significant consequences for doing this wrong," Guthrie observes. "On the other hand, it may be that much of the technology for doing this right already exists. There has been such enthusiasm behind [sequestration] that it is easy to forget about the implications of doing this on such a large scale."
There is reason for guarded optimism. The Statoil project and the Dakota gasification plant have already stored 20 million tons of carbon dioxide each; a gas field in Algeria has stored 17 million tons; a project in the Netherlands, eight million. The U.N.'s Intergovernmental Panel on Climate Change estimates -- based on experience and on models -- that properly engineered systems could retain 99 percent of their carbon dioxide over 100 years and would "likely" do so over 1,000 years.