Carbon Capture Remains Elusive

Despite subsidies and new projects, carbon dioxide sequestration is still a long way off.

On October 1, a coal-fired plant in West Virginia operated by American Electric Power (AEP) became the first power station in the U.S. to pump a portion of its carbon dioxide emissions underground. At the same time, the U.S. Department of Energy is funneling billions of stimulus dollars into carbon capture and sequestration. And FutureGen, a government-backed project to build the first zero-emissions coal-fueled plant, looks set to rise from the ashes.

Capture this: A carbon capture and sequestration facility operated by American Electric Power and Alstom at the Mountaineer Power Plant in New Haven, WV. Credit: Alstom

At first blush, it seems carbon capture and sequestration (CCS) is on its way to making clean coal a reality. However, no commercial-scale CCS operation is near completion in the U.S., and until a market price is set on carbon dioxide, experts say things aren't likely to change.

"Until there is a market, the technology won't take off," says Howard Herzog, principal research engineer with the MIT Energy Initiative. "It's amazing that there are as many projects going on that there are today; they are all research and development projects that are funded with subsidies."

The American Recovery and Reinvestment Act of 2009 provided $3.4 billion in federal funding for CCS projects, including $1 billion for FutureGen and more than $1 billion for other commercial-scale operations. Yet even with this money, significant hurdles remain.

"There are an array of technical challenges that have to be overcome," says Tom Williams, a spokesperson for utility company Duke Energy, which recently invested $17 million in carbon-capture research at a coal gasification power plant in Edwardsport, IN, and is currently seeking federal funding to further develop capture and sequestration technology at the plant. "Permitting challenges, sequestration challenges, geological challenges, [and] efficiency challenges all have to be figured out," Williams says.

One of the geological challenges faced by Duke Energy and others investigating in CCS is ensuring that the pressure inside reservoirs deep beneath the surface of the earth doesn't climb too high as carbon dioxide is injected. "There are only certain safe levels that you can raise the pressure to before you get into issues of seismicity," Herzog says.

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Ernest Majer, a seismologist at Lawrence Berkeley National Laboratory, briefed members of the U.S. Senate in September on these potential hazards. He says that pumping pressurized, liquid carbon dioxide underground has the potential to cause minor earthquakes, although with proper site selection and injection rates, this shouldn't be an issue. "If you inject great volumes into an active fault, then yes, you are going to have problems, but we've been injecting wastewater from municipalities for years without a problem," he says. "You just have to engineer it properly."

In particular, this means implementing reliable monitoring systems to track the movement of carbon dioxide deep underground. Sensors used in oil and gas fields are well developed for this purpose, though less-expensive monitoring systems would make carbon dioxide sequestration for coal plants more cost-competitive.