Keeping Coal Power, Burying the Gases: Utilities' Answer to Global Warming Faces Obstacles in N.C

By John Murawski, The News & Observer, Raleigh, N.C.

The quest to build an eco-friendly coal-fired power plant is going underground.

Duke Energy plans to pump carbon dioxide more than a half-mile deep in Kentucky next year. The demonstration will be one of two dozen across the country managed by the U.S. Department of Energy to test whether the greenhouse gas can be stored safely beneath the Earth's surface until the end of time.

Finding a safe way to dispose of carbon dioxide would essentially turn coal into an environmentally harmless fuel. The emerging technology represents industrial society's best chance of continuing to generate electricity from the nation's vast coal reserves -- which contain enough fuel for at least two centuries -- without superheating the planet.

The undertaking reflects an emerging conundrum of the technological era: producing enough affordable energy while balancing the social cost of protecting the environment.

Coal is abundant, cheap and on the verge of a major buildout. Last week, state regulators approved Duke Energy's request to build a coal-fired plant west of Charlotte. Coal produces half of the electricity used in the state and is expected to be the energy mainstay well into the century.

But even if the carbon gas can be permanently trapped deep underground, the prospects for so-called carbon sequestration in North Carolina are challenging.

Much of the state sits atop land that won't absorb carbon dioxide. Some subterranean formations could soak up the carbon dioxide, but lack a solid barrier to keep the chemical from leaking back out to the surface.

Electric utilities such as Progress Energy of Raleigh and Duke Energy of Charlotte would have to transport carbon dioxide from local power plants over several hundred miles of pipeline to deposit it offshore or outside of the state. That is, assuming consumers would be willing to pay the premium cost and that other states would accept North Carolina's waste gas.

On top of new multibillion-dollar power plants to meet rising energy demand, carbon sequestration would probably raise the state's cheap electricity rates, which are about 20 percent below the national average.

Report due next week

The Southeastern Regional Carbon Sequestration Project, an effort coordinated by the U.S. Department of Energy that includes Progress Energy and Duke Energy, is expected to issue a report on coal sequestration and its projected costs as soon as next week.

Still in its infancy, a carbon sequestration component for cleaning up power plants could increase the cost of the electricity generated by those plants as much as 80 percent, according to the Electric Power Research Institute, an industry trade group.

The goal of the federally sponsored carbon dioxide sequestration project is to bring down the cost of disposing of gases to affordable levels.

"Trying to do just a single power plant with a 200- to 300-mile pipeline would be absolutely cost-prohibitive," said Gerald Hill, a senior technical adviser on the Southern States Energy Board, one of the members of the project. "Doing a network with several plants is still very costly and gets into the billions of dollars."

The permanent disposal of carbon dioxide would become feasible only under a national policy that taxed or otherwise penalized carbon dioxide emissions and created an incentive for utilities to curb emissions, Hill said.

Retrofitting coal-fired plants would be more costly than building power plants that would capture carbon dioxide.

A new technology

Only three power plants in the world separate carbon dioxide and pump it underground on a commercial scale; the first in Norway started in 1996.

Yet the gas has been separated for decades for oil exploration. More than 70 facilities in this country pump carbon dioxide into the Earth as a way of displacing crude oil and bringing it to the surface. But in this application, no verification is required that the gas remains underground because the purpose is only to dislodge oil.

In carbon sequestration, the gas is pumped under high pressure as a liquid. Duke Energy will monitor the carbon gases in Kentucky for two to three years to determine if it remains trapped. The verification is done with sonar imaging.

Duke Energy will deposit about 10,000 tons of carbon dioxide over three to four months about 2/3-mile deep at the East Bend Generating Station, an amount equivalent to one day's emissions by the power plant. Because removing carbon dioxide from coal plant emissions is costly, Duke Energy is buying the gas from another source and trucking it to the power plant for the deep injection experiment.

Carbon sequestration would trap as much as 90 percent of greenhouse gases, but could have negative consequences for the environment by encouraging coal mining.

Dave Hamilton, the Sierra Club's director of global warming and energy programs, said the environmental organization is "agnostic" on the process. "We've never tried to do it on this kind of scale," he said. "We've never tried to monitor it to make sure the carbon doesn't move for centuries."

If the gas were to leak over time, it would not pose an immediate health hazard to humans and animal life. Leakage would represent a major waste of resources devoted to separating the gas, shipping it by pipeline and injecting it underground -- all to no avail.

"I don't think it's dangerous," UNC-Wilmington geology professor Paul Thayer said. "It's a lot more dangerous to warm up the atmosphere and cause global warming."

Staff writer John Murawski can be reached at (919) 829-8932 or murawski@newsobserver.com.

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Copyright (c) 2007, The News & Observer, Raleigh, N.C.

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