WASHINGTON—Sometime this summer, a huge coal-fired power plant near the shore of Lake Michigan will try a new process to capture carbon dioxide (CO2), a powerful greenhouse gas that gushes from its smokestack.
The experiment at the We Energies plant in Pleasant Prairie, Wis., is among a batch of technologies aimed at slowing the rising tide of CO2 in the atmosphere, which scientists have concluded is a leading cause of global warming.
Half the electricity generated in the United States comes from burning coal, America's most plentiful and cheapest energy source. Unfortunately, burning coal is also a major producer of carbon dioxide, releasing an estimated 1.5 billion tons of the heat-trapping gas every year.
Experts think that much of the buildup can be avoided if CO2 is captured at power plants and stored underground or under the ocean for hundreds, even thousands, of years.
This process, known as "Carbon Capture and Sequestration," is one of the hottest fronts in the battle against global warming.
"Carbon capture and storage is central to the future of coal in the United States and our future energy policy," Sen. Jeff Bingaman, D-N.M., the chairman of the Senate Energy and Natural Resources Committee, said at a hearing March 22.
"It won't be cheap or easy," cautioned Bryan Hannegan, a vice president at the Electric Power Research Institute, a power industry organization based in Palo Alto, Calif. "It will require billions (and) a potentially large hike in consumers' electric bills."
Many technical problems remain to be solved. The Department of Energy estimates that it may be at least 2020 before carbon capture and sequestration will be economically competitive with existing plants.
The $11 million Pleasant Prairie carbon-capture pilot experiment is a joint project of EPRI and Alstom, a French manufacturer of power equipment.
The Alstom system uses chilled ammonia, a common solvent, to separate carbon dioxide from other flue gases created in the power plant. It works somewhat like the way a catalytic converter removes toxic gases in an automobile engine.
If the Wisconsin experiment succeeds, American Electric Power, a giant utility company based in Columbus, Ohio, will apply it in a much larger, $80 million demonstration project at its Mountaineer plant in New Haven, W.Va., starting in mid-2008. Up to 100,000 tons a year of CO2 captured there will be stored 9,000 feet below the ground in a nearby saltwater aquifer.
And if the West Virginia operation goes well, American Electric Power plans to open a $300 million commercial-scale carbon-capture plant in 2011 at its Northeastern Station in Oologah, Okla. That system is expected to collect 1.5 million tons of CO2 a year. The gas will be pumped into existing oil wells to raise the pressure and drive out more oil.
American Electric Power chose the chilled ammonia system because it's more efficient and costs less than other technologies, company spokesman Barry McNulty said. In EPRI's laboratory tests, the process removed up to 90 percent of the carbon dioxide and required a third as much energy as other technologies, he said.
The storage, or sequestration, of carbon dioxide captured from coal or other fuels has been under way for more than a decade.
Norway has pumped millions of tons of CO2 collected from a natural gas field into an aquifer below the North Sea. Algeria reinjects CO2 from its Salah gas field into an underground geologic formation. The Great Plains Synfuels coal-gasification plant in Beulah, N.D., captures a million tons a year of CO2 and pipes it 200 miles to spur oil production at the Weyburn oil field in Saskatchewan, Canada.
"These three projects together sequester 3 to 4 million tons of CO2 per year, about as much as one typical 500-megawatt coal-fired plant," Hannegan told the Senate committee. "With 17 collective years of operating experience, these projects suggest that CO2 storage in deep geologic formations can be carried out safely and reliably."
EPRI estimates that the United States has enough underground storage capacity to hold several centuries' worth of carbon dioxide emissions from coal-burning power plants.
The rising interest in carbon capture and storage is a response to mounting public awareness and concern about global warming. The Democratic-controlled Congress is showing new interest in legislation promoting or requiring CO2 reductions. Former Vice President Al Gore told Congress recently that it should "freeze" carbon emissions immediately.
The coal-power industry is reading the handwriting on the wall.
"The potential for future regulations on CO2 emissions prompted We Energies to indicate interest in supporting development of promising carbon-capture technologies," McNulty said.
"With Congress expected to take action on greenhouse-gas issues in climate legislation, it's time to advance this technology for commercial use," Michael Morris, American Electric Power's chief executive officer, has said.
"It's very clear to us which way the policy debate is going on this," American Electric Power spokesman Pat Hemlepp said. "It's going to accelerate this technology and its commercial applications."
An MIT Web site on carbon capture and sequestration: http://sequestration.mit.edu