The benefits of reusing captured heat
Coal-fired power plants produce half the electricity in the U.S. and account for about 75 percent of total power generation in China, which leads the world in coal consumption. At a coal-fired plant, finely ground coal is mixed with air and burned in a boiler, or furnace, where it heats water in the boiler pipes into steam that spins turbines to generate electric current. Meanwhile, carbon from the coal reacts with oxygen in the air to form CO2, which exits the power plant with the flue gas and enters the atmosphere.
Carbon-capture technologies separate CO2 from the flue gas and the CO2 is then compressed to high pressure. Compressed CO2 can be transported by pipeline and is currently used to help extract oil from underground reservoirs in a process known as enhanced oil recovery. Scientists are also evaluating the feasibility of injecting compressed CO2 one or two miles below the earth's surface into saline aquifers whose geological features would sequester the CO2 underground.
The goal of the current ERC project, says Levy, is to recover heat that is generated when CO2 is compressed and to use that heat to improve the efficiency of the power plant's operation.
"It requires a tremendous amount of pressure, about 2,200 pounds per square inch or close to 150 atmospheres, to compress CO2 to a supercritical state," says Levy. "In the compression process, CO2 heats up, creating the potential for heat to be recovered and used beneficially within the
|Contact: Kurt Pfitzer|