In an integrated gasification combined cycle (IGCC) plant, the coal reacts with oxygen and steam to produce a synthesis gas that is primarily hydrogen and carbon monoxide. Carbon dioxide and other pollutants can be efficiently separated from the raw synthesis gas, which is then burned in a high-temperature gas turbine that drives an electric generator. The exhaust from the gas turbine is then piped through a heat exchanger that boils water into steam, which is used to drive a second turbine. Though 20 percent more costly to build, IGCC plants can achieve efficiencies far exceeding those of traditional coal plants. More important, they allow the carbon-dioxide waste stream to be captured.
Source: Harvard Magazine, 05-06/06
