Many of the new natural gas fired power plants are what are known as “combined-cycle” units. In these types of generating facilities, there is both a gas turbine and a steam unit, all in one. The gas turbine operates in much the same way as a normal gas turbine, using the hot gases released from burning natural gas to turn a turbine and generate electricity.
In combined-cycle plants, the waste heat from the gas-turbine process is directed toward generating steam, which is then used to generate electricity much like a steam unit.
Because of the efficient use of heat energy released from natural gas, combined-cycle plants are much more efficient than gas turbines alone. In fact, combined-gas plants can achieve thermal efficiencies of up to 50 percent to 60 percent.
John Anspach, Logansport
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