A combined cycle gas turbine uses both a gas and a steam turbine together to produce up to 50 percent more electricity from the same fuel than a traditional simple-cycle plant. The waste heat from the gas turbine is routed to the nearby steam turbine, which generates extra power.

Gas turbine burns fuel. The gas turbine compresses air and mixes it with fuel that is heated to a very high temperature. The hot air-fuel mixture moves through the gas turbine blades, making them spin. The fast-spinning turbine drives a generator that converts a portion of the spinning energy into electricity.

A Heat Recovery Steam Generator captures exhaust heat from the gas. The Heat Recovery Steam Generator creates steam from the gas turbine exhaust heat and delivers it to the steam turbine.

The steam turbine sends its energy to the generator drive shaft, where it is converted into additional electricity.