Combined cycle power plants typically feature a gas turbine that generates electricity using natural gas as a fuel, as well as a steam turbine that generates electricity using the waste heat from the gas turbine as its fuel. This configuration is very efficient, since it re-uses exhaust heat that would otherwise simply be released into the air.
A gas turbine compresses air and mixes it with fuel. The fuel is burned and the hot air-fuel mixture is expanded through turbine blades, making them spin. The spinning turbine drives a generator which converts the spinning energy into electricity.
- Fuel is burned in the gas turbine
- The resulting energy in the gas turbine turns the generator drive shaft
- Exhaust heat from the gas turbine is sent to a heat recovery steam generator (HRSG)
- The HRSG turns the gas turbine exhaust heat into steam and feeds it to the steam turbine
- The steam turbine delivers additional energy to the generator drive shaft
- The generator converts the energy into electricity
A steam turbine converts the thermal energy in steam to rotational movement. Steam strikes the
blades of a turbine, causing the turbine to rotate in the same way wind causes a windmill to turn.
The rotating turbine shaft drives a generator. Inside the generator, a spinning magnet surrounded by
coils of copper wire creates a magnetic field which charges electrons in the copper wire and produces
electricity.