One key to a turbine's fuel-to-power efficiency is the temperature at which it operates. As large frame turbines have higher power outputs, they can produce larger amounts of emissions, and must be designed to achieve low emissions of pollutants, such as NOx. Aeroderivative engines tend to be very compact and are useful where smaller power outputs are needed.

Aeroderivative engines are derived from jet engines, as the name implies, and operate at very high compression ratios (typically in excess of 30). Pressure ratio is the ratio of the compressor discharge pressure and the inlet air pressure. Heavy frame engines are characterized by lower pressure ratios (typically below 20) and tend to be physically large.

Land based gas turbines are of two types: (1) heavy frame engines and (2) aeroderivative engines. The rotating blades perform a dual function: they drive the compressor to draw more pressurized air into the combustion section, and they spin a generator to produce electricity. As hot combustion gas expands through the turbine, it spins the rotating blades. The turbine is an intricate array of alternate stationary and rotating aerofoil-section blades.The combustion produces a high temperature, high pressure gas stream that enters and expands through the turbine section. The mixture is burned at temperatures of more than 2000 degrees F.

The combustion system, typically made up of a ring of fuel injectors that inject a steady stream of fuel into combustion chambers where it mixes with the air.

The compressor, which draws air into the engine, pressurizes it, and feeds it to the combustion chamber at speeds of hundreds of miles per hour.

The combustion (gas) turbines being installed in many of today's natural-gas-fueled power plants are complex machines, but they basically involve three main sections:

Gas station steam