U.S. Department of Energy - Energy Efficiency and Renewable Energy

Advanced Manufacturing Office – Industrial Distributed Energy

Industrial Gas Turbines

Mercury 50 Cutaway Illustration

Cutaway Illustration of Mercury 50 Recuperated Gas Turbine, Courtesy of Solar Turbines

A gas turbine is a heat engine that uses high-temperature, high-pressure gas as the working fluid. Part of the heat supplied by the gas is converted directly into mechanical work. High-temperature, high-pressure gas rushes out of the combustor and pushes against the turbine blades, causing them to rotate. In most cases, hot gas is produced by burning a fuel in air. This is why gas turbines are often referred to as "combustion" turbines. Because gas turbines are compact, lightweight, quick-starting, and simple to operate, they are used widely in industry, universities and colleges, hospitals, and commercial buildings.

Simple-cycle gas turbines convert a portion of input energy from the fuel to electricity and use the remaining energy to produce heat, which is normally rejected to the atmosphere. However, this waste heat can be used to create steam to power a separate turbine. The attached steam turbine can generate electricity or power a mechanical load. This is referred to as combined-cycle combustion because two processes or cycles are derived from one fuel input to the primary turbine.

Simple-cycle (i.e., without external use of exhaust heat) efficiencies range from 21% to 40%. However, turbines produce high-quality heat that can generate steam for combined-cycle or cooling, heating, and power applications and enhance efficiency. These systems capture and use the heat produced in the combustion process for steam, hot water, or thermally activated equipment such as absorption chillers. Taking advantage of the normally wasted heat means a tremendous gain in efficiency—nearly 90% in some cases.

For information about current DOE efforts in this technology area, please visit the Research and Development page.

For information about DOE accomplishments in this technology area over the last decade, please see Combined Heat and Power: A Decade of Progress, A Vision for the FuturePDF.