The Turbines of Tomorrow
Combustion (gas) turbines are key components of advanced systems designed for new electric power plants in the United States. With gas turbines, power plants will supply clean, increasingly fuel-efficient, and relatively low-cost energy.
Typically, a natural gas-fired combustion turbine-generator operating in a "simple cycle" converts between 25 and 35 percent of the natural gas heating value to useable electricity. Today, most new smaller power plants also install a recuperator to capture waste heat from the turbine's exhaust to preheat combustion air and boost efficiencies. In most of the new larger plants, a "heat recovery steam generator" is installed to recover waste heat in the exhaust to generate steam for a steam turbine-generator. This configuration is called a "combined cycle."
In 1992, the U.S. Department of Energy's Fossil Energy program began an intensive effort to break through technical barriers that had essentially capped gas turbine efficiencies. Within eight years, this program produced turbine systems that could operate at temperatures in excess of 2600 degrees F (300 degrees hotter than conventional turbines) and achieve efficiencies above 60 percent, a mark once thought unachievable. At the same time, new combustion techniques were developed to limit the formation of nitrogen oxide (NOx) emissions (the principal air pollutant released by gas turbines). As a result, high-efficiency natural gas turbines continue to be among the cleanest ways to generate electricity from fossil fuels. Gas turbines being developed under the Department of Energy's Fossil Energy Program will be able to achieve high efficiencies with NOx emissions at less than 2 parts per million.
The use of gases produced from coal as gas turbine fuel offers an attractive means for efficiently generating electric power from our Nation's most abundant fossil fuel resource. The adaptation of gas turbine technologies to use with fuels produced from coal gasification has been demonstrated under the Clean Coal Technology Program (specifically, the Tampa Electric's Polk Station and the Wabash River Repowering Projects).
The Department of Energy's Fossil Energy Program is developing key technologies that will enable advanced turbines to operate cleanly and efficiently when fueled with coal derived synthesis gas and hydrogen fuels. Developing this turbine technology is critical to the creation of near-zero emission power generation technologies.
The Federal turbine R&D program is an investment in secure U.S. electric power production that is clean, efficient, affordable and fuel flexible, and will make possible the continued use of coal--our Nation's largest domestic fossil energy resource.