A combined-cycle power plant combines a gas turbine and a steam turbine to generate up to 50% more energy from the same fuel as a standard simple-cycle plant. The gas turbine's waste heat is directed to a neighboring steam turbine, which provides additional electricity. The gas and steam turbines are mounted on one shaft that can be separated for maintenance purposes.
Gas turbines use the heat of the exhaust gas after combustion to create steam that drives a separate steam turbine. So instead of using ambient air as a source of heat, which would be very inefficient, most gas turbines use the heat of the exhaust gas after combustion to make hot water or steam which is then used to drive a steam turbine. The gas turbine doesn't need any outside air to burn fuel, so it can run continuously without stopping for air pollution controls.
Combined-cycle plants are commonly used in power generation facilities because they produce more energy per unit of fuel than simple-cycle plants. They also emit less carbon dioxide than their simple-cycle counterparts. However, combined-cycle plants do use more steel than simple cycles, especially for large sizes.
A combined-cycle power system generally drives an electrical generator with a gas turbine and recovers waste heat from the turbine exhaust to create steam. To generate additional power, waste heat steam is routed via a steam turbine. Thus, combined-cycle systems can be thought of as having two interconnected gas turbines that drive two separate generators.
The first commercial gas turbine was built by MIT professor Frank K. Stultz and his team in 1951. It used liquid fuel and generated 25 kilowatts (kw) of power. The second machine was developed by Westinghouse in 1958 and it used natural gas and produced up to 100 kw. Since then, many improvements have been made to gas turbines for use in power generation. Today's gas turbines can produce up to 500 kw or more. They are often used in conjunction with other components such as heaters, steam generators, or compressors to provide electricity at locations where there is not enough wind or solar energy to operate a pure electric generator.
Gas turbines are very efficient tools for generating power because they can run on almost any type of fuel, including coal, oil, or nuclear material. This makes them suitable for use in remote areas where there is no access to renewable energy sources like sun and wind. Additionally, gas turbines cause less air pollution than other types of engines.
Gas turbine plants often have a lower footprint than engine-based power facilities. Finally, gas turbine combined cycle facilities may benefit from any site being integrated into industrial districts by selling steam to surrounding enterprises. These factors should be considered in selecting the type of facility needed for each application.
Fossil fuel power plants burn their fuel to generate thermal energy, which is then used to power its external heat engines. A simple cycle gas plant, unlike the others, does not use steam; instead, it operates similarly to a jet engine, where natural gas is ignited and burnt, creating pressure that powers the turbine. This in turn generates electricity.
The term "fossil fuel" refers to any rock or biological material that has been converted by time into oil or natural gas. Fossil fuels are formed over hundreds of years through decomposition of dead organisms such as trees, plants, and animals. They are stored inside their original form in the ground, and only become available when we dig them up. Oil and natural gas wells produce between 1 and 10 million barrels of oil or 1 billion cubic feet of natural gas at once. Mining produces even more massive amounts - 5 to 50 million barrels or 100 to 1000 million cubic feet at a time. Coal deposits range from thousands to millions of years old, and are found everywhere in the world except Antarctica. It takes about 500 years for coal to completely decay, so they provide a constant source of energy throughout human history.
Oil was first discovered in Egypt around 5500 B.C., and natural gas was found around 250 B.C. Today, almost all global energy production comes from fossil fuels, with the exception of solar and wind power. Solar panels can convert light energy from the sun into electrical energy, but they cannot create energy out of nothing!
The boiler's heat converts the water into steam. The steam turbine is turned by the steam pressure, and the generator creates energy. A combined-cycle power plant produces gas initially by burning fuel in compressed air. The gas turbine is rotated by the pressure of the gas, and the generator generates power. Combined-cycle plants use gas more efficiently than other types of generators because they are able to produce more electricity from each pound of oil or each kilowatt hour of electricity generated.