Power plants - Definition


Power plants - Definition

For other uses, see Power station (disambiguation).

A power station (also power plant) is a facility for the generation of electric power. The term is also used to refer to the engine in ships, aircraft and other large vehicles.

At the center of nearly all power stations is a generator, a rotating machine that converts mechanical energy into electrical energy by creating relative motion between a magnetic field and a conductor. The energy source harnessed to turn the generator varies widely from installation to installation.

In thermal power plants mechanical power is produced by a heat engine, which transforms thermal energy, often from combustion of a fuel, into rotational energy. All thermal energy can not be transformed to mechanical power, according to the second law of thermodynamics. Therefore, thermal power plants also produce low-temperature heat. If no use is found for the heat, it has to be rejected. If reject heat is employed as useful heat, the power plant is referred to as a cogeneration power plant or CHP (combined heat-and-power) plant.

Nuclear power plants use a nuclear reactor as the source of heat.

Thermal power stations are often easily identified by cooling towers, huge cylindrical chimney-like structures that release the waste heat to the atmosphere.

Other power stations use the energy of water (waves, tides, or rivers confined by hydroelectric dams), wind, or sunlight.

A pumped storage hydro power plant is a net consumer of energy but increases the value of electricity. Water is pumped to a high reservoir during the night when demand for electricity is low. During hours of peak demand, the stored water is released to produce electric power.

A solar photovoltaic power plant converts sunlight directly into electrical energy, which may need conversion to alternating current for transmission to users. This type of plant does not use rotating machines for energy conversion.

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