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Power plants

A power station is an industrial facility for the generation of electric power. Most power stations contain one or more generators, a rotating machine that converts mechanical power into electrical power. The relative motion between a magnetic field and a conductor creates an electrical current. The energy source harnessed to turn the generator varies widely. Most power stations in the world burn fossil fuels such as coal, oil, and natural gas to generate electricity. Others use nuclear power, but there is an increasing use of cleaner renewable sources such as solar, wind, wave and hydroelectric.

According to the kind of energy used by the prime mover, power plants are divided into groups. Thermal, hydraulic (water-power) and wind plants form these groups.

According to the kind of prime mover, electric power plants are classed as: a) Steam turbine plants, where steam turbines serve as prime movers. The main generating units at steam turbine plants are the turbo generators. Steam turbine plants belong to the modern, high-capacity class of power plants.

b) Steam engine plants, in which the prime mover is a piston type steam engine. Nowadays no large generating plants of industrial importance are constructed with such prime movers. They are used only for local power supply.

c) Diesel-engine plants in them diesel internal combustion engines are installed. These plants are also of small capacity, they are employed for local power supply.

d) Hydroelectric power plants employ water turbines as prime movers. Therefore they are called hydro turbine plants. Their main generating unit is the hydro generator.

In thermal power stations, mechanical power is produced by a heat engine that transforms thermal energy, often from combustion of a fuel, into rotational energy. Most thermal power stations produce steam, so they are sometimes called steam power stations. The efficiency of a thermal power cycle is limited by the maximum working fluid temperature produced. Steam turbines generally operate at higher efficiency when operated at full capacity.

Hydroelectric power plants are built on rivers. Large-capacity hydroelectric power plants are commonly located at considerable distances from the consumers of electric power. In a hydroelectric power station water flows through turbines using hydropower to generate hydroelectricity. Power is captured from the gravitational force of water falling through penstocks to water turbines connected to generators. The amount of power available is a combination of height and flow. A wide range of Dams may be built to raise the water level, and create a lake for storing water.

Salinity gradient energy is called pressure-retarded osmosis. In this method, seawater is pumped into a pressure chamber that is at a pressure lower than the difference between the pressures of saline water and fresh water. Freshwater is also pumped into the pressure chamber through a membrane, which increases both the volume and pressure of the chamber. As the pressure differences are compensated, a turbine is spun creating energy.

The production process is different at power plants of different constructions and of different kinds. In atomic power plants, for example, it is not so simple as in hydroelectric plants.

Text D

New words and word combinations:

1) energy conservation – энергосбережение; 2) protection – защита;     3) improvement – улучшение; 4) nuclear power – ядерная энергетика;           5) nuclear weapons – ядерное оружие; 6) massive spending – массовые расходы; 7) proliferation – распространение; 8) complementary – дополнительный; 9) to evolve – развивать; 10) consumption – потребление; 11) depletion – истощение; 12) maintenance – техническое обслуживание; 13) unavoidable – неизбежный; 14) proliferation – быстрое разрастание; 15) controversial – спорный; 16) disposal – уничтожение.