6)POWER STATIONS THAT USE RENEWABLE ENERGY SOURCES

HYDROELECTRIC POWER STATION
Hydroelectric power station use the energy of falling water to produce electricity. When water accumulates in a reservoid behind a high dam, it has a lot of potential energy which becomes kinetic energy when the water falls down to a lower level. This kinetic energy moves the blades of a turbines, which are usually located at the foot of the dam. The turbines are connected to the rotors of generators, which generate electricity. There are two main types of hydroelectric power station:
-In a conventional hydroelectric stations, the water flows from the reservoir to the turbines through a high-pressure conduit. Then it flows out, usually into a river.


-In a pumped-storage hydroelectric power station, the water flows from the turbines to a second reservoir. Then it is pumped back up to the higher reservoid and stored for later. These stations are often built in areas where there isn't enough rain or river water to keep the upper reservoir full, so the water must be reused.

SOLAR POWER STATIONS
Solar power stations use energy from sunlight to generate electricity. There are two main types of solar power station:Solar thermal and photovoltaic.
Solar thermal stations
Solar thermal sations can use sunlight in two ways:
-With solar collectors that absorb sunlight in order to produce heat.
-With mirrors called heliostats that reflect and concentrate sunlight in one place.

Photovoltaic stations
In photovoltaic stations, solar panel convert sunlight directly into electricity. Each panels contains many photovoltaic cells.
Small solar power installations can provide energy for homes and rural areas. Excess power can be stored in batteries or accumulators and used at night.