Hydro-Electricity
Hydro comes from a Greek word meaning water. Hydro-electricity uses the potential energy of water stored in lakes. The potential energy in the water is turned into kinetic energy when it flows down through the pipes and into the power station. Gravity causes the downward movement of the water. Water under pressure enters the power station and is directed onto the turbine. The kinetic energy of the moving water is turned into mechanical energy as it makes the turbine spin around. The turbine is connected via a shaft to the magnets which in turn spin around inside the coils of conductor. Here the mechanical energy is turned into electrical energy ready for distribution and use.
The amount of energy available from a hydro-electric power station depends on two major factors:
The water pressure acting on the turbine
This depends on the height through which the water has to fall to get to the turbine. The greater the height (or head) of the water above the turbine the greater its pressure. Higher water pressures provide more energy for transfer to the turbine. Water falling through 100 metres, for example, can produce twice as much power as the same volume falling only 50 metres.The volume of water available.
The greater the quantity of water available, the greater the number and/or size of the turbines that can be spun and the greater the power output of the generators. The amount of power is directly related to the quantity of water - twice the volume produces twice the amount of power.
An aerial view of the
Catagunya Dam and
Power Station
Dams are constructed to provide water storages for hydro-electric power stations. The stored water can be used when needed and the higher water levels provide extra head (or pressure).
What is a watt?
A watt (W) is a term used to measure the rate at which work can be done by electricity. A 60 watt light globe uses 60 watts of electricity. A typical pop-up toaster uses 1200 watts. One thousand watts is called a kilowatt (kW) and one million watts is called a megawatt (MW).
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