Hydroelectricity

Hydroelectricity is electricity that is made by the movement of water. It is usually made with dams that block a river to make a reservoir, or collect water that is pumped there. When the water is "let go" the huge pressure behind the dam forces the water down shafts that lead to a turbine, this causes the turbine to turn, which turns a generator which makes electricity. It is a form of renewable energy and reduces pollution.

The energy of falling water has been used by humans for thousands of years.

Advantages of hydroelectricity

The way the electricity is produced does not harm the environment as much as fossil fuels like oil or coal. Hydroelectricity is very powerful, safe and produces no waste. Hydroelectricity can be made very quickly. This makes it useful for times when demand for electricity is high. Water that has been stored in a dam can be "let go" when needed, so the energy needed can be made quickly. Also hydroelectricity can not run out as long as there is a good water supply. Once the dam is built the electricity is free, no waste or pollution produced and electricity can be generated constantly.

Disadvantages of hydroelectricity

The building of large dams to hold the water can damage the environment. In 1983 Australian government stopped the Tasmanian state government from building a dam on the Gordon River in Tasmania after a huge public protest. The dam would have flooded the beautiful Franklin River. The Three Gorges Dam in China will be the world's largest hydroelectricity project. The dam has flooded a huge area, meaning that 1.2 million people have had to be moved. Scientists are concerned about many problems with the dam, such as pollution, silt, and the danger of the dam wall breaking.

Other websites

• The Climate Change Guide easy-to-understand information on hydroelectricity