Geothermal energy is energy from the heat of the earth. It has been used for thousands of years in some countries for hot water, cooking and heating. It can also generate electricity using steam produced from heat found beneath the surface of the earth. It is not common in Australia, but is used in some parts of New Zealand and through Europe.
When water flows over hot rocks, hot water and steam are created and escape to the earth's surface. Bubbling mud pools, hot springs and geysers are examples of geothermal energy. Volcanoes are very violent examples of this type of energy.
The hot water and steam created underground can be used to create electricity (by turning turbines) to heat homes and other buildings. The steam is collected, and used to power a generator, in the same way it is used in a coal fired power station.
The Maoris of New Zealand use hot rocks to cook food in the ground. Around the world people also swim in warm natural springs to help soothe body aches and pains.
Another form of geothermal energy is called "hot rock". This is where water is pumped below the surface to areas of hot rock. The water then turns to steam, and is pumped back to the surface to drive a turbo-generator.
Australia does not currently produce electricity from geothermal energy. However, tests are being carried out on a "hot rock" power station.
Advantages of using geothermal energy
- It's free once built.
- It is renewable (ie. it won't run out).
- It does not take up very much land, and does not spoil the landscape.
Disadvantages of using geothermal energy
- Some geothermal sites may 'run out of steam'.
- Hazardous minerals - which are difficult to dispose of - may be produced.
- Geothermal energy sites can be difficult to find.