What is Geothermal Energy?

120327_GeothermalEnergyThe centre of the Earth is around 6000 degrees Celsius – easily hot enough to melt rock. Even a few kilometres down, the temperature can be over 250 degrees Celsius if the Earth’s crust is thin. In general, the temperature rises one degree Celsius for every 30 – 50 metres you go down, but this does vary depending on location.In volcanic areas, molten rock can be very close to the surface. Sometimes we can use that heat.Geothermal energy has been used for thousands of years in some countries for cooking and heating.The name “geothermal” comes from two Greek words: “geo” means “Earth” and “thermal” means “heat”.
Hot rocks underground heat water to produce steam.
We drill holes down to the hot region, steam comes up, is purified and used to drive turbines, which drive electricgeo generators.
There may be natural “groundwater” in the hot rocks anyway, or we may need to drill more holes and pump water down to them.
The first geothermal power station was built at Landrello, in Italy, and the second was at Wairekei in New Zealand. Others are in Iceland, Japan, the Philippines and the United States.
In Iceland, geothermal heat is used to heat houses as well as for generating electricity.
If the rocks aren’t hot enough to produce steam we can sometimes still use the energy – the Civic Centre in Southampton, England, is partly heated this way as part of a district heating scheme with thousands of customers