Most of our energy comes from the sun but there is also an enormous reservoir of energy in the form heat beneath the Earth. Sometimes this heat rises to the surface in the form of hot water or steam. In a few places, powerful jets of steam shoot up from the ground as geysers. Geothermal steam and hot springs have been used for more than a hundred years to generate electricity.
Geothermal power plant in New Zealand
How It Works
Either, steam is used directly to drive a turbine, or the hot water is used to evaporate another liquid with a lower boiling point, and the vapour from the second liquid drives the turbine.
Hot Dry Rocks
Everywhere in the world, rocks deep below the surface are very hot. In some places, these hot rocks are closer to the surface than elsewhere. One such place is central Australia.
It is possible to make electricity using the heat in these rocks by pumping water down to them and capturing the seam that is produced when the water is heated by the rocks. The hot rock formations in central Australia contain sufficient potential energy to supply all of Australia’s power needs for hundreds of years.
Since no fuel is needed to generate geothermal power, it has practically no environmental impact.