Green power is an important addition to any energy portfolio, and geothermal electricity is an attractive alternative renewable sources such as wind and solar.
Energy is brought to the surface by extracting hot water that is circulating amongst the sub surface rocks, or by pumping cold water into the hot rocks and returning the heated water to the surface, to drive steam turbines to produce electricity.
Alternatively geothermal energy can be used directly for heating and cooling; in industry and agriculture, and domestically.
Many countries have examples of the right conditions that could lead to geothermal power development.
Geothermal projects today centre around the exploitation of hydrothermal resources.
Hydrothermal developments have tended to cling to areas of hight tectonic activity, where hot-water reservoirs area abundant. It is no coincidence that the countries with the largest installed geothermal capacity (the US, Philippines, Indonesia, Japan, New Zealand) all lies on the pacific ring of fire.
Just as oil seeps used to mark the spot, volcanoes, geysers and hot springs are good indicators of hydrothermal potential. Unfortunately, however, volcanoes and geysers are not usually where large population centers and thus electricity markets tends to be located.