Geothermal energy: a major renewable energy resource

Geothermal energy-which covers all forms of heat extracted from the earth-has been used on a commercial scale for over 100 years, The resource is available in one form or another in every country and can provide base-load electricity and heat on a continuous and sustained basis. More than 70 countries now exploit geothermal resources, the global scale of which means they do not suffer depletion in the same way as more finite mineral resources. This paper reviews the various forms of geothermal energy production currently in operation and planned around the world. It concludes that geothermal energy has potential for further substantial growth and can make a large contribution to reduction of greenhouse gas emissions, particularly in developing countries.