Geothermal energy takes heat from the Earth. It provides continuous, 24-hour a day, clean, sustainable energy. It is considered a renewable resource because the heat emanating from the interior of the Earth is essentially limitless. The heat continuously flowing from the Earth’s interior, which travels primarily by conduction, is estimated to be equivalent to 42 million megawatts (MW) of power, and is expected to remain so for billions of years to come, ensuring an inexhaustible supply of energy.
According to the International Geothermal Association, Geothermal energy has become established as a reliable and environmentally benign source of power. Installed capacity in 2010 is the equivalent of 10-15 typical nuclear power plants, with almost no atmospheric emissions or hazardous wastes. Proven high availability and load factors, and no dependence on sunlight or weather, makes geothermal energy a key resource in a sustainable energy future.
The growth of geothermal utilization for power generation has averaged roughly 5.5% per year over the last 30 years, and the geothermal installed capacity in the world has been increased by about 1000 MWe every 5 years. The installed capacity will be 10,715 MW at the end of year 2010.