Geothermal Energy: A Review
Chijindu Ikechukwu Igwe
Abstract
Geothermal energy is energy created by the heat of the Earth. To extract energy from the underground, water is most times used as the heat carrier. As the crust is highly fractured and thus permeable to fluids, surface water, in most cases rainwater, penetrates at depth and exchanges heat with the rocks. Two main forms of heat transfer occur within the crust: conduction and convection. Where rocks are much fractured and circulating fluids are abundant, the resulting convective heat transfer is very efficient and can be easily exploited by drilling wells and discharge the hot fluids to the surface. The Earth's geothermal resources are theoretically more than adequate to supply humanity's energy needs, but only a very small fraction may be profitably exploited. Drilling and exploration for deep resources is very expensive. Forecasts for the future of geothermal power depend on assumptions about technology, energy prices, subsidies, plate boundary movement and interest rates. Geothermal energy is a well-established and relatively mature form of commercial renewable energy characterized by a high load factor, which means that its installed capacity produces significantly more electricity during a year than other sources like wind and solar power plants. Geothermal power plants provide stable production output, unaffected by weather or climate, resulting in high capacity factors ranging from 60% to 90% which is ideal for making the technology suitable for base load electricity production.