What is geothermal energy? The term geothermal comes from the Greek geo meaning earth and therine meaning heat. Geothermal energy is therefore energy derived from the natural heat of the earth. Heat flowing from the Earth's hot interior due to movements of crustal plates, areas of high heat flux, can be localized near the surface where convective circulation plays an important role in bringing heat closer to the surface (World Bank Group, 2012). The Earth's crust, on which we live and depend, is largely the product of millions of once-active volcanoes and enormous volumes of magma that did not erupt but instead cooled beneath the surface. Such persistent and widespread volcanism has given rise to many valuable natural resources across the world. ...Groundwater heated by large, still-hot magma bodies can be harnessed for geothermal energy. -- Extracted from: Brantley, 2014, Volcanoes of the United States, USGS General Interest Publication. Deep circulation of groundwater along fracture zones will bring heat to shallower levels, collecting heat flow from a large area and concentrating it in shallow reservoirs or discharging it as hot form. springs. These tanks can contain hot water and/or a stream. By drilling into these reservoirs, hot water and/or steam is delivered to the surface where it is used for direct-use applications, or high-pressure steam is separated to drive turbines for power generation. Low-energy wastewater from such power generation is then typically reinjected into the reservoir, or used further for direct heat applications. This technology allows it to be used to produce electricity and provide domestic and industrial heat. Geothermal energy has been proven to be reliable, economical, environmentally friendly and renewable (World Bank Group, 2012). In general, there are two main categories, (1) high temperature resources and (2) moderate/low temperature resources. High temperature geothermal resources – 220 degrees Celsius and above – are found mainly in volcanic regions and island chains. Moderate to low temperature resources are found on all continents. High temperatures are almost always used for electricity generation, while most low-temperature resources are used for direct heating purposes or for agriculture and aquaculture. How does the exploitation of geothermal energy work? Deep wells, a mile or more deep, can tap reservoirs of steam or water. very hot water that can be used to drive turbines that power electricity generators. There are 3 types of geothermal power plants used today, and they are: