Geothermal energy is one of the many naturally occurring energy sources like solar energy, wind energy etc that are being developed for a greener present and future. It literally means Earth’s heat energy, with Geo standing for Earth and thermal meaning heat (thermal energy determines the temperature of any matter, in this case it is that of the Earth).
Most humans are now aware that the Earth’s core is very very hot and fluid, which results in the formation of volcanoes which spit hot magma on to its surface. These very volcanoes, along with the process of radioactive decay of minerals and Earth’s formative process, are the reason for the presence of the internal thermal energy. This very high temperature at the core is distributed to the surface by the process of thermal conduction through many rocks that make up the area between the core and the surface. The difference between the temperature at the center and the surface of the Earth, called the geothermal gradient, is the major driving force for this conduction to take place.
Old, exhausted, coal mines modified to generate geothermal energy for hot and cold water supply: Parts of the Netherlands, which were coal mines before being shut down due to environmental concerns, are being re-proposed to capitalize for renewable geothermal energy. The old, shut down mines had remained flooded with water for more than 30 years. Heat pumps go down into these flooded water shafts and extract heat from these mine shafts supplying the district heat systems which in turn supply hot and cold water to more than 350 homes and businesses in the town of Heerlen. The temperature of the water changes with depth and therefore a shallow heat pump can provide cool water whereas a deeper pump at the same site brings hot water to the surface. The project is dubbed as the Minewater project.
Tapping heat from groundwater to heat airports and other areas of high energy consumption: Paris’ Orly airport, one of the two major airports serving the city, is all set to go green in 2011, by extracting heat from groundwater around the airport. The idea is to draw water upwards by natural pressure at a temperature of 74 degree Celsius and pump it into the airports heating system. The used water will be pumped back into the water table at about 45 degree Celsius in order to prevent damage to the regional water table.
Geothermal power plants turning heat energy to electricity: Among the many countries in the front-run for developing sustainable alternatives to petroleum based energy, the island nation St Lucia is conducting a unique exercise to meet its power requirements through naturally abundant geothermal energy, reducing its dependence on Mexico. The plant uses the steam from geothermal sources to power turbines or generators. The installed capacity at the geothermal plants is 120 mw, enough to support the needs of the Caribbean countryâs 175,000 inhabitants.
Near zero environmental impact is the foremost benefit of geothermal energy. It causes no pollution, has no greenhouse effect and does not require any fuel to run it. In simple terms it is cost effective, sustainable, reliable and environmentally friendly.
In theory, the Earth’s geothermal resource is more than enough to meet all human power needs, but in practice and with current technology, it is possible to only exploit a small portion of this resource due to the kind of rocks that lie above and below such resources. There is also a chance of the plant running out of steam often for decades, or harmful gases and minerals finding their way up to the Earth’s surface.
The fact that making use of geothermal energy can deplete the natural fluids at a 10 percent higher rate than is natural, is a huge worry for environmentalists. This can lead to permanent and irreversible damage to the geysers and can even cause land to sink in vast geographical regions. The process of using geothermal energy, is pollution free but there are certain concerns of mineral poisoning of rivers and lakes if the geothermal fluids containing elevated levels of arsenic, mercury and other minerals, are released in the waterways. Poisoning by Hydrogen Sulphide is also a major concern for workers and people directly dependent on geothermal energy.