Geothermal energy is an energy source more or less renewable , volcanic type, which involves the use of internal heat margins planet Earth.
Since the recorded temperature increases as we approach the Earth’s core, there are many groundwater layers under the surface in which the water is heated and subsequently emerges as large jets of steam and hot liquid, thus giving rise to geysers and waters. hot springs that have been used by humanity since ancient times for various purposes. They are very frequent, in addition, in areas of high volcanic activity.
There are, then, three types of geothermal deposits, namely :
- Hot water. They can form a source or be underground (in aquifers). They are usually exploited through a double well system, which allows the reinjection of water so as not to deplete the reservoir.
- Dry. These are boiling deposits with gas but without water, which can be used and then renewed by injecting the liquid to start them up again.
- Geysers Thermal deposits at such pressure that periodically they emit steam and boiling water to the surface as a drain.
Although this energy is supposed to be renewable , since the heat of the earth does not run out, it has occurred in various exploitation sites that magma cools and ceases its water heating, in addition to being accompanied by small but frequent earthquakes . That is why it is said that geothermal energy is not entirely renewable .
Geothermal energy can be used for electricity generation, refrigeration and direct use of heat.
Examples of geothermal energy
- Volcanoes . Perhaps the most extreme and dramatic manifestation of geothermal energy is volcanoes, responsible for much environmental and biological destruction during their eruptions, which throw boiling magma (lava), toxic gases and ash in suspension to the environment. Its energy potential is gigantic but wild, so they are not really usable in any way, but rather a natural disaster that many human populations must deal with periodically.
- Geysers . This is the name of a set of geoelectric plants located 116 km from the city of San Francisco, United States, considered the largest complex of its kind in the world. It is capable of producing more than 950 MW of electricity at 63% of its productive capacity, using in 21 different plants the steam emanating from more than 350 active geysers.
- Desalination plants . Geothermal energy is currently used in the desalination of water, through the use of its heat for a cycle of evaporation and condensation of the liquid, which allows the removal of salts and other heavy elements present, for example, in seawater. This is an economic and ecological process put into vogue since 1995 by the American Douglas Firestone.
- Geothermal heat pumps. For both cooling and heating, geothermal energy is usable through air conditioning pump systems, to maintain the temperature of entire buildings. It is a caloric source of high performance and low electrical demand, which takes advantage of the constant temperature of the first layers of the earth’s surface to reduce compressor cycles.
- Timanfaya Oven-Grill . Taking advantage of the volcanic activity of the Canary Islands, the restaurant “El Diablo” of local artisanal food designed an oven that operates based on the exposure of food to heat from the magmatic and geothermal activity of Timanfaya National Park on the island of Lanzarote . This ” vulkan grill ” consists of a series of grilles installed in a well that goes directly into the earth.
- The geothermal power station of Hellisheiði. Located in Iceland, near the Hengill volcano, 11 kilometers from the capital, this plant generates electricity and thermal energy, of 303 MWe and 133 MWt respectively. It is a growing installation since its inception in 2006, in the hands of the company Orkuveita Reykjavíkur.
- Greenhouses geothermally heated . In the city of Valencia, Spain, as well as in other similar projects in Chile, heat energy from the underground thermal waters is already being used, through water extraction and injection cycles to maintain the heat of a stable greenhouse all year round. Despite the seasons. This could maximize production with minimal energy cost and decrease pitch CO 2 that often accompany these emissions subsoil and are air pollutants.
- Cerro Prieto geothermal power plant . The world’s second geothermal plant, with a capacity of 720 MW and expansion plans that would lead it to reach even higher figures, is located very close to the homonymous volcano in Mexicali, Baja California, Mexico. It consists of five individual units located to take advantage of the heat emanating from the magmatic activity of the subsoil.
- Agricultural drying . Taking advantage of the heat of geothermal energy to transmit it to agricultural substances that require drying, such as milk pasteurization or food sterilization, is a project of special interest to the Food and Agriculture Organization of the United Nations. In April 2015, this type of site was formally proposed, especially useful for developing countries, as it is a constant and economic source of energy.
- Yellowstone Park geysers. More than half of the world’s 1000 geysers are in this American National Park, considered the oldest in the world. This area has a strong and continuous volcanic activity, which is why it is covered with lava flows and sediments, with more than 200 geysers and 1000 different thermal sources.