What is geothermal energy
Geothermal energy is a type of energy that uses heat stored inside the Earth’s crust. It is a renewable and unquantifiable energy. The expression geothermal comes from the Greek term geowhich means ‘land’, and thermoswhich means ‘heat’.
In other words, geothermal energy is energy that takes advantage of the thermal energy stored inside the Earth in the form of hot water, water vapor and hot dry rock.
Some examples of geothermal energy available in the environment are: volcanoes, geysers and hot springs.
exist direct and indirect uses of geothermal energy. Direct use takes advantage of the immediate heat of the subsoil, always less than 150º C. It covers the production of domestic hot water (use in autoclaves and disinfection) and air conditioning. Indirect use refers to obtaining electricity, only possible in deposits with more than 150º C.
How does geothermal energy work?
Geothermal power plant in Iceland.
To understand how geothermal energy works, it is necessary to understand how it is produced in nature and how it is obtained for consumption.
How is geothermal energy produced in nature?
The sun’s radiation stops affecting the subsoil at a certain depth. From that point on, the soil temperature rises as this depth increases. That is, the closer it gets to the earth’s magma, the hotter the subsoil will be.
In places with volcanic activity or with great movement of tectonic plates, the heat of the Earth’s magma is more superficial. In these places, areas of molten rock or hot dry rock abound. The heat from the magma raises the temperature of the subsurface water and produces steam.
This process generates three types of reservoirs or geothermal deposits: sources, aquifers and dry deposits.
Thermal sources: They are formed when water or steam rises to the surface and produces phenomena such as geysers and so-called hot springs or waters.
Hot water aquifers: They are the hot water deposits that remain in the Earth’s crust.
dry deposits: They are formed by hot dry rocks and other molten materials.
How is geothermal energy obtained for consumption?
Direct geothermal energy can be obtained through facilities called heat pumpswhich contain a heat exchanger.
These pumps take advantage of the heat of the immediate earth’s crust, and thus power the infrastructure directly (houses, buildings or industries). Direct use is also possible by laying exchanger pipes.
Indirect geothermal energy is obtained in geothermal plants or power plants, which are responsible for transforming it into electrical energy. These plants must be close to the large deposits.
Geothermal plants have two production wells. One is responsible for obtaining hot water and steam, and the other is responsible for reinjecting the water into the subsoil, which allows the cycle to be renewed.
In the case of dry reservoirs, water is injected through a borehole into the hot dry rock. Upon coming into contact with this material, the water raises its temperature and generates steam. Then the water is recovered.
The energy produced spins a turbine at thousands of revolutions per minute. This turbine starts a generator that transforms mechanical energy into electrical energy. The resulting electrical energy is channeled to a transformer, responsible for distributing it for consumption.
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Types of geothermal energy
Geothermal energy is classified based on temperature. The two essential types are: low or very low temperature geothermal energy and medium or high temperature geothermal energy.
Low temperature geothermal energy
This type of energy takes advantage of the subsoil temperature, which reaches up to 150º C. This temperature does not depend on the season of the year, which is why it is constant. Low temperature geothermal energy is the most common as it is intended for direct consumption.
High temperature geothermal energy
It is one that takes advantage of tectonic activity, capable of achieving temperatures above 150º C. It is only possible in those places on the planet where important tectonic phenomena occur, such as volcanoes or geysers. High temperature geothermal energy is used to obtain electrical energy.
Advantages of geothermal energy
It does not depend on the climate like wind or solar energy, since it is obtained from the natural temperature difference between the surface and the interior of the earth. Therefore, its availability is constant. The economic investment is recovered quickly, that is, between 4 and 8 years. It allows savings of up to 50% in energy consumption compared to other energy sources. It requires little investment in operation and maintenance. No It generates noise pollution since it does not use compressors or fans. The extraction takes up little space and does not require ventilation. Production wells do not use fuel. Consequently, they do not generate smoke or CO2.
Disadvantages of geothermal energy
In general terms, geothermal energy can generate emissions of hydrogen sulfide, which is not always detectable, as well as other potentially toxic substances. The exploitation of geothermal energy involves the intervention of the landscape in order to drill into the Earth’s crust.
Uses and applications of geothermal energy
Geothermal energy has a large number of applications in daily and industrial life. With the exception of obtaining electricity, the vast majority of uses of geothermal energy qualify as direct.
Below we present some examples.
Heating water for domestic and industrial use; space heating; cooling by geothermal cold pump and absorption; swimming and spas; bleaching, cooking and pasteurization; greenhouses; drying of agricultural and industrial products (such as food and wood); heating and soil sterilization; aquaculture; dry cleaning; ice manufacturing and conservation; desalination; obtaining electrical energy (indirect use).
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