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Geothermal energy is seen as one of the alternatives to using fossil fuels to generate electricity

Payal Mehta image by Pixabay

Geothermal energy is a type of renewable energy obtained from heat coming from the Earth's interior. The process of harnessing this energy is done through large holes in the ground, since our planet's heat is located below the Earth's surface. Of Greek origin, the word "geothermic" is formed by the terms geo, which means Earth, and therme, which corresponds to the temperature.

This energy source can be used directly (without requiring the production of energy in power plants, using only the heat generated by the ground) or indirectly (when the heat is sent to an industry that transforms it into electrical energy). Geothermal energy can be used to heat water in residential areas or even entire cities during the winter. It can also be used for heat production and for use in heaters or thermal appliances in greenhouses, fishing grounds or recreational areas.

In Brazil, geothermal energy is used only in leisure areas. Two cities that use their thermal sources for tourism are Poços de Caldas (MG) and Caldas Novas (GO). These locations rely on the emergence of water heated by the geothermal process. In addition to the high temperatures, these waters have large amounts of minerals that are good for the skin and the whole body, such as potassium, selenium, calcium, zinc, chlorides and magnesium.

Earth Structure

The Earth is covered by the Earth's crust, a thin layer of rock that is found above the mantle, a layer with great depth and basically composed of magma. The result of a melting process, this material is a mixture of rocks in a liquid or pasty state, dissolved gases and crystals.

All this internal heat manifests itself in some areas of the surface, usually in volcanic eruptions, geological crevices or areas of internal heating, causing the emergence of steam geysers and hot springs.

Geothermal Plants

Geothermal power plants transform geothermal energy obtained from heat coming from the Earth's interior into electricity, and are installed near areas where there is a large amount of steam and hot water. In this way, geothermal reservoirs provide the energy needed to power turbine generators, producing electricity. The first Geothermal Plant was built in Italy in 1904.

How is geothermal energy produced?

Geothermal plants are responsible for converting the Earth's internal heat into electrical energy. The first step in this process is the capture of hot water or steam inside the Earth through specifically designed tubes. This steam is then directed to the plants, where it is released under strong pressure. When released, the steam moves turbines that rotate mechanically. Finally, the turbines drive the generator that produces electrical energy.

In some electrical energy production systems using the Earth's heat, water is injected into the heated subsoil so that it turns into heat and returns in the form of steam, which, as in the previous case, activates the turbines that activate the generator .

Advanced drilling methods are under development, with the aim of increasing the exploitation of this electrical source and reducing the costs arising from the loss of machinery. If that is possible, geothermal sources could compete in global energy markets, currently controlled by the use of fossil fuels.

Geothermal energy in Brazil and worldwide

The three countries with the largest production of geothermal energy in the world are the United States, the Philippines and Indonesia. In addition to them, other countries have opted for the production of geothermal energy, such as China, Japan, Chile, Mexico, France, Germany, Switzerland, Hungary and Iceland.

Currently, around 25 countries on the planet use geothermal energy, and in Brazil there is no great potential for exploring this type of energy, as it is explored in transition areas between the tectonic plates. Also, there is not much incentive to use it. This is due to the fact that the country has a robust energy matrix established on water bases, in addition to using other energy sources such as natural gas.

Advantages of geothermal energy

The main advantages of geothermal energy are:

• It does not operate by burning fuels. Thus, there is no need to import and purchase raw materials, reducing production costs. Less is spent on geothermal power plants than on oil or nuclear power plants, which have a high cost of acquiring primary products;
• Does not emit polluting gases. This means that it does not contribute to the intensification of the greenhouse effect, unlike fossil fuels;
• Does not harm the soil. Despite internal perforations, geothermal energy does not erode the soil, flood large areas or contaminate groundwater, as with other energy sources;
• It is not vulnerable to the weather. Climatic variations do not interfere with the operation of geothermal power plants, unlike what happens with solar or wind energy, for example.
• Benefit for outlying areas. In areas where there is not ample access to the electricity grid, geothermal power plants can meet the needs of the population, especially in regions suitable for their installation;
• It has a flexible production. Electricity production at these plants may vary according to demand, not depending on water reservoirs or availability of raw materials, among others.

Disadvantages of geothermal energy

The main disadvantages are:

• Possible sinking of the land. Although they do not wear out the ground, geothermal power plants can wear out the inner areas of the crust, which can cause shocks to the surface. Therefore, in some cases, it is necessary to inject water or another component to fill the internal compositions;
• Noise pollution and high local heating. Generally, geothermal power plants make a lot of noise, a fact that, added to the high local heating, makes it impossible to install them close to homes and communities;
• Emission of H2S (hydrogen sulphide). Along with water vapor, it is common to have the release of sulfur dioxide, which may not attack the atmosphere, but is harmful to human health, in addition to being highly corrosive and having an unpleasant odor;
• It only operates in a few places. As with most energy sources, geothermal can only be operated in favorable areas, with high internal heating and where access to thermal areas is easy and less expensive. This makes its use in most places unfeasible;
• Possible contamination of rivers and lakes. Thermal fluids can release mineral compositions that, if not properly retained, can affect watercourses in areas close to power plants;
• High investment cost. Although the maintenance of geothermal plants is small, their construction and installation are expensive due to the technology used in the process, a factor that may change in the coming years.

Despite being a renewable energy source that does not emit greenhouse gases, geothermal energy still has relevant disadvantages. Large-scale exposure to hydrogen sulphide, for example, can cause a variety of damage to a worker's health.

Irritations in the eyes, nose or throat are some of the initial symptoms. Problems can also affect the respiratory system, causing memory loss, headaches and even impaired motor function. In addition, experts say that symptoms such as heart failure, kidney failure, vomiting, itching and redness of the skin may appear, not to mention possible irreversible sequelae, such as psychological disorders.