Research States Geothermal Energy As An Alternative With Little Environmental Impact
Geothermal energy, a method of capturing heat from the interior of the Earth’s crust, is still underutilized worldwide. So far, its application is almost entirely restricted to heating homes and thermal baths. Already consolidated in Europe and the United States – the current largest producer –, the places that most use this type of energy here in Brazil are Poços de Caldas (MG) and Caldas Novas (GO), thermal water parks.
Its history goes back to the 15th and 16th centuries, when the capacity of the soil was already used to cool the air inside the houses and guarantee a little better ventilation. It is clear, then, that geothermal is not a new thing. In recent years, there has been a growth in the impact of this type of energy production technology, which is captured from the deepest layers of the soil.
“Here in Brazil, as we don’t have layers with very high temperatures, it ends up being used more recreationally”, says Professor Alberto Hernandez Neto, from the Department of Mechanical Engineering at USP’s Polytechnic School. However, the country has the possibility of using this type of energy for the cooling and air conditioning of buildings, by rejecting heat from the environment into the ground. Unlike northern countries, which use it for heating, here it is used for cooling.
The professor explains that the soil has a stable temperature all year round, which allows it to reject more heat at a lower temperature, increasing efficiency and consuming less energy. Today, some air conditioners use cooling towers, which use a lot of water. Geothermal, on the other hand, does the same job without this expense.
different technologies
To heat and cool by means of geothermal energy, different technologies have to be used. In the first scenario, it is necessary to remove heat from the earth to heat the water, which turns into steam and passes through a turbine. This movement generates mechanical energy, which a generator will later transform into electrical energy.
As for cooling, an air-conditioning system removes heat from the environment, which is rejected to the ground by a system of ducts. Here, the soil serves as a heat sink. Studies so that part of the heat that is rejected is used to preheat so that, when heating completely, there is less energy expenditure, are already in progress. Alberto Hernandez says this technology would be applied in hotels and hospitals.
Geothermal energy can even be generated from the heat exchange between the walls of subways and the ground. This is already applied in Europe, where this energy is even used to heat homes.
national situation
Brazil is known for its diversified and, in a way, green energy matrix. Solar energy is already the second largest energy source in the country , behind hydraulic energy and ahead of wind energy. Geothermal, by contrast, has not advanced, but interest is growing. “Interest is growing. There is great potential in Brazil for this type of system to start being used, because today we are very concerned with the issue of reducing the environmental impact of buildings”, explains the professor.
Geothermal can be an interesting alternative with little environmental impact. Note, however, that the soils are different in Brazil, as well as the demands for air conditioning. Hernandez considers that this is not an insurmountable obstacle and that it would be possible to implement a considerable energy generation from the internal heat of the earth.
But what are the best systems to apply in Brazil? “Energy is not just the solution. The idea we have for energy production is that it be done with more than one source”, he says. Diversification of sources is extremely important to guarantee energy generation even in times of crisis. “This composition of sources is what will provide the security and stability of energy production in the country”, he adds.
For the implementation of a plant, geological conditions such as volcanoes, geysers, hot springs or meeting places of tectonic plates are ideal. As water and steam are found in Brazilian soil, at low or moderate temperatures, the construction of a geothermal power plant is more complicated, however, not impossible. There are forms of unconventional power plants, such as the Enhanced Geothermal System (EGS).
“Brazil has all the potential to maintain itself with a clean and sustainable matrix”, reiterates Hernandez. In addition to geothermal energy, energy generated using green hydrogen, an option still under study and in the process of being more widely used, is also a possibility.