We explain what geothermal energy is, how it is classified, its advantages and disadvantages. Also, what are its characteristics and uses.
What is geothermal energy?
It is known as geothermal energy. a type of renewable energy obtained from the use of the planet's interior heat. This heat is transmitted to the surface through the rocks, minerals and magma found inside the Earth.
The Earth's core is made of iron and nickel. It is located about 5000 km deep, and its temperature can exceed 6700 °C. This heat is transmitted to the surface and can be recovered by geothermal technology and used to provide heat or electricity to the population.
Geothermal energy is a renewable and relatively clean energy source. Renewable because it comes from the heat of the Earth's core, which is an inexhaustible source of energy. And relatively clean because it does not produce greenhouse gases or other pollutants. However, pollution and environmental deterioration can occur when drilling and installing geothermal fields.
The word “geothermal” comes from the union of two Greek words: geoswhich translates as “earth” and thermos which means “heat”. It translates as “the heat of the Earth.”
Geothermal deposits
Geothermal energy is extracted from deposits located beneath the Earth's crust. It is hot water and steam which, buried under layers of rock, are at very high temperatures.
The hot water and steam extraction process consists of drilling until reaching the deposit and removing the boiling substance. On the other hand, Water is injected again so that it is heated again and in this way geothermal production is renewed and can be used sustainably over time.
There are also dry depositswhich are underground areas of high temperature but without the presence of water. These deposits can be used to create a thermal circuit from the injection of water and its subsequent recovery. This process is known as “geothermal stimulation,” and it serves to take advantage of the accumulated heat even though there is naturally no more water or steam in the deposit.
Distribution of geothermal energy in the world
Geothermal deposits are found throughout the world, but their geographical distribution is not uniform. Most of the deposits are located in regions with high tectonic and volcanic activity such as:
- The Pacific basin. This region is known as the “Pacific Ring of Fire” due to its high seismic and volcanic activity. Countries such as the United States, Mexico, Guatemala, El Salvador, Nicaragua, Costa Rica, Panama, Chile, Japan, the Philippines, Indonesia and New Zealand have important geothermal deposits.
- Europe. Iceland, Italy, France, Portugal and Greece are the countries on this continent that have the most geothermal deposits.
- Africa. Kenya, Ethiopia and Tanzania are the African countries that have the largest number of geothermal deposits.
In these places the heat from the Earth's interior is closer to the surface due to geological and volcanic activity and is easier to extract.
Types of geothermal energy
Depending on the water temperatures, geothermal deposits can obtain three types of energy:
- High temperature geothermal energy. It is above 150 °C. It is used for large scale power generation.
- Medium temperature geothermal energy. It is between 90 °C and 150 °C. It allows exploitation on a more limited basis, such as in small power plants and factories.
- Low temperature geothermal energy. It is below 90°C. It is used for heating buildings and for industrial processes that do not require much energy.
Advantages of geothermal energy
The advantages of geothermal energy can be grouped into economic and ecological:
- From the economic point of view. Geothermal energy has a low operating cost since it does not need fuel to operate. At the same time, the deposits usually have a long useful life, so the initial investment is amortized over time in the very long term.
- From the ecological point of view. Geothermal energy emits low levels of greenhouse gases, does not produce large volumes of polluting waste and constitutes a source of renewable and sustainable energy over time.
Disadvantages of geothermal energy
The main disadvantage of this type of energy is the geographical limitation. Geothermal energy extraction is only viable in those places where geothermal activity is significant.
On the other hand, although after the deposits are installed the extraction cost is low in relation to other energy sources, The initial investment required to start taking advantage of geothermal energy is usually very high.
Finally, the construction of this type of energy deposits can produce pollution and significant modifications to the local ecosystems.
Uses of geothermal energy
The main uses of geothermal energy are:
- Heating and cooling. Geothermal energy can be used for heating and cooling buildings by installing geothermal heat pumps. These pumps extract heat from the Earth in winter and use it to heat buildings, and in summer they extract heat from the building and transfer it to the Earth.
- Electricity generation. Geothermal plants use steam or hot water extracted from the ground to drive turbines and generate electrical energy.
- Industrial processes. Geothermal energy can be used for industrial processes that require a lot of heat, such as pasteurizing food, sterilizing objects, and cooking and drying products.
- Desalination. Geothermal energy is also used to produce desalinated water through evaporation and condensation processes. Thanks to geothermal energy, sea water is heated and evaporated, and then condensed to produce fresh water.
Geothermal plants
The world's first geothermal plant was built in Larderello, Italy, in 1904. Since then, geothermal plants have expanded throughout the world. According to 2020 data from World Geothermal Energy Council, It is estimated that around 14.9 GW of geothermal energy is used worldwide.
The United States is the largest producer, with more than 80 geothermal plants and a power generation of 3.7 GW. Indonesia with more than 47 plants and 2.1 GW of production is the second most important, and the Philippines with more than 20 plants and 1.9 GW of energy production is the third most important in the world.
Other countries such as Mexico and Türkiye also have many geothermal power plants, but their production levels are lower than those mentioned above.
Future of geothermal energy
Geothermal energy has great potential as a renewable energy source and is expected to continue to grow in importance in the future. It is estimated that geothermal energy could generate up to 10% of the world's electricity by 2050.
Some of the factors driving the growth of geothermal energy are:
- There is greater awareness of the need to reduce greenhouse gas emissions and combat climate change.
- Geothermal energy exploration and production technology has advanced, and this allows access to deeper and more distant geothermal resources.
- Demand for electrical energy increased worldwide, especially in developing countries with high geothermal activity, such as Indonesia and the Philippines.
- The long-term production costs of this energy are stable, which makes it an attractive energy source for investors.
In addition to electricity production, geothermal energy is also expected to have a greater impact on direct applications such as heating and cooling of buildings and industrial and agricultural processes.
References
- Endesa (2021). Geothermal energy: discover what it is and how it works. Endesa
- Catalan Energy Institute (sf). Types of geothermal energy. Icaen
- UN (sf). What are renewable energies? Action for the climateto. A
- Tarbuck, E., & Lutgens, F (1999). Earth Sciences. An introduction to physical geology. Prentice Hall.
