Geothermal energy is one of the oldest and yet least exploited renewable energy sources compared to others like solar or wind power. Despite being a technology known for decades, its use has gained greater importance in recent years due to the increased demand for sustainable and clean energy sources.
Geothermal energy uses the Earth's internal heat to generate electricity or provide heating. By drilling into the Earth's surface in areas with high thermal activity, deeper layers can be accessed where the temperature is high enough to heat water. This process releases steam that is used to move turbines connected to electricity generators, or directly to heat urban and rural infrastructure. The extraction of this heat is mainly carried out in specific locations, characterized by the presence of geological factors such as volcanoes or tectonic faults, which makes the distribution of geothermal plants uneven across the planet.
The process of extracting geothermal energy
Harnessing geothermal energy is a technical process that requires drilling into the earth in locations where the underground temperature is high enough to utilize thermal resources. This type of energy is found at depths ranging from 3.000 to 10.000 meters below the Earth's surface. At these depths, groundwater is heated by hot rocks, reaching temperatures that can exceed 300°C in some cases.
The process begins with drilling wells to extract water and steam from the Earth's interior. This steam is channeled to power one or more turbines connected to electric generators. After use, the water and steam can be reinjected underground to begin the cycle again, making this a closed-loop system that minimizes the massive extraction of underground resources.
Types of geothermal resources
There are several types of geothermal resources that can be used to produce energy:
- Dry geothermal systems: These consist of areas where underground rock formations do not contain water, but have sufficiently high temperatures. These systems require the injection of water into the rocks to produce steam.
- Dry steam reservoirsIn this type of system, steam is trapped in underground cavities. This steam can be extracted directly to drive the turbines.
- Hot water reservoirs: These are the most common. In these reservoirs, the groundwater is at a high temperature and, once extracted, it turns into steam when depressurized.
- Enhanced Geothermal Systems (EGS): Here, rock formations are modified by fracturing them (similar to hydraulic fracturing in the gas industry), allowing water to circulate through the cracks and heat up, generating steam.
In terms of technology, there are several ways to convert geothermal heat into electricity:
- Dry steam plants: They directly use geothermal steam to move the turbines.
- Flash steam plants: High-pressure hot water is decompressed and transformed into steam, which then moves the turbines.
- Binary cycle plants: A secondary fluid with a lower boiling point than water is used, allowing energy to be generated in formations with lower temperatures.
Advantages of using geothermal energy
Geothermal energy has multiple benefits that make it an attractive alternative to other renewable energy sources:
- An renewable resource, since the amount of thermal energy available inside the Earth is practically unlimited on a human scale.
- It is capable of generating energy constantly 24 hours of the day, unlike solar or wind energy, which depend on weather conditions and time of day.
- Geothermal energy has a low carbon footprint, which contributes to the mitigation of climate change. There is no combustion or significant greenhouse gas emissions.
- Geothermal plants take up little space compared to solar or hydroelectric plants.
Furthermore, international studies highlight that geothermal energy can be a key solution for many developing countries with significant geothermal potential. Regions such as Africa, Asia , and parts of South America have vast geothermal resources that could help reduce their dependence on fossil fuels and improve access to electricity.
New trend: geothermal energy on a global level
Geothermal energy has gained particular importance in countries like the United States and Indonesia , which are world leaders in both installed capacity and new projects. The United States, for its part, reached an installed capacity of more than 3.900 MW in 2023, while Indonesia has expanded its capacity to 2.418 MW, with significant investment earmarked for further expansion in the coming years.
Other countries such as Turkey, the Philippines , and Mexico have also made progress in this area. Turkey, for example, surpassed 1.600 MW of installed capacity in 2023 and, although its growth is slower, it remains one of the leading countries in Europe.
Challenges and disadvantages
Despite its many advantages, the use of geothermal energy is not without its challenges. The first limitation is that geothermal resources are only found in specific geographic areas, such as those with volcanic activity and tectonic faults, in quantities that can be used for energy production. As a result, its implementation at a global level is limited.
Furthermore, the high initial exploration and drilling costs are a critical factor. Drilling to great depths is an extremely expensive process, and the exploration phase carries risks, as success in extracting efficient resources is not always guaranteed.
Another drawback is that, although electricity generation may be constant once the plant is in operation, its capacity to be used depends greatly on the geological conditions at the site. Variations in the availability of thermal resources can mean fluctuations in the efficiency of the plants.
It should also be noted that, in some cases, improper use of the facilities can lead to underground degradation, which could cause damage to aquifers or even trigger minor earthquakes known as induced earthquakes.
Therefore, there are still economic and technical barriers that must be overcome for geothermal energy to expand globally. However, these limitations are being addressed through technological advances and the implementation of risk mitigation systems.
With ongoing projects and continued advancement in new drilling and generation technologies, geothermal energy continues to position itself as one of the most sustainable and strategically viable solutions for the future of global energy.