Renewable energies are undoubtedly the future in the medium and long term. Fossil fuel reserves are nearing depletion, and the world must shift towards alternative and sustainable energy sources. In this transition to a cleaner energy model, geothermal energy is gaining traction. Despite its importance and potential, many people are unaware of the diverse uses of geothermal energy and its scope as a viable option.
In this article, we will take an in-depth look at the main uses of geothermal energy, its essential characteristics and its relevance in the context of the energy transition.
Features and operation
Geothermal energy is a renewable source that uses the internal heat of the Earth. This heat is generated mainly in the Earth's core due to the disintegration of radioactive elements such as uranium, thorium and potassium. When these elements decompose, they emit heat that rises from the deepest layers towards the Earth's crust.
As we descend deeper into the Earth, the temperature increases. Generally, the temperature rises between 2 and 4 °C for every 100 meters of depth , meaning that at greater depths we find more intense heat sources. This thermal gradient allows groundwater in certain areas to heat up and turn into steam, forming high-temperature aquifers, or generating geysers or hot springs.
Geothermal energy production depends on the temperature of the geothermal resource. In high-temperature reservoirs, the heat can exceed 150 degrees Celsius, allowing for the generation of electricity using turbines. In other cases, such as low-enthalpy geothermal energy , the heat is primarily used for heating and domestic hot water, without generating electricity.
Types of geothermal energy according to temperature
Depending on the temperature of the resource, we can classify geothermal energy into four main types, each applicable to different energy needs:
1. Very low temperature (less than 30ºC)
Primarily used for heating and hot water production in homes and buildings, the most common system in this temperature range is the geothermal heat pump . This system exchanges heat with the ground to provide heating in winter and cooling in summer. It is a highly energy-efficient option with a long lifespan and low maintenance.
2. Low temperature (30ºC to 100ºC)
This type of resource is used in urban heating networks, spas, drying of agricultural products, fish farms and other medium-scale industrial applications.
3. Medium temperature (100ºC to 150ºC)
Suitable for generating electricity using binary cycle technologies, where a fluid with a boiling point lower than water is evaporated, turning turbines to produce electricity. It is also used in industrial processes that require a constant supply of thermal energy.
4. High temperature (more than 150ºC)
In these systems, steam generated in underground aquifers is used directly to drive steam turbines that generate electricity. This is the most common type of geothermal energy when it comes to commercial electricity production. It is found in geothermally active areas, such as those near tectonic plates and volcanic zones.
Uses of geothermal energy
One of the main advantages of geothermal energy is its versatility. It can be used both to generate electricity and to provide heat in various sectors:
- Electricity generation: In areas with high-temperature deposits, such as areas near volcanoes or geological faults, natural steam is used to drive turbines and generate electricity. Plants such as binary cycle or dry steam plants are examples of high-efficiency facilities that take advantage of this resource.
- Heating and air conditioning: In homes and buildings, geothermal energy is used to provide heating using heat pumps. Heat from underground is extracted through buried pipes and transferred to the interior of buildings. This system is especially efficient in cold climates, where maintaining a constant temperature underground is crucial.
- Industrial and agricultural applications: In the agricultural sector, it is used for drying products, heating greenhouses and fish farms, and in other industrial processes such as salt extraction or equipment sterilization. Its use guarantees a more sustainable production process with a lower environmental impact.
Advantages and disadvantages of geothermal energy
Geothermal energy has multiple advantages that make it one of the most promising renewable energies, but it also presents certain challenges that must be considered:
Advantages
- Renewable and practically inexhaustible: The Earth's internal heat is continuously available, and unlike other renewable sources, it is not dependent on meteorological factors.
- Low environmental impact: Geothermal plants emit significantly lower levels of CO2 than conventional power plants, and can operate with a level of independence from fossil fuels.
- Long-term economic savings: Although the initial installation cost is high, once installed, geothermal energy is much cheaper to operate than other forms of energy.
- Extended shelf life: Geothermal installations typically have a lifespan of more than 50 years, justifying the initial investment.
Drawbacks
- High initial investment: The costs of drilling and developing geothermal infrastructure are high, especially in areas where underground heat is at great depth.
- Local environmental impacts: Heat extraction can generate small emissions of gases such as hydrogen sulfide, and in some cases, drilling work can generate minor local earthquakes.
- Geographic specificity: Not all areas of the world are suitable for the installation of geothermal plants, limiting their expansion.
Domestic geothermal energy applications
In the home, geothermal energy is primarily used through geothermal heat pumps , which allow for efficient heating and cooling of spaces and hot water production. There are three types of installations for capturing underground heat:
- Vertical geothermal system: This is a system in which the probes are inserted vertically into the ground, reaching depths of up to 150 metres. It is the most efficient in terms of energy use, although it requires a greater investment.
- Horizontal geothermal system: The pipes are laid horizontally at a depth of 1 to 2 meters. Its cost is lower than the vertical system, but it requires more space on the surface.
- Groundwater collection system: In this case, underground aquifers are used, extracting the water to use its heat and then returning it. This system is very efficient, but its viability depends on the availability of adequate water resources.
Using these systems not only reduces the electricity bill of users, but also contributes to reducing the carbon footprint and maintaining a more sustainable home. Geothermal energy is undoubtedly a long-lasting and environmentally friendly solution for domestic heating and cooling needs, with the added advantage of being compatible with other renewable sources such as solar energy.
Geothermal energy is set to become one of the main players in the energy transition. Although the initial installation cost can be high, the investment is recovered over the years due to the low operating cost and the constant dissipation of underground heat.
With proper planning and the right choice of system, both industries and domestic users can benefit from an inexhaustible source of energy that respects the environment.