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Geothermal energy: definition, advantages and disadvantages

Today it may seem difficult for us to imagine our life without electricity or other basic comforts. However, the current situation on our planet is forcing us to seek new resources and sources of energy, as the fossil fuels we use are beginning to be in danger and threatening to run out. From AgroCorrn we are going to talk to you about geothermal resources as a renewable energy source in this article on geothermal energy: definition, advantages and disadvantages .

You may also be interested in: Biomass energy: advantages and disadvantages
  1. What is geothermal energy – definition
  2. Types of geothermal energy
  3. Geothermal energy sources
  4. Advantages of geothermal energy
  5. Disadvantages of geothermal energy

What is geothermal energy – definition

The geothermal energy (from the Greek geo, earth, and thermos , heat, ie, “heat of the Earth”) is a type of renewable energy , as we deduce from its name, used as a source internal heat of the Earth stored below the surface. The Earth’s core is made up of a solid incandescent sphere and is mainly made up of an alloy of iron and nickel that radiates heat outwards. Thus, the deeper layers have higher temperatures and in them the heating of water masses can take place that, when rising in liquid or vapor state, are manifested in the form of geysers or thermal springs.

This heat is not transmitted in a linear way by all points of the planet and, furthermore, it depends on the material it passes through. The most superficial area of ​​the earth’s crust, the lithosphere, transports heat by conduction (by contact between the two bodies but without the transfer of matter) and as the depth increases, the heat is transmitted by convection ( produced by the transfer of heat-carrying matter, generally a gas or liquid, to the receiving body).

Currently, geothermal energy is used for obtaining heat, cooling and generating electrical energy .

Types of geothermal energy

There are 4 types of geothermal energy depending on the temperature of the water when it is expelled:

  • High temperature geothermal energy , between 150 and 400º. On the earth’s surface it becomes steam and generates electricity through a turbine.
  • Geothermal energy of medium temperature , between 70 and 150º, exploited by small power plants.
  • Low temperature geothermal energy , between 50 and 70º, used mainly for domestic needs such as heating and, more specifically, in greenhouses or agriculture.
  • Very low temperature geothermal energy , between 20 and 50º. As it is not enough for air conditioning, geothermal heat pumps must be used for both heating and cooling.

Within this section we can also refer to geothermal energy from hot rock reservoirs, about 5-8 kilometers deep under the ground (dry reservoirs).

Geothermal energy sources

Generally, the rate at which these deposits are exploited is usually high, so areas that would take hundreds of years to recover should not be saturated.

The geothermal sites , sites where large concentrations of geothermal energy accumulate, can be classified into three types:

Hot water reservoirs

This type of reservoir can occur in the form of sources or underground in aquifers. These first have been used for a long time as thermal baths by the Romans. Underground reservoirs have high temperatures but at low or medium depths, so that hot water or steam can flow naturally. However, if you want to extract it for exploitation, you must make two or an even number of wells through which to extract the water and reintroduce it once cooled to prevent the aquifer from drying out and being lost as a thermal reservoir.

Dry fields

These fields do not need water to produce energy, since in reality it is a type of artificial production. They are found underground at a not very high depth, and are formed by dry rocks at high temperatures due to exposure to interior magma. Cold water is injected into them, which when in contact with the hot rock produces water vapor, which comes out under pressure through a second hole also in contact with the hot rock bed.


They may be the clearest example that we all have in mind, but that is not why they are excessively abundant, most of them being distributed between Iceland and Yellowstone National Park (USA), mainly volcanic areas .

These geysers are large sources of boiling thermal water capable of violently expelling columns of steam and hot water. The explanation for this phenomenon is based on the contact of groundwater with rocks that are kept at high temperatures inside the Earth. This causes the water to heat up and volatilize almost instantaneously, rising to the surface at high speed and expelled as if the geyser were a siphon of water and steam.

Advantages of geothermal energy

This type of energy has both advantages and disadvantages that should be known. Thus, among the main advantages of geothermal energy we highlight the following:

  • It is a renewable resource, provided that its extraction rate is lower than the natural rate of recharge.
  • It is considered a “clean” energy, as it reduces the consumption of fossil fuels and other non-renewable resources.
  • It hardly produces waste, which greatly reduces the environmental impact.
  • The greenhouse effect CO2 emission is much lower than that produced by combustion to obtain the same energy, so it hardly contributes to global warming.
  • It represents a saving since its costs for the production of electricity are low.
  • Provides a wealth of resources; It is believed that today it can provide more energy than all fossil fuels (oil, natural gas, coal and uranium) combined.

Disadvantages of geothermal energy

In addition, as we have discussed before, geothermal energy also has drawbacks :

  • Low development as it is an energy that is beginning to be used. In Spain it is hardly used and the extraction methods can currently be considered somewhat ordinary.
  • Leaks can occur in which hydrogen sulfide is expelled (in high doses it is lethal to man), arsenic, ammonia or other substances that can cause contamination of the land and nearby waters.
  • The plants or geothermal plants must be installed in places where the heat of the subsoil is high.
  • This energy is not transportable and must be used on-site , that is, in the same place where it is produced (local supply).
  • They produce an impact on the landscape, since the construction of the facilities to extract the heat from the underground rocks and the magma must be carried out on the terrain.
  • Small earthquakes occur in areas close to geothermal plants due to sudden cooling and the breaking of the rocks of the earth’s crust.
  • Thermal pollution.
  • Noise pollution. In initial phases in which it is necessary to drill wells, up to 115 decibels are reached (almost the noise generated by an airplane engine), although once carried out, its normal operation produces hardly any outside noise (it is among the 75 and 80 decibels, the noise of a vacuum cleaner).

If you want to read more articles similar to Geothermal Energy: definition, advantages and disadvantages , we recommend that you enter our Renewable Energy category .

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