How Geothermal Energy Works

The Earth’s interior is organized in different layers with a core that is like an incandescent mass that radiates from the interior of the Earth to the exterior and, as we go deeper into it, the temperature will increase by 2 to 4ºC for every 100 meters. In this way, the water in the depths of the Earth’s core is at a very high temperature and pressure, as this water comes out towards the earth’s surface, it will experience a progressive change of state to water vapor and will come out at great pressure. , in the form of a jet or as a hot spring .

It is possible to take advantage of these water sources to produce energy, this is geothermal energy . Logically, it does not have the energy potential of solar energy, but it can be industrially exploited to produce energy as heating, for greenhouses or for aquaculture.

In order to access this source of hot water from the subsoil, it is necessary to drill holes on the surface . These holes are usually between 10 and 15 centimeters in diameter and their depth depends on various factors, such as the dimensions of the space to be heated or the geological conditions of the terrain to be drilled.

Inside these holes, we have geothermal probes (like a system of pipes made of polyethylene, normally) completely sealed and filled with circulating water or antifreeze liquid. It is in this pipe system where the heat exchange between both systems takes place .

It is a closed system, in such a way that when the liquid descends to depth, it heats up and rises again to operate a pump and that is where it gives up its heat to the refrigerant and the medium used for heating. This heat exchange takes place at a depth of between 50 and 100 meters. The more water the layer of soil contains under the hole, the greater the heat exchange. It is for this reason, that the water table is perforated (the water it contains is not used, but its temperature).

There are also horizontal pipe systems, instead of vertical ones. However, these systems are less efficient, since they require a large surface area and being shallow, they do not obtain as much energy and it is more subject to fluctuations.

The geothermal energy sources include:

• Hot water reservoirs : use hot water sources or underground aquifers. They were already known in times of the Roman Empire, when baths or thermal baths were built from these.
• Dry reservoirs : uses the energy of dry hot rocks of the Earth’s interior that are created as a result of the release of internal magma. Two wells are drilled and the water is introduced through one, which when it contacts the interior with these rocks, exits at great pressure and temperature through the second well. An example can be found in the Timanfaya National Park.
• Geysers : the hot water comes out through terrestrial orifices in the form of steam columns and jets. They are not as common, but they are abundant in especially volcanic areas such as Yellowstone National Park and parts of Iceland.

The exploitations of this type of energy began in Larderello (Italy) in 1904 and since then it has been present in a large number of countries , mainly volcanic , such as:

• Iceland.
• New Zealand.
• Japan.
• Philippines
• The western United States.

Currently, the world’s largest power in geothermal energy is Iceland , because it is an eminently volcanic country, where 99% of homes use this type of energy, many of which are ecological and self-sufficient . In the United States, one power is the state of California, which supplies up to 90% of the country’s geothermal energy.

Geothermal energy in Spain

In Spain, geothermal energy is important in greenhouses and spas in Ourense or Murcia. Also, it is said that Galicia may be one of the first communities to use this energy as a means of heating or air conditioning.

If you want to read more articles similar to How Geothermal Energy Works , we recommend that you enter our Renewable Energy category .