What is geothermal energy?

We explain what geothermal energy is, and how it is obtained. Its advantages and disadvantages. Examples of geothermal energy.

1. What is geothermal energy?

Geothermal energy is a type of more or less renewable energy, of volcanic origin , that is, it consists of harnessing the internal heat of the Earth to extract from the subsoil water at high temperatures, from which caloric energy can be extracted or that can Used to generate electricity.

As we get closer to the planet’s core, temperatures rise considerably, as there is more pressure , more gravity , and less distance from the molten metal core that is the heart of the Earth. That is why numerous deposits of boiling water can be found underground, which can be released and driven to the surface, giving rise to large steam jets, geysers and hot springs that, since ancient times, have been used by humanity for various purposes . These types of deposits are very frequent in areas of high volcanic activity.

This type of energy is popular because it comes from a renewable source, although there are complications that can lead to the extinction of the deposits. These, incidentally, can be of three types:

• Dry . Hot steam and gas deposits , devoid of water in a liquid state .
• Hot water . They can be sources or underground aquifer deposits, whose waters are compressed at high temperatures.
• Geysers . Thermal deposits whose pressure is so high, that they should spoil steam or boiling water sporadically to the surface in large jets.

2. How is geothermal energy obtained?

As stated, geothermal energy comes from the waters of the earth’s subsoil, whose pressure and temperature occurs naturally. In these deposits, geothermal plants that release water or steam are usually installed, use it to generate electricity or to extract heat and redirect it , and then re-inject water at ordinary temperature to the well, to continue the cycle.

There are also more homemade ways of obtaining, such as heating by geothermal pumps, which allows the use of gas or boiling water from the subsoil to provide heat to entire homes or buildings, if not to heat greenhouses and agricultural drying facilities.

3. Advantages of geothermal energy

The main advantages of this type of energy are:

• It is natural . It comes from the planet itself, so it does not involve a technological or biological risk to consider.
• It is economical . It does not require constant raw material, nor does it depend on an international market of inputs that suddenly increases its usefulness.
• It is ecological . It does not throw large wastes into the environment , nor does it generate annoying noise, and the emission of CO ₂ and other greenhouse gases that accompanies it is lower than that generated by other forms of obtaining energy , such as the burning of fossil fuels. On the other hand, take advantage of modest extensions, without the need to dam rivers or cut down forests.
• It is reliable . In terms of the human scale, it is basically an inexhaustible source of energy.

4. Disadvantages of geothermal energy

At the same time, geothermal energy has the following setbacks:

• Deterioration of the landscape . The installation of the plants usually has a cost in terms of landscape , which impacts some measure on tourism .
• Indirect pollution . The water extracted from the subsoil can be accompanied by polluting substances that, when evaporated, must be disposed of in some way and can be toxic.
• It requires specific conditions . It cannot be done anywhere, but in volcanic areas (except for the geothermal air conditioning pump).
• Earthquake risk . Sometimes, water reinjected into the well can cool the magma, producing microsisms and exterminating the site forever.

5. What is geothermal energy used for?

This type of energy is directly usable, to heat buildings, dry agricultural or industrial inputs , even cook food. It is an immediate heat source.

In geoelectric plants, on the other hand, this heat is used to boil water (or the steam directly extracted from the well is used) to mobilize a complex of turbines that, as in nuclear electrical installations or fossil fuels, generate electricity usable

6. Examples of geothermal energy

Some examples of this type of energy are:

• The Geysers , a set of geoelectric power plants 116 km from the city of San Francisco in the United States, considered the largest complex of its kind in the world. It can produce over 950 MW of electricity being at 63% of its productive capacity, taking advantage of the steam emanating from more than 350 active geysers.
• The Timanfaya Oven-Grill , in the Canary Islands, takes advantage of the magmatic activity of the region for the “El Diablo” restaurant of artisanal food, on the island of Lanzarote. This oven takes advantage of a well that goes directly into the subsoil.
• The volcanoes , the best known and devastating natural manifestation of geothermal energy, consist of explosions underground matter that shed boiling magma (lava), toxic gases and fly ash to the environment. They have a gigantic but unapproachable energy potential.