Geothermal energy: building from sustainability

Lately, there is a lot of talk about renewable energies to reduce the environmental impact that the industrial revolution, throughout its stages of innovation, has been generating on the planet almost without us realizing its consequences.

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Among the new technologies that have emerged in the light of renewable and sustainable energies is geothermal energy, a resource that takes advantage of the ignition of the center of the Earth to generate electricity. The objective of this article is to address the topic of geothermal energy from a business perspective, emphasizing its main applications and advantages.

What is geothermal?

Geothermal is the branch of science that deals with the study of the heat existing inside the Earth and the extraction of geothermal energy, one of the most efficient renewable energies but also less used to date.

Geothermal energy uses the natural heat generated by the Earth's core, preserved and transferred through incandescent rocks that came into contact with the material at very high temperatures and gave rise to geothermal energy. Despite the obvious advantages of its application, there are still not many places in the world where it is implemented, and in other regions, it is practically unknown.

Northern Europe is where this technology that takes advantage of the Earth's heat has been most developed, and to a lesser extent, Japan and the United States have also been using this sustainable resource for several years.

Although one of the main uses and objectives of geothermal energy is to generate electricity, the truth is that the heat given off by the center of the Earth is not hot enough as would be expected. The maximum temperatures recorded there do not exceed 100°C, a curious feature considering that there are places on the Earth's surface that reach very high temperatures that exceed 50°C.

For this reason, the main efficient application of geothermal energy is thermal energy for industrial use and also for domestic use. Now, when the extraction of heat admits lower temperatures below 25°, it means that it is being extracted at a very shallow depth, so the application of the geothermal energy obtained will be used to heat water and air-conditioned spaces.

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How is geothermal energy produced with the heat obtained from the depths of the Earth?

High temperatures of over 4000°C cause some of the rock in the center of the Earth to melt and form hot molten rocks called magma. These heats also help the mantle behave plastically and parts of it convect upward since it is lighter than the surrounding rock.

Rock and water in the Earth's crust can reach temperatures of around 370°C. The thermal energy contained in rocks and fluids can be found from shallow depths to several miles below the Earth's surface.

To obtain the necessary geothermal energy, wells up to a mile deep or more are drilled into underground reservoirs to harness geothermal resources. These resources can be exploited from natural heat, the permeability of rocks and water, or through enhanced geothermal systems, which enhance or create geothermal resources through a process called hydraulic stimulation. These geothermal resources, whether natural or enhanced, drive turbines linked to electricity generators.

The first recorded instance of geothermal heat used to produce electricity was in Larderello, Italy, in 1904. However, geothermal heat has been used for bathing since the Paleolithic Age. Monkeys in Japan have also been shown to use hot water from hot springs to keep warm during the winter months in mountainous regions.

We can identify different geothermal energy subtraction techniques to be used later.

1. Buried horizontal collection: this system works at a shallow depth and houses a gear of polyethylene pipes or horizontal collectors, which contain water with antifreeze inside.
2. Vertical collection from geothermal probes: this collection system is recommended when there is not enough space to carry out the previous technique. Here the pipes are placed vertically until reaching maximum depths of 150 meters.
3. Catchment by rivers or lakes: use thermal waters to introduce catchments and make a temperature contrast.

After the geothermal energy has been subtracted, the next step is to transform the heat into energy. For this purpose, a geothermal heat pump is used and it is combined with refrigerant energy, so that it becomes a gaseous state, and accesses the condenser and compressor where new heat exchange is carried out for heating and hot water applications.

Advantages of applying geothermal energy

As a renewable energy source, the main advantages of geothermal energy are environmental. It produces only one-sixth of the carbon dioxide emitted by a clean natural gas power plant. Geothermal energy is also cheaper than conventional energy, with savings of up to 80% compared to fossil fuels.

Unlike other renewable energy sources, such as solar and wind, it is constantly available.

However, despite being cheap, sustainable, and environmentally friendly, geothermal energy also has its drawbacks.

First, production is limited to areas near tectonic plate boundaries. Also, some places can get cold after decades of use. Although cheaper than fossil fuels once a plant has been built, drilling and exploration at these sites are expensive.

This is due in part to the amount of wear and tear drills and other tools experienced in such harsh environments. Geothermal plants can release hydrogen sulfide, a gas that smells like rotten eggs. Finally, some geothermal fluids contain low levels of toxic materials that must be disposed of.

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In short, geothermal energy is a technology applied to a little exploited natural resource such as the terrestrial heat present in the center of the Earth, which generates geothermal energy capable of providing heating and energy of sustainable origin to people. In this way, we understand that Jules Verne's imagination in creating an adventure to the center of the Earth today exceeds mere science fiction, like so many other futuristic alternatives of the same style.