Why geothermal constitutes less than 1% of global energy production

2024 could by the year of geothermak, according to a MIT studies

by Lorenzo Ciotti
Why geothermal constitutes less than 1% of global energy production
© Jeff J Mitchell / Staff Getty Images

Geothermal energy is one of the most interesting renewables as, at least on a theoretical level, it could power entire cities, allowing an almost constant influx of clean energy over time. And MIT studies say 2024 could be the year of geothermal, already considered one of the most innovative systems ever. It currently constitutes less than 1% of global energy production.

It is an energy that is always present and exploitable, regardless of both the short and long-term weather conditions of the place where it is exploited and does not present the daily and seasonal cyclical phenomena typical of solar energy.

Geothermal energy
Geothermal energy© Jeff J Mitchell / Staff Getty Images

Geothermal energy is based on the exploitation of the natural heat of planet Earth, due to the thermal energy released by the natural nuclear decay processes of radioactive elements such as uranium, thorium and potassium, naturally contained in the rocks present within the Earth.

The heat generated by these processes causes the temperature to increase with depth, starting from the earth's surface towards the center of the earth, according to a geothermal gradient that varies depending on the types of rocks in place and the geological structures present. This energy can be used both as a source of electricity production and directly as a heat source, according to the cogeneration process.

Geothermal constitutes less than 1% of global energy production

Currently, almost all of the geothermal systems exploited at an industrial level are conventional systems. The hydrothermal systems that represent them are made up of porous and permeable rock formations in which rainwater and rivers infiltrate and are heated by high-temperature rocks due to the presence of a heat source of magmatic origin at depth.

The temperatures reached vary from 50-60 °C up to a few hundred degrees. This type of circuit constitutes the most widespread and used source of geothermal energy.

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The extraction of geothermal energy involves high sustainability in medium-short times, if exploited rationally with correct planning of the injection of exhausted fluid; the sustainability of production over longer times is more critical, especially for steam-dominant systems for which there is generally not a complete restoration of initial production even with injection.

The re-injection of fluids is however fundamental to ensure the sustainability of production, but correct planning of the number, arrangement and depth of the injector wells, as well as the pressure and flow rate of the injected fluid, is required to avoid excessive cooling of the reservoir rocks and the generation of induced earthquakes.

Furthermore, in the geothermal industry the release of gas and solid particulates is generally lower than the emissions produced by conventional energy sources, and therefore there is less pollution of the surrounding environment.

The construction and maintenance of the structures of a geothermal project can imply effects with environmental impact, which must be monitored and minimized.