Geothermal energy is produced from the heat naturally contained in the subsoil of our planet, generated by the molten nucleus of the Earth. The deeper you dig, the higher the temperatures reached. We usually find three types of geothermal energy:
- Shallow geothermal energy (up to 1.5 km) at very low temperatures (less than 50 C);
- Deep geothermal energy (up to 2 km) at medium or high energy (reaching temperatures up to 150 C), which allows the production of electricity;
- Very deep geothermal energy (5 to 10 km) at a very high temperature (up to 300 C).
The benefits of geothermal energy are numerous. It is renewable, local, uninterrupted and independent of weather conditions. In addition, its production emits no CO2 and has a low environmental footprint. Geothermal energy can also provide a long-term solution to transitioning from a fossil fuel economy without contributing to climate change.
The most productive sites to generate electricity from geothermal are often located in volcanic environments, as they provide a large amount of thermal energy.
The principle of a geothermal power facility is to extract the heat contained in the ground, either to use it in the form of heating (heat network) or to transform it into electricity. If the plant is able to produce both, it is called cogeneration.
In high and very high energy systems, the steam rises with enough pressure to turn a turbine, in order to produce electricity.
In medium energy systems, the production of electricity requires a technology using an intermediate fluid that is circulated in the boreholes, which is heated with geothermal water. This fluid is charged with thermal energy, boils and vaporizes; spinning a turbine that produces the electricity.