GEOTHERMAL ENERGY

Geothermal energy is a natural, clean, and renewable source of power that utilizes heat from the Earth's subsurface to produce steam, generate electricity, or provide heating for water and indoor spaces.

What is geothermal energy? The Earth is constantly active. As you go deeper into its crust, the temperature steadily rises by an average of 30°C per kilometer. This heat comes from the natural decay of radioactive elements within the planet. Geothermal technology enables us to tap into this thermal gradient, which is one of the few energy sources that doesn’t depend on the Sun.

How geothermal energy works

As you dig deeper into the ground, the temperature increases by roughly 3°C for every 100 meters. In certain areas, this rise in temperature is even more pronounced due to specific geological features, like volcanic activity or tectonic shifts. In these naturally hotter regions, geothermal technology can harness the heat at shallower depths.

How is steam generated underground?

In permeable rock formations, rainwater or underground rivers come into direct contact with hot rocks. In some areas with particularly favorable conditions, temperatures can exceed 50-100°C (ecoage.it). This heat transfer naturally generates steam, which rises to the surface.

When this steam reaches the surface, it is directed into turbines to produce electricity. Alternatively, the heat can be channeled through a network of pipes to provide heating for homes, offices, factories, or even greenhouses and thermal baths.

Note: In many geothermal plants, cold water is often injected back underground to boost steam production. When this water comes into contact with the hot rock, it turns into steam, providing a consistent flow to keep turbines running smoothly. This ensures a steady production of heat and electricity without interruptions.

Where geothermal energy is used

Geothermal energy is utilized in many countries around the world, especially in regions with higher underground thermal gradients. Iceland, for example, is a country with significant volcanic activity and benefits from a large temperature difference between its geothermal sources and the cold surface climate. Geothermal technology is widely used there to generate electricity.

Geothermal energy is also harnessed in other countries on a smaller scale, in areas where underground thermal activity is particularly high. Italy, for instance, built its first geothermal plants in Tuscany.

The Larderello geothermal power plant: Italy is home to the world’s first geothermal power generator, built in 1904 in Larderello, Tuscany, by Piero Ginori Pozzi to capture steam from underground. The Larderello plant is still operational today.

The largest geothermal power plant in the world is in California, with a capacity of 1,400 MW (ecoage.it). Other large geothermal plants have been built in Africa.

Geothermal power plants

Geothermal technology has been applied to build large, medium, and small-scale plants, depending on the potential of the underground heat sources.

Mini geothermal systems

In addition to large geothermal plants, small-scale or micro-geothermal systems have been developed over time. These systems are designed to meet the energy needs of a single building or a few homes. They utilize the underground temperature gradient to provide heating or cooling for apartments. One example of mini geothermal systems is geothermal heat pumps. According to ecoage, this is a promising and growing sector of eco-architecture, though installation costs are still high.

Advantages and disadvantages of geothermal energy

The main advantages of geothermal energy include:

• Renewable energy: It is a renewable energy source that doesn’t deplete with use, as it’s drawn from the Earth’s natural heat.

  Note: Unlike other renewable sources, geothermal energy is not intermittent.

• Clean energy: Geothermal energy produces no pollution or greenhouse gas emissions. Its impact on the environment and ecosystems is minimal, making it a clean energy source.

The main disadvantages of geothermal energy include:

• Limited geographical potential: Geothermal energy can only be utilized in areas where geothermal reservoirs are close to the surface. It’s not feasible in locations where the heat is deeper underground. Currently, geothermal energy meets about 1% of the world’s energy needs (ecoage.it), making it a useful but limited alternative source.
• Unpleasant odors: Geothermal plants release hydrogen sulfide, which gives off the unpleasant smell of rotten eggs, typical of thermal areas.
• Impact on the landscape: Geothermal plants are industrial structures characterized by networks of pipes and clouds of steam, which can detract from the visual appeal of the surrounding landscape. However, according to ecoage, this impact can be mitigated through eco-friendly design in industrial plant architecture.