Geothermal Energy: Energy from the heart of the Earth

A History of Heat and Energy

Geothermal energy, used since prehistoric times, has proven to be a reliable and sustainable energy source. Throughout various periods and civilizations, humans have utilized the Earth's internal heat for diverse purposes, from ancient Roman thermal baths to modern electricity generation. The industrial exploitation of geothermal energy began with the construction of the first commercial geothermal plant in Larderello, Italy, in 1913. This energy source is now considered crucial for the transition to renewable sources.

What is geothermal energy?

Since the beginning of time, the Earth's internal heat manifested as steam, has been used for various purposes, such as heating, cooking, and hot springs. The 19th century saw the development of the first industrial methods for harnessing geothermal energy. By the early 20th century, electricity generation from this source was successful.

Geothermal energy is a renewable energy source that uses the Earth's internal heat to produce electricity. Geothermal plants require high temperatures, ranging between 150°C and 370°C, obtained from hydrothermal resources like steam and hot water. Because geothermal plants do not depend on climatic variations, they can continuously generate energy, with a capacity factor ranging from 60% to 90%. According to the IRENA 2023 report, geothermal energy contributes 181 MW of green energy to the total renewable energy capacity.

Cerro Pabellón Geothermal Plant: Innovation and Sustainability in Chile

Pioneers of geothermal energy in South America

Cerro Pabellón, located in the Atacama Desert, is the first and one of the most innovative geothermal plants in South America. It is 4,500 meters above sea level, making it the highest-altitude geothermal plant in the world.

This plant uses cutting-edge technology to extract heat from the ground and convert it into electricity, providing a constant and renewable energy source. Cerro Pabellón has an installed capacity of 83.81 MW, avoiding the emission of more than 150,000 tons of CO2 annually.

How is geothermal energy transformed?

In order to start generating geothermal energy, it's essential to tap into the Earth's heat. This is achieved by extracting a combination of steam and water from a geothermal reservoir using an extraction shaft or underground well, which can extend to depths of up to 3,000 meters.

This allows natural vapors to rise to the surface and be directed to the plant.

The mixture then goes to a cyclonic separator where steam separates from water molecules. The liquid water is pumped through heat exchangers (preheater) before being reinjected into the subsurface to reheat. At the same time, the extracted steam goes to vaporizers—both Preheater and Vaporize exchange energy with the working fluid, which operates in a closed circuit. The working fluid is a retrograde isopentane fluid with a low boiling point (T_eb=28°C @ 1 bar), and it generates isopentane vapor that spins a turbine to create mechanical energy. The energy is then transferred to an alternator, where it is converted into electricity.

The electricity is sent to substations that distribute it through the grid.

After this process, the geothermal steam, having transferred energy to the working fluid (isopentane) in the vaporizer, cools down and turns back into water. This water is then reinjected, along with the geothermal liquid, into the subsurface through the reinjection system (comprising pumping units) and reinjection wells.

Advantages of geothermal energy

It is a clean energy.
It minimizes the use of fossil fuels and the carbon footprint of its operation.
Minimal generation of waste and toxic gases

Committed to a sustainable future

At Enel, we take pride in leading the transition to renewable energy sources in Chile and around the world. The Cerro Pabellón geothermal plant is a testament to our commitment to innovation and sustainability, demonstrating how we can responsibly use natural resources to generate clean and reliable energy. With projects like this, we continue to move toward a greener and more sustainable future for everyone.