Geothermal energy: the invisible heat driving Italy

Geothermal energy is the power that comes from beneath our feet. In Tuscany, amid natural geysers and vapors emerging from the earth, geothermal energy is a historic industrial reality that is more relevant today than ever. It is a programmable, continuous renewable source capable of producing electricity 24 hours a day, while also heating homes and supporting the local economic fabric. This supply chain, which began in Italy over a century ago, now contributes crucially to the energy transition.

How it works: "cultivating" energy

The principle is brilliant in its simplicity: harnessing the natural heat accumulated in the deep layers of the Earth's crust. In geothermal fields, high-temperature steam is extracted through wells, channeled along a network of steam pipes, and used to power turbines that generate electrical energy. After use, the exhausted fluid is reinjected into underground reservoirs, closing a sustainable cycle that preserves the resource and limits emissions. This is why professionals in the sector speak of "cultivation" rather than exploitation of these energy deposits.

Geothermal energy distinguishes itself from other renewable sources because it is not subject to seasonality or weather conditions. This continuous and programmable availability contributes significantly to the stability of the electrical system.

The Tuscan heart: from the first bulb to a global model

Tuscany is the beating heart of this technology. It was here, in Larderello, where it all began. While the mineral qualities of geothermal fluids were exploited as far back as the Middle Ages, the turning point came in the 19th century with engineer François Jacques de Larderel, who realized the industrial value of those boron-bearing steam vents (soffioni).

The moment that changed energy history, however, was 1904: Piero Ginori Conti used natural steam to produce electricity, lighting the first five light bulbs in the world powered by geothermal energy. In 1913, the world's first geothermal power plant was born, making Italy a pioneer of a technology destined to spread to countries like Iceland, the United States, the Philippines, New Zealand, and Chile.

A mature industrial system

Today, the district managed by the Enel Group spans the provinces of Pisa, Siena, and Grosseto. It hosts 34 plants and 37 production units with an installed capacity of nearly 1,000 MW. Every year, Tuscan geothermal energy generates between 5.5 and 6 billion kWh—accounting for more than one-third of the region’s electricity needs and 70% of Tuscany's renewable production. These figures make this district one of the most important geothermal sites in the world.

Sustainability and social integration

Modern geothermal energy is defined by its integration into the local social and economic fabric. Beyond electricity, the residual heat exiting the turbines is utilized through district heating networks serving over 13,000 users. Schools, swimming pools, public buildings, and homes benefit from clean energy at reduced costs. Furthermore, local greenhouses and food companies utilize this resource to reduce consumption and increase competitiveness.

The connection with the land also extends to tourism. The "Devil's Valley," winding through Larderello, Sasso Pisano, and Monterotondo Marittimo, has become an educational destination. Visitors can observe natural geothermal phenomena, visit dedicated museums, and take guided tours near the plants—a unique coexistence of science, industry, and landscape.

Over a century after that first light bulb was lit by the steam of Larderello, Italian geothermal energy continues to illuminate the future. It is a resource flowing silently beneath us that the country's ingenuity has transformed into clean energy and growth for entire communities.

This article is also published on Il Tempo, in Italian. illuminem Voices is a democratic space presenting the thoughts and opinions of leading Sustainability & Energy writers, their opinions do not necessarily represent those of illuminem.