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The plant
The "Valle Secolo" geothermal power plant in Larderello
The "Valle Secolo" geothermal power plant is the largest of its kind in Europe. With nearly 120 MW of installed capacity, it is the most important in a series of geothermal power plants that are concentrated in a small area near Larderello, a hamlet in the municipality of Pomarance (near Pisa) in Tuscany. The area straddles the provinces of Pisa, Siena and Grosseto. There are 34 plants altogether, with 37 generating units and a total capacity of about 800 MW. The "Valle Secolo" power plant is located in a rural area of about 10 hectares to the west of Larderello, 2 km from the village of Montecerboli, near Castelnuovo Val di Cecina. The plant came into operation in the early 1990s. It was designed by the architect Giancarlo Rossi, who envisioned a structure with a distinctive profile which at the same time would also be streamlined and modern.
Technological Features
The power plant consists of two identical sections, each with a capacity of 60 MW: Valley Century 1 and Valley Century 2. Each section features: a single-body, double-flow condensing steam turbine coupled to a two-pole synchronous alternator, (voltage 15 kV), a direct-contact condenser, a multi-stage centrifugal type incondensable gas extractor, and hybrid (wet/dry) type forced draft cooling towers. The geothermal steam passes from the production wells into the power plant through steel pipes known as "vapor ducts."
Tecnology
Geothermal
Status
Operational
Operating capacity
117.6 MW
Energy production
854 million KWh/year
Average production achieved in the last three representative years.
CO2 emissions avoided
391,588 tons per year
Energy needs
316,000 households
Timeline
Milestones
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Impact on local communities
The integration of the power plant, the steam pipelines and the aqueducts necessary for its operation into the landscape is the result of careful design. The plant was built and subsequently upgraded according to the best environmental standards in the industry.
A series of automatic control units enables continuous air quality detection in the residential areas in Castelnuovo Val di Cecina, Larderello and Montecerboli. The production cycle does not require any withdrawal of surface water for cooling. The only water resource is from the geothermal process and consists of about 40% of the geothermal steam condensate, which is reinjected into the geological formation of origin, without any contact with the surface water table. In all geothermal areas, reinjection is subject to real-time microseismic monitoring, thus contributing to the safety and environmental control and management of the area.
Visits
A tour route has been set up inside the power plant which, with prior permission, enables visitors to find out more about the system of electricity production from geothermal sources. In Larderello, it is also possible to visit the Geothermal Museum, where a high-tech interactive tour tells the story of the Earth's energy and its applications.