With 24 GWh storage and 1,780 MW installed capacity, Cortes - La Muela is one of Europe’s largest pumped storage facilities. Pumped storage hydro is the most efficient technology to store large amounts of electricity over long periods of time. This ability helps to manage the variability of renewable sources.
Cortes - La Muela hydro scheme, with 1,780 megawatts (MW) installed capacity, is one of Europe’s largest pumped-storage hydropower plants, located on the Júcar river, near Valencia (Spain).
The complex consists of the Cortes conventional hydro power plant, and the La Muela pumped storage facility, which houses seven reversible turbines in two underground caverns.
The station can use excess power on the grid to pump water from its lower level reservoir to be stored in the upper one, using hydraulic pumps. Then, when energy is required on the system, the water stored in the upper reservoir can be used to generate electricity for customers.
As well as being a reliable facility, with availability exceeding 90%, Cortes - La Muela is an extremely flexible asset. It can generate 1,780 MW of electricity for the grid in less than 5 minutes from standstill. In just 30 seconds, each of its nine units can generate 100 MW. Thanks to it fast response, and its ability to quickly switch from pumping mode to generation mode, it also provides stability for the grid.
Ultimately La Muela helps to make the most of every green megawatt of power generated from renewable sources.
“The La Muela pumped-storage scheme has a crucial role to play to support the energy transition. It stores excess energy on windy and sunny days, that could otherwise be lost, and it can quickly provide power for homes and businesses when they require it."
“Pumped-storage also helps to keep the grid system stable. Power output produced by the wind and sun can change quickly, but fast and flexible stations like Cortes - La Muela have the tools to help keep the system secure.”
Javier López Nieto
Head of Mediterranean Generation at Iberdrola
This type of power station utilises two reservoirs at different altitudes, allowing water to be stored when demand is low and then used to generate energy during peak consumption times, in order to balance overall electricity demand.
During off-peak hours, typically nights and windy days, excess generation capacity is used — which also has a lower market cost — to pump water from the lower level (1) reservoir to the upper one by means of hydraulic pumps that propels the water through a penstock (2) and conduction tunnel structure. The upper reservoir (3) acts as a storage facility, where energy is stored as potential energy.
At peak hours, i.e. daylight hours or days with low renewable output, the pumping station functions as a conventional hydroelectric plant. Water accumulated in the upper reservoir (4) is sent to the lower reservoir through the conduction tunnel (5). Water potential energy is transformed into mechanical energy in the hydraulic turbine (6), this mechanical energy is transformed in electrical energy in the generator (7), then this electric energy is sent to the grid where it is instantaneously distributed to consumers.
Pumped hydroelectric plants thereby offer efficient and long-term energy storage, and facilitate the integration of renewable energy into the system.
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