Cortes-La Muela Reservoir

Cortes-La Muela Reservoir (sometimes referred to as Cortes II Reservoir) is an arch dam and hydroelectric project built on the mid-course of the Júcar River, located in the town of Cortes de Pallás, within the province of Valencia, in the Valencian Community, Spain.[1]

As of 2018, it was the largest pumped hydroelectric storage plant in Europe. The project comprises a dam and large reservoir, a conventional hydroelectric power station and two underground pumped-storage hydroelectric power stations that, together, generate approximately 5000 GWh per annum.[2]

Description

The Cortes Reservoir and dam, together with La Muela I hydroelectric power station, were built between 1983 and 1988. The pumped-storage hydroelectric power station has an installed capacity of 630 MW for generation and 540 MW for pumping.

Later, between 2006 and 2013, La Muela II pumped-storage power station was constructed,[3] with an installed capacity of 850 MW for generation and 740 MW for pumping. This established the complex as a major hydroelectric facility within the Iberian Peninsula, with 1520 MW in pumping capacity. The reservoir covers an area of 115 ha and has a capacity of 116 hm3.[4] The combined facilities were estimated to cost 1.2 billion EUR.[5]

The complex comprises three hydroelectric power stations: the conventional station located at the foot of Cortes II Dam, La Muela I, and La Muela II. The distinctive feature of La Muela II is that it was designed to use electricity at night and generate it during the day. At night, when electricity demand is low, water is pumped from Cortes Reservoir up to La Muela Storage Basin using surplus electricity from the grid, as electricity production at night exceeds consumption.[1] During the day, when households and businesses consume more electricity, the water is released through turbines, falling 524 m from the storage basin back down to the reservoir, producing clean electricity. In 2022, due to the rapid growth of photovoltaic energy, electricity surpluses began to occur during the central hours of the day, meaning that most pumping is now carried out at that time.[6]

La Muela II power station is located inside an underground cavern measuring 115 m long, 50 m high, and 20 m wide; larger than Valencia Cathedral. La Muela II has a 840 m penstock that is 5.45 m in diameter, with an intake in the 23 hm3 upper reservoir, an underground plant to house the equipment and a suction area in the lower reservoir.[1][2][7]

The current reservoir and power station facility replaced an earlier power station dating from the 1920s, known as Cortes Hydroelectric Power Station, or Rambla Seca. It was demolished in 1988 once the new facilities were operational.

See also

  • List of dams and reservoirs in Spain
  • Renewable energy in Spain

References

  1. Hydroelectric power plants in the Júcar river basin Iberdrola, 2025, retrieved 22 September 2025^
  2. Patel, Sonal. Spain Inaugurates 2-GW Pumped Storage Facility Power, 2013-12-01, retrieved 2026-02-28^
  3. Iberdrola inaugura la mayor central hidráulica de bombeo de Europa Público, 14 October 2013, retrieved 22 September 2025^
  4. Cortes-Muela: the Largest Pumped-Hydro Storage Plant in Europe European Association for Storage of Energy (EASE), 6 August 2018, retrieved 22 September 2025^
  5. Kramer, Julia. Inside La Muela: Europe’s largest pumped storage hydropower plant Enlit, 2025-03-24, retrieved 2026-02-28^
  6. Así es cómo el bombeo ha abandonado la noche y genera ahora más en las horas solares El Periódico de la Energía, 24 July 2023, retrieved 22 September 2025^
  7. La Muela II (Valencia) Hydroelectric Power Plant Boslan Engineer and Consulting, n.d., retrieved 2026-02-28^