Ricobayo I and Ricobayo II hydroelectric power station

Ricobayo, Europe's first large hydroelectric power station

Hydroelectric power Energy storage Operating plants

With almost a century of history, the Ricobayo I and Ricobayo II dams and hydroelectric power stations in Zamora were pioneers in electricity production in Europe. It was not in vain that the reservoir was considered one of the largest on the continent with its 1,148 hm³. Today, both plants have a total installed capacity of 328 MW.

Operating plant

Ricobayo Hydroelectric Power Station

Location Zamora (Spain)
Total installed capacity 328 MW
Annual energy production 590 GWh
Comissioning 1935 and 1999

The Ricobayo reservoir (Zamora) consists of two hydroelectric power stations: one at the foot of the dam, Ricobayo I, and one underground, Ricobayo II. The first of these was a pioneer when it was commissioned in 1935, marking a milestone in the history of electricity production in Europe. The Ricobayo dam, associated with the two hydroelectric power stations, is located in the basin of the river Esla; it is almost 100 metres high, handles a total volume of 1,148 hm³ and its flooded surface area is almost 6 hectares (5,725 ha). As for the hydroelectric power stations associated with the dam, Ricobayo I has a rated power of 174.53 MW, while Ricobayo II has a rated power of 153.56 MW. 

The Ricobayo reservoir and dam, a historic building 

The first project to build the Ricobayo dam, less ambitious than the final one, dates back to 1919 when the civil engineer José Orbegozo created the Sociedad Hispano Portuguesa de Transportes Eléctricos to harness the flow of the River Esla - the largest tributary of the River Duero. Orbegozo wanted to create the largest reservoir in Europe, with some 1,200 hm³, which would allow winter water to be stored and thus have a large regulating capacity

Work began in 1929. The Ricobayo dam would be almost 100 metres high and more than 200 metres long. For this impressive engineering work, a granite quarry of 400,000 m3 and stones weighing up to 2,000 kilos were used, so to carry out its construction, an entire village was built, Salto del Esla, which housed the thousands of workers who were employed in the construction of the dam. Not in vain, in the summer of 1930, the number of workers reached 2,600. Later, the same village took in those who came to work at the hydroelectric power station.



  • Detalle de la presa en construcción 1929 Work begins on the Ricobayo dam (Zamora), almost 100 metres high and more than 200 in length The dam was built with a 400,000m3 granite quarry and stones weighing up to 2,000 kilos
  • Los trabajadores sobre la presa en construcción 1930 In the summer of 1930, the number of workers reached 2,600.
  • October 1930 Visit of King Alfonso XIII.
  • 1935 Ricobayo I is put into operation with an output of 100 MW (only 3 of the 4 units come into operation) and the supply of electrical energy from the Ricobayo waterfall to the north of Spain via the "Esla - Alonsótegui" line at 138,000 Volts begins.
  • 1937 The power station connects with León by means of a 110 km line.
  • 1943 The Hydraulics Laboratory was built, the first R&D facility of its kind, to study a solution to the erosion problem suffered by the plant. Today, it has produced more than 150 tests of reduced models of dams, spillways, tunnels, vortices and yield curves. The solution to the problems in the spillway, a system to break the force of the water, which was studied at the Escuela de Caminos de Madrid.
  • Vista aérea de la presa March 1948 The manufacture of the fourth unit, distinguished from the other three by its alternator, its turbine and by having a lower bridge, came later because the ship on which the machinery was travelling sank as a result of the Second World War and it had to be manufactured again. It was commissioned in March 1948.
  • Gruas trabajando 1991 Construction of the extension begins. A new plant is added to double the installed capacity, Ricobayo II, with 158 MW.
  • Detalle del interior de la obra 1999 Ricobayo II becomes operational.
  • Vista aérea de Ricobayo 2019 90th anniversary of the start of construction of Ricobayo.

 View historical photos of our hydroelectric facilities.

In 1935, the Ricobayo I hydroelectric power station was commissioned with a capacity of 100 MW and began to supply electricity from the Ricobayo waterfall to the north of Spain via the Esla - Alonsótegui line at 138,000 volts. Two years later, in 1937, the plant was connected to León by means of a 110 km line, later multiplying the connections with the rest of Castile and Cáceres. 

At that time, only three of the four units were put into operation. The manufacture of this fourth unit - distinguished from the other three by its alternator, turbine and lower bridge - was complicated by the fact that the ship on which the machinery was travelling sank as a result of the Second World War and had to be rebuilt. As a result, this fourth set was not commissioned until 1948. 

In 1991, construction began on Ricobayo II, a new underground hydroelectric plant, which aimed to double the installed capacity, adding 158 MW. 

Iberdrola, world leader in renewable energies

At Iberdrola, we decided to commit to renewable energies more than two decades ago as a fundamental pillar on which to build our safe, clean and competitive business model. Thanks to this vision, we are today world leaders in renewable energies, reaching 42,187 MW of renewables in operation by the end of 2023.

This commitment is reflected in our record investment plan of €47 billion in the period 2023-2025, of which we will allocate 17,000 million euros to the renewables business. With these investments, we will increase our installed renewable capacity by 12,100 MW to 52,000 MW by 2025 —6,300 MW of photovoltaic, 3,100 MW of onshore wind, 1,800 MW of offshore, 700 MW of batteries and 200 MW of hydro.