The old Aragonese county of Ribagorza, which straddles the Spanish side of the Pyrenean mountains, has well cared for the abundant rivers that rush over its falls and ridges. These continue to provide the mighty currents so perfect for producing hydroelectricity.
The River Ésera is one of these powerful sources. Back in 1912, the Catalan Gas and Electricity company honed in on the river to supply energy to textile factories on the outskirts of Barcelona and decided to embark on an epic project to build the Seira hydroelectric power station near the village from which it takes its name.
The installation of this plant was a milestone for the area, until then out of the reach of modern transport means. It drew many workers, who were to populate a new industrial colony in the high mountains of the Pyrenees, with their library, church, school, hostels and subsequently all the social and political organisation typical of many a Spanish village. Seira was also a national milestone, since the hydro station represented a civil engineering work without precedent at the time. And it wasn’t without its complications, due to the First World War and orographic and climatological conditions in the area. In 1918, though, the station was finally switched on, producing clean energy from the water it returned intact to a river that continued its journey downstream in search of the protection of the River Ebro.
One hundred years later, this perfectly conserved, and relatively little known, marvel, continues to generate electricity. Operated by ACCIONA since 2009, it does so reliably, efficiently, safely and sustainably, connected to the national electricity grid. The odd outage aside, it has never ceased to serve. Seira was conceived to challenge the passing of time. It is more than a hydro station. It is a legacy.
It’s not difficult to imagine the hive of workers, load-carrying animals, and steel girders springing up, around Seira between 1912 and 1918. Newspapers proclaimed the jobs that were available for experienced miners and carpenters. The works to build the station, and power line to transport electricity to Catalonia (through 273 km of cables and over 2,000 metal towers), was responsible for bringing together around 2,300 workers.
Parts and materials for the turbines and water galleries were transported using animals. Barracks also had to be built to lodge all the workers and they and their families needed services such as a school, church, canteen and cinema, all built in a Swiss mountain style quite distinct from the traditional housing in the area. Seira hydro station brought modernity to the area and a new urbanism to its landscape.
Building the power station was altogether a different kettle of fish. The task of bending those mighty rocks to human will was done through brute force, pick, shovel and dynamite, as they tore down the crags. The works included the excavation of a tunnel over 8 kilometers long, to feed water to the station, the laying of a 4 km rail line over the Ventamillo gorge, cementing the foundations of the Vilanova dam, and installing a penstock over a kilometer long, with a head of 146 m.
Don’t forget here that we were in the second decade of the 20th Century, the years of the Great War and the supply blockades that came with it. Materials and parts for the station came from Switzerland, above all steel and copper, and the First World War saw their prices shoot up and progress was racked with delays, since they had to be transported across land occupied by foreign troops right down to Huesca.
The First World War saw their prices shoot up and progress was racked with delays
Seira hydro station entered into service on 6 August 1918. It hasn’t stopped operating since. Although the station has had a facelift, it conserves all the basic elements of the original construction - buildings, pipework, crane, almost all the main components except the electrics. It is now automatically controlled from the ACCIONA Renewable Energies Control Center in Pamplona, who coordinate with the on-site team that still maintains the station.
The main building has a medieval air about it, almost palatial. Its interior, with a single aisle, seems made for dances and masked balls, but in fact hosts what are now the plant’s relics: three Francis-type turbines which continue to convert the kinetic energy of falling water into the rotational energy used to generate electricity.
La central del Seira produce el consumo eléctrico equivalente a 20.000 hogares y evita la emisión de 76.000 toneladas de CO₂
Seira today produces an average of 80 gigawatt hours (GWh) a year, equivalent to the electricity consumed by around 20,000 homes, and avoids what would be atmospheric emissions of 76,000 tonnes of CO2 from an equivalent coal-fired power station.
The process to generate electricity from the station begins at Vilanova dam, where 24 cubic meters of water per second are diverted toward a pressure gallery with a 9 km head, which discharges into a deposit and feeds, through a pressure turbine, the three horizontal-axis Francis machines. These spin the generators, otherwise known as alternators, which together produce power worth 36.7 megawatts (MW). The voltage of the electricity generated is increased in the plant’s transformers, from 11 kilovolts (kV) to 110 kV, before injection into the electricity grid. The water exits the turbine and is returned unscathed to the river.
Seira has learned by rote the rite of borrowing water from the Ésera to convert the ferocity of its currents into clean, sustainable energy, returning it untarnished to the source from which it came. It has been doing so for over 100 years, with ACCIONA operating it for the last decade (since 2009). Heritage made possible by all those who worked to keep it going in the past, and those who continue to protect its legacy today.
Sources: ACCIONA, La Central Hidroeléctrica del Seira, Europa Press, TICCIH, Ayuntamiento de Seira
The hydroelectric pumping station at Ip, built and operated by ACCIONA, stores clean energy in order to free it when needed through a high-pressure gallery and pipework with a head of over 900 meters
