The Sil river basin, a journey to the beginnings of the energy sector

A trail of melted snow soaks the entire slopes of the Peña de Orniz, on the side that falls down towards the regions of Babia and Laciana between León and Asturias. Spring is on the way, but the sky is overcast and cold winds still blow strongly between the peaks of the Cantabrian mountain range. Drop by drop a torrent is formed that is launched towards the plain that can be seen on the horizon. The water starts to flow quickly and starts shaping the terrain when it reaches the town of Villablino in León. This endless trickle becomes the Sil basin, an ecosystem of a beauty difficult to replicate and that has played a strategic role in the energy sector in Spain.

At the beginning of the last century they began to open up the coal deposits in the river basin. A company called Minero Siderúrgica de Ponferrada (MSP) opened most of the mines and completely transformed a landscape that until then had been shaped by agriculture and livestock. Suddenly, incipient industrial development led to the creation of modern infrastructures, including the railway line between Villablino and Ponferrada, which encouraged growth in the area as a result of new business projects involving the mineral. 

This universe of economic opportunities included the riverbed itself, but the impetus was dampened mainly with the construction of the Bárcena and Las Rozas dams. The tons of concrete raised the water level until it became a canyon in a series of forests full of oaks, beech, ash, willow and yew trees through where it is easy to come across brown bears, capercaillies, lynxes and otters just by simply taking a stroll there.

But if there is something really overwhelming with regard to some of the places left behind by the water on its long journey to the sea, it is the shocking silence. Not because of an absence of noise, but because of minimal intervention by human beings in the generation of those natural sounds that surround you like in a home cinema.   

The sheet of a pale blue that extended next to Bárcena had a number of uses including as a refrigerant for the Compostilla II thermal power plant, the second most important in the country after As Pontes, with more than 1,300 MW of installed power and that took over from Compostilla I, which was the root of Endesa. When it was opened, Compostilla consumed the coal that was mined in the basin itself in Laciana and El Bierzo, but increasingly strict emission control requirements opened the door for imported fossil fuel that was less polluting.

From the Las Rozas dam to Bárcena, hydroelectric installations were quickly built that were used to get maximum performance from the enormous power coming from the already distant traces of melted snow from the Peña de Orniz. The Ondinas, Peñadrada, Cornatel, Quereño, Bárcena, Santa Marina I and Santa Marina II power stations together exceed 400 MW of installed capacity and are still as important as ever.

In fact, this volume of megawatts is essential for the process of  energy transition towards a society free of polluting emissions and that obliged Compostilla II to be dismantled. So far, hydroelectric is the simplest formula for the planned production of renewable energy and serves as a backup for those other renewables that are non-manageable, including wind and solar energy, which suffer from the ups and downs in the availability they need to keep them operational.

When passing Ponferrada towards Galicia a thin layer of rain becomes endemic and follows the Sil this section that takes it towards a cruel destination. The river rebels for the last time by extraordinary riverbanks with gentle curves and excavating gorges which are so stunning that they have become one of the community's biggest tourist attractions. It is the final twist in a script that postpones its terrible end, because there is nothing worse for a river than not to meet salt water, or to merge with another river.