High in the Aragonese Pyrenees, in a narrow valley carved out by a glacier, is an artificial lake that acts as a large electric water tank.

The Llauset reservoir is 2,200 meters above sea level, not far from where the Aneto rises to the top of the mountain range that separates France and Spain. This dam is also the highest point of the Moralets hydroelectric complex.

Further down at the head of the Noguera Ribagorzana river is the great Baserca dam. Reaching a maximum height of 86 meters and 330 meters long, the dam took 235,000 cubic meters of concrete for its construction, which Ferrovial participated in during the 1980s. This reservoir has its own power plant for producing electricity, and it is also capable of storing energy for times of high demand.

To do this, the third part of the hydroelectric complex comes into play: the Moralets underground power station. This pumped-storage plant sends water towards the highest part of the mountain with 206 MW of power, defying the law of gravity through an enormous pipe. At the other end, the Llauset reservoir awaits. There, water and, therefore, energy is stored until it is needed. At that time, it goes back through the same structure to the Moralets power plant, where the water’s force is transformed into electricity.

The underground system that connects Baserca, Moralets, and Llauset and supports the hydroelectric complex’s operations broke records in its day. Measuring just over a kilometer long and situated at 45 degrees, a primary reinforced pipe spans a drop of over 700 meters. From its highest point, pressure piping extends for another four kilometers until it reaches the Llauset reservoir. This complex, connecting running under the mountain, are capable of extracting all of nature’s power.