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A natural flow of energy

First used more than 2,000 years ago, hydroelectric energy has always had an important role in the global economy. The Industrial Revolution of the 19th century would probably never have happened without it. The first hydroelectric power station opened in 1870 and Genevan engineers like Théodore Turretini were among the pioneers.
A hydroelectric power station works by harnessing the power of water. The amount of energy generated depends on the height from which the water falls and the available rate of flow. For example, the water that builds up behind a mountain dam releases a lot of energy because it falls a long way. Whereas the water that activates a turbine on a river uses the intensity and speed of its flow to generate power.



Geneva’s hydroelectric energy

There are three kinds of hydroelectric power station: those on rivers that use the water's natural flow; those that work on water build-up (like mountain dams); and finally, turbine pumping stations that pump the water back to its starting point when there’s too much energy in the network and which re-turbine the water when energy demand increases.
Hydroelectric energy has always been a major player in the Genevan energy landscape. In fact, a large part of the electricity consumed during the 20th century was generated by hydropower stations. And the construction of the Verbois dam and SIG’s significant stake in the big Alpine and Valaisan dams are testimony to the richness of this story.

The Verbois power station

Built in 1944, this river dam is the biggest hydropower construction in the canton of Geneva. When it first started operating, the dam provided enough electricity for the entire population of Geneva. Today, it generates about 20% of the canton’s energy needs.
It is also now equipped with a fish pass to let fish swim up the 20 metre waterfall, all the way to Lake Geneva.

Benefits


Hydroelectric energy today

Right now, SIG uses three hydroelectric power stations on the Rhone river (Verbois, Chancy-Pougny and Seujet ) and one on the Arve (Vessy).


In 2011, we bought a 15% stake in Energie Dienst Holding AG (EDH). EDH owns more than 20 dams and our close relationship with the company means we now have enough energy to supply around 15% of the electricity needed by Genevans.

Hydroelectric power in numbers