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Energy in motion

Originally a three-kilometre-long lake, Schluchsee was formed about 10,000 years ago during the last ice age in the course of the glaciation of the Feldberg region. The water level was raised by about 30 metres following the construction of this dam in the upper Schwarza Valley between 1929 and 1932, creating a 7.5-kilometre-long reservoir with a maximum active storage capacity of 67.2 million cubic metres of water. It serves as an annual storage reservoir for the Schluchsee Power Plant Group with its plants in Häusern, Witznau and Waldshut. At the same time, it is the upper basin of Häusern upstream plant. Besides the natural tributaries from the 72-square-kilometre catchment area of the Feldberg massif, the lake is also filled by pumping water up from the Rhine across the three power plant levels. The barrier at Schluchsee is a gravity dam made of concrete with embedded granite blocks. Safety is monitored by constantly taking measurements. The structure weighs 285,000 tonnes and is 240 metres long. It is 63.5 metres high at its tallest point (27 metres of which are invisible beneath the ground) and has a crest width of 3.7 metres.

Energy transition

Being able to store electricity in large quantities and generate it within seconds when needed is now more important than ever. The sun and the wind have long been playing their part in generating electricity in Germany and are producing an ever increasing share. Yet these generation sources fluctuate depending on the weather and are unreliable. Pumped-storage power plants come into play when too much electricity overloads the grid or a lack of electricity threatens the supply. They work within seconds, produce zero emissions and generate outputs that rank them among the best of all available storage technologies.

How pumped-storage power plants work

Pumped-storage plants consist of an upper and lower basin. Between them are power plants, which pump water uphill if there is excess electricity and allow it to flow down again through turbines to generate electricity when power is needed. They are precisely tailored to meet the needs of the grid at all times. As such, they help to secure the supply – cleanly, effectively and reliably.


Schluchseewerk AG

With its five pumped-storage power plants, Schluchseewerk AG is one of Europe’s largest suppliers and leading experts. As a partner to its shareholders, it oversees the safe and reliable operation of all its facilities, thereby helping to stabilise the power grid and playing its part in safeguarding the energy supply for today and tomorrow. Schluchseewerk AG – peak power permanently!

Schluchsee Power Plant Group

The three pumped-storage power plants managed by the Schluchsee Power Plant Group – Häusern upstream plant, Witznau intermediate plant and Waldshut downstream plant – store and generate electricity with water that is moved between Schluchsee and the High Rhine. This water, along with the water from the natural tributaries of the eastern Feldberg region, is primarily used to generate eco-friendly reserve electricity for the European power grid.

Facts and figures

  • When the reservoir is full, the water surface of Schluchsee covers 514 hectares – roughly equivalent to the area occupied by 720 football pitches.
  • It would take more than 11,000 years to fill Schluchsee with water using a garden hose.
  • One metre of the upper Schluchsee water level is equivalent to a storage capacity of 6.5 gigawatt-hours of power. This equates to the battery storage volume of more than 130,000 electric cars.
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