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Montafon Rellswerk

Vandans - The latest pumped storage power plant in Vorarlberg has been in operation since the middle of last year. The plant enables peak and control energy production to be increased and is an important part of the Obere Ill-Lünersee plant group.

Die Bauarbeiten beim Montafoner Rellswerk in Vorarlberg wurden schon fertiggestellt.

© Nägele Hoch- und Tiefbau

The construction work at the Montafon Rellswerk in Vorarlberg has already been completed. © Nägele Structural and Civil Engineering

After extensive planning work, construction work on the Rellswerk 2014 was able to begin by Vorarlberger Illwerke AG. The aim is to generate electricity exclusively from hydropower and other renewable energies. The gradient of the upper Rellsbach can now be optimally used for the Lünerseewerk.

The main function of the Rellswerk is to supply water from the inlets of the upper Rellsbach stream to the drive water system of the Lünerseewerk.

This is intended to increase the water resources of the Lünerseewerk. The water from the inlets is temporarily stored in an equalizing reservoir, pumped via a pressure pipe into the Lünersee-Latschau water channel and pumped further into the Lünersee. Around 17 million cubic metres are pumped into the lake every year.

Equalizing reservoirs

A reservoir was built for the new Rellswerk. ARGE Rellswerk Vandans, which includes the PORR subsidiary Nägele Hoch- und Tiefbau GmbH, was commissioned with the construction work on this compensating reservoir. The compensating reservoir has a utilisation volume of 44,000 m3 . The shaping of the basin and the design of the bank areas were implemented very close to nature.

In the course of the construction work, the Rellsbach was diverted and now runs along the foot of the dam. The maximum static dam height is about 14 m.

Machine building

The construction of the nacelle, which was to be integrated into the upper section of the artificial dam, was even more complex than the construction of the equalizing reservoir. After completion of the building, only the access portal is visible from the outside. According to the wishes of the operators, the entire plant should remain as undetectable as possible. The majority of the hydropower technology is located underground.

The plant is not accessible in winter and therefore runs completely without any maintenance.