Allgmeine Informationen zum Projekt

Illwerke VKW has built a new hydroelectric power station on the Dürrenbach in the municipality of Au, on the border with Schoppernau.

The aim of the power station project, which is due to be completed in 2023, is to make the best possible use of water to generate energy.

To this end, the water will be collected in the area of the uppermost existing bedload dam and conveyed to the power plant site via an approximately 900-metre-long pressure pipe laid in the ground. The powerhouse has been built on the edge of a small forest in an open meadow. Access to the building is via the existing road and a newly constructed path along the edge of the forest. The ideal location, safe from flooding, allows the penstock to be laid in a straight line.

The powerhouse, with a footprint of 9.4 x 9.9 m, houses the heart of the plant: a machine set consisting of a Pelton turbine and a generator with an output of around 1 megawatt. A technical feature of this ingenious powerhouse is the innovative tent roof, which can be easily removed and stored next to the building. This makes it easy to lift the generator in and out. The plans for the power station are based on our master plan for the energy autonomy of Vorarlberg, which envisages the consistent and sustainable use of our hydropower resources in Vorarlberg. The project on the Dürrenbach in Au is a prime example of the sensible regional and natural use of the power of water,’ says Helmut Mennel, former technical director of illwerke vkw AG. A particular challenge at the Dürrenbach is the bedload management. During heavy weather, the river carries a lot of sediment. For this reason, the water is taken in using a tried and tested Tyrolean sluice with automatic screen cleaning and a downstream Coanda screen.

Construction took place in two phases. The water intake and powerhouse were built in parallel. The penstock was constructed in a second phase to avoid the need for construction traffic to use the existing access road and penstock route. The outlet structure was constructed during a low water period in the Bregenzer Ach. For this purpose, the excavation pit in the Bregenzer Ach was filled as a temporary water retention dam and then dismantled.

Construction took around 11 months, and on 10 February 2023 the power station was able to supply electricity to the grid for the first time using hydroelectric power. The project cost around 5.6 million euros,’ says Christof Germann, chairman of the board.