The concession for Gösgen hydroelectric station and the Winznau weir runs until 2027. Since the Winznau weir, built in 1917, requires comprehensive renovation work, the owner-operator Atel Hydro AG, a subsidiary of Alpiq Holding Ltd., is seeking to renew the concession in advance of its expiry. Regular inspections have identified a need to upgrade the sluice gates and drives and improve the weir's stability. Atel Hydro AG therefore applied for a construction permit last October. The estimated cost amounts to around CHF 24 million. Upgrading the Winznau weir will extend its useful life far beyond the current expiry date for the hydroelectric station concession (2027).
Interest Group Commission meets on 25 June 2009
Even if the concession project envisages no fundamental changes from the current status, the environmental compatibility of the project must be verified. As is usual in such cases, the canton of Solothurn is planning to set up an Interest Group Commission for this procedure, comprising representatives of municipalities, environmental organisations, expert agencies and other affected groups. The Office for Environment has issued an invitation to an initial discussion on Thursday 25 June 2009.
Current concession runs until 2027
Gösgen hydroelectric station was built as a canal power station on the Olten-Aarau stretch of the River Aare between 1913 and 1917. It utilises the Aare gradient from the Aare bridge near Aarburg up to 250 meters above the road bridge near Schönenwerd, a distance of around 14.5 kilometers. In the 1960s the water rights concession granted by the cantons of Solothurn (93 percent) and Aargau (7 percent) for a period of 80 years was extended to 2027 following a people's referendum held by the canton of Solothurn.
The machine house was fully rebuilt between 1996 and 2000. The eight turbines were replaced by four Kaplan turbines for Alpiq and one machine for the Swiss Federal Railways (SBB). Using the same volume of water and the same gradient, the power station generates around 300 million kWh per year or twelve percent more electricity than before reconstruction. The cost of modernisation amounts to around CHF 200 million.