Alpiq in: Europe

Story: 02.04.2009

Cleuson-Dixence: Investment in home-grown peak energy

Wiederinbetriebsetzung Cleuson-Dixence

Alpiq has been successfully harnessing the power of water for more than 100 years: the generation of hydroelectricity is efficient and low-carbon. The water stored in our mountain lakes enables the rapid generation of peak energy.

One example is the Cleuson-Dixence facility in the Valais, which can feed the capacity of a nuclear power plant into the high-voltage grid within as little as three minutes. The plant was built by Alpiq (as the majority shareholder) and Dixence SA between 1993 and 1998 at a cost of CHF 1.3 billion. The hydroelectric complex covers the water catchment from the Grande Dixence dam, a 15.8 kilometer supply tunnel, a 4.3 kilometer long pressure shaft and the underground Bieudron power plant (1,200 MW). The Bieudron power plant therefore simultaneously holds three world records: the highest head, the most powerful Pelton turbine, and capacity per pole of a.c. generators.

Following an accident in December 2000 involving a nine-meter line rupture above Bieudron, the plant had to be shut down in order to carry out comprehensive repairs. To this end the owners founded a new company, Cleuson-Dixence Construction AG (CDC), which was tasked with carrying out a full renovation and upgrade of the complex, not only in terms of technology but also in terms of safety and cost-effectiveness. Following a series of geological measurements and technical studies, interior cladding for the ruptured supply line was found to be the most suitable solution. The unsafe rock structure in the accident zone had to be circumvented by a bypass. Pastures, forests and infrastructures were restored in conjunction with the local municipalities.

Recommissioning scheduled for the beginning of 2010

On 2 April 2009, the last pipe was transported to the construction site. The shaft consists of 408 pipes, i.e. 1,360 elements and 12,500 tonnes of steel. The welding operations were completed in May and coating work has been in progress since April 2009.

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