Nant de Drance SA is building a pumped storage power station in the Valais municipality of Finhaut. The facility will be situated in an underground cavern between the existing Emosson and Vieux Emosson reservoirs. The power station is designed to generate electricity at peak consumption times and to balance out the irregular and variable electricity generation from renewable energy sources. Work on excavating the underground machine cavern has been under way since mid-2012. The dimensions are impressive: 190 meters long, 52 meters high and 32 meters wide. The excavation should be completed in March 2014. The work to raise the height of the Vieux-Emosson dam was started in the spring of 2013. After completion of the construction work, which will take another two years through to the autumn of 2015, the dam will have gained 20 metres in height. The structural steelwork and the installation of the machines will be started in 2014. The commissioning of the power station will take place in stages from 2017.

Open-loop Pumped Hydro Storage