The Nant de Drance project involves constructing a pumped storage power station in an underground cavern between the existing Emosson and Vieux Emosson reservoirs, a pair of lakes situated in the community of Finhaut. The power station is designed to generate electricity at times of peak consumption. Water from Vieux Emosson will be channelled through turbine generators to the Emosson reservoir 300 meters below. At night and at weekends, when demand for electricity is lower, the water will be pumped back from the lower to the upper reservoir. Equipped with 900-megawatt turbines, the Nant de Drance power station is expected to generate around 2,500 GWh of peak energy a year.

Water catchment and tunnels under construction
Work was started on the water catchment in Lac d'Emosson in mid-March 2011. The water level of this large lake was reduced for this purpose. Two tunnels, around 10 meters in height and eight meters wide, will channel the water from the reservoir to a cavern deep inside the rock. The work in the almost empty lake will last until the end of May 2011, and completion of the first water catchment is scheduled for November 2011. Blasting work for the water-piping tunnels will last until around 2013.

• Nant-de-Drance Website