La Coche dam

This route culminates at the impressive La Coche dam, which is 33 metres high. Its major reservoir is supplied by 28km worth of galleries which capture the affluents of the Isère; water intake is particularly high during snowmelt season. The dam is connected to the lower Aigueblanche reservoir and La Coche hydroelectric power plant, according to the innovative principle of a STEP, which stands for Pumped Energy Transfer Station. The principle is straightforward: to generate electricity, the water from the lake upstream (La Coche) is channelled through turbines then delivered to another lake downstream (Aigueblanche). In low water periods, the water is pumped back up to the reservoir upstream thanks to reversible turbines. Potential energy reserves are thus re-established, which can be harnessed at any time to meet peaks in consumption.The new power plant, fitted with a Pelton wheel, the most powerful turbine in France, which was inaugurated in 2019, can increase its power by 25%. It has an annual output of about 100 GWh, the equivalent of 265,000 inhabitants' energy consumption (i.e. covering more than 60% of Savoie's population).