14 Place St Jean, 73110 Valgelon-La Rochette, Auvergne-Rhône-Alpes, France

La Rochette

La Rochette hydroelectric power station exploits the Gelon torrent. It houses 2 Pelton turbines and develops a power of 2,600 kW.

  • Intake altitude level: 657 NGF
  • Restitution altitude level: 348.5 NGF
  • Gross head: 308.5 m
  • Maximum water flow taken: 4 m3/s
  • Maximum gross power: 3020 kW
  • Maximum electrical power: 2600 kW
  • Average annual production: 10 GWh/year

The first FMG power plant

The Gelon hydroelectric power plant in La Rochette is a work initiated by Louis-Albert Convert. Built from 1965 to 1968, it is the first power plant of Forces Motrices du Gelon. The two sites of the Gelon power plant (water intake and power plant) are located on the site of old mills: La Martinette mill, in the town of La Table and the Pompée mill, at the exit of the Gelon gorges, in the city center of La Rochette. The penstock now connects the two sites to ensure energy production.

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The Gelon, a snow and rain river

The Gelon is a mid-mountain river. Its source is at an altitude of 1,316 m, in the peat bogs of Montgilbert. It then flows for about 30 km before finally emptying into the Isère River at Chamousset.

Its regime, upstream of the water intake, is determined by the rains but also by the snows, the upper parts of its catchment area reaching 2,076 m, at the summit of Chapotet mountain (Belledonne Massif).

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Clean energy

The Gelon hydroelectric power plant in La Rochette produces 10G Wh per year.

A thermal power plant would consume 2,220 tons of oil and release 8,330 tons of CO2 for the same energy produced, the equivalent of the domestic consumption of 3,000 individuals.

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