Skiers coming down the Vallée Blanche in Chamonix, France cannot imagine that under their ski tips, at more than 100 meters under the glacier , EDF (the French Electric Company) installed in 1973 a collection system of a stream flowing under the ice to feed a hydroelectric plant . Inside the rock, 500 meters below the ice top, water is captured and fed into a gallery of 1700 meters long, going to a vertical 300 meters high penstock to feed the hydroelectric plant.
However, the glacier retreats from 20 to 50 meters per year … In 2000 , the phenomenon accelerated and sensors were now in the open air, no longer in use, forcing EDF to seek the torrent over 800 meters upstream from the glacier to find an ideal location for the next 20 years . In 2009, new drilling began of more than 3 kilometers of galleries , including one km directly beneath the glacier, and the work was completed in 2011.
The largest power generation is between May and October. La Centrale des Bois can supply domestic electricity to a city of over 50,000 residents, the city of Annecy for example.
Some figures : 200,000 hours and 18,000 round-trips by cable car for this transformation so the central can function in the next 20 years if the glacier does not retreat faster … but global warming and / or weather conditions combined with general pollution, as well as non-negligible factors such as impact of transportation , industry and tourism, all of this contributing to the increased melting rate of glaciers…