Penstocks
Penstocks: when the mountain produces electricity
Here, in the steep valleys of the Pays des Écrins, the water doesn’t just roll down the slopes: it works. Since the end of the nineteenth century, penstocks have been transforming this natural energy into electricity. The principle is simple but brilliant: capture water at altitude, plunge it at full speed into inclined pipes, and take advantage of the accumulated pressure to drive turbines.
A LITTLE HISTORY
In L’Argentière-la-Bessée, it was a certain Gilbert Planche who thought big. In 1910, he had a hydroelectric plant built, and imagined a spectacular system to power it: a huge metal siphon that spans the river at the entrance to La Bâtie des Vigneaux. This unusual arch connects the water intakes of the Gyronde to those of the Durance. But be careful, there was no question of filling it in any way: the water had to enter on both sides at the same time to avoid explosion!
The rest of the journey is underground. Galleries dug into the rock protect the water circuit up to four 174-metre penstocks, perched steeply above the plant. Since then, they have been replaced by two larger ones, which are still active today.
Want to see it all up close? Follow the heritage trail in the centre of L’Argentière, where you can admire the pipes still in place. And for a fun dive into this part of industrial history, try the augmented reality tour Falling from the water, via the RendR app.
Where to discover penstocks?
- L’Argentière-la-Bessée : pipes visible from the town centre, heritage trail
- Vallouise valley : aerial siphon visible when arriving from l’Argentière
- Digital journey “Falling out of the water” on the RendR app
- All the heritage points on the Hautes-Alpes Heritage app