Pumped storage hydropower plant Nant de Drance

Hydroeletric power plants, undergroud works

Project

Underground construction of a 900 MW pump storage power plant. The facility includes 2 water intake/restitutions into Lake Vieux-Emosson, 2 inlet tunnels with valve chambers, 2 waterfall wells, an underground power plant with 6 machine groups, Francis type, 150 MW each, an underground transformer station, a downstream valve chamber and 2 lower tunnels with outlet structures into Lake Emosson.

Technical data

• Flow rate: 240 m3/s
• Drop height 250/375 m
• Inlet shafts D = 6.6m; L = 2 x 277 m
• Vertical shaft D = 6 m; H = 2 x440 m
• Upper valve chamber: LxWxH 60 x 15 x 18 m
• Underground turbine power plant: LxWxH 195 x 32 x 52 m
• Transformer plant: LxWxH 132 x 18 x 14 m
• Lower valve chamber: LxWxH 64 x 12,5 x 12 m
• Headrace channel: D = 6,60 L= 2 x 1230 m
• Supply and return work to the 2 lakes
• Various access tunnels (total 17 km)

Total cost

About CHF 1,900,000,000

Timeline

2008–2020

Customer

Nant de Drance SA

Services provided

• Support of the project management in the concrete work of machine and transformer caverns.
• Administrative support of the project management in contractual matters.
• Auxiliary construction management for ABAG, responsible for the finishing work