Upgrade of “Pumped-Storage Power Plant Etzel”, Feasibility Study

The existing “Pumped-Storage Power Plant Etzel” of the SBB is connecting the „Lake Sihl“ with the „Upper Lake Zurich“.The Power Plant is very important for the power supply for the Greater Zurich Area. The 80-year concession expires in 2017 so the SBB needed to plan the reconstruction and expansion of the power plant.

Feasibility studies for several options of upgrading and rebuilding the 16.7 HZ as well as the 50 Hz generation turbines with frequency converter have been carried out:

  • Complete newbuild of the scheme containing 3 new machine groups (app. 525 MW)
  • Combinations of new installation and continuous production/partly replacement of the existing plant with 4 machine groups (app. 500 MW) or 3 machine groups (app. 250 MW)
  • Continuous production/partly replacement of the existing plant with 7 machine groups (16.7Hz, app. 140 MW) and 2 machine groups (50Hz, app. 150 MW)


Swiss Federal Railways (SBB)


IM Maggia Engineering Ltd and IUB Engineering Ltd in association

Construction period

Project Duration: 2013–2014

Construction costs

Project Costs: CHF 250 Mio to CHF 1'000 Mio (depending on chosen upgrade option)

Scope of services

Feasibility study with different upgrade concepts