PSW Limmern

Limmern pumped-storage power plant

The Limmern pumped-storage power plant (PSW Limmern) in the Canton of Glarus is one of Axpo’s most important expansion projects. The underground plant pumps water from Lake Limmern to Lake Mutt, situated 630 meters higher up, then uses it to generate electricity on demand.

The pumping and turbine capacities of the new pumped-storage power plant each reach 1,000 megawatts (MW), increasing the output of the Linth-Limmern power plants from around 520 MW currently to 1,420 MW. This equals the output of the Leibstadt nuclear power plant or the hydro power plant at Cleuson-Dixence.

The first machine group was synchronized with the grid in 2015. Summer 2016 saw the new Lake Mutt dam wall tested against the official storage plan. In the meantime all major project work has been completed. The acceptance of the fourth and last machine group will take place at the end of 2017. Visitor tours for the public will be available as of January 2018.


Unlike pure storage power plants, pumped-storage power plants like that at Limmern can generate their own peak-load energy as well as converting excess electricity generated during off-peak periods into this valuable commodity. This involves pumping water back to the reservoir higher up and then using it later to generate more electricity.

Pumped storage is a tried-and-tested, economical method of matching supply and demand in an electricity grid in an environmentally friendly manner. The Limmern pumped-storage power plant therefore plays an important role not only in ensuring a reliable electricity supply but also in keeping electricity grids stable.

Limmern pumped-storage power plant

Watch a time lapse video of the construction of the Limmern pumped-storage power plant.