Hydropower: A storable energy

Hydropower is the most important source of renewable energy in Switzerland. About 60 percent of the electricity in Switzerland is produced from it. That is around 36.5 TWh of electricity per year. Almost half of this comes from over 80 reservoirs and the associated power stations. They act like a large battery. A new, interactive map shows the energy potential of these lakes.

As the largest producer of renewable energies, Axpo operates many storage power plants in Switzerland. Storage power plants have several advantages. Usually located in the Alps, they hold back the water in reservoirs at higher altitudes. Taking advantage of the difference in altitude and under great pressure, the stored water is discharged to turbines located in the valley below, which drive an electricity generator. In this way, they can adjust their production to the daily and annual demand and produce valuable peak energy. Where the Axpo storage power plants are located can be seen on this map.

These storage lakes can be used like a large battery. In Switzerland, they are primarily tapped in the winter half of the year and supply valuable winter electricity. Together with other CO2-free energy sources such as solar, wind and nuclear power, they ensure a sustainable and secure supply of electricity in Switzerland.

Power station Löntsch

So next time you go swimming or hiking in the idyllically situated Klöntalersee, instead of looking at the wonderful reflections of the mountains, take a look through your energy glasses. That is also very exciting. The original natural lake, which was created by a subsidence and a rockfall, was dammed up with an earth dam to form a reservoir. It is located in the canton of Glarus at an altitude of 848 m above sea level and has a length of 5 km and an area of about 3.3 km².

The lake is part of the hydroelectric power station on the Löntsch, whose headquarters are in Netstal. It is a high-pressure storage power plant, which was built between 1905 and 1908 and completely renovated in 2016. The power station uses the outflows of an 83 km2 watershed around the Klöntalersee. It supplies around 119 GWh of electricity per year. The energy content of the reservoir is 34 GWh, and the proportion of energy that can be stored is 29 percent. (more information here)

Energy Battery Switzerland

At present, storage power plants in Switzerland are capable of retaining a maximum of 8.85 TWh of energy, which corresponds to almost 30 percent of Swiss electricity consumption in winter. The storage possibilities of the individual hydropower plants vary. They differ according to topology and historical development. For example, Axpo's Linth-Limmern power plants, with the newly constructed Limmern pumped-storage power plant and the Muttsee and Limmernsee storage lakes, have an energy content of 332 GWh, while the proportion of energy that can be stored is 89 percent. This information can be found on a new storymap from the Swiss Federal Office of Energy.

The interactive map shows which storage lakes can store how much energy. It also shows the annual electricity production of the associated hydropower plants and the relationship between production and storable energy is shown graphically.