Hydro Power Our effort for a sustainable future

Axpo’s experience of hydropower goes back more than a century. Between 1905 and 1908, the Löntsch high-pressure storage power station was constructed in central Switzerland by Motor AG of Baden, one of Axpo’s predecessor companies. In 1914, the plant was taken over by the newly founded Nordostschweizerische Kraftwerke AG, which has been part of Axpo since 2009.

Together with the Beznau hydraulic power station in the canton of Aargau, the Löntsch power station marked a significant milestone in the early 20th century energy world, establishing the first interconnected operation between a high-pressure storage and low-pressure run-of-river hydropower station. This ground-breaking integration significantly improved the overall efficiency of the region’s power generation and use of energy.

Today, with our hydroelectric power plant portfolio of around 60 owned and co-owned plants, Axpo is Switzerland's largest producer of hydropower. 



electricity produced annually by our hydropower plants – 1/6 of Switzerland's annual consumption



longest gravity dam in Switzerland at our Limmern pumped storage plant


million cubic metres

storage volume of Lac de Mauvoisin, one of the largest reservoirs in Switzerland


Today Axpo is Switzerland's largest producer of hydropower with its hydroelectric power plant park (owned and co-owned) comprising around 60 plants. 

Hydro Projects

The Limmern pumped storage plant (LPSP) is one of the most impressive plants in our portfolio. It not only stores and turbines pumps water but can also store surplus electricity from the grid and transfer water from Lake Limmern to Lake Mutt, 2,500 metres above sea level. If necessary, this stored water can be re-used to generate electricity, making the LPSP function like an enormous battery. Watch some breath-taking footage of the LPSP and other Axpo hydro assets.

An overview of hydro power

There are various types of hydro power plant. The most common is the so-called run-of-river plant, built on a river and using the energy of flowing water. A storage power plant, on the other hand, has a large reservoir and uses the gradient between the reservoir and the power plant to generate energy, the water flowing through large pipes or tunnels to the lower-lying power station where it drives the power generating turbines. A tidal power plant uses the power produced by the ebb and flow of the tide to generate electricity.

Run-of-river power plants use the flow of a river to produce electricity. They usually have what is termed a low head – the vertical height between water intake and discharge – and are located where there is a large volume of flowing water.

The incoming water, from upstream, is directed to the turbines. The kinetic energy generated by the flow drives the turbines, which convert this energy into electricity via generators. The electricity is then fed into the grid, while the water used to generate electricity is returned to the river downstream.

Run-of-river power plants produce base load energy and, in contrast to storage or pumped storage plants, cannot adjust the quantity of electricity as and when required. The amount of electricity produced depends on the flow and velocity of the river waters.

Small-scale hydropower plants, usually run-of-river, have an output of less than 10 MW. Often, in addition to generating electricity, run-of-river power plants serve as flood protection. Locks and fish ladders are also installed to enable the passage of shipping and fish.

A storage power plant is a hydroelectric facility that stores water in a reservoir and uses it to produce electricity as and when required. The plant uses the difference in height between the reservoir and the lower engine house to generate electricity.

Water from the reservoir is fed to the turbines through pressure pipes. The resulting kinetic energy drives the turbines, which convert the energy into electricity via generators and feed it into the power grid. The water used to generate electricity is drained, usually into a river.

As a rule, storage power plants are not in continuous operation. Instead, their task is to store water, which is produced in different ways as a result of the weather. Storage power plants come into operation when electricity consumption is at a peak due to daily or seasonal fluctuations. This makes storage power plants important suppliers of flexible peak energy, especially during the winter.

Like storage power plants, a pumped storage plant generates electricity by feeding water from the reservoir to its turbines through pressure pipes. The resulting kinetic energy drives the turbines, which convert the energy into electricity via generators and feed it into the power grid. After turbine operation, the water reaches the lower reservoir.

In contrast to pure storage power plants, however, pumped storage plants do not just generate peak energy. They can also convert excess electricity, which occurs during so-called off-peak periods, into valuable peak energy. To do this, they pump water from the lower reservoir back up to the higher reservoir and reuse it for electricity production at a later point in time. In this pumping mode, the generator works as a motor. It is supplied with electricity from the power grid.

Pumped storage is a proven method of balancing a power grid’s supply and demand in an environmentally responsible and economical way. Pumped storage plants play an important role in ensuring security of supply and stabilising electricity networks.

Find out more about our hydropower in Switzerland

We ensure a sustainable future through innovative energy solutions. Find out more.


Axpo is driving the digital transformation of hydropower by enhancing operational efficiency and maintenance practices. Our approach includes comprehensive digital support, computer-aided analysis using sensor data, the use of drones for inspections in challenging areas, and data-driven decision making. Axpo’s Hydro 4.0 pilot project tested various applications to assess their cost-benefit potential and the opinions of our employees. This allowed us to make informed decisions on the implementation of digitalised operational solutions. In addition, Axpo Hydro Digital is now able to share our expertise and assessment of their value with our partners and customers.

Fish protection

Many fish species use various habitats during their life cycle and therefore need to migrate through bodies of water. The installation of fish ladders and bypasses means that, despite the presence of hydroelectric power stations, fish are able to move up and down rivers and access different habitats. Currently, Axpo is developing a number of large and small fish migration projects.

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