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Nant de Drance: The culmination of a one-of-a-kind project

Finhaut, Switzerland – The ninth of September 2022 will remain a significant date for Nant de Drance. The inauguration of this 900 MW pumped storage power plant in Valais, Switzerland takes place today. The event marks the end of a 14-year construction project involving hundreds of labourers, skilled workers and engineers from all over Europe working in a challenging alpine and underground environment. Simonetta Sommaruga, member of the Swiss Federal Council and Roberto Schmidt, President of the Valais Council of State will participate in the official inauguration ceremony. The festivities will be dedicated to today’s youth, future generations and the future of energy.

Assembling a pump turbine. (Photo: Nant de Drance / Sébastien Moret)

Construction of the Nant de Drance pumped storage power plant in the municipality of Finhaut in the canton of Valais in Switzerland officially began on 8 September 2008. Today, 14 years and one day later, the moment has come to inaugurate this monumental piece of work. Over the years, hundreds of workers from many trades have come from all over Europe and even from Asia to work under challenging conditions to build Nant de Drance. At the height of the construction project there could be 650 workers onsite. The alpine conditions at an altitude of 2000 metres made raising the Vieux Emosson dam particularly challenging. Working 600 metres underground, miners excavated some 1.5 million m3 of mountain rocks to create the caverns and tunnels that make up the hydropower complex. This was achieved without any serious accidents – remarkable given the scale of the project. The six pump turbines – each with a capacity of 150 MW and at the cutting edge of technology – were assembled on site in the depths of the mountains and tested over many months for optimal performance.
The plant entered operation on 1 July 2022 and is proving to be extremely reliable. It is characterised by the flexibility and availability of the machines which allow to react very quickly to fluctuations on the electricity grid, and thus to adapt to market demand. Today’s inauguration marks the handover to the Nant de Drance shareholders – Alpiq (39%), SBB (36%), IWB (15%) and FMV (10%) – who have access to the production and pumping capacities of the plant as per their stake and who manage the energy according to market needs, thus helping to stabilise the Swiss and European electricity grid.

A celebration dedicated to the future of energy

Simonetta Sommaruga, Federal Councillor for the Swiss Federal Department of the Environment, Transport, Energy and Communications (DETEC) and Roberto Schmidt, President of the Valais Council of State and Cantonal Energy Minister will today attend the inauguration of the pumped storage power plant. “Nant de Drance can store a lot of electricity and therefore plays a very important role in the security of supply of our country,” says the Energy Minister Simonetta Sommaruga. The Federal Council has also taken various measures in recent months to ensure that Switzerland gets through the coming winter as well as possible.
Given the key role of Nant de Drance in the future of energy, the inauguration of the power plant will be dedicated to the youth of today and future generations. Children from the Trient region will lead a large part of the official ceremony with their musical talents. On Thursday 8 September 2022, pupils from nearby primary schools had the chance to discover the Nant de Drance power plant. This immense construction project is located just a stone’s throw from their homes, the building of which has run alongside their entire childhood. More than 2000 people are expected to visit on the open days on Saturday and Sunday.

Four shareholders united by a common goal

Antje Kanngiesser, CEO of Alpiq, said, “Nant de Drance is defined by its flexibility which allows it to absorb fluctuations due to the intermittent production of new renewable energies on the electricity grid. Managing flexibility is one of our key competencies at Alpiq. Nant de Drance fits into our production portfolio perfectly and contributes to stabilising the security of supply in Switzerland and Europe in a sustainable way. Nant de Drance is a visionary project which is now up to us – in collaboration with our partners SBB, IWB and FMW – to value over the next 80 years.”

Vincent Ducrot, CEO of SBB, said, “Electrical energy is of great importance to SBB, as our trains are powered by electricity. SBB currently operates with a 90 percent share of hydropower – the majority of which is generated by our own power plants. From an environmental perspective, this makes SBB one of Europe’s leading railway operators. However, we also rely on domestic electricity from the 50 Hz grid for our buildings, railways stations and technical facilities. This makes Nant de Drance an important and flexible storage space that will help to stabilise the Swiss and European power grids.”

Claus Schmidt, CEO of IWB, said, “With the Nant de Drance hydropower plant, we are adding another chapter in Swiss energy history. IWB stands for renewable energy. We are already producing more renewable electricity than our customers need. Just under a third of it is based on wind and solar power. That’s why Nant de Drance is such a perfect fit for our sustainable portfolio. It is an investment in flexibility and security. It also helps us stabilise the power grid, which will become increasingly important in the future.”

Stéphane Maret, CEO of FMV, said, “Like our visionary ancestors and the epic story of dam construction in Valais, today we are able to invest with our partners in large infrastructures in the long term for future generations. This is an auspicious moment from the perspective of the huge challenges of the energy transition. Against this unusual backdrop, FMV is responsible for implementing the hydropower strategy at Valais. And the sustainable battery at Nant de Drance is the centrepiece, continually balancing the grid for security of supply in Switzerland.”

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For more information about Nant de Drance, please visit


Nant de Drance SA

Aline Elzingre-Pittet

T: +41 21 341 22 77

Nant de Drance SA in brief 
The Nant de Drance power plant is a pumped storage power plant with a capacity of 900 MW in a subterranean cavern located between the two reservoirs of Emosson and Vieux Emosson in Valais. Its operation is guaranteed by Nant de Drance SA whose shareholders are Alpiq (39%), SBB (36%), IWB (15%) and FMV (10%)