Today, Electricité d’Emosson SA celebrates 50 years since entry into service of its hydroelectric complex located in both Switzerland and France. This ingenious facility has generated over 40 billion kilowatt hours of renewable electricity. An official ceremony attended by officials from both countries was held atop the dam to celebrate the anniversary. An open day will also be held to give the public a behind-the-scenes look at one of Switzerland’s largest hydroelectric installations.
The construction of the Emosson dam required the flooding of Barberine dam, built by Swiss Federal Railways in 1920, and shifted the border between France and Switzerland. Such was the scale of the feat required to complete the Emosson facility 50 years ago, after eight years of work. Holding 225 million m3 of water, the Emosson dam secures the second biggest reservoir in Switzerland. Filling it was one of the main challenges at the time. A truly ingenious network of eleven water intakes, three collecting pipes and some 50 km of tunnels supplies the dam with water from both sides of the border. It flows through the turbines at Vallorcine power plant, in France, before going on to La Bâtiaz power plant in Switzerland. Designed to peak in line with demand, these two plants have produced over 40 billion kilowatt hours since 1975. “Emosson is much more than just a dam or a number of kilowatt hours: it’s a symbol of Franco-Swiss cooperation, a model of ingenuity and shared vision,” reveals Laurent Pérotin, Vice President of Electricité d’Emosson SA. In fact, apart from the electricity, which is distributed exclusively by Alpiq, France and Switzerland share the entire Emosson operation, from the water intakes to ownership, not to mention the employees in its workforce. Alpiq and EDF each holds a 50% stake.
A constantly evolving asset
Keeping operations at these plants going after five decades is an ongoing priority for Electricité d’Emosson SA. Several major works have been completed to that end over the years. In 2003, La Bâtiaz power plant in Martigny was equipped with an ultra-modern control room, from where the entire facility can be monitored and controlled. The Emosson dam was fully drained in 2012 to allow inspection of its submerged areas. And in spring 2020 major repair work was carried out on the Esserts reservoir, which straddles the border between France and Switzerland and stores water from Val Ferret before it feeds Vallorcine power plant. One of the current major challenges relates to climate change. Several of Emosson’s water intakes are located under the shrinking Argentière glacier and must be continually adjusted and secured in line with the movements in the ice. Regular upgrades are also implemented at the main facilities in Vallorcine and La Bâtiaz power plants. “Our predecessors demonstrated great ingenuity and took risks to build this facility,” explains Amédée Murisier, Chair of the Board of Directors of Electricité d’Emosson SA. “It is now up to us to take good care of it, but also to be enterprising so we can continue to ensure the supply of electricity for future generations.”
Prospective winter power supply for Switzerland
In addition to maintaining existing installations, Emosson plans to raise the dam by 10 metres. This is one of 16 Swiss national projects to increase winter production of hydroelectric power. It would enable the storage of about 116 million extra kWh for the coldest season. The reservoir is currently replenished more than one-and-a-half times a year and some of the water is therefore used in the summer, when Switzerland already has sufficient energy. Annually, the facility produces 850 million kWh. Detailed technical studies and environmental impact assessments should be finalised at the start of next year and discussions regarding water rights are ongoing with France and Switzerland.
Open day – Saturday, 20 September 2025
To celebrate 50 years of engineering and innovation, Electricité d’Emosson SA is inviting the public to come and visit its hydroelectric power plants on Saturday, 20 September 2025:
- La Bâtiaz, in Martigny, from 9.30am to 5.00pm
- Vallorcine, from 10.00am to 5.00pm
The programme for the day includes visits, team meet-and-greets, entertainment for children and adults, quizzes and food trucks. All the information is available at www.emosson.ch/portes-ouvertes.