Grand Dixence SA officially unveiled their upgraded Fionnay and Nendaz power stations and the rejuvenated penstock connecting the Lac des Dix reservoir to the Rhone plain. With a legacy spanning nearly six decades, Grand Dixence has been a stalwart in Switzerland’s power generation landscape. Over six years, the complex underwent a comprehensive renovation project, made possible by an impressive CHF 240 million investment from Grand Dixence SA and its partners.
Michael Wider, Chairman of the Board of Directors of Grand Dixence SA, emphasized the project’s significance, stating, “As stewards of the nation’s electricity supply infrastructure, it was our duty to preserve the legacy passed down by our predecessors.”
The Restoration Initiative
The initiative commenced with a thorough analysis of the downhill conduit’s various components, identifying essential renewal, repair, and restoration work. This phase was divided into 89 distinct sub-projects carried out between 2016 and 2023. Beat Imboden, Director of Grand Dixence SA, stressed the importance of these endeavors, noting, “Through our extensive measures, Grand Dixence continues to fulfill its pivotal role by injecting power into the electricity grid swiftly, maintaining the critical balance between supply and demand.”
Each of the six generating units at Grand Dixence’s Fionnay and Nendaz power stations received a comprehensive overhaul. This encompassed the installation of new valves, turbines, alternators, automatic control systems, and auxiliary services. Managing multiple sub-projects concurrently required precise planning and innovative solutions to meet ambitious deadlines. Work continued even as the facilities were gradually reintroduced into service, well before the project’s completion.
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Resuming Operations
From the beginning of 2023, the generating units were methodically brought back into operation to contribute to Switzerland’s electricity supply, particularly during the crucial winter period. Both power stations are expected to return to full operation by the end of the 2023-2024 winter season.
The penstock, connecting Lac des Dix to the Rhone via the Fionnay and Nendaz power stations, also underwent a comprehensive overhaul. The overhead section of the penstock, covering an 850-meter stretch between Péroua and Condémines, was entirely replaced, and the underground sections received renewed anti-corrosion protection. Furthermore, the seven primary valves along the downhill line were refurbished. The safety valves at Louvie and Péroua, located at the start of the penstocks, were replaced, and extensive renovation work was carried out on the valves at the entry points of the water supply galleries at the Grande Dixence dam and the Fionnay reservoir. Managing the disassembly, installation, and logistics of these sizable three-meter-diameter valves posed significant challenges, amplified by their remote, high-altitude locations.
The entire downhill line was reopened in early September 2022, facilitating water supply to the generating plants.
Contributing to Switzerland’s Electricity Supply
An exceptional feature of the Grande Dixence hydroelectric complex is its secondary conduit linking Lac des Dix to the Rhone lowlands. This conduit directs water to the Bieudron power station, Switzerland’s most potent hydroelectric facility with a remarkable 1,200 MW capacity. Notably, during the renovation process, all the water stored in the Grand Dixence dam remained available for harnessing, powering the Bieudron plant.
After six years of dedicated work, Grand Dixence reported the successful return to service of the 290 MW Fionnay and 390 MW Nendaz hydropower stations, along with the penstock linking Lac des Dix to the Rhone plain.
The two power stations forming the Grande Dixence Hydroelectric Complex scheme, initially constructed in the 1960s, have undergone a comprehensive renovation and are positioned to make a significant contribution to Switzerland’s electricity supply security in the coming decades.
Grand Dixence SA and its partners invested CHF 240 million (US$268.7 million) to execute this major project. Michael Wider, Chairman of the Board of Directors of Grand Dixence SA, asserted, “To ensure our facilities continue to play their part in securing the country’s electricity supply in the coming decades, it was our duty to invest in preserving the power generation facilities bequeathed to us by our predecessors.”
The rigorous assessment of the downhill line components and the subsequent execution of renovation and retrofit work demonstrate Grand Dixence SA’s commitment to its pivotal role in Switzerland’s electricity supply and its dedication to maintaining the equilibrium between supply and demand.
