Ebensee pumped-storage project advances as reservoir dam nears completion

Construction of the pumped-storage power plant in Ebensee, in the Gmunden district, is progressing, with the upper reservoir’s dam expected to be finished next week, ORF reported. Austrian President Alexander Van der Bellen visited the site on Friday to review the work.

The project is the largest in the 134-year history of energy provider Energie AG, which is investing nearly half a billion euros. Its centrepiece is an underground cavern measuring 53 metres long, 26 metres wide and 41 metres high. A machine hall is being built inside, with final concrete work under way and the first large equipment components arriving for installation.

Van der Bellen said he was impressed by the scale of the project and its engineering challenges. He also said expanding renewable energy was necessary as electricity demand rises, including because of artificial intelligence and changes in transport.

The upper reservoir in Rumitzgraben will hold about 1.3 million cubic metres of water, equivalent to around 520 Olympic-sized swimming pools. When electricity is in surplus, water will be pumped from Lake Traunsee up about 500 metres through pressure pipes four metres wide. When power is needed, it will flow back down and drive a turbine. At full capacity, the plant can generate electricity for about 10 hours. Energie AG says it will be able to store solar power for around 280,000 households.

Water ingress following the 2024 floods delayed the original schedule by nearly 10 months. The plant is now due to begin operating at the end of 2028, while the reservoir is expected to be filled for the first time in spring 2028. Energie AG chief executive Leonhard Schitter said costs were expected to remain within the planned budget of nearly half a billion euros.