100 years ago, pioneers from Kraftwerke Oberhasli ventured into electrification. In doing so, they created superlative structures – and supplied renewable electricity as far as Basel and Zurich. The whole of Switzerland still benefits from this today.
Electricity from hydropower is one of the renewable energies – and is an important element in achieving the energy transition. Many people today are no longer aware of the pioneering achievements we owe to it. The history of Kraftwerke Oberhasli, KWO for short, in the Bernese Oberland puts everything into perspective. “KWO was founded in 1925 at a time of scarcity. The aim was to move away from coal as an energy source and drive electrification forward,” says Daniel Fischlin, CEO of Kraftwerke Oberhasli.
As early as 7 March 1906, the founding fathers received the concession for their company, Vereinigte Kander- und Hagneckwerke, to use the water power of the Aare and its tributaries from the Grimsel to Innertkirchen. They prevailed over a private investor who wanted to use the energy, among other things, to extract iron ore. The Bern government gave preference to Vereinigte Kander- und Hagneckwerke, which later became Bernische Kraftwerke AG and later still BKW, because it wanted to use hydropower as much as possible in the public interest and prevent speculation.
That is why KWO was founded
For almost 20 years, the pioneers of BKW subsequently examined more than half a dozen project variants for generating electrical energy from hydropower. Their goal: to build the entire infrastructure themselves and finance it by increasing share capital. However, this proved impossible. That is why, on 20 June 1925, they founded Kraftwerke Oberhasli AG, in which the Canton of Bern took a financial stake. The plan also included issuing bonds to interested parties to finance construction.
Although no other partners were involved yet, construction work on the Handeck 1 power plant at Grimsel began in the same year. In the course of this work, not only was the arch-gravity dam built – at 114 metres, then the highest dam in Europe – but also the 42-metre-high dam wall at Seeuferegg. Both structures close off the reservoir of Lake Grimsel. In 1932, everything was completed and made a great impression all round. This also pleased the Canton of Basel-Stadt and the City of Bern, which had each taken a one-sixth stake in KWO in 1928 and 1930 respectively. In 1938, the City of Zurich followed suit.
The first large pumped-storage power plant
In the midst of the Second World War, the second stage was tackled and the Innertkirchen hydropower plant as well as the Handeck 1 power station were built – Europe’s first underground power plant. It was built underground because of the threat of rockfall and air raids, and because no valuable cultivated land was to be built over. Later milestones included, among other things, a dam on Lake Räterichsboden that was embedded into the landscape as optimally as possible, and in the 1970s the first large pumped-storage power plant, with which energy can be stored and released again at peak times. At the beginning of the 2000s, KWO also became the first hydropower company to establish its own ecology department. “KWO has always been at the forefront, and we want to continue nurturing this culture,” says Daniel Fischlin. “Today, for example, we are considering how we could use a robot in power plant maintenance.”
Future plans
Another project that people would currently like to tackle is an additional reservoir with a new power plant at the Trift. Although enshrined in law with the adoption of the new Electricity Act, an environmental organisation had previously fought against it. In the meantime, however, it has shown itself willing to talk and is considering withdrawing its complaint. “The Trift would increase security of supply in winter,” emphasises Daniel Fischlin. The whole of Switzerland benefits from this. This is because KWO supplies its electricity beyond cantonal borders. KWO also provides important services for stabilising the Swiss electricity grid. Its powerful hydropower plants can respond to supply and demand as needed and at the touch of a button. With the additional and non-schedulable energy from renewable sources such as wind and solar, the system services provided by large hydropower plants are becoming increasingly important.
KWO is also continuing to build impressive infrastructure. On 20 June 2025 – exactly 100 years to the day after its foundation – it will inaugurate the new dam wall at Grimsel. This will take place in the presence of Federal Councillor Albert Rösti, Bernese Government Councillor Christine Häsler and Bernese Government Councillor Christoph Ammann. This wall in front of the wall replaces the old dam, which is showing its age. At 113 metres, it is one metre lower, but can be raised if required in order to increase the storage capacity of Lake Grimsel – also a project that KWO would like to realise. The current level is 94 million cubic metres of water.
The anniversary weekend will be celebrated
An anniversary weekend for the general public will take place on 21 and 22 June 2025. The highlight is the walk along the old and new wall. It is sure to be an unforgettable experience.
