A milestone for energy transition: Riedl energy store gets green light

VERBUND subsidiary Donaukraftwerk Jochenstein AG has had its plans approved for the Riedl energy store.

The Riedl energy store’s pumped storage power plant with a flexible power of 300 MW has been in the process of gaining planning approval since 2012. During this period, the European Commission regularly included the project on the list of European priority project interests with regard to the energy transition. On 16th September 2025, Bavarian Prime Minister Markus Söder ceremoniously issued the decision to approve the plan in the presence of Bavarian Minister of Economic Affairs Hubert Aiwanger, Environment Minister Thorsten Glauber and District Councillor Raimund Kneidinger to VERBUND CEO Michael Strugl and the project managers from Donaukraftwerk Jochenstein.

Work will start on aquatic ecological measures surrounding the Riedl energy store on the Austrian side in early October 2025.

VERBUND CEO Michael Strugl stated:

"The ambitious expansion targets for renewables by 2045 are huge in Bavaria and Austria. Rapid expansion of networks and large-scale storage facilities is therefore essential. Here, the Riedl energy store will play an indispensable role in ensuring grid stability and the secure supply of clean electricity in the Bavarian and Austrian regions. This power plant project will increase VERBUND’s investment volume in the Bavarian hydropower to around EUR 1.7 billion by 2030.

Bavarian Minister of Economic Affairs and Energy Hubert Aiwanger

“Storage facilities are as important for the transition to clean energy as expanding photovoltaics and wind power is. So I am all the more pleased that the plans for the Riedl pumped storage power plant have been approved. With a storage capacity of 3.5 million kilowatt hours, Riedl will become a key component of our power system. Today, more than one million PV systems in Bavaria often generate more electricity than is needed at lunchtime. Instead of regulating these systems during peak periods, in the future this surplus may be temporarily stored and then fed back into the grid when electricity demand is high and supply is low. This is more important than ever with a view to the continued construction of more than 700 planned wind turbines. In addition, Riedl will probably save more than 100,000 tons of CO2 annually and strengthen the Bavarian economy. In the future, this electricity will also be supplied to the chemical triangle in particular. I would like to thank all those involved at VERBUND, the Passau district council office, the government of Lower Bavaria and the Ministry of Environment, who have now brought this complex process to a successful conclusion."

At the meeting with the State Chancellery, District Councillor Raimund Kneidinger recalled that the decision marks the end of what has been the most extensive procedure in the history of the office.  He praised the employees involved for being "as diligent as they are unperterbed by the attention that such a controversially debated major project naturally deserves". The objective and fair cooperation of participants on all sides of the process also contributed to this outcome.

The Riedl energy storage project — contributing to the transition to clean energy

The Riedl energy store, the plans for which were submitted for approval by VERBUND’s two-state Donaukraftwerk Jochenstein AG (DKJ), is a highly flexible pumped storage power plant with a power of 300 MW. The efficiency of this technology, which has been tested over the long term, is around 80%. In the event of excess electricity from wind power and photovoltaics, this electricity is used to pump water from the reservoir of the Jochenstein Danube power plant into an upper basin located around 330 metres higher and to temporarily store it there. When demand is high or there are bottlenecks in the grid, water from the reservoir is fed to the underground turbines in mere seconds, which in turn generate electrical energy via generators.

Water for the Riedl energy store is drawn from the Jochenstein reservoir and returned to the Danube. The border between Germany and Austria is located here, in the middle of the river. The two Jochenstein and Aschach reservoirs are used as basins.

A new 24-hectare reservoir with a usable capacity of around four million cubic metres of water will be used as the upper basin. From there, a secure underground tunnel leads to a power station at Jochenstein power plant, which is also underground. This is home to two highly flexible generator sets, each with a power of 150 MW. The electricity generated there is fed into the existing switching station of the Jochenstein Danube power plant. The project will not touch the environmentally valuable Donauleiten, as the structures are located deep below them in the mountain.

A new wildlife migration aid is being built around the Jochenstein Danube power plant to make the Danube River passable again for fish and other aquatic organisms in this section of the river. Once completed, this area will serve as an additional habitat for fishes, offering opportunities to migrate around the power plant, especially as a habitat for spawning and juvenile fish. A number of accompanying environmental measures will also be implemented in the wider vicinity of the power plant and pumped storage.

The two managing directors responsible for Donaukraftwerk Jochenstein at VERBUND Hydropower, Karl Heinz Gruber and Michael Amerer said the following: "The construction and operation of the Riedl energy store will not only be an important building block for the energy transition and security of supply in Bavaria; it will also set in motion a whole chain of economic impulses in the construction industry, the manufacturing industry, and the service sector. More than 30% of the value created by the investment will remain in the region. Around 2,800 additional employment effects will be created during the construction phase, with up to 400 people working on the construction site at peak times. In the long term, the economy and population in Bavaria and Austria alike will benefit from the pumped storage power plant, because the electricity generated is supplied to Bavaria and Austria in equal parts, 50:50.

Work to implement the aquatic environmental measures will start in October 

VERBUND/Donaukraftwerk Jochenstein will start implementing the ecological measures in the Jochenstein reservoir on the Austrian side from October 2025. This involves preparatory ecological work for the Riedl energy store.

A key measure is the restoration of riverbank areas. Many sections of the Danube are restricted by artificial bank defences and building development along its natural course. The creation of new, semi-natural riparian zones will create future habitats for fish, birds, amphibians and other animal species. The river is once again becoming more nature-orientated and valuable floodplains are emerging.

When planning gravel banks and oxbow lakes, particular attention was paid to creating spawning habitats for fish in order to increase the population.

Alois Pröll, Chairman of the Passau-Jochenstein Fishing Association: "Our association, Fischereiberechtigten Passau-Jochenstein e.V., is very optimistic about the planned ecological measures and expressly supports them. The creation of new spawning habitats and landings will bring significant improvements to our waterbody structure. For many years, we have fought in vain with the relevant authorities for the measures that are now being implemented here. Our association’s highest priority is to preserve a liveable river landscape with a balanced fish population in a quantity commensurate with the size of the river. These measures are a big step towards achieving this goal."

The first central step is to restructure and extend the mouth of the Kößlbach. On the adjacent areas of around 6 hectares, an old embankment, several amphibian pools and a new, large gravel island will be built on the banks of the Danube. A total of around 190,000 m³ of material will be moved around this complex.

In addition, the Hecht oxbow lake, which was heavily silted up by flooding, will be freed from fine sediments and lowered. In the area of the Jochenstein Danube power plant, an existing oxbow lake in Roning will be lifted during the first construction phase that is now underway, and the gravel bar will be expanded by the outdoor swimming pool in Engelhartszell.

Key data on the Riedl energy store

• Investment volume: over EUR 400 million
• Generator output: 2 x 150 megawatts
• Reservoir volume: 4.2 million m³
• Upper basin water area: 24 ha
• Average drop height: 331.5 m
• Average Danube outflow: 1,420 m³/s
• Turbine operation flow: 108 m³/s
• Pump operation flow: 83 m³/s
• Power station site: Municipality of Untergriesbach/district of Jochenstein
• Reservoir site: Municipality of Untergriesbach/district of Gottsdorf

VERBUND operates 22 run-of-river power plants with an output of around 1,040 MW in Bavaria and on the Austrian-Bavarian border and generates green electricity from hydropower for 1.8 million households.