The facility adds 480 megawatts of capacity to the existing Kaprun power group, raising turbine capacity by 53% to 1,382 MW and pump capacity by 75% to 1,120 MW. Operated by VERBUND, Limberg III is designed to strengthen Austria’s grid stability and security of supply by delivering flexible energy storage and generation.
VERBUND highlighted the project’s importance in a statement: “Limberg III makes a decisive contribution to maintaining the country’s grid stability and security of supply by providing highly efficient flexibility. The expansion of the ‘Green Battery’ in the heart of Austria is an important building block for the successful energy transformation.”
AFRY, acting as the local site supervision partner for VERBUND Hydro Power GmbH, supported the project with technical and commercial supervision, geological documentation, and natural hazard consulting. The work involved extensive engineering, including tunnelling, cavern construction, a 558-meter pressure shaft, and a machine cavern located 450 meters underground.
“With a total installed capacity of 480 MW and a partial converter, Limberg III is designed to respond flexibly to grid demands, storing and releasing energy during peak periods. It uses existing reservoirs Mooserboden and Wasserfallboden without requiring new surface storage,” AFRY stated.
Ernst Zeller, Head of Hydro at AFRY, praised the project team: “I’m incredibly proud of our team’s dedication and precision throughout this project, from the first geological surveys to the final inspections. Their expertise and commitment have been instrumental in delivering such a complex and forward-looking facility. I also want to sincerely thank our client, VERBUND Hydro Power GmbH, for the trust they placed in AFRY.”
The project required sophisticated engineering, notably the lifting of a 355-tonne rotor into position in May 2025. The rotor was assembled underground over the course of a year, using 80,000 stacked sheets. Each generator unit at Limberg III can operate at variable speed, with a range of 20 to 240 MW in turbine mode and 100 to 240 MW in pumping mode.
VERBUND invested around €572 million in the development. The new plant is expected to play a vital role in balancing supply and demand across Austria’s electricity system, while supporting the broader transition to renewable energy sources. Limberg III demonstrates how advanced hydropower infrastructure can provide reliable storage capacity and grid flexibility without the need for new surface reservoirs.
