Pumped storage |


Pumped storage powers ahead


From underground caverns in Austria to record-speed builds in China and long-duration storage studies in the US, pumped storage hydropower is re-emerging as the backbone of renewable integration. A wave of projects in 2025 shows how engineers are adapting old principles to new system needs


FOR MUCH OF THE past three decades, pumped storage hydropower (PSH) projects developed slowly, with a handful of refurbishments and few new schemes. But recently, the pace of announcements, approvals, and inaugurations has shifted dramatically. The reason is simple: as more wind and solar


enter power systems, operators require flexible, long-duration storage. Grid stability cannot be left solely to lithium-ion batteries, which are suited to short-duration cycling but not multi-hour or multi-day balancing. Pumped storage fills that gap, providing not only storage capacity but also ancillary services: frequency regulation, black- start capability, inertia, and peak-shaving. Globally, PSH represents more than 90% of installed grid-scale storage. Plants built in the 1960s and 1970s are still running reliably today. New projects aim for design lives of 70–100 years, creating infrastructure that will support multiple generations of renewable integration. The resurgence of projects in Europe, Asia, the Middle East, and the Americas demonstrates how countries with very different energy systems are converging on the same solution. For hydropower engineers, this creates opportunities but also challenges: tighter timelines, more complex underground works, and integration with digital optimisation tools.


Europe: engineering beneath the mountains Limberg III, Austria Austria’s Limberg III pumped storage power plant entered service in September 2025 after four years of intensive construction. Located in Kaprun, it adds 480MW to the Kaprun group,


bringing total turbine capacity to 1382MW and pumping capacity to 1120MW. The project makes use of the existing Mooserboden and Wasserfallboden reservoirs, avoiding the need for new surface impoundments. A focus was on underground works:


A 558m vertical pressure shaft was bored through challenging alpine geology. The powerhouse cavern lies 450m below ground level, requiring precision blasting and stabilisation. Installation of a 355-tonne rotor, assembled from 80,000 stacked steel sheets over the course of a year, represented one of the most complex logistical operations in Austrian hydropower history.


Each of the two machine sets is capable of variable-speed operation. In turbine mode, the output range is 20–240MW, while in pumping mode it is 100–240MW. This flexibility allows Limberg III to respond rapidly to load fluctuations, making it a key element of Austria’s “Green Battery” strategy. AFRY provided site supervision, geological services, and hazard consulting. Ernst Zeller, Head of Hydro at AFRY, said: “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.” Andritz Hydro provided two variable-speed motor generators (280 MVA each) for the project.


Riedl, Germany Just across the border, Germany recently approved the 300MW Energiespeicher Riedl after more than a decade of permitting. Located near the Danube power plant Jochenstein, the project has long been identified by the European Commission as strategically important for renewable integration in Bavaria. The long approval timeline reflects Europe’s


ANDRITZ provided two variable-speed motor generators (280 MVA each) for Limberg III


regulatory complexity. Environmental assessments, cross-border water impacts, and public consultations slowed progress since planning began in 2012. For engineers, this underlines the importance of early-stage design that can withstand rigorous ecological and


24 | October 2025 | www.waterpowermagazine.com


community scrutiny. Construction is due to start in October 2025 with ecological measures implemented on both the Austrian and German sides of the border. Once complete, Riedl will provide crucial flexibility for Bavaria, where solar penetration is high and seasonal variability significant.


Pracomune, Italy Not all progress in Europe is new build. In South Tyrol, Alperia Greenpower has contracted ANDRITZ to rehabilitate the Pracomune plant, in operation since the 1960s. The plant operates between the Quaira and Fontana Bianca reservoirs and features a ternary unit – a configuration capable of operating simultaneously in pump and turbine mode to optimise response to grid needs. The rehabilitation will replace the existing Francis turbine with a new 42.5MW unit, upgrade the motor-generator from 43 to 45 MVA, and fully refurbish the 37MW multistage horizontal pump. Automation and control systems will also be modernised. On-site work, scheduled from May 2026


to February 2027, must contend with alpine weather conditions and a tight shutdown window. For engineers, this demonstrates the growing role of refurbishments in extending the value of existing assets, where upgrades can significantly boost performance at lower cost and environmental impact than new builds.


China and India: Scaling at speed China: Shangyi and Meizhou China continues to set the global pace for pumped storage expansion. At Shangyi in Hebei Province, construction


has reached two milestones: closure of the lower reservoir and installation of Unit 1’s 372-tonne rotor. With a planned capacity of 1,400MW, Shangyi will provide frequency regulation, peak shaving, and emergency backup for the Beijing–Tianjin and northern Hebei grids. Civil works included a sediment retention reservoir, weir, flood discharge tunnel, and extensive intake/outlet structures. In Guangdong, the Meizhou pumped


storage project (2,400MW) is notable for its record-setting timelines. The first unit of Phase II entered operation in August 2025, only 18 months after installation began. Phase I was already completed in May 2022. Once fully


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