Pumped storage has tremendous potential to increase globally and can even be developed in areas where there is limited opportunity to pursue conventional hydropower projects. Although these water batteries, according to the International Hydropower Association (IHA), will prove to be a vital part of future hydropower development, important policy recommendations still need to be considered to ensure the technology is fully utilised in a renewable-dominated energy landscape. In its 2023 World Hydropower Outlook report, IHA says such considerations include:

  • Comprehensive Planning – policymakers must anticipate long-term clean electricity requirements.
  • Site Identification – systematic mapping and assessment of existing and potential sites suitable for pumped storage is necessary to guide sustainable infrastructure development and inform energy policy decisions.
  • Sustainability Assessment – rigorous sustainability evaluations using internationally recognised assessment tools should be integrated into development processes.
  • Financial Frameworks – robust financial policy mechanisms need to incentivise pumped storage developers and enable long-term revenue visibility. Furthermore, electricity markets should reward grid stability contributions provided by pumped storage and allow its inclusion in green finance initiatives.

In the UK, various bodies are calling on the government to provide such a supportive policy framework to encourage investment in pumped storage development. Although a new facility hasn’t been commissioned here since 1984, there are currently six projects being developed which could substantially contribute to the UK government’s power decarbonisation target and security of energy supply by 2035.

Currently under development in Scotland, these six new projects are set to more than double the UK’s capacity for pumped storage hydro to 7.7GW, create almost 15,000 jobs, and generate up to £5.8 billion for the UK economy, according to a new report by Scottish Renewables and BiGGAR Economics.

Entitled ‘The Economic Impact of Pumped Storage Hydro’, the report studied the Cruachan Expansion and Balliemeanoch projects, both in Argyll and Bute, Corrievarkie in Perth and Kinross, Glenmuckloch in Dumfries and Galloway, and Red John and Coire Glas in the Scottish Highlands. If constructed, these projects would add 4.9GW to the UK’s existing capacity of 2.8GW, taking the country over halfway towards achieving the 15GW of capacity that is expected to be needed by 2050, while more than quadrupling its storage capacity to 122GWh.

To ensure that developers can deliver the existing pipeline of ‘shovel-ready’ pumped storage hydro projects, Scottish Renewables (known as the voice of the country’s energy industry) is calling on the UK Government to urgently deliver the measures it has promised to enable investment in large-scale, long-duration energy storage.

“An investment framework is needed to secure the massive capital investment required for these projects,” says Andrew MacNish Porter, Policy Manager for Economics and Markets at Scottish Renewables. “We therefore urgently need the UK Government to clarify its support for pumped storage hydro and deliver the required policy support to unlock the huge value these projects promise to deliver.”

With SSE Renewables saying it stands ready to invest in this vital technology and Drax adding that, with the right support in place, it is ready to invest more than £500 million in expanding the Cruachan plant on the shores of Loch Awe, the government is being pressurised into agreeing to a market investment framework to aid the deployment of projects so the sector can reach its vast potential.

“Pumped storage hydro is the key to unlocking a cleaner, more resilient energy system for the UK, while generating significant economic benefits,” Mark Wilson, CEO of Intelligent Land Investments Group, commented. “With the potential to create over 8000 jobs annually and an estimated investment of up to £21 billion, it’s time for the UK government to take action. By introducing policies that support long-term investment signals, such as ‘cap and floor’, we can unlock the full potential of this technology, enhance energy security, and accelerate our transition to net zero.”

In an open letter to UK Prime Minister Rishi Sunak, First Minister of Scotland Humza Yousaf added his support by saying industry representatives have been clear that for long-duration energy storage solutions to progress they require a cap-and-floor mechanism that ensures a minimum level of revenue.

“With an appropriate market support mechanism, several pumped hydro storage projects across Scotland, that have already secured planning permission, could begin construction immediately and would provide vital resilience and flexibility as thermal generation starts to retire,” Yousaf said, adding that pumped storage is currently the only major renewable electricity technology ineligible for UK Government support, while he is concerned that slow action in this area is dampening investor confidence, preventing projects from coming forward. “UK Government inaction on this issue represents a significant obstacle to deployment, and risks failing to secure the economic benefits of pumped hydro storage projects.”

Yousaf also recently visited the 152MW Sloy Hydropower Station upon SSE Renewables’ announcement that it’s planning to convert the facility into a pumped storage scheme, which could deliver up to 25GWh of long-duration storage capacity and enable the provision of firm and flexible renewable energy for up to 160 continuous hours.

Highlighting the significance of facilities like Sloy, especially during periods when renewable energy generation fluctuates, Yousaf said: “Hydropower was the country’s original source of renewable energy and it has the potential to play a significantly greater role in the transition to net zero – both on a small-scale in co-operation with local communities and on a larger scale, to help to ensure a continued resilient and secure electricity supply.”

SSE Renewables will now refine the project design for converting the Sloy plant into a pumped hydro storage facility, followed by a period of public consultation later this year. Pending a positive consenting outcome and a supportive policy environment, the company aims to make a final investment decision by late 2025 and commissioning of the new pumped storage scheme could be achieved by 2028.

New Developments

In other company news, GE has announced that it will deliver 6x37MW power generating units for the 200MW Chira Soria Pumped Storage Power Plant in Gran Canaria, Spain. The project will use seawater, desalting it before it reaches the upper reservoir, and will play a pivotal role in the island’s energy transition, strengthening the security of supply which is essential for such an isolated electricity system. Chira Soria will also increase renewable energy production on the island by 37%, raising the average annual coverage of demand using renewable generation to 51%, leading to an additional reduction in annual CO2 emissions of 20%. In addition, less dependence on more expensive energy imports is expected to help achieve annual savings in variable generation costs amounting to €122M. Water from the scheme will also be used for agriculture, livestock, firefighting, reforestation and helping to reduce desertification.

GE’s scope of work includes the design, supply, transport, and commissioning of the turbines, generators, main transformers, and electrical balance-of-plant equipment. The project, which has been designed with 91% of infrastructure underground to minimise visual impact, is expected to come online in 2027 with an energy storage capacity of 3.5GWh.

Pascal Radue, GE Hydro Solutions President and CEO, said: “As renewable energy generation from wind and solar is increasing in the Gran Canaria Island, this pumped storage project will help balance the grid by dispatching the energy when needed, still with renewable energy. Hydropower is the largest source of energy storage that exists right now and represents 95% of all energy stored today. Using water from the sea also demonstrates that with ingenuity, hydropower can reach new heights.”

GE Hydro Solutions is also set to replace 4x125MW pumped turbines and generators of the Porabka Zar pumped hydro storage plant in Poland. With an installed capacity of 500MW, Porabka Zar is the country’s second-largest pumped storage power plant and plays a significant role in power generation, providing important ancillary services to the Polish electricity system.

“This rehabilitation project is the first large-scale rehabilitation project of its kind in Poland in 40 years. We are delighted to be part of it and support PGE Odnawialna in this upgrade process,” Radue said. “This demonstrates that Poland makes every effort to achieve the Net Zero goal by 2050. This new equipment will help increase the flexibility and reliability of the plant and consequently stabilize the grid in the country.”

A special feature of this project involves replacing the existing stay rings and vanes with new ones specially designed for Porabka Zar. Due to the confined workspace, the technology used, and the cutting and welding processes will be specific to this project. Commercial operation is expected at the beginning of 2028.


To reduce its dependence on energy imports, Lithuania is aiming to systematically expand its renewable energy sources, especially solar and wind power, and to offset the volatility of these energy sources, Ignitis Gamyba is investing around EUR 150 million in the expansion of the Kruonis pumped storage hydropower facility. Here an additional fifth, highly flexible 110MW pump turbine unit and motor-generator unit will be installed by Voith Hydro and is expected to swing into operation by the end of 2026.

Meanwhile, over in Germany, EnBW Energie Baden-Württemberg is undertaking the conversion and expansion of the 71MW Rudolf Fettweis hydropower plant in the northern Black Forest. Over the next few years, the existing conventional storage power plant will be modernised and turned into the Forbach high-capacity pumped storage power plant. Construction of this €280 million project will start this autumn at the earliest, with completion expected by the end of 2027.

EnBW is focused on the accelerated expansion of renewables and achieving climate neutrality by 2035 and requires additional dispatchable capacity and storage reservoirs that can quickly deliver electricity on demand and ensure stable grid operation.

Following an extensive planning approval process led by the regional authorities in Karlsruhe, this complex project successfully obtained approval on 1 March 2023. As the Mayor of Forbach Robert Stiebler said, hydropower has a long history in the region and securing its future there is a great signal as it embraces the energy transition.

The existing Rudolf Fettweis hydropower plant was built between 1914-26 and comprised the 14Mm3 capacity Schwarzenbach dam and the Forbach and Kirschbaumwasen impoundments. Water is channelled via tunnels and pressure pipes downhill to the Rudolf Fettweis hydropower plant.

At the heart of the new plant, a powerhouse will be integrated into the hillside to accommodate a pump turbine for the Schwarzenbach power plant, capable of generating approximately 54MW in turbine mode and 57MW in pump mode. During construction, the existing Forbach equalisation basin will also be expanded with the addition of a cavern water reservoir in the adjacent hillside which will serve as the lower reservoir.

Over in the US, Dairyland Power Cooperative is collaborating with Mine Storage International and Michigan Technological University to explore the potential for pumped storage hydropower in the Upper Midwest. Dairyland will be evaluating the development of underground pumped hydro at closed mines, an opportunity that supports grid reliability and renewable energy generation while repurposing retired industrial sites innovatively.

“The Mine Storage system brings unique benefits as it essentially recycles an existing but unused site into a flexible, carbon-free power storage system without some of the environmental concerns of traditional battery storage,” says Dairyland President and CEO Brent Ridge.

Australian news

Queensland’s only existing pumped storage facility, the 570MW Wivenhoe project in Australia, is set to be given a major A$17 million overhaul to ensure the ongoing reliability of the 285MW Unit 2. Such planned maintenance work on the two units takes place every five years. Unit 1 at the facility will continue to operate as normal during the works, after its own overhaul in 2021.

Undertaking significant maintenance on one turbine at a time means Wivenhoe can continue to operate throughout the overhaul period, providing reliable low-emission energy to the grid. As Queensland’s only current pumped storage hydroelectric power station, it is described as setting the state up for 70 per cent renewable energy by 2032.

Trevor Turner, Wivenhoe Site’s Manager, explained that the maintenance work requires a highly skilled workforce. “Our team will be required to work across three separate work fronts which predominately include working at heights and in confined spaces to inspect and where needed, repair or refurbish the power station structure which is around 50m below Wivenhoe dam level,” he said. “The team is very proud of the work we are doing to preserve and enhance the efficiency and long-term reliability of the power station, and our sharp focus on health, safety, environment and quality will be the key to a successful overhaul.”

Down in New South Wales, Snowy Hydro’s management team has announced that the Snowy 2.0 project could be delayed by up to two years. Set to be Australia’s largest renewable energy project the scheme will link Tantangara Reservoir with Talbingo Reservoir through 27km of tunnels and a power station with pumping capabilities.

Despite significant progress being made, various factors have contributed to schedule delays and cost increases. These include the mobilisation and resourcing implications of the COVID-19 pandemic; global supply chain disruption and inflation affecting the cost and availability of a skilled workforce, materials, and shipping; design elements requiring more time to complete due to their technically complex nature; and variable site and geological conditions.

“While many other major infrastructure projects have been impacted by the same challenges, Snowy 2.0 continues to make positive progress,” Snowy Hydro CEO Dennis Barnes emphasised, adding that the project is providing significant employment and economic benefits both regionally and domestically.

Indian Guidelines

Recent estimates suggest that India will need at least 18.8GW of pumped storage to support the integration of wind and solar into its grid by 2032, and with an on-river pumped storage potential of 103GW plus many off-river sites, the government is keen to promote development across the country.

To help spearhead this push, the government has released its new guidelines aimed at encouraging investment across the sector. Unveiled by the Ministry of Power the new publication makes recommendations for market and policy development to encourage progress and help boost the country’s energy storage capabilities. Listed in the recommendations is the need to monetise pumped storage’s ancillary services, identify and safely develop exhausted mines for prospective sites, and use of concessional climate finance to support development.

The Ministry of Power believes the guidelines will be an important tool in promoting the development of pumped storage projects across India and are confident they will help to unlock their full potential.

This article first appeared in International Water Power magazine.