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New pumped hydro around the world: Tried and tested long-duration storage tech makes comeback


For over 100 years, pumped-storage hydroelectric power (pumped hydro) has supported electricity consumption around the world. The principles of the technology are fairly simple, but ingenious: when electricity demand peaks, water falls from an upper reservoir into a lower reservoir, passing through turbines which generate power. The process is then reversed and water is pumped back up the hill during off-peak times when electricity is cheaper such as at night, or perhaps when there is abundant renewable energy such as solar, to drive the pumping.

Statistics vary a little from source to source, but at least 100GW of pumped hydro is thought to be in operation today and according to the International Hydropower Association (IHA) those plants can store about 9,000GWh of power in total. While lithium-ion dominates new energy storage installations, pumped hydro still represents more than 90% of the world’s storage of electricity for the grid and many of these facilities can enable several hours of low-emissions energy at a time.

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That said, while the marginal economic and environmental costs of pumped hydro plants are relatively low, the development of new pumped hydro plants is greatly restricted by factors including the need for land and the ability to either find appropriate sites with large upper and lower reservoirs or to develop the land to add those bodies of water.

However, with the growing need to decarbonise the electricity system and accommodate higher shares of renewable energy, developers are seeking out opportunities to build new pumped hydro facilities. Here are just a few of the recent projects that has come across — from projects at their earlier stages of development to those that are nearing shovel-ready status.


Regular readers of our sister site PV Tech will have noted that the central Asian state of Uzbekistan has become a hotbed of solar PV development over the past year or so. Government tenders and power purchase agreements (PPAs) have spurred massive projects for the likes of independent power producer (IPP) Total Eren and developer Masdar — which in April also broke ground on Uzbekistan’s first wind power plant.

State-owned hydropower producer and project developer JSC Uzbekhydroenergo (UGE) is also currently considering constructing a 200MW pumped hydro storage project in the Tashkent region of the country. Uzbekhydroenergo held meetings with French state-owned utility giant and power project developer EDF in April about the project, along with consideration of plans to develop floating solar PV systems on reservoirs.

Those discussions for what would be the country’s first pumped storage plant remain at an early stage, with the pair reaching preliminary agreements, ahead of the signing of a more formal Memorandum of Understanding (MoU), but UGE chairman Sanginov Abdugani said dialogue at meetings had been constructive.

“Uzbekistan’s hydropower potential is growing, and we want to work with international, best-in-class partners who can help us achieve an optimal use of Uzbekistan’s natural resources, boost energy efficiency and increase renewable energy’s share in our country’s energy mix,” Abdugani said.

United Arab Emirates

From the first in Uzbekistan to the first for the entire Arabian Gulf region, a 250MW pumped hydro plant is under construction in the Hajar Mountains of the United Arab Emirates (UAE), developed by the Dubai Electricity and Water Authority (DEWA). DEWA has been one of the more proactive Gulf state power companies in moving to adopt renewable energy, with Dubai targeting 75% clean energy in its electricity mix by 2050.

The project is being built at the Hatta dam, about 140km from the city of Dubai and will use about 880 million gallons of water dropped about 300 metres from an upper reservoir being built into the dam’s mountain. Water will be sent back up the hill using solar PV power generated from the massive 1GW Mohammed Bin Rashid Al Maktoum solar park which is also currently under construction.

It’s expected to go into service early in 2024 and technology company Hitachi ABB Power Grids said in late May that it is providing grid connection equipment and systems to ANDRITZ Hydro, the specialist hydroelectricity construction company building the facility. Hitachi ABB will supply AC excitation systems tech based on power converters.

Pumped hydro plants use turbines that can be reversible to act as motors, driving the pumping of water back up to the upper reservoir and Hitachi ABB’s systems will enable those pumps to operate at variable speeds to maximise efficiency. The tech company will also provide gear to connect the plant to DEWA’s 132kV transmission network.


Pumped hydro could provide a vital and significant share of the energy storage the US state of California needs to achieve its aggressive renewable energy targets and help ensure blackouts like that seen in August 2020 are not repeated, according to the developer of a 1,300MW pumped hydro plant with 18 hours of storage at the mountainous site of a former mining facility. The project would repurpose abandoned iron mining pits at the site into reservoirs.

Eagle Crest Energy, a developer planning the Eagle Mountain pumped storage plant in Riverside County filed comments with the California Public Utilities Commission (CPUC) regulatory authority in May. Eagle Crest argued that while the state has recognised it needs long-duration energy storage of several hours to integrate higher shares of wind and solar onto energy networks, California could be “painting itself into a corner” through regulatory processes which largely only consider batteries.

This is because large-scale infrastructure projects like Eagle Mountain which take longer do not appear to be part of state agencies’ procurement process consideration, targeting instead ‘Mid-Term Reliability’ — capacity which can come online within the next year to five years. Eagle Mountain has been in development since 2007 and approved federal approval in 2008, then a Federal Energy Regulatory Commission (FERC) license to operate and construct in 2014. It could be online by 2027, Eagle Crest Energy said and NextEra Energy Resources, one of America’s biggest renewables project companies, has said it is ready to construct Eagle Mountain.

However, although the project became one of the first pumped hydro plants to win FERC’s approval in over 30 years, the chances of Eagle Mountain becoming the US’ 25th such plant in operation currently hang in the balance. Local groups are concerned about the use of groundwater and environmental impact at the site, which is close to California’s Joshua Tree National Park, although Eagle Crest Energy founder Steve Lowe rejected those arguments in a 2020 interview with the Los Angeles Times. The project’s development now hinges on gaining CPUC regulatory approval.


Scotland’s iconic Loch Ness, known for the mythical monster that may or may not live in its 22 square miles of water, looks set to be home to a different kind of large-scale inhabitant.

ILI Group, a developer of energy storage projects including grid-scale lithium-ion batteries as well as pumped hydro, said last week that proposals for a 450MW pumped hydro plant on the shores of Loch Ness have been approved by the Scottish government.

Consent was granted by the government Energy Consents Unit after nearly three years of deliberation, to an application made by ILI Group via infrastructure consultancy Aecom. The project, called Red John, will be worth about £550 million (US$774 million) and would create up to 700 direct and indirect jobs while supporting Scotland’s renewable energy growth.

“The Scottish Government has long been supportive of pumped hydro storage for its role in ensuring resilience in our electricity supplies, and for the tremendous opportunity it provides to unlock the potential of renewable energy and support Scotland’s net zero ambitions,” Scottsh cabinet secretary for net zero, energy and transport Michael Matheson said.

“Scotland is a leader in this field, with excellent hydro-electric power heritage built over the last century and this new scheme at Loch Ness will only add to that. As we add more renewable electricity generation across Scotland, investing in pumped hydro storage will be key to balancing our electricity demand with supply and keeping the system secure, as well as creating high quality, green jobs and enabling a green recovery from the COVID-19 pandemic.”

Matheson said Scotland’s government continues to call on the UK government to “take the urgent action required” to provide investors with revenue certainty and unlock investment in pumped hydro in Scotland, which he said has significant potential.

In a report published in March by industry group Scottish Renewables, the UK’s government was warned that climate change targets cannot be met without deployment of long-duration energy storage capacity, including pumped hydro. Indeed the national government already said in a white paper on energy in December 2020 that long-duration energy storage would be crucial, but did not propose any market mechanisms designed to target this deployment.

Australia reported in late May that Australia’s first new pumped hydro plant in nearly 40 years is set to go ahead, with developer Genex having achieved financial close on the project.

The 250MW / 2,000MWh Kidston Stage 2 facility in Queensland will cost about AU$777 million (US$600 million) in total, including the cost of associated infrastructure to connect the plant to the transmission network and to Australia’s National Electricity Market (NEM).

Construction on that project is set to be completed by 2024. There are at least two other large-scale pumped hydro plant projects in development in the country, Snowy 2.0 — which would increase the capacity of an existing pumped hydro plant to as much as 2GW / 350GWh and Oven Mountain, a 600MW / 7,200MWh project. Both of those are in the state of New South Wales.


Slightly old news now, but worth mentioning is Pinnapuram Pumped Storage Project, a pumped hydro scheme in India for which developer Greenko Group won a government tender which was considered the lowest cost solar-plus-storage project proposal in the world.

Awarded a tariff of US$0.054 per kWh, the project will provide power at peak times in the mornings and evenings. The project, in the state of Andra Pradesh, will combine 2GW of solar PV with 400MW of wind and 1.2GW of pumped hydro energy storage. Japanese financial services group ORIX Corporation invested about US$980 million in Greenko to acquire a 20% stake in the company in September 2020, while consultancy AFRY India signed a contract with the developer to provide design engineering services earlier in the year.

Read this Guest Blog from March 2020, by Kowthamraj VS, — a ‘young professional’ at India’s national innovation agency NITI Aayog at the time he wrote it before moving on to pastures new — for some analysis.

As Kowthamraj VS notes in his blog, pumped hydro depends on finding the right specific site to work, and benefits from having local renewable energy capacity nearby with the right transmission infrastructure. If those criteria can be met, he said, the technology can be very attractive and could be an integral part of India’s renewable energy journey. 

Cover Image: Site for Genex's Kidston pumped hydro plant in Australia, the first new pumped hydro plant in the country since 1984. Image: Genex. 

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