The UK has provisionally selected three major pumped storage hydro schemes as part of its first long-duration electricity storage (LDES) support mechanism, in a move the industry described as a watershed moment for the country’s clean energy transition.
Energy regulator Ofgem said it was minded to back 16 projects with a combined 7.6GW of capacity under the new cap-and-floor regime, which guarantees developers a minimum income while limiting upside returns. The projects are intended to strengthen energy security and reduce costs in an electricity system increasingly dominated by intermittent wind and solar generation.
The portfolio includes almost 4GW of pumped storage hydro (PSH) capacity – 3900MW in total – alongside compressed air storage and a series of long-duration battery projects.
The three pumped storage projects selected were:
- Earba PSH, a proposed 1,800MW scheme in Scotland;
- Coire Glas, the 1,440MW Highlands project being developed by SSE Renewables; and
- Loch Kemp Storage, a 660MW project near Inverness.
Together, the three projects would provide approximately 87GWh of electricity storage capacity, around three times the UK’s existing pumped storage capability.
SSE said it would now assess the outcome of the LDES project assessment for Coire Glas and engage with Ofgem on a number of detailed issues that will need to be resolved before the project can proceed.
The company described Coire Glas as one of the UK’s most advanced pumped storage hydro projects and said its delivery would support a cleaner, more secure and more affordable energy system.
SSE said that any final decision to progress Coire Glas would be taken in line with the company’s continued focus on capital discipline and with strict adherence to its return thresholds.
Gilkes Energy welcomed Earba’s inclusion on Ofgem’s list, describing the provisional cap-and-floor award as another major milestone for the project.
The company said the list identified projects considered economically viable, deliverable and value for money, with Earba’s inclusion highlighting its strategic importance in strengthening UK energy security and supporting the transition to a low-carbon electricity system.
The announcement follows the arrival of drilling rigs at the site last month as part of the project’s ongoing ground investigation programme.
Located in the Scottish Highlands, Earba is expected to become the UK’s largest pumped storage hydro scheme, with an installed capacity of 1,800MW and 40,000MWh of storage capacity. The project would be capable of delivering more than 22 hours of continuous electricity generation at full output, helping to strengthen grid resilience, improve energy security and balance increasing volumes of intermittent renewable energy across the UK network.
Gilkes Energy said Earba would reduce renewable curtailment costs, increase system flexibility and support a more reliable and secure electricity system by storing surplus renewable energy and supplying it back to the grid during periods of peak demand.
Kate Gilmartin, chief executive of the British Hydropower Association, described the announcement as “a major milestone for pumped storage hydropower” and said the projects would provide the flexibility required to underpin a renewable electricity system.
She said the 87GWh figure was the critical measure, highlighting the ability of pumped storage to deliver power over extended periods rather than simply providing short bursts of electricity to the grid.
Gilmartin said the decisions reflected years of collaboration between industry, government, Ofgem and the National Energy System Operator to create investment conditions for infrastructure that would become “the backbone of our future energy system”.
Unlike batteries, pumped storage schemes can operate for more than a century once built, she noted, making them assets that would serve future generations while improving energy security and system resilience.
The projects are also expected to support thousands of skilled jobs, strengthen domestic engineering and construction supply chains and bring investment to rural and remote communities where many hydro schemes are located.
However, Gilmartin warned that the first allocation round must not be the end of government support for the sector.
Two pumped storage projects failed to secure backing in the initial window, underlining the importance of ensuring that a second allocation round is sufficiently attractive to investors, she said.
“If we are serious about delivering Clean Power 2030 and building a resilient electricity system beyond it, we will need the full pipeline of projects ready to move forward,” she said.
Ofgem said its selected portfolio was designed to provide a mix of technologies, durations and geographic locations, while allowing for the possibility that some projects might not ultimately proceed to construction.
The regulator expects final awards to be confirmed in autumn following consultation on the minded-to decisions.
The wider portfolio also includes the 50MW TeesCAES compressed air energy storage project and a number of lithium-ion battery developments across Scotland, England and the Midlands.
Britain’s Labour government has argued that expanding domestic clean energy infrastructure and storage capacity will help shield consumers from volatile fossil fuel prices, an issue highlighted by recent geopolitical tensions and disruption in global energy markets.
For the pumped storage sector, the decision represents the strongest signal of government support for new large-scale hydro storage projects in decades — but developers argue further rounds will be required if Britain is to unlock its full pipeline of schemes and deliver a fully resilient net-zero electricity system.
