Ofgem Finalizes 16 LDES Projects as Zenobe Legal Challenge Fails
Britain's regulator has cemented its long-duration storage shortlist after Zenobe's court challenge collapsed, clearing the way for more than 3.8GW of pumped hydro development.
Zenobe's legal challenge to Ofgem's long-duration electricity storage selection process failed on June 30 (2026-06-30), confirming 16 projects as candidates for regulated revenue support and removing the last procedural barrier before developers can advance toward financing.5
Ofgem had trimmed the field from 77 applicants to 16 under a "minded-to" decision published on June 26 (2026-06-26). The cap and floor mechanism sets a revenue floor if power prices fall and a ceiling to contain consumer costs if they surge, giving investors the certainty needed to finance assets capable of storing power over hours or days rather than the minutes delivered by most lithium-ion battery systems.4
Three pumped storage hydro schemes in the Scottish Highlands dominate the list by capacity. Gilkes Energy's 1.8GW Earba project is the largest, followed by SSE's 1.4GW Coire Glas and Statera's 660MW Loch Kemp. One compressed air energy storage project also made the cut. The three PSH schemes alone represent more than 3.8GW of potential new dispatchable capacity.4
Earba is already mobilizing. Gilkes confirmed on June 30 (2026-06-30) that drilling rigs had arrived at the development site the previous month as ground investigation works continued, with the company saying Ofgem's decision had given significant confidence to the supply chain in the project's long-term viability.5
A nationwide blackout in early August cut power to around 1.1 million customers after a lightning strike and two subsequent failures at large-scale power plants. National Grid Electricity System Operator drew on approximately 475MW of operational battery storage to restore grid frequency to normal levels within four minutes of the event.1
But NGESO's final technical report on the incident, published in the week of May 18 (2026-05-18), questioned whether existing reserve levels are sufficient. UK power sector estimates for procuring additional reserve capacity range from £50 million to £250 million per year, leaving the cost question unresolved ahead of any regulatory decision.1
Short-duration batteries have been setting prices more often than many anticipated. In the first quarter of 2026, they set prices nearly a third of the time, driving a 12% reduction in average wholesale electricity costs, according to PV Magazine analysis. Pumped storage and compressed air address a different problem — delivering sustained output over extended periods when wind and solar generation drops, not smoothing intraday volatility.2
Aurora Energy Research calculated that in 2024, around 72 TWh of mostly renewable electricity was curtailed across Europe because of grid bottlenecks, at a cost of roughly €8.9 billion. The European Commission's Joint Research Centre has projected that figure could reach 310 TWh annually by 2040 without sufficient grid investment, equivalent to half the EU's 2022 wind and solar output. The cap and floor framework rests on the assumption that revenue certainty now reduces a larger curtailment bill later.3
With the Zenobe challenge dismissed, the 16 shortlisted developers can advance to detailed design and project finance. Coire Glas, Earba and Loch Kemp together need capital commitments well beyond anything the UK storage market has previously underwritten, and the floor level Ofgem eventually publishes will set the terms on which those financing rounds can close.4,5