Emerging opportunities for UK long duration energy storage

2024 marked a turning point: for the first time in history, renewables supplied more than half of the UK’s electricity. Wind and solar made up the lion’s share, driving a 70% fall in power sector emissions since 2010. Coal has all but disappeared, and renewables are now the cheapest source of new power.

But there’s a catch. Renewable energy is plentiful when the wind blows and the sun shines, yet wasted when supply exceeds demand. In 2024 alone, 10% of UK wind power was curtailed, enough to power millions of homes. And when renewables dip, we still fall back on fossil fuels. This is why long-duration energy storage (LDES) is emerging as the missing piece of the UK’s clean energy puzzle.

LDES and the path to Clean Power 2030
The UK has set bold targets: 95% clean power by 2030 and a fully decarbonised grid by 2035. Achieving them requires more than building wind farms and solar parks, it demands flexibility. LDES provides exactly that, storing renewable electricity for hours, days, or even weeks. By cutting waste, reducing costs, and backing up the grid, LDES makes it possible to run on clean power around the clock.

The National Energy System Operator estimates that 11.5–15.3 GW of LDES will be needed to meet decarbonisation goals, a massive step up from today’s 2.8 GW.

From remote hydro to next-generation storage
Almost all of today’s long-duration storage comes from four pumped hydro sites, far from major demand centres. The next wave must be different: deployable near cities, industrial clusters, and grid bottlenecks.

That’s where UK innovators are stepping up:

• Flow batteries – Companies like Invinity Energy Systems are rolling out projects that deliver 8–12 hours of reliable storage with minimal degradation. Its first commercial-scale system will be online by 2026. Innovators such as RFC Power are pushing new chemistries, like hydrogen–manganese, promising higher efficiency at lower cost.
• Air Energy Storage – Highview Power is building the world’s largest liquid air storage plant near Manchester, a 300 MWh facility set to anchor the next phase of clean energy. Meanwhile, Keep Energy Systems is piloting modular compressed air storage that can be deployed at industrial or community scale.
• Thermal Energy Storage (TES) – Going beyond electricity, TES could decarbonise some of the dirtiest industries. By converting surplus renewable electricity into heat stored in molten salts or ceramic blocks, TES can reach temperatures above 1,200°C — enough to clean up steel, cement, and glass production. Companies like Exergy3 are leading the charge.
  
  

Policy momentum and investor appetite
The UK government has recognised the opportunity. Its new cap-and-floor mechanism gives investors revenue certainty while encouraging innovation in both proven and emerging storage technologies. Industry response has been overwhelming, 171 projects were submitted in the first round alone.

The outlook
LDES is still early-stage, but momentum is building fast. With the right mix of technology, policy, and investment, LDES could become the backbone of the UK’s clean energy system, ensuring that by the 2030s Britain runs not just on cheap renewables but on reliable, round-the-clock clean power.