The UK’s Energy Gap

By Lawson Steele, CEO, Haldane Energy

Long-duration energy storage (LDES) doesn’t tend to grab headlines, but the dilemma of how the UK will store vast amounts of renewable power to ensure a resilient, robust electricity network is very real. In other words, it’s about keeping the lights on.

In 2023, the Royal Society - Britain’s leading scientific body - warned the UK’s need for LDES had been seriously underestimated. The report concluded LDES is an essential part of the equation to weather prolonged periods of low wind and sunshine.

The report stated that converting renewable power into hydrogen and storing it in salt caverns is one of the lowest-cost options for long-duration storage. Yet more than two years later, the obvious question is: what progress has been made, and what’s missing?

Last month, the Transition Finance Council argued that LDES, including H₂-LDES, should be treated as core national infrastructure. It can help balance intermittent wind and solar, reduce reliance on gas, and lower system-wide emissions.

The good news is that the UK Government is backing the expansion of LDES through its “cap and floor” investment scheme. This is designed to support technologies such as pumped hydro and grid-scale batteries that can store electricity for eight hours or more.

The challenge is this: the energy transition has exposed a new vulnerability. We simply cannot yet store electricity long enough to ride out extended lulls in wind and solar power. As electrification grows, the system will be under increasing pressure.

A quick explainer: why gas still matters 

Understandably, the UK’s current strategy prioritises security of supply. At present, the emphasis is on the age of the nation’s gas power plants and the possibility of extending the lifespan of these assets.

While around 20GW of existing large gas plants (>100 MW) could still be operating in 2035, government and NESO scenarios indicate the system will need at least 35GW of dispatchable capacity. This means that life-extending Britain’s existing gas power stations will only partially meet the UK’s need for flexible, dispatchable power in the mid-2030s.

Carbon capture and storage (CCS) and hydrogen retrofits are also in the mix. However, they are expensive, slow, site-constrained and policy-dependent, so they cannot fully bridge the gap.

At Haldane Energy, we believe hydrogen-derived long duration electricity storage (H₂-LDES) is the missing part of the puzzle.

By using surplus renewable electricity to make hydrogen, storing it underground in salt caverns, and using it to generate power on demand, the projects aim to deliver grid-scale resilience for up to 19 days of supply per site. That enables energy security measured in days, not hours.

As dependence on renewable energy grows, it’s crucial we don’t lose sight of this: life extension of ageing gas plants is a stopgap, not a long-term solution. Put another way, life extension delays the problem. H₂-LDES solves it.