On Wednesday morning, as commuters passed through London’s King’s Cross during another summer heatwave, National Grid engineers monitored the country’s rapidly fluctuating electricity demand. With solar and wind output peaking and dipping on an hourly basis, the UK is turning to long-duration energy storage (LDES) to stabilize the grid and advance its net-zero ambitions.

LDES refers to technologies capable of storing energy for more than four hours and releasing it when needed—crucial for balancing intermittent renewables. Unlike traditional lithium-ion batteries, which typically discharge over a few hours, LDES solutions such as flow batteries and compressed air can sustain output overnight or even for multiple days. The UK Department for Energy Security and Net Zero has identified LDES as a strategic priority, targeting at least 30 GW of low-carbon flexibility—including storage, by 2030.

Industry leaders, including EDF Energy and Highview Power, are piloting new LDES projects across England and Scotland this quarter. Highview’s Manchester plant, for example, uses liquid air technology to store electricity during periods of excess and release it back to the grid when solar and wind generation drops. Early results show the facility can provide up to 50 MW for eight hours, with plans to scale output in the coming months.

However, deployment is not keeping pace with targets set for 2026 and beyond. While over £100 million has been allocated in grants and contracts this year, only a fraction of announced capacity is operational. Policy analysts at the UK Energy Research Centre warn that regulatory uncertainty and slow permitting risk delaying the large-scale rollout needed for reliable clean energy supply during peak demand—such as the current summer surge.

As the UK heads into late August with record temperatures and rising energy use, the delivery of long-duration storage will be tested in real time. Without rapid progress, experts caution that the UK’s 2030 decarbonization goals could be at risk, underscoring the urgency for both public and private sector action.