The UK government has launched a £28 million funding challenge to develop energy storage technologies capable of supplying electricity for at least 100 hours, with a focus on next-generation batteries and underground hydrogen storage.

Announced on 20 August 2026, the Ultra-Long Duration Energy Storage (Ultra-LDES) Challenge will provide grants to UK innovators developing technologies that can store renewable electricity and release it when wind and solar generation is insufficient.

The programme is funded by the government through UK Research and Innovation (UKRI) and forms part of the UK's wider effort to increase the flexibility of its electricity system while reducing its dependence on gas-fired generation.

According to the government, technologies supported through the programme must be capable of delivering clean electricity for 100 hours or more, equivalent to at least four days of continuous supply.

Wind and solar are currently the cheapest forms of electricity generation in the UK, but their variable output means other technologies are required when renewable generation falls. The government expects ultra-long duration storage to allow excess renewable electricity to be stored during periods of high generation and dispatched when the system needs it.

Batteries and underground hydrogen storage

The £28 million programme will concentrate on two main technology areas.

The first will support the development of electrochemical storage technologies capable of supplying electricity for more than 100 hours. These technologies have yet to reach large-scale commercial deployment, according to the government.

As part of this area, UKRI has launched a separate competition providing up to £3 million for project development studies focused on electrochemical ultra-long duration storage. The studies are intended to help bring battery technologies capable of supplying cost-effective electricity to the grid for 100 hours or more closer to commercialisation.

The second area will support the development and testing of underground hydrogen storage systems, which would store hydrogen for extended periods and release it when required by the energy system.

Government estimates indicate that underground hydrogen storage could reduce total UK energy system costs by between £14 billion and £50 billion between 2035 and 2050.

Energy Minister Michael Shanks said the investment would support technologies needed to store domestically generated clean electricity and reduce dependence on gas generation.

“Homegrown clean energy is our route to more affordable bills and energy security and storing it for when we need it most is critical,” Shanks said.

Science Minister Chris McDonald said solving the challenge of storing renewable electricity could improve energy security and contribute to lower energy bills over the longer term.

Jenny Hill, UKRI’s Clean Energy Challenge Director, said developing effective storage technologies would be an important component of the UK's transition towards a cleaner and more secure electricity system, while potentially supporting skilled employment and private investment.

Part of £102 million clean energy programme

The launch completes the rollout of the government's £102 million Clean Energy Challenges programme, which combines the £28 million Ultra-LDES Challenge with the £74 million Consumer-led Flexibility Challenge.

The latter programme focuses on technologies that can shift electricity consumption towards periods when power is cheaper and more readily available, reducing pressure on the electricity system.

Both initiatives sit within the Research and Development Missions Accelerator Programme (R&D MAP), through which the UK government plans to invest at least £500 million by 2030 in research and development.

Projects supported through R&D MAP are also expected to work with industry, academia and the third sector to leverage a further £1.5 billion in private investment by 2030.

The Ultra-LDES announcement comes as UK energy regulator Ofgem is consulting on plans to support 16 long-duration electricity storage projects, including investment that could enable the country's first new pumped-storage hydropower projects in more than 40 years.

The government sees these initiatives as part of a broader strategy to expand domestic clean energy, increase system flexibility and reduce exposure to volatility in international gas markets.