The UK Government has launched the £28m Ultra-Long Duration Energy Storage (Ultra-LDES) Challenge, backed by UK Research and Innovation (UKRI), to accelerate the development of technologies capable of storing electricity for at least 100 hours.
The programme will support projects spanning advanced battery technologies and underground hydrogen storage, with funding aimed at UK innovators developing systems that can hold clean electricity for four days or more before releasing it to the grid.
UKRI has also opened a separate competition offering up to £3m for feasibility studies into electrochemical Ultra-LDES technologies, helping promising concepts move closer to commercial deployment.
The result could be a more flexible and resilient electricity system, with greater capacity to store surplus renewable power and use it when wind and solar generation falls.
By reducing the need to turn to gas-fired generation during periods of low renewable output, the programme could strengthen UK energy security, limit exposure to volatile fuel prices and support the transition to a low-carbon grid.
Speaking on the investment, Minister Michael Shanks said: “Homegrown clean energy is our route to more affordable bills and energy security and storing it for when we need it most is critical.
“By backing new cutting-edge battery technology and hydrogen storage with this £28m grant, we will store more clean power, reduce reliance on expensive gas generation and deliver a more secure energy system.”
Energy storage and UK energy security
Energy storage is becoming increasingly important to the UK’s energy security because the country is seeking to reduce its dependence on imported and internationally traded fossil fuels.
Gas-fired generation is expected to remain part of the energy system for years, particularly when renewable generation is low. However, greater storage capacity could reduce how frequently the grid needs to rely on gas to meet peaks in demand or compensate for periods of weak renewable output.
That matters because international fuel markets can be affected by geopolitical tensions, supply disruptions and changes in global demand.
Storing more domestically generated electricity provides the UK with another way to manage these risks while making better use of homegrown renewable resources.
Why ultra-long duration energy storage is critical to the UK grid
Wind and solar are now among the UK’s most cost-effective sources of electricity, but their output depends on weather conditions. A prolonged period of weak winds or limited sunlight can therefore create a gap between renewable generation and demand.
Short-duration batteries can help balance the grid over minutes or hours, but the UK’s transition to a predominantly renewable electricity system will require technologies that can cover much longer periods.
This is where ultra-long duration energy storage becomes important. Systems that can discharge electricity for 100 hours or more could capture renewable electricity when generation is high and retain it until the grid needs additional supply.
Two technologies at the centre of the challenge
The Ultra-LDES Challenge will focus on two areas that could address this longer-duration requirement.
The first is advanced electrochemical storage. Researchers and companies will develop battery technologies capable of operating for more than 100 hours.
Many of these technologies have yet to reach commercial scale, giving UK developers an opportunity to establish an early position in an emerging global market.
The second area is underground hydrogen storage. The approach involves storing hydrogen and subsequently converting it back into usable energy when required.
According to the programme’s estimates, deploying underground hydrogen storage at scale could reduce total energy system costs by between £14bn and £50bn between 2035 and 2050.
Clare Jackson, CEO of Hydrogen UK, added: “Ultra-long duration energy storage is critical for ensuring the UK moves to a more secure, low-carbon energy system with lower costs for consumers and businesses.
“Hydrogen has a fundamental role to play in that future energy mix, providing a way to store renewable energy over long periods and use it when the system needs it most. Supporting the development of hydrogen storage alongside flexible power generation will be key to unlocking these benefits across the wider energy system.
“The Ultra-LDES Challenge is an important step towards developing the technologies and infrastructure the UK will need at scale, and we look forward to supporting the innovative hydrogen technologies that emerge.”
Building a more flexible electricity system
The Ultra-LDES Challenge forms part of UKRI’s wider £102m Clean Energy Challenges, alongside the £74m Consumer-led Flexibility Challenge. Together, the programmes are designed to develop technologies that can make the electricity system more responsive and efficient.
The investment sits within the R&D Missions Accelerator Programme, which aims to invest at least £500m in research and development by 2030 to address major societal and economic challenges.
The announcement also comes as Ofgem consults on proposals supporting 16 long-duration electricity storage projects. These include plans that could unlock investment in new pumped-storage hydropower, with the UK potentially seeing its first new projects of this type in more than four decades.
As renewable generation expands, the ability to store electricity for days rather than hours will become increasingly significant. The development of commercially viable ultra-long duration energy storage could therefore play a central role in creating a more secure, flexible and affordable UK energy system.
