Certain Energy’s Pioneering Breakthrough Manganese Flow Batteries to Bring Ultra-Efficient,
Low-Cost Long Duration Energy Storage to Grids Worldwide
London, Wednesday 26th August — Certain Energy, the British long-duration energy storage company, announces it has received £10m Series A funding for its pioneering manganese flow battery technology. The investment will be used to commercialise Certain Energy’s technology and prepare it for deployment to stabilise grids and provide power during periods of low renewables production.
The funding round, led by the British Business Bank with participation from Centrica plc (“Centrica”), Ceres Power Holdings plc (“Ceres”) and Temasek Trust’s Catalytic Capital for Climate and Health (“C3H”), will support Certain Energy as it scales its technology for volume production. This will include the development of a grid-connected MWh-class system in India, expansion of its research facility in the UK, and the creation of the supply chain needed to deliver replicable projects.
“The renewable power market is held back by its vulnerability to external factors,” said Executive Chair, Mark Selby. “Last year, the UK Government spent around £1.5 billion asking renewable energy providers to shut off their operations during peak production, and left unaddressed, the grid operator expects that to climb towards £8 billion a year by 2030. The answer is long duration energy storage and Certain Energy has the technology and now the funding to deliver highly efficient, affordable batteries, based on abundant materials, to make this a reality.”
Michael Shanks, Minister of State in the Department for Energy Security and Net Zero, 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 investing £3.5 million in Certain Energy, the British Business Bank is backing British innovation and helping develop the long-duration energy storage we need to store clean power for days, not hours, and deliver a more secure energy system.”
Previously known as RFC Power, Certain Energy is a British champion in long-duration energy storage (LDES). Founded in 2017 as a spin-off from Imperial College, Certain Energy was created to build battery stores to harvest clean energy and use it to stabilise grids and turn variable renewables into firm green power when required, helping the grid waste less energy and rely less on gas peaker plants.
Certain Energy’s flow batteries are built on manganese, the twelfth most abundant element in the Earth’s crust. Unlike conventional batteries, the system can extend discharge duration by simply increasing the size of its electrolyte tanks, enabling storage from hours to days.
With round-trip efficiency above 75%, the technology is able to compete economically with lithium-ion batteries on key grid services, while also supporting the resilience and reserve functions needed by an increasingly renewables-heavy grid.
Its patented electrolyte is designed for a 20-year operating life with minimal capacity degradation, while its design and materials have the potential to reduce marginal storage costs to around one-tenth of comparable vanadium flow batteries and much cheaper lithium-ion energy storage systems.
Chief Executive Officer Tim von Werne said "Long-duration storage is the missing piece of the clean energy system, and manganese flow is the technology that should win. With the British Business Bank behind us, we have the capital and the mandate to build a global champion here, turning world-class UK science into the industry the energy transition needs."
About Certain Energy
Certain Energy (formerly RFC Power) is a UK long-duration energy storage company developing a manganese-based flow battery designed to deliver affordable, reliable energy storage from hours to days to weeks. Founded on research from Imperial College London, it is building a digital-first engineering capability to design, test and scale at pace.
About the British Business Bank
The British Business Bank is the UK government’s economic development bank. Established in November 2014, its mission is to drive economic growth by helping smaller businesses get the finance they need to start, scale and stay in the UK. Its remit is to design, deliver and efficiently manage UK-wide smaller business access to finance programmes for the UK government.
In 2025/261, the Bank supported UK smaller businesses to access £9.4bn of finance, made up of £1.3bn of public funding, £4.3bn of private capital crowded in by the Bank and £3.7bn of lending the Bank guaranteed. The funding benefited 38,000 UK businesses, including around 30,000 businesses the Bank had not previously helped to fund.
British Business Bank plc is a public limited company registered in England and Wales, registration number 08616013, registered office at Steel City House, West Street, Sheffield, S1 2GQ. It is a development bank wholly owned by HM Government. British Business Bank plc and its subsidiaries are not banking institutions and do not operate as such. With the exception of BBB Investment Services Limited they are not authorised or regulated by the Prudential Regulation Authority or the Financial Conduct Authority. BBB Investment Services Limited is authorised and regulated by the Financial Conduct Authority. A complete legal structure chart for the group can be found at www.british-business-bank.co.uk.
The Patient Capital Funds programme is operated by British Patient Capital Limited, a wholly owned commercial subsidiary of British Business Bank plc.
British Patient Capital Limited is registered in England and Wales with company number 11271076, and registered office at Steel City House, West Street, Sheffield, S1 2GQ. British Patient Capital makes commitments and invests on its own behalf and on behalf of third-party investors whose investments British Patient Capital manages.
1 Figures as at end March 2026
About Ceres Power Holdings plc.
Ceres is a leading developer of clean energy technology: fuel cells for power generation and electrolysers to green hydrogen. Its asset-light, licensing model has seen it establish partnerships with some of the world's largest companies, such as Doosan, Delta, Denso, Shell, Weichai, and Thermax. Ceres' solid oxide technology supports greater electrification of our energy systems, including AI data centres, commercial and industrial applications, and produces green hydrogen at high efficiencies as a route to decarbonise emissions-intensive industries such as ammonia, steelmaking, and electrofuels. Ceres is listed on the London Stock Exchange ("LSE") (LSE: CWR) and is classified by the LSE Green Economy Mark, which recognises listed companies that derive more than 50% of their activity from the green economy. Read more on our website follow us on LinkedIn.
About Centrica
Centrica is a leading integrated energy company focused on meeting the evolving energy needs of households, businesses and governments. Through its portfolio of energy supply, services and infrastructure assets, Centrica plays a critical role in energy security and the transition to a lower-carbon energy system, investing to deliver resilient and affordable energy solutions for the future.
About Catalytic Capital for Climate and Health (C3H)
C3H is a catalytic vehicle by Temasek Trust that provides capital to innovative, early-stage companies in Climate, Health, and their intersection. C3H focuses on companies that deliver tangible impact through bold, scalable solutions. Its activities are anchored by Temasek Trust’s impact areas of Planet, People, Peace, and Progress.
For C3H Alyson Tay (alysontay@temasektrust.org.sg)
Charlotte Lawrence, Managing Director and Head of Direct Equity at the British Business Bank, said, “Faced with recent energy shocks, the UK needs to find ways to improve its energy efficiency and grid resilience. Certain Energy’s technology has proved it can deliver longer duration storage while reducing costs, with potential applications not only in the UK, but across the globe. Our investment will help Certain Energy commercialise and take the next steps towards deployment.”
Rob Booker, Chief Strategy and Transformation Officer, Centrica, explained its involvement in the Series A funding, stating: “Long duration storage is critical to managing the energy system of the future, and Certain Energy’s technology is exactly the kind of innovation needed to reduce costs and improve efficiency, while supporting a more renewables-led, intermittent power mix.”
Stuart Paynter, CFO, Ceres, commented: “Certain Energy has a combination that is rare in this sector: a low-cost, abundant chemistry and a credible, capital-efficient route to manufacturing. We’re glad to back a fellow UK innovator with global ambitions.”
Ryan Tan, Head, C3H, added: “As renewable energy deployment accelerates, the ability to deliver reliable, affordable clean power over longer durations will be critical. Certain Energy’s novel battery technology replaces traditional battery elements with earth-abundant materials such as manganese to deliver cost-effective and scalable long-duration storage performance with less environmental impact. This aligns with C3H’s focus on advancing promising climate innovations, and we see strong potential for Certain Energy’s technology to scale widely for meaningful impact.”
