Certain Energy, a long-duration energy storage startup, has raised £10 million in Series A funding led by the British Business Bank, with participation from Centrica, Ceres Power Holdings and Temasek Trust's Catalytic Capital for Climate and Health. Formerly known as RFC Power, the Imperial College spin-out builds flow batteries that store clean power and release it when renewable generation falls.
Its 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. Round-trip efficiency sits above 75%, allowing the technology 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. The patented electrolyte is designed for a 20-year operating life with minimal capacity degradation, and the design and materials have the potential to reduce marginal storage costs to around one-tenth of comparable vanadium flow batteries.
Last year the UK Government spent around £1.5 billion asking renewable energy providers to shut off their operations during peak production, and the grid operator expects that figure to climb towards £8 billion a year by 2030. Storage of this kind is intended to turn variable renewables into firm green power, helping the grid waste less energy and rely less on gas peaker plants.
Founded in 2017 as a spin-off from Imperial College, Certain Energy is building a digital-first engineering capability to design, test and scale at pace.
The funding will be used to commercialise the technology and prepare it for deployment, including the development of a grid-connected MWh-class system in India, expansion of the research facility in the United Kingdom, 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. 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.
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.
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.
