Certain Energy Raises £10m to Solve the Missing Piece in the Renewable Energy Grid

Renewable energy is becoming cheaper and more widespread, but one major problem remains. The sun does not always shine, the wind does not always blow, and electricity grids need reliable power when renewable generation drops.

UK energy storage startup Certain Energy is tackling that challenge after raising £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.

The company, formerly known as RFC Power, is developing manganese-based flow batteries designed to store renewable electricity for hours to days, providing a potential alternative to conventional lithium-ion systems for longer-duration applications.

Turning excess renewable energy into reliable power

Founded in 2017 as a spin-off from Imperial College London, Certain Energy has developed a flow battery that uses manganese, one of the Earth's more abundant elements.

Its system can increase storage duration by expanding the size of its electrolyte tanks rather than simply adding more battery cells. The company reports round-trip efficiency above 75%, while its patented electrolyte is designed for a 20-year operating life with minimal capacity degradation.

That could become increasingly valuable as renewable generation expands.

According to Certain Energy, the UK spent around £1.5 billion last year paying renewable generators to reduce production during periods of excess supply. The UK's grid operator expects the annual cost of this curtailment could reach £8 billion by 2030 if the problem is not addressed.

Why investors are backing long-duration storage

For founders and investors, Certain Energy's raise highlights a growing opportunity within the clean energy market.

The next challenge for renewables is not simply generating more electricity. It is storing that electricity efficiently and making it available when demand requires it.

Tim von Werne, Chief Executive of Certain Energy, has argued that long-duration storage could become a critical part of a renewables-heavy energy system. The company is now moving from technology development towards commercial deployment.

The new funding will support a grid-connected MWh-class system in India, expand Certain Energy's UK research facility and establish the supply chain needed for repeatable commercial projects. The British Business Bank is investing £3.5 million as part of the round.

For Certain Energy, the opportunity is significant. If its manganese flow battery can deliver reliable long-duration storage at competitive costs, it could become an important piece of the infrastructure needed to make renewable energy more dependable at scale.

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