Certain Energy, formerly known as RFC Power, has raised €11.6 million (£10 million) in Series A funding to commercialise its manganese flow battery technology, a long duration storage bet that matters for a grid where the UK government spent around £1.5 billion last year paying renewable generators to switch off, a cost the grid operator expects to reach £8 billion annually by 2030 if left unaddressed. The round was led by the British Business Bank, which invested €4 million (£3.5 million), with participation from Centrica Energy, Ceres Power Holdings and Temasek Trust's Catalytic Capital for Climate and Health.

Certain Energy is a London-headquartered long duration energy storage developer, founded in 2017 as a spinout from Imperial College London, developing manganese flow batteries designed to store renewable electricity for hours to days with an operating life of around 20 years.

Executive chair Mark Selby said: "The renewable power market is held back by its vulnerability to external factors... 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."

Independent grid data supports the scale of the problem Certain Energy is targeting: NESO's own balancing cost projections put constraint payments at £4 billion to £8 billion annually by 2030, up from around £1.7 billion today, a range that broadly matches the figure cited by Selby.

The round is one of at least seven comparable long duration storage and grid-flexibility raises across Europe in 2026 totalling over €167 million, including Amsterdam-based Ore Energy's iron-air battery round and two other UK entrants, Exergy3 and Gaussion, indicating investors are backing multiple competing storage chemistries rather than converging on a single winning technology.

The British Business Bank's lead role continues a pattern of the state-owned lender anchoring early-stage UK deep tech and energy rounds, using public capital to de-risk technologies still years from proven commercial deployment rather than waiting for private investors to validate them first.

For the sector, manganese flow batteries entering a crowded long duration storage field alongside iron-air, thermal and other chemistries suggests the technology choice for multi-day storage remains genuinely open, leaving developers and grid operators with a wider menu of options, and more technology risk, than the lithium-ion market they are used to.

Source: EU-Startups / Business Energy Deals