InvestNot yet confirmed elsewhere1 publisher3 min readPublished
A £10M battery round priced off a curtailment bill nobody has agreed the size of
Certain Energy's Series A rests on a UK constraint-payment forecast of £8bn a year by 2030. The two curtailment figures in the same account differ by a factor of three.
The Investor · Invest desk
What happened
- Certain Energy, the former RFC Power, closed a £10 million Series A led by the British Business Bank, with Centrica, Ceres Power Holdings and Temasek Trust's Catalytic Capital joining.
- The pitch is keyed to UK curtailment payments reported at around £1.5 billion last year and forecast to reach £8 billion a year by 2030.
- The manganese flow chemistry has not been demonstrated at grid scale.
Why it matters
- contradiction A daily rate that annualises to about £548 million and an annual figure of £1.5 billion cannot both describe the same bill, and the choice between them changes the implied growth rate the storage...
- constraint At under one per cent of Form Energy's cumulative raise in nominal terms, this round cannot buy down the grid-scale demonstration risk that separates the two companies, so the next raise is the...
- exposure Anyone putting money in is funding a business that owes a royalty to its largest minority holder and relies on that holder for engineering, which narrows the room to renegotiate later.
- decision State-backed capital sold on domestic energy security is partly financing a first grid project abroad, which forces a question about where UK-funded learning lands.
The two curtailment numbers in the Tech Funding News account do not reconcile. Paying wind and solar farms £1.5 million a day to turn down [20] annualises to about £548 million [14]. The same piece says the UK paid renewable producers around £1.5 billion last year for the same thing [19]. That is a threefold gap inside one article, and it is not cosmetic, because the £8 billion by 2030 forecast [19] is the entire load-bearing number in the investment case.
Start from £1.5 billion and the path to £8 billion is roughly 40 per cent compounding a year [15]. Start from £548 million and it is closer to 71 per cent [c9b]. The first is a fast-growing liability. The second is a forecast doing work that the current run rate does not support. An investor buying long-duration storage on constraint revenue needs to know which curve they are underwriting, and the published material does not say.
Then there is the mismatch in scale. The global long-duration energy storage market was worth $3.6 billion in 2025 and is forecast at $9.5 billion by 2035, a 10.5 per cent compound rate [21]. Britain alone is projected to be wasting £8 billion a year five years before that [19]. Currency conversion aside, the problem is being sized larger than the industry expected to absorb it, and the industry is forecast to grow at a quarter of the rate the problem is.
Certain Energy is bringing £10 million to that, of which the British Business Bank supplied £3.5 million, or 35 per cent [2][3][18]. Form Energy has raised more than $1.2 billion and holds commercial contracts [6]; Certain has not yet shown its technology works at grid scale [1]. In nominal terms, before any FX adjustment, this round is under one per cent of what the incumbent comparator has drawn down [17]. The manganese chemistry may well be cheaper than vanadium by the tenfold margin claimed [8][24], and decoupling duration from cell count by enlarging electrolyte tanks [9] is a real cost lever. Neither is verifiable below grid scale, and £10 million does not reach grid scale.
The cap table adds a second charge on that money. Ceres Power took full ownership in September 2025, and on Certain's return to independence retains about 37 per cent plus a share of future product revenue in exchange for continued engineering support [11]. New investors are therefore funding a company that pays a royalty to its largest shareholder and depends on that shareholder for engineering.
Finally, the geography. Michael Shanks, minister at the Department for Energy Security and Net Zero, framed the £3.5 million as backing British innovation and the storage Britain needs [13]. Part of the proceeds funds a grid-connected project in India, with the rest going to UK research and development [5]. That is a defensible commercial sequence, since first grid connections go where a counterparty will host them. It is not what the British energy security framing implies.
What to watch
- A published reconciliation from NESO of daily curtailment payments against the annual total, which would fix which growth curve the £8 billion forecast sits on.
- Any signed offtake or grid-connection milestone on the India project, the first evidence the manganese chemistry works outside a lab.
- Whether Ceres Power reduces its roughly 37 per cent stake or restructures the revenue share at the next round.
Clarity's read
What the record supports and how the coverage leans. The claims behind it follow.
Reality
- Evidence26
- Adoption14
- Hype gap+52
- Incentives78
- Confidence38
Claim ledger
Ranked by verification strength, evidence, and original report placement.
- [1]
Unlike Form Energy, Certain Energy has not yet demonstrated that its technology works at grid scale.
- [2]
Certain Energy, previously known as RFC Power, raised £10 million in a Series A round with the British Business Bank as lead investor.
- [3]
The British Business Bank led the round with an investment of £3.5 million.
- [4]
Centrica, Ceres Power Holdings and Catalytic Capital for Climate and Health (part of the Temasek Trust) also participated in the round.
- [5]
The funds will be used to finance a grid-connected project in India and to support research and development in the UK.
- [6]
Form Energy has raised more than $1.2 billion for iron-air storage and already has commercial contracts in place.
- [7]
Ore Energy has raised $43 million in the UK for iron-air storage, claiming it is ten times cheaper than lithium-ion; EnerVenue has raised $300 million for a metal-hydrogen alternative.
- [8]
Certain Energy uses manganese, the twelfth most common element in the Earth's crust, as its battery electrolyte, instead of lithium or vanadium.
- [9]
To increase storage duration the company enlarges the electrolyte tanks rather than adding more cells, so operators can extend storage by increasing tank size rather than installing new systems.
- [10]
Certain Energy was set up in 2017 as a spin-off from Imperial College London by professors Anthony Kucernak and Nigel Brandon, and took eight years to develop its technology.
- [11]
In September 2025 Certain Energy became a wholly owned subsidiary of Ceres Power; it is now independent again, with Ceres holding about 37 per cent and receiving a share of any future product revenue in exchange for continued engineering support.
- [12]
Executive chair Mark Selby said the renewable power market is held back by its vulnerability to external factors and that the answer is long-duration energy storage.
- [13]
Michael Shanks, minister of state at the Department for Energy Security and Net Zero, described the £3.5 million as the British Business Bank backing British innovation and helping develop long-duration storage to hold clean power for days rather than hours, and characterised it as grid infrastructure rather than a typical startup investment.
ReportedSupportedSource: Michael Shanks, minister of state, Department for Energy Security and Net ZeroView cited source - [14]
£1.5 million a day annualises to about £548 million a year, roughly a third of the £1.5 billion annual figure cited in the same account.
- [15]
Growing from £1.5 billion in 2025 to £8 billion in 2030 implies compound growth of about 40 per cent a year.
- [16]
Growing from the £548 million annualised run rate to £8 billion in 2030 implies compound growth of about 71 per cent a year.
- [17]
Certain Energy's £10 million round is about 0.8 per cent of the more than $1.2 billion Form Energy has raised, comparing nominal figures without currency conversion.
- [18]
The British Business Bank's £3.5 million is 35 per cent of the £10 million round.
- [19]
Last year the United Kingdom paid around £1.5 billion to renewable energy producers to reduce output, a sum that could reach £8 billion by 2030 according to the grid operator's expectations as reported.
- [20]
In 2025, Britain paid wind and solar farms £1.5 million a day to reduce their output.
- [21]
The global long-duration energy storage market was worth $3.6 billion in 2025 and is expected to reach $9.5 billion by 2035, a 10.5 per cent compound annual growth rate.
- [22]
Most of the growth in long-duration storage is currently driven by US-backed iron-air and mechanical storage companies receiving much larger amounts of funding.
- [23]
The technology has a round-trip efficiency of more than 75 per cent, and the company states the electrolyte can last 20 years with only slight degradation.
- [24]
Certain Energy states that manganese is cheaper than the alternatives and that its storage costs are about one-tenth of those of vanadium flow systems.
Sources
1 independent publisher whose own reporting we read for this story.
- techfundingnews.comCertain Energy raises £10M to tackle Britain’s £8B grid waste problem
1 article · August 26, 2026
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Topics
- UK grid curtailment costsFollow
- University SpinoutsFollow
- State-backed industrial policyFollow
- Flow batteriesFollow
- Long-duration energy storageFollow
- Climate and Energy Tech Venture FundingFollow
Entities
- Certain EnergyFollow
- British Business BankFollow
- Ceres PowerFollow
- CentricaFollow
- Catalytic Capital for Climate and HealthFollow
- Form EnergyFollow
- Ore EnergyFollow
- EnerVenueFollow
- Imperial College LondonFollow
- Department for Energy Security and Net ZeroFollow
- Mark SelbyFollow
- Tim von WerneFollow
- Michael ShanksFollow
- Stuart PaynterFollow
- Anthony KucernakFollow
- Nigel BrandonFollow