IN Brief:
- Certain Energy, formerly RFC Power, has completed a £10 million Series A funding round.
- British Business Bank invested £3.5 million alongside Centrica, Ceres, and Temasek Trust's C3H.
- Funding will support an MWh-class Indian grid project, expanded UK research, and commercial supply-chain development.
Certain Energy has raised £10 million in Series A funding to commercialise its manganese-based flow battery technology, rebranding from RFC Power as it moves towards MWh-scale grid deployment.
The British Business Bank led the round with a £3.5 million investment. Centrica, Ceres Power, and Temasek Trust’s Catalytic Capital for Climate and Health also participated, with the capital intended to support technology scale-up, deployment, and development of a repeatable supply chain.
Certain Energy plans to build a grid-connected MWh-class system in India, expand its research facilities in the UK, and prepare its technology for volume production. The company was founded in 2017 from research at Imperial College London and has remained based around the university’s White City innovation ecosystem.
Its electrochemistry combines elements of flow-battery and fuel-cell operation, using a patented hydrogen-manganese system to convert electricity into stored chemical energy and return it later.
Duration is separated from stack power
The principal engineering argument behind flow batteries is the ability to separate much of the energy capacity from the electrochemical stack that determines power. Adding longer discharge duration can rely more heavily on increasing the quantity of stored electrolyte rather than multiplying complete battery modules in direct proportion to every additional megawatt-hour.
Certain Energy uses manganese as a key storage material and says its design can extend discharge from hours towards much longer periods by increasing storage capacity around the core electrochemical system. Imperial describes manganese as the twelfth most abundant element in the Earth’s crust.
That architecture is aimed at a different part of the flexibility market from batteries optimised principally for short-duration response. Lithium-ion systems benefit from an enormous manufacturing base and high power density, but their economics become increasingly dependent on the number of cells required as energy duration increases.
A flow-battery system can have a different cost relationship between MW and MWh because tanks and stored electrolyte contribute much of the additional duration. The electrochemical stack still has to be sized for the required power, while pumps, controls, hydrogen equipment, power electronics, and other balance-of-plant systems remain necessary regardless of tank size.
Certain Energy currently states a target of more than 75% system round-trip efficiency and a design life exceeding 20 years. It is also targeting an energy-storage cost below $20/kWh for the storage component as the technology reaches commercial scale.
Those are company performance and cost targets rather than operating results from a mature commercial fleet. The planned MWh-scale deployment will therefore be important because the economics of long-duration storage depend on complete plant performance rather than the electrochemistry in isolation.
Auxiliary consumption can be material in a flow system. Pumps, thermal management, controls, hydrogen handling, power conversion, and other equipment consume energy and influence round-trip efficiency, while maintenance and component life affect the availability of the complete installation.
The balance of plant also determines how readily the technology can become a grid asset. Transformers, switchgear, protection, metering, controls, and grid-code functions have to operate alongside the electrochemical process, and lenders or utilities will expect warranties and performance data that encompass the whole plant.
The planned Indian project moves that testing into a more demanding environment. An MWh-class grid installation has to pass through equipment manufacture, shipping, construction, electrical integration, commissioning, network compliance, and sustained field operation rather than controlled laboratory cycling.
Operating data will allow potential customers to compare actual efficiency, availability, maintenance requirements, degradation, and usable capacity with the assumptions behind the commercial model. A successful demonstrator does not in itself establish bankability, but it provides evidence that cannot be obtained from smaller laboratory stacks.
Certain Energy is entering a market in which no single storage technology covers every timescale. Lithium-ion batteries dominate short-duration deployment, pumped hydro provides large energy reservoirs where geography permits, and technologies including compressed air, thermal storage, hydrogen, and alternative flow chemistries are competing for longer-duration requirements.
The useful comparison is therefore not whether one chemistry is universally superior. It is whether the complete system can provide the required duration and cycling profile at an acceptable lifetime cost while meeting the response, footprint, safety, and connection requirements of the intended project.
Certain Energy’s case relies heavily on the availability and cost of manganese and on the ability to scale energy capacity without building a cell-manufacturing model comparable with a lithium-ion gigafactory. The company describes its production approach as one where larger projects require larger tanks rather than proportionally larger manufacturing plants.
Commercialising that model requires a supply chain capable of producing stacks, electrolyte systems, vessels, power equipment, controls, and supporting hardware with consistent quality. Moving from bespoke prototype construction into repeatable projects is therefore as much a manufacturing problem as an electrochemistry problem.
The involvement of Ceres provides an additional engineering link. Ceres acquired RFC Power before the latest funding round and is participating again as Certain Energy becomes a separately financed commercialisation business.
For the UK, the development illustrates the familiar challenge of retaining university-derived energy technology through the scale-up stage. Laboratory results can attract research funding, but grid equipment has to survive a much more capital-intensive period in which manufacturing, warranties, field testing, and customer qualification are built before meaningful project revenue arrives.
The £10 million round finances the next part of that process rather than completing it. Certain Energy now has to demonstrate whether its manganese system can deliver the efficiency, lifetime, cost, and scaling characteristics claimed when the technology is assembled as a complete MWh-class power asset and operated on a live electricity network.
