A UK Startup's $12.3M Bet on Fixing a Volatile Grid

Jan de Vries · 2026-08-26

Picture this: a power grid so unpredictable that governments are paying billions just to tell renewable energy sources to shut down. It sounds wild, but that's exactly what's happening. And it's creating a massive opportunity for energy storage. That's where Certain Energy, a UK startup born from Imperial College London, comes in. They just landed a $12.3 million Series A funding round. They're betting their tech can be the solution to a very expensive, very modern problem. ### The Big, Expensive Problem with Renewables The core issue is simple. The sun doesn't always shine, and the wind doesn't always blow when we need power. So, sometimes we've got a huge surplus of green energy, and other times, a dangerous shortage. The UK government spent about $1.9 billion last year simply paying renewable providers to *stop* generating when production was too high. If we don't fix this, experts warn those costs could balloon to over $10 billion annually by 2030. That's just throwing money away. And it's holding the entire green energy transition back. ### What Certain Energy is Doing Differently Certain Energy, previously known as RFC Power, is developing a specific kind of battery called a manganese flow battery. It's designed for what's known as long-duration energy storage (LDES)—meaning it can store power for hours or even days, not just minutes. - They use manganese, which they call the twelfth most abundant element in the Earth's crust. - Their system stores energy in liquid electrolytes in external tanks. Think bigger tanks, longer storage. - They claim a 20-year operating life and efficiency over 75%. - Crucially, they say their design could slash storage costs to about one-tenth of other comparable flow battery systems. The idea is to capture the excess energy from a windy or sunny day and save it for a calm, cloudy one. It's like having a giant, efficient reservoir for electricity. ### The Funding and the Bigger Picture The $12.3 million round was led by the British Business Bank, which put in $4.3 million. They were joined by big names like Centrica Energy and Temasek Trust. This isn't happening in a vacuum, either. It's part of a huge wave of investment into European grid-tech companies. In 2026 alone, similar startups have raised well over $180 million. Mark Selby, Executive Chair of Certain Energy, put it bluntly: "The answer is long duration energy storage... we have the technology and now the funding to deliver highly efficient, affordable batteries, based on abundant materials, to make this a reality." Charlotte Lawrence from the British Business Bank added that the value is "clear" as grids become more volatile worldwide, highlighting the tech's potential for a strong return on investment while cutting overall energy needs. ### Why This Matters for the Future Grid This isn't just about one startup. It's about building a smarter, more resilient power system. Lithium-ion batteries are great for short bursts, but for truly balancing supply over longer periods, alternatives like flow batteries are critical. Certain Energy is positioning its tech as that essential complement—a tool to finally harness the full potential of wind and solar, and stop wasting both energy and money. It's a race to build the backbone of a clean grid. And with this funding, Certain Energy just got a serious boost to move from the lab toward real-world, grid-scale deployment.