Deep beneath the Swiss town of Laufenburg, a cavern is being prepared to house one of the world’s largest redox flow batteries, a system that will store 2.1 gigawatt‑hours of electricity and deliver up to 1.2 gigawatts of power when the grid needs it.
The project, led by FlexBase, is designed to act as a shock absorber for power flows, smoothing out the fluctuations that come with high shares of renewable energy and helping to keep Europe’s transmission network stable.
Strategic partners and technological choices
FlexBase has teamed up with Invinity Energy Systems, a specialist in vanadium‑based flow batteries, to supply the core electrochemical components. The collaboration also brings an AI‑driven data centre and a district‑heating network into the underground site, creating a multi‑use facility that can store energy, process data and supply heat.
The battery’s electrolyte is an aqueous solution with a high water content, making it non‑flammable, non‑explosive and fully recyclable. Such safety attributes are crucial for an underground installation that will operate for decades.
Over the next three decades the plant is expected to avoid roughly 82,700 U.S. tons of CO₂ emissions, while also generating an estimated 300 jobs during construction and operation. The total investment is projected to fall somewhere between $1.2 billion and $6.2 billion, with initial commissioning slated for 2028 and full operation targeted for 2029.
By storing surplus renewable electricity when the wind blows and the sun shines, the Laufenburg battery will release power on demand, helping to balance frequency and voltage across the continental grid. Its role is reminiscent of a shock absorber, dampening spikes and preventing blackouts.
The initiative underscores how large‑scale storage can mitigate the intermittent nature of wind and solar, turning excess generation into a reliable resource that can be dispatched whenever the system needs it.