A Swiss firm is constructing what it claims is the world’s most powerful redox‑flow battery, designed to store vast amounts of renewable energy and help stabilise both the Swiss and European power grids. The FlexBase group is currently excavating a 27-metre-deep pit – longer than two football pitches – in Laufenburg, canton Aargau, to house the underground battery installation. “We will be able to inject or absorb up to 1.2 gigawatts (GW) of electricity in a few milliseconds, equivalent to the power of the Leibstadt nuclear power plant [also in canton Aargau near the German border],” co-founder Marcel Aumer told Swiss public broadcaster RTS. The mammoth battery storage system is part of a future Laufenburg Technology Centre, a 20,000m² complex including an AI data centre, offices and laboratories. FlexBase plans to put its giant battery into operation in 2029 and hopes to generate around 300 jobs. Privately financed, the project carries a price tag ranging from CHF1-5 billion …