Inside Switzerland's massive underground flow battery that could power 210,000 homes for a day without lithium-ion cells

Switzerland is building a massive underground flow battery by 2029. It will store 2.1 GWh of renewable power, enough to power 210,000 homes daily. This project uses vanadium flow technology, which engineers say "experience less performance degradation." It aims to stabilize European grids and support a new AI data center.