Switzerland builds world’s most powerful redox-flow battery
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.
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Switzerland builds world’s most powerful redox-flow battery
The FlexBase groupExternal link 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 CentreExternal link, 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 ($1.2-6.2 billion).
Watch our short video about the Laufenburg redox-flow battery project.
How redox-flow batteries work
Unlike lithium‑ion batteries, which store energy in solid electrodes, redox‑flow batteries use liquid electrolytes.
Giant tanks hold the liquid electrolytes, while stacks of cells above them convert the stored chemical energy into electricity.
The system is recharged using surplus renewable electricity – mainly solar and wind – which feeds energy back into the grid during peak demand.
Vital component of future grid
Swissgrid, operator of the national high‑voltage network, plans to connect to the Laufenburg site – marking a first for Switzerland.
Swissgrid believes large batteries like these will become a key component of Switzerland’s future grid network.
“Large batteries can store energy when there is a lot of it and release it when it is needed. So in the future, with wind production that will fluctuate according to the weather, having this flexibility can help stabilise the grid,” explained Gabriele Crivelli, a Swissgrid spokesperson.
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Such installations can also reduce the risk of power outages and help meet soaring electricity demand from data centres powered by artificial intelligence (AI).
While redox‑flow technology is still emerging in Europe, it is already well established in other regions.
“The Asian market, with Japan in the lead, has developed this technology considerably. Today, Japan, China and South Korea are about seven years ahead of us Europeans,” said Marcel Aumer.
Tobias Schmidt, a professor of energy and technology policy at the federal technology institute ETH Zurich, carried out a studyExternal link in 2020 analysing the battery technologies likely to prevail worldwide in the future. He believes that redox‑flow technology, as planned in Laufenberg, “has no chance”. “I don’t know the exact figures for Laufenburg. But I’m surprised. I wouldn’t invest in this technology,” he told Swiss public broadcaster SRFExternal link last year.
Schmidt believes the future lies with metal-ion batteries, such as “lithium-ion”. “The huge market for lithium-ion batteries is electric vehicles. There is a lot of investment in this area, especially in China, and the batteries are rapidly becoming better and cheaper. The learning curve for this technology is enormous,” he told SRF.
The Swiss professor co-authored a 2025 studyExternal link that indicates that post-lithium-ion battery storage (a new generation of storage), particularly sodium-ion, fully benefits from the learning curve of lithium-ion batteries. “It is therefore really hard to beat the metal-ion battery trajectory,” Schmidt told Swissinfo.
Adapted from French using AI/sb with additional input/ts
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