In a quiet corner of northern Switzerland, construction crews are currently digging a hole so large it could swallow two soccer pitches and a small skyscraper.

It is a billion-dollar project being designed to solve one of the most modern persistent issues: how to keep the lights on when the wind stops blowing.

At the heart of this massive excavation in Laufenburg is a redox flow battery, a concept first theorized in 1879.  While the tech was polished by NASA during the Space Race, it has long sat in the shadow of lithium-ion. 

Now, the Swiss energy firm FlexBase is betting billions that this Victorian-era idea is the key to stabilizing the European power grid.

Once the construction is complete, it is expected to be the “world’s most powerful redox flow battery” stored in an 88 ft (27 m) deep hole. This billion-dollar facility aims to stabilize the European power grid and support high-demand AI data centers.

“We will be able to inject or absorb up to 1.2 gigawatt-hours (GWh) of electricity in a few milliseconds, equivalent to the power of the Leibstadt nuclear power plan” Marcel Aumer, FlexBase co-founder, told Swissinfo.ch. 

Safer redox flow battery

Compared to standard phone batteries, which eventually wear out or overheat, redox flow batteries use large tanks of liquid electrolytes to safely store power rather than solid electrodes. These are non-flammable, highly recyclable, and don’t degrade over time. 

A redox flow battery stores energy by pumping two water-based chemical electrolytes from large tanks through a central cell. As the liquids pass a separating membrane, ions transfer between sides to charge or discharge power. 

Because the chemical process is “inert,” these batteries can be charged and discharged almost indefinitely, making them a virtually eternal solution for large-scale energy storage.

These systems capture surplus solar and wind power, converting the stored chemical energy back into electricity through stacks of cells whenever the grid hits peak demand. It is a scalable, liquid-based alternative designed to balance the ebb and flow of renewable energy.

Composed of 75 percent water, the electrolyte is a non-toxic and resource-efficient solution, making it one of the most environmentally friendly energy storage options on the market.

Once operational, the system will deliver a storage capacity exceeding 2.1 GWh. According to the company’s website, this equates to supporting 1 million households for 5 hours, or sustaining the energy needs of 210,000 households for a full 24-hour cycle.

Victorian solution for an AI future

Slated for completion in 2029, this mammoth battery is the anchor of the 20,000 215,000-sq-ft (~20,000-sq-m) Laufenburg Technology Center, a sprawling hub that will integrate AI data centers, laboratories, and offices. 

Reportedly, the privately funded project, which carries a massive investment between $1.2 billion and $6.2 billion, is expected to revitalize the local economy by creating approximately 300 new jobs.

Beyond simply preventing blackouts, this facility is specifically designed to quench the massive power thirst of local AI data centers.

Artificial intelligence needs a constant, non-stop flow of electricity to function. However, because wind and solar energy can be unpredictable, there is a gap between the energy Europe produces and the steady power these data centers require. FlexBase aims to provide a constant connection for the future of AI.