Flexbase Begins Construction on World’s Largest Battery Storage System and AI Data Center in Switzerland
May 15, 2026
Flexbase Begins Construction on World’s Largest Battery Storage System and AI Data Center in Switzerland
Energy provider Flexbase has broken ground on what is set to become the world’s largest battery energy storage system (BESS) in Laufenburg, Switzerland, marking a significant milestone in the integration of large-scale renewable energy and high-performance computing infrastructure. The project, known as the Laufenburg Technology Center, is located in the northern canton of Aargau and will combine a massive redox flow BESS facility with a 480MW AI data center, underscoring the growing convergence of energy storage and digital infrastructure.
The BESS facility will eventually reach a battery capacity of 1.6GW and a storage capacity of 2.1GWh, making it the largest of its kind globally. Swiss construction firm Erne is overseeing the build, which is scheduled for completion by 2029. Total costs are estimated to range between 1 billion and 5.5 billion Swiss francs ($1.27 billion to $7 billion). The site is strategically positioned near the ‘Star of Laufenburg,’ a major substation that serves as a key interconnection hub for both the Swiss and broader European electricity grids.
Flexbase has highlighted the advantage of this location, stating in 2024 that connecting to the substation “allows the battery storage system to reach its maximum potential by contributing optimally to national and international grid stability, while at the same time minimising power transmission losses.” The redox flow technology employed at the facility stores energy in liquid electrolytes held in two separate tanks, where electrochemical reactions can be triggered to absorb or discharge electricity. Proponents of this technology argue it offers superior safety and scalability compared to lithium-ion systems, as it is non-flammable and expansion only requires larger liquid tanks.
Excavation pits nearly 30 meters (98 feet) deep are currently under construction to accommodate the massive BESS. Flexbase claims the redox flow batteries will eventually be capable of supplying electricity to up to 210,000 households for a full day. The adjacent data center, described by Flexbase as Switzerland’s “first sovereign AI factory,” will occupy 600 square meters (6,500 square feet), feature a liquid cooling system, and stand at least 30 meters high to accommodate a waste heat recovery system. However, according to local outlet Südkurier, construction of the data center system will now be delayed until 2029.
The Laufenburg Technology Center was originally conceived as part of broader upgrades to Switzerland’s electricity grid, which is preparing for increased supply from new renewable energy installations and rising demand—much of it expected from the data center sector. Analysis published last year in the Zürcher Oberländer found that the sector’s power needs in Switzerland grew from 2.1 to 4 terawatt hours between 2019 and 2024. Although the data center market in Aargau remains small—with only two facilities operated by Green—the Flexbase project signals a major shift toward co-locating energy storage and AI compute capacity in the region.
Source: datacenterdynamics
