Swiss construction group Erne this week announced it was entering into a strategic partnership with FlexBase Group for the FlexBase Technology Center battery storage and AI data center project.

To be located on a 20,000 sqm (215,280 sq ft) site in Laufenburg in the canton of Aargau, Erne said the 500MW project will be the world’s largest battery storage system.

The companies are redeveloping a former Swissgrid building. According to a FlexBase brochure, the data center will total 600 sqm (6,500 sq ft), and will reportedly feature liquid cooling, be equipped with 8,000 sqm (86,100 sq ft) of solar, and offer its waste heat to the local district heating network.

Construction is scheduled to start in spring 2025.

Founded in 1906, Erne is a family-owned Swiss construction group. Giuseppe Santagada, CEO of the ERNE Group, said: "My personal commitment goes far beyond the realization of this project; it also includes the promotion of new technological skills and increasing the attractiveness of Laufenburg as a location for the vision of a prosperous region."

Swissgrid relocated its HQ from Laufenburg to Aarau around 2018. In its annual report from 2018 and 2019, the company said it also built two new data centers and migrated its IT infrastructure away from the Laufenburg site as part of the move.

Energy firm Axpo sold the building, which was previously home to the Laufenburg Electricity Company (Elektrizitäts-Gesellschaft Laufenburg AG) before Swissgrid, to real estate firm Entwicklungsgesellschaft Stern Laufenburg Ag in 2018. Terms were not shared – but the companies said the site would be turned into a business incubator dedicated to energy and secure communications.

The substation at the site – known as the "Star of Laufenburg" – was the first site at which the German, French, and Swiss power networks were interconnected and synchronized at the 220-kilovolt level, back in 1958. In 1967, the 380-kV country networks were interconnected for the first time at the same site.

Flexbase’s website notes the planned storage system will be a redox flow battery. Redox flow batteries see energy provided by two chemical components dissolved in liquids that are pumped through the system on separate sides of a membrane.

A wind tunnel for research and development purposes in the sports sector is reportedly also being built at the site.