UK data center operator Era4 has unveiled more details of its plans to develop a former steel mill in Newport, Wales, into an up to 1GW AI campus.

The firm says the first stage of the development, which will be built on the former Liberty Steel site and be known as The Mill, will come online next year.

DCD reported in April that the company had received planning permission to develop the site, and that it planned to install modular data center units inside existing buildings.

According to the Era4 website, the 230-acre site will eventually offer up to 1GW of power, and house as many as 400,000 Nvidia Vera Rubin GPUs.

It is not clear how much of this power will be available when the data center opens next year. Era said the site will use “a mix of power which is responsibly sourced with long-term energy contracts that doesn’t impact local community or industry.” The data center will use a closed-loop system to keep water use to a minimum.

Liberty Steel still operates a plant on the site, but the building earmarked for the data center is not currently in use. Era4 said it plans to retain the factory’s original brick chimney “as a landmark, linking the new campus to the site’s industrial past.”

Launched last year as Carbon3.ai, Era4 rebranded earlier this year. The company revealed details of its AI platform in September 2025, claiming at the time that it would eventually comprise 100,000 GPUs, aiming to reach more than 30 locations.

It revealed plans for a modular AI data center in Derbyshire in November 2025, and in December said it had signed an agreement to deploy Nvidia Blackwell Ultra AI infrastructure with HPE's direct liquid-cooled servers. It saw a proposal for a site in Anglesey rejected, but has proposed another site in Canterbury, Kent, which will be powered by landfill gas.

Last month, the firm teamed up with another UK company, Civo, to launch a sovereign AI cloud.