Mistral Bruyeres-le-Chatel data center, Île-de-France, France

Eclairion is building a data center in the park of the chateau at Bruyeres-le-Chatel, in Essonne outside Paris, France, on four hectares the town's local plan had protected as a natural zone until the council reclassified it for construction in 2018. Owned by High Performance Capital, Eclairion offers up to 60 megawatts of power in separate modular data centers. In February 2025 it said it would host Mistral AI's new training cluster, and DCD reported in March 2026 that the site was still under construction.

The project was put together by historian and urban planner Michel Carmona, with developer Patrice Cavalier putting in the first 10 to 12 million euros; Francois Sabatino is Eclairion's president. Mistral AI takes half the computing power, with the rest meant for companies such as Safran, Thales, Dassault Systemes, Valeo, Air France and Renault. GPU cloud company Fluidstack said it would deploy a cluster at the 40 megawatt site, but Bloomberg reported in March 2026 that Fluidstack had cancelled that deal to focus on the US.

The site's electrical capacity is 60 megawatts, which Le Chiffon compared to the yearly consumption of Bordeaux's 260,000 residents, and it draws about 90 cubic meters of water a day from the public network, up to 423 on some days, almost as much as the whole town uses. Nine diesel generators totaling 49.5 megawatts stand behind it, fed by nine buried tanks of 40 cubic meters each.

The municipal opposition group Bruyeres-le-Chatel Ensemble criticized the plan at a December 2018 council meeting over water, electricity and the buried fuel, and has since declined to comment. Carmona says regional prefect Michel Cadot raised objections over concrete and damage to the forest before the project was pushed through as a matter of national interest, because the project is backed by the Commissariat for Atomic Energy (CEA), based nearby. In November 2024 the Ile-de-France region voted three million euros of support for Eclairion.