Equinix is investing in the future of digital infrastructure by incorporating advanced nuclear energy alongside renewables and grid contracts. The global data center leader has signed a pre-order agreement with French start-up Stellaria for electricity from its first commercial molten salt reactor, the ‘Stellarium,’ planned for deployment in 2035.
Equinix has secured the first power capacity tranche from a future Stellarium reactor, marking Stellaria’s first capacity commitment. This long-term strategy aims to provide reliable, low-carbon power for Equinix’s expanding AI-ready, high-density data centers, which are increasing power demand and resiliency needs globally.
Stellaria, originating from the French Alternative Energies and Atomic Energy Commission (CEA), one of Europe’s top nuclear research bodies, has designed a compact molten salt reactor with a core volume of about four cubic meters. It can operate with various nuclear fuels, including uranium, plutonium, MOX, minor actinides, and thorium. Stellaria asserts that Stellarium is the first reactor concept using liquid fuel capable of “destroying more waste than it produces,” serving both power generation and waste reduction.
Diversifying The Energy Mix
For Equinix, this agreement is part of a broader strategy to diversify its energy sources beyond traditional power purchase agreements and grid-based renewables. In August, Equinix announced partnerships with five alternative energy providers, including Stellaria, to support its AI-optimized data centers. The Stellaria deal is the most forward-looking of these initiatives, suggesting that some data center campuses might eventually be located near dedicated nuclear microreactors.
Régis Castagne, Managing Director of Equinix France, stated that Stellaria was chosen because it’s among the few vendors capable of making high-density AI data centers both energy-resilient and low-carbon. Stellarium units are designed to produce around 250 MWe of continuous power, with Stellaria highlighting the potential for 24/7 firm output and the ability to use certain categories of nuclear waste as fuel. For large-scale data center operators, this combination of baseload power, carbon-free generation, and reduced on-site waste storage is highly appealing.
California-based Equinix operates over 270 data centers in 77 metropolitan areas worldwide. In Europe, the company already reports 100% renewable coverage for its operations and has actively pursued long-term renewable power purchase agreements, including in France. Advanced nuclear is seen not as a replacement for renewables, but as a complementary, dispatchable power source supporting the extreme, often fluctuating loads associated with AI training clusters and GPU-rich infrastructure.
For Stellaria, the Equinix agreement is a significant commercial milestone in a market where most advanced reactor projects remain in the design and licensing phase. CEO Nicolas Breyton described the deal as a pivotal moment that validates Stellaria’s strategy and signals demand ahead of planned Stellarium deployments starting in 2035, pending regulatory approvals and industrialization.
The use of molten salt reactors (MSRs) for data center power is speculative but technically promising. MSRs use molten fluoride or chloride salts as both coolant and, in some designs, as a carrier for dissolved nuclear fuel. They operate at low pressure but high temperature, offering inherent safety features, high thermal efficiency, and the potential for alternative fuel cycles, including thorium-based systems that breed fissile uranium-233. They can be configured for fast or epithermal neutron spectra, allowing for burning transuranic waste or optimizing different fuel strategies.
Nuclear Safety Regulations
The path to commercialization is complex. MSR designs must navigate stringent nuclear safety regulations, address materials challenges like corrosion in hot salt environments, manage fuel cycle logistics, and gain public acceptance. Various design variants exist, and standardization is limited. Stellaria must demonstrate not only technical feasibility but also bankability, manufacturability at scale, and competitive levelized cost of electricity.
From a digital infrastructure perspective, the Equinix–Stellaria agreement highlights the rapidly changing power profile of AI-era data centers. As rack densities increase, workloads become more continuous, and AI training clusters behave more like industrial loads than traditional IT, operators are exploring options beyond incremental efficiency gains and grid contracts. Co-locating or closely siting advanced nuclear capacity could offer latency-free, predictable power
