Microsoft signs 20‑year pact to restart Three Mile Island nuclear plant for AI data centers

Microsoft and Constellation Energy have entered a 20‑year power purchase agreement to bring Unit 1 of the Three Mile Island nuclear reactor in Pennsylvania back online. The deal will supply roughly 835 MW of carbon‑free electricity to power Microsoft’s data centers that train artificial‑intelligence models. The restart, costing about $1.6 billion, is slated for commercial operation by 2028, with regulators granting a waiver in June 2026 to accelerate grid connection. The project is projected to create around 3,400 jobs and generate more than $3 billion in tax revenue over its life, while also influencing regional energy markets and limiting capacity available to other large users such as crypto miners.

The agreement highlights the growing reliance of major tech firms on dedicated, low‑carbon energy sources to support AI workloads, marking a notable shift toward nuclear power in the data‑center sector.