Crane Clean Energy Center (Three Mile Island Reactivation)

Constellation Energy, in partnership with Microsoft, is restarting the undamaged Unit 1 reactor at Three Mile Island, rebranded as the Crane Clean Energy Center. The facility will provide 835 MW of carbon-free electricity exclusively to Microsoft under a 20-year power-purchase agreement (PPA) extending to 2054. This deal represents the first-ever restart of a decommissioned nuclear reactor in the United States and highlights the extreme energy demands of next-generation AI data centers.

The restart project involves a $1.6 billion investment to upgrade the plant’s turbine, generator, main transformer, and control systems. Unit 1 is physically separate from Unit 2, which was the site of the 1979 accident and is currently being decommissioned. The Crane Clean Energy Center is expected to be operational by late 2028, providing the firm, “always-on” baseload power required for Microsoft’s AI training clusters while contributing $16 billion to Pennsylvania’s GDP over the life of the agreement.