Constellation Energy to restart Three Mile Island nuclear plant, sell the power to Microsoft for AI

Constellation Energy plans to restart the Three Mile Island nuclear plant and will sell the power to Microsoft, demonstrating the immense power needs of the tech sector as they build out data centers to support artificial intelligence.

Constellation expects the Unit 1 reactor at Three Mile Island near Middletown, Pennsylvania to come back online in 2028, subject to approval by the Nuclear Regulatory Commission, the company announced Friday. Constellation also plans to apply to extend the plants operation to at least 2054.

Unit 1 ceased operations in 2019 as nuclear power struggled struggled to compete economically with cheap natural gas and renewables. It is separate from the reactor that partially melted down in 1979 in the worst nuclear accident in U.S. history.

Microsoft will purchase electricity from the plant to match the energy its data centers consume with carbon-free power. Constellation described the agreement with Microsoft as the largest power purchase agreement that the nuclear plant operator has ever signed.

Constellation stock jumped nearly 7% in early trading.

Electricity demand from data centers is expected to surge in the coming decades as the tech sector ramps up artificial intelligence, threatening to strain the electric grid. While estimates vary, Goldman Sachs has forecast data centers will consume 8% of total U.S. electricity demand by 2030, compared to 3% currently.

Tech companies are hunting for nuclear power to meet that growing electricity demand while adhering to their climate goals. In March, Amazon Web Services bought a data center campus from Talen Energy Corporation that will be powered by the Susquehanna nuclear plant, also in Pennsylvania, in a first-of-its-kind deal.

There is growing bipartisan support from the federal and state governments to revive the nuclear industry after a decade-long wave of reactor shutdowns.

Three Mile Island would be the second nuclear plant to restart operations in U.S. history. The Palisades nuclear plant in Michigan would be the first, with that plant expected to return to service at the end of 2025.