• Constellation Energy plans to restart the Unit 1 reactor at Three Mile Island.
• It will sell the power to Microsoft to support the power needs of data centers.
• Unit 1 is separate from the reactor that partially melted down in 1979 in the worst nuclear accident in U.S. history.
• Constellation will rename the plant the Crane Clean Energy Center.

Constellation Energy plans to restart the Three Mile Island nuclear plant and will sell the power to Microsoft, demonstrating the immense energy 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 plant's operations to at least 2054.

Constellation stock jumped about 15% in trading. Shares have more than doubled year to date.

Microsoft will purchase electricity from the plant in a 20-year agreement 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.

"The decision here is the most powerful symbol of the rebirth of nuclear power as a clean and reliable energy resource," Constellation CEO Joe Dominguez told investors on a call Friday morning.

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.

Constellation will rename the plant the Crane Clean Energy Center. The plant is named after Chris Crane, who was CEO of Constellation's former parent company and passed away in April.

Constellation will invest $1.6 billion in restarting the plant through 2028, including on nuclear fuel, Chief Financial Officer Dan Eggers told investors during the call.

Tech hunts for nuclear

Electricity demand from data centers is expected to surge in the coming decades as the tech sector ramps up AI, 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 with 3% currently.

Power demand is also surging from the expansion of domestic manufacturing and the adoption of electric vehicles. Rystad Energy has forecast that data center and electric vehicles alone will add 290 terawatt hours of electricity demand by the end of the decade, equivalent to the entire consumption of the nation of Turkey.

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 that will be powered by the Susquehanna nuclear plant, also in Pennsylvania, in a first-of-its-kind deal. Oracle recently said it is designing a data center that will be powered by three small nuclear reactors.

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.

Restart process

Constellation anticipates that the NRC will complete the review of Three Mile Island in 2027, Eggers said. The review includes a safety and environmental impact study.

"Based on our expertise on plant licensing and regulatory processes and through observation of the Palisades restart, we are highly confident we'll be able to restore the plant's operational licensing authority to the same state that existed prior to the shutdown in 2019," Eggers said.

The nation's largest grid operator, PJM Interconnection, will also have to review Three Mile Island's impact on the grid before the nuclear plant can restart, Eggers said. Constellation plans to submit a grid interconnection request to PJM next year, the executive said.

Eggers said the plant could potentially restart earlier than expected if PJM embraces changes that speed up interconnection requests to address tightening power supplies in the 13-state, primarily Mid-Atlantic region that the grid operator serves.

"In this rebirth, we see the most powerful sign that America will turn to the enduring promise of nuclear energy, an old and loyal ally that is renewed and ready to light the way forward," Dominguez said.