Three Mile Island Set to Restart to Power Microsoft’s AI Data Centers

The shuttered Three Mile Island nuclear plant will be brought back online to sell power to Microsoft for its data centers under a deal announced Friday, as the tech giant’s energy needs rocket in the age of artificial intelligence.

The agreement between Microsoft and Constellation Energy, the dormant plant’s owner, would see the site’s Unit 1 reactor put back into service by 2028. The Pennsylvania plant’s other reactor, Unit 2, was destroyed in a partial meltdown in 1979 in what remains the worst nuclear accident in American history.

The plant’s previous owner, Exelon, shut down the site in 2019, citing financial difficulties. If the new deal with Microsoft is approved, it would mark the first time that a U.S. nuclear power plant is brought out of retirement after being decommissioned.

Constellation said it also plans to seek regulatory approval to extend the revivified plant’s operations until 2054 at the earliest. Microsoft would buy all of the plant’s power for 20 years.

Before it closed, the plant had a generating capacity of 837 megawatts—enough to power more than 800,000 homes. Constellation says the long-term operation of the Unit 1 reactor was “not impacted by the Unit 2 accident” but that restarting will nevertheless require “significant investments” to restore the plant, including its turbine, generator, and cooling and control systems.

The destroyed Unit 2 is sealed off, with its partially melted core removed years ago and shipped to the U.S. Department of Energy’s Idaho National Laboratory, the Associated Press reports. The remnants of the site inside the containment building remain extremely radioactive.

“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 said on a call with investors Friday morning, according to CNBC. Dan Eggers, the company’s CFO, said they would invest $1.6 billion in restarting the plant over the next four years.

The tech industry’s demand for electricity to power its data centers is expected to dramatically increase as the AI boom continues in coming years. A report from Goldman Sachs earlier this year estimated that data center power demand will surge 160 percent by 2030, meaning they’ll use 8 percent of all U.S. power compared with the 3 percent they used in 2022.