Microsoft is planning to restart Three Mile Island Nuclear Power Plant to power its cloud and AI datacenters

Constellation Energy, the power company that owns the Three Mile Island power station in Pennsylvania (the site of the major accident in the 1970s), will restart a nuclear reactor if all goes according to plan. This is to meet an agreement made with Microsoft to provide carbon-free electricity to power their data centers.

The reactor that is coming back online, however, is not the same one that suffered a partial meltdown during the 1979 accident and has been dormant ever since. This was TMI Unit 2. TMI-Unit 1 was the adjacent reactor. It went back into operation again in 1985, and continued to run until 2019, when Constellation shut it down due to "poor economy."

Constellation says that after refurbishing TMI-Unit 1 and obtaining all the necessary federal and State approvals, it hopes to have the reactor operating by 2028. It also claims that restarting the nuclear reactor will "add about 835 megawatts (of carbon-free) energy to the grid." The plant will also be renamed "Crane Clean Energy Center," after Chris Crane. Crane was a nuclear energy "titan", who died earlier this summer.

Constellation's proposal has been praised by Pennsylvania politicians as well as the US Department of Energy. Dr Michael Goff is the acting assistant secretary of federal agency's Office of Nuclear Energy. He said that "always on, carbon-free nuclear power plays an important part in the fight against global warming and meeting the growing energy needs of the country."

Microsoft's data centres are the infrastructure for its cloud computing and storage services, which include new AI processing that is notoriously energy-hungry. Microsoft's VP of Energy Bobby Hollis said that this power contract, the largest Constellation has ever signed, is "a major milestone in Microsoft's effort to decarbonize grid." Separately we know that Microsoft is looking into using "small modules reactors" and microreactors to power its data centres.

Bill Gates, the Microsoft founder, is also involved in nuclear energy. TerraPower, a company he founded back in 2006, broke ground earlier this year on a new Wyoming plant.

Gates told NPR that the US didn't need much new electricity, but with the increase in electric cars, buses and heat pumps for heating homes as well as electric heat pumps in general, demand will go up. "And these data centers add to that." The big tech companies are looking for ways to facilitate more power so that these data centres can serve the exploding AI demands.