On September 20, 2024, Constellation Energy announced a 20-year power purchase agreement with Microsoft that would restart Unit 1 at Three Mile Island - the reactor that ran safely for decades and was not involved in the site’s 1979 partial meltdown - and rename the facility the Crane Clean Energy Center. Constellation called it the company’s largest-ever power purchase agreement, adding roughly 835 megawatts of carbon-free generation to the grid, with the plant expected back online in 2028. The same announcement was filed with the Securities and Exchange Commission as an exhibit to a Form 8-K, making the deal a matter of first-party corporate and regulatory record rather than rumor.
The detail that made the deal a landmark was the buyer and the reason. Constellation’s president and CEO Joe Dominguez framed it directly in terms of the new demand: “Powering industries critical to our nation’s global economic and technological competitiveness, including data centers, requires an abundance of energy that is carbon-free and reliable every hour of every day.” Microsoft was buying the output to match the power its datacenters draw with carbon-free energy. The mental image is stark and that is why it stuck: a name synonymous with America’s worst commercial nuclear accident was being brought back to life specifically to feed the computing infrastructure behind AI.
The deal turned an abstract worry into a concrete fact. The library’s account of AI compute describes the spiraling demand for processors and the electricity to run them; this is the moment that demand became large enough to justify restarting a shuttered nuclear plant on a 20-year contract. It signaled that for the largest AI operators, securing dedicated, round-the-clock, carbon-free power had become a strategic problem on the same level as securing chips - and that the energy footprint of AI was no longer a side concern but a driver of decisions about national power infrastructure.