When the Three Mile Island power plant in Pennsylvania was decommissioned in 2019, it heralded the symbolic end of America’s nuclear industry. In 1979, the facility was the site of the worst nuclear disaster in the nation’s history: a partial reactor meltdown that didn’t release enough radiation to cause detectable harm to people nearby, but still turned Americans against nuclear power and prompted a host of regulations that functionally killed most nuclear build-out for decades. Many existing plants stayed online, but 40 years later, Three Mile Island joined a wave of facilities that shut down because of financial hurdles and competition from cheap natural gas, closures that cast doubt over the future of nuclear power in the United States.
Now Three Mile Island is coming back, this time as part of efforts to meet the enormous electricity demands of generative AI. This morning, the plant’s owner, Constellation Energy, announced that it is reopening the facility. Microsoft, which is seeking clean energy to power its data centers, has agreed to buy power from the reopened plant for 20 years. “This was the site of the industry’s greatest failure, and now it can be a place of rebirth,” Joseph Dominguez, the CEO of Constellation, told The New York Times. Three Mile Island plans to officially reopen in 2028, after some $1.6 billion worth of refurbishing and under a new name, the Crane Clean Energy Center.
Nuclear power and chatbots might be a perfect match. The technology underlying ChatGPT, Google’s AI Overviews, and Microsoft Copilot is extraordinarily power-hungry. These programs feed on more data, are more complex, and use more electricity-intensive hardware than traditional web algorithms. An AI-powered web search, for instance, could require five to 10 times more electricity than a traditional query.
The world is already struggling to generate enough electricity to meet the internet’s growing power demand, which AI is rapidly accelerating. Large grids and electric utilities across the U.S. are warning that AI is straining their capacity, and some of the world’s biggest data-center hubs—including Sweden, Singapore, Amsterdam, and exurban Washington, D.C.—are struggling to find power to run new constructions. The exact amount of power that AI will demand within a few years’ time is hard to predict, but it will likely be enormous: Estimates range from the equivalent of Argentina’s annual power usage to that of India.
That’s a big problem for the tech companies building these data centers, many of which have made substantial commitments to cut their emissions. Microsoft, for instance, has pledged to be “carbon negative,” or to remove more carbon from the atmosphere than it emits, by 2030. The Three Mile Island deal is part of that accounting. Instead of directly drawing power from the reopened plant, Microsoft will buy enough carbon-free nuclear energy from the facility to match the power that several of its data centers draw from the grid, a company spokesperson told me over email.
Such electricity-matching schemes, known as “power purchase agreements,” are necessary because the construction of solar, wind, and geothermal plants is not keeping pace with the demands of AI. Even if it was, these clean electricity sources might pose a more fundamental problem for tech companies: Data centers’ new, massive power demands need to be met at all hours of the day, not just when the sun shines or the wind blows.
To fill the gap, many tech companies are turning to a readily available source of abundant, reliable electricity: burning fossil fuels. In the U.S., plans to wind down coal-fired power plants are being delayed in West Virginia, Maryland, Missouri, and elsewhere to power data centers. That Microsoft will use the refurbished Three Mile Island to offset, rather than supply, its data centers’ electricity consumption suggests that the facilities will likely continue to rely on fossil fuels for some time, too. Burning fossil fuels to power AI means the new tech boom might even threaten to delay the green-energy transition.
Still, investing in nuclear energy to match data centers’ power usage also brings new sources of clean, reliable electricity to the power grid. Splitting apart atoms provides a carbon-free way to generate tremendous amounts of electricity day and night. Bobby Hollis, Microsoft’s vice president for energy, told Bloomberg that this is a key upside to the Three Mile Island revival: “We run around the clock. They run around the clock.” Microsoft is working to build a carbon-free grid to power all of its operations, data centers included. Nuclear plants will be an important component that provides what the company has elsewhere called “firm electricity” to fill in the gaps for less steady sources of clean energy, including solar and wind.
It’s not just Microsoft that is turning to nuclear. Earlier this year, Amazon purchased a Pennsylvania data center that is entirely nuclear-powered, and the company is reportedly in talks to secure nuclear power along the East Coast from another Constellation nuclear plant. Google, Microsoft, and several other companies have invested or agreed to buy electricity in start-ups promising nuclear fusion—an even more powerful and cleaner form of nuclear power that remains highly experimental—as have billionaires including Sam Altman, Bill Gates, and Jeff Bezos.
Nuclear energy might not just be a good option for powering the AI boom. It might be the only clean option able to meet demand until there is a substantial build-out of solar and wind energy. A handful of other, retired reactors could come back online, and new ones may be built as well. Just yesterday, Jennifer Granholm, the secretary of energy, told my colleague Vann R. Newkirk II that building small nuclear reactors could become an important way to supply nonstop clean energy to data centers. Whether such construction will be fast and plentiful enough to satisfy the growing power demand is unclear. But it must be, for the generative-AI revolution to really take off. Before chatbots can finish remaking the internet, they might need to first reshape America’s physical infrastructure.
theatlantic.com