For five years, Reactor One at Pennsylvania’s Three Mile Island nuclear power plant has been dormant. Now, thanks to a deal with Microsoft, the reactor will be restarted in 2028 — this time, for the sole purpose of supplying the tech company with a ton of low-carbon electricity.
It’s all part of an ongoing flirtation between Substantial Tech and nuclear power. In March, Amazon Web Services agreed to buy the nuclear-powered Susquehanna data center Pennsylvania Station. During an event at Carnegie Mellon University on September 18, Alphabet CEO Sundar Pichai Small modular nuclear reactors were mentioned as a potential energy source for data centers. The connections don’t end there: OpenAI CEO Sam Altman chairs the boards of nuclear startups Oklo and Helion Energy.
The AI boom has left tech companies looking for low-carbon energy sources to power their data centers. International Energy Agency It is estimated that electricity demand from AI, data centers, and cryptocurrencies could more than double by 2026. Even low estimates say the additional demand would be equal to all the electricity used in Sweden or — in the case of high consumption — Germany.
This surge in energy demand is music to the ears of the nuclear industry. U.S. electricity demand has been fairly stable for decades, but the sheer scale and intensity of the AI boom is changing that vigorous. One report from December 2023 from an energy consulting company announced the end of the era of flat energy demand thanks to growing demand from data centers and industrial facilities. The report forecasts that peak electricity demand in the U.S. will raise by 38 gigawatts by 2028, or roughly 46 times the capacity of Three Mile Island’s first reactor.
“[AI] is really picking up steam and getting a lot of attention in the energy industry,” says John Kotek, senior vice president of policy development and public affairs at the Nuclear Energy Institute, a nuclear industry trade association. Kotek says there’s also a national security issue. “People rightly see AI as a competition between the U.S. and our global competitors.” The U.S. falling behind in the AI race because it doesn’t have enough power “is something that’s really causing people to pay attention to it,” he says.
Nuclear power is attractive to technology companies because it provides low-carbon electricity around the clock, unlike solar and wind, which operate intermittently unless they are combined with some form of energy storage. Reactivating reactor one will provide Microsoft with 835 megawatts of low-carbon power over the 20-year life of the contract. Because Microsoft has committed to negative carbon dioxide emissions by 2030spiraling demand for electricity from AI poses a sedate threat to the company’s climate plans unless it finds low-carbon energy sources. In 2023, Microsoft’s emissions increased by 29 percent compared to 2020, which was mainly due to the construction of modern data centers.
Three Mile Island Nuclear Power has two reactors. Reactor Two was the infamous site of a partial core meltdown in 1979 and has been idle since. But Reactor One operated without incident until 2019, when it was shut down for financial reasons—largely due to competition from gas- and wind-powered electricity. Kotek says there are relatively few idle reactors that could also be brought back online fairly quickly, but many plant owners are interested in extending the operating licenses of their existing plants to try to ride the AI power wave.