For five years, reactor one at Three Mile Island nuclear power station in Pennsylvania has lain dormant. Now, thanks to a deal with Microsoft, the reactor will start running again in 2028—this time to exclusively supply the tech firm with oodles of low-carbon electricity.
It’s all part of an ongoing flirtation between Big Tech and nuclear power. In March, Amazon Web Services agreed to buy a data center powered by Susquehanna nuclear power station in Pennsylvania. At an event at Carnegie Mellon University on September 18, Alphabet CEO Sundar Pichai mentioned small modular nuclear reactors as one potential source of energy for data centers. The links don’t stop there either: OpenAI CEO Sam Altman chairs the boards of nuclear startups Oklo and Helion Energy.
The AI boom has left technology companies scrambling for low-carbon sources of energy to power their data centers. The International Energy Agency estimates that electricity demand from AI, data centers, and crypto could more than double by 2026. Even its lowball estimates say that the added demand will be equivalent to all the electricity used in Sweden or—in the high-usage case—Germany.
This surge in energy demand is music to the ears of the nuclear power industry. Electricity demand in the US has been fairly flat for decades, but the sheer scale and intensity of the AI boom is changing that dynamic. One December 2023 report from a power industry consultancy declared the era of flat power demand over, thanks to growing demand from data centers and industrial facilities. The report forecasts that peak electricity demand in the US will grow by 38 gigawatts by 2028, roughly equivalent to 46 times the output of reactor one at Three Mile Island.
“AI is really taking off, and it’s garnering a lot of attention in the energy industry,” remarks John Kotek, senior vice president for policy development and public affairs at the Nuclear Energy Institute. He also points out the national security implications of AI, noting that it represents a field of competition between the US and global rivals, urging that lagging behind in AI due to insufficient power supply is a significant concern.
Nuclear power is deemed appealing by tech enterprises as it delivers continuous low-carbon electricity, unlike the intermittent nature of solar and wind power, which require energy storage solutions. By reactivating its first reactor, Microsoft will secure 835 megawatts of low-carbon power for 20 years, crucial to achieving its commitment to become carbon negative by 2030. The escalating energy demands from AI have led to a 29 percent surge in Microsoft’s emissions in 2023 compared to 2020, primarily due to new data center constructions.
Three Mile Island nuclear power station houses two reactors, with the second one having undergone a notorious partial meltdown in 1979 and has been dormant since. However, the first reactor operated seamlessly until its decommission in 2019 for economic reasons, due to competition from gas and wind power sources. According to Kotek, few idle reactors could be restarted swiftly, while many power plant owners are considering prolonging their operating licenses to meet the growing power demands from AI.
Power plant operators are motivated by governmental incentives such as those in the Inflation Reduction Act, which offers tax credits for electricity production at existing nuclear facilities. However, to fulfill the anticipated energy demand, Kotek emphasizes the need for constructing new reactors. The number of operational nuclear reactors in the US peaked at 112 in 1990, dropped to 92 by 2022, and the latest reactors at Vogtle power plant in Georgia took over 14 years to complete, costing more than double the anticipated budget.
“The US showed at Vogtle that we’re not very good at building plants,” says Todd Allen, chair of nuclear engineering and radiological sciences at University of Michigan. But Allen points out that China seems to build nuclear power plants much more quickly than the US, so speeding up is possible, and that if energy demand from data centers continues to grow, then building entirely new plants will increasingly look like an attractive option.
These potentially lengthy timescales are part of the reason why Microsoft is interested in small modular reactors, which should be quicker and cheaper to build. But tech firms have tended to emphasize searching for new sources of energy rather than improving the efficiency of their artificial intelligence operations, says Sasha Luccioni, AI and climate leader at Hugging Face, a company that develops tools for building applications using machine learning. “Regulation could be one way to incentivize [great efficiency], starting with mandatory reporting and transparency for companies providing AI tools and services,” she says.
At the Carnegie Mellon University event, Pichai said that work on improving the consumption side of AI’s energy usage was still in its “early phases.” “We are all inefficiently pretraining these models, absolutely,” he said, but added that inference—actually asking an AI model to perform a task—could become “dramatically more efficient over time.” Google’s emissions in 2023 were 48 percent higher than their 2019 baseline, primarily due to increases in data center energy consumption and supply chain emissions, putting Google’s goal to reach net zero emissions by 2030 increasingly under threat. “The energy demands of AI are rising right now,” says Luccioni, but the renewable or low-carbon energy to fuel AI isn’t keeping pace quickly enough.
For some, the prospect of the site of the US’s most notorious nuclear disaster being used to power the AI revolution might sit uneasily. But Allen points out that reactor one did not shut down because of operational issues. Restarting the reactor, he says, will mostly be a question of making sure it is still in good operating condition and that there are enough trained staff to run it smoothly.
