Microsoft uses Three Mile Island nuclear power plant to power AI

The data centers that train the large language models behind AI consume unimaginable amounts of energy, and the stakes are high for big tech companies to ensure they have enough power to power those plants. That’s why Microsoft is now throwing its weight behind nuclear power.

The tech giant on Friday signed a major deal with nuclear power operator Constellation Energy to buy electricity for its data centers from the utility’s Three Mile Island Unit 1 nuclear power plant.

The plant is located next to TMI-Unit 2, which suffered an infamous meltdown in 1979. Unit 1 was closed in 2019 as demand for nuclear power declined amid competition from cheaper alternative energy sources such as natural gas, solar and wind.

Constellation said it plans to spend $1.6 billion to reactivate the Unit 1 plant by 2028, subject to regulatory approval.

Financial terms of the deal were not disclosed. Microsoft has agreed to buy all of the reactor’s power over the next 20 years, a Constellation spokesperson told TechCrunch. Once restored, the reactor promises to have 835 megawatts of power.

The new plant will also be renamed the Crane Clean Energy Center (CCEC) in honor of former Constellation CEO Chris Crane, who died in April. The plant is expected to create 3,400 direct and indirect jobs, add $16 billion to Pennsylvania’s GDP and generate more than $3 billion in state and federal taxes, according to an economic report commissioned by the Pennsylvania Building & Construction Trades Council.

“Powering industries critical to our nation’s global economic and technological competitiveness, including data centers, requires massive amounts of energy that is carbon-free and reliable around the clock, and nuclear is the only energy source that can consistently deliver on that promise,” Joe Dominguez, Constellation’s president and CEO, said in a statement.

Microsoft did not immediately respond to a request for comment.

Microsoft isn’t the only tech company turning to nuclear energy to power AI data centers. Sam Altman, CEO of OpenAI, has called for an energy breakthrough in the form of nuclear power, and Amazon in March bought a nuclear-powered data center in Pennsylvania for $650 million.

Microsoft, Amazon and Alphabet have all said they plan to run their data centers entirely on green energy. Microsoft aims to do so by 2030, but the company admitted in May that its push into artificial intelligence was putting that goal at risk.

In June, Bloomberg reported that upcoming data centers by major tech companies promise to use a combined 508 terawatt-hours of electricity per year if they run continuously. That would be more than all the electricity produced in Australia in a year.

Demand for clean electricity to power not only data centers but electric vehicles, factories and other devices has sparked a renaissance of sorts around nuclear power. Investors are increasingly bullish on fusion startups, which have raised $7.1 billion so far, because they represent a cleaner, more efficient future for nuclear power. They use hydrogen as fuel, while nuclear power plants and their fission process rely on hard-to-find elements like uranium and plutonium.