Tech companies are increasingly turning to nuclear power as a source of emissions-free electricity to support their growing artificial intelligence (AI) needs and other operations.

Microsoft, Google, and Amazon have all recently partnered with nuclear power plant operators and developers to help power their data centers. These data centers, which provide vital computing services for businesses, have seen a surge in demand due to the massive investments in AI, which requires significantly more power compared to traditional tech operations such as social media or streaming services.

Microsoft has made a deal with an energy company to revive the dormant Three Mile Island nuclear plant in Pennsylvania. Meanwhile, this week, Amazon and Google announced their focus on small modular reactors, a new nuclear technology. Although these reactors are not yet commercially available, experts believe they could be cheaper and faster to build than the large nuclear reactors constructed in the U.S. since the 1950s.

While tech companies have long invested in renewable energy like wind and solar, they are now shifting toward nuclear power, seeking a reliable energy source that operates around the clock without greenhouse gas emissions. Renewables like wind and solar are not always available unless paired with energy storage solutions. Major tech companies have committed to powering their operations entirely with emissions-free energy by 2030, but the AI boom has increased their energy needs.

“They want to expand in a sustainable way, and right now, nuclear seems to be the best solution,” said Aneesh Prabhu, Managing Director at S&P Global Ratings.

On Monday, Google announced an agreement to purchase nuclear energy from small modular reactors being developed by a start-up, Kairos Power, aiming to have them operational by 2030. Shortly after, Amazon revealed its investment in another start-up, X-Energy, which is also working on small modular reactors. Microsoft had already announced a partnership with Constellation Energy to revive the Three Mile Island reactor.

Prabhu noted that small modular reactors could cost around $1 billion each, and one day, they could potentially be built near data centers.

The tech industry isn’t alone in supporting nuclear energy. President Biden recently signed a bipartisan bill that aims to accelerate the development of nuclear projects. The Biden administration views nuclear power, which currently generates about 20% of the nation’s electricity, as key to reducing greenhouse gas emissions—a stark contrast to past opposition from some Democrats due to safety and environmental concerns.

Reviving the nuclear sector is essential for providing carbon-free energy to meet the growing demand from sectors like AI, data centers, manufacturing, and healthcare, according to Energy Secretary Jennifer Granholm.

The involvement of tech companies could breathe new life into the struggling nuclear industry. While the U.S. operates more nuclear reactors than any other country, only two have been built in recent decades. Both reactors, at the Vogtle plant in Georgia, were delayed by years and exceeded their budgets by billions of dollars. This, along with a failed project in South Carolina, had dampened hopes for a “nuclear renaissance.”

However, tech leaders believe this time will be different. Microsoft co-founder Bill Gates has personally invested over $1 billion in TerraPower, a start-up focused on developing smaller reactors, in collaboration with Warren Buffett’s utility company, PacifiCorp. The idea is to mass-produce small components for each unit, making them more affordable. Reactors could be added incrementally, allowing plants to scale up as needed.

“The key to making nuclear energy affordable is to build a lot of units and keep the design consistent,” said Rich Powell, head of the Clean Energy Buyers Association, which counts major tech companies among its members.

Nevertheless, nuclear energy skeptics argue that these promises overlook persistent issues, such as the high costs of new reactors, delays in construction, and the absence of a permanent storage solution for nuclear waste.

Since 1960, the U.S. has attempted to construct 250 nuclear reactors, but over half were canceled before producing any electricity, and none of the remaining projects were completed on time or within budget, according to Arnie Gundersen, chief engineer at the nonprofit Fairewinds Energy Education.

Despite these challenges, many tech and energy leaders believe nuclear power is essential, as renewable sources like wind, solar, and hydroelectric aren’t reliable enough to meet the increasing energy demands.

Electricity consumption has already been rising due to the adoption of electric vehicles, heat pumps, and air conditioners, and data centers are further accelerating this trend.

While data centers currently account for a small share of global energy use, that share is growing. Data centers, which require electricity to power and cool servers, are concentrated in certain regions like Northern Virginia, where they can strain local grids. The energy requirements are also increasing dramatically due to AI. While a typical server rack in a data center needs about 5 to 10 kilowatts, racks containing AI chips may demand over 100 kilowatts, according to Raul Martynek, CEO of DataBank.

Tech companies have been ramping up their investments to meet the growing energy demand from AI. The five largest tech firms, including Alphabet, Microsoft, and Amazon, collectively spent $59 billion on capital expenses in the last quarter, a 63% increase compared to the previous year. This spending is expected to continue.

Amazon recently spent $650 million to purchase a data center campus in Pennsylvania, which will be directly powered by an existing nuclear plant. In addition to its Three Mile Island deal, Microsoft has also partnered with Helion Energy, a Seattle-based start-up working to develop the world’s first nuclear fusion plant, expected to be operational by 2028.