That Google is to power its data centers with electricity from seven small reactors it will build with the help of nuclear startup Kairos Power promises to add about 500 megawatts of carbon-free electricity at a time when energy demand for data centers and AI is surging.

According to Google, the new plants are to come on-line at the end of this decade. It's uncertain if the reactors would hook directly into Google's sites  or if they feed into the grid with Google claiming carbon-free power by virtue of its deal with Kairos.

Under the deal, Google becomes the third tech heavy player to try nuclear power to slake its thirst for electricity. In September, Microsoft said it would pay Constellation Energy to restart a reactor at Three Mile Island that had been closed since 2019. This year, Amazon said it would build a hyperscale data center and connect it directly to another nuclear plant in Pennsylvania.

If Kairos succeeds, it will simply revise a relatively new prediction: just last month the company said it will begin commercial operations in "the early 2030s," according to the U.S. Department of Energy's publication. Even if Kairos meets that revised target, it's locked into a race with fusion startups, many of which are looking to flip on commercial-scale power plants before 2035.

Kairos is one of a new breed of nuclear start-ups building so-called small-modular reactors as an attempt to lower the cost and speed the construction of nuclear power plants.

Most nuclear plants are huge complexes, producing 1,000 megawatts or more but take years to design and nearly a decade to construct. The latest fission reactors built in the United States, Vogtle Units 3 and 4 in Georgia, were completed in 2023 and 2024, respectively, ending a seven-year hiatus (the next newest reactor began operations in 2016). Yet they came in seven years late and $17 billion over budget.

SMR startups are trying to construct nuclear power plants faster and cheaper by using mass production techniques to bring down the cost and hasten up the construction. Kairos is attempting to push the technology a step further by cooling the reactor not with water but molten salts of lithium fluoride and beryllium fluoride. The Nuclear Regulatory Commission has approved plans of the startup for a demonstration reactor with 35 megawatts output, something which has remained elusive to Oklo, another SMR startup.

But while Kairos has only just been granted regulatory approval, there are many more obstacles it has yet to meet. To begin with, no commercial small-modular reactors have yet been brought online and as such, the economics have not yet been fully proven. And on top of that, Kairos's design uses molten salt instead of decades of industry experience with water-cooled reactors.

But Kairos's greatest challenge might have nothing to do with technology. After all, 56% of Americans say they favor nuclear power, according to both Pew Research, 44% still oppose. The number opposed might go up if reactor sites are selected; the Pew study only asked whether people thought the U.S. should expand nuclear power generally and not in their backyards. Further, even with support for nuclear power close to a recent high, many, much more than the percent supporting nuclear power, support wind and solar, both technologies that are available today and cost much less than new nuclear power plants.