Once upon a time, nuclear power was hailed as the energy of the future. But nuclear has been in decline for decades due to a variety of factors: reactors are expensive to build and maintain, the permitting process can be arduous, there still isn't a good solution for what to do with the spent fuel that’s its waste product. Additionally, high profile disasters like those at Chernobyl and Three Mile Island made some people hesitant to welcome nuclear projects into their communities.

Nevertheless, there has been a rush of new interest in nuclear — both in the United States and abroad. The U.S. and the U.K. just announced a new nuclear partnership, the Three Mile Island nuclear power plant is set to restart in a few years with help from Microsoft, and other big tech companies are plowing money into “new nuclear” startups.

“The single biggest driver in the paradigm shift we're seeing right now in the power sector comes down to data centers,” said Jackson Morris, director of state power sector policy at the Natural Resources Defense Council. “Load growth for electricity that we had already forecasted is now coming 10 years sooner and five times as fast because of data centers and these facilities largely being built by the big hyper scalers like Amazon, Google, Microsoft, etc.”

In the last few years, dozens of countries have pledged to triple nuclear capacity by 2050, and many of them are focused on what are called Small Modular Reactors or SMRs. Their proponents say they’d be cheaper and faster to build and cheaper to operate than the reactors we’ve had for decades. And they could be produced at scale in factories rather than custom-built on site.

“Small modular reactors are this new emerging technology,” said Morris. “They do have different characteristics that make them attractive for developers and for end users, but they still generate waste and they still have a significant public health and safety risk that needs to be managed by an independent, strong regulator.”

Additionally, while there are lots of companies working on developing SMRs, the technology is still in the development stage. 

“They exist on paper. None of them have been demonstrated, except for one in Russia and one in China at great expense,” said Allison Macfarlane, director of the School of Public Policy and Global Affairs at the University of British Columbia. She served as chairman of the U.S. Nuclear Regulatory Commission in the Obama administration.

Macfarlane said when it comes to SMRs in the United States, “The reactors don't exist, and as a result, we don't know if they're going to be cheaper, smaller, safer, you know, present less of a nuclear weapons proliferation risk, until you actually build these things, you have no idea about any of those.”

That’s where big tech is stepping in. Google is partnering with an SMR startup to get the tech online for its data centers, and Amazon is trying to get SMR tech out of the lab and onto the grid.

“Our goals in investing here are really to prove out that model help support a technology to scale,” said Patrick Leonard, global energy principal at Amazon Web Services. He said Amazon doesn’t want to necessarily develop the technology itself, rather it’s promising to buy whatever energy SMRs projects might produce in order to help projects get financing. 

“And then longer term, Amazon will be able to transition to that role where we're really buying the energy the same way you buy any other form of energy through a utility or another supplier from the grid.”

But all of this is going to take a long time. The Trump administration is promising to speed up permitting, but as Jackson Morris of the Natural Resources Defense Council points out, the energy demands from data centers are growing even faster.  

“Even the most bullish developers will acknowledge this is a 10-year solution for a 24-month, three-to-five-year problem,” he said. “That's why we have real questions about what role it will play in the Near to medium term, even as we're open to it potentially playing a role in the longer, kind of 10 to 15 year time horizon.”

And, in the meantime, skeptics of going all in on SMRs, including former nuclear commissioner Allison Macfarlane, say the money and effort being spent on this could be better used elsewhere.

“There are renewable technologies, wind, utility scale solar PV, that are far cheaper than nuclear will ever be, and they exist right now,” she said. 

And while the tech titans and other countries are still investing in those renewable options, those priorities have fallen way down the priority list for the federal government here in the U.S., while nuclear power is rising.