Venture capitalists in Silicon Valley and other tech hubs are investing money in nuclear energy for the first time in history. That’s changing its trajectory and pace of innovation.

“There’s not been a resurgence of nuclear power, ever, since its heyday in the late 1970s,” Ray Rothrock, a longtime venture capitalist who has personal investments in 10 nuclear startups, told CNBC.

Now, that’s changing. “I have never seen this kind of investment before. Ever.”  

Jacob DeWitte, CEO of micro-reactor startup Oklo, says the landscape has changed dramatically since he started raising money in 2014, when he was a part of the Y Combinator startup incubator.

“More investors are interested, more investors are excited by the space, and they’re getting smarter to do the diligence and know what to do here — which is good,” DeWitte told CNBC.

This surge of private investment will be a positive for the industry, agrees John Parsons, an economist and lecturer at MIT.

“I think having fresh perspectives is really good,” Parsons told CNBC. Nuclear energy is “a very complex science, and it’s been supported by the federal government and at these national labs. And so that’s a very small circle of people. And when you broaden that circle, you get a lot of new minds, different thinking, a variety of experiments.”

In any industry, there can be a “groupthink” or “narrowness” in the way things are done over time, Parsons said. With private investment in the space, “there will be out-of-the-box thinking,” he said. “Maybe that out-of-the-box thinking doesn’t produce anything useful. Maybe it turns out that the old designs are the best. But I think it’s really wonderful to have the variety of takes.”

Not everyone is so optimistic that the recent influx of venture dollars will lead to progress.

“Investors have often invested in stupid things that didn’t work,” Naomi Oreskes, a professor of the history of science at Harvard University, told CNBC. “Because the reality is that in a 75-year history of this technology, it has never been profitable in a market-based system.” If investors are putting money into nuclear now, that’s because they think they can make money, and “I can only think they believe they will make money because they think that there’s a big opportunity to have the federal government pick up a big part of the tab,” Oreskes said.

From 2015 to 2021, total venture capital deal flow in the United States increased 54% in terms of deals closed and 294% by dollar value, according to data compiled by private capital market research firm Pitchbook for CNBC. In that same time, climate investing deal flow in the United States jumped by 214% in terms of volume and 1,348% by dollar value.

In the nuclear space, investment rose even faster — 325% by volume and 3,642% by dollar value, according to Pitchbook.

Some of the rapid pace of increase in investment in the nuclear sector is explained by its starting point — virtually zero.

“This is still pretty small compared to the private investments in renewables,” like wind and solar, for example, said David Schlissel, director of resource planning analysis at the Institute for Energy Economics and Financial Analysis, a market research firm.

The venture market slowed overall in 2022, and nuclear investment is no exception. Concerns about the war in Ukraine, inflation, a wave of layoffs and murmurs of a recession have made investors nervous in the public markets and private alike.

“At the beginning of the year, we were looking at a much different financial paradigm for nuclear startups seeking funding. Now, following a war, and inflationary related forces, the fundraising market is just not what it was earlier and that is challenging for everyone seeking funding and support, nuclear or otherwise,” Brett Rampal, a nuclear energy expert who evaluates investment opportunities and consults for nuclear startups, told CNBC.

More than $300 billion poured into the venture capital industry in 2021. Rothrock expects to see more like $160 billion in 2022.

“I’m sure that some funds that pull back may never come back,” Rothrock said. But most investors who are putting money into a nuclear company understands that it will not be a quick investment, Rothrock told CNBC. “Entrepreneurs and investors at the level we are talking for nuclear are playing the long game, they have to. These projects will take time to mature and to generate real cash flows.”

Also, the Inflation Reduction Act that President Joe Biden signed into law in August, which includes $369 billion in funding to help combat climate change, has given nuclear investors a very significant positive signal, Rampal told CNBC.

“The IRA investment and production tax credits are not nuclear specific credits, they’re clean energy credits that nuclear is now considered a part of, and that sends a real important message to people and investors that would consider this space,” Rampal said. Similarly important, the European Union voted in July to keep some specific uses of nuclear energy (and natural gas) in its taxonomy of sustainable sources of energy in some circumstances, according to Rampal.

The nuclear power industry in the United States launched as a government project after the U.S. built the first atomic bombs during World War II. In 1951, a nuclear reactor produced electricity for the first time in Idaho at the National Reactor Testing Station, which would become the Idaho National Laboratory.

In the 1960s and 1970s, large conglomerates constructed big nuclear power plants, and those projects often ran over budget. “As a consequence, most of the utilities that undertook nuclear projects suffered ratings downgrades—sometimes several downgrades—during the construction phase,” according to a 2011 report from the Congressional Budget Office. Also, the Three Mile Island accident in 1979 raised public fears about safety and put a damper on construction.

Nuclear power generation in the United States peaked in 2012 with 104 operating reactors, according to the U.S. Energy Information Administration.

However, in recent years, private investors and venture capitalists have been putting money into nuclear startups, driven by a newfound sense of urgency to respond to climate change, as nuclear energy releases no greenhouse gases. There’s also the allure of funding underdog companies with huge upside.

The venture capital model is based on big bets — venture capitalists spread their money across many companies. Most are expected to fail or maybe break even, but if one or two companies get enormous, they more than cover the cost of all those losses. This is the investing model that built Silicon Valley stalwarts like Apple, Google and Tesla.

Some venture capitalists are especially excited about fusion. It’s the type of nuclear energy that powers stars, and it generates no long-lasting radioactive waste — but so far, it’s proven fiendishly difficult to create a lasting fusion reaction on Earth and impossible to generate enough energy for commercial generation.

“It’s far better than nuclear fission,” investor Vinod Khosla told CNBC in October. “It’s far better than coal and fossil fuels for sure. But it’s not ready. And we need to get it ready and build it.”

Khosla isn’t the only one. The private fusion industry has seen almost $5 billion in investment, according to the Fusion Industry Association, and more than half of that has been since since the second quarter of 2021, Andrew Holland, CEO of the association, told CNBC.

Others are excited about new advances in nuclear fission, the more traditional type of nuclear power based on breaking atomic nuclei apart, like DCVC founder Zachary Bogue, who invested in micro-nuclear reactor company Oklo.

“Advanced nuclear fission is a quintessential deep-tech venture capital problem,” Bogue told CNBC in September. There is technical and regulatory risk, but if those problems are solved, “there are just massive-scale returns … all of those elements are a perfect recipe for venture capital.”

While these bets seem expensive and risky compared with venture capital’s recent focus on software and consumer tech, they’ll still bring a faster and more agile approach than the old-line nuclear industry.

Take micro-reactors.

“These are going to be very expensive at first. But the goal is to find something that is a product that’s much more flexible, can go on to the grid in many more different places and serve different functions, and go off grid also,” explained MIT’s Parsons.

Similarly, fusion startups say they will generate energy much faster than government research projects like ITER, which has already been in progress since 2007.

This quick-turn approach to investment is spurring experimentation. New generations of nuclear reactors will have different sizes, different coolants and different fuels, explained Matt Crozat, senior director of policy development at the Nuclear Energy Institute. Some reactors are being designed for companies or communities in isolated areas, for example. Others are being made to operate at high temperatures for industrial processes, Crozat told CNBC.

“It really is expanding the range of what nuclear can mean,” Crozat said. Many won’t succeed, but time and the market will figure out what’s needed and what’s possible, he said.

Because venture investors are hungry for returns, this also spurs nuclear startups to chase multiple revenue streams as they’re getting their big-bet technology up and running.

For example, Bill Gates‘ nuclear innovation company TerraPower is working on a demonstration of its advanced reactor in Wyoming in collaboration with the U.S. Department of Energy, but in the meantime is using its capacity to produce isotopes that are also used in medical research and treatments. Advanced nuclear company Kairos Power is developing the capacity to produce salt for molten salt reactors, both for itself and to sell to other companies.

But critics say venture capitalists are ignoring the troubled history of nuclear power as a business.

“Investors have forgotten or are ignoring the lessons from earlier generations of nuclear plants which cost 2 to 3 times as much to build and took years longer than was promised by the vendors,” Schlissel told CNBC. For instance, a project to put two new reactors on the Vogtle power plant in Georgia was originally estimated to be $14 billion and ended up costing more than $34 billion and taking six years longer to complete than expected, he said.

Harvard’s Oreskes says the nuclear industry is a “technology with a long history of broken promises,” and she is skeptical of the sudden investor interest.

“If you were my daughter, and you had a boyfriend that had made repeated promises to you over months, years, decades, constantly breaking them, I would say, ‘Do you really want to be with this guy?'”

She’s not categorically anti-nuclear, and supports the continued operation of nuclear power plants that already exist. But she’s particularly skeptical of fusion, which has been promised to be “just around the corner” for decades, and says this new round of investments in fusion “doesn’t pass the laugh test.”

Ultimately, the new crop of nuclear startups has to figure out how to create nuclear energy in a cost-competitive way, or nothing else matters, says Rothrock.

“More money means more startups and to me that means more shots on goal (improving odds of success),” he told CNBC.

“The issue in nuclear is economics. Plants are complicated and take a while to build. Some of these new startups are tackling those issues making them more simple and thus cheaper. No one will buy an expensive power plant, especially a nuclear plant. Economics drives it all.”