Last Energy nabs $40M to realize vision of super-small nuclear reactors

A startup looking to build really small nuclear reactors just announced a big new funding round.

Last Energy, a Washington, D.C.–based next-generation nuclear company, announced that it closed a $40 million Series B funding round, a move that will add more financial and human capital to the reinvigorated nuclear sector.

The startup aims to eventually deploy thousands of its modular microreactors, though to date it has not brought any online. The first reactor might appear in Europe as soon as 2026, assuming Last Energy manages to meet its extremely aggressive construction, financial, and regulatory timelines — not a common occurrence in the nuclear industry. Venture capital heavyweight Gigafund led the round, which closed early this year but was revealed only today. The startup has raised a total of $64 million since its 2019 founding.

Last Energy is part of a cohort of companies betting that small, replicable, and mass-produced reactors will overcome the economic challenges associated with building emissions-free baseload nuclear power — and restore the moribund U.S. nuclear industry to its former glory. But the microreactor dream has yet to be realized; few of these small modular reactors (SMRs) have been built worldwide. None have been completed in the U.S., though one design from long-in-the-tooth startup NuScale Power has gotten regulatory approval.

The 20-megawatt size of Last Energy’s microreactor stands in stark contrast to that of a conventional nuclear reactor like the recently commissioned Vogtle units in Georgia, which each generate about 1,100 megawatts. A Last Energy microreactor, the size of about 75 shipping containers, might power a small factory, while a Vogtle unit can power a city.

Instead of the cathedral-style stick-built construction of modern large reactors, SMRs and microreactors are meant to be manufactured at scale in factories, transported to the site, and assembled on location. Rather than develop an advanced reactor design with exotic fuels — an approach taken by other SMR hopefuls, including the Bill Gates–backed TerraPower — Last Energy chose to scale down the well-established light-water reactor technology that powers America’s 94 existing nuclear reactors.

“We came to the conclusion that using the existing, off-the-shelf technology was the way to scale,” CEO Bret Kugelmass said in a 2022 interview with Canary Media. ​“We don’t innovate at all when it comes to the nuclear process or components — we do systems integration and business-model innovation.”

The startup claims that its microreactor is designed to be fabricated, transported, and built within 24 months, and is the right size to serve industrial clients. Under its business model, Last Energy aims to build, own, and operate its power plant at the customer’s site, avoiding the yearslong wait times to plug a new generation project into the power grid.

Like an independent power producer, Last Energy doesn’t sell power plants; instead, it sells electricity to customers through long-term power-purchase contracts.

“Data centers and heavy industry are trying to grapple with a very complex set of energy challenges, and Last Energy has seen them realize that micro-nuclear is the only capable solution,” said Kugelmass, who claims in today’s press release that the startup has inked commercial agreements for 80 units — with 39 of those units destined to serve power-hungry data center customers.

Last Energy isn’t the only microreactor company attracting venture funding. There are several other examples from this month alone: Aalo Atomics raised $27 million from 50Y, Valor Equity Partners, Harpoon Ventures, Crosscut, SNR, Alumni Ventures, Preston Werner, Earth Venture, Garage Capital, Wayfinder, Jeff Dean, and Nucleation Capital to scale up a 85-kilowatt design from the U.S. Department of Energy’s MARVEL program. While Deep Fission, a startup aiming to bury arrays of microreactors 1 mile underground, just raised $4 million led by 8VC, a venture firm founded by Joe Lonsdale.

These investors are joining the wave in public and private financing of nuclear energy that has swelled to $14 billion so far this year — double last year’s total, according to Axios. Investment in new fission technologies, such as microreactors, has increased tenfold from 2023.

Investors happen to be backing startups in a heavily subsidized market. Tens of billions of dollars from the Bipartisan Infrastructure Law, the U.S. DOE’s Loan Programs Office, and the Inflation Reduction Act support the development of a non-Russian supply of enriched uranium; the IRA also introduced a ridiculously generous $15-per-megawatt-hour production tax credit, meant to keep today’s existing nuclear fleet competitive with gas and renewables, as well as a similarly charitable investment tax credit to incentivize new plant construction.

The flood of funding comes as nuclear power enjoys the most public support it has had in years. Nuclear now has a favorable public opinion, with the majority of Americans supporting atomic energy and its record of safety and performance. And nuclear energy is one of the few topics that Democrat and Republican politicians have been able to agree on in recent memory.

Still, despite the rising financial, political, and public support, the U.S. nuclear industry remains frozen, plagued by a legacy of cost and timeline overruns for conventional reactors and regulatory challenges around new designs. It’s unclear when the country will get another nuclear reactor online — as of last year, the leading contender was an SMR project from NuScale, but that fell apart due to cost. In all likelihood, the next reactor to plug into the grid will be the mothballed Palisades nuclear plant in Michigan, which won government support for an unprecedented effort to recommission the plant by the end of next year.

For its part, Last Energy is not banking on the U.S. to lead the charge; it’s targeting industrial customers in Poland, Romania, and the U.K. for its initial sites, in the hopes that it will find a more favorable regulatory and financial environment.

Ryan McEntush of investment firm a16z suggests in an essay that ​“the success of nuclear power is much more about project management, financing, and policy than it is cutting-edge engineering or safety.”

That’s Last Energy’s philosophy too — and it’s going to need more money and more years to prove it’s the right one.