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Even if the technology works, the economics might not.
Nuclear fusion, sometimes breathlessly referred to as the “holy grail” of clean energy, capable of providing “near limitless” energy, might actually, finally be on the verge of working. And when that first prototype reactor turns on, the feverish headlines about harnessing the power of the sun and the stars here on Earth will at least be somewhat justified. Fusion is going to be a massive scientific achievement, but in a practical sense, it might not matter.
“We can make it work,” Egemen Kolemen, fusion expert and associate professor of mechanical and aerospace engineering at Princeton University, told me. “But at what price?”
Figuring out fusion is one thing, penciling out the economics another. There’s a nontrivial chance that fusion could become a scientific reality but remain too expensive to make a dent in the barriers to decarbonization.
How this plays out largely depends on what the grid looks like by the mid-2030s, when the leading fusion startups think we’ll see the first demonstration reactors come online. President Biden wants to fully decarbonize the electricity sector by 2035. And as ambitious — or, as many say, unrealistic — as that may be, how close we get and how we get there will determine what opportunities remain for fusion.
By the mid-2030s, the cost of building new fission reactors could come down significantly; if The Nuclear Company has its way, we’ll have built a 6 gigawatt fleet of standard nuclear plants by then. Or maybe small, modular reactors will finally prove out, squeezing much of the market space for fusion. And then there’s all the other emergent, grid-firming tech in various stages of development. Think long-duration battery storage, enhanced geothermal, and hydrogen for starters.
“Batteries go down in price, hydrogen goes down, you know, two orders of magnitude, whatever. And then you say, we’re okay, we don’t need an extra [energy] source,” Kolemen told me. “So we have to be very clear that that’s an option as well.”
Needless to say, investors know it’s a gamble. “This is venture, of course there’s a chance that it might not be economically feasible,” Gabriel Kra, managing director and co-founder at climate tech VC Prelude Ventures, told me. “That’s not a reason, in any case, not to try.” Prelude Ventures has invested in two fusion companies, Thea Energy and Xcimer Energy, while venture capitalists on the whole have poured $6.7 billion into fusion since 1992, according to the Fusion Industry Association, the vast majority of that in the past three years.
Many of these same venture firms are also placing big bets on other energy solutions that promise to provide many of the same benefits as fusion, such as Fervo’s enhanced geothermal tech, or Koloma’s artificial intelligence-powered geologic hydrogen detection system, or Form Energy’s long-duration iron-air batteries. But because none of these brand new technologies has yet achieved meaningful scale, creating simple price forecasts or cost curve models isn’t possible.
A refrain I heard a few times, however, is that no matter the energy mix of the future, fusion’s viability isn’t simply a matter of dollars and cents. “Even if fusion doesn’t get as cheap as solar or wind, or even if it doesn’t get as cheap as natural gas, there’s still a huge place for it in the grid,” Kra said.
Siting fusion reactors near dense urban areas, for example, could help solve one of the principal issues with renewables. “Even now, it’s becoming difficult to find sites for solar and wind, and we have a fraction of what we would need,” Jacob Schwartz, a staff research physicist at the Princeton Plasma Physics Laboratory, told me. “If you really want a lot of firm power that can be much physically denser than these other resources, you might really want to build fusion.” Siting fusion next to demand centers would also reduce the need to permit and build long transmission lines, which can take a decade or more if it happens at all.
Of course, fission reactors have these advantages too. A paper Schwartz and Kolemen published last year, modeling fusion’s place in various net-zero grid scenarios from 2036 to 2050, found that in most of them, fusion plants would be primarily displacing fission. That is, if they made sense at all. The authors (including Princeton energy systems professor and Heatmap contributor Jesse Jenkins) also found that if the price of competing technologies creates at least a moderate market opportunity for fusion, we could wind up with 100 gigawatts or more of fusion capacity, about the size of the current domestic fission fleet. But if other technologies outperform and drop significantly in price, it’s possible that no commercial fusion plants would get built in that timeframe.
Kra, however, disagrees with a core assumption of the paper — that the U.S. will actually meet our carbon-free energy targets. “I don’t want to be a doomer, but I don’t think we’re going to decarbonize the grid by 2035,” Kra told me. “I think the first fusion plant that comes online, maybe between 2035 and 2040, will be displacing a fossil source at that moment in time.”
Looked at that way, the calculus changes. Fusion could become just another player in the renewables mix, slotting in alongside a plethora of other emergent and established carbon-free technologies to supplant fossil fuels in an all-of-the-above march towards zero emissions. It would still need to be cost-effective, of course, but if it’s framed as a possible successor to fossil fuels as opposed to a rival of existing clean energy sources, that’s a much better sales pitch.
That said, it’s going to take more than just reaching cost-parity with fission for fusion to take off. If that’s all we do, Kolemen told me, “it will have the exact same result, which is that nothing is going to be built.”
And even if fusion doesn’t end up penciling out for the U.S. grid, it may still in other areas of the world with less abundant renewable energy resources and rapid load growth. Phil Larochelle, the leader of Breakthrough Energy Ventures fusion investment strategy, told me that it’s really not the West that stands to benefit the most.
“You’ve got the rest of the world — call it, 80% of the world's population — who are trying to live a life of prosperity, like we do here.” But raising standards of living around the world means a huge increase in energy consumption. “And so then the question is, can you just kind of sneak across the finish line with wind, solar, storage, transmission, geothermal, a bit of natural gas?” Larochelle asked. While he said it should be possible, it wouldn’t allow for the flourishing vision of the future that he hopes to see. “Sustainable abundance for all. That’s, I think, where fusion really shines,” he told me.
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The company, Nuclearn, aims to speed development and licensing processes with the help of a specially trained large language model.
You’d be hard-pressed to dream up a buzzier clean tech concept than an AI platform custom-designed for the nuclear industry. Yet Phoenix-based startup Nuclearn has been betting on the role of artificial intelligence in the booming nuclear sector since 2021 — predating the wide launch of ChatGPT and the Trump administration’s recent embrace of nuclear energy.
Now the funds are rolling in. The company announced today that it raised a $10.5 million Series A round led by the climate tech venture fund Blue Bear Capital. With this cash, Nuclearn plans to expand its repertoire of AI offerings, which spans everything from identifying and documenting faults in a reactor to project scheduling, engineering evaluations, and licensing and permitting for new or modified reactors.
To expedite these processes, the company has developed its own, nuclear-specific language model, built atop existing open source models and trained on public data from the Nuclear Regulatory Commission and other government agencies, Nuclearn’s cofounder and CFO, Jerrold Vincent, told me. This allows the model to pick up on “a lot of nuclear specifics, whether it’s the acronyms, vernacular, specific processes, even just sometimes the way [the nuclear industry] thinks about certain types of issues and the level of scrutiny they put on one thing versus another,” he explained.
By way of example, Vincent told me that one of the startup’s current customers is working on a licensing application and wanted to conduct some background research to identify potential gaps or areas where the NRC might raise additional questions. Every other time the company has pre-checked an application like this, Vincent said, it was a 400-hour process. Nuclearn helped reduce that timeline to less than a day.
It’s a deeply resonant win for Vincent and his cofounder, Bradley Fox, who are all too familiar with the inefficiencies of the industry themselves. Prior to founding Nuclearn, both worked in data science at the Palo Verde Nuclear Generating Station in Arizona, where employees spent thousands of hours every year on “a lot of documentation, a lot of paperwork, a lot of manual work,” Vincent told me.
Natural language processing had some very obvious applications for the nuclear industry. “Everything in nuclear is text. Everything’s written down,” Vincent said. So when some of the seminal research on novel deep learning models started coming out in 2017 and 2018, Vincent and Fox took note, exploring ways they could apply this to their own work. “Those were trends we jumped on very, very early, not because they were particularly fashionable at the time or because there was a lot of hype around it, but because that was the type of techniques we needed to be able to solve these problems,” Vincent told me. “That’s why we got into the language model space half a decade before ChatGPT.”
For the majority of jobs, such as working on permitting or license renewals, Nuclearn uses a software layer on top of its language model to coordinate various AI agents working on tasks linked to different data sets, such as analyzing design functions, safety protocols, or systems degradation over time. The software then integrates these various outputs to generate reports or summary analyses. On the operational side, the company has its own benchmarks to evaluate how its AI tools are performing on nuclear-specific tasks.
To date, the company has integrated its AI platform into the operations of more than 65 reactors both domestically and abroad, which Vincent told me represents a mix of standard commercial reactors and small modular reactors. As the market heats up, demand may well follow. With the Trump administration pushing to accelerate nuclear development, electricity demand rising, and tech giants prioritizing clean, firm power, it’s boom times for companies looking to build everything from conventional nuclear plants to small modular reactors, microreactors, and the long-elusive fusion reactor, each and every one of which will have to be licensed and permitted.
All this activity also means that the nuclear workforce is under strain, especially given that 25% set to retire in the coming decade. “We’ve had knowledge and workforce challenges for several years now, and now it’s getting exacerbated quite substantially from all the macro trends going on,” Vincent told me. Given this situation, he doesn’t anticipate that the adoption of AI tools will necessarily lead to layoffs. These days, he said, the industry is just wondering “how do we do the things we need to do to operate a nuclear power plant safely and efficiently with less people?”
With this new capital, the startup plans to scale its operations to encompass even more aspects of nuclear reactor management. One future use case Vincent anticipates is helping to automate the sourcing of unique, industry-specific parts. There are plants operating today, he told me, that rely on equipment from vendors that may be long out of business. Figuring out how and where to source equivalent components is the type of niche challenge he’s excited to take on.
“It just tends to be very manual, labor intensive, and very documentation heavy,” Vincent told me of the industry as a whole. Luckily, “those are all things that AI is very good at solving these days.”
On Tesla’s losses, Google’s storage push, and trans-Atlantic atomic consensus
Current conditions: Hurricane Kiko is soaking Hawaii and slashing the archipelago with giant waves • Nearly a foot of rain is forecast to fall on parts of Texas, risking flash floods • Dry, windy weather across broad swaths of South Africa is bringing “extremely high” fire risk.
China's clean-energy investments are paying green dividends. Ember
China’s clean energy boom is bringing a global decline in fossil fuel demand into sight amid declines in usage in the buildings, vehicles, and industries of the world’s second-largest economy, according to the think tank Ember’s latest China Energy Transition Review. The report, released Tuesday morning, found that exports of solar panels, batteries, electric vehicles, and heat pumps are soaring, particularly to emerging economies, making the possibility of developing nations making possible an “energy leapfrog” over the coal phase of growth. From 2015 to 2023, China’s end consumption of fossil fuels fell 1.7% across buildings, industry and transport, while electricity use as a replacement rose by 65%. In power generation, fossil output dropped 2% in the first half of 2025 compared to the same period last year, as wind and solar generation soared by 16% and 43%, respectively. Last year alone, Beijing invested $625 billion in clean energy, 31% of the global total.
“China is now the main engine of the global clean energy transition,” Muyi Yang, coordinating lead author of Ember’s 2025 analysis, said in a statement. “Policy and investment decisions made in China over the last two decades are fundamentally changing the basis of China’s own energy system, and enabling other countries to also move swiftly from fossil to clean.”
As Americans scramble to buy electric vehicles ahead of the expiration of the $7,500 consumer tax credit at the end of this month, fewer of those cars are Teslas. The preliminary August data Cox Automotive released on Monday showed the best month for EVs in U.S. history was the worst for Tesla ever recorded. EVs climbed to almost 10% of total car sales last month, but Tesla’s share fell to 38%, with 55,000 cars sold all month. That’s up just 3% compared to July and down 6% from the year prior, while the company’s total market share fell from just over 40% in July and 45% in the first half of the year. By contrast, Heatmap’s Matthew Zeitlin noted, Tesla commanded about 80% of U.S. EV sales in 2020.
Also on Tuesday, the company unveiled two new energy storage products that could boost its utility division. At the RE+ conference in Las Vegas, Tesla presented the Megapack 3, the latest generation of its utility-scale battery system, and the Megablock, which integrates the Megapack 3 with transformers and switchgear. Batteries were Tesla’s fastest growing business in the first quarter of this year, as Matthew reported in April, but the company feared that tariffs would affect the business. “The energy segment — which includes the company’s battery energy storage businesses for residences (Powerwall) and for utility-scale generation (Megapack) — has recently been a bright spot for the company, even as its car sales have leveled off and declined.”
Google inked a deal with the Salt River Project, the utility serving much of Arizona’s largest metropolis, to test the performance of long-duration energy storage projects. The first-of-a-kind research collaboration aims to “better understand the real-world performance of emerging non-lithium ion long duration energy storage technologies” in the Phoenix area, the power company said in a press release. Google will fund a portion of the costs and evaluate data on the pilot projects’ operational success. “We believe that long duration energy storage will play an essential role in meeting SRP’s sustainability goals and ensuring grid reliability,” Chico Hunter, the nonprofit Salt River Project’s manager of innovation and development, said in a statement.
As I reported in this newsletter in July, Google also backed the Italian carbon dioxide-based storage startup Energy Dome as the tech giant pushes to expand its portfolio of technologies to power its data centers 24/7.
The European Union has been a solid backer of fusion energy research. But the anti-nuclear trifecta of Germany, Austria, and Luxembourg has long thwarted bloc-wide efforts to bolster fission, which provides the bulk of the continent’s electricity. With Berlin finally joining Paris in backing traditional nuclear power, that blockade is no longer holding. The European Commission has proposed spending $11.5 billion on bolstering research in both fusion and fission, the trade publication NucNet reported Monday.
Meanwhile in the United States, where nuclear power remains broadly supported across the political spectrum, the biggest question is how quickly new reactors can come online. The data center industry has now called on the Nuclear Regulatory Commission to streamline licensing of new reactors to help meet its surging demand for electricity. In a letter to NRC Chair David Wright shared with E&E News, the Data Center Coalition, a trade group representing server farms, urged the agency to update its regulations to ensure quicker deployment of advanced reactors. “Increasingly, DCC members are forming strategic partnerships and committing to offtake agreements with utilities and nuclear technology developers, injecting new momentum into this strategic sector,” wrote Cy McNeill, the group’s director of federal affairs. “We are approaching the cusp of a truly revitalized nuclear sector.”
The push comes amid what Heatmap’s Katie Brigham called a “nuclear power dealmaking boom.”
Patagonia’s billionaire founder helped popularize the greenest trend in apparel — buying less of higher quality, longer-lasting clothing. Now the retailer is pushing to bring that same ethos to the food business. The company’s edible offerings of tinned fish and crackers designed for hiking is now expanding into baby foods, oils, and sauces, The New York Times reported in a new profile of the retailer. Fifty years from now, founder Yvon Chouinard told the newsletter, “I could see the food business being bigger than the apparel business.”
U.S. EV sales have been way up — just not for the domestic champion, which sank to its worst-ever market share in August.
Americans are rushing to buy electric vehicles ahead of the expiration of the $7,500 consumer tax credit at the end of this month.
And fewer of those cars are Teslas.
Preliminary data from Cox Automotive for August, first shared with Reuters, shows that the month was the best for EVs in U.S. history, with just over 146,000 units sold, comprising almost 10% of total car sales that month. At the same time, Tesla’s share of the EV market hit its lowest recorded level, down to a (still sizable) 38%.
Cox’s data puts Tesla sales at 55,000 for the month, which is up a little more than 3% from July but down over 6% from a year prior, while the company’s total market share fell from just over 40% in July and 45% in the first half of the year. In 2020, by contrast, Tesla’s share of U.S. EV sales was about 80%. Overall, Cox estimated that Tesla sales in the U.S. are down about 9% so far this year.
“The U.S. EV market is in a far more dynamic place than a few years ago,” Corey Cantor, the research director at the Zero Emission Transportation Association, told me in an email. “Most automakers now offer electric vehicle models in multiple segments. There are multiple electric vehicles available below the average price point of a new car at $48,000.”
Entering this new phase means that the EV market is getting less Tesla-centric, almost by definition. Morgan Stanley reported that electric vehicle sales were up 23% in August from a year ago, while overall car sales were up 7.5% — although even amidst this industry-wide growth, Tesla sales fell more than 3% year over year, while electric vehicle sales were up 42%.
Much of that EV market growth comes down to timing. “Early indications are that EV sales are in fact surging over the past two months, following the changes that will phase the credit out at the end of this month. We’ve seen record sales for EV models last month, such as the Honda Prologue,” Cantor said. This likely means some portion of these sales are being “pulled forward” from buyers trying to beat the deadline and these sales numbers will not persist through the rest of the year.
As Tesla’s stranglehold over the U.S. EV market may be weakening, so too is its hold on the international market. Thanks to CEO Elon Musk’s association with right wing politics in the U.S. and abroad, and to fierce competition from Chinese EV leader BYD, Tesla’s sales have fallen dramatically in Europe. Globally, BYD overtook Tesla in sales last year.
None of that seems to matter much to Tesla’s leadership, or to its shareholders. On Friday, the company’s board of directors put forward a new compensation plan for Musk that would boost his ownership of the company to around 25% and put him in line for a $1 trillion payday if he meets growth and performance targets over the next decade.
A Delaware court last year threw out an earlier Musk pay package, arguing that Musk was too close to the board of directors for them to objectively determine his pay in the interest of all the company’s shareholders. (He subsequently relocated Tesla’s official headquarters to Austin, Texas, explicitly to avoid Delaware jurisdiction.) Musk has said that he wants to own about 25% of the company, a significant upgrade from the roughly 15% he owns currently.
Tesla’s board said in a recent regulatory disclosure that Musk had “reiterated that, if he were to remain at Tesla, it was a critical consideration that he have at least a 25% voting interest in Tesla,” and that “Mr. Musk also raised the possibility that he may pursue other interests that may afford him greater influence if he did not receive such assurances.”
The board’s disclosure also confirmed that Musk sees the future of Tesla as going far beyond selling cars to people. The filing said that “through its discussions with Mr. Musk,” the special committee in charge of coming up with his compensation had “identified four core product lines that would drive Tesla’s future transformation”: Tesla’s vehicle fleet, automation (i.e. Full Self-Driving) software, its robotaxi product, and humanoid robots. Tesla’s robotaxi service is available on a select basis in Austin, with no date yet indicated for a wider rollout, while its humanoid robots — which Musk has said will one day make up 80% of the company’s value — are due to reach “scale production” next year, Musk said on a recent earnings call.
Tesla stock actually rose on the news of the proposed compensation package, likely because Tesla shareholders viewed it as a way to retain Musk and keep his attention on the company.
Longtime Tesla bull Adam Jonas, an analyst at Morgan Stanley, said in note to investors that the compensation deal now means that Musk “has an incentive to focus on Tesla more than ever.” Jonas also, like many Tesla bulls, sees its business of selling cars to people as just a small portion of its overall value — in his case, $76 a share, compared to his $410 a share price target or the roughly $346 a share price the stock was trading at on Monday afternoon.
Still, the company today is largely a pretty normal car company, at least according to its income statement. In the second quarter of its current fiscal year, some $16.6 billion of Tesla’s $22.5 billion in revenue came from cars, with $2.8 billion coming from its energy business and $3 billion coming from “services and other revenues.”
Declining market share in its biggest product line isn’t completely meaningless, even if many Tesla shareholders see a glorious future for the company beyond the automobile trade.
Looking ahead, Cantor said to expect the EV market to get even more diverse.
“Moving forward, we will continue to see automakers innovate in the EV space. Timelines may change and models will vary by automaker, but high-profile launches expected over the next year include the Rivian R2, a new version of the Chevrolet Bolt EV, as well as more affordable models by Lucid and Kia,” Cantor said in his email.
“While the 30D [consumer electric vehicle tax] credit’s phase out will have a real impact on sales the next quarter or two here in the U.S.,” he added, “the long-term trend of excitement and innovation continues to be in the launch of new electric vehicles.”