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Is international cooperation or technological development the answer to an apocalyptic threat?

Christopher Nolan’s film Oppenheimer is about the great military contest of the Second World War, but only in the background. It’s really about a clash of visions for a postwar world defined by the physicist J. Robert Oppenheimer’s work at Los Alamos and beyond. The great power unleashed by the bombs at Hiroshima and Nagasaki could be dwarfed by what knowledge of nuclear physics could produce in the coming years, risking a war more horrifying than the one that had just concluded.
Oppenheimer, and many of his fellow atomic scientists, would spend much of the postwar period arguing for international cooperation, scientific openness, and nuclear restriction. But there was another cadre of scientists, exemplified by a former colleague turned rival, Edward Teller, that sought to answer the threat of nuclear annihilation with new technology — including even bigger bombs.
As the urgency of the nuclear question declined with the end of the Cold War, the scientific community took up a new threat to global civilization: climate change. While the conflict mapped out in Oppenheimer was over nuclear weapons, the clash of visions, which ended up burying Oppenheimer and elevating Teller, also maps out to the great debate over global warming: Should we reach international agreements to cooperatively reduce carbon emissions or should we throw our — and specifically America’s — great resources into a headlong rush of technological development? Should we massively overhaul our energy system or make the sun a little less bright?
Oppenheimer’s dream of international cooperation to prevent a nuclear arms race was born even before the Manhattan Project culminated with the Trinity test. Oppenheimer and Danish physicist Niels Bohr “believed that an agreement between the wartime allies based upon the sharing of information, including the existence of the Manhattan Project, could prevent the surfacing of a nuclear-armed world,” writes Marco Borghi in a Wilson Institute working paper.
Oppenheimer even suggested that the Soviets be informed of the Manhattan Project’s efforts and, according to Martin Sherwin and Kai Bird’s American Prometheus, had “assumed that such forthright discussions were taking place at that very moment” at the conference in Potsdam where, Oppenheimer “was later appalled to learn” that Harry Truman had only vaguely mentioned the bomb to Joseph Stalin, scotching the first opportunity for international nuclear cooperation.
Oppenheimer continued to take up the cause of international cooperation, working as the lead advisor for Dean Acheson and David Lilienthal on their 1946 nuclear control proposal, which would never get accepted by the United Nations and, namely, the Soviet Union after it was amended by Truman’s appointed U.N. representative Bernard Baruch to be more favorable to the United States.
In view of the next 50 years of nuclear history — further proliferation, the development of thermonuclear weapons that could be mounted on missiles that were likely impossible to shoot down — the proposals Oppenheimer developed seem utopian: The U.N. would "bring under its complete control world supplies of uranium and thorium," including all mining, and would control all nuclear reactors. This scheme would also make the construction of new weapons impossible, lest other nations build their own.
By the end of 1946, the Baruch proposal had died along with any prospect of international control of nuclear power, all the while the Soviets were working intensely to disrupt America’s nuclear monopoly — with the help of information ferried out of Los Alamos — by successfully testing a weapon before the end of the decade.
With the failure of international arms control and the beginning of the arms race, Oppenheimer’s vision of a post-Trinity world would come to shambles. For Teller, however, it was a great opportunity.
While Oppenheimer planned to stave off nuclear annihilation through international cooperation, Teller was trying to build a bigger deterrent.
Since the early stages of the Manhattan Project, Teller had been dreaming of a fusion weapon many times more powerful than the first atomic bombs, what was then called the “Super.” When the atomic bomb was completed, he would again push for the creation of a thermonuclear bomb, but the efforts stalled thanks to technical and theoretical issues with Teller’s proposed design.
Nolan captures Teller’s early comprehension of just how powerful nuclear weapons can be. In a scene that’s pulled straight from accounts of the Trinity blast, most of the scientists who view the test are either in bunkers wearing welding goggles or following instructions to lie down, facing away from the blast. Not so for Teller. He lathers sunscreen on his face, straps on a pair of dark goggles, and views the explosion straight on, even pursing his lips as the explosion lights up the desert night brighter than the sun.
And it was that power — the sun’s — that Teller wanted to harness in pursuit of his “Super,” where a bomb’s power would be derived from fusing together hydrogen atoms, creating helium — and a great deal of energy. It would even use a fission bomb to help ignite the process.
Oppenheimer and several scientific luminaries, including Manhattan Project scientists Enrico Fermi and Isidor Rabi, opposed the bomb, issuing in their official report on their positions advising the Atomic Energy Commission in 1949 statements that the hydrogen bomb was infeasible, strategically useless, and potentially a weapon of “genocide.”
But by 1950, thanks in part to Teller and the advocacy of Lewis Strauss, a financier turned government official and the approximate villain of Nolan’s film, Harry Truman would sign off on a hydrogen bomb project, resulting in the 1952 “Ivy Mike” test where a bomb using a design from Teller and mathematician Stan Ulam would vaporize the Pacific Island Elugelab with a blast about 700 times more powerful than the one that destroyed Hiroshima.
The success of the project re-ignited doubts around Oppenheimer’s well-known left-wing political associations in the years before the war and, thanks to scheming by Strauss, he was denied a renewed security clearance.
While several Manhattan Project scientists testified on his behalf, Teller did not, saying, “I thoroughly disagreed with him in numerous issues and his actions frankly appeared to me confused and complicated.”
It was the end of Oppenheimer’s public career. The New Deal Democrat had been eclipsed by Teller, who would become the scientific avatar of the Reagan Republicans.
For the next few decades, Teller would stay close to politicians, the military, and the media, exercising a great deal of influence over arms policy for several decades from the Lawrence Livermore National Laboratory, which he helped found, and his academic perch at the University of California.
He pooh-poohed the dangers of radiation, supported the building of more and bigger bombs that could be delivered by longer and longer range missiles, and opposed prohibitions on testing. When Dwight Eisenhower was considering a negotiated nuclear test ban, Teller faced off against future Nobel laureate and Manhattan Project alumnus Hans Bethe over whether nuclear tests could be hidden from detection by conducting them underground in a massive hole; the eventual 1963 test ban treaty would exempt underground testing.
As the Cold War settled into a nuclear standoff with both the United States and the Soviet Union possessing enough missiles and nuclear weapons to wipe out the other, Teller didn’t look to treaties, limitations, and cooperation to solve the problem of nuclear brinksmanship, but instead to space: He wanted to neutralize the threat of a Soviet first strike using x-ray lasers from space powered by nuclear explosions (he was again opposed by Bethe and the x-ray lasers never came to fruition).
He also notoriously dreamed up Project Plowshare, the civilian nuclear project which would get close to nuking out a new harbor in Northern Alaska and actually did attempt to extract gas in New Mexico and Colorado using nuclear explosions.
Yet, in perhaps the strangest turn of all, Teller also became something of a key figure in the history of climate change research, both in his relatively early awareness of the problem and the conceptual gigantism he brought to proposing to solve it.
While publicly skeptical of climate change later in his life, Teller was starting to think about climate change, decades before James Hansen’s seminal 1988 Congressional testimony.
The researcher and climate litigator Benajmin Franta made the startling archival discovery that Teller had given a speech at an oil industry event in 1959 where he warned “energy resources will run short as we use more and more of the fossil fuels,” and, after explaining the greenhouse effect, he said that “it has been calculated that a temperature rise corresponding to a 10 percent increase in carbon dioxide will be sufficient to melt the icecap and submerge New York … I think that this chemical contamination is more serious than most people tend to believe.”
Teller was also engaged with issues around energy and other “peaceful” uses of nuclear power. In response to concerns about the dangers of nuclear reactors, he in the 1960s began advocating putting them underground, and by the early 1990s proposed running said underground nuclear reactors automatically in order to avoid the human error he blamed for the disasters at Chernobyl and Three Mile Island.
While Teller was always happy to find some collaborators to almost throw off an ingenious-if-extreme solution to a problem, there is a strain of “Tellerism,” both institutionally and conceptually, that persists to this day in climate science and energy policy.
Nuclear science and climate science had long been intertwined, Stanford historian Paul Edwards writes, including that the “earliest global climate models relied on numerical methods very similar to those developed by nuclear weapons designers for solving the fluid dynamics equations needed to analyze shock waves produced in nuclear explosions.”
Where Teller comes in is in the role that Lawrence Livermore played in both its energy research and climate modeling. “With the Cold War over and research on nuclear weapons in decline, the national laboratories faced a quandary: What would justify their continued existence?” Edwards writes. The answer in many cases would be climate change, due to these labs’ ample collection of computing power, “expertise in numerical modeling of fluid dynamics, and their skills in managing very large data sets.”
One of those labs was Livermore, the institution founded by Teller, a leading center of climate and energy modeling and research since the late 1980s. “[Teller] was very enthusiastic about weather control,” early climate modeler Cecil “Chuck” Leith told Edwards in an oral history.
The Department of Energy writ large, which inherited much of the responsibilities of the Atomic Energy Commission, is now one of the lead agencies on climate change policy and energy research.
Which brings us to fusion.
It was Teller’s Lawrence Livermore National Laboratory that earlier this year successfully got more power out of a controlled fusion reaction than it put in — and it was Energy Secretary Jennifer Granholm who announced it, calling it the “holy grail” of clean energy development.
Teller’s journey with fusion is familiar to its history: early cautious optimism followed by a realization that it would likely not be achieved soon. As early as 1958, he said in a speech that he had been discussing “controlled fusion” at Los Alamos and that “thermonuclear energy generation is possible,” although he admitted that “the problem is not quite easy” and by 1987 had given up on seeing it realized during his lifetime.
Still, what controlled fusion we do have at Livermore’s National Ignition Facility owes something to Teller and the technology he pioneered in the hydrogen bomb, according to physicist NJ Fisch.
While fusion is one infamous technological fix for the problem of clean and cheap energy production, Teller and the Livermore cadres were also a major influence on the development of solar geoengineering, the idea that global warming could be averted not by reducing the emissions of greenhouse gas into the atmosphere, but by making the sun less intense.
In a mildly trolling column for the Wall Street Journal in January 1998, Teller professed agnosticism on climate change (despite giving that speech to oil executives three decades prior) but proposed an alternative policy that would be “far less burdensome than even a system of market-allocated emissions permits”: solar geoengineering with “fine particles.”
The op-ed placed in the conservative pages of the Wall Street Journal was almost certainly an effort to oppose the recently signed Kyoto Protocol, but the ideas have persisted among thinkers and scientists whose engagement with environmental issues went far beyond their own opinion about Al Gore and by extension the environmental movement as a whole (Teller’s feelings about both were negative).
But his proposal would be familiar to the climate debates of today: particle emissions that would scatter sunlight and thus lower atmospheric temperatures. If climate change had to be addressed, Teller argued, “let us play to our uniquely American strengths in innovation and technology to offset any global warming by the least costly means possible.”
A paper he wrote with two colleagues that was an early call for spraying sulfates in the stratosphere also proposed “deploying electrically-conducting sheeting, either in the stratosphere or in low Earth orbit.” These were “literally diaphanous shattering screens,” that could scatter enough sunlight in order to reduce global warming — one calculation Teller made concludes that 46 million square miles, or about 1 percent of the surface area of the Earth, of these screens would be necessary.
The climate scientist and Livermore alumnus Ken Caldeira has attributed his own initial interest in solar geoengineering to Lowell Wood, a Livermore researcher and Teller protégé. While often seen as a centrist or even a right wing idea in order to avoid the more restrictionist policies on carbon emissions, solar geoengineering has sparked some interest on the left, including in socialist science fiction author Kim Stanley Robinson’s The Ministry for the Future, which envisions India unilaterally pumping sulfates into the atmosphere in response to a devastating heat wave.
The White House even quietly released a congressionally-mandated report on solar geoengineering earlier this spring, outlining avenues for further research.
While the more than 30 years since the creation of the Intergovernmental Panel on Climate Change and the beginnings of Kyoto Protocol have emphasized international cooperation on both science and policymaking through agreed upon goals in emissions reductions, the technological temptation is always present.
And here we can perhaps see that the split between the moralized scientists and their pleas for addressing the problems of the arms race through scientific openness and international cooperation and those of the hawkish technicians, who wanted to press the United States’ technical advantage in order to win the nuclear standoff and ultimately the Cold War through deterrence.
With the IPCC and the United Nations Climate Conference, through which emerged the Kyoto Protocol and the Paris Agreement, we see a version of what the postwar scientists wanted applied to the problem of climate change. Nations come together and agree on targets for controlling something that may benefit any one of them but risks global calamity. The process is informed by scientists working with substantial resources across national borders who play a major role in formulating and verifying the policy mechanisms used to achieve these goals.
But for almost as long as climate change has been an issue of international concern, the Tellerian path has been tempting. While Teller’s dreams of massive sun-scattering sheets, nuclear earth engineering, and automated underground reactors are unlikely to be realized soon, if at all, you can be sure there are scientists and engineers looking straight into the light. And they may one day drag us into it, whether we want to or not.
Editor’s note: An earlier version of this article misstated the name of a climate modeler. It’s been corrected. We regret the error.
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With wars going on in Ukraine and the Middle East, margins for fuel producers have gotten “insane.”
It’s never been a better time to turn oil into gasoline and diesel, and the United States refining industry is processing every drop it can.
America’s refineries are currently running at over 97% utilization, up slightly from the week prior, according to the Energy Information Administration, and at their highest rate since 2018. In the Gulf Coast refining complex specifically, refining capacity has been above 95% for 19 straight weeks, well surpassing the previous record of 15 weeks in 2022, according to Gulf Oil advisor Tom Kloza.
Meanwhile, refiners are putting off whatever maintenance they can. But refineries may have to undertake the large-scale, prescheduled “turnaround” operations that happen in the fall, and can take facilities offline for months.
The reason? It pays to wait. The “crack spread” — which measures the margin of refining three barrels of oil into two barrels of gasoline and one of diesel — sits at over $72.
“This is historically unprecedented,” Kloza told me, referring to both the continuously high levels of utilization for American refiners and the margins they’re receiving for running so continuously. “It’s insane.”
The insanity is the result of not one but two overlapping crises in the global fossil fuel industry. And while one (the protracted closure of the Strait of Hormuz) is in superposition between deterioration and resolution, the other (the relentless Ukrainian drone attacks on Russian refineries) shows no sign of letting up. Both crises contribute to the increasing unavailability of refined products like gasoline, jet fuel, and diesel, the scarcity of which has sent prices soaring.
Russia has banned diesel exports at least through September, leaving a hole that can be filled, at least in part, by American exports to the rest of the world. Diesel exports stand at around 1.8 million barrels per day, up from around 1.2 million a year ago.
One major refinery in New Brunswick, Canada that helps supply the Northeastern U.S. — which relies on diesel as a heating fuel in winter — is due to shut down for maintenance for over two months starting in September. Other refineries, however, have “basically every incentive right now to defer maintenance as long as they can,” considering the high profits they can get, Patrick DeHaan, head of petroleum analysis at GasBuddy, told me.
While refineries are designed to run up to (and maybe even slightly above) 100% utilization, “occasionally when you do run really hard, there can be some issues that come up from time to time,” DeHaan said. “Not all maintenance can be pushed.”
Even if U.S. refineries are operating as, uh, well-oiled machines, there’s another risk at this time of year beside mechanical issues: hurricanes.
While meteorologists expect this to be a below average hurricane season due to the above average El Niño stalking the Pacific, big storms can still knock out refining capacity on the Gulf Coast, where around half of the U.S. refining industry is located.
“If there’s a hurricane, they’re going to have to throttle back, and that will push the prices right up even more,” DeHaan said. A “perfect storm,” he said, could send those crack spreads up by another $20 to $30 a barrel. And yet he also noted that “it’s looking less and less likely that we’re going to see a perfect storm. El Niño is doing a great job mitigating risk for us.”
Even without adding a hurricane to the mix, fuel prices are high enough for anyone who uses diesel or heating oil — including truckers, farmers, and, eventually, New Englanders — to constitute a predicament.
“What we’re seeing now is extraordinarily rare to see,” DeHaan said, referring to the high level of output from U.S. refineries.
Nationwide, average diesel prices are $5.62 a gallon, according to AAA, up from $5.30 a month ago and $3.71 a year ago. In California, the number one agricultural exporter among the 50 states, diesel is $7.21 a gallon, hitting farmers (and eventually consumers) hard, as grapefruit, peaches, plums, apricots, avocadoes, tomatoes, cucumbers, apples, and figs (to name just a portion of the state’s bounty) are harvested in August and September.
The high level of exports has helped drive down inventories of distillate fuel, which are at their lowest level for this time of year since the EIA started keeping records in 1982.
The tightness of the market means that refineries are likely to be pushed near their limit. If any one goes off line — whether for maintenance or weather or anything else — it will likely mean a windfall for everyone else who can stay online.
On rare earth recycling, Africa’s solar boom, and Thailand’s LNG addiction
Current conditions: Tropical Storm Dolly formed in the Atlantic and is heading toward the Caribbean, threatening the Lesser Antilles with heavy rains and winds • Temperatures topped 110 degrees Fahrenheit in Las Vegas as the heat heads east to the Mississippi Valley • In Nepal, survivors of the catastrophic flood near the border with Tibet are swimming in debris-laden waters to fish out fuel cans as supplies run short.
Earlier this month, the Trump administration brokered yet another deal to pay a developer to, as Heatmap’s Robinson Meyer put it bluntly, “not build wind farms.” The German energy giant RWE took the $1.2 billion deal to kill off three already-stalled projects in New York and New Jersey. Turns out the bulk of that will go to a billionaire who owns a mansion on a private island in Florida near President Donald Trump’s Mar-a-Lago estate, and who personally donated nearly $1 million to the president’s inaugural committee. On Thursday, The Washington Post reported that the roughly $900 million from the settlement that RWE pledged to invest into liquified natural gas would go to a facility under construction by the company founded and run by Michael Dorrell, an Australian native with U.S. citizenship who has boasted of hobnobbing with his neighbor, the president. The White House said it had nothing to do with RWE’s decision to invest in the project, and called the newspaper’s story “a brazen attempt to insinuate a conflict-of-interest that does not exist.” But Representative Jared Huffman of California, the top Democrat on the House Natural Resources Committee, said “fake ‘settlements’” that “were already an insane waste of taxpayer funds and a ridiculous charade that seems to be blatantly illegal” now also carry “the stench of corruption.”
Cue the record scratch: We’ve got a narrative violation. A utility in the industrial Midwest portion of PJM Interconnection, the nation’s largest and most infamously stressed grid system, says that all the money it’s making off data centers will justify lowering the price of electricity for everyone else. Fort Wayne-based Indiana Michigan Power asked state regulators to reduce the base rate by enough to shave roughly $100 off annual bills. If the savings apply to the average customer using 1,000 kilowatts a month, the total combined savings in 2027 could come out to $59 million, according to The Journal Gazette, a family-owned newspaper published six days a week in Indiana’s second-largest city. The utility said it expects the Indiana Utility Regulatory Commission to decide on its proposed plan next June, meaning savings would kick in during the summer. The utility also asked to freeze rates at a lower amount for three consecutive years as part of what it called “one of the nation’s largest base rate reduction plans,” which it said was “made possible thanks to load growth and increased revenue from large customers including data centers.”
Since 2021, electricity prices statewide in Indiana spiked by more than 30%, according to data from Heatmap and the Massachusetts Institute of Technology’s Electricity Price Hub. But Indiana Michigan Power’s prices hiked by less than half the statewide average in that same period. When bills went up nearly 7% statewide last year, customers in the northeastern Indiana region that the utility serves saw a nearly 2% drop. All of which is to say: This particular case may not be as indicative of a potential trend as many might hope.
A pair of back-to-back funding deals on Thursday show just how much investors have warmed to geothermal and critical minerals, two domestic industries that — until recently — had spent decades either stagnant or in decline. Quaise Energy, the geothermal startup developing technology to drill to new depths in pursuit of super-hot rocks, just raised $180 million in its Series B. That includes a $35 million investment from Nabors Industries, owner and operator of one of the world’s largest fleets of drilling rigs. The money brings the Houston-based startup’s total fundraising to date to $280 million. “We are unlocking the most powerful clean energy source on Earth, and the Series B signals deep conviction across a wide range of investors,” Quaise CEO Carlos Araque said in a statement.
Meanwhile, metals recycler Cyclic Materials raised $75 million in a strategic financing round, bringing its total equity funding to date to $237 million. The latest funding was led by accounts advised by T. Rowe Price Associate, which had previously invested in the startup last year. The company’s first commercial facility in Arizona is expected to come online this year, and the funding will support the “advancement” of an integrated rare earths campus in South Carolina. “Our continued investment reflects our confidence in the company’s ability to scale domestic rare earth recycling and production infrastructure for use across critical U.S. industries and technologies,” Vineet Khanna, an investment analyst at T. Rowe Price, said in a press release.
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Even before the world outside feels like it’s burning, big chunks of the real-life human economy just stop churning. It seems self evident enough to be worthy of a rhyming truism (forgive me, I’m a recent recruit to the corny dad club). What’s alarming is that it’s starting to show up in data. A new Barclays survey of British businesses and consumers found that this year’s heat waves kept shoppers at bay, construction crews idled, and farmhands still. Temperatures above 77.2 degrees Fahrenheit were deemed too hot for shopping. Shave off just 2 degrees and Britons no longer wanted to commute. The construction and farming sectors took what Bloomberg called a “particularly hard hit” this summer when temperatures surpassed 100 degrees in the United Kingdom. But the newswire noted that the “intense heat also laid bare the extent to which much of Britain’s critical infrastructure is unprepared for rapidly rising temperatures, as schools, hospitals and public transport suffered under the strain.” As such, 60% of businesses reported that they are “now investing in or plan to invest in technologies to help them adapt to extreme heat.”

Exactly one year ago, I told you about new data showing that Africa’s purchases of Chinese solar panels had skyrocketed by 60%, with 20 countries setting new import records. Sierra Leone alone brought in enough panels to match more than 60% of its entire 2023 electrical output. What wasn’t clear is whether the equipment was going to warehouses or actually being deployed. Now Ember, the clean energy research firm behind last year’s analysis, is out with new numbers quantifying Africa’s solar boom. The continent installed record capacity of 17 gigawatts in 2026 so far, up 45% year-over-year. Chinese exports of solar panels to Africa soared in the 12 months leading up to June. Ember’s new analysis found that, including the Middle East and Latin America, around 73% of Chinese imports have been installed, with an average six-month delay. Across Africa, roughly 100,000 panels were installed every day in the past year.
Of Africa’s 54 countries, 36 are on track to install record amounts of solar in 2026, and 19 are exceeding 100% growth compared to the same period last year. The Democratic Republic of the Congo saw a 544% spike. Zimbabwe’s solar sector soared by 282%. Egypt’s by 176%. For Zambia, it’s 117%. Not too far behind is Sierra Leone, at 97%.
Thailand is famously one of only a handful of modern nations never colonized by European empires. Some debate that distinction, since the kingdom once called Siam did, in fact, lose a lot of territory to French and British conquest. Today, however, Thailand is undeniably at the mercy of foreign energy powers. The country generates more than 60% of its electricity from natural gas, of which it produces little. Instead, it imports from Australia, Qatar, the U.S., Malaysia, and Oman. Maybe not for long. Bangkok has announced plans to shift away from gas and embrace renewables and nuclear power in the wake of the Iran War energy shock, Bloomberg reported. The country now aims to swap to producing 60% of its electricity from carbon-free sources in 25 years — more than double the previous goal.
The seed-stage startup is eyeing a Series A after successfully enriching lithium and hydrogen isotopes.
While most coverage of the buzzy fusion energy industry — including my own — tends to focus on the startups promising to build commercial reactors within the next decade, a whole host of supporting industries will also need to mature in order to make that long-held scientific dream a reality. Isotope production is one of the biggest. No matter a company’s technical approach to fusion, it likely demands hydrogen and lithium isotopes — the former to fuel reactors, and the latter to breed more of that fuel.
That’s where Marathon Fusion comes in. The San Francisco-based seed-stage startup is developing isotope separation technology for two key purposes: recycling tritium — an extremely rare hydrogen isotope — from reactor exhaust so it can be reused as fusion fuel, and enriching lithium-6, which is needed to breed new tritium. On Thursday, the company announced that it succeeded in using its plasma centrifuge technology to enrich lithium-6 and hydrogen isotopes in the lab. (It can’t yet test the tech on actual tritium, which is expensive, radioactive, and tightly regulated by the Nuclear Regulatory Commission, so Marathon is validating its separation physics using the non-radioactive proxies deuterium and protium.) Marathon now plans to raise a Series A based on the results.
“People have wondered for a very long time when fusion is going to come, and everyone’s waiting on the big scientific announcements,” Marathon’s CEO Kyle Schiller told me. But while the industry waits for those breakthroughs, he argued, it’s high time to start commercializing the infrastructure fusion will need to become an actual commercial industry. “Ultimately, what we’re doing is reactor agnostic. Everyone’s going to need it.”
In the near term at least, most fusion companies plan to use deuterium-tritium plasmas to power the fusion reaction. But the process is inherently inefficient — only a small fraction of the fuel actually fuses in the reaction, while the rest gets expelled, even though it still contains valuable, unburned tritium that can be captured and reused.
Today, neither tritium nor the lithium-6 needed to make more of it are produced at anything close to the scale even a single commercial fusion reactor would require to get up and running. And existing isotope separation technologies — largely designed for small-volume defense programs and experimental reactors — aren’t sufficient to bridge the gap.
“When you have a single fusion power plant, that’s going to need about 1,000 times more lithium than anyone is producing today in any country,” Schiller told me, referring to lithium-6. “It would be totally prohibitive to build a fusion power plant at those economics.”
And while it’s at least possible to produce enough of this isotope to supply a future fusion industry by enriching lithium mined from rock, tritium presents a more fundamental problem. Because it’s radioactive and decays relatively quickly, it doesn’t occur naturally in meaningful quantities. Today it’s produced commercially as a byproduct of some fission reactors, but that supply amounts to just a few kilograms per year. A single 1-gigawatt commercial fusion reactor, by contrast, would need an estimated 56 kilograms annually. Meeting that demand will require fusion companies to breed their own tritium inside the reactor, a process that involves fusion-generated neutrons hitting lithium-6 nuclei, splitting them into tritium and helium.
It will also necessitate recycling the substantial amount of tritium that passes through the reactor without burning up. That’s where Marathon’s plasma centrifuge comes in. Centrifuges themselves are nothing new — engineers have used them for decades to separate uranium isotopes for nuclear fuel, spinning the gas at such high speeds that isotopes with different masses separate. Plasma centrifuges work on the same principle and have been studied since the Manhattan Project, but no one has yet successfully commercialized the approach for lithium and hydrogen.
Part of the reason is that, until recently, there simply wasn’t much demand for these isotopes. But the raw materials also present a physics challenge: Lithium and hydrogen isotopes have very similar masses. Separating them thus requires spinning the plasma so rapidly that, historically, the resulting heat has undermined the separation process itself. To address this, Marathon’s proprietary centrifuge tech uses a “partially ionized” plasma, in which some atoms have been stripped of their electrons while others remain neutral. The company says this configuration allows the centrifuge to operate at lower temperatures.
The materials testing lab Covalent has certified Marathon’s lithium-6 enrichment. The company hasn’t had its hydrogen separation results independently verified, though an MIT nuclear engineering professor has reviewed the device’s design. As a participant in ARPA-E’s Vision OPEN program, which solicits and supports ambitious energy projects, Marathon has also presented its hydrogen separation methodology and results at the ARPA-E fusion programs meeting in June.
Now, Schiller told me, the challenge is scaling up the technology’s core systems. “We need bigger magnets, better cooling, bigger power systems, and so that’s a buildout that’s going to take time and more capital,” he said. “But as far as the science is concerned, we feel like it’s at the point where we’re ready to make those kinds of commitments.”
Marathon is now looking to raise capital to build its first commercial pilot facility, with the goal of reaching full-scale production by 2029. Schiller told me the company expects its first full-scale facility to produce tens of tons of lithium-6 per year — enough, he says, to fuel a new gigawatt-scale fusion plant roughly every two years. Marathon also plans to recover and repurpose about 560 kilograms of tritium annually — roughly the amount that cycles through a 1-gigawatt reactor’s fuel system each year, most of which exits in the reactor’s exhaust without ever fusing.
Once fusion reactors are operating at scale, Marathon has a few other tricks up its sleeve. The startup also plans to build an “isotope production” business, using the copious volume of high-energy neutrons generated by fusion to manufacture valuable isotopes. The company made headlines last year with its claim that fusion-generated neutrons could transmute mercury into an unstable isotope that eventually decays into gold — potentially doubling a fusion reactor’s economic output (and proving the old alchemists right). But that work is still theoretical, based on computer simulations rather than peer-reviewed or experimentally validated work.
Marathon certainly has plenty to keep it busy in the near term, though. “There is a really amazing opportunity right now to say, look, the fusion supply chain is ready to go. We can start scaling up,” Schiller told me. “The science will progress in parallel, and we really want to land this together — not wait another 10 years after scientific results come in.”