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The world’s biggest, most functional city might also be the most pedestrian-friendly. That’s not a coincidence.

For cities that want to reduce the number of cars, bike lanes are a good place to start. They are cheap, usually city-level authorities can introduce them, and they do not require you to raise taxes on people who own cars. What if you want to do something more radical though? What would a city that genuinely wanted to get the car out of its citizens’ lives in a much bigger way do? A city that wanted to make it possible for most people to live decent lives and be able to get around without needing a car, even without needing to get on a bicycle?
There is only one city on Earth I have ever visited that has truly managed this. But it happens to be the biggest city on the planet: Tokyo, the capital of Japan.
In popular imagination, at least in the West, Tokyo is both incredibly futuristic, and also rather foreign and confusing. Before I first visited, in 2017, I imagined it to be an incredibly hectic place, a noisy, bustling megacity. I was on holiday and trying to escape Nairobi, the rather sprawling, low-height, and green city I was living in at the time, and I picked Tokyo largely because I wanted to get as far away from Africa as I could. I needed a break from the traffic jams, the power cuts, the constant negotiation to achieve anything, and the heat. I was looking for an escape somewhere as different as I could think of, and I wanted to ride trains around and look at high-tech skyscrapers and not worry about getting splattered by mud walking in the street. I was expecting to feel bowled over by the height of the buildings, the sheer crush of people, and the noise.
Yet when I emerged from the train station in Shibuya, blinking jetlagged in the morning light after a night flight from Amsterdam, what actually caught me off guard was not the bustle but rather how quiet the city is. When you see cliched images of Tokyo, what invariably is shown are the enormous crowds of pedestrians crossing the roads, or Mount Fuji in the background of the futuristic skyline. I expected something like Los Angeles in Blade Runner, I suppose — futuristic and overwhelming. From photos, Tokyo can look almost unplanned, with neon signs everywhere and a huge variety of forms of architecture. You expect it to feel messy. What I experienced, however, was a city that felt almost like being in a futuristic village. It is utterly calm, in a way that is actually rather strange.
And it took me a little while to realize why. There is simply no traffic noise. No hooting, no engine noise, not even much of the noise of cars accelerating on tarmac. Because there are so few of them. Most of the time you can walk in the middle of the street, so rare is the traffic. There are not even cars parked at the side of the road. That is not true of all of Tokyo, of course. The expressways are often packed. Occasionally, I was told, particularly when it snows, or during holidays when large numbers of people try to drive out to the countryside, jams form that can trap drivers for whole days. But on most residential streets, traffic is almost nonexistent. Even the relatively few cars that you do see are invariably tiny, quiet vehicles.
Among rich cities, Tokyo has the lowest car use in the world. According to Deloitte, a management consultancy, just 12 percent of journeys are completed by private car. It might surprise you to hear that cycling is actually more popular than driving in Tokyo — it accounts for 17 percent of journeys, though the Japanese do not make as much of a big deal out of it as the Dutch do. But walking and public transport dwarf both sorts of vehicles. Tokyo has the most-used public transport system in the world, with 30 million people commuting by train each day. This may sound rather unpleasant. You have probably seen footage of the most crowded routes at rush hour, when staff literally push people onto the carriages to make space, or read about young women being groped in the crush. It happens, but it is not typical. Most of the trains I rode were busy but comfortable, and I was able to get a seat.
And what makes Tokyo remarkable is that the city was almost entirely built after the original city was mostly flattened by American bombers in the Second World War. Elsewhere in the world, cities built after the war are almost invariably car-dependent. Think of Houston, Texas, which has grown from 300,000 people in the 1950s to 10 times that now. Or England’s tiny version, Milton Keynes, which is the fastest-growing city in the country. Or almost any developing world city. Since the advent of the automobile, architects and urban planners worldwide have found it almost impossible to resist building cities around roads and an assumption that most people will drive. Tokyo somehow managed not to. It rebuilt in a much more human-centric way.
It may come as a surprise that Japan is home to the world’s biggest relatively car-free city. After all, Japan is the country that gave the world Mitsubishi, Toyota, and Nissan, and exports vehicles all over the world. And in fairness, a lot of Japanese people do own cars. Overall car ownership in Japan is about 590 vehicles per 1,000 people, which is less than America’s rate of about 800 per 1,000, but comparable to a lot of European countries. On average, there are 1.06 cars per household. But Tokyo is a big exception. In Tokyo, there are only 0.32 cars per household. Most Japanese car owners live in smaller towns and cities than the capital. The highest rate of car ownership, for example, is in Fukui Prefecture, on the western coast of Honshu, one of Japan’s least densely populated areas.
And car ownership in Japan is falling, unlike almost everywhere else on Earth. Part of the reason is just that the country is getting older and the population is falling. But it is also that more and more people live in Tokyo. Annually, Japan is losing about 0.3 percent of its population, or about half a million people a year. Greater Tokyo, however, with its population of 37 million, is shrinking by less than that, or about 0.1 percent a year. And the prefecture of Tokyo proper, with a population of 14 million, is still growing. The reason is that Tokyo generates the best jobs in Japan, and it is also an increasingly pleasant place to live. You may think of Tokyoites as being crammed into tiny apartments, but in fact, the average home in Tokyo has 65.9 square meters of livable floor space (709 square feet). That is still very small—indeed, it is less than the size of the average home in London, where the figure is 80 square meters. But the typical household in London has 2.7 people living in it. In Tokyo, it is 1.95. So per capita, people in Tokyo actually have more space than Londoners.
Overall in fact, people in Tokyo have one of the highest qualities of life in the world. A 2015 survey by Monocle magazine came to the conclusion that Tokyo is the best city on Earth in which to live, “due to its defining paradox of heart-stopping size and concurrent feeling of peace and quiet.” In 2021 The Economist ranked it fourth, after Wellington and Auckland in New Zealand, and another Japanese city, Osaka. Life expectancy overall is 84 years old, one of the highest levels of any city on the planet. A good part of this has to do with the lack of cars. Air pollution is considerably lower than in any other city of equivalent size anywhere in the world. Typical commutes are, admittedly, often fairly long, at 40 minutes each way. But they are not in awful smoggy car traffic.

So how has Tokyo managed it? Andre Sorensen, a professor of urban planning at the University of Toronto, who published a history of urban planning in Japan, told me that Japan’s history has a lot to do with it. Japan’s urbanization happened a little more like some poorer countries — quickly. At the start of the 20th century, just 15 percent of Japanese people lived in cities. Now 91 percent do, one of the highest rates of urbanization in the entire world. That rapid growth meant that Tokyo’s postwar growth was relatively chaotic. Buildings sprawled out into rice paddies, with sewage connections and power often only coming later. Electricity is still often delivered by overhead wires, not underground cables. And yet somehow this haphazard system manages to produce a relatively coherent city, and one that is much easier to get around on foot or by public transport than by car.
Part of the reason, Sorensen explained to me, is just historical chance. Japanese street layouts traditionally were narrow, much like medieval alleys in Europe. Land ownership was often very fragmented, meaning that house builders had to learn to use small plots in a way that almost never happened in Europe or America. And unlike the governments there, the government in postwar Japan was much more concerned with boosting economic growth by creating power plants and industrial yards than it was with creating huge new boulevards through neighborhoods. So the layouts never changed. According to Sorensen’s research, 35 percent of Japanese streets are not actually wide enough for a car to travel down them. More remarkably still, 86 percent are not wide enough for a car to be able to stop without blocking the traffic behind it.
Yet the much bigger reason for Tokyo’s high quality of life is that Japan does not subsidize car ownership in the way other countries do. In fact, owning a car in Tokyo is rather difficult. For one thing, cars are far more enthusiastically inspected than in America or most of Europe. Cars must be checked by officials every two years to ensure that they are still compliant, and have not been modified. That is true in Britain too, but the cost is higher than what a Ministry of Transport test costs. Even a well-maintained car can cost 100,000 yen to inspect (or around $850). On cars that are older than 10 years, the fees escalate dramatically, which helps to explain why so many Japanese sell their cars relatively quickly, and so many of them end up in East Africa or Southeast Asia. On top of that there is an annual automobile tax of up to 50,000 yen, as well as a 5 percent tax on the purchase. And then gasoline is taxed too, meaning it costs around 160 yen per liter, or about $6 a gallon, less than in much of Europe, but more than Americans accept.
And even if you are willing to pay all of the taxes, you cannot simply go and buy a car in the way that you might in most countries. To be allowed to purchase a car, you have to be able to prove that you have somewhere to park it. This approval is issued by the local police, and is known as a shako shomeisho, or “garage certificate.” Without one, you cannot buy a car. This helps to explain why the Japanese buy so many tiny cars, like the so-called Kei cars. It means they can have smaller garages. Even if the law didn’t exist though, owning a car in Japan without having a dedicated parking space for it would be a nightmare. Under a nationwide law passed in 1957, overnight street parking of any sort is completely illegal. So if you were to somehow buy a car with no place to store it, you could not simply park it on the street, because it would get towed the next morning, and you would get fined 200,000 yen (around $1,700). In fact, most street parking of any sort is illegal. There are a few exceptions, but more than 95 percent of Japanese streets have no street parking at all, even during the day.
This, rather than any beautiful architecture, explains why Tokyo’s streets feel so pleasant to walk down, or indeed to look at. There are no cars filling them up. It also means that land is actually valued properly. If you want to own a car, it means that you also have to own (or at least rent) the requisite land to keep it. In rural areas or smaller towns, this is not a huge deal, because land is relatively cheap, and so a permit might only cost 8,000 to 9,000 yen, or about $75 a month. But in Tokyo, the cost will be at least four times that. Garages in American cities can cost that much too, but in Japan there is no cheap street parking option, as in much of New York or Chicago. Most apartment buildings are constructed without any parking at all, because the developers can use the space more efficiently for housing. Only around 42 percent of condominium buildings have parking spaces for residents. Similarly, even if you own a parking space, it is almost never free to park anywhere you might take your car. Parking in Tokyo typically costs 1,000 yen an hour, or around $8.50.
This is a big disincentive to driving. Sorensen told me that when he lived in Tokyo, some wealthy friends of his owned a top-end BMW, which they replaced every few years, because they were car nuts. But because they did not have anywhere to park it near their home, if they wanted to use it, they had to take public transport (or a taxi) to get to it at its garage. As a result, they simply did not use their car very much. In their day-to- day life, they used the trains, the same as everybody else, or took taxis, because that was cheaper than picking up the car. This sort of thing probably helps to explain why the Japanese, despite relatively high levels of car ownership, do not actually drive very far. Car owners in Japan typically drive around 6,000 kilometers per year. That is about half what the average British car owner drives, and less than a third of what the average American does.
Parking rules are not, however, the limit of what keeps cars out of Tokyo. Arguably, an even bigger reason is how infrastructure has been funded in Japan. That is, by the market, rather than directly by taxes. In the 1950s and ’60s, much like Europe and the United States, Japan began building expressways. But unlike in Europe and America, it was starting from a considerably more difficult place. In 1957, Ralph J. Watkins, an American economist who had been invited to advise the Japanese government, reported that “the roads of Japan are incredibly bad. No other industrial nation has so completely neglected its highway system.” Just 23 percent of roads were paved, including just two-thirds of the only highway linking Osaka, Japan’s historical economic hub, to Tokyo.
But unlike America, the idea of making them free never seemed to cross politicians’ minds, probably because Japan in the postwar era was not the world’s richest country. Capital was not freely available. To build the roads, the national government formed corporations such as the Shuto Kōsoku-dōro Kabushiki-gaisha, or Metropolitan Expressway Company, which was formed in greater Tokyo in 1959. These corporations took out vast amounts of debt, which they had to repay, so that the Japanese taxpayer would not be burdened. That meant that tolls were imposed from the very beginning. The tolls had to cover not just the construction cost, but also maintenance and interest on the loans. Today, to drive on the Shuto Expressway costs from 300 to 1,320 yen, or $2.50 to $11 for a “standard-size” automobile. Overall, tolls in Japan are the most expensive in the world — around three times higher than the level charged on the private autoroutes in France, or on average, about 3,000 yen per 100 kilometers ($22 to drive 62 miles).
What that meant was that, from the beginning, roads did not have an unfair advantage in their competition with other forms of transport. And so in Japan, unlike in almost the entire rest of the rich world, the postwar era saw the construction of enormous amounts of rail infrastructure. Indeed, at a time when America and Britain were nationalizing and cutting their railways to cope with falling demand for train travel, in Japan, the national railway company was pouring investment into the system. The world’s first high-speed railway, the Tokaido Shinkansen, was opened in 1964 to coincide with the Tokyo Olympics, with a top speed of 210 kilometers per hour. That was almost double what trains elsewhere mostly managed. From 1964 to 1999, the number of passengers using the Shinkansen grew from 11 million annually to more than 300 million.
Sorensen told me about how in the 1950s and ’60s, the trains were a huge point of national pride for the Japanese government, a bit like car industries were elsewhere. “And justifiably! It was a fantastic invention. To say we can make electric rail go twice as fast. What an achievement.” Thanks to that, the railways ministry became a huge power center in government, rather than a neglected backwater as it often had become elsewhere. In rail, the Japanese “built up expertise in engineering, in bureaucratic resources and capacities, and political clout that just lasted,” he told me. “Whereas the road-building sector was weak.” Elsewhere, building roads became a self-reinforcing process, because as more was poured into constructing them, more people bought cars and demanded more roads. That did not happen in Japan. Instead, the growth in railway infrastructure led to growth in, well, more railway infrastructure.
If you visit Tokyo now, what you will find is that the most hectic, crowded places in the city are all around the train and subway stations. The reason is that Japan’s railway companies (the national firm was privatized in the 1980s) do not only provide railways. They are also big real estate investors. A bit like the firm that built the Metropolitan Railway in the 1930s in Britain, when Japan’s railway firms expanded service, they paid for it by building on the land around the stations. In practice, what that means is that they built lots of apartments, department stores, and supermarkets near (and directly above) railway stations, so that people can get straight off the train and get home quickly. That makes the trains more efficient, because people can get where they need to go without having to walk or travel to and from stations especially far. But it also means that the railways are incredibly profitable, because unlike in the West, they are able to profit from the improvement in land value that they create.
What this adds up to is that Tokyo is one of very few cities on Earth where travel by car is not actively subsidized, and funnily neither is public transport, and yet both work well, when appropriate. However, Tokyo is not completely alone. Several big cities across Asia have managed to avoid the catastrophe (cartastrophe?) that befell much of the western world. Hong Kong manages it nearly as well as Tokyo; there are just 76 cars per 1,000 people in the city state. So too does Singapore, with around 120 per 1,000 people. What those cities have in common, which makes them rather different from Japan, is a shortage of land and a relentless, centralized leadership that recognized early on that cars were a waste of space.
Unfortunately, replicating the Asian model in countries in Europe, America, or Australia from scratch will not be easy. We are starting with so many cars on our roads to begin with, that imposing the sorts of curbs on car ownership that I listed above is almost certainly a political nonstarter. Just look at what happens when politicians in America or Britain try to take away even a modest amount of street parking, or increase the tax on gasoline. People are already invested in cars, sadly. And thanks to that, there is also a chicken-and-egg problem. Because people are invested in cars, they live in places where the sort of public transport that makes life possible for the majority of people in Tokyo is simply not realistic. As it is, constructing rail infrastructure like Japan’s is an extraordinarily difficult task. Look at the difficulties encountered in things like building Britain’s new high-speed train link, or California’s, for example.
And yet it is worth paying attention to Tokyo precisely because it shows that vast numbers of cars are not necessary to daily life. What Tokyo shows is that it is possible for enormous cities to work rather well without being overloaded by traffic congestion. Actually, Tokyo works better than big cities anywhere else. That is why it has managed to grow so large. The trend all over the world for decades now has been toward greater wealth concentrating in the biggest metropolises. The cost of living in somewhere like New York, London, or Paris used to be marginally higher than living in a more modest city. That is no longer the case. And it reflects the fact that the benefits of living in big cities are enormous. The jobs are better, but so too are the restaurants, the cultural activities, the dating opportunities, and almost anything else you can think of. People are willing to pay for it. The high cost of living is a price signal — that is, the fact that people are willing to pay it is an indicator of the value they put on it.
Especially in this post-pandemic era where many jobs can be done from anywhere, lots of New Yorkers could easily decamp to, say, a pretty village upstate, and save a fortune in rent, or cash in on their property values. Actually, hundreds of thousands do every year (well, not only to upstate). But they are replaced by newcomers for the simple reason that New York City is, if you set aside the cost, a pretty great place to live. And yet, if everyone who would like to live in a big city is to be able to, those cities need to be able to grow more. But if they continue to grow with the assumption that the car will be the default way of getting around for a significant proportion of residents, then they will be strangled by congestion long before they ever reach anything like Tokyo’s success. People often say that London or New York are too crowded, but they are wrong. They are only too crowded if you think that it is normal for people to need space not just for them but also for the two tons of metal that they use to get around.
The sheer anger of motorists might mean that banning overnight parking on residential streets proves difficult. But if we want to be bold, some of Tokyo’s other measures are more realistic. We could, for example, do a lot more to build more housing around public transport, and use the money generated to help contribute to the network. According to the Centre for Cities, a British think tank, there are 47,000 hectares of undeveloped land (mostly farmland) within a 10-minute walk of a railway station close to London or another big city. That is enough space to build two million homes, more than half of which would be within a 45-minute commute to or from London. The reason we do not develop the land at the moment is because it is mostly Metropolitan Green Belt, a zoning restriction created in the late 1940s by the Town and Country Planning Act intended to contain cities and stop them sprawling outward. But the problem with it as it works in Britain at the moment is that it does not stop sprawl — it just pushes it further away from cities, into places where there really is no hope of not using a car.
Developing the green belt too would not be popular. People have an affection for fields near their homes, and they do not necessarily want the trains they use to be even more crowded. But there are projects that show it is possible to overcome NIMBYism. In Los Angeles in 2016, voters approved the Transit Oriented Communities Incentive Program, which creates special zoning laws in areas half a mile from a major transit stop (typically, in L.A., a light rail station). This being Los Angeles, it is fairly modest. One of the rules is that the mandatory parking minimums applied are restricted to a maximum of 0.5 car parking spaces per bedroom, and total parking is not meant to exceed more than one space per apartment, which is still rather a lot of parking. But nonetheless, it does allow developers to increase the density of homes near public transport, and it has encouraged developers to build around 20,000 new homes near public transport that probably would not have been constructed otherwise. These are small but real improvements.
Ultimately, no city will be transformed into Tokyo overnight, nor should any be, at least unless a majority of the population decides that they would like it. I am trying to persuade them; for now, not everyone is as enamored with the Japanese capital as I am. But NIMBYism and other political problems can be gradually overturned, if the arguments are made in the right way, even in the most automotive cities.
This article was excerpted from Daniel Knowles’ book Carmageddon: How Cars Make Life Worse and What to Do About It, published by Abrams Press ©2023.
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Current conditions: A wave of summer heat is headed for the East Coast, with midweek temperatures surpassing 90 degrees Fahrenheit in Washington, D.C. • Guam and the Northern Mariana Islands are bracing for winds of up to 190 miles per hour as Super Typhoon Sinlaku bears down on the U.S. territories • At least 30 people have died in floods in Yemen, which just recorded its highest rainfall in five years.
The Trump administration is holding up some funding for grants at the National Oceanic and Atmospheric Administration, The Hill reported. On April 1, the University of Colorado put out a statement saying that a federal pause on funding had put scientists who collect data about the atmosphere “at risk for elimination” after the White House Office of Management and Budget had “not released these funds.” The university’s Cooperative Institute for Research in Environmental Sciences said that roughly 30 days before running out of funds to pay scientists, “we were informed that NOAA has put a pause on all grant actions.”
As I told you back in December, the Trump administration is also working to dismantle the National Center for Atmospheric Research in Colorado, an institution credited with many of the biggest scientific breakthroughs in our understanding of weather and climate over the past 66 years since its founding. In a post on X at the time, Russell Vought, the director of the White House’s Office of Management and Budget, called the institute “one of the largest sources of climate alarmism in the country,” and said the administration would be “breaking up” its operations.
Secretary of Energy Chris Wright is scheduled to testify Wednesday morning before the House Committee on Appropriations to defend the White House’s latest budget request for his agency. He’s not the only chieftain of a federal agency with relevance to Heatmap readers who’s coming before Congress this week.
U.S. Customs and Border Protection plans to launch the first phase of what’s called the Consolidated Administration and Processing of Entries tool in the agency’s automated commercial secure data portal to allow companies to request refunds of Trump administration tariffs the U.S. Supreme Court ruled unlawful earlier this year. Solar companies are among the thousands of American businesses that filed complaints with the U.S. Court of International Trade for refunds prior to the Supreme Court’s ruling. Those, according to Solar Power World, include American Wire Group, Canadian Solar, GameChange Solar, Fluke, Hellerman Tyton, Kinematics, JA Solar, Jinko Solar, Longi, Merlin Solar, Qcells, and Trina Solar.
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Established in early 2021, California Community Power is a quasi-governmental organization formed out of nine power providers across the Golden State. On Monday, the agency inked a series of deals with geothermal power developers to expand what’s widely considered one of the most promising clean-energy sources for California, which has some of the continent’s best hot-rock resources. XGS Energy, the Houston-based startup promising to build next-generation closed-loop geothermal systems, announced a deal to build 115 megawatts of power in the state. Zanskar, the geothermal company using AI to locate untapped conventional geothermal resources, also signed an agreement with the agency.
Zanskar in particular ranked among the most promising climate-tech startups on the U.S. market in Heatmap’s poll of experts earlier this year. The company last year announced its biggest find yet, Heatmap’s Katie Brigham reported last year. XGS, meanwhile, is drawing support from the nuclear industry, as I previously reported for Heatmap.
The developer behind a major Massachusetts offshore wind farm is suing its turbine manufacturer in a bid to keep the company from backing out of the project. By February, the Vineyard Wind project off Cape Cod had installed 60 of the project’s 62 turbines, as I reported at the time. Yet the parent company behind GE Renewables, the maker of the project’s turbines, said “it would be terminating its contracts for turbine services and maintenance at the end of April,” the Associated Press reported. GE Vernova, the parent company, says Vineyard Wind owes it $300 million already.
The war in Iran is taking a toll on Central African minerals. Miners in the Democratic Republic of the Congo are curbing output of copper and cobalt as the war cuts supplies of sulfuric acid needed for leaching minerals out of rock, Reuters reported. Mine managers are reducing cobalt production to conserve chemicals.
The deal represents one of the largest public-private partnerships in the history of the national labs.
I’ll admit, I thought I might be done covering fresh fusion startups for a while. In the U.S., at least, the number of new industry entrants has slowed, and most venture capital now flows towards more established players such as Commonwealth Fusion Systems and Helion. But in February, a startup called Inertia Enterprises made headlines with its $450 million Series A raise. It’s aiming to commercialize fusion using the physics pioneered at Lawrence Livermore National Laboratory, the only place yet to achieve scientific breakeven — the point at which a fusion reaction produces more energy than it took to initiate it.
That achievement first came in 2022 at the lab’s National Ignition Facility in Berkeley, California. On Tuesday, Inertia announced that it’s deepening its partnership with Lawrence Livermore, creating one of the largest private sector-led partnerships in the history of the national lab system. This collaboration involves three separate agreements that allow Inertia to work directly with the lab’s employees on research and development, while also giving the startup access to nearly 200 Lawrence Livermore patents covering fusion technology.
The startup’s team isn’t merely a group of enthusiasts galvanized by the national lab’s fusion milestone. Alongside Twilio’s former CEO Jeff Lawson and fusion power plant designer Mike Dunne, Inertia’s other co-founders is Annie Kritcher, a senior employee at Lawrence Livermore who has led the physics design for NIF’s fusion energy experiments since 2019.
“We’re not starting from zero,” Kritcher told me, putting it mildly. “And that was really, really important to me when I decided to co-found this company.” Or as Lawson told me after the company’s fundraise in February, “the government put 60 years and $30 billion into NIF trying to get that thing to work.”
The technical approach pursued by Lawrence Livermore — and now by Inertia — is called inertial confinement fusion. In this system, high-powered lasers are directed at a millimeter-scale pellet of fusion fuel, typically a mixture of the hydrogen isotopes deuterium and tritium. The laser energy rapidly compresses and heats the pellet to extreme temperatures and pressures, driving the nuclei to fuse and releasing enormous amounts of energy. But NIF didn’t build its system for commercial purposes. Rather, its primary mission is to support the domestic nuclear weapons stockpile by recreating the extreme conditions inside a nuclear detonation, allowing scientists to study how U.S. weapons perform without conducting explosive tests.
To translate the lab’s research into a commercially viable device, Kritcher explained, Inertia must significantly increase the lasers’ efficiency and power output, targeting a system roughly 50 times more powerful than existing lasers of its class. The startup is also working to scale production of its fusion targets to drive down costs and enable mass manufacturing.
Inertia is not the only company attempting to commercialize this general approach, however. Back in 2021, as Lawrence Livermore moved closer to its breakeven moment, the future founders of the startup Xcimer Energy were taking note. Convinced that the fundamental physics of inertial confinement had been proven, they thought, “if we’re going to do this, we have to do it now,” Xcimer's CTO, Alexander Valys, told me a few years ago. He and his co-founder quit their day jobs, and Xcimer went on to raise a $100 million Series A round in 2024. Others joined in on the hype, too — the Fusion Industry Association reports 13 fusion companies that were founded or emerged from stealth between summer 2022 and summer 2023, a record for the sector.
Kritcher told me that none are adhering as closely to NIF’s successful design as Inertia. “There are fundamental technical differences between us and the other laser approaches,” she told me, explaining that while Xcimer and others are using broadly similar methodologies to produce a hot, dense plasma, the underlying physics behind their plan diverges significantly. Xcimer, for instance, is developing a novel laser architecture that hasn’t yet been demonstrated at scale, along with a different fuel capsule design than the one validated by NIF.
Kritcher will be allowed to continue her work at the lab thanks to what the company describes as a “first-of-its-kind agreement” enabled by the 2022 CHIPS and Science Act, which allows scientists at the national labs to participate in commercialization efforts with the goal of accelerating the transfer of knowledge to the private sector.
For the fusion engineer, it’s the ultimate dream come true. She first arrived at Lawrence Livermore as a summer intern in 2004, just before her senior year at the University of Michigan, and “fell in love with the lab and the NIF project,” which was still under construction at the time. She opted to attend the University of California, Berkeley for her masters and PhD in nuclear engineering so that she could continue her work there.
“I was starstruck by the possibility of fusion energy and [it having] such a big impact on humanity, and that really kept me going for a long time,” she told me. But after the NIF facility was finally completed in 2009, it failed to achieve ignition by its initial 2012 target.
By then, Kritcher was a postdoctoral fellow, and attention at NIF began to shift toward supporting the nation’s nuclear stockpile. Fusion energy was “always in the back of my mind, driving me day to day,” she said, “but you sort of forget about it, and you lose a little bit of that excitement and spark.” Under her guidance, NIF ultimately reached that watershed moment, which has since been replicated numerous times. And when it did, "it just reopened all those old inspirational feelings and motivations and excitement and it was like a 180 turning point where we all just go, oh, fusion energy is possible again with this approach.”
Many of the lab’s employees feel similarly, she said, and this close collaboration will allow some of the nation’s foremost experts in inertial confinement to work with the startup across a range of technical capabilities, including “the laser side, the target fabrication side, the simulations team side, the code development side, our physics design side,” Kritcher enumerated.
Inertia is looking to bring its first pilot plant online in the “2030s to 2040s,” she told me. By contrast, Commonwealth Fusion Systems — the most well-capitalized company in the sector — plans to connect its first plant to the grid early next decade, while Xcimer is targeting 2035. Kritcher is unfazed, though. While she acknowledges that other companies might complete their facilities sooner, she argues that Inertia still has an upper hand given that NIF effectively serves as the startup’s demonstration plant, something no other company has built.
Not to mention that all of the sector’s projected timelines remain highly speculative. There are serious technical and economic challenges that would-be fusion energy companies will have to overcome — Inertia not excepted — and the industry’s status 10 years down the line remains anyone’s guess. What’s crystal clear, however, is that a serious new contender has entered the race.
Big questions about naval strategy and the oil economy with Cornell University’s Nicolas Mulder.
After negotiations between the United States and Iran broke down Sunday without a deal, the United States Central Command said it would “begin implementing a blockade of all maritime traffic entering and exiting Iranian ports” Monday morning.
It’s hardly like traffic through the Strait of Hormuz had been unencumbered before that. The strait has been largely closed to through traffic since the beginning of March thanks to the threat of Iranian strikes on ships going in and out of the Persian Gulf. That has remained the case even after the ceasefire deal was supposed to have opened up the waterway last week. Only a few countries have been able to get their tankers out, mostly those with close trade relationships with Iran, including China.
President Trump has been seeking to reverse that state of play and open the strait to non-Iranian traffic (e.g. oil, liquified natural gas, and fertilizer coming in and out of the Gulf states), whether by badgering European allies to help clear the strait and by having U.S. Navy ships traverse the channel to clear mines and demonstrate it’s safe to navigate. He appears to have ultimately settled on blockading the blockaders.
The president said Monday on Truth Social that 34 ships had sailed through the strait on Sunday, a number that has not been confirmed by third party sources. In the run-up to the U.S. blockade, about 10 to 12 ships were sailing through the strait per day, according to marine data service Kpler and The New York Times.
So, is the blockade an escalation of U.S. pressure on Iran? A violation of the ceasefire? A “pacific blockade” designed to pressure Iran without resorting to direct strikes? And how would it work, anyway?
I spoke with Nicolas Mulder, an assistant professor of history at Cornell University and the author of The Economic Weapon: The Rise of Sanctions as a Tool of Modern War, to try and get some of my questions answered. This interview has been condensed and edited for clarity.
Let’s start from the beginning. What is a naval blockade? And how does it different from typical naval warfare?
A naval blockade is actually interesting because it is a form of warfare that has been quite regulated for quite a long time already under international law. A lot of our modern understanding of the laws of belligerence and neutrality actually comes from blockades because they impose an important stricture on international maritime traffic. As a result, they raise all sorts of questions about who wars are fought between, and what wars mean for the civilian economies of the countries involved, and what they mean for the relationship of the belligerent states and third countries.
For most of U.S. history, the U.S. was not the blockader, but the neutral wanting to bypass blockades. The reason that the United States concretely intervened in the First World War and began to really involve itself with the power politics of Eurasia in 1917 is because it insisted on its neutral rights to trade with Britain when Germany had declared an unrestricted submarine warfare campaign that was effectively a blockade of the British Isles.
Even before that, the Union used it against the Confederacy.
In the 18th century, all the big great power wars — the Seven Years War, the various succession wars, the Napoleonic Wars — all of those involved blockades.
What I find interesting is that we have this ceasefire. We have these negotiations, which are apparently still going on. But then we also have the blockade. You seem to be arguing that blockades are a part of warfare. So, is this implying that the U.S. Navy is still potentially going to be shooting at stuff, even if there’s a so-called ceasefire?
That’s the big uncertain aspect of the current situation. We are not back into the same war that we were in last week before the ceasefire took effect. The way I would interpret this is that it’s a kind of fudge. From the perception of the Trump administration, it needs to do something to not look weak, but at the same time wants to avoid the risks of a full resumption of kinetic warfare and a massive air campaign, which they had pursued for six weeks to very mixed and disappointing effects.
The one historical parallel that I think can help us make sense of what they may be attempting to do now is the practice in the 19th century of “pacific blockade.” There were several conflicts, beginning in the 1820s with the Greek War of Independence and then through a whole bunch of Latin American wars and Asian conflicts, where European great powers would blockade small countries — not to declare war on them, but to prevent any of their ships from entering or leaving to put serious pressure on them.
What they were doing in that situation was to use wartime levels of pressure without initiating the full war because they knew that the target states were basically too weak to retaliate and did not have the naval power to contest that blockade.
How can we see this operation in Iran as part of a continuum of using these strangulation-type strategies against much weaker opponents?
One way to interpret what they’re trying to do now is to apply that Venezuela-Cuba template to Iran, and to wager that if they play this carefully, they might be able to bring real economic pressure to bear without provoking Iran into as full-scale a retaliation as it was undertaking before.
But that Venezuela-Cuba template is difficult to implement in the case of Iran for two simple reasons. One is just that Iran has, of course, shown that it has quite a lot of military capacity to retaliate with drones and missiles, and also mines and small ships and submarines. It also has the ability to widen its own maritime disruption in the region, for example by working with the Houthis to really stem the flow of traffic through the Bab-el-Mandeb Strait.
What works in the Western Hemisphere, where the United States has a really unrivaled military dominance, may not be reproducible in this strategic theater.
What does the geography tell you about the ability to impose or contest a blockade like this?
They may be doing it with multiple rings, or multiple screens — a light initial screen, and then bigger barriers of ships a bit further away, so as to not risk most of their force too close to the Iranian coastline. We saw in the early phase of the war that some carrier strike groups began to operate over time further and further away from the Iranian coast, presumably to avoid the risk of being hit with missiles and drones.
In this case, one of the questions is, what kind of resources are needed to keep that going? The U.S. did run a blockade against Iraq for most of the 1990s that was in the Persian Gulf itself, which is very narrow. Iraq’s ports are a tiny sliver of land that ends in the Persian Gulf. So that was a very small stretch of coastline.
Iran should still be manageable, but it will require a wider screen, and potentially one that really crosses the entire Arabian Sea somewhere from the southern coast of Oman, diagonally, northeastwards to Pakistan, or at least the Pakistan-Iranian border, and potentially a bit further out. And if there is also interference in the Red Sea, then the U.S. Navy is going to have to route most of disabled forces all the way around Cape of Good Hope to move that whole force into the Indian Ocean.
I think that the Red Sea contingency is quite important to how this shapes up.
CENTCOM said yesterday that this blockade is on ships going in and out of Iranian ports. I wonder if this is unique historically — both a blockade of Iran and trying to impose freedom of navigation elsewhere?
It’s interesting, right? Because indeed, there is the commitment to freedom of navigation. But then it also has been suggested that the U.S. Navy will stop all ships that have paid any toll or transit fee to the [Islamic Revolutionary Guard Corps], and that paying that toll ipso facto would make their passage illegal. For that I don’t know any good historical precedent.
The other historical precedent is probably actually the Ottoman Empire and Russia and World War I. The Ottoman Empire was bottling up Russia’s Black Sea Fleet in the Black Sea by its control over the Turkish straits, which actually imposed a really serious, long run cost on the Russian economy. It’s one of the things that really fed us in the Russian Revolution. But at the same time, the Ottoman Empire was itself being blockaded by British and French forces in the Mediterranean.
Iran is blockading [Gulf Cooperation Council] states selectively — though of course, it is allowing through some shipments. But those shipments are then going to be intercepted, presumably by the Americans. So the de facto result of it is that no one is really going to be able to leave the Gulf. And that’s kind of where I see this game theoretically ending up.
So it seems like the result of this won’t be hugely different than what things were a few weeks ago, just with fewer Iranian ships getting out.
Also ships of those countries that negotiated transit with Iran.
If you looked at the news coming out of Asia and the diplomatic communiques of a large number of Asian states that brokered bilateral arrangements with Iran — so Pakistan, India; Bangladesh had done so; China, of course — but also countries that have otherwise fairly good links with the United States — the Philippines, Malaysia, Vietnam — all of them had essentially accepted that some payment to the IRGC was now the new cost of doing business. They were so desperately in need of energy supplies for the population that they decided to enter negotiations, even if, in principle, they would prefer freedom of navigation.
The likely diplomatic contestation or diplomatic issues coming out of this blockade are also going to be related to Asia, and that’s where I would focus our attention.