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Stumpy stands alone.
It’s hard to miss, rising scraggily up from the soil on the southeast side of the Tidal Basin in Washington, D.C. It picturesquely frames the Washington Monument with an outstretched limb, which also happens to be its only limb.
Stumpy is a Yoshino Cherry tree, a Prunus x yedoensis, one of the thousands that line the water of the Tidal Basin, and it’s been having a bit of a rough time lately. The nearby seawall, built 80-odd years ago, has slowly been settling into the mud and the muck, dropping about three feet in the time since it was built. High tide is also a foot higher now, and twice a day Stumpy’s roots are inundated with brackish water that’s saltier than the nearby Potomac River — a state of being that is no good for a tree. The trunk looks mostly hollow, like someone took a few large scoops out of it. All but one of the branches have rotted away and been trimmed by its caretakers at the National Park Service, leaving Stumpy with a windblown toupee of sticks, leaves, and buds.
Naturally, people are obsessed.
“This is my ninth cherry blossom season and I would be hard pressed to find another tree that’s gotten either a name or that sort of fame,” said Mike Litterst, Chief of Communications for the National Parks Service and Stumpy’s de facto spokesman. “People are literally lining up to take photos with it this year, and somebody’s even got Stumpy t-shirts now.”
Stumpy’s story began as a Reddit post in 2020, when a user said the tree was “as dead as my love life.” Stumpy is, of course, still kicking, and the Redditor met a girl, but for reasons unknown to everyone including the National Parks Service, the tree has been more popular this year than ever before. Perhaps D.C. was primed for Stumpy’s resurgence; back in December, residents of the Columbia Heights neighborhood became similarly obsessed with a diminutive Christmas tree they’d nicknamed Tiny Timber.
We like to tell stories about trees, and lately I’ve noticed them cropping up more often. Perhaps this is just frequency bias, the detritus of spending the early pandemic in a house with a maple tree in the backyard, where for the first time in my life I found myself paying attention to arboreal rhythms as the seasons changed. But we all, to some extent, became amateur naturalists in lockdown, and the trees (and the birds) are what remain.
Stumpy and Tiny Timber both belong to the Charlie Brown class of trees, the ones that, because of their smallness and sadness and apparent untree-ness, evoke a kind of empathy that allows us to give human emotions to them. Litterst thinks this is why Stumpy is so popular this year — it’s an underdog, and we like underdog stories.
Then there are the stories of magic and majesty, like The Giving Tree and the Kalaloch Tree of Life in Washington State and The Overstory, winner of the 2019 Pulitzer Prize in Fiction. These are the trees that make us feel small; we gape at their stoic enormity, the generosity with which they share their shade. I think these are the same reasons why tree planting is such a popular, if misguided, climate solution: We are so drawn to the idea of trees being older and wiser than us, we take such comfort in their leaves and branches, that we can’t help but hope they will fix our mistakes for us.
They won’t, of course, and perhaps we ought to reexamine our expectations of trees. Their effects on our planet are matters of circumstance rather than agency; trees, after all, may have accidentally killed off half the planet when they evolved roots a few hundred million years ago. They didn’t know what they were doing then, and they don’t now — an idea I find somewhat freeing, for it lets a tree simply be a tree.
Take Stumpy. Peak bloom was over by the time I made the pilgrimage to see Stumpy for myself: Its flowers and the crowds were both gone, although one couple briefly stopped on their walk to quickly chuckle at Stumpy before continuing.
There’s a sort of solemn quietude to Stumpy without the crowds. There were other, more conventionally beautiful cherry trees nearby, a few of them still hanging onto their pink and white flowers. But Stumpy, standing by the water on its own, with its one lone branch pointing towards the Washington Monument, bucked the trend, as if someone had dropped in a bonsai among the rest.
It reminded me a bit of another out-of-place plant I’d seen, back in 2019, when a tomato sprouted in a wooden piling in the East River, just off Brooklyn Bridge Park. That, too, was the kind of thing that made people stop and point and laugh, but with the kind of laugh one emits when they crawl to the edge of a cliff and look out at the sea yawning below. An errant seed or a stubborn tree: These are conduits for wonder, whispers of the ecosystems we inhabit.
They’re also reminders of our roles as stewards. Despite how it looks, the fact that Stumpy flowered means it’s in pretty good shape overall, Litterst told me, and the parts of the trunk that deliver nutrients to and from the remaining branch are still working as they should. Plans for a new, improved seawall — one that’s embedded in the bedrock unlike its predecessor, so it doesn’t sink — are in the works, with construction planned to begin next year. The National Parks Service doesn’t know how long Stumpy has left, but if it manages to hold out until the seawall is finished it’ll eventually be spared the rising tides and could live to see some of its brethren take their places alongside it.
I’m sure they’ll be pretty, in the way cherry blossoms always are. But I’ll still be going back for Stumpy.
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The spinoff of Lawrence Livermore National Lab has a new 10-point plan to get onto the grid by the 2030s.
One of fusion energy’s newest startups, Inertia Enterprises, is betting that the fastest route to commercial fusion runs through one of the field’s oldest ideas. The company, which raised a $450 million Series A earlier this year, plans to build a power plant based on the laser-driven fusion system pioneered at Lawrence Livermore National Laboratory’s — the only tech yet to have produced more energy from a fusion reaction than it took to initiate it. Now, Inertia has shared its commercialization roadmap exclusively with Heatmap, detailing the 10 near-term capabilities it must demonstrate before this landmark experiment can become a grid-scale power plant by the mid-2030s.
The roadmap offers a route from the national lab’s impressive but commercially impractical fusion demonstrations to an economical power plant capable of producing electricity for the grid. At its core are a set of milestones — mostly aimed at developing cheap, mass-manufacturable components — that Inertia says it must clear before those individual systems can be integrated into a working plant. This road is not necessarily linear, however, as various teams will likely be working on many of these goals simultaneously.
At least the physics of Inertia’s approach are already proven, the startup’s CEO Jeff Lawson told me, pointing to the fusion experiments at Lawrence Livermore’s National Ignition Facility as a proof-of-concept. The lab’s demonstration of net energy gain caps more than six decades and $30 billion (in 2026 dollars) of U.S. fusion research. The remaining challenges, he argued, are all engineering-related, requiring “elbow grease, hard work, and smart people” rather than breakthroughs in fusion science.
"It seems to us like a startup or a commercial company of any variety should be focused on commercializing a proven scientific result, as opposed to actually trying to demonstrate the basic science to begin with," Lawson told me. Basic science, he argues, is better left to national labs and universities, where researchers can pursue "unbounded problems" that don’t align with the expectations and timelines of venture-backed startups.
Indeed, no fusion startup has yet achieved scientific breakeven, the milestone Lawrence Livermore first hit in 2022, and has since repeated numerous times. But leading players such as Commonwealth Fusion Systems and Helion Energy maintain that it’s only a matter of time before they validate the physics behind their own reactor designs, which they claim will be highly cost-competitive.
Lawson, on the other hand, readily acknowledged that Lawrence Livermore’s tech is uneconomical in its current form. His bet is simply that the more predictable path to a commercial reactor is to drive down the cost of the lab’s validated fusion approach, known as inertial confinement. This system relies on high-powered lasers firing at a millimeter-scale pellet of fusion fuel, compressing it to extreme temperatures and pressures until the atoms fuse. Today, the National Ignition Facility makes each individual fusion target by hand, a workable solution given that it only uses about a dozen per year.
That production model, however, isn’t remotely plausible for a grid-scale power plant. Because each fusion reaction lasts just a fraction of a billionth of a second, a commercial facility must fire its lasers at a fresh target about 10 times per second to generate continuous electricity — requiring the production of hundreds of millions of targets each year.
Scaling production to roughly a million pellets per day and making them inexpensive enough for commercial operation without compromising the strength or precision required for fusion ignition is central to Inertia’s roadmap. That includes goals five, seven, eight and nine — industrializing the manufacturing of the carbon shells that hold the fusion fuel, making the thin films that hold those carbon shells both durable and cheap, scaling up and automating fusion target assembly, and speeding up how fast targets are filled with the requisite deuterium-tritium fuel.
The other central focus of the roadmap is the laser system, which will ultimately consist of 1,000 individual units operating in concert to compress and heat the fusion fuel. Key priorities include reducing the system’s cost (goal two), dramatically increasing its firing cadence (goal three), and bolstering its durability to withstand high-intensity operations (goal four). Goal six also complements these efforts, calling for the development of a control system capable of tracking moving fusion targets to precisely align each laser shot.
Goals one and 10 bookend the journey with some broader milestones. The first focuses on increasing the fusion target’s energy gain — the ratio of fusion energy produced to laser energy delivered — to more than 25 times ignition. Today, the National Ignition Facility’s best-performing laser shot has yielded a gain of just over four times what it took to start the reaction. Goal 10 then zooms out to the ultimate objective: integrating all these technologies into a commercially viable power plant that can deliver either electricity or industrial heat to end customers.
To reach that point, Inertia has embarked on an industrial engineering hiring spree, recruiting folks with experience taking complex hardware systems from prototype to mass production, “not unlike the processes that are used in the semiconductor or consumer electronics world,” Lawson explained. The company has been making progress on its component development goals since the beginning of the year, he told me, and expects to announce the successful demonstration of a few of these milestones in the coming months. Lawson ultimately expects Inertia to complete the core components of its laser and target manufacturing systems by the middle of next year.
The team will spend the next two to three years integrating these individual pieces into two fully operational subsystems, a prototype laser system and a target manufacturing line. Around 2030, the company will begin combining those subsystems into a first-of-a-kind fusion power plant, which will also serve as the proving ground for the target chamber, tritium fuel breeding system, and power conversion system that turns fusion heat into electricity. By the middle of the next decade, Inertia aims to be generating power from this first plant, setting the stage for the company to build and connect additional grid-scale commercial power plants.
There are plenty of engineering trade-offs that the company will have to solve for. Take the decision around how to size the target chamber, for example. “If you make it bigger, your walls have an easier time and survive longer, but it’s more expensive. If you make it smaller, your walls have a tougher time because they’re closer to all the heat and energy that the fusion reaction is creating, but now your power plant costs less to build.”
But to Lawson, this represents exactly the type of problem Inertia was built to solve: complex engineering issues that come to the fore once scientists have demonstrated the fundamental physics are sound. He thinks other fusion companies may someday reach this stage, as well — though he’s unwilling to hazard a guess on exactly what approach or startup is best positioned to do so.
“There have been generations of scientists who’ve made their predictions about fusion energy and gotten it wrong,” he told me. “I’m not going to pretend to be smarter than them. All I’m here to say is, just knowing that one did work, we can commercialize it.”