Fusion startup Inertia Enterprises has announced a breakthrough that could finally make its fuel pellet production line look less like a bespoke artisanal craft and more like, well, a factory. The company says it has slashed the time needed to manufacture its fuel pellets from several days to just minutes, knocking down one of the 10 barriers standing between it and the first phase of its commercial power plant ambitions.
This advance was by no means a sure thing. Investors handed Inertia $450 million on the promise that it could commercialize technology developed at the National Ignition Facility (NIF), a place where making fuel pellets is less about speed and more about ritualistic patience. At the NIF, a single pellet can take a week or more to produce and costs a small fortune - hardly the recipe for a profitable power plant.
"But when you really double-click on it, you're like, wait a minute, they're only making a handful of them a year," said Jeff Lawson, co-founder and CEO of Inertia, with the air of someone who just realized the emperor has no clothes. "I put on my commercial hat and was like, wait a minute, I know the word for this: Prototypes."
So Inertia set about turning those prototypes into something mass-manufacturable. "That's why we're hiring people from the likes of Apple," Lawson said, presumably envisioning a future where fuel pellets come in sleek, minimalist packaging. "There's a bunch of industrial engineers who are like, 'Alright, I guess I have to go figure out how to make that a billion times over in a factory.'"
But the NIF's fuel pellet is no iPhone. It's a spherical diamond shell containing a thin layer of frozen deuterium and tritium - the hydrogen isotopes that fuel fusion - with a gaseous mix of the same inside. Every layer must be as close to perfectly spherical as humanly (or machine-ly) possible. The pellets are then wrapped in gold casings called hohlraums, which convert laser energy into X-rays that compress the pellet, triggering fusion. Even the tiniest imperfection can ruin the whole show.
Inertia had to speed up the process without abandoning the physics that made the NIF's approach work. "What happens if you try to do it faster?" Lawson mused, as if asking the universe a question. The team had a head start: Annie Kritcher, co-founder and chief scientist, designed the first NIF experiment that produced more power than it consumed.
After several rounds of development, Inertia can now grow the crystals in about 30 minutes - a process that could take a week at the NIF. A single fuel pellet can be made in two to three hours, and the process can be scaled up to industrial levels. The startup worked with the NIF at Lawrence Livermore National Lab, with which it has formed a public-private partnership.
Inertia has a secret weapon, though: its planned laser is four times more powerful than the NIF's current one, meaning it can tolerate more imperfections. "We actually have a lot of margin," Lawson said. "That's our strategy, to oversize our driver, our laser, to give us lots of margin to go play with in every other part of the system."
Speeding up fuel production also reduces the amount of tritium Inertia needs to have on hand at any given time - a good thing, since tritium is radioactive, expensive (about $30,000 per gram), and scarce (only about 25 kilograms exist globally, according to Science). Inertia plans to breed its own tritium using fusion reactions, but it still needs some inventory to get started. And less time making pellets means less tritium sitting around. Inertia expects its full-scale commercial power plant to use 10 fuel pellets every second.
"By reducing the latency of this step, you've made your facility smaller; you've made the whole thing faster, the whole thing more efficient," Lawson said, summarizing the entire pitch in a way that makes you wonder why anyone ever did it the slow way.