Connor Galloway and Alexander Varis have been following developments in nuclear fusion research since they were roommates at MIT nearly 20 years ago. For much of that time, nuclear fusion wasn't a particularly exciting hobby. Breakthroughs were few and far between, and commercial fusion always seemed elusive, still 20 years away from providing cheap, inexhaustible, pollution-free electricity.
But in August 2021, the pair saw news that suggested fusion power might finally be within reach: Scientists working on a particular type of fusion at the National Ignition Facility (NIF) had doubled their previous best results.
Though it got little attention in the mainstream media, Galloway and Vallis knew this was a turning point. “It was one of those pivotal moments, where it was like, OK, now is the time,” Vallis told TechCrunch.
Spurred to action, Galloway began drawing up plans for the startup he founded, Eximer Energy, in January 2022. Vallis joined the company in April that year, and the two have been quietly working with their teams ever since to come up with a plan for a fusion power plant that they believe has the best chance of providing commercial-scale electricity.
“The type of inertial fusion we're pursuing is the most economical in the long term,” Galloway said.
Eximer is pursuing a technology called inertial confinement fusion, the same type used by NIF, which in December 2022 demonstrated that controlled fusion can generate more than the power needed to start a reaction. Inertial confinement involves shining a laser at a tiny fuel pellet, compressing and heating it until deuterium and tritium atoms begin to fuse together, releasing vast amounts of energy in the process.
But Xcimer has undertaken what could be described as a fundamental redesign of the underlying technology.
It starts with the laser. Xcimer's design is newer and promises to be more powerful: NIF's system maxes out at about 2 megajoules of power, while the startup is targeting 10 megajoules for a commercial-scale design. What's more, Xcimer's design should be significantly cheaper to build and operate. In principle, it's similar to those used for years in semiconductor manufacturing, and the method of focusing laser beams is based on research done as part of the 1980s Strategic Defense Initiative (also known as Star Wars).
While many inertial confinement proposals suggest using a laser to fire several fuel pellets per second, Galloway said Eximer plans to fire one fuel pellet every few seconds.
The inside of Eximer's reactor also looks a little different. Instead of a steel-walled reactor, the fusion explosion takes place inside a waterfall of molten salt. The falling salt absorbs the energy of the reaction and creates steam that powers turbines. The hellishly roaring waterfall has the happy side effect of protecting the reactor's walls from damage, a major concern with other designs. “We'll never have to replace the first wall over the life of the reactor,” Galloway says. “One chamber will last 30 years.”
Though only two years old, Eximer has a 10-year timeline to deliver a pilot plant that will prove its commercial-scale ambitions are not just theoretical.
Over the next two years, the company plans to build a demo-scale version of its laser system, which it calls Phoenix, that won't reach 10 megajoules but will be close enough to prove cost savings, Vallis said.
To get through this phase, Xcimer has raised $100 million in Series A funding, the company told TechCrunch exclusively. The round was led by Hedosophia, with participation from Breakthrough Energy Ventures, Emerson Collective, Gigascale Capital, Lowercarbon Capital, Prelude Ventures and Starlight Ventures. The startup also received a $9 million milestone-based grant from the Department of Energy.
“This provides a demonstration of this entire prototype laser system, as well as technology development goals and a roadmap for the rest of the plant,” Valys said. “This is more than enough for the initial phase of DOE's Milestones program.”
The two friends are confident their 10-year plan will work. “It's proven science,” Galloway says. “It's just a matter of making a laser that's big enough, cheap enough, and efficient enough.”