Exclusive: Inertia Announces a New Fusion Milestone

Less than two months after publicizing its roadmap to commercial fusion, Inertia Enterprises has checked step one off its list. The startup ran a simulation demonstrating that its first commercial facility will be capable of producing over 25 times more fusion energy than the laser energy put into it, Inertia told Heatmap exclusively.

This is actually the second milestone Inertia has achieved on its 10-point roadmap to building a grid-scale power plant by the mid-2030s — the startup announced last month that it had cut the manufacturing time for its fusion fuel pellets from days to minutes. But for the lay fusion observer, this latest achievement may be the more striking of the two. So far, the only entity to achieve breakeven — the point at which a fusion reaction produces more energy than it consumes — is Lawrence Livermore National Lab’s National Ignition Facility.

Inertia, founded last year by current and former Lawrence Livermore scientists, is now building on that result under a formal research partnership with the lab, using the same technical approach as NIF: firing high-powered lasers at a tiny pellet of fusion fuel, compressing it until the nuclei fuse and release enormous amounts of energy.

The new results, which Inertia said it’s submitting for peer review, demonstrate that the company’s first commercial-scale plant ought to generate over 250 megawatts of electricity for the grid. But because the startup’s machine has yet to be built, the projected energy gain and power output come from a so-called “virtual shot,” a high-fidelity computer simulation that uses the same design codes Lawrence Livermore has used for its own successful ignition experiments, and is thus calibrated and benchmarked against real results.

“We are simulating all the things that we know happen in a fusion experiment, and it’s using the validated models — the best, highest-fidelity physics models that have been validated to NIF ignition experiments — to project where we will be with Inertia,” the startup’s co-founder, Annie Kritcher, told me. The simulation accounts for factors such as “target defects, variations in laser performance, laser delivery, [and] injection tolerances,” she explained.

Even when variables like these fluctuate, Kritcher said, the machine’s energy yield should barely change. That sets Inertia’s system apart from NIF’s, which operates right on the so-called “ignition cliff,” where small imperfections in the fusion fuel target or slight variations in laser performance can determine whether the system achieves ignition at all. But because Inertia designed its system to operate far above that threshold, minor flaws should translate only to modest dips in performance.

Other fusion startups have run simulations demonstrating the validity of their underlying physics and — in industry leader Commonwealth Fusion Systems’ case — even projecting their ability to exceed breakeven. But Kritcher argues that Inertia’s “virtual shot” is a more meaningful achievement because the startup’s plant design replicates the underlying physics validated by NIF, the only fusion experiment yet to cross breakeven in the real world. “The extrapolation risk for the other validation simulations is much, much, much higher,” she told me.

Kritcher has experienced this risk firsthand during her many years running experiments at NIF. When the facility fired its first real shots at ignition in 2011, she was working as a post-doctoral researcher at the national lab, and sincerely believed these early experiments would be a success. But the shots turned out to be “orders of magnitude off” from achieving their goal, thanks to the “unknown unknowns and the physics that weren’t included” in the team’s initial modeling.

Other companies that haven’t yet proven their physics on a real-world machine still face those “unknown unknowns,” she explained, whereas Inertia has been able to unveil and eliminate as many as anyone has yet found. The startup’s plant design is by no means an exact replica of NIF, however. For starters, its fusion targets will be twice as large, and its lasers roughly five times as powerful. The facility will also fire 10 shots per second, compared with NIF’s roughly one shot per week, using thousands of individually adjustable laser beams rather than NIF’s fixed 192. So as is nearly always the case when scaling up, some unknown unknowns likely remain.

But Kritcher is confident that the virtual shot will translate to real world performance — a level of certainty she admittedly hasn’t always had in her decades of nuclear engineering research and practice. In addition to her role at Inertia, Kritcher remains a senior scientist at Lawrence Livermore, where she has led the physics design for NIF’s fusion energy experiments since 2019.

A few years before the lab ultimately achieved breakeven in 2022 — more than a decade after its first attempts — Kritcher was beginning to doubt that they would ever get there. Then, in 2021, NIF reached a breakthrough that went largely unnoticed outside the ranks of dedicated fusion observers: It fired a shot that produced 70% as much fusion energy as the reaction consumed, bringing the facility within striking distance of net energy gain. And while it didn’t reach that threshold, the scientists said the experiment demonstrated ignition — a self-sustaining fusion burn.

The result gave Kritcher assurance that the lab was on the cusp of energy gain. Now, she feels a similar level of confidence that Inertia can translate its simulated 25x energy gain into a real world commercial facility. “The change that we made going from that first ignition result — the 0.7x gain to the [net energy] gain result — that’s the kind of change I feel like we’re making here,” she told me. “It’s working now, and we’re just making it bigger and better.”