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Nuclear fusion startup Xcimer raises $100M to chase laser-based power

The lure of fusion’s awesome energy potential continues to draw interest from entrepreneurs and investors alike — despite the tech being far from viability.
By Eric Wesoff

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The preamplifier at the Lawrence Livermore National Laboratory's National Ignition Facility. (Xcimer)

Xcimer Energy has raised $100 million to turn nuclear fusion, the source of the sun’s immense energy, into a viable way to power our planet’s electrical grid.

The Denver-based startup’s ambitious goal is to develop some of the mightiest laser beams on earth in order to unleash the atomic dance of the fusion reaction, while controlling the reaction well enough to channel its energy into abundant, always-on, low-cost, carbon-free power.

Xcimer’s series A financing round was led by Hedosophia, along with investors including Breakthrough Energy, Lowercarbon Capital, Prelude Ventures, Emerson Collective, Gigascale Capital, and Starlight Ventures. The startup raised a $2.5 million seed round in 2022 and received a $9 million award from the U.S. Department of Energy’s Milestone-Based Fusion Development Program.

Other startups such as Avalanche Energy, Commonwealth Fusion, General Fusion, Helion Energy, TAE Technologies, and Zap Energy have also raised jaw-dropping rounds from investors including Jeff Bezos, George Soros, and Peter Thiel — all betting on a high-risk chain of scientific breakthroughs. The Fusion Industry Association lists more than 40 private fusion companies working in the revenue-free field, which has raised a total of $6.2 billion of capital over the past few years. Investor Chris Sacca’s climate investment firm, Lowercarbon Capital, has a $250 million fund devoted solely to fusion investing.

Several of these startups, including Sam Altman–backed Helion Energy, claim they will begin delivering power within the decade, despite the fact that no nuclear fusion reactor has yet done so.

This growing fleet of fusion startups is pursuing a variety of technological approaches, such as using magnetic confinement or extremely high voltages or currents to confine the plasma.

To achieve the fusion reaction, hydrogen must be converted into plasma, a state of matter in which negatively charged electrons separate from positively charged atomic nuclei in a sort of atomic particle soup. The transformation to plasma requires temperatures on the order of one million degrees.

Fusion machines then compress and confine the plasma in order to push the freed-up nuclei so close together that they overcome repellant electrostatic forces and ultimately fuse. This process releases neutrons, and it’s this neutron energy that entrepreneurs dream of harvesting to do things like spin a conventional turbine.

Xcimer, for its part, is betting on lasers to do the job — specifically excimer lasers.

Called inertial confinement fusion,” this approach is the same one used by Lawrence Livermore National Laboratory’s National Ignition Facility (NIF) in a 2022 scientific breakthrough. The experiment provided the first-ever evidence of what’s been one of the holy grails of fusion science: achieving a net energy gain in a fusion reaction. Put simply, the NIF experiment got more energy out of a fusion reaction than the energy it put into the reaction. (This is not the same as net energy positive; right now, a lot more energy is required overall to initiate fusion than is generated by the fusion reaction itself.)

NIF hit this milestone by focusing 192 science-fiction-size laser beams onto a fuel target the size of a pearl for a few billionths of a second, igniting the pellet and creating a contained plasma reaction. The cost to develop and build the ignition facility was about $3.5 billion, according to the lab.

Commercialization will require much stronger lasers at much lower costs. Not coincidentally, that’s what Xcimer says it will do.

In a press release, the company states that its laser architecture will scale to up to 10 times higher laser energy, 10 times higher efficiency, and over 30 times lower cost per joule of laser energy” than the NIF experiment. The startup claims to be leveraging high-energy laser technologies originally developed for the (expensive and less than successful) Strategic Defense Initiative defense programs of the 1980s, known derisively as Star Wars.”

Even if the science of nuclear fusion can be refined — a big if — companies like Xcimer will still face an enormous set of financial, engineering, and safety challenges in turning nuclear fusion into a true asset to the power grid.

Eric Wesoff is editorial director at Canary Media.