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Avalanche raises $40M to pursue vision of tiny nuclear fusion reactor

The startup is spurning room-sized reactors in favor of a small, modular design. But it’s unclear when or if fusion technology — large or small — will pan out.
By Eric Wesoff

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Close-up shot of Avalanche engineer working on the company's small fusion reactor
(Avalanche Energy)

Avalanche Energy, a small startup building a small nuclear fusion reactor, just notched a technical milestone that might bring this elusive technology closer to the commercial generation of low-carbon power. The company also announced that it closed a $40 million venture round — no mean feat in a harrowing fundraising environment for high-risk hardware entrepreneurs.

During the 70 years that scientists have attempted to harness the awesome power of the fusion reaction, they’ve mostly built machines called tokamaks that tend toward cathedral size. Equipped with giant lasers or massive magnets, this Brobdingnagian equipment comes with a cathedral-size price tag. 

By going small, Seattle-based Avalanche is aiming for a capital-efficient, downsized approach to generating commercial power from fusion. Importantly, the reactor’s desktop” size enables fast development cycles at relatively low cost compared to the behemoth fusion devices other companies are constructing and testing.

Despite a scientific breakthrough late last year at the National Ignition Facility, even the most optimistic fusion fans say the tech is many years — if not decades — away from generating commercial power. 

But a long and uncertain path to success hasn’t stopped top-tier venture investors, celebrities and the billionaire class from transferring close to $5 billion of society’s capital into fusion companies over the last few years. As Canary has reported, startups such as Commonwealth Fusion, General Fusion, Helion Energy, TAE Technologies and Zap Energy have raised astounding sums, some in billion-dollar rounds, from investors including Sam Altman, Jeff Bezos, John Doerr, Bill Gates and George Soros, all pursuing a high-risk, high-reward technology.

The co-founders of Avalanche, CEO Robin Langtry and Chief Operating Officer Brian Riordan, both worked at Bezos’ space exploration company Blue Origin for years. Langtry told Canary Media that the modular nature of Avalanche’s prototype lends itself to the new space” rocket-design ethos of fast-to-test” and test-fail-fix” — most recently on display last week with the explosion of a rocket from Elon Musk’s SpaceX. 

And while fusion is hard, so is closing a $40 million funding round in uncertain times. Langtry said that raising money in the summer and fall of 2022 was not easy. He said the new investment provides enough runway to get to 2025 and make a lot of progress along the way,” as the company aims to grow its headcount from 25 to 45

Existing investor Chris Sacca’s Lowercarbon Capital led the round along with Peter Thiel’s Founders Fund and Toyota Ventures. This Series A follows the company’s $5 million seed round in 2021, led by Azolla Ventures along with Congruent Ventures and Lowercarbon Capital. (Sacca’s firm has a $250 million fund dedicated to fusion investments.)

Fun with fusion

To achieve fusion, hydrogen must be converted into plasma, a transformation that requires million-degree temperatures, much hotter than the core of the sun. In the medium of the plasma, negatively charged electrons separate from positively charged atomic nuclei.

Fusion machines 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 energy that scientists dream of harvesting to do things like drive a conventional turbine. 

The holy grail for the fusion entrepreneur is a process that creates more energy than is needed to power it, also called net energy or positive output. A number of deep-tech startups are inching closer to this dream of prodigious energy at low cost. But right now, more energy is required to catalyze fusion than results from the process — a lot more. 

Many fusion startups use magnetic confinement of the plasma, where the plasma is stabilized by massive magnets and heated to extraordinary temperatures so the nuclei can fuse. Instead of magnets, Avalanche’s electrostatic approach relies on very high voltages. The startup’s prototype uses electrostatic fields to trap ions, while also employing a magnetron electron confinement technique to reach higher ion densities and increase the incidence of fusion reactions. If Avalanche can get the voltages and ion densities optimized, the resulting fusion reaction will produce neutrons that can be transformed into heat.

That’s a big if. But this week, the company said it made significant progress on one piece of the puzzle.

For us, the metric is voltage, and we need to get to 300 kilovolts to get to the optimum fusion energy in our device. We hit 200 kilovolts in our lab, which is a big deal — getting that much voltage into a 12-centimeter-diameter tube,” said Langtry.

The next big milestone we’re hopefully announcing in a year or two is that we are able to densify this plasma not only at the right energy but at densities where it’s interesting for energy generation,” he added. We’ve got a lot of work to do.”

The company emphasizes that its reactor’s component parts are already commercially available: Its magnetron is a variation of a microwave-oven component, and its electrostatic base technology is a derivative of another existing product.

Riordan contends that Avalanche’s small scale differentiates it from other larger players in the space. The company doesn’t need $1 billion to make progress; it can do a lot with millions.

He said the company will initially focus on hard-to-decarbonize sectors and niche uses of its tech. We’re not trying to do grid-scale energy,” Riordan told Canary last year. There’s a whole realm of industries that need to be decarbonized: long-distance trucking, aviation, maritime — huge carbon sources.”

As cost comes down, markets will open up, said Langtry. 

We do think space and defense is probably the first application for what we’re trying to do,” said the CEO

Eric Wesoff is editorial director at Canary Media.