This tiny fusion reactor is made out of commercially available parts

Nuclear startup Avalanche Energy has modest funding, a skeleton crew, a pocket-sized prototype — and grand ambitions.

A cylinder made out of metal and glass
Avalanche's small-scale fusion reactor prototype (Avalanche Energy)
  • Link copied to clipboard

For more than 70 years, governments, oil and gas companies, and entrepreneurs have dreamed of harvesting energy from the nuclear fusion reaction. But while nuclear fission plants have been providing electricity around the world since the 1950s, nuclear fusion has never come to fruition.

Nevertheless, fusion has been having its moment of late. A year ago, Canary Media reported that scores of VCs, billionaires and celebrities had become smitten with fusion energy and were spending money like drunken fusion scientists on an energy source that still exists only in science-fiction novels. 

Since then, the trend has only accelerated. More than $4 billion in private capital has flowed into fusion research in the last few years.

Subscribe to receive Canary's latest news

One of the beneficiaries of this bonanza, Avalanche Energy, is hoping to succeed where others have failed with a capital-efficient, downsized approach to generating electricity from fusion. The Seattle-based fusion energy startup plans to use an unconventional electrostatic technique to scale its modular fusion cell down to the size of a fire extinguisher.

Getting small

To achieve fusion, hydrogen must be converted into plasma, a transformation that requires million-degree temperatures, much hotter than even 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 problem is that more energy is required to catalyze fusion than results from the process — a lot more. The holy grail everyone is seeking is a process that creates more energy than is needed to power it, also called net energy or positive output. 

A lot of the fusion teams making a run at this most difficult of physics problems work on a grand scale that requires giant lasers or massive magnets made of exotic materials, not to mention sky-high stacks of cash and plenty of personnel. Magnetic confinement devices such as tokamaks require major real estate — Europe’s International Thermonuclear Experimental Reactor project takes up nearly 450 acres. 

In sharp contrast, Avalanche’s small-scale modular approach is more akin to Tesla’s electric-vehicle battery design, co-founder and CEO Robin Langtry told Canary Media in an interview. It’s hundreds of little cells that we can mass-produce in a giga-fusion factory. You might need a few of them for a car, a dozen for a bus, maybe 100 for an airplane.”

Man in coat and knitted beanie stands at a work table strewn with mechanical devices and cords
Honey, I shrunk the tokamak: An employee tests Avalanche's small-scale fusion reactor prototype. (Avalanche Energy)

Langtry and Avalanche’s other co-founder, Chief Operating Officer Brian Riordan, both worked at Jeff Bezos’ space exploration company Blue Origin for years. As Langtry put it, they were working on some of the early architecture stuff for Mr. Bezos,” then decided to focus on something a little closer to Earth.” (Although it’s notable that Avalanche did just receive a grant from the Defense Innovation Unit for a prototype of a fusion engine to be used for space propulsion.)

What we love about new space’ — it’s really fast to test,” said Riordan, who wants to apply that fast-to-test design principle to the development of nuclear fusion. The small size, modular nature and somewhat less exotic architecture of Avalanche’s prototype lend themselves to this process. 

Historically, a fusion experiment took years, if not decades, and billions of dollars to set up, but Avalanche can run real-world experiments a few times per week on single-digit millions” of dollars, according to Clay Dumas, general partner at Lowercarbon Capital and an investor in Avalanche.

Instead of relying on massive superconducting magnets, Avalanche Energy’s prototype employs electrostatic fields to trap fusion ions, while also employing a magnetron electron confinement technique to reach higher ion densities. The resulting fusion reaction produces neutrons that can be transformed into heat.

The magnetron used by the startup is a variation of a device found in everyday microwave ovens” that enables the densities and cross sections necessary for fusion,” according to Avalanche investor Joshua Posamentier, a managing partner at Congruent Ventures.

Riordan told Canary, This configuration didn’t have giant lasers and giant magnets, and its physics didn’t want to be in a form factor larger than a fire extinguisher. [It’s] the right form factor for scalability, rapid build, test, fix and iteration on tight development cycles. We wanted to do a small reactor because we thought that was the path to scale.” 

The goal is to actually build one of these things,” Langtry says. The first step is funding a small team to build a tiny fusion reactor at a really fast pace. Avalanche anticipates that the proposed modular fusion cell, which will have a diameter of approximately 5 inches, will produce 5 to 15 kilowatts of power. 

The company emphasizes that its magnetron is a variation of an everyday device and that the electrostatic base technology is a derivative of a product available from ThermoFisher Scientific, which is widely deployed for use in commercial mass spectrometry. We’re taking two devices that exist already, things you can buy commercially for various applications,” Langtry said. We’re just putting them together in a new interesting way at much higher voltages” to build a recirculating beam fusion” prototype. 

Big bucks for fusion

Avalanche has received a relatively modest $5 million in venture funding in a round led by Azolla Ventures along with Congruent Ventures and Chris Sacca’s Lowercarbon Capital — a mere drop in the cash tsunami that’s flowing into nuclear fusion technology these days. The startup is competing with some much bigger, deep-pocketed players building cathedral-scale fusion prototypes.

Commonwealth Fusion Systems’ variation of magnetic confinement fusion technology won an epic $1.8 billion round late last year led by Tiger Global Management along with a crowd of investors including John Doerr and Bill Gates. Last year, Commonwealth built and demonstrated high-temperature superconducting magnets that it claims are the strongest of their kind and represent a key technological milestone in commercializing fusion energy. 

TAE Technologies has raised more than $880 million from investors including Vulcan, Venrock and Google. TAE’s fusion design shoots beams of plasma into a vessel where they are held in place by a magnetic field. The design shares some properties with particle accelerators.

Helion Energy closed a $500 million Series E fundraising round late last year for its magneto-inertial fusion that combines magnetic fusion and the heating of pulsed inertial fusion. Sam Altman, former president of Y Combinator, led the funding round. Helion’s intent is to convert fusion energy directly into electricity and skip the heat-harvesting step.

Canada’s General Fusion, a developer of magnetized target fusion (a process that also combines magnetic confinement with the compression and heating of inertial confinement), claims that it is developing the fastest, most practical and lowest-cost path to commercial fusion energy.” The company has raised $322 million from investors including Bezos Expeditions.

Zap Energys reactor design compresses plasma with a blast of electric current that creates a magnetic field instead of using expensive magnets to do it. Zap raised $27.5 million in Series B funding in 2021 for its fusion energy technology in a round led by Addition. The company envisions a camper-size fusion reactor providing 200 megawatts of thermal energy. 

Riordan contends that Avalanche’s small scale gives it an advantage over these much larger players. In his view, seeking $5 million to fund a team of 15 to prove out some fundamental physics is a lot better than asking, Can you give me $1.5 billion to build a tokamak?”

Aggressive claims from fusion CEOs

Fusion startup CEOs have provided a litany of aggressive claims about how quickly their companies are going to bring commercial fusion to market, with timeframes ranging from a few years to within the decade. Avalanche’s CEO also promises a compressed go-to-market schedule: We’re not 10 years away. We’re a lot closer than that.”

Avalanche’s design approach could open up new applications for fusion that are not about connecting to the electrical grid. According to Riordan, We’re not trying to do grid-scale energy. There’s a whole realm of industries that need to be decarbonized: long-distance trucking, aviation, maritime — huge carbon sources. Right now, we don’t have great options. We’ve got hydrogen, but the process for making it isn’t necessarily green. We’ve got synthetic fuels. [Avalanche is] going after applications that are hard to decarbonize.”

We have a unique opportunity to make a run at a tiny fusion reactor. Every day, I walk into the office thankful that we have that opportunity, along with this hair-on-fire sense of urgency that this [funding wave] may not last forever.”

Eric Wesoff is the editorial director at Canary Media.