Our Fusion Portfolio: “Strong to Quite Strong”

Just ask the DOE.

Midjourney’s interpretation of what a fusion powerplant in a solarpunk industrial park will look like.

Uncle Joe’s debt ceiling deal isn’t the only BFD that came out of D.C. this week. The Department of Energy just announced $46 million in awards to help eight fusion companies build their first power plants. This drives home how quickly fusion is going from sci-fi to steel-in-the-ground. That might come as a surprise to some, but not here in our shop.

We are proud to say that the four eligible fusion companies Lowercarbon has backed were all selected for these grants: Commonwealth, Princeton Stellarators, Xcimer, and Zap. Collectively, they earned 70% of DOE’s funding. Congratulations to them, as well as the other teams that made the cut. It was a historic day for the field.

The titles of government press releases can strike a mundane note, but as you dig into this one it’s clear we’ve just passed a major benchmark in the Biden Administration’s 10-year plan for commercial fusion. An independent panel of experts doled out tens of millions of dollars to companies that are on course to generating the electrons that charge every aspect of our lives. A bipartisan mix of Congress people are taking credit. The Secretary of Energy herself declared commercial fusion is inevitable. More funding and support is a foregone conclusion.

There are no silver (or nickel or lithium or cobalt) bullets when it comes to solving global warming. But give us cheap, around-the-clock, zero-carbon power that isn’t constrained by fuel availability and that would definitely make the job easier. Not to mention the countless other ways that fusion holds the potential to broaden economic opportunity, beefs up national security, and generally brings humanity into better alignment with our host planet. Btw, did we mention that the teams who succeed may become some of the most valuable companies of all time? 

These are some of the reasons why, last year, Lowercarbon raised a $250m fund to back the leading fusion companies around the world. We called it “Q>1” for the ratio representing net energy gain from fusion. No doubt some people were quick to bust our chops and dismissed fusion as a folly. We get it. No one should have illusions about the daunting challenges of commercializing fusion. Yet, as we wrote in our fusion fund announcement last year:

It’s no longer a matter of if this will happen, it’s about when, and when is sooner than you think. The science of fusion is no longer a pipe dream. For many approaches, the physics is (mostly) understood, and the focus is upon building the reactors, scaling up the power banks, and engineering solutions to harness the energy generated. Q>1 has shifted from hope to an inevitability. This milestone, when achieved and published, will dramatically accelerate flows of talent, capital, and attention into the industry.

That was in October. Only a couple months later, the team at NIF announced scientific breakeven, following a laser shot that produced a Q value approaching 1.5 (meaning the fusion reaction generated nearly 50% more energy than it consumed). Is it ok to admit this news left us with some shit-eating grins?

Now, with the DOE launching the Milestone-based Fusion Development Program, major advances in artificial intelligence juicing R&D, and the world’s largest investors jumping into the space, the advantages of a portfolio strategy in fusion are shining through. The DOE itself is taking the same approach, and their strategy happens to share plenty of themes with ours: a balance of tokamaks, stellarators, lasers, and alternative approaches. 

The hurdles facing any individual company are high, but the upside of even just one succeeding is bonkers. So we’re investing in fusion as a sector with the ambition and resources to accelerate the most promising teams. The startups we’ve had the privilege to partner with are pursuing distinct technical pathways, with uncorrelated science risks, varying timelines, and diverse capital needs:

Commonwealth Fusion Systems: Tokamak fusion with plasma-taming magnets.

Perhaps the best-understood approach to fusion is the tokamak, a donut-shaped reactor that confines plasma using large and powerful magnets. And, CFS is the world’s leading tokamak company. Historically, the biggest challenge is that the magnets powerful enough to confine plasma needed to be enormous, such that building a single reactor would set you back tens of billions of dollars. Commonwealth’s core technological breakthrough lies in their high-temperature superconducting (HTS) magnets that pack a lot more punch into a compact size. In 2021, they demonstrated that their magnets are capable of producing a 20 tesla magnetic field, the most powerful man-made magnetic field, ever. Then, earlier this year, CFS broke ground on a reactor that, when completed in 2025, is expected to exceed a fusion energy gain factor of Q=1. From that point, we will still be a few years away from fusion electricity being fed into a utility grid, but we will have line of sight on a multi-hundred-megawatt Commonwealth reactor capable of powering a small American city.

Princeton Stellarators: Stellarator fusion from planar magnets.

Stellarators are one of the earliest fusion reactor designs, dating back to the seminal work of Lyman Spitzer at Princeton in the early 1950s. The promise of stellarators is greater plasma stability and energy efficiency than tokamaks, but historically they failed to gain traction because the complexity of manufacturing their mangled-magnet reactors made them nearly impossible to build or test using traditional manufacturing techniques. In the last few years, all that has changed. Recent advances in simulation models and manufacturing of high-temperature superconducting magnets are converging to simplify stellarator modeling, building, and operating. On the public stage, this has been validated by test runs at Germany’s Wendelstein 7-X experimental reactor. In private, there are an emerging crop of stellarator approaches that are pursuing compelling paths to commercialization. Princeton Stellarators are bringing it all back home to where it started with the simplest stellarator design imaginable.

Xcimer: Inertial fusion from frickin’ laser beams. 

Xcimer leverages advances in inertial fusion energy and specifically in excimer gas lasers (used in photolithography and for LASIK eye operations) to create scalable laser-driven fusion systems. It works by generating ultra-intense pulses of light to first compress, then heat, and ultimately ignite capsules of fusion fuel small enough to hold between your thumb and forefinger (although you wouldn’t want to be anywhere near the reaction, because the temperatures exceed 100 million degrees Celsius). The chamber surrounding the fuel capsules will safely absorb the energy generated by the fusion reaction as heat, however, transforming it into practical forms of power from steam for industrial processes to electricity for commercial and consumer use. Xcimer’s laser architecture is able to provide light at 100x lower cost per unit of energy and up to 10x more energy than the National Ignition Facility laser that achieved Q>1 in December 2022.

Zap Energy: Magnetless fusion with sheared flow Z-pinch confinement.

While the most heavily researched fusion reactor configurations use magnets and lasers to confine plasma, it is not the only way to go. If you could scrap those elements altogether, the resulting reactors could be smaller, cheaper, and more modular. This is precisely what Zap is working on. They are developing what’s known as a sheared flow Z-Pinch technology that uses high electrical currents to generate a magnetic field around plasma to compress it. “Sheared flow” refers to plasma flowing at alternating velocities and radii, concepts that are beyond the scope of this humble blog post but if peer reviewed physics papers make your heart race: knock yourself out. As current goes up, so does pressure and density in the plasma. The Z-pinch results in a dense, high-temperature, reactive medium that can be confined long enough for fusion reactions to occur. The heat produced from the reaction is harnessed in a liquid metal wall and drives electricity production. What Zap’s technology unlocks are compact reactors producing 50 megawatts of power that could be fed into a grid or reserved for directly powering heavy industrial applications.

(There’s even more fusion wildness where this comes from: check out what the teams at Avalanche and Renaissance are getting up to.)

Feeling fusion-curious? Don’t be ashamed. There’s nothing wrong with giving into the sense of hope that energy can be clean, cheap, inexhaustible, and fossil-free. For most of the past seventy years, it was admittedly hard to see how we would harness the same reactions that light up our solar system. We were on the long, seemingly flat part of the curve. But, today, the unavoidable reality is that it’s working. Progress in fusion reactor design is outstripping even semiconductors. Private investment begets government dollars begets more funding. Technical breakthroughs are daily occurrences and one of the world’s largest companies has already signed a purchase commitment to buy fusion power. The innovation curve is bending to vertical. So go ahead and let your mind wander. What would you do with dense, dispatchable, 24/7 power? If you aren’t asking this question yet, now is the time. 


Clay & Clea

p.s. If reading about smashing together hydrogen isotopes gets you fired up, we have more good news: all the companies mentioned above are hiring. So Get Off the Couch and check out countless opportunities to make a direct impact on one of the most exciting ways to zero out emissions and expand the horizons of our species.