Commonwealth Fusion Systems Raised Another $115 Million to Reach ARC Fusion Commercialization Phase Starting 2025

Commonwealth Fusion Systems (CFS), a startup commercializing fusion energy, has raised $115 million and closed its Series A round. New participants in the round include Future Ventures, Khosla Ventures, Lowercase Capital, Moore Strategic Ventures, Safar Partners, Schooner Capital, and Starlight Ventures who join Eni, Breakthrough Energy Ventures, The Engine and other investors committed to supporting the commercialization of fusion energy. CFS is collaborating with MIT’s Plasma Science and Fusion Center to develop the world’s first net energy gain fusion system, called SPARC.

CFS will produce first-of-its-kind high-temperature superconductor magnets to build smaller and lower-cost fusion power plants. This funding will allow CFS to demonstrate its magnet technology at full scale. CFS in collaboration with MIT’s Plasma Science and Fusion Center will use these magnets to build SPARC by 2025 and demonstrate net energy gain from fusion for the first time in history. SPARC will pave the way for the first commercially viable fusion power plant called ARC, which will produce fusion power onto the grid.

1. Alcator C-Mod: Plasma Performance Basis     Completed
2. HTS Magnets: Enabling Technology            In progress
3. SPARC: Fusion Energy Demonstration          Starting in 2021
4. ARC: Commercialization                      Starting 2025

1. Alcator C-Mod is a compact, high-magnetic field tokamak at MIT that has provided much of the research basis for SPARC. As a result of DOE funded research on Alcator C-Mod the team developed the science that retired key risk in the path toward commercial fusion. The compact configuration enabled our team to rapidly incorporate innovations and provide time sensitive answers to questions surrounding fusion science and technology. In 2016, C-Mod broke its own record for plasma pressure in a magnetically confined device, an important measurement for fusion.

2. A new high temperature superconductor (HTS) recently reached industrial maturity: Rare Earth Barium Copper Oxide (REBCO). CFS is using HTS and building first-of-its-kind high-field large-bore superconducting magnets. HTS magnets will allow for smaller, faster, and less expensive tokamaks using the science developed on Alcator C-Mod and other tokamaks.

3. Commonwealth Fusion Systems is collaborating with MIT’s Plasma Science and Fusion Center to build SPARC, the world’s first fusion device that produces plasmas which generate more energy than they consume, becoming the first net-energy fusion machine. SPARC will the pave the way for carbon-free, safe, limitless, fusion power. This compact, high-field tokamak will be built with HTS magnets, allowing for a smaller device than previous magnet technology. SPARC is an important step to accelerate the development of commercial fusion energy.

4. Following the SPARC demonstration, CFS will construct the world’s first fusion power plant, ARC. ARC will produce fusion power onto the grid and demonstrate the science and technology required for economically competitive, mass production of fusion power. It will pave the way for fusion systems that will provide carbon-free, safe, limitless power for the world.

26 thoughts on “Commonwealth Fusion Systems Raised Another $115 Million to Reach ARC Fusion Commercialization Phase Starting 2025”

  1. Of course there’s neutron insulation: It’s called “matter”. If your reactor is surrounded by a blanket of material, then fast neutrons slow down by elastic scattering with the nuclei in the blanket, and are eventually captured by one of them. The current thinking is that if you put a lot of Li-6 and -7 in the blanket, the bulk of the neutrons will be captured to breed more tritium.

    As for your “100% radioactive” statement, I don’t even know where to begin. Does this mean that every nucleus in the reactor is unstable? That’s clearly ridiculous.

    Yes, there will be some neutron activation of parts of the reactor vessel. Yes, it will have to be disposed of. But neutron-activated steel is only medium-level waste, and we’re talking about a very small amount.

    Tritium release from a fusion plant is a real problem, and will require a real solution. But it’s no greater a problem than it is from an ordinary fission nuke, where it’s regarded as completely manageable. Beyond that, a 500 MW fusion plant will use about 38 g of tritium per day, so the on-site inventory won’t be a lot more than that, and most of it will be in solution in the blanket. There’s just not much to release.

    I respect Hirsch’s opinion, and he’s right that there are definitely challenges with tokamaks. However, you should bear in mind that Hirsch is one of the inventors of inertial-electrostatic confinement fusion; he has a dog in this fight, even if it’s so far a feeble, three-legged dog.

  2. Best sf novel ever written is “Three to conquer” by Eric Frank Russell
    I replied here because that page is not working, at least for me.
    I bet you won’t disagree.

  3. Trouble with water is low temperature phase transition into gas, which is the main deficiency of water-cooled and moderated fission reactors. Then there is radiolysis, which makes a hydrogen-oxigen mix so prone to making a fairly large bang – a most unfortunate development inside a pressure vessel with a nuclear reaction in it. Then there is a 2.23MeV gamma that so predictably comes out of a newly made deuteron, probably gets absorbed by water only to intensify radiolysis and phase transition. A few such things turn magic into mehgic.

  4. Nice try. You compared a large dense core filled with neutron moderator and absorbers (burnable poisons), with a vacuum vessel filled with a wiff of gas.

  5. First. When reaction generates hundreds of MW in fast neutrons, neutrons will escape – there is no such thing as neutron insulation.
    Second. If something goes wrong, or if nothing goes wrong at all, the entire apparatus will be 100% radioactive after a prolonged operation, as neutrons will activate all of its structures completely. All structural materials will absorb neutrons, isomers will form, spallation will generate radioactive isotopes, tritium will spread throughout. There will be no “mildly”, it will be “hot” and unapproachable for a long time. That is why D-T tokamac is a road to nowhere, as Hirsch pointed out long ago.

  6. First, SPARC is a research/proof-of-concept reactor. An actual commercial reactor would be more like the larger ARC, which would generate about 500 MWe.

    Second, fusion reactors don’t let their neutrons escape. The neutrons are what generates the heat to run the steam plant. Beyond that, the working fluid will likely be a lithium salt, which will use the neutrons to breed more tritium.

    Remember, this is fusion. If something goes wrong, no more neutrons are generated. The long-term radioactive components are the tritium (half-life about 12 years) and a variety of mildly neutron-activated metals once the machine has reached its useful life. That’s a tiny amount of medium-level waste.

  7. The trouble with cheap fusion prototypes is they don’t make any power. Mind you, that’s also the case with expensive fusion prototypes…

  8. There was a scene like that in, IIRC, The Man with a Golden Gun. But I suspect that they copied their movie set from earlier fusion research stuff, which has been looking like this since the 1950s.
    (Said copying via the Prof Eric Laithwaite team at University of London who I know did at least some of the fancy special effects for Bond films.)

  9. It should be noted that SPARC is kind of a hack: It doesn’t have the modular, serviceable design, doesn’t have a functional blanket, and is likely good for only a few thousand shots before neutron embrittlement gets so bad that it has to be retired. The “SP” stands for “shortest possible”: they want to demonstrate Q>about 5 as quickly as possible, and that’s it. The idea is that a demo of better than breakeven will be enough to attract massive amounts of capital to start building ARCs.

    There are a handful of problems without good engineering solutions for a full-scale ARC. Probably the biggest issue is the divertor, which removes the helium “ash” from the plasma. These are pretty much a low-readiness technology for all tokamaks.

  10. An interesting aspect is that its not so much the critical field of the superconductor that limits the strength of the magnet but the mechanical structure of both the tapes and the magnets. That is why the REBCO is on the back of a thin stainless steel tape (for mechanical strength).

    I really hope that they will not be satisfied with the current REBCO magnet maximum magnetic field, but will continue to optimize the critical field and the mechanical strength. If they will reach a factor of 2.5 instead of 2.0, they would gain efficiency. They are already at the point where the kinetic probability of fusion forces the volume to be larger than the 1/B^4 scaling would otherwise allow them to achieve, but they could keep the small volume and go for higher Q-values.

  11. This is actually a really, really good idea and it’s about time they finally started. The necessary plasma volume scales as 1/B^4 and the REBCO tapes can produce twice as strong magnets as the conventional superconductors. This results in a plasma volume that is 16 times smaller. 16.

    But it doesn’t stop there. The MIT guys have figured out how to make the reactor modular in such a way that you lift of the “top” of the reactor for easy access. They achieve this bu adding a thick “bridge” between the different superconducting segments that consists of a normal conductor. This way, inspection and updates are made orders of magnitude less laborious. Brilliant!

  12. Brian,
    I am nearly certain that the picture you are leading with is a slightly doctored still from a James Bond movie. Is that deliberate?

  13. No clear references, but it appears to be another attempt at D-T fusion, as follows from “conservative physics” reference. So what if they succeed? That would be a device making 10s pulses at ~87MW power level – all that in pulses of 14MeV neutrons. How does that translate into “scalling to power generation” is not disclosed. Must be seriously black magic. Even if it is less conservative D-D, it is still tens of MW in pulsed neutron flux. They would not be permitted to operate such a thing anywhere near cities, as it will activate everything around it: air, water (will need some cooling), structures, dust, and any personnel.

  14. A decade or so ago I remember reading an article about using non-superconducting magnet for a fusion reactor prototype due to the much lower cost.


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