14 ms·

Plenty of skepticism in these comments. I've been following CFS for a while and can present a point of view for why this time might be different. Fusion energy

by dfdx 5y ago

Plenty of skepticism in these comments. I've been following CFS for a while and can present a point of view for why this time might be different. Fusion energy was actually making rapid progress in the latter half of the twentieth century, going from almost no power output in the fifties and sixties to a power output equal to 67% of input power with the JET reactor in 1997. By the eighties there was plenty of experimental evidence to describe the relationships between tokamak parameters and power output. Particularly that the gain is proportional to the radius to the power of 1.3 and the magnetic field cubed. The main caveat to this relationship was that we only had magnets that would go up to 5.5 Tesla, which implied we needed a tokamak radius of 6 meters or so in order to produce net energy. Well that 6 meter tokamak was designed in the eighties and is currently under construction. ITER, being so large, costs tens of billions of dollars and requires international collaboration; the size of the project has led to huge budget overruns and long delays. Recently however, there have been significant advances in high-temperature super conductors that can produce magnetic fields large enough that we (theoretically) only need a tokamak with a major radius of about 1.5 meters to produce net gain. This is where SPARC (the tokamak being built by the company in the article) comes in. The general idea is that since we have stronger magnets now, we can make a smaller, and therefore cheaper tokamak quickly. Small tokamaks do have downsides, namely that the heat flux through the walls of the device is so large that it will damage the tokamak. There have been breakthroughs with various divertor designs that can mitigate this, but to the best of my knowledge I'm not sure that CFS has specified their divertor configuration. This was just a short summary of the presentation by Dennis Whyte given here [0]. I do not work in the fusion community. [0] https://www.youtube.com/watch?v=KkpqA8yG9T4 https://www.youtube.com/watch?v=KkpqA8yG9T4

zetalyrae 5y ago
I've always wondered: why exactly is ITER so expensive, and slow? Is the engineering required at such a standard that it should takes decades of planning and construction and tens of billions of dollars? The timeline is so dilated (started in 1988, first plasma planned for 2025!) it feels like the kind of project that's expected to be cancelled from the start. It just doesn't strike me as obvious that reducing the major radius by a few meters would have such a huge impact on cost/timelines.
- LeegleechN 5y ago
  It's just an absolutely giant construction project. The mass and volume of the construction goes as the cube of the major radius of the reactor. Back of the envelope, SPARC is (6/1.5)^3 = 64 times smaller than ITER. The construction budget for SPARC is ~$500M, so ITER being tens of billions is in line.
  - bigyikes 5y ago
    How do projects like LIGO ever get completed? I’m probably totally naive here, but I thought LIGO is physically larger and has many difficult constraints. The LHC comes to mind as well, and that absolutely dwarfs ITER in physical size. What’s the difference? Dealing with heat output? Superconductors are really hard maybe?
    - sbierwagen 5y ago
      LIGO did take decades to construct, like the LHC. According to LIGO's wikipedia article, it was the most expensive project ever funded by the NSF in 1994.
      - neltnerb 5y ago
        LIGO's size is also deceptive, the legs are kilometers long but the design is an L with the important bit being to vibrationally isolate things, maintain dimensional stability, and maintain vacuum. ITER is likely bigger in terms of volume of concrete or actual footprint.
        lambdatronics 5y ago
        Hmm, looks like ITER and LHC both use about the same amount of superconductor: around 500 tons. [0]https://ieeexplore.ieee.org/document/1018583 https://ieeexplore.ieee.org/document/1018583 [1]https://www.iter.org/mach/Magnets https://www.iter.org/mach/Magnets
- jvanderbot 5y ago
causality0 5y ago
Are those calculations of net gain referring to the total energy generated, or the amount we can realistically capture and put to use?
- ncmncm 5y ago
  The amount of this we can realistically put to use is, always and forever, exactly zero. The only useful outcome of any of this work is a generation of plasma-fluid physicists with practical experience. Pray we can find them something useful to do when the whole enterprise finally collapses.
  - liamwire 5y ago
    You keep making these assertions, failing to back them up with anything other than hand-waving in the direction of entirely unrelated programs. You then respond to requests for citations, or even just an elaboration, with the near-verbatim ‘do your own research.’ Chiefly, how does that further the conversation? More pointedly, why should we listen to you? Credentialism in this arena is valid, and what I currently see are multiple subject matter experts, albeit with a bias/incentive towards believing in themselves, versus you. Please substantiate your claims, or word them more carefully as to reflect them being conjecture.
  - Kelteseth 5y ago
    Huh, I heard the same (tinfoil) argument about climate change, that all scientist make up the crisis to keep their jobs/funding.
    - ncmncm 5y ago
      Scientists are not the ones making the big bucks on fusion demonstrator construction. But, obviously, somebody is. Are. Every cent of overrun goes into a pocket. None of it evaporates.
- lambdatronics 5y ago
  You can assume that they're talking about the total generated. They call this the "scientific gain" whereas the "engineering gain" would include all the inefficiencies of the particle beam injectors that put power into the tokamak, and the inefficiency of the steam turbine that makes electrical power from the fusion heat exhaust, and the auxilliary power to run all the pumps, etc. It's generally thought that the "engineering gain" needs to be at least 5, and the "scientific gain" at least 30, for a working reactor. ITER's supposed to hit scientific gain of something like 10-20, which is close.
yboris 5y ago
A march 2019 talk by Dr. Dennis Whyte of MIT working on SPARC https://www.psfc.mit.edu/sparc https://www.psfc.mit.edu/sparc https://www.youtube.com/watch?v=rY6U4wB-oYM https://www.youtube.com/watch?v=rY6U4wB-oYM
mchusma 5y ago
You are right, people who flippantly dismiss fusion just don't understand it. -Fusion has made consistent improvement, roughly in line with expectations for the level of investment (20 years away predictions were considering if we invested massively, which we did not). - Fusion is in theory something that could give us true energy abundance. Want to just desalinate water like crazy? Want to extract gigatons of carbon? Working fusion enables these to happen woth existing technologies. I like to think of solar, batteries, fission, and wind as compelling ways to go mostly carbon free and lower energy costs about 2x over the next 20 years or so. Fusion is what reduces energy cost potentially another 10x, which really changes the game for lots of things. Exciting stuff. Kudos to this team.
- pfdietz 5y ago
  > Fusion is what reduces energy cost potentially another 10x How did you arrive at that conclusion?
  - stjohnswarts 5y ago
    Probably counting in the cost of unlimited global warming and all the damage it will do if we don't stop it, which we won't if current efforts are par for the course.
    - deleted 5y ago
      [deleted]
    - pfdietz 5y ago
      That would make sense if he's comparing only against fossil fuels. But what was written was: > I like to think of solar, batteries, fission, and wind as compelling ways to go mostly carbon free and lower energy costs about 2x over the next 20 years or so. > Fusion is what reduces energy cost potentially another 10x, which really changes the game for lots of things. Exciting stuff. Kudos to this team. If the 10x is from avoiding fossil fuels, why does fusion get that credit, but the other non-fossil sources don't?
ArtWomb 5y ago
Delay in fusion progress seems to mirror HTS design difficulties. A brittle ceramic, in a punishing maelstrom ;) VIPER: an industrially scalable high-current high-temperature superconductor cable https://iopscience.iop.org/article/10.1088/1361-6668/abb8c0 https://iopscience.iop.org/article/10.1088/1361-6668/abb8c0
vmception 5y ago
This is the best synopsis I’ve ever seen about it, but the skepticism comes from the lack of results A whole generation heard about it in school decades ago. Multiple generations by now, even. Its right up there with battery/energy-storage technologies. Headline after headline, enrapturing a newer and newer idealist set of people to quickly become disillusioned. People just get tired of it. But I’m glad to understand whats going on behind the scenes now. I’ll pay attention. Looks like a real sleeper.
tsimionescu 5y ago
There are still fundamental problems with fusion reactors that are unlikely to make them economically viable, or even carbon neutral. Most notably, the extreme temperatures, hydrogen pumping, and high-energy neutron bombardment mean that, even with liquid metal blankets, the reactors will very quickly become brittle, probably not lasting more than a year or two. Since neutron bombardment also turns any material radioactive, not only do you need to tear down your fusion plant (or at least the expensive reactor part of it) every few years, but you have to do it with radiation-resistant robots, as human workers can't get close to the reactor after it's been operating for a while. https://thebulletin.org/fusion-energy-nuclear-fusion/ https://thebulletin.org/fusion-energy-nuclear-fusion/
- dsign 5y ago
  > Since neutron bombardment also turns any material radioactive, not only do you need to tear down your fusion plant (or at least the expensive reactor part of it) every few years, but you have to do it with radiation-resistant robots, as human workers can't get close to the reactor after it's been operating for a while. I bought a new screen cover yesterday for my phone. It came with a full mounting kit that I discarded after the ten minutes that took me to place the cover. The same kit could have been used to mount at least a hundred covers. The small slice of civilization I'm part of is extremely wasteful! But, let's analyze that waste. First, energy went into collecting and transporting those materials, plus collateral environmental degradation. Now, energy will be spent collecting and processing my waste, and if it can't be recycled, it will end up also provoking collateral damage. But, if we had infinite cheap energy, recycling all of it would be a no-brainier. Even recycling materials contaminated by radiation would be easy; after all, we already do that to refine fission fuel. Economic incentives? Those are trivial to legislate, absent the environmental cost and with a promise of green-house gases neutrality. Heck, had we infinity cheap energy, we can pack, move out of planet an leave all of Earth as a bio-reserve. In other words, nuclear fusion holds the promise of being such a civilization game-changer, that the question of "is it better than solar in the next ten to thirty years?" is moot. With that said, the next ten to thirty years will be vital to attenuate climate change, so nuclear fusion should not be used as a deterrent for other climate investments we can do today.
sigmoid10 5y ago
>The general idea is that since we have stronger magnets now, we can make a smaller, and therefore cheaper tokamak quickly. It's not that simple. The big problem with magnetic confinement fusion is that you need to control turbulence in the plasma so that you can contain the reactions for a reasonable amount of time to extract useful energy. However, turbulence increases with stronger magnetic field gradients, which is exactly what you get when making a smaller reactor chamber with stronger magnets. This wouldn't be the first project claiming to be able to build a small reactor, only to discover that it's virtually impossible without a major theoretical breakthrough. This is usually left out in the venture capital advertisements for these fusion startups. There's a reason why so much money and effort is spent on ITER - it is the only more or less guaranteed path to fusion with the tech and knowledge we have today.
- lambdatronics 5y ago
  >However, turbulence increases with stronger magnetic field gradients Mmm, this isn't right. The stronger magnetic field reduces turbulence, it's the gradient of the pressure that generates turbulence. As best as anyone can tell, SPARC should be able to get Q~10 without any miracles involved -- the engineering rules of thumb and the advanced simulations all say the same. https://www.cambridge.org/core/journals/journal-of-plasma-physics/article/status-of-the-sparc-physics-basis/B21625B93C0654B955B776566C96DF6B https://www.cambridge.org/core/journals/journal-of-plasma-ph...
  - sigmoid10 5y ago
    >The stronger magnetic field reduces turbulence That's why I specifically said field gradients - i.e. the thing that gets larger when you have a stronger field in a smaller volume. >it's the gradient of the pressure that generates turbulence How exactly do you think that pressure is created? Also, that link you provided is an editorial from one of the directors behind SPARC. If you want an objective analysis that is not geered towards possible investors, you need to look elsewhere. FYI, anyone selling you Q~10 designs without a considerable theoretical breakthrough is almost certainly conning you. If you don't believe me just look at how Lockheed's compact fusion reactor panned out. Stronger magnets are not some kind of miracle solution that will enable fusion tomorrow.
bell-cot 5y ago
Not an expert, but... "Net gain" seems to be the "give us enough $Billions and years and we'll find it" holy grail of fusion power. Vs. a $4 Casio calculator I can buy on Amazon today includes a zero-maintenance solar cell that is good for "net gain, plus useful work". Large-scale solar and wind power are already real-world at commercial scale, with costs per MW-h that pretty much beat every alternative. ( https://en.wikipedia.org/wiki/Cost_of_electricity_by_source https://en.wikipedia.org/wiki/Cost_of_electricity_by_source ) Old-type nuclear (fission) energy has a horrible "what was promised, vs. what was delivered" record. Maybe your equations and power laws are right, and a "big enough" tokamak would be a competitive source of power. But then there are the details, like "big enough will cost $25 Trillion". Followed by delays, cost overruns, etc. I'm thinking that a rational, non-expert taxpayer would say, "This fusion thing is a hundred times worse than NASA's Senate Launch System. Stop wasting my money on it NOW, and let gullible investors waste theirs instead."

by dfdx 5y ago

zetalyrae 5y ago

I've always wondered: why exactly is ITER so expensive, and slow? Is the engineering required at such a standard that it should takes decades of planning and construction and tens of billions of dollars? The timeline is so dilated (started in 1988, first plasma planned for 2025!) it feels like the kind of project that's expected to be cancelled from the start. It just doesn't strike me as obvious that reducing the major radius by a few meters would have such a huge impact on cost/timelines.

LeegleechN 5y ago
It's just an absolutely giant construction project. The mass and volume of the construction goes as the cube of the major radius of the reactor. Back of the envelope, SPARC is (6/1.5)^3 = 64 times smaller than ITER. The construction budget for SPARC is ~$500M, so ITER being tens of billions is in line.
- bigyikes 5y ago
  How do projects like LIGO ever get completed? I’m probably totally naive here, but I thought LIGO is physically larger and has many difficult constraints. The LHC comes to mind as well, and that absolutely dwarfs ITER in physical size. What’s the difference? Dealing with heat output? Superconductors are really hard maybe?
  - sbierwagen 5y ago
    LIGO did take decades to construct, like the LHC. According to LIGO's wikipedia article, it was the most expensive project ever funded by the NSF in 1994.
    - neltnerb 5y ago
      LIGO's size is also deceptive, the legs are kilometers long but the design is an L with the important bit being to vibrationally isolate things, maintain dimensional stability, and maintain vacuum. ITER is likely bigger in terms of volume of concrete or actual footprint.
      - lambdatronics 5y ago
        Hmm, looks like ITER and LHC both use about the same amount of superconductor: around 500 tons. [0]https://ieeexplore.ieee.org/document/1018583 https://ieeexplore.ieee.org/document/1018583 [1]https://www.iter.org/mach/Magnets https://www.iter.org/mach/Magnets
jvanderbot 5y ago

causality0 5y ago

Are those calculations of net gain referring to the total energy generated, or the amount we can realistically capture and put to use?

ncmncm 5y ago
The amount of this we can realistically put to use is, always and forever, exactly zero. The only useful outcome of any of this work is a generation of plasma-fluid physicists with practical experience. Pray we can find them something useful to do when the whole enterprise finally collapses.
- liamwire 5y ago
  You keep making these assertions, failing to back them up with anything other than hand-waving in the direction of entirely unrelated programs. You then respond to requests for citations, or even just an elaboration, with the near-verbatim ‘do your own research.’ Chiefly, how does that further the conversation? More pointedly, why should we listen to you? Credentialism in this arena is valid, and what I currently see are multiple subject matter experts, albeit with a bias/incentive towards believing in themselves, versus you. Please substantiate your claims, or word them more carefully as to reflect them being conjecture.
- Kelteseth 5y ago
  Huh, I heard the same (tinfoil) argument about climate change, that all scientist make up the crisis to keep their jobs/funding.
  - ncmncm 5y ago
    Scientists are not the ones making the big bucks on fusion demonstrator construction. But, obviously, somebody is. Are. Every cent of overrun goes into a pocket. None of it evaporates.
lambdatronics 5y ago
You can assume that they're talking about the total generated. They call this the "scientific gain" whereas the "engineering gain" would include all the inefficiencies of the particle beam injectors that put power into the tokamak, and the inefficiency of the steam turbine that makes electrical power from the fusion heat exhaust, and the auxilliary power to run all the pumps, etc. It's generally thought that the "engineering gain" needs to be at least 5, and the "scientific gain" at least 30, for a working reactor. ITER's supposed to hit scientific gain of something like 10-20, which is close.

yboris 5y ago

A march 2019 talk by Dr. Dennis Whyte of MIT working on SPARC https://www.psfc.mit.edu/sparc https://www.psfc.mit.edu/sparc https://www.youtube.com/watch?v=rY6U4wB-oYM https://www.youtube.com/watch?v=rY6U4wB-oYM

mchusma 5y ago

You are right, people who flippantly dismiss fusion just don't understand it. -Fusion has made consistent improvement, roughly in line with expectations for the level of investment (20 years away predictions were considering if we invested massively, which we did not). - Fusion is in theory something that could give us true energy abundance. Want to just desalinate water like crazy? Want to extract gigatons of carbon? Working fusion enables these to happen woth existing technologies. I like to think of solar, batteries, fission, and wind as compelling ways to go mostly carbon free and lower energy costs about 2x over the next 20 years or so. Fusion is what reduces energy cost potentially another 10x, which really changes the game for lots of things. Exciting stuff. Kudos to this team.

pfdietz 5y ago
> Fusion is what reduces energy cost potentially another 10x How did you arrive at that conclusion?
- stjohnswarts 5y ago
  Probably counting in the cost of unlimited global warming and all the damage it will do if we don't stop it, which we won't if current efforts are par for the course.
  - deleted 5y ago
    [deleted]
  - pfdietz 5y ago
    That would make sense if he's comparing only against fossil fuels. But what was written was: > I like to think of solar, batteries, fission, and wind as compelling ways to go mostly carbon free and lower energy costs about 2x over the next 20 years or so. > Fusion is what reduces energy cost potentially another 10x, which really changes the game for lots of things. Exciting stuff. Kudos to this team. If the 10x is from avoiding fossil fuels, why does fusion get that credit, but the other non-fossil sources don't?

ArtWomb 5y ago

Delay in fusion progress seems to mirror HTS design difficulties. A brittle ceramic, in a punishing maelstrom ;) VIPER: an industrially scalable high-current high-temperature superconductor cable https://iopscience.iop.org/article/10.1088/1361-6668/abb8c0 https://iopscience.iop.org/article/10.1088/1361-6668/abb8c0

vmception 5y ago

This is the best synopsis I’ve ever seen about it, but the skepticism comes from the lack of results A whole generation heard about it in school decades ago. Multiple generations by now, even. Its right up there with battery/energy-storage technologies. Headline after headline, enrapturing a newer and newer idealist set of people to quickly become disillusioned. People just get tired of it. But I’m glad to understand whats going on behind the scenes now. I’ll pay attention. Looks like a real sleeper.

tsimionescu 5y ago

There are still fundamental problems with fusion reactors that are unlikely to make them economically viable, or even carbon neutral. Most notably, the extreme temperatures, hydrogen pumping, and high-energy neutron bombardment mean that, even with liquid metal blankets, the reactors will very quickly become brittle, probably not lasting more than a year or two. Since neutron bombardment also turns any material radioactive, not only do you need to tear down your fusion plant (or at least the expensive reactor part of it) every few years, but you have to do it with radiation-resistant robots, as human workers can't get close to the reactor after it's been operating for a while. https://thebulletin.org/fusion-energy-nuclear-fusion/ https://thebulletin.org/fusion-energy-nuclear-fusion/

dsign 5y ago
> Since neutron bombardment also turns any material radioactive, not only do you need to tear down your fusion plant (or at least the expensive reactor part of it) every few years, but you have to do it with radiation-resistant robots, as human workers can't get close to the reactor after it's been operating for a while. I bought a new screen cover yesterday for my phone. It came with a full mounting kit that I discarded after the ten minutes that took me to place the cover. The same kit could have been used to mount at least a hundred covers. The small slice of civilization I'm part of is extremely wasteful! But, let's analyze that waste. First, energy went into collecting and transporting those materials, plus collateral environmental degradation. Now, energy will be spent collecting and processing my waste, and if it can't be recycled, it will end up also provoking collateral damage. But, if we had infinite cheap energy, recycling all of it would be a no-brainier. Even recycling materials contaminated by radiation would be easy; after all, we already do that to refine fission fuel. Economic incentives? Those are trivial to legislate, absent the environmental cost and with a promise of green-house gases neutrality. Heck, had we infinity cheap energy, we can pack, move out of planet an leave all of Earth as a bio-reserve. In other words, nuclear fusion holds the promise of being such a civilization game-changer, that the question of "is it better than solar in the next ten to thirty years?" is moot. With that said, the next ten to thirty years will be vital to attenuate climate change, so nuclear fusion should not be used as a deterrent for other climate investments we can do today.

sigmoid10 5y ago

>The general idea is that since we have stronger magnets now, we can make a smaller, and therefore cheaper tokamak quickly. It's not that simple. The big problem with magnetic confinement fusion is that you need to control turbulence in the plasma so that you can contain the reactions for a reasonable amount of time to extract useful energy. However, turbulence increases with stronger magnetic field gradients, which is exactly what you get when making a smaller reactor chamber with stronger magnets. This wouldn't be the first project claiming to be able to build a small reactor, only to discover that it's virtually impossible without a major theoretical breakthrough. This is usually left out in the venture capital advertisements for these fusion startups. There's a reason why so much money and effort is spent on ITER - it is the only more or less guaranteed path to fusion with the tech and knowledge we have today.

lambdatronics 5y ago
>However, turbulence increases with stronger magnetic field gradients Mmm, this isn't right. The stronger magnetic field reduces turbulence, it's the gradient of the pressure that generates turbulence. As best as anyone can tell, SPARC should be able to get Q~10 without any miracles involved -- the engineering rules of thumb and the advanced simulations all say the same. https://www.cambridge.org/core/journals/journal-of-plasma-physics/article/status-of-the-sparc-physics-basis/B21625B93C0654B955B776566C96DF6B https://www.cambridge.org/core/journals/journal-of-plasma-ph...
- sigmoid10 5y ago
  >The stronger magnetic field reduces turbulence That's why I specifically said field gradients - i.e. the thing that gets larger when you have a stronger field in a smaller volume. >it's the gradient of the pressure that generates turbulence How exactly do you think that pressure is created? Also, that link you provided is an editorial from one of the directors behind SPARC. If you want an objective analysis that is not geered towards possible investors, you need to look elsewhere. FYI, anyone selling you Q~10 designs without a considerable theoretical breakthrough is almost certainly conning you. If you don't believe me just look at how Lockheed's compact fusion reactor panned out. Stronger magnets are not some kind of miracle solution that will enable fusion tomorrow.

bell-cot 5y ago

Not an expert, but... "Net gain" seems to be the "give us enough $Billions and years and we'll find it" holy grail of fusion power. Vs. a $4 Casio calculator I can buy on Amazon today includes a zero-maintenance solar cell that is good for "net gain, plus useful work". Large-scale solar and wind power are already real-world at commercial scale, with costs per MW-h that pretty much beat every alternative. ( https://en.wikipedia.org/wiki/Cost_of_electricity_by_source https://en.wikipedia.org/wiki/Cost_of_electricity_by_source ) Old-type nuclear (fission) energy has a horrible "what was promised, vs. what was delivered" record. Maybe your equations and power laws are right, and a "big enough" tokamak would be a competitive source of power. But then there are the details, like "big enough will cost $25 Trillion". Followed by delays, cost overruns, etc. I'm thinking that a rational, non-expert taxpayer would say, "This fusion thing is a hundred times worse than NASA's Senate Launch System. Stop wasting my money on it NOW, and let gullible investors waste theirs instead."