7 ms·

It's still decades off but as I understand it, this was the hardest nut to crack. They got what, 2.5 megajoules out of 2.1 in? I might be in the opposite camp

It's still decades off but as I understand it, this was the hardest nut to crack. They got what, 2.5 megajoules out of 2.1 in? I might be in the opposite camp as you but this is very much a "where were you when—" moment for me. I'm sure someone will pop in to disappoint me but I think the point is it's no longer a hypothetical exercise.

acidburnNSA 4y ago
> They got what, 2.5 megajoules out of 2.1 in? Of laser energy into a tiny control volume that doesn't consider how much energy went into the laser systems. If you draw the control volume around the building and see that the lasers require vastly more energy than what came out, I think you'll be less excited, right? We've been getting lots of energy out of fusion since the early 1950s with thermonuclear bombs. We know we can get energy out of a control volume. But is it a practical energy source is still the question imho.
- PietdeVries 4y ago
  I think fusion-plants have always been "15 years away", and most likely will be so for quite a few years... Edit: I was wrong, fusion is always 30 years away: https://www.discovermagazine.com/technology/why-nuclear-fusion-is-always-30-years-away https://www.discovermagazine.com/technology/why-nuclear-fusi...
  - soperj 4y ago
    I don't know what people get out of repeating this on every single fusion article. It's not inventive or insightful, and it doesn't further the discussion in the slightest.
    - dylan604 4y ago
      Because it's A) true, B) relevant to keep all of the hype in check. The year of Linux on the desktop is always right around the corner too. Yes, they are tropes, but they were not born out of nothing. Someone has to keep the bloviated PR campaigns checked with reality. Otherwise, some crazy fools might actually start believing that fusion is real and gets duped out of their money. If you can't stand a bit of real criticism, then maybe you should sell your scam somewhere else. Otherwise, take it on the chin, retool your message, and come at it honestly.
      - Veen 4y ago
        It's not a trope; it's a cliché. There's nothing wrong with poking holes in overinflated hype, but do they have to be so boring and repetitive about it.
        dylan604 4y ago
        If you keep telling me the same thing with the same lack of results, I could say the same to you as being boring and repetitive. Just because you say 2+2=5 and someone tells you you're wrong every time doesn't mean they are boring and repetitive.
        kelnos 4y ago
        How is this "lack of results"? This particular announcement is a huge result! Maybe it's not the result you think it should be ("with all they hype over decades, we should have fusion power by now"), but... too bad. It is what it is, and this particular announcement is indeed impressive.
        moloch-hai 4y ago
        It is not, in fact, a huge result, except insofar as it is convenient for further weapons research. It does not bring civil fusion power even a single day nearer.
        godelski 4y ago
        It's also just a parrot trick. There's no reason behind why it is 30 years away or even why 30 instead of 15 instead of 20. It is just a line. These numbers are meaningless but touted as a way to add validity to the argument without providing actual evidence for why fusion is such a tough nut to crack. We should dispose of hype, but let's do it from a place of understanding. I hope we're a bit smarter than parrots.
      - soperj 4y ago
        It's not true. The original quote was 30 years given current funding. They reduced the funding and surprise surprise it didn't get done. It's like when you estimate how long a project will take given a thousand people, and they reduce the number of people on the project to one person and then hold you to the original estimate.
    - abfan1127 4y ago
      some people are new to the Fusion discussion. They've missed the last 50 yrs of "fusion is 10 yrs away" claims. Over the years, I've learned to temper all discovery excitement. Its the other side of the coin equivalent of the the XKCD 10000 comic[1]. [1] https://xkcd.com/1053/ https://xkcd.com/1053/
    - TrevorJ 4y ago
      Because it is context that is rarely included in the article.
- sharikous 4y ago
  Could you elaborate on that? What do you mean that the lasers could require more energy? Is it that in a specific volume they got X EM energy coming in from the laser and Y thermal energy coming out, with Y>X BUT the electricity consumption of the lasers is Z>Y>X? If so that's sort of misleading, like the plethora of claims from ITER. I hoped this was different.
  - foxyv 4y ago
    So the laser energy that went into the reaction in the form of light is less than what came out of the reaction. However, the energy needed to produce that laser energy may be orders of magnitude more depending on the laser. AKA: the Wall Plug Efficiency. Tabletop rigs can be as efficient as 50%, however high power such as we see here tends to come with drastically reduced efficiency.
  - ansible 4y ago
    Not /u/acidburnNSA, but what was meant is that no laser is 100% efficient. Not only do they not convert 100% of their electrical input into laser energy, but they also require other support systems, notably cooling. So we need to consider the total energy costs of the building the fusion experiment is conducted in, not just the physically small area where the fusion reaction is happening inside the reactor. Still, this is an important step in the development of fusion energy reactors.
  - derefr 4y ago
    Presumably they mean that there are efficiency losses in charging the supercapacitor banks used to fire the lasers; so that if you consider the system over multiple duty cycles rather than over a single cycle, it's no longer energy-positive. (I.e. if the system were capturing its emitted energy — and that emitted energy needed to be enough to act as a grid power source feeding input power to the supercapacitors, rather than merely being the equivalent of the direct output power of the lasers per shot — then it wouldn't be enough to sustain the reaction.) But personally, I don't know whether that's actually important. Power plants usually consume a nontrivial fraction of their own produced power to power themselves, and in fact consume more than 100% of produced power when starting from a full stop — meaning that in initial few-shot conditions, even when feeding back their own produced power into themselves, they still need (huge amounts of) external power input to get going, like a car engine needing a battery + starter motor. Only a rare few kinds of power plant can be used to "black start" a power grid. Most types of generator need to overcome initial higher resistances, e.g. inertia (and thereby back-EMF resistance at the transformer) in getting heavy turbines spinning from a stop. It wouldn't be at all strange if a practical fusion power plant turned out to be energy-negative over a few-shot run (i.e. required "bootstrapping"), but then became energy positive over a theoretical 24/7 run at whatever its optimal duty cycle is. And a single-shot run becoming net-positive would be a good point to start to consider those more practical calculations, since they'd have been useless to consider until then—a power plant can't possibly be net-positive over any kind of runtime + duty cycle, if its core reaction can't be net-energy-positive when considered in isolation. Which is, to me, why it probably does make sense for ITER to be excited. They've reached the point where they can stop using a lab-bench model of power efficiency, and start trying to come up with another, more full-scale model of power efficiency to replace it with.
reacharavindh 4y ago
Not an engineer in this field, so I may have misread/misunderstood, but I read that 2.5MJ out for 2.1MJ of laser energy in, NOT the total energy needed to make the whole thing work.. So, in a layman’s world, it is not a net gain of power, only a small subset of the system yielding more power than it took in. Happy to be proven wrong and told that it is more of a breakthrough than I think it is..
- VaxWithSex 4y ago
  No, you are correct.
  - galangalalgol 4y ago
    So they are ignoring the laser efficiency as well as the thermal to electric efficiency? If you did the same for a tokamak, stellerator or Bussard, would you get a similar ratio?
    - VaxWithSex 4y ago
      Jup. Fusion research is necessary and funding should be provided. But it is not close to commercial or generative viability. So there is at the moment no working design for a generator as a plant that produces more electricity than it takes in.
      - whimsicalism 4y ago
        Yup? Absolutely not, nothing close to this has been achieved with other reactors.
VaxWithSex 4y ago
The net energy gain is very slim and has to be converted to electricity to power the lasers – in doing so, there's so much loss, it is again NEGATIVE. It's always the same…
- Robotbeat 4y ago
  As it always is with new, unproven things.
  - VaxWithSex 4y ago
    or fusion. There are always these articles: net energy gain finally! and then: no not really.
    - Robotbeat 4y ago
      Reminds me of solar. That took a century to get to where we are today where the net energy output is much greater than the energy needed to manufacture them. It being hard and it requiring continual progress does not mean that progress does not occur.
      - VaxWithSex 4y ago
        Correct. Nuclear fusion research should be funded and realistic goals be set.
        Robotbeat 4y ago
        …which is exactly what this is?
      - hotpotamus 4y ago
        How long has humanity been working on fusion? Wasn't Ivy Mike in the early 50's? Glaciers continually progress too, but it's not obvious on human timescales.
Someone 4y ago
Electricity in, heat out, I think. Getting that heat back to electricity will cost some, I expect more than that 0.4
- fanf2 4y ago
  The efficiency of a thermal power plant is around 40%, depending on the temperature of the steam it can produce. https://en.wikipedia.org/wiki/Thermal_power_station#Thermal_power_generation_efficiency https://en.wikipedia.org/wiki/Thermal_power_station#Thermal_...
  - mayama 4y ago
    Note that energy in the case of ICF is produced instantaneously. There is no approach to capture this energy in production at this moment. Capturing that enery is still ongoing research topic.

acidburnNSA 4y ago

> They got what, 2.5 megajoules out of 2.1 in? Of laser energy into a tiny control volume that doesn't consider how much energy went into the laser systems. If you draw the control volume around the building and see that the lasers require vastly more energy than what came out, I think you'll be less excited, right? We've been getting lots of energy out of fusion since the early 1950s with thermonuclear bombs. We know we can get energy out of a control volume. But is it a practical energy source is still the question imho.

PietdeVries 4y ago
I think fusion-plants have always been "15 years away", and most likely will be so for quite a few years... Edit: I was wrong, fusion is always 30 years away: https://www.discovermagazine.com/technology/why-nuclear-fusion-is-always-30-years-away https://www.discovermagazine.com/technology/why-nuclear-fusi...
- soperj 4y ago
  I don't know what people get out of repeating this on every single fusion article. It's not inventive or insightful, and it doesn't further the discussion in the slightest.
  - dylan604 4y ago
    Because it's A) true, B) relevant to keep all of the hype in check. The year of Linux on the desktop is always right around the corner too. Yes, they are tropes, but they were not born out of nothing. Someone has to keep the bloviated PR campaigns checked with reality. Otherwise, some crazy fools might actually start believing that fusion is real and gets duped out of their money. If you can't stand a bit of real criticism, then maybe you should sell your scam somewhere else. Otherwise, take it on the chin, retool your message, and come at it honestly.
    - Veen 4y ago
      It's not a trope; it's a cliché. There's nothing wrong with poking holes in overinflated hype, but do they have to be so boring and repetitive about it.
      - dylan604 4y ago
        If you keep telling me the same thing with the same lack of results, I could say the same to you as being boring and repetitive. Just because you say 2+2=5 and someone tells you you're wrong every time doesn't mean they are boring and repetitive.
        kelnos 4y ago
        How is this "lack of results"? This particular announcement is a huge result! Maybe it's not the result you think it should be ("with all they hype over decades, we should have fusion power by now"), but... too bad. It is what it is, and this particular announcement is indeed impressive.
        moloch-hai 4y ago
        It is not, in fact, a huge result, except insofar as it is convenient for further weapons research. It does not bring civil fusion power even a single day nearer.
      - godelski 4y ago
        It's also just a parrot trick. There's no reason behind why it is 30 years away or even why 30 instead of 15 instead of 20. It is just a line. These numbers are meaningless but touted as a way to add validity to the argument without providing actual evidence for why fusion is such a tough nut to crack. We should dispose of hype, but let's do it from a place of understanding. I hope we're a bit smarter than parrots.
    - soperj 4y ago
      It's not true. The original quote was 30 years given current funding. They reduced the funding and surprise surprise it didn't get done. It's like when you estimate how long a project will take given a thousand people, and they reduce the number of people on the project to one person and then hold you to the original estimate.
  - abfan1127 4y ago
    some people are new to the Fusion discussion. They've missed the last 50 yrs of "fusion is 10 yrs away" claims. Over the years, I've learned to temper all discovery excitement. Its the other side of the coin equivalent of the the XKCD 10000 comic[1]. [1] https://xkcd.com/1053/ https://xkcd.com/1053/
  - TrevorJ 4y ago
    Because it is context that is rarely included in the article.
sharikous 4y ago
Could you elaborate on that? What do you mean that the lasers could require more energy? Is it that in a specific volume they got X EM energy coming in from the laser and Y thermal energy coming out, with Y>X BUT the electricity consumption of the lasers is Z>Y>X? If so that's sort of misleading, like the plethora of claims from ITER. I hoped this was different.
- foxyv 4y ago
  So the laser energy that went into the reaction in the form of light is less than what came out of the reaction. However, the energy needed to produce that laser energy may be orders of magnitude more depending on the laser. AKA: the Wall Plug Efficiency. Tabletop rigs can be as efficient as 50%, however high power such as we see here tends to come with drastically reduced efficiency.
- ansible 4y ago
  Not /u/acidburnNSA, but what was meant is that no laser is 100% efficient. Not only do they not convert 100% of their electrical input into laser energy, but they also require other support systems, notably cooling. So we need to consider the total energy costs of the building the fusion experiment is conducted in, not just the physically small area where the fusion reaction is happening inside the reactor. Still, this is an important step in the development of fusion energy reactors.
- derefr 4y ago
  Presumably they mean that there are efficiency losses in charging the supercapacitor banks used to fire the lasers; so that if you consider the system over multiple duty cycles rather than over a single cycle, it's no longer energy-positive. (I.e. if the system were capturing its emitted energy — and that emitted energy needed to be enough to act as a grid power source feeding input power to the supercapacitors, rather than merely being the equivalent of the direct output power of the lasers per shot — then it wouldn't be enough to sustain the reaction.) But personally, I don't know whether that's actually important. Power plants usually consume a nontrivial fraction of their own produced power to power themselves, and in fact consume more than 100% of produced power when starting from a full stop — meaning that in initial few-shot conditions, even when feeding back their own produced power into themselves, they still need (huge amounts of) external power input to get going, like a car engine needing a battery + starter motor. Only a rare few kinds of power plant can be used to "black start" a power grid. Most types of generator need to overcome initial higher resistances, e.g. inertia (and thereby back-EMF resistance at the transformer) in getting heavy turbines spinning from a stop. It wouldn't be at all strange if a practical fusion power plant turned out to be energy-negative over a few-shot run (i.e. required "bootstrapping"), but then became energy positive over a theoretical 24/7 run at whatever its optimal duty cycle is. And a single-shot run becoming net-positive would be a good point to start to consider those more practical calculations, since they'd have been useless to consider until then—a power plant can't possibly be net-positive over any kind of runtime + duty cycle, if its core reaction can't be net-energy-positive when considered in isolation. Which is, to me, why it probably does make sense for ITER to be excited. They've reached the point where they can stop using a lab-bench model of power efficiency, and start trying to come up with another, more full-scale model of power efficiency to replace it with.

reacharavindh 4y ago

Not an engineer in this field, so I may have misread/misunderstood, but I read that 2.5MJ out for 2.1MJ of laser energy in, NOT the total energy needed to make the whole thing work.. So, in a layman’s world, it is not a net gain of power, only a small subset of the system yielding more power than it took in. Happy to be proven wrong and told that it is more of a breakthrough than I think it is..

VaxWithSex 4y ago
No, you are correct.
- galangalalgol 4y ago
  So they are ignoring the laser efficiency as well as the thermal to electric efficiency? If you did the same for a tokamak, stellerator or Bussard, would you get a similar ratio?
  - VaxWithSex 4y ago
    Jup. Fusion research is necessary and funding should be provided. But it is not close to commercial or generative viability. So there is at the moment no working design for a generator as a plant that produces more electricity than it takes in.
    - whimsicalism 4y ago
      Yup? Absolutely not, nothing close to this has been achieved with other reactors.

VaxWithSex 4y ago

The net energy gain is very slim and has to be converted to electricity to power the lasers – in doing so, there's so much loss, it is again NEGATIVE. It's always the same…

Robotbeat 4y ago
As it always is with new, unproven things.
- VaxWithSex 4y ago
  or fusion. There are always these articles: net energy gain finally! and then: no not really.
  - Robotbeat 4y ago
    Reminds me of solar. That took a century to get to where we are today where the net energy output is much greater than the energy needed to manufacture them. It being hard and it requiring continual progress does not mean that progress does not occur.
    - VaxWithSex 4y ago
      Correct. Nuclear fusion research should be funded and realistic goals be set.
      - Robotbeat 4y ago
        …which is exactly what this is?
    - hotpotamus 4y ago
      How long has humanity been working on fusion? Wasn't Ivy Mike in the early 50's? Glaciers continually progress too, but it's not obvious on human timescales.

Someone 4y ago

Electricity in, heat out, I think. Getting that heat back to electricity will cost some, I expect more than that 0.4

fanf2 4y ago
The efficiency of a thermal power plant is around 40%, depending on the temperature of the steam it can produce. https://en.wikipedia.org/wiki/Thermal_power_station#Thermal_power_generation_efficiency https://en.wikipedia.org/wiki/Thermal_power_station#Thermal_...
- mayama 4y ago
  Note that energy in the case of ICF is produced instantaneously. There is no approach to capture this energy in production at this moment. Capturing that enery is still ongoing research topic.