10 ms·

Fusion Turns Up the Heat

36 points by swamp40 4y ago

Footkerchief 4y ago
Reminder that NIF is research for weapons, not power generation.
- beeboop 4y ago
  From their website: > [We] conduct one-of-a-kind experiments that help ensure the nation’s security through stockpile stewardship, make important advances toward achieving fusion ignition in the laboratory for the first time, and lay the groundwork for a safe, carbon-free, secure energy future through inertial fusion energy. It seems their main thing is safe maintenance/storage of nuclear stockpiles, but it's not their only thing
  - pfdietz 4y ago
    When energy people express skepticism about the value of NIF, the NIF team says it's for weapons work. When weapons people express skepticism about the value of NIF, the NIF team says it's for energy work.
    - throwoutway 4y ago
      Maybe they have dual missions? That’s not unusual in government agencies For example when a military Is standing around they tend to do peaceful things like help deliver emergency supplies to areas hit by natural disasters. Militaries have great logistics and are used to going to “hard to reach” locations. And after the Cold War, nuclear subs support whale researchers by monitoring them
      - pfdietz 4y ago
        The point is that unless the weapons and energy people team up and compare their criticisms, each can be deflected by reference to the other.
  - ncmncm 4y ago
    The word "safe" has a very specific, legal meaning as applied by the US DoE. It means, informally, "it goes bang when you push the button". Period. It does not, in particular, mean "it doesn't go bang when you don't push the button". Nor, "it doesn't leak radioactives into ground water", nor "it doesn't land in terrorists' hands", or "doesn't fall into farmers' fields and blow up", or literally anything else. Similarly, DoE's one other statutory responsibility, "reliability", means "it makes as big a bang as designed for", and literally nothing else. Every other thing you can think of is literally somebody else's job, if indeed anybody's.
im3w1l 4y ago
> Fulfilling the Lawson criterion for a burning plasma doesn’t yet mean that we can produce useful energy with fusion power plants. The next step toward that goal would be to demonstrate a fusion scheme that produces as much energy as that contained in the laser pulses driving the reaction. In other words, the scheme should have a net gain, G, of 1. This is what I had always kinda sorta thought, but seeing someone put it in words made me realize that it actually doesn't make sense at all. If 1 unit of laser energy gets you 0.2 units of fusion, that means you end up with 1.2 units of heat energy total. Okay so 1.2 units of heat just sounds like a crappy heat pump. But given that the heat is so damn hot (meaning ~0 entropy) you could in theory convert it all to electricity and come out ahead.
- sacred_numbers 4y ago
  The main problem is that -- especially with laser fusion-- you are not inputting 1 unit of electricity and getting out 1.2 units of high grade heat. You are inputting 100 units of electricity, most of which is lost as low grade heat through wires, cooling devices, etc to power a laser that outputs 1 unit of photons. The fusion adds a bit of energy, but not enough to surpass the 100 units you put in. I don't know the exact efficiency of these lasers, so 100x may be wrong, but I think I'm in the right order of magnitude.
  - im3w1l 4y ago
    Ah that makes sense. I had no idea the lasers were that inefficient. Still it's not an inherent feature of the problem. But maybe getting the fusion reaction to self-sustain is the easier thing to solve.
    - nine_k 4y ago
      Lasers are likely 10% efficient, not 1%, but it's still an order of magnitude less than needed to break even.
      - fsh 4y ago
        The laser at NIF has a 0.5% efficiency [1]. Some lasers are highly efficient (for example diode lasers). High-energy pulsed lasers are usually not. [1] https://physics.aps.org/articles/v14/168 https://physics.aps.org/articles/v14/168
onlyrealcuzzo 4y ago
> The current results are thus tantalizingly close to achieving unit gain—at the current rate of improvement, I expect this to happen within the next couple of years. Does anyone have a graph of the rate of improvement? I'm curious. > But for a fusion reactor to be commercially viable and deliver a sizeable amount of electricity to the grid, much higher gains (of order 100) are needed to compensate for the wall-plug efficiency of the laser and for the losses in energy collection and in the electricity production and distribution system. Can anyone ELI8 why it needs to be 100? That seems excessive. IIUC, almost all the heat (at Fusion temps) can be turned to electricity. IIUC only about 5% of energy is lost during transfer. Is ~90% of power really being lost somewhere else? And if so, where!? This seems like a problem more easily solved than Fusion... In my naive mind - G of even 2 seems like literally a money printing machine... I get it - a ridiculously expensive money printing machine to build. Does it print dollars fast enough to pay for building it, and maintaining it, etc... Also, I know Newsweek isn't a great source, but they have another article about this experiment at the NIF: https://www.newsweek.com/nuclear-fusion-energy-milestone-ignition-confirmed-california-1733238?amp=1 https://www.newsweek.com/nuclear-fusion-energy-milestone-ign...
- deleted 4y ago
  [deleted]
- sigmoid10 4y ago
  >Does anyone have a graph of the rate of improvement? It's not exactly a timeline, but you can roughly see the Lawson criteria development over the decades in figure 4 from this paper: https://link.springer.com/article/10.1007/s13280-015-0732-y https://link.springer.com/article/10.1007/s13280-015-0732-y >In my naive mind - G of even 2 seems like literally a money printing machine... That will get you nothing when you consider that a steam turbine has a maximal efficiency below 50% - and that's already pretty much the best way we have of turning heat into electricity. In practice there are also tons of other losses, so a G of at least 10 is probably required to get just about anything economical from it, and only a G of 100 or more would be a real money printing machine.
  - ncmncm 4y ago
jonathaneunice 4y ago
> Without doubt, fusion reactors are going from strength to strength A cheeky way to say "from nowhere near where they need to be to not quite there," fusion fanbois!
- 77pt77 4y ago
  20 years away, just like 20 years ago...
  - adrianN 4y ago
    Can we stop posting this same comment under every article mentioning fusion? Inevitably someone then answers with the graph that shows funding over time and a whole chain of comments repeats for each of these articles.
    - ncmncm 4y ago
      Yes, it promotes the fiction that there will ever be commercially competitive fusion. The more we learn, the farther into the future the prospect recedes.

36 points by swamp40 4y ago

Footkerchief 4y ago

Reminder that NIF is research for weapons, not power generation.

beeboop 4y ago
From their website: > [We] conduct one-of-a-kind experiments that help ensure the nation’s security through stockpile stewardship, make important advances toward achieving fusion ignition in the laboratory for the first time, and lay the groundwork for a safe, carbon-free, secure energy future through inertial fusion energy. It seems their main thing is safe maintenance/storage of nuclear stockpiles, but it's not their only thing
- pfdietz 4y ago
  When energy people express skepticism about the value of NIF, the NIF team says it's for weapons work. When weapons people express skepticism about the value of NIF, the NIF team says it's for energy work.
  - throwoutway 4y ago
    Maybe they have dual missions? That’s not unusual in government agencies For example when a military Is standing around they tend to do peaceful things like help deliver emergency supplies to areas hit by natural disasters. Militaries have great logistics and are used to going to “hard to reach” locations. And after the Cold War, nuclear subs support whale researchers by monitoring them
    - pfdietz 4y ago
      The point is that unless the weapons and energy people team up and compare their criticisms, each can be deflected by reference to the other.
- ncmncm 4y ago
  The word "safe" has a very specific, legal meaning as applied by the US DoE. It means, informally, "it goes bang when you push the button". Period. It does not, in particular, mean "it doesn't go bang when you don't push the button". Nor, "it doesn't leak radioactives into ground water", nor "it doesn't land in terrorists' hands", or "doesn't fall into farmers' fields and blow up", or literally anything else. Similarly, DoE's one other statutory responsibility, "reliability", means "it makes as big a bang as designed for", and literally nothing else. Every other thing you can think of is literally somebody else's job, if indeed anybody's.

im3w1l 4y ago

> Fulfilling the Lawson criterion for a burning plasma doesn’t yet mean that we can produce useful energy with fusion power plants. The next step toward that goal would be to demonstrate a fusion scheme that produces as much energy as that contained in the laser pulses driving the reaction. In other words, the scheme should have a net gain, G, of 1. This is what I had always kinda sorta thought, but seeing someone put it in words made me realize that it actually doesn't make sense at all. If 1 unit of laser energy gets you 0.2 units of fusion, that means you end up with 1.2 units of heat energy total. Okay so 1.2 units of heat just sounds like a crappy heat pump. But given that the heat is so damn hot (meaning ~0 entropy) you could in theory convert it all to electricity and come out ahead.

sacred_numbers 4y ago
The main problem is that -- especially with laser fusion-- you are not inputting 1 unit of electricity and getting out 1.2 units of high grade heat. You are inputting 100 units of electricity, most of which is lost as low grade heat through wires, cooling devices, etc to power a laser that outputs 1 unit of photons. The fusion adds a bit of energy, but not enough to surpass the 100 units you put in. I don't know the exact efficiency of these lasers, so 100x may be wrong, but I think I'm in the right order of magnitude.
- im3w1l 4y ago
  Ah that makes sense. I had no idea the lasers were that inefficient. Still it's not an inherent feature of the problem. But maybe getting the fusion reaction to self-sustain is the easier thing to solve.
  - nine_k 4y ago
    Lasers are likely 10% efficient, not 1%, but it's still an order of magnitude less than needed to break even.
    - fsh 4y ago
      The laser at NIF has a 0.5% efficiency [1]. Some lasers are highly efficient (for example diode lasers). High-energy pulsed lasers are usually not. [1] https://physics.aps.org/articles/v14/168 https://physics.aps.org/articles/v14/168

onlyrealcuzzo 4y ago

> The current results are thus tantalizingly close to achieving unit gain—at the current rate of improvement, I expect this to happen within the next couple of years. Does anyone have a graph of the rate of improvement? I'm curious. > But for a fusion reactor to be commercially viable and deliver a sizeable amount of electricity to the grid, much higher gains (of order 100) are needed to compensate for the wall-plug efficiency of the laser and for the losses in energy collection and in the electricity production and distribution system. Can anyone ELI8 why it needs to be 100? That seems excessive. IIUC, almost all the heat (at Fusion temps) can be turned to electricity. IIUC only about 5% of energy is lost during transfer. Is ~90% of power really being lost somewhere else? And if so, where!? This seems like a problem more easily solved than Fusion... In my naive mind - G of even 2 seems like literally a money printing machine... I get it - a ridiculously expensive money printing machine to build. Does it print dollars fast enough to pay for building it, and maintaining it, etc... Also, I know Newsweek isn't a great source, but they have another article about this experiment at the NIF: https://www.newsweek.com/nuclear-fusion-energy-milestone-ignition-confirmed-california-1733238?amp=1 https://www.newsweek.com/nuclear-fusion-energy-milestone-ign...

deleted 4y ago
[deleted]
sigmoid10 4y ago
>Does anyone have a graph of the rate of improvement? It's not exactly a timeline, but you can roughly see the Lawson criteria development over the decades in figure 4 from this paper: https://link.springer.com/article/10.1007/s13280-015-0732-y https://link.springer.com/article/10.1007/s13280-015-0732-y >In my naive mind - G of even 2 seems like literally a money printing machine... That will get you nothing when you consider that a steam turbine has a maximal efficiency below 50% - and that's already pretty much the best way we have of turning heat into electricity. In practice there are also tons of other losses, so a G of at least 10 is probably required to get just about anything economical from it, and only a G of 100 or more would be a real money printing machine.
- ncmncm 4y ago

jonathaneunice 4y ago

> Without doubt, fusion reactors are going from strength to strength A cheeky way to say "from nowhere near where they need to be to not quite there," fusion fanbois!

77pt77 4y ago
20 years away, just like 20 years ago...
- adrianN 4y ago
  Can we stop posting this same comment under every article mentioning fusion? Inevitably someone then answers with the graph that shows funding over time and a whole chain of comments repeats for each of these articles.
  - ncmncm 4y ago
    Yes, it promotes the fiction that there will ever be commercially competitive fusion. The more we learn, the farther into the future the prospect recedes.