7 ms·

I have yet to read an article or paper which has convinced me that energy generating fusion is possible at low costs and with materials that we currently know o

I have yet to read an article or paper which has convinced me that energy generating fusion is possible at low costs and with materials that we currently know of. I don't see why anyone (including governments) should invest in these types of projects. Not only is the science extremely complex, the implementation is a huge engineering challenge. We already have a huge fusion power plant at the heart of our solar system and we can harness its power with some pretty cheap solar panels. If you want to read a better article explaining the science then try http://fusionandthings.eu/2019/06/05/new-calculations-show-proton-boron-fusion-is-still-difficult/ http://fusionandthings.eu/2019/06/05/new-calculations-show-p...

PopePompus 6y ago
Sadly, that huge fusion plant is offline half the time for any given location on the Earth, and is severely degraded by cloudy weather. Also using it to power the world will require large areas of land to be dedicated to collecting its output.
- LargoLasskhyfv 6y ago
  So what? I give you Space Grid ©. [1] https://en.wikipedia.org/wiki/Space-based_solar_power https://en.wikipedia.org/wiki/Space-based_solar_power edit: I don't know why that symbol doesn't show as copyleft as intended.
  - bufbupa 6y ago
    That seems like it could have more difficult engineering problems than a fusion reactor! Seems like a quick way to accidentally microwave a desert into a sea of glass. Hope you don't put anything remotely near the power receiver on earth.
    - DennisP 6y ago
      Power density on the ground would be way lower than you're thinking. The leading proposals, like SPS-Alpha, put a gigawatt-scale power station in geostationary orbit. Power is beamed to ground via microwave. The receiver station has to be kilometers wide, which puts the power density low enough so birds wouldn't be harmed; even that amount of focus is only doable by sending a pilot signal from the receiver, so the beam can't trivially be redirected to other targets. Despite its size, the receiver would be inexpensive, since it's mostly wire antennae.
    - rob74 6y ago
      Hey, think positive! If microwaves prove too dangerous, and they finally do manage to build a cable from the orbital power station down to earth, they have a space elevator as well!
  - mrec 6y ago
    Space advocates seem to have been going off the idea of that over the past few years. I'm not sure how much of that is due to a better appreciation of the downsides, and how much is due to the very rapid improvements we've been seeing in ground-based solar. A couple of recent (late 2019) articles from Casey Handmer: https://caseyhandmer.wordpress.com/2019/08/20/space-based-solar-power-is-not-a-thing/ https://caseyhandmer.wordpress.com/2019/08/20/space-based-so... https://caseyhandmer.wordpress.com/2019/09/20/no-really-space-based-solar-power-is-not-a-useful-idea-literature-review-edition/ https://caseyhandmer.wordpress.com/2019/09/20/no-really-spac... It's worth reading the comments too; there are some interesting points there, although I think the game-changing ones rely on new tech and/or well-developed lunar industry.
    - LargoLasskhyfv 6y ago
      Yes. I'm aware of that. But while economically usable fusion remains SciFi so far, space based solar just lacks some bootstrapping. Which seems to be more attainable as time passes. If "we" really wanted this, we could do it now because the technology is there. There is no what if like in any path to fusion. edit: especially considering all the hype about colonizing Mars, or a Moonbase.
    - pfdietz 6y ago
      Space solar is a way to get the most out of expensive PV cells. But PV is no longer expensive. It's cheaper to just overbuild on Earth and transmit energy through time (storage) rather than through space (microwaves).
- barbegal 6y ago
  There are other options for using the sun's energy. We can grow trees to burn, we can optimise windows and window coverings to use solar energy to heat and cool buildings, we can put solar panels in the dessert, or in the ocean, or above roads or in space (but that's not very cost effective). My go to book on energy is this one http://www.withouthotair.com/ http://www.withouthotair.com/ It gives good numbers for all the energy that we could generate from renewables and all the energy we currently use.
- networkimprov 6y ago
  High-altitude solar platforms: http://www.stratosolar.com/blog http://www.stratosolar.com/blog
- adrianhel 6y ago
  There is a lot of land in the world. And definitely have the capacity to build the supply chains. It's just that it's slow and expensive while oil, gas and nuclear is fast and cheap. We need policy changes. Or in a very ideal world, fusion.
  - pfdietz 6y ago
    New solar is much cheaper than new nuclear, per kWh.
    - adrianhel 6y ago
      I did not know that. That's great!
      - pfdietz 6y ago
        It's startling how quickly this happened. Even ten years ago it wasn't true. Many people have not updated their priors yet and still think nuclear is a realistic option. At this point, nuclear is a long shot, which is why I refer to SMRs as HMRs, "Hail Mary Reactors".
regularfry 6y ago
The one that gave me most hope from this point of view was the Polywell design. It made some waves a few years ago then got classified and sputtered out, then this happened: https://en.wikipedia.org/wiki/Polywell#%22Final_nail%22 https://en.wikipedia.org/wiki/Polywell#%22Final_nail%22? I'm entirely with you as far as tokamaks go - they're relying on unobtainium for a significant component - but I think other designs are possible, just under-researched.
- MauranKilom 6y ago
  Are you aware of https://en.wikipedia.org/wiki/Wendelstein_7-X https://en.wikipedia.org/wiki/Wendelstein_7-X? It is well on its way to produce sustained plasma discharges of multiple minutes. The stellarator design has some decisive advantages over Tokamaks.
  - pfdietz 6y ago
    It does not avoid the generic problem of DT fusion reactors, which is lousy power density. The magnets are also famously complex and expensive.
    - MauranKilom 6y ago
      That sounds like engineering and scaling challenges, not inherent limitations... I mean, they clearly have the magnets figured out and so far there doesn't seem to have been a lot in the way of unforeseen roadblocks.
      - pfdietz 6y ago
        That sounds like the dismissive attitude a plasma physicist, for whom mere engineering issues are trivial and of lesser importance. But engineering issues are perfectly capable of ruining the prospects for a technology. Fission, for example, faces nothing BUT engineering issues (where cost is considered a part of engineering.) The equivalent of breakeven and ignition was achieved for fission in 1942. DT fusion faces fundamental engineering obstacles, obstacles that are not solvable by tweaking the confinement scheme. Scaling up makes the main problem, power density, worse, not better (see a later comment by me on this issue.)
nickparker 6y ago
Have you seen General Fusion? They spin a large ball of molten lead using pumps and shoot hot plasma into the vortex that forms in the middle, then strike the walls of the lead chamber with carefully timed steam pistons to make an implosion pressure wave not entirely unlike Fat Man’s design, except reusable and for fusion. The fusion heat and radiation gets absorbed by the lead and they run a heat exchanger on the pump loop for power generation. They also think they can breed fuel with some lithium in the lead. I love their plan aesthetically but I’m not qualified to judge how feasible it is. It’s very satisfyingly physical though.
- ColanR 6y ago
  Do you know if they've achieved fusion yet? I remember reading about them in PopSci way back in the day, and wondered how they were doing.
- teachrdan 6y ago
  Do you end up with a huge ball of radioactive lead at the end of the day? From what little I know of fusion, it seems you still end up with irradiated lead or other shielding. (And yes, I know that coal releases radiation, and that the installation of solar panels and wind turbines is, currently, a dangerous job, etc.)
  - nickparker 6y ago
    Huh, I suppose you do! I had a naive short-circuit in my head that "neutron flux is bad because it destroys your your materials. If your material is molten lead anyway who cares?" I also didn't know lead has such a low neutron absorption cross section. For what it's worth lead with extra neutrons seems a lot less scary than eg uranium fission waste. Stable isotopes 206, 207, and 208 represent 98% by abundance, 208 has the lowest cross section, and 209 has a 3 hour half-life into Bismuth-209 which is nearly stable (2e19 year half-life). So it seems almost all of your neutron captures just make other stable lead isotopes or briefly-terrifying 209 that's totally safe after a couple days. You only get real scary stuff if the trace amounts of undecayed 209 manage a second capture. Edit: I should add they want to mix lithium into the lead to absorb neutrons and regenerate fuel
m463 6y ago
> I don't see why anyone (including governments) should invest in these types of projects. - the basic research has a benefit, and may lead to other discoveries - if they happen to achieve fusion, the benefit to humanity will be enormous There must be "moonshot" projects, like when we originally went to the moon, an unpractical journey.
sam 6y ago
There are a few reasons why the investment is flowing. 1) New enabling technologies, including high temperature superconducting tape, algorithms for plasma control and diagnostics which take advantage of new hardware (GPUs), and advanced manufacturing techniques are now available. 2) Optimism that private companies can synthesize the past 70 years of plasma physics research with these enabling technologies to develop transformative approaches to fusion. If you're interested I wrote a short article about this topic a few months ago, https://www.fusionenergybase.com/article/the-number-of-fusion-energy-startups-is-growing-fast-heres-why/ https://www.fusionenergybase.com/article/the-number-of-fusio...
- moneytide1 6y ago
  I remember reading recently that a Nobel Prize was won a few years ago for work with chirped pulse laser amplification using titanium sapphire lasers that can apparently achieve nano or microsecond energy pulses in the terawatt range. A potential contender for a non-fission fusion spark, but still does not solve the containment problem. The article says the laser could generate a magnetic field somehow? https://newatlas.com/energy/hb11-hydrogen-boron-fusion-clean-energy/ https://newatlas.com/energy/hb11-hydrogen-boron-fusion-clean...
  - DennisP 6y ago
    Here's the last of a great series of articles on that idea (with links to the earlier articles): https://asiatimes.com/2020/05/meet-the-father-of-the-hydrogen-boron-laser-fusion-reactor/ https://asiatimes.com/2020/05/meet-the-father-of-the-hydroge... And a startup hoping to try it, run by the guy who came up with the idea decades ago: https://www.hb11.energy/ https://www.hb11.energy/ There are several groups doing experiments with it, and it seems to be going really well. There are two lasers. One hits a target that generates a magnetic field; it'd be hard to describe without a picture but see the articles at the first link. Basically the laser blasts electrons off a metal surface, they hit another surface and flow through a coil. For a nanosecond there's a 4000 tesla field. (An MRI machine generates around 3 tesla.) The second laser is faster and more powerful: 10 petawatts or more, for only a picosecond. That hits the fuel. It's enough to kick off fusion by itself, but the magnetic containment creates an avalanche effect that multiplies output. Then it all blows up, you harvest the energy and cycle in another target.

PopePompus 6y ago

Sadly, that huge fusion plant is offline half the time for any given location on the Earth, and is severely degraded by cloudy weather. Also using it to power the world will require large areas of land to be dedicated to collecting its output.

LargoLasskhyfv 6y ago
So what? I give you Space Grid ©. [1] https://en.wikipedia.org/wiki/Space-based_solar_power https://en.wikipedia.org/wiki/Space-based_solar_power edit: I don't know why that symbol doesn't show as copyleft as intended.
- bufbupa 6y ago
  That seems like it could have more difficult engineering problems than a fusion reactor! Seems like a quick way to accidentally microwave a desert into a sea of glass. Hope you don't put anything remotely near the power receiver on earth.
  - DennisP 6y ago
    Power density on the ground would be way lower than you're thinking. The leading proposals, like SPS-Alpha, put a gigawatt-scale power station in geostationary orbit. Power is beamed to ground via microwave. The receiver station has to be kilometers wide, which puts the power density low enough so birds wouldn't be harmed; even that amount of focus is only doable by sending a pilot signal from the receiver, so the beam can't trivially be redirected to other targets. Despite its size, the receiver would be inexpensive, since it's mostly wire antennae.
  - rob74 6y ago
    Hey, think positive! If microwaves prove too dangerous, and they finally do manage to build a cable from the orbital power station down to earth, they have a space elevator as well!
- mrec 6y ago
  Space advocates seem to have been going off the idea of that over the past few years. I'm not sure how much of that is due to a better appreciation of the downsides, and how much is due to the very rapid improvements we've been seeing in ground-based solar. A couple of recent (late 2019) articles from Casey Handmer: https://caseyhandmer.wordpress.com/2019/08/20/space-based-solar-power-is-not-a-thing/ https://caseyhandmer.wordpress.com/2019/08/20/space-based-so... https://caseyhandmer.wordpress.com/2019/09/20/no-really-space-based-solar-power-is-not-a-useful-idea-literature-review-edition/ https://caseyhandmer.wordpress.com/2019/09/20/no-really-spac... It's worth reading the comments too; there are some interesting points there, although I think the game-changing ones rely on new tech and/or well-developed lunar industry.
  - LargoLasskhyfv 6y ago
    Yes. I'm aware of that. But while economically usable fusion remains SciFi so far, space based solar just lacks some bootstrapping. Which seems to be more attainable as time passes. If "we" really wanted this, we could do it now because the technology is there. There is no what if like in any path to fusion. edit: especially considering all the hype about colonizing Mars, or a Moonbase.
  - pfdietz 6y ago
    Space solar is a way to get the most out of expensive PV cells. But PV is no longer expensive. It's cheaper to just overbuild on Earth and transmit energy through time (storage) rather than through space (microwaves).
barbegal 6y ago
There are other options for using the sun's energy. We can grow trees to burn, we can optimise windows and window coverings to use solar energy to heat and cool buildings, we can put solar panels in the dessert, or in the ocean, or above roads or in space (but that's not very cost effective). My go to book on energy is this one http://www.withouthotair.com/ http://www.withouthotair.com/ It gives good numbers for all the energy that we could generate from renewables and all the energy we currently use.
networkimprov 6y ago
High-altitude solar platforms: http://www.stratosolar.com/blog http://www.stratosolar.com/blog
adrianhel 6y ago
There is a lot of land in the world. And definitely have the capacity to build the supply chains. It's just that it's slow and expensive while oil, gas and nuclear is fast and cheap. We need policy changes. Or in a very ideal world, fusion.
- pfdietz 6y ago
  New solar is much cheaper than new nuclear, per kWh.
  - adrianhel 6y ago
    I did not know that. That's great!
    - pfdietz 6y ago
      It's startling how quickly this happened. Even ten years ago it wasn't true. Many people have not updated their priors yet and still think nuclear is a realistic option. At this point, nuclear is a long shot, which is why I refer to SMRs as HMRs, "Hail Mary Reactors".

regularfry 6y ago

The one that gave me most hope from this point of view was the Polywell design. It made some waves a few years ago then got classified and sputtered out, then this happened: https://en.wikipedia.org/wiki/Polywell#%22Final_nail%22 https://en.wikipedia.org/wiki/Polywell#%22Final_nail%22? I'm entirely with you as far as tokamaks go - they're relying on unobtainium for a significant component - but I think other designs are possible, just under-researched.

MauranKilom 6y ago
Are you aware of https://en.wikipedia.org/wiki/Wendelstein_7-X https://en.wikipedia.org/wiki/Wendelstein_7-X? It is well on its way to produce sustained plasma discharges of multiple minutes. The stellarator design has some decisive advantages over Tokamaks.
- pfdietz 6y ago
  It does not avoid the generic problem of DT fusion reactors, which is lousy power density. The magnets are also famously complex and expensive.
  - MauranKilom 6y ago
    That sounds like engineering and scaling challenges, not inherent limitations... I mean, they clearly have the magnets figured out and so far there doesn't seem to have been a lot in the way of unforeseen roadblocks.
    - pfdietz 6y ago
      That sounds like the dismissive attitude a plasma physicist, for whom mere engineering issues are trivial and of lesser importance. But engineering issues are perfectly capable of ruining the prospects for a technology. Fission, for example, faces nothing BUT engineering issues (where cost is considered a part of engineering.) The equivalent of breakeven and ignition was achieved for fission in 1942. DT fusion faces fundamental engineering obstacles, obstacles that are not solvable by tweaking the confinement scheme. Scaling up makes the main problem, power density, worse, not better (see a later comment by me on this issue.)

nickparker 6y ago

Have you seen General Fusion? They spin a large ball of molten lead using pumps and shoot hot plasma into the vortex that forms in the middle, then strike the walls of the lead chamber with carefully timed steam pistons to make an implosion pressure wave not entirely unlike Fat Man’s design, except reusable and for fusion. The fusion heat and radiation gets absorbed by the lead and they run a heat exchanger on the pump loop for power generation. They also think they can breed fuel with some lithium in the lead. I love their plan aesthetically but I’m not qualified to judge how feasible it is. It’s very satisfyingly physical though.

ColanR 6y ago
Do you know if they've achieved fusion yet? I remember reading about them in PopSci way back in the day, and wondered how they were doing.
teachrdan 6y ago
Do you end up with a huge ball of radioactive lead at the end of the day? From what little I know of fusion, it seems you still end up with irradiated lead or other shielding. (And yes, I know that coal releases radiation, and that the installation of solar panels and wind turbines is, currently, a dangerous job, etc.)
- nickparker 6y ago
  Huh, I suppose you do! I had a naive short-circuit in my head that "neutron flux is bad because it destroys your your materials. If your material is molten lead anyway who cares?" I also didn't know lead has such a low neutron absorption cross section. For what it's worth lead with extra neutrons seems a lot less scary than eg uranium fission waste. Stable isotopes 206, 207, and 208 represent 98% by abundance, 208 has the lowest cross section, and 209 has a 3 hour half-life into Bismuth-209 which is nearly stable (2e19 year half-life). So it seems almost all of your neutron captures just make other stable lead isotopes or briefly-terrifying 209 that's totally safe after a couple days. You only get real scary stuff if the trace amounts of undecayed 209 manage a second capture. Edit: I should add they want to mix lithium into the lead to absorb neutrons and regenerate fuel

m463 6y ago

> I don't see why anyone (including governments) should invest in these types of projects. - the basic research has a benefit, and may lead to other discoveries - if they happen to achieve fusion, the benefit to humanity will be enormous There must be "moonshot" projects, like when we originally went to the moon, an unpractical journey.

sam 6y ago

There are a few reasons why the investment is flowing. 1) New enabling technologies, including high temperature superconducting tape, algorithms for plasma control and diagnostics which take advantage of new hardware (GPUs), and advanced manufacturing techniques are now available. 2) Optimism that private companies can synthesize the past 70 years of plasma physics research with these enabling technologies to develop transformative approaches to fusion. If you're interested I wrote a short article about this topic a few months ago, https://www.fusionenergybase.com/article/the-number-of-fusion-energy-startups-is-growing-fast-heres-why/ https://www.fusionenergybase.com/article/the-number-of-fusio...

moneytide1 6y ago
I remember reading recently that a Nobel Prize was won a few years ago for work with chirped pulse laser amplification using titanium sapphire lasers that can apparently achieve nano or microsecond energy pulses in the terawatt range. A potential contender for a non-fission fusion spark, but still does not solve the containment problem. The article says the laser could generate a magnetic field somehow? https://newatlas.com/energy/hb11-hydrogen-boron-fusion-clean-energy/ https://newatlas.com/energy/hb11-hydrogen-boron-fusion-clean...
- DennisP 6y ago
  Here's the last of a great series of articles on that idea (with links to the earlier articles): https://asiatimes.com/2020/05/meet-the-father-of-the-hydrogen-boron-laser-fusion-reactor/ https://asiatimes.com/2020/05/meet-the-father-of-the-hydroge... And a startup hoping to try it, run by the guy who came up with the idea decades ago: https://www.hb11.energy/ https://www.hb11.energy/ There are several groups doing experiments with it, and it seems to be going really well. There are two lasers. One hits a target that generates a magnetic field; it'd be hard to describe without a picture but see the articles at the first link. Basically the laser blasts electrons off a metal surface, they hit another surface and flow through a coil. For a nanosecond there's a 4000 tesla field. (An MRI machine generates around 3 tesla.) The second laser is faster and more powerful: 10 petawatts or more, for only a picosecond. That hits the fuel. It's enough to kick off fusion by itself, but the magnetic containment creates an avalanche effect that multiplies output. Then it all blows up, you harvest the energy and cycle in another target.