7 ms·

>Fusion power is in between the research stage and the commercial stage. The commercial stage ist decades away, there isn't even energy surplus generated in re

>Fusion power is in between the research stage and the commercial stage. The commercial stage ist decades away, there isn't even energy surplus generated in research. No reactor can run longer than some miliseconds, i think you are overly optimistic. Fusion is 20 years away since 50 years.

pfdietz 7y ago
Actually large tokamaks have discharges lasting much more than "some milliseconds" (unless "some" is taken to be some large number :)). But, even if we had solved plasma problems for continuous operation with Q >> 1, the economics of fusion look even worse than fission. The lesser scientific problems of reaching breakeven and ignition are concealing the greater problems of making it worth doing at all.
- nmca 7y ago
  Could you elaborate on the economics? My internal model has always been "1 Joule -> Water -> Hydrogen -> Fusion Reactor -> (1 + epsilon) Joules" was a money printing machine for obvious reasons, but I can see that there are lots of hidden assumptions there.
  - pfdietz 7y ago
    Fusion reactors will be much larger and more expensive than fission reactors. Yes, the fuel is potentially cheaper, but fuel is only a minor part of the cost of power from a fission reactor. The cost of the power plant and non fuel operating costs (like, replacing substantial radioactive components of a fusion reactor every few years due to neutron damage) will be much more important. The usual mistake people make in thinking about fusion is to focus on fuel cost and assume, incorrectly, that fuel cost determines the cost of power. The equipment has to be financed and paid for and maintained, and the cost of doing that will dominate.
    - nmca 7y ago
      This sort of thing? https://ieeexplore.ieee.org/document/4323282 https://ieeexplore.ieee.org/document/4323282 My physics is fairly limited, but I'm not familiar of many cases where induced radioactivity has ever been a concern, or neutron bombardment has caused physical damage? Hoping for pointers :)
      - pfdietz 7y ago
        Vaguely, but at much higher radiation doses. Every atom in the first wall of a DT fusion reactor will be knocked out of position by a neutron about once every three days, on average. The material properties will progressively degrade. Metals will swell and become brittle. Some of the atoms will be transmuted, producing new radioactive ones and sometimes hydrogen or helium atoms that will diffuse into defects, forming high pressure gas bubbles. Even in so-called "advanced fuel" reactors, burning a mixture other than DT, there will be enough neutrons to render the reactor structure too radioactive for hands-on maintenance. This will greatly complicate the problem of fixing the reactor if it breaks.
    - sandworm101 7y ago
      Much (most?) of the costs associated with current fusion reactors stems from the fact they are essentially large science experiments. They have wider operational parameters. They are riddled with sensors. Commercial reactors will be built for very specific narrow operating regimes. They will not need all the sensors. They will not be science experiments. They will be far far cheaper than current reactors.
      - opportune 7y ago
        Producing the parts would also become commoditized. A major cost factor in lots of high tech research (see also: spacecraft) is that the parts are made individually, so they need to be designed/engineered/tested roughly individually and built from essentially scratch.
      - pfdietz 7y ago
        If ITER had a turbine and generator attached, and ignoring that it doesn't have a breeding blanket, it would cost about $100/W. This is an order of magnitude higher than fission power plants, and a factor of 30 more than PV (adjusted for capacity factor).
Symmetry 7y ago
The story, for the last 40 years, has always been more "We'll have fusion in 20 years if you fund us" and as far as I can tell might have been true since the funding asked for didn't arrive until ITER was finally funded and it hasn't used up its 20 years yet. The big difference is that advances in superconducting magnets that spun off from MRI research have reduced what "fully funded" can mean, meaning smaller players are getting involved.
- nick_kline 7y ago
  Humans aren't really capable of making 20 year plans to invent new technologies and implement them on a schedule. We don't know enough about how it works, we don't know what of many choices to make. What you can do is keep working to improve it and hope you'll get something useful. But it's silly, obviously not something you can do, to make such a large research project with a 20 year goal and so many unknowns and say we will have it with high likelihood. Research has to work toward broad goals and investigate new areas. In 1900 could you have made a 20 year plan to invent cell phones and all the technology needed for what we have today? No one would suggest that, but you can invest in basic science and engineering and you'll get some useful things along the way, radios, maybe repeaters, ever smaller ones and better batteries. But you don't necessarily get a specific thing.
  - deleted 7y ago
    [deleted]
- sam0x17 7y ago
  That said, NIF has been making incremental progress. I think they gain like 5-10% efficiency every 20 years or so. Eventually they will break 100 and we'll have fusion reactors XD
petschge 7y ago
Wendelstein 7-X currently has done burns up to 26 seconds and the limit is not plasma instabilities, but wall heating. So now they are putting in water cooling and plan to have 30 minute burns within the next 2 years.

pfdietz 7y ago

Actually large tokamaks have discharges lasting much more than "some milliseconds" (unless "some" is taken to be some large number :)). But, even if we had solved plasma problems for continuous operation with Q >> 1, the economics of fusion look even worse than fission. The lesser scientific problems of reaching breakeven and ignition are concealing the greater problems of making it worth doing at all.

nmca 7y ago
Could you elaborate on the economics? My internal model has always been "1 Joule -> Water -> Hydrogen -> Fusion Reactor -> (1 + epsilon) Joules" was a money printing machine for obvious reasons, but I can see that there are lots of hidden assumptions there.
- pfdietz 7y ago
  Fusion reactors will be much larger and more expensive than fission reactors. Yes, the fuel is potentially cheaper, but fuel is only a minor part of the cost of power from a fission reactor. The cost of the power plant and non fuel operating costs (like, replacing substantial radioactive components of a fusion reactor every few years due to neutron damage) will be much more important. The usual mistake people make in thinking about fusion is to focus on fuel cost and assume, incorrectly, that fuel cost determines the cost of power. The equipment has to be financed and paid for and maintained, and the cost of doing that will dominate.
  - nmca 7y ago
    This sort of thing? https://ieeexplore.ieee.org/document/4323282 https://ieeexplore.ieee.org/document/4323282 My physics is fairly limited, but I'm not familiar of many cases where induced radioactivity has ever been a concern, or neutron bombardment has caused physical damage? Hoping for pointers :)
    - pfdietz 7y ago
      Vaguely, but at much higher radiation doses. Every atom in the first wall of a DT fusion reactor will be knocked out of position by a neutron about once every three days, on average. The material properties will progressively degrade. Metals will swell and become brittle. Some of the atoms will be transmuted, producing new radioactive ones and sometimes hydrogen or helium atoms that will diffuse into defects, forming high pressure gas bubbles. Even in so-called "advanced fuel" reactors, burning a mixture other than DT, there will be enough neutrons to render the reactor structure too radioactive for hands-on maintenance. This will greatly complicate the problem of fixing the reactor if it breaks.
  - sandworm101 7y ago
    Much (most?) of the costs associated with current fusion reactors stems from the fact they are essentially large science experiments. They have wider operational parameters. They are riddled with sensors. Commercial reactors will be built for very specific narrow operating regimes. They will not need all the sensors. They will not be science experiments. They will be far far cheaper than current reactors.
    - opportune 7y ago
      Producing the parts would also become commoditized. A major cost factor in lots of high tech research (see also: spacecraft) is that the parts are made individually, so they need to be designed/engineered/tested roughly individually and built from essentially scratch.
    - pfdietz 7y ago
      If ITER had a turbine and generator attached, and ignoring that it doesn't have a breeding blanket, it would cost about $100/W. This is an order of magnitude higher than fission power plants, and a factor of 30 more than PV (adjusted for capacity factor).

Symmetry 7y ago

The story, for the last 40 years, has always been more "We'll have fusion in 20 years if you fund us" and as far as I can tell might have been true since the funding asked for didn't arrive until ITER was finally funded and it hasn't used up its 20 years yet. The big difference is that advances in superconducting magnets that spun off from MRI research have reduced what "fully funded" can mean, meaning smaller players are getting involved.

nick_kline 7y ago
Humans aren't really capable of making 20 year plans to invent new technologies and implement them on a schedule. We don't know enough about how it works, we don't know what of many choices to make. What you can do is keep working to improve it and hope you'll get something useful. But it's silly, obviously not something you can do, to make such a large research project with a 20 year goal and so many unknowns and say we will have it with high likelihood. Research has to work toward broad goals and investigate new areas. In 1900 could you have made a 20 year plan to invent cell phones and all the technology needed for what we have today? No one would suggest that, but you can invest in basic science and engineering and you'll get some useful things along the way, radios, maybe repeaters, ever smaller ones and better batteries. But you don't necessarily get a specific thing.
- deleted 7y ago
  [deleted]
sam0x17 7y ago
That said, NIF has been making incremental progress. I think they gain like 5-10% efficiency every 20 years or so. Eventually they will break 100 and we'll have fusion reactors XD

petschge 7y ago

Wendelstein 7-X currently has done burns up to 26 seconds and the limit is not plasma instabilities, but wall heating. So now they are putting in water cooling and plan to have 30 minute burns within the next 2 years.