5 ms·

This is perhaps an obvious question to some, but I'll ask it anyway: How is the power generated here converted into usable electricity? I know for conventional

This is perhaps an obvious question to some, but I'll ask it anyway: How is the power generated here converted into usable electricity? I know for conventional fission reactors the heat of fission is basically used to run a steam turbine. Given the extreme heat of the plasma, and that it must be magnetically suspended so that it doesn't even touch the sides of the containment, how is that heat transferred to some other medium to generate electricity?

Etheryte 3y ago
I'm not sure if it's the case for this specific reactor, but the common answer to this question is that you need cooling in the surrounding walls and the coolant that runs through the walls transfers the heat out where it can be used to do useful work.
peteradio 3y ago
You still get heat transfer from uncharged elements I guess.
WJW 3y ago
Given that the plasma is several million degrees, it will radiate a lot of energy and heat up the walls even if it does not directly touch them. Just cooling the walls can heat up the cooling fluid enough to later produce steam with. AFAIK the Wendelstein machine is not configured for electricity production though, so the cooling is just cooling atm.
- jeffbee 3y ago
  > Given that the plasma is several million degrees, it will radiate a lot of energy That doesn't entirely follow. 2 particles whizzing past each other at relativistic speeds have extreme temperatures but don't offer much energy. Mass is in this equation.
  - willis936 3y ago
    What if you have 10^20 particles? Each charged particle emits photons with energy/frequency proportional to their speed (Bremsstrahlung). This is mostly from electrons because they are much lighter and so are much hotter/faster. Plasmas are quasineutral though so you'll have those electrons present. There is a long line of research trying to get away from that constraint with little luck so far (but it should continue to be worked on!). Jumpjng back up the stack: photon radiation is mostly considered a loss since it transfers energy out of confinement and does not impart it on other fuel. You nominally extract your heat via neutrons: same as fission reactors. Some designs (Helion) aim for reactions with charged byproducts. The reaction produces a current that can be coupled by a surrounding coil, much like a transformer but powered by current induced by plasma rather than another copper wire.
fizigura 3y ago
They currently run a bad-ass heatsink (which is one of the main challenges of this project, i.e., how to cool it), but eventually you will use that heat to convert it into electricity, yes. For the German-speaking crowd here, the Alternativlos podcast guys were there twice and had lengtly conversations with the researchers there. Like, between nerds. Really cool, if you understand the language. https://alternativlos.org/36/ https://alternativlos.org/36/ (from 2016) https://alternativlos.org/51/ https://alternativlos.org/51/ (most recent, from may 2023)
- drannex 3y ago
  Omega Tau also visited and talked with some of the researchers and has a great podcast episode on it (and truth be told, all of their episodes are great). https://omegataupodcast.net/312-the-wendelstein-7-x-fusion-experiment/ https://omegataupodcast.net/312-the-wendelstein-7-x-fusion-e... (from 2019, 3Hrs, English)
2-718-281-828 3y ago
probably boiling water and the steam drives turbines whose coils and rotating magnets produce electricity.
idiotsecant 3y ago
Yes, the boring and actually feasible answer is steam. But it sure is fun to dream! https://en.wikipedia.org/wiki/Direct_energy_conversion https://en.wikipedia.org/wiki/Direct_energy_conversion
- midasuni 3y ago
  Isn’t one of the problems with nuclear that it increases water temperature in rivers
  - jjk166 3y ago
    The reverse actually. Reactors need to be shut down when rivers get too warm because they are not able to properly cool the reactor. Nuclear reactors don't produce anywhere near enough energy to heat a large river by a measurable amount.
  - calfuris 3y ago
    That's a problem associated with a particular cooling system design, so it's more of a thermal power problem than a nuclear power problem.
    - midasuni 3y ago
      Ok so wouldn’t it be a problem with a fusion/thermal system too?
jtriangle 3y ago
Same way most electricity is made, you use the energy created to heat up water into high pressure steam, high pressure steam turns a turbine(s) which turn gensets that produce 3 phase AC current. This one in particular isn't setup to do that, and as far as I know, none are yet. It's a pretty simple engineering problem, and, until we can maintain fusion for months at a time, it's not really something that needs to be built. There is, however, one fusion concept that shows some promise that doesn't require all that that helion energy is developing (helionenergy.com) they're yet to create net-power, but, their idea has some promise, and avoids the common problems with other forms of fusion power. I don't really see it as the be-all to end-all in the space, but from what I can tell they very well might be the stopgap that is needed between large scale stellerators and fission.
tsimionescu 3y ago
Most of the answers are missing the actual (proposed) mechanism. The energy of the reaction is mostly carried away as high-energy neutrons. So, the way to get energy back is to "capture" those neutrons. Since neutrons are not electrically charged, you can't use them to directly create electricity, so all you're left with is using them for heat. Unfortunately, since they are electrically neutral, they're also relatively hard to catch. You need a dense material where they will have a good chance to hit some nucleus. The proposed designs are typically some kind of liquid metal blanket being circulated around the reactor and onto a place where it can boil water to produce steam to spin a turbine. Lithium is the metal most proposed for this, since it also has the advantage that it can produce tritium when bombarded with neutrons (tritium being the super rare half of the fuel that goes into the reaction).
- nerdponx 3y ago
  It's always fascinating to me that, no matter how many interesting new ways to release lots of energy we develop, we are still stuck with the same method for converting it to electricity: release the energy as heat, use heat to make steam, use steam to drive generator.
  - NateEag 3y ago
    Helion is planning to use induction to generate electricity from the fusion reaction's generated magnetic field, IIUC: https://www.helionenergy.com/faq/ https://www.helionenergy.com/faq/ (See "How does Helion generate electricity from fusion?" question)
    - MichaelZuo 3y ago
      Which doesn't make sense for power generation since there will always be some percentage of neutrons produced by any type of fusion reaction that can only be useful for generating steam. To entirely skip the steam cycle portion is to intentionally make a much less efficient design. For space-constrained, high-value, applications where economics don't matter that much, such as a submarine, that would make sense, but otherwise...
mdprock 3y ago
here there is no power generated as it's not working with deuterium-tritium. most of the heating will heat the plasma and a fraction of this will reach the cooling system. To make a comparison ITER is expected to have 50 MW heating for 400 seconds approx. = 20 GJoule. Using a DT mix will result though in 500 MW Fusion Power

Etheryte 3y ago

I'm not sure if it's the case for this specific reactor, but the common answer to this question is that you need cooling in the surrounding walls and the coolant that runs through the walls transfers the heat out where it can be used to do useful work.

peteradio 3y ago

You still get heat transfer from uncharged elements I guess.

WJW 3y ago

Given that the plasma is several million degrees, it will radiate a lot of energy and heat up the walls even if it does not directly touch them. Just cooling the walls can heat up the cooling fluid enough to later produce steam with. AFAIK the Wendelstein machine is not configured for electricity production though, so the cooling is just cooling atm.

jeffbee 3y ago
> Given that the plasma is several million degrees, it will radiate a lot of energy That doesn't entirely follow. 2 particles whizzing past each other at relativistic speeds have extreme temperatures but don't offer much energy. Mass is in this equation.
- willis936 3y ago
  What if you have 10^20 particles? Each charged particle emits photons with energy/frequency proportional to their speed (Bremsstrahlung). This is mostly from electrons because they are much lighter and so are much hotter/faster. Plasmas are quasineutral though so you'll have those electrons present. There is a long line of research trying to get away from that constraint with little luck so far (but it should continue to be worked on!). Jumpjng back up the stack: photon radiation is mostly considered a loss since it transfers energy out of confinement and does not impart it on other fuel. You nominally extract your heat via neutrons: same as fission reactors. Some designs (Helion) aim for reactions with charged byproducts. The reaction produces a current that can be coupled by a surrounding coil, much like a transformer but powered by current induced by plasma rather than another copper wire.

fizigura 3y ago

They currently run a bad-ass heatsink (which is one of the main challenges of this project, i.e., how to cool it), but eventually you will use that heat to convert it into electricity, yes. For the German-speaking crowd here, the Alternativlos podcast guys were there twice and had lengtly conversations with the researchers there. Like, between nerds. Really cool, if you understand the language. https://alternativlos.org/36/ https://alternativlos.org/36/ (from 2016) https://alternativlos.org/51/ https://alternativlos.org/51/ (most recent, from may 2023)

drannex 3y ago
Omega Tau also visited and talked with some of the researchers and has a great podcast episode on it (and truth be told, all of their episodes are great). https://omegataupodcast.net/312-the-wendelstein-7-x-fusion-experiment/ https://omegataupodcast.net/312-the-wendelstein-7-x-fusion-e... (from 2019, 3Hrs, English)

2-718-281-828 3y ago

probably boiling water and the steam drives turbines whose coils and rotating magnets produce electricity.

idiotsecant 3y ago

Yes, the boring and actually feasible answer is steam. But it sure is fun to dream! https://en.wikipedia.org/wiki/Direct_energy_conversion https://en.wikipedia.org/wiki/Direct_energy_conversion

midasuni 3y ago
Isn’t one of the problems with nuclear that it increases water temperature in rivers
- jjk166 3y ago
  The reverse actually. Reactors need to be shut down when rivers get too warm because they are not able to properly cool the reactor. Nuclear reactors don't produce anywhere near enough energy to heat a large river by a measurable amount.
- calfuris 3y ago
  That's a problem associated with a particular cooling system design, so it's more of a thermal power problem than a nuclear power problem.
  - midasuni 3y ago
    Ok so wouldn’t it be a problem with a fusion/thermal system too?

jtriangle 3y ago

Same way most electricity is made, you use the energy created to heat up water into high pressure steam, high pressure steam turns a turbine(s) which turn gensets that produce 3 phase AC current. This one in particular isn't setup to do that, and as far as I know, none are yet. It's a pretty simple engineering problem, and, until we can maintain fusion for months at a time, it's not really something that needs to be built. There is, however, one fusion concept that shows some promise that doesn't require all that that helion energy is developing (helionenergy.com) they're yet to create net-power, but, their idea has some promise, and avoids the common problems with other forms of fusion power. I don't really see it as the be-all to end-all in the space, but from what I can tell they very well might be the stopgap that is needed between large scale stellerators and fission.

tsimionescu 3y ago

Most of the answers are missing the actual (proposed) mechanism. The energy of the reaction is mostly carried away as high-energy neutrons. So, the way to get energy back is to "capture" those neutrons. Since neutrons are not electrically charged, you can't use them to directly create electricity, so all you're left with is using them for heat. Unfortunately, since they are electrically neutral, they're also relatively hard to catch. You need a dense material where they will have a good chance to hit some nucleus. The proposed designs are typically some kind of liquid metal blanket being circulated around the reactor and onto a place where it can boil water to produce steam to spin a turbine. Lithium is the metal most proposed for this, since it also has the advantage that it can produce tritium when bombarded with neutrons (tritium being the super rare half of the fuel that goes into the reaction).

nerdponx 3y ago
It's always fascinating to me that, no matter how many interesting new ways to release lots of energy we develop, we are still stuck with the same method for converting it to electricity: release the energy as heat, use heat to make steam, use steam to drive generator.
- NateEag 3y ago
  Helion is planning to use induction to generate electricity from the fusion reaction's generated magnetic field, IIUC: https://www.helionenergy.com/faq/ https://www.helionenergy.com/faq/ (See "How does Helion generate electricity from fusion?" question)
  - MichaelZuo 3y ago
    Which doesn't make sense for power generation since there will always be some percentage of neutrons produced by any type of fusion reaction that can only be useful for generating steam. To entirely skip the steam cycle portion is to intentionally make a much less efficient design. For space-constrained, high-value, applications where economics don't matter that much, such as a submarine, that would make sense, but otherwise...

mdprock 3y ago

here there is no power generated as it's not working with deuterium-tritium. most of the heating will heat the plasma and a fraction of this will reach the cooling system. To make a comparison ITER is expected to have 50 MW heating for 400 seconds approx. = 20 GJoule. Using a DT mix will result though in 500 MW Fusion Power