3 ms·

It sure might be faster to experiment with new tech if your reactor is toy-sized, but building the whole thing at a scale that's somewhat realistic for economic

It sure might be faster to experiment with new tech if your reactor is toy-sized, but building the whole thing at a scale that's somewhat realistic for economically generating power seems an un-avoidable step to me. ITER is doing that NOW and NONE of headline-generating startups have even started... So it seems to me that ITER is both contributing more engineering insights and closer towards a full-fledged fusion power-plant, and unlikely to be overtaken in these regards anytime soon, if ever.

DennisP 4y ago
Tokamak output scales with the square of plasma volume, but the fourth power of magnetic field strength. Double the field, 16X the output. We have superconductors now that can support much stronger magnetic fields than ITER uses. That lets us build smaller tokamaks with the same output as ITER. Several startups are using them, led by MIT spinoff CFS. Their SPARC reactor should have output similar to ITER's, in a reactor half the size of JET, which was built in a year. They expect to attempt net power in 2025 and a lot of researchers think they'll succeed. Assuming that works, as similar reactor the size of JET gets them to commercial output levels.
- myrmidon 4y ago
  My point is that ITER is designed for 500MW (thermal) output. SPARC aims for something around 100MW (and is even further from continuous operation than ITER by design), and even the ARC successor (which is currently basically a pipe dream) is going to catch up with ITER in output power at best. So even IF the whole SPARC thing goes according to play, it's going to be miles away from anything resembling a competitive power plant, while ITER is potentially something like a quarter way there (assuming that operating at 2GW thermal begins being somewhat attractive/feasible for a fusion-powerplant). Personally, I strongly doubt that fusion power is EVER going to be an option because of simple economics; I just don't really see how a vacuum chamber surrounded by superconducting magnets, cooling systems, turbines and turbogenerators is ever going to compete (financially) with just slapping PV panels on a roof, putting some battery banks in the basement, hooking it up with an inverter and just repeating as necessary until power demands are met...
  - DennisP 4y ago
    Bigger is better only if it gives you a better ratio of capital expense to output. Due to the magnetic scaling I mentioned, SPARC/ARC probably does significantly better on that front.
    - myrmidon 4y ago
      My point is that any commercial plant MUST be big enough to supply a generic steam turbine setup with heat; every fusion reactor design that cant achieve that is just a glorified toy, because it CANT operate economically. A bigger research reactor is simply better in that it enables you to investigate/solve problems that are related to scale, and all those MUST be solved before a commercial plant can be built. Until ARC or an even further removed successor catches up to ITER in size/power, the SPARC project is just yet another toy reactor IMO.
      - DennisP 4y ago
        The US has 37 coal plants below 10MW, 73 plants from 50 to 100MW, and 85 plants between 100 and 250MW: https://www.gem.wiki/Existing_U.S._Coal_Plants#Size_comparison_of_coal_plants https://www.gem.wiki/Existing_U.S._Coal_Plants#Size_comparis... Coal plants of course use steam turbines: https://www.tva.com/energy/our-power-system/coal/how-a-coal-plant-works https://www.tva.com/energy/our-power-system/coal/how-a-coal-...
        myrmidon 4y ago
        Do you honestly believe that fusion power plants smaller than ITER (500MW thermal) could ever be economically viable, or are you just playing devils advocate? Because your chart cements my point: Power produced by coal plants smaller than ITER (<500MW thermal output, or <250MW electrical power in your chart) is negligible because building those makes evidently no sense economically (almost all installed capacity is in big plants). And thats with coal where building smaller actually reduces operating cost from fuel (unlike fusion) plus needs no vacuum chamber, cryocooling or dealing with neutron activation...

DennisP 4y ago

Tokamak output scales with the square of plasma volume, but the fourth power of magnetic field strength. Double the field, 16X the output. We have superconductors now that can support much stronger magnetic fields than ITER uses. That lets us build smaller tokamaks with the same output as ITER. Several startups are using them, led by MIT spinoff CFS. Their SPARC reactor should have output similar to ITER's, in a reactor half the size of JET, which was built in a year. They expect to attempt net power in 2025 and a lot of researchers think they'll succeed. Assuming that works, as similar reactor the size of JET gets them to commercial output levels.

myrmidon 4y ago
My point is that ITER is designed for 500MW (thermal) output. SPARC aims for something around 100MW (and is even further from continuous operation than ITER by design), and even the ARC successor (which is currently basically a pipe dream) is going to catch up with ITER in output power at best. So even IF the whole SPARC thing goes according to play, it's going to be miles away from anything resembling a competitive power plant, while ITER is potentially something like a quarter way there (assuming that operating at 2GW thermal begins being somewhat attractive/feasible for a fusion-powerplant). Personally, I strongly doubt that fusion power is EVER going to be an option because of simple economics; I just don't really see how a vacuum chamber surrounded by superconducting magnets, cooling systems, turbines and turbogenerators is ever going to compete (financially) with just slapping PV panels on a roof, putting some battery banks in the basement, hooking it up with an inverter and just repeating as necessary until power demands are met...
- DennisP 4y ago
  Bigger is better only if it gives you a better ratio of capital expense to output. Due to the magnetic scaling I mentioned, SPARC/ARC probably does significantly better on that front.
  - myrmidon 4y ago
    My point is that any commercial plant MUST be big enough to supply a generic steam turbine setup with heat; every fusion reactor design that cant achieve that is just a glorified toy, because it CANT operate economically. A bigger research reactor is simply better in that it enables you to investigate/solve problems that are related to scale, and all those MUST be solved before a commercial plant can be built. Until ARC or an even further removed successor catches up to ITER in size/power, the SPARC project is just yet another toy reactor IMO.
    - DennisP 4y ago
      The US has 37 coal plants below 10MW, 73 plants from 50 to 100MW, and 85 plants between 100 and 250MW: https://www.gem.wiki/Existing_U.S._Coal_Plants#Size_comparison_of_coal_plants https://www.gem.wiki/Existing_U.S._Coal_Plants#Size_comparis... Coal plants of course use steam turbines: https://www.tva.com/energy/our-power-system/coal/how-a-coal-plant-works https://www.tva.com/energy/our-power-system/coal/how-a-coal-...
      - myrmidon 4y ago
        Do you honestly believe that fusion power plants smaller than ITER (500MW thermal) could ever be economically viable, or are you just playing devils advocate? Because your chart cements my point: Power produced by coal plants smaller than ITER (<500MW thermal output, or <250MW electrical power in your chart) is negligible because building those makes evidently no sense economically (almost all installed capacity is in big plants). And thats with coal where building smaller actually reduces operating cost from fuel (unlike fusion) plus needs no vacuum chamber, cryocooling or dealing with neutron activation...