Somebody with one leg can do a lot better in a race than somebody with none, but that is not the measure to consider when the competition is with two-legged runners. (Hint: they win.)
So if any of fusion startups can make operating plant within the next 20 years, it can be used. But if that takes longer, then I agree that large-scale fusion will not happen.
Heating and lamp gas composed of of hydrogen and carbon monoxide (!) were once delivered throughout cities through cast-iron plumbing. That was displaced by "natural gas" as increasing numbers of people were found to have been asphyxiated after a lamp flame in their house died, typically from a pressure fluctuation.
Natural gas then had to have mercaptan odorants added after leaking gas accumulated undetected and exploded. Then, valves that would only stay open when hot came into regular use, for pilot lights. Now pilot lights are gone, replaced by spark generators. Hydrogen will displace natural gas in industrial settings, but synthetic methane or propane will probably be needed for domestic use.
I'll add that the alternative proposal, excess renewables with curtailment, has 0% efficiency on the curtailed power. Using that power for anything at all, including making hydrogen, is more efficient that just dropping it on the ground.
But hydrogen is very far from the only storage choice, it is just one that is attractive for numerous ancillary reasons: we need to make the hydrogen regardless, so might as well store it too.
Yes, making magnetic fields stronger can give one higher power density than ITER. But one runs into a limit because of power density at the wall. Once you're at that limit, higher magnetic fields don't really help.
ARC's volumetric thermal power density (volume of reactor, not of the plasma) is just 1/40th that of the primary reactor vessel of a commercial pressurized water fission reactor.
60% of the mass of an ARC reactor is in the steel structural supports for the magnets, so it's about at the upper limit for steady magnetic fields in a fusion reactor.
Plus a fusion plant can be very quick to start and shutdown or throttle down which is very useful for base load.
You don't need to separate all the different parts. You reprocess our old waste into fuel for modern reactors. In those reactors higher actinides will be burned up. And the resulting output does not have higher actinides and only needs to be stored as long.
Moltex Energy is currently engaged with the Canadian regulator for such a facility, the process is called WATSS. Doing this is actually cheaper then the deep storage storage facilities proposed in many countries. Sadly because of political bullshit reprocessing has been made illegal in the US.
Such things would have been doable decades ago, and the money for it is already on bank accounts in most countries. But politician force the 'dig a hole for everything' solutions instead.
> Plus a fusion plant can be very quick to start and shutdown or throttle down which is very useful for base load.
Next generation fusion would also be very reactive to changes. Far more then traditional.
But the reality is you actually want to run full power as much as you can, no matter if fission or fusion.
Fusion solves a minor problem of fission while making the major problem worse. It's a great example of misplaced focus.
Cooling down the magnets of a fusion plant is not a quick process, btw. Hell, just getting a fusion plant built with RAFM steel up to operating temperature is a delicate process. Once irradiated, the temperature window that material can operate at is rather narrow (300 C to 550 C; below that it's too brittle and above that it creeps.)
If you can build a nuclear plant with 500MW output and reduce the amount of concrete needed by significant factor, all of a sudden your are quite competitive.
Just for comparison, this is one of the furthest along commercial GenIV projects designs:
https://www.youtube.com/watch?v=1pZC_ajI8Hs
No massive cooling towers. No gigantic containment cylinder. No gigantic low-pressure steam turbine.
In a PWR the core containment vessel is incredibly expensive and can only be built a few places, but its actually not the cost driver. Even so, compare to those, modern GenIV core vessels are vastly cheaper.
Not having to weld 8 inch gigantic steel vessels is far easier. See:
[1] - https://en.m.wikipedia.org/wiki/SPARC_(tokamak)