If we're in the fictional world where any production above a perfectly constant baseline (with the occasional two month break for refuelling where fairies power everything) has zero utility, that excess is worthless isn't it?

There's only so far you can take these counterfactuals, but presumably you'd be selling it at, say, $10/MWh (because things like hydrogen are already profitable at this cost) which might cover part of the distribution costs (which are not in that model) and bring it down to roughly on par.

If it really is on par, then even the stupidest approach to renewables (i.e. massively over-building instead of using some storage) is equal cost to nuclear. That's a strong case for renewables.

It's really hard to overstate how much better the case for renewables is than the competition.

That said, there are a bunch of risks and externalised costs in a zero storage strategy not captured by simple prices. Many of the objections of the nuclear industry are actually true in such a scenario.

Overbuilding solar 4-8x with current tech would cause alot of CO2 emissions from silicon refining, it would strain silver and copper supplies. Overbuilding wind by a similar amount would require vast amounts of steel, strain niobium production, and cause CO2 emissions from concrete. Even if your system was on par with nuclear on a dollar basis, it would still produce too many emissions (half or more of 100% gas) and quite fragile.

Relying on cross continent links to reduce overbuild ratio is a massive strategic risk, and if someone in the chain does a texas and has a bunch of equipment fail, you'd have a real version of the scenario the anti-wind campaogners are imagining in europe right now.

A good strategy is a mix of everything aiming to remove as many emissions with each dollar spent. If that means aiming initially for 50% net solar availability, and 30% net wind availability with 20% surplus and keeping the gas turbines running through winter to provide the remaining 40% for a few years whilst shotgunning money at research for abundant batteries, electrolysers, and tidal to see which one sticks, then that is far better than using the same funds to pay for 20% nuclear that will be online in 2050.

Another good strategy would be to build out scalable storage (thermal batteries, electrolysers and pumped hydro) immediately and go all in on wind/solar asap. The amount of concrete required for the pumped storage might he prohibitive though and it won't cost a great deal less than nuclear (although it will be online sooner).

Even a strategy with 10-20% nuclear like what China is pursuing is tolerable (including the very likely chernobyl scale incidents that will happen if it's pursued worldwide -- which are vastly preferable to the consequences of coal) in countries that aren't controlled by neoliberal systems which are fundamentally incapable of operating any large scale project that won't pay off visibly in an election cycle. It's just the constant shouting of "stop all the wind and only build nuclear" that's imbecilic.