>That does not prevent wind and solar from providing an all-renewable grid.

Yes, it does. Which part of "there is no alternative to natural gas for base-load" are you purposely ignoring?

>That the backup "today, is natural gas" is not relevant to that question.

It is if there is no path past natural gas. What if there is no other alternative?

What if there is no path past natural gas. What if natural gas is not an intermediate technology on the path to utopia, but it is the end-state. Germany certainly acts like that is true because Germany inked a multi-decade deal with Russia to build pipelines and import their gas for the next 5 decades.

>Use of Li-ion batteries for long term storage is a strawman brought up by persons who are attempting to throw shade on renewables.

It's a strawman to you but there are people who really truly believe that Li-ion batteries can provide long-term grid-scale storage. And they will argue with you as vehemently as you argue for hydrogen. Every renewable proponent has its pet unproven technology as the saviour. It's a necessary part of the renewable religion

>Long term storage would be much better done with hydrogen (trading lower efficiency for lower capital cost).

Hydrogen is not a solution, or it's as much a solution as any other unproven pipe-dream. It is not used today because hydrogen for long-term grid-scale storage is an insanely challenging proposition both from generation to storage (Hydrogen needs to be stored under high pressures, thereby requiring reinforced/heavy containers). But every proponent of renewable religion will have their favourite Saint they can pray too. For some, it is Li-ion batteries. For you, it's hydrogen storage.

>Because the effective CO2 tax isn't high enough yet

That's your personal assessment? How about the fact that there is no proven natural-gas alternative to base-load? The laws of thermodynamics don't care about carbon taxes. Taxing carbon only works if there is an alternative to move to. You can tax airplane fuel as much as you want, but airplanes will continue to use fossil fuels because there is no alternative.

> to cause the shutdown of existing fossil fuel plants for which capital costs are sunk

We (NA and Europe) have no issues shutting down coal. But we sure as heck are not shutting down natural gas.

>I could well ask "why isn't nuclear displacing natural gas?"

I wish I knew. I really do. It's part of the irrationality of all of this. My guess is that nuclear suffered from 50 years of FUD from environmentalists (helped by Chernobyl and Three Mile Islan), over-regulation and cheap natural gas. So much of the entire green movement is irrational and religious. But to be clear, if it wasn't for CO2 emissions, natural gas would be a perfectly adequate power source.

I'm not concerned about Nuclear costs either, because even though Nuclear is expensive, it is not overly expensive. I think governments should subsidize nuclear. I would say the same about solar/wind if I believed they could actually make a difference.

I leave you with this: Imagine if we doubled-down on nuclear in the 70s to the same level as France did ... Think of the trillions of tons of CO2 emissions that wouldn't have been emitted. It would have bought us maybe an extra 50 years.