But SMRs address the capex costs by reducing time and resources needed to provision them. The "M" stands for "modular" after all, ie components can be built offsite and imported, and capacity can be added incrementally.
That’s the theory, it has yet to be proven in practice.
Even by their own claims, the caped may be smaller but the $/MWh is substantially higher than large plants, and will stay so even after multiple doubling a of production.
If SMRs are cheap enough to act as backup to wind and solar, they are cheap enough to displace wind and solar entirely. And the contrapositive as well: if SMRs are not cheap enough to displace solar and wind, they aren't cheap enough to act as backup. The scenario where it's just a backup never arises in cost minimized solutions.
> If SMRs are cheap enough to act as backup to wind and solar, they are cheap enough to displace wind and solar entirely.
That doesn't follow necessarily. Wind & solar being the most cost effective doesn't mean you remove all backups just because they aren't as cost effective.
Its the other way around. If you have sufficient nuclear to act as a backup, then you have sufficient that you do not need the wind and solar in addition.
My point still stands though given that I specifically did not exclude any scenario. It makes more sense to optimize when you include all energy sources. It's still possible some sources won't end up in the final solution and that's fine.
If taking that step, why charge the batteries with extremely expensive nuclear powered electricity rather than cheap renewables?
It is done when moving electricity around when the grid is strained. Buy expensive electricity and sell it at even higher prices. But that is a vanishly tiny portion of the demand.
What is needed is an alternative storage that minimizes capex, even if that means operating at lower round trip efficiency. Hydrogen or ultra low capex thermal storage.
Think 'agile', not 'waterfall'.