Solar, wind, hydro, fission and fusion are all different, with different strengths and weaknesses. Building capacity for one source (making it cheaper in the process!) does not go to waste. Power plants will continue to operate continuously to recoup their capital cost.
A renewable-only grid is generally not the consensus view, just something Greenpeace pushes
https://www.lazard.com/research-insights/levelized-cost-of-e...
Olkiluoto 3, Finlands newest nuclear reactor sells electricity for 40€/MWh. Even if you double that, to account for the French subsidy, you only end up at $86/MWh after currency conversion.
The same Lazard research report also states that: "Combustion turbines for 100% hydrogen are not commercially available today".
Given that you have to produce something other than hydrogen to produce clean energy this drives down efficiency further.
So, what are these completely insane things that you can do with renewable energy sources and still come out ahead?
> The same Lazard research report also states that: "Combustion turbines for 100% hydrogen are not commercially available today".
50% hydrogen already in use:
https://hydrogen-central.com/ge-new-gas-turbine-help-smooth-...
A DOE grant to get to 100% hydrogen:
https://www.ge.com/news/press-releases/ge-doe-accelerating-t...
No need to let perfect be the enemy of good. Make synthetic methane to get the hydrogen blend needed.