[pfdietz]

I like playing with the modeling tool at

https://model.energy/

It lets you play with combinations of solar, wind, batteries, and hydrogen storage, and optimize for a minimum cost system that can provide "synthetic baseload" for an entire year for a region given high cadence historical climate data.

When I apply that to the US, for example, the storage needed is typically maybe 6 hours of batteries and a week or so of hydrogen. To put that last number in perspective: there is a salt formation in Delta, Utah that could supply enough hydrogen storage capacity to power the entire US for 30 hours.