[cogman10]

> We probably need new chemistries to get the seasonal storage potential of pumped hydro.

Yup. It might be possible to overbuild solar/wind to solve the problem (just need enough juice to offset the night). Won't be possible with current chemistries to have enough power to cover cloudy days or snow-covered solar panels.

> it seems while folks have been gnashing teeth on how expensive they are

This to me seems like a fixed perception based on outdated information. Batteries were quite expensive and required loads of rare earth/horrible chemicals to produce... 30 years ago when NiCd was fairly prominent. Now they are dirt cheap and due to get even cheaper with sodium ion coming to market. We are already manufacturing TWh of batteries yearly. Enough that we could theoretically have a full day backup everywhere in 10 to 20 years without any growth in manufacturing capacity.