To be fair 10 hours is either a pretty old or pretty massive unit. 2 hours might be a little more reflective of modern gas turbines. Especially combined cycles. But depending on how big the peak is, you need every available unit, both old and new.

Ultimately the issue is it’s very hard to meet that peak when all of your gas units have to go from 0 to 100% output. Much easier (and more reliable) to take them from 10% to 100%. Which is what grid operators do currently.

Yea an affordable battery in every home would be a slam dunk. This is kinda already happening with vehicle2grid (v2g) electric car protocols. But not everyone has an EV yet. And operators are still working out the kinks using this in the grid.

Plus the lithium batteries in cars have their own supply/recycling issues.