> This tempers high-frequency variation. The 2% over a full year lower-frequency variation is the problem.

Right. And that's where the e-fuels come in. Using batteries for that storage problem is absurd and unnecessary. The argument that renewables can't reach 100% because batteries can't do year-scale leveling is a strawman argument. It's bad engineering to try to use batteries for that use case. And because 2% (say) is such a small fraction of the total demand the low round trip efficiency of using e-fuels for grid storage doesn't hurt much overall.