The combustion of methanol produce less C02 than natural gas.

The idea here is that methanol would be stored for times the renewable grid wasn’t producing enough electricity.

How often would that happen? It would vary a lot depending on other factors. Australia has enough sun to never need an option like this. How often would Germany use it? Depends again. How much other grid storage options might they have - pumped hydro, lithium batteries, etc, etc