.renewables are going to have their work cut out for themselves just supplying a majority percentage of the power for national electricty grids. I'm not sure where they think the extra renewable power to do this will come from.
No, the biggest problem with wind in particular is that to get reasonable amounts of energy you have to install large overcapacity.
Which leads to the problem of what you do with that energy on a windy day.
Up till now Germany has been selling it to (among others) France, for almost nothing. This is bad for Germany (they get very little money) and bad for France (it makes the nuclear fleet less profitable).
Making synthetic fuel when you have energy to spare could be a pretty smart storage mechanism.
Wonder what the efficiency is like though.