Although in fairness liquid fuels are storable, so you can use intermittent solar and wind to run syngas processes. Low carbon power isn't really the hard part, grid stability and the existing vehicle fleet is.

Also of course, you could theoretically build nuke plants in the middle of nowhere that are remotely operatable, then use the power to make fuel. That could avoid NIMBY related costs.

I think low-carbon power is fairly well understood in the form of solar and wind, and in future, maybe wave. The big problem is we can't store it or meaningfully transport it over huge distances.