It is a very old tech, basically, you make syngas ( mix of CO and H2 ) by electrolysing pressurized (~6bar) carbonated water at high temp (~200°C), then do a catalytic synthesis of liquid carbonhydrates from syngas. You could even combine electrolysis and synthesis in one-shot process adding catalyst to electrolysis step. You could make methanol, ethanol or other flammable things depending on catalyst, CO:H2 ratio and synthesis conditions you use.

The problem is that you need a lot of electricity and relatively complex device for that process. It is much easier to get syngas directly from fossil fuels or even wood (woodgas from gas generator), bypassing needless and highly ineffective conversion of fuel into electricity and then electricity into fuel. Then, do with syngas whatever you want - fuel ICE directly with syngas or synthesize liquid fuel for later use in ICE.

All in all it is very energy hungry process that is affordable only if you somehow have a lot of electricity. And by "a lot of" I mean really a lot needed to produce some decent amount of fuel enough for regular rides, not what you could harvest from even an acre of solar panels.