What straightforward process do we have for making synthetic fuels with electricity?

My understanding is that synthetic fuels tend to be some form of hydrocarbon, which means they need a source of carbon. Either you make the synthetic fuel at the exhaust stack of a fossil fuel plant (so you still have to burn fossil fuels) or you spend huge amounts of energy collecting CO2 from the air (is that even a proven process yet?)

Hydrogen has a straightforward and well understood process to make it from water. What's the hydrocarbon equivalent?

Is there a better way to make synthetic fuels?