[Tcepsa]

That would violate the conservation of energy. Put simply: The energy that is released from those CH3 complexes has to be put back into them to make them be CH3 complexes again. Otherwise you could, for example, heat your house by burning the same bit of fuel over and over again (using some of the energy released by the combustion to recapture the carbon and rebind it to the hydrogen molecules and leaving the rest as heat to enjoy all through the winter). Alternately, you could generate a tremendous amount of electricity by the same method.

Sadly, thermodynamics says, "No."

[elcritch]

Ah my mistake. I misread and was thinking in regards to just doing the CO2 capture portion of generating fuel. Yes making new fuel from captured CO2 will take as much or more energy than released from burning it.

[Tcepsa]

Oh, yes that makes more sense (I don't know whether it's correct or not, but it is far more plausible!)