That’s a good point, the promise of a sunlight -> biofuel conversion process is indeed interesting, but I don’t know if it’s efficient enough yet to really begin betting on.

Engines don’t have that problem. Once an engine uses the fuel it throws it away. The engine can fully run the reaction without having to put up limiters to keep it in bounds. If the battery ran the reaction as completely as our engines do. . .you have to throw it away.

So really the question is whats the most powerful chemical reaction that is readily reversible. There really aren’t that many that can produce an electric current overall and there are even fewer that can produce a current and be reversible.

Without the development of some other chemical reaction that is readily reversible, batteries and fuel cells are out of reach for vehicles. Having come from a minor in chemistry I’m pretty confident that most of those reactions are already catalogued. Chemists have been using electricity(as a byproduct in reactions and to cause them) for alot longer than just about anyone else.

The development of designer life forms that convert CO2 en masse to to gasoline(or any of the other hydrocarbons) looks to be the answer and Honda is predicting it. If you have plants that consume CO2 and sunlight to create gasoline alternative fuels become caviar and Honda doesn’t want to get stuck holding the dead fish.