This reminds me quite a bit of Green Freedom, a program out of Los Alamos which created gasoline out of atmospheric CO2 and H2O with some catalysts and an external energy source (they used nuclear). If I recall correctly, the gas would have cost around $4 a gallon, making it not quite competitive with gas where I live in Denver assuming you don't count for the externalities. When I get to work, if I remember I'll see if I can find a link and post it.