--You are still oxidizing carbon when you burn a biofuel. I don't see how biofuels will alter the so-called carbon footprint. ALL the energy comes from the exothermic bonding of Carbon to Oxygen. --
When we burn fossil fuels, we are liberating carbon that has been locked up for eons. When we burn biofuel, we are liberating carbon that was just recently taken from the atmosphere. It's called recycling.
I see ethanol production actually putting more carbon into the atmosphere. Fosil fuel carbons will be used to form the new fuel. New and old carbon released instead of just the old.