I was thinking about this last night. CO2 is one of the prime concerns in global warming, its one of the things that man produces in abundance. In using biofuels, that is plant based fuels, would we not be helping that problem at the same time? Consider this, plants typically produce their energy by consuming CO2 and H20, with O2 as the byproduct. We burn that fuel using O2 to produce CO2 and H2O as the byproducts. Obviously the equation isn't balanced and we produce far more CO2 than plants consume, but by using plants to produce our fuel aren't we perhaps drastically reducing the amount of excess CO2 produced every year?