Often I'm asked why I'm a proponent of vegetable oil as a fuel, rather than a fuel that doesn't emit CO2, such as Hydrogen. Carbon neutrality is more important than to zero CO2 emissions at the tail pipe. Hydrogen is no more a fuel than are the batteries of an electric car- you put energy (electricity) in to make it, and it's then just a carrier of that energy for a vehicle. If the Hydrogen was produced using electricity from a nuclear power plant or coal plant, you still contributed new CO2 to the atmosphere. Using plant mass as a fuel, however, is carbon neutral. When plants grow they convert CO2 to oxygen- the same amount that will be turned back into CO2 when it is used by cars. Thus, you could accurately say that a veggie car is, in some cases, less of a CO2 contributor than a Hydrogen car. The promise Hydrogen offers is that of a better fueling infrastructure: one that will centralize energy conversion (and thus any CO2 production) to one location and source.