Biodiesel was probably the first of the alternative fuels to really become known to the public. The great advantage of biodiesel is that it can be used in existing vehicles with little or no adaptation necessary. Biodiesel is, naturally, a compromise for this reason, but still balances positively on the energy scales. There are energy plants available that will produce a higher yield in kWh per area, but the simplicity of having a fuel that is fully compatible with present fuel and engine technology makes it very attractive.Cars running on Bio Ethanol ,which is produced from agricultural crops, sugar cane or bio-mass, are governed by the same law of physics as those using gasoline. That means both emit CO2, as an inevitable consequence of the combustion process. But there is a crucial difference: burning ethanol, in effect, recycles the CO2 because it has already been removed from the atmosphere by photosynthesis during the natural growth process. In contrast, the use of gasoline or diesel injects into the atmosphere additional new quantities of CO2 which have lain fixed underground in oil deposits for millions of years.
