Originally Posted by Vital

In its purest form, ethanol has approx. 25% less energy than gasoline, resulting in a fuel economy drop of 15-25% depending on the engine it is burned in. Aside from the energy content, the biggest difficulty with ethanol fuel is its higher octane rating. A higher octane rating allows for better ignition at high compression, in a full throttle situation for example. Engines that do not run at high compression ratios do not benefit from higher octane ratings and will generally run poorer regardless of the fuel type used (There are exceptions).

Chemically, vegetable oil has less energy than diesel fuel; this is noted by a lower cetane value. Consequently, engines running on the plant-produced fuel get approximately 10% poorer fuel economy than their fossil fuel counterparts. Change in the engine’s power production can also fluctuate by up to 10% due to the lower energy content. Regardless of source, vegetable oil/biodiesel is highly viscous. Unlike diesel made from petroleum, this reduces the fuel injector’s ability to atomize the incoming fuel. Less atomization can cause lubrication and deposition problems and ignition can be a problem too. In our Canadian climate (usually...) cold weather starting or operation could be a serious problem as the fuel begins to congeal below 50 degrees.

Pros and cons for each as far as usage is concerned, but each have similar source problems. If they cannot be produced by sustainable means, they offer little social benefit aside from minor pollution reduction (not always so for biodiesel). If we can afford to supplement gasoline or diesel with more "natural" products in a sustainable fashion, then I encourage policy change.

Just for fun... to give you an idea of how much we would have to devote to a wheat-based ethanol crop for the Canadian market (my numbers are now a year and a half old):

-For Canada, there is an exceptional amount of unused wheat available for export. Each year approximately 17 000 000 tonnes of wheat produce could be diverted for ethanol production
-Current Canadian technology is capable of producing 370 liters of ethanol per tonne of wheat, translating to a potential 6 290 000 000 liters of ethanol per year
-The most recent statistics indicate that Canadian gasoline consumption would require almost 6 times that amount of fuel.