Ah, where do I begin talking about the merits of biodiesel. How many fuels do you know that you could safely drink? How many fuels produce a pleasant smelling exhaust (fries anyone)? How many fuels are 10 times less toxic than table salt and biodegrade as fast as sugar? Biodiesel not only has these non-toxic properties, but also produces nenergyearly as much power as petrodiesel (only 3 -5% less). It also delivers over 3 times as much as it takes to produce it (compared to 0.66 times for hydrogen).

Quick Overview:

Diesel engines were originally intended to run on peanut oil, and Rudolf Diesel demonstrated this at the Paris World Exposition in 1900. Unfortunately, after his death in 1913, the rise of the petroleum industry lead to the redesign of diesel engines to run onlyl on petroleum based diesel. Diesel engines can use vegetable oils as fuel, but the engine design requires that the oils first be made thinner- i.e. less viscous. This thinning can be done either by heating the oil first, or by chemically treating it in order to remove the thicker part (glycerin) which gets discarded, a process known as transesterification. There are a lot of people using waste vegetable oil conversion kits in order to run their cars on pure vegetable oil. This is a great option if you want to spend the money and energy up front to install the system, and are set up to rigorously filter the waste oil or be willing to spend the extra money for virgin oil (see: Journey to Forever website's SVO section). The beauty of biodiesel is that you don't have to do anything to your car; as long as the car has a diesel engine, you can just fill 'er up and go. There are some caveats to this; if your car was made before about 1992, you may want to replace rubber hoses and seals, as biodiesel tends to dissolve rubber a bit. Also, it's important to get or make quality fuel, but I'll get into that later. For a nice treatise on many aspects of biodiesel, go to Wiki pedia's biodiesel section:
Note Wiki's especially good explanation of the chemistry of the reaction.

What is Biodiesel?

Benefits of Biodiesel!