Biodiesel Fuel
by Oliver St John
This increasingly popular fuel can replace diesel in most diesel-equipped vehicles, and its emissions are not harmful to the Earth's atmosphere. A number of people incorrectly apply the term "biodiesel" to unrefined vegetable oils, though "true" biodiesel is a processed fuel, derived from the transesterification of animal fats and vegetable oils.
Currently, true biodiesel is more expensive to purchase than petrodiesel (standard diesel fuel), though the rising cost of petroleum-based fuels is narrowing this gap. The advantage, however, is that biodiesel can be made at home for a very minor cost.
In practice, many biodiesel converts are not using true biodiesel, but are deriving their fuel from waste vegetable oil, typically from restaurants or snack-food factories. However, the unmodified oil is not without its problems; the residue from burning the heavier parts of the oil has been known to clog the ports of fuel injectors in the diesel engine. The unmodified oil is also a poor lubricant by comparison to other fuels and may therefore wear out the injection pump more quickly.
This is not to say that waste vegetable oil is not worth the time - it can be converted to biodiesel at home by building a biodiesel processor, and biodiesel is in fact less apt to cause damage to the fuel injectors and may even help to remove clogs left behind by the burning of petrodiesel.
Jack Johnson, Guster, Dave Matthews and a number of other noteworthy musicians have converted their touring vehicles to run on biodiesel.
A guide on how to convert waste vegetable oil to biodiesel is available here
A noted issue with pure biodiesel is that its gelling point is around 40 degrees Fahrenheit (4 degrees Celsius), and therefore causes difficulties in the winter months. This is frequently worked around using a blend of biodiesel with low-sulfur petrodiesel and/or kerosene.
If you intend to use biodiesel fuel, and especially if you wish to use pure biodiesel rather than easing in via a biodiesel/petrodiesel blend, you may wish to consider replacing the rubber gaskets and hoses with ones made from a fluorocarbon rubber (often marketed under the trade name Viton), which is unreactive to biodiesel. It is also recommended, because biodiesel frequently cleans out residual deposits in the fuel lines of petrodiesel-based vehicles, that you change the fuel filter after the first 500-750 miles (800-1000 kilometers) of driving with either blended or pure biodiesel.