Biodiesel engines are essentially standard diesel engines. In fact, the original diesel engine, designed by the 19th Century German engineeer and inventor Dr. Rudolph Diesel (after whom the engine is named), used vegetable material and coal dust as fuel. Most modern diesel engines can run off of biodiesel fuel without any modifications; allowing users to power their vehicles by using leftover vegetable oil from fast food fry vats. Early proponents of this fuel source proved the practicality of biodiesel by driving Volkswagen Rabbit Diesels across the country where they did their refueling at McDonalds restaurants along the way.

Biodiesel processors can be built by just about anyone enabling them to make biodiesel fuel at home. Basically, all you are doing is thinning the vegetable oil so that it will flow through the fuel lines. It is a process called transesterification - or alcohlysis - and involves the adding of ethyl alcohol to the vegetable oil. You can build a biodiesel processor at home for just a couple hundred dollars using an old water heater, a pump, some plumbing fittings and a plastic jug. There are numerous plans and schematics available online.