Yes, it is very common!

A diesel motor is a very versatile device. It can burn many fuels - almost anything really - as long as it is injected as a warm atomized fluid and contains hydrocarbons. You can run diesel motors on the gasses released from compressing wood chips or human excriment. Its all a matter of delivery.

There are really two ways to run bio fuel:

1. Run "Bio-Diesel". This is a fuel created from vegetable oil. It is heavily refined and uses some house hold chemicals. You can brew it yourself in a 55 gal drum in your garage if you choose. Total cost comes to about $0.60 per gallon, assuming the veg oil is free. And the best part ... you can run it on a 100% stock diesel motor. No modifications to anything neccesary. Just pour it in and go.

2. Run "Greasil". Greasil is raw waste vegetable oil. You can get it from greasy joints around town. Sadly, you need to do some modifying to run it in a diesel motor. You need to install a second fuel tank, one for the grease and one for diesel, because you need to start your motor on diesel, then switch over to the grease once the motor gets hot. This requires valves and line running. You also need to install filters for the grease. And finally, you need to install a heater to heat the grease fuel, so it can flow through the lines as a liguid (grease becomes solid at low temp). Total investment, if done yourself, is between $250 and $600.

Personally, I would brew the biodiesel. It is easier and ultimatly, a better fuel.

Whatever you decide, you should pick up the book ""Vegetable Fuels".