The place where I purchase fuel from in the bay area only uses biodiesel made Waste Vegetable Oil
http://biofueloasis.com/

Also you might want to check out this video: http://www.mofilms.org/
As 300sdToronto said there should be a lot of focus put into where you are getting your fuel from. For example, clear cutting rainforest to grow palm to produce palm oil to make biodiesel is not in my opinion a good way to save the environment.