Is worth mentioning considerations of mixing any of the types with each other and standard diesel. The article on wikipedia is very good for bio diesel and well worth reading if you havent already.

Also practical considerations such as viscosity and freezing points are worth mentioning and how they can be over come *cough* white spirit.

Also the effects on engines and fuel lines, it will degrade some types of plastic usually on much older engines, it is also a better engine lubricant and when used for the first few times will clog the filter as the engine gets cleaned.

Mentioning a bit about the various crops would be good too, how difficult they are to grow what their yields are that sort of thing.

Hope this helps there is lots of information out there but lots of people are doing different things in different ways so is hard to find reliable data.

Best of luck

Also the effects on engines and fuel lines, it will degrade some types of plastic usually on much older engines, it is also a better engine lubricant and when used for the first few times will clog the filter as the engine gets cleaned.

This could be reduced by switching to high quality synthetic lubricating oil beforehand to clean things out and further reduce friction. Not to mention the 25000 mile oil changes or eliminating oil changes with a low micron bypass filter, and the associated reduction in oil use and disposal, increased engine life, etc.

"You get what you pay for. $4/gallon pays for an awful lot of terror."

An excellent, and very comprehensive book on biodiesel is "Biodiesel, Basics & Beyond" by William Kemp. He's Canadian and focuses on using used cooking oil to produce a highly refined, commercial grade biodiesel. He differentiates this high-quality product from other more "down and dirty" products produced on a small scale. He covers alot of issues relating to processing and reusing catalysts, by-products.

Great subject