Biodiesel is available commercially at some locations around the country, or you can make it yourself. It is made from a chemical reaction by which the glycerine is removed from vegetable oil, leaving the methyl or ethyl esters, depending on the catalyst used. Some people make it themselves with a high success rate. I have a 55 gallon drum delivered to my house and fuel-up here.
There are many online resources regarding buying, making, and using biodiesel.
www.biodieselnow.com, http://biodiesel.infopop.cc, www.vegenergy.com are a few. Mercedes 617 engines are very happy with it; mine actually seems quieter, and I run it at 100% strength (b100)
Biodiesel is superior in emissions in most categories, though NOx emissions are higher. However, with no sulpher, you can add a catalytic converter if you care. I'm working on a two port exhaust design so I can run regular petro-diesel and bio-diesel or just straight vegetable oil and get the emissions as clean as can be.
I bought the diesel for the environmental interest- wanted to run it on regular old vegetable oil. And, I will- probably next year. For now, I'm making sure the car is fully reliable on fuel that requires no modification of the fuel system.
Biodiesel costs more than petrodiesel if you buy it at a pump. It is not just supply and demand... Diesel fuel is subsidised to make the trucking industry work. However, because biodiesel is the product of a plant- usually soybeans- it can actually be grown domestically. So, no matter what you think of the war in Iraq, you could rule out war for oil. If you make your own biodiesel, and you collect vegetable oil that restaurants are disposing of anyway... it can be pretty cheap. methanol or ethanol and lye are the most common catalysts, and become your primary expense.
Eventually, I'll have a second, heated fuel tank/line with a separate fuel filter and water separator that will handle the vegetable oil I get from a restaurant and filter. Free fuel, with no discernable difference in performance, and a major environmental emissions reduction. Works for me!
Straight Vegetable Oil kits are available at
www.greasel.com, www.greasecar.com, and
http://www.biofuels.ca (my choice) but Dana Linscott- a member here- has a site as well with inexpensive directions on making your own kit for veggie oil.
Since I'm in GA, I'm not too concerned about winter, but some others find that soy based biodiesel tends to cloud and gel at higher temps than dinodiesel, and that some anti-gel agents do not work. We'll see!
We've got a fledgling group together here in atlanta that meets once in a while to conduct biodiesel business...
www.vegenergy.com is run by Rob DelBueno, who can talk biodiesel all day long. Apparently, so can I. Holy crap.
Cheers,
Kevin