I own a diesel VW Golf, which I bought thinking it was a better choice for the environment than a gasoline engine. Therefore, I was disappointed to read your message that diesel is probably a worse choice. However, you didn’t talk at all about biodiesel. Can you give us a rundown on this fuel — how to get it, how it may be beneficial, and what you might have to do to ensure your car can run on it safely? Thank you.

Sputtering in Vermont
Burlington, Vt.

Dearest Sputtering,

Here at Grist Command Central, we received an overwhelming number of responses to my comments on diesel engine emissions; like yours, almost all of them pointed out my failure to mention biodiesel. So I return, once again, to the wonderful world of the combustion engine. For starters, everyone who hasn’t already done so should go read the article on the Ayotollah of Canola that ran in this magazine several weeks ago. If nothing else, the story will leave you with an idea of how incredibly cool it is to run your engine on biodiesel.

A decked-out biodiesel vehicle.
Photo: NREL.

Biodiesel is vegetable oil that has undergone a simple chemical process that yields a fuel compatible with diesel engines. Purchased in bulk or at the pump, or made at home, biodiesel is a lower-emission, somewhat-renewable fuel option for school buses, tractors, trucks, passenger cars, and perhaps your cigarette lighter.

Diesel engines run on compression ignition: An oily fuel mist is sprayed at very high pressure into compressed air, whereupon it explodes and drives the pistons. Any decent biodiesel booster will proudly mention that Rudolph Diesel initially designed his engine to run on peanut and other vegetable oils. Most modern diesel engines will still operate just fine with veggie fuel, so if you have one, you could try it today. Drive over to the nearest biodiesel pump, or better yet, get old fryer grease from your local Denny’s, refine it into fuel, pour it into your gas tank, and drive around town feeling punk as all get out.

This all sounded much too easy to me, so I called Dancing Rabbit Ecovillage in Missouri, where they have a fleet of two biodiesel vehicles. Don at Dancing Rabbit assured me that I hadn’t missed the fine print; with few exceptions, diesel cars can be pumped full of biodiesel without so much as a howdy-do. Biodiesel corrodes natural rubber, but you can easily replace the tubing in your vehicle with synthetic rubber. The main issue is biodiesel’s gel point; when the weather turns chilly, biodiesel begins to goo up the engine like a sinus infection. You’ll either need to revert to petrodiesel during the nine months of Vermont winter, or find some way to keep the fuel warm. The folks at Dancing Rabbit installed a fuel-heating tank in their Jetta, enabling them to run it all winter — in Missouri, no less.

Biodiesel engines get the same mileage as those fueled by conventional diesel — which is to say, a lot — while emitting less CO2, less sulfur, and less particulate matter. Translation: Biodiesel-fueled vehicles contribute less to climate change and cancer-causing air pollution. (Unfortunately, the nitrogen oxide emissions of biodiesel are comparable to petrodiesel, unless you modify the engine.)

The biodiesel bible.

In addition to the emissions differences, biodiesel is touted as a sustainably harvested fuel. As mentioned above, you can make it yourself from used restaurant grease, for eau-du-french-fry exhaust. When it’s manufactured commercially, biodiesel is made from oil-seed crops like soybeans, rapeseed, and palm oil, and industry reports talk of boosting national soy production to improve the farm economy. The sustainability argument starts to fall a little short right about here, as far as I’m concerned. Our current agricultural system ain’t sustainable, and the U.S. soybean crop gets more genetically modified with each passing year. Moreover, simply changing what we burn in the internal combustion engine will not magically solve all the problems posed by the passenger car.

That said, I wish I had a diesel car kicking around so I could convert it to a grease-mobile. Instead I’ll live vicariously; if you want to put a little biodiesel in your VW Golf, go to town! I’d recommend you start by checking out the biodiesel bible, From the Fryer to the Fuel Tank, by Joshua Tickell. Good luck, and happy trails.