Weird Science

In the film "Back to the Future," Doc popped the hood of his time-traveling DeLorean and tossed kitchen scraps and beer cans into his gigawatt fusion converter thingamajig. It functioned much like a food processor/trash compactor, but converting waste into automotive fuel. Turns out that this cinematic solution to contemporary problems of both excess litter and fuel shortages isn't that far off the mark.


Petroleum-based fuels have always been a politically charged issue, especially now with Middle East turmoil and gas prices topping $2 a gallon in the U.S. There's a lot of information available on alternative sources of energy, but perhaps the most interesting, and weirdest, is the conversion of turkey parts, used restaurant grease and pig manure into usable fuel. Like the futuristic DeLorean, these fuel sources might solve multiple problems.

Biodiesel
Biodiesel isn't a new concept. The Massachusetts Port Authority runs biodiesel in its Logan Airport shuttle buses and the USDA's Agricultural Research Center is heated with it. Made from soybeans or waste cooking oil, biodiesel can be used straight or mixed with petroleum-based diesel fuel, and emits a distinctive French fry odor rather than the traditional diesel odor. Bus conversion includes the simple and fairly inexpensive addition of a catalytic converter to the exhaust system, but costs roughly one and a half times the cost of petroleum-based diesel.


The use of plants with higher oil content than soybeans or waste cooking oils would bring that cost down. A pair of Gustavus Adolphus College grads took the biodiesel theory literally. Last year, Aaron Crowell and Phil Graeve converted a 1981 VW Rabbit diesel pickup, named the Crisco Kid, to run on used restaurant grease with plans to take the Kid on a postgraduate road trip.


The conversion cost $250, and the Kid gets about 35 mpg, the same as diesel. The pickup starts on regular diesel fuel. Once the radiator heats up, warming the oil, the driver flips a switch to change the fuel source to its grease tank. Canola oil, one of the most common commercial deep fat fryer oils, is chemically similar to diesel fuel in the energy produced and burning characteristics, but it's more viscous and has to be heated before it runs through an engine.