[IMG]http://simplefeed.consumerreports.org/rsrc/i/1/_/greasing_our_wheels_making_a_diesel_run_on_cooki_1 50323393/4.gif?f=3dcb3160-01dc-11dc-32a2-0019bbc55f7f&s=AewyNia7NTvDvhaDemju5DEsbnVsbCwwLDA *[/IMG] Greasing our wheels: Making a diesel run on cooking oil, diesel vs. biodiesel vs. vegetable oil
Diesel vs. biodiesel vs. vegetable oil We test homegrown fuel alternatives to gasolineWith gasoline prices high and the United States' addiction to oil becoming an increasing burden, consumers are taking more interest in alternative fuels, including those derived from farm crops and other renewable organic sources. These include biodiesel and even pure vegetable oil, both of which can be used to power a diesel engine.Developed from vegetable or animal fats, biodiesel produces no toxic byproducts and is functionally identical to petroleum diesel. Adherents claim it pollutes much less than regular diesel. Biodiesel is most commonly sold in blends with normal diesel. B5, which is 5 percent biodiesel and 95-percent petroleum diesel, sold for 10 cents less per gallon than regular diesel on nationwide average, according to the U.S. Department of Energy, February 2006. Pure biodiesel (B100) was cited as being 67 cents more per gallon than regular diesel in the same study. Biodiesel's price could come down as the market for it grows.A relative of biodiesel is plain, edible cooking oil. But because it's not financially practical to fuel a car with cooking oil from grocery store shelves--since a gallon costs about $9--some people are modifying diesel engines to run on the used deep-fryer oil that restaurants often throw away. Discarded oil is often available free or for little cost.To see how biodiesel--both B5 and B100--and fryer grease compare with conventional petroleum diesel fuel, we converted a diesel-powered 2002 Volkswagen Jetta TDI so that it could operate on all three. We found that they all allowed the car to perform well but differed in price and convenience. We experienced the best overall results using B5, the 5 percent biodiesel blend. It provided the best balance of performance, emissions, fuel economy, and convenience. B5 will run in any diesel engine without making vehicle modifications, and it is pumped into the tank just like any standard fuel. Because it is 95 percent petroleum diesel, however, it does little to wean drivers off fossil fuels.The Jetta also ran well on the used cooking oil, but the inconvenience of locating fuel sources and preparing the oil for use in the engine limits its appeal and offsets its very low price.The recipe for using cooking oilUnlike biodiesel, running a car on vegetable oil isn't as simple as just pumping Mazola into your fuel tank. First, cooking oil usually contains 20 to 30 percent glycerol, the key ingredient in bath soap, which makes the oil thicken or solidify at cool temperatures. In this goopy state, it can permanently clog fuel lines, pumps, and injectors. To avoid this condition, it's necessary to modify the engine so it can be started on conventional diesel or biodiesel and then warm the vegetable oil. Once the oil is hot and flowing easily, the presence of glycerol isn't a problem.A few miles before shutting down, you must also switch back to diesel to flush out the vegetable oil from the fuel-delivery system. Cooking-oil conversion kits are available from a number of small companies.When running on used cooking oil, you must also filter it to remove contaminants. Subscribe now!
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