Joe Thompson from University of Idaho at Moscow explains how to determine proper mixture of reactants needed to produce biodiesel.
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Running engine on home-made biodiesel.
Biodiesel is typically made from used vegetable oil (waste frying grease) collected from restaurants, although other options are available, like using vegetable oil that is off specifications and cannot be sold as food-grade. Other ingredients are an alcohol - typically methanol, but ethanol can be used also - and sodium or potassium hydroxide (lye). Methanol is sold in many rural areas as racing fuel, and sodium lye is sold in hardwre stores as a drain cleaner. The process of making biodiesel involves mixing alcohol and hydroxide in the proper ratio, which depends on the composition of the vegetable oil used, to create an extremely reactive mixture - sodium methoxide if sodium hydroxide and methanol are used. This mixture is then mixed with the vegetable oil. A reaction called trans-esterification then happens, which converts fatty acids (tri-glycerides) into methyl-esters (or ethyl-esters if ethanol is used) of fatty acids. The reaction yields biodiesel (esters of fatty acids - for example, soy methyl ester if methanol and soybean oil are used), glycerine, and a mixture of miscellaneous compounds that have no practical use and must be disposed of. Many people claim that they can get cheap fuel this way - cheaper than petroleum diesel or commercially made biodiesel. The downside is that when producing fuel on a small scale, it is difficult to maintain the quality of fuel, and often, contaminants are dissolved in the fuel, and cause clogging or coking of the injectors or premature wear on the injection pump. Also, while biodiesel is a safe fuel, making biodiesel involves handling some extremely flammable, explosive, reactive, and hazardous mixtures.
For more information on making your own biodiesel:
Other options: Commercially produced biodiesel
or Running on straight vegetable oil
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