Essay Biofuels

The increased emphasis on biofuels is due primarily to the increasing cost and demand for liquid fuels such as gasoline and diesel, and our desire to be less dependent on foreign oil. In addition to increased demand, the higher cost of petroleum may be related to the peak oil theory, discussed in the essay on petroleum and fossil fuels. According to this theory, the amount of petroleum in the earth is finite and at some point, the total amount of petroleum produced each year will begin to decrease. Many experts believe that we have either already reached the peak in oil production, or we will reach it within a few years. 

After fermentation, fractional distillation is used to separate the ethanol from the fermentation mixture. In Experiment 18, ethanol is separated from a fermentation mixture by fractional distillation. 

Another biofuel that is widely used in the United States is biodiesel. Biodiesel is produced from fats or oils in a base-catalyzed transesterification reaction  

Because the R groups may have different numbers of carbons and double bonds, biodiesel is a mixture of different molecules, all of which are methyl esters of fatty acids. Most of the R groups have 12-18 carbons arranged in straight chains. Any kind of vegetable oil can be used to make biodiesel, but the most common ones used are the oils from soybean, canola, and palm. In Experiment 27, biodiesel is made from coconut oil and other vegetable oils. 

Biodiesel has similar properties to the diesel fuel that is produced from petroleum, and it can be burned in any vehicle with a diesel engine or in furnaces that burn diesel fuel. It should be noted that vegetable oil can also be burned as a fuel, but because the viscosity of vegetable oil is somewhat greater than diesel fuel, engines must be modified in order to bum vegetable oil. 

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For additional information on the production of ethanol, see the essay Biofuels that precedes Experiment 27. In this essay, the production of ethanol from corn for use in automobiles is discussed, along with the production of ethanol from other sources such as plant cellulose. 

We have included a new essay "Biofuels." Substantial revisions were made to the "Petroleum and Fossil Fuels" essay and "The Chemistry of Sweeteners" essay. Other essays have been updated as well. 

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