Gasohol generally refers to a mixed blend fuel containing 10% ethanol and 90% gasoline. Manufacturers create ethanol using a distillation process similar to the methods used for making drinking alcohol. Gasohol fuel has advantages that include decreased dependence on foreign oil. Its disadvantages include decreased fuel economy. The concept of alternative fuels originated in the 1970s when the United States was faced with a fuel shortage.
Consumers can determine the amount of ethanol in gasoline by finding the E number on the gas pump. E10 is gasohol, while E85 represents fuel containing 85% ethanol and 15% gasoline. Most modern vehicles accept gasohol without requiring engine or fuel system modifications. Manufacturers claim that vehicles made between 2001 and 2006 may use fuel mixtures containing up to 15% ethanol. Only mixed fuel vehicles run on fuel composed of more than 15% ethanol.
Distilleries make the ethanol from sugar or starch foodstuffs that are traditionally used to feed livestock. Though corn, Jerusalem artichokes, sorghum, and sugar cane might also be used in processing. Distilleries might use sugar beets or wheat as well. The quality of the crop does not affect the final product, allowing farmers the opportunity to sell inferior or spoiled produce. In order to reduce crop production costs, researchers developed ways of using grasses, paper, and wood to make methanol, which can also be a fuel component and burns like ethanol.
The first step in manufacturing gasohol is making the anhydrous ethanol, meaning ethanol with no water. The crop initially undergoes a mashing process, which releases the sugar or starch. Distillers ferment the mash using bacteria or yeast, which converts the sugars or starches into ethanol and carbon dioxide. Heating the fermented mixture to 178 degrees Fahrenheit (80 degrees Celsius) causes the ethanol to evaporate. It escapes the enclosed vat in the form of steam through tubing. Cooling the tubing, converts the steam back into a liquid.
The liquid now contains ethanol and water. Through further distillation, manufacturers produce a substance consisting of at least 95.6% alcohol. One part ethanol is mixed with nine parts gasoline, a product with an octane level two to four points higher than regular gasoline, which prevents engine knocks. Gasohol burns more efficiently and completely than gasoline, leaving behind fewer tail pipe emissions.
Though internal combustion engines can run on gasohol, the mixed fuel is not without dangers. Studies indicate that gasohol eventually corrodes the metal in engines and gas tanks and causes the plastic and rubber of the engine and fuel systems to deteriorate. Fuel injectors and fuel systems clog, and metal parts also develop varnish build-up.