The increasing demand of fuel for transportation, increased world-demand for oil (gasoline), and the negative consequences of global warming have all contributed to the increased use of corn-based sugar to produce ethanol. Ethanol is blended with gasoline and burned in many of today’s passenger cars and trucks. Most gas stations currently use 10% ethanol in their gasoline. However, it has also been used as 85% ethanol to 15% gasoline at some gas pumps called, “E85” or flex fuel. Running this fuel in the gasoline motor typically does not require any mechanical modification. Not all gasoline motors are manufactured to run on E85, so it is best to check the vehicle owner’s manual before fueling up with E85.
Commercial production of fuel ethanol involves breaking down the starch present in corn into simple sugars like glucose and feeding these sugars to yeast for fermentation. Next, they recover ethanol, and other byproducts, such as animal feed, corn oil, and carbon dioxide. Ethanol is an alcohol produced by yeast during fermentation. Fuel ethanol is ethanol that has been highly concentrated and blended with gasoline to render the alcohol undrinkable.
For each pound of simple sugars, yeast can produce approximately 0.5 pounds (0.15 gallons) of ethanol and an equivalent amount of carbon dioxide. Corn is used for ethanol production because of its large volume of carbohydrates, specifically starch. Starch can be easily processed to break down into simple sugars, and fed to yeast to produce ethanol. Modern ethanol production can produce approximately 2.8 gallons to 3 gallons of fuel ethanol for every bushel of corn.
About 40% of the United States’ corn crop is used to produce ethanol. Ethanol production uses only the starch portion of the corn, which is about 70% of the kernel. All the remaining nutrients: protein, fat, minerals, and vitamins, are concentrated into distillers grains, and are used as feed for livestock. Some ethanol plants also remove the corn oil from distillers grains to create renewable diesel.