ABSTRACT
Ethanol is one of the simplest alcohols that have long been consumed in human history. Ethanol can be readily produced by fermentation of simple sugars that are obtained from sugar crops or converted from starch crops. This has long been practiced throughout the world. Feedstock for such fermentation ethanol includes corn, barley, rice, and wheat. This type of ethanol may be called grain ethanol, whereas ethanol produced from cellulosic biomass such as trees and grasses is called cellulosic ethanol or biomass ethanol. Both grain ethanol and cellulosic ethanol are produced via biochemical processes, whereas chemical ethanol is synthesized by chemical synthesis routes that do not involve any fermentation step.
