A 1.1. What is fuel ethanol?
Ethanol is synonym with ethyl alcohol. Both terms refer to a type of alcohol consisting of two carbon atoms, five hydrogen atoms, and one hydroxyl group. As opposed to gasoline, ethanol is a pure substance consisting of only one type of molecule: C2H5OH. In ethanol production, however, it is necessary to distinguish anhydrous ethanol (or anhydrous ethyl alcohol) and hydrous ethanol (or hydrous ethyl alcohol). The difference lies in the water content of the ethanol grade: while the water content of anhydrous ethanol is approximately 0.5 percent by volume the hydrous ethanol that is sold at fuel stations has a water close to 5 percent by volume.(although the Brazilian specification defines this parameter by mass the information is presented on a volume basis for harmonization with international standards). In the industrial production of ethanol, the hydrous grade is the one that comes directly from the distillation tower. Producing anhydrous ethanol requires an additional processing sta
