Renewable ethanol is manufactured in a biorefinery by fermenting sugars into alcohol. In the EU, these sugars typically come from a variety of agricultural sources such as wheat, corn, barley, rye, triticale, and sugar beet. While the feedstock used typically varies depending on market conditions, the majority of renewable ethanol biorefineries are built to specifically process either grains or sugar beets. Currently, the most commonly used feedstocks in Europe are corn, sugar beet and wheat.
The ethanol production process includes several steps, of which the most important are:
The process can vary slightly depending on the feedstock used.
Advanced ethanol is produced by using agricultural residues such as straw, non-food ligno-cellulosic materials and waste.
The complex production process for ethanol made from cellulosic material, waste or residues requires breaking down the feedstock into fermentable sugars. To achieve this, innovative technologies in the form of enzymatic hydrolysis and pre-treatment are used. Once this process is completed, the remaining production steps are similar to those used to make ethanol from agricultural crops.
The feedstock for advanced ethanol is typically from the non-edible parts of crops such as straw, corn cobs and husks, and also dedicated energy crops. The biodegradable fraction of municipal solid waste is considered to be a promising feedstock.
Processing this feedstock requires high-tech facilities, pioneering enzyme and yeast extraction technologies as well as highly skilled people.
Ethanol made from cellulosic, waste or residue material has the same chemical characteristic as any other type of ethanol; when used as an alternative fuel, it is commonly known as second-generation ethanol.