Bioethanol is a fuel made mainly from sugar plants (beetroot, sugar cane) or starch (cereals, maize). “Second-generation” or “advanced” bioethanol can be produced from non-food raw materials such as crop residues, agro-industrial waste and even wood.
Bioethanol is produced by fermentation of sugars and then by distillation. The fermentation stage transforms the simple sugars (such as those present in beet, sugar cane, etc.) into ethanol. The distillation makes it possible to separate the water from the ethanol in order to purify it.
In addition to bioethanol, factories producing bioethanol could produce other products that can be used for food and feed, green chemistry, etc. We are talking about a biorefinery.
In the case of the use of agricultural residues (straw) or other lignocellulosic materials, two additional steps are necessary. In fact, these raw materials contain “complex” sugars that must be released (fibers need to be broken) and then transformed into simple sugars (hydrolysis) before carrying out the fermentation. This “second generation” biofuel production is still under development, although some industrial-scale production units exist already in Finland, for instance.
More than fuel for cars
Bioethanol is mainly used as a fuel for vehicles but can also be used in the chemical industry (platform molecule, biosolvents, etc.) or as fuel for the production of heat and/or electricity.
Mixed with petrol, bioethanol can be used in various proportions in road vehicles. Since 2013, gasoline sold at the pump contains approximately 6% volume bioethanol without engine modifications.