Treethanol - Production

Production

Cellulosic ethanol is produced using the lignocellulose biomass that comprises much of the mass of plants. Essentially at the core of the plant material we find cellulose, which can be broken down into simple carbohydrate sugars. After these sugars have been extracted, they can be then be fermented into an alcohol- and this alcohol is known as ethanol. The most widely used and promising means of creating cellulosic ethanol is called the cellulolysis process. This process consists of hydrolysis on pretreated lignocellulosic materials. Then enzymes are used to break down cellulose into glucose. This glucose is then fermented and lastly distilled. The pretreatment step mentioned above is necessary when processing cellulosic ethanol due to the fact that the glucose (sugars) are not readily accessible as they are with other ethanol sources such as corn or sugar cane. Rather, the cellulose in wood must be separated from the encapsulating hemicellulose and lignin. Further, there are three types of pretreatment: physical, chemical, and biological. As the name suggests, physical treatment involves physically reducing wood particle size. This can be accomplished through chipping, grinding, etc. Biological treatments involve the use of microorganisms to breakdown the wood. This type is considered favorable to physical pretreatments because it consumes far less energy in comparison, but the biological method has not proven to be scalable to an industrial level. Lastly, the chemical method utilizes an alkaline or otherwise acidic medium to make the cellulose within wood fibers more accessible. This has shown to be the most efficient and has the lowest energy cost.

Forest trees make up more than 90% of the total terrestrial biomass while performing functions such as carbon sequestration, producing oxygen, and promoting biodiversity. Trees are a promising source of ethanol because they grow all year round, require significantly less fertilizer and water and contain far more carbohydrates (the chemical precursors of ethanol) than food crops (like corn) do.