Definitions

Biodiesel

Biodiesel is an alternative renewable fuel derived from the deesterification and methylation of soy or rapeseed vegetable oil.

Cellulose

Cellulose is a linear beta 1-> 4 linked anhydro polymer of glucose. It is the principal component of all higher plant cell walls. In nature cellulose exists in crystalline and amorphous states. The thermodynamic stability of the anhydro beta 1 -> 4 linkage and the capacity of cellulose to form internal hydrogen bonds gives it great structural strength. Cellulose is degraded to glucose through hydrolytic cleavage of the glycosidic bond.

Hemicellulose

Hemicellulose is a term used to refer to a wide variety of heteropolysaccharides found in association with cellulose and lignin in both woody and herbaceous plant species. The sugar composition varies with the plant species, but in angiosperms, the principal hemicellulosic sugar is xylose. Like cellulose, xylose occurs in the beta 1-> 4 linked backbone of the polymer. In gymnosperms, the principal component sugar is mannose. Arabinose is found as a side branch in some hemicelluloses.

Lignin

Lignin is a polymer of three closely-related phenylpropane moieties. Unlike cellulose and hemicellulose, lignin cannot be depolymerized by hydrolysis. Cleavage of the principal bonds in lignin require oxidation.

Lignocellulose

Lignocellulose is the term used to refer to the bulk of plant material. It consists principally of lignin, cellulose, hemicellulose and extractives. Woody biomass is about 45-50% cellulose, 20-25% hemicellulose and 20-25% lignin. Herbaceous materials have lower cellulose, lower lignin and higher hemicellulose contents.

Starch

Starch is a polymer of glucose with alpha 1-> 4 and alpha 1-> 6 side branches. It does not have the structural or thermodynamic stability of cellulose and is generally used by the plant as an energy storage polymer.