Suitability of Perennial Grasses for Energy and Nonenergy Products

Perennial grasses are herbaceous, lignocellulosic plants. Their chemical composition is made up primarily of structural polysaccharides, namely, celluloses and hemicelluloses, of lignin, and of small fractions of nonstructural components, such as extractives, protein, lipids, pectin, and ash. The recalcitrance of lignocellulosic material has been recognized as one of the most important sustainability characteristics of this plant type, since it contributes to natural resistance to pests and diseases. However, the recalcitrance of the plant cell wall constrains the hydrolysis of structural carbohydrates for biochemical conversions, namely, second-generation bioethanol and anaerobic digestion. On the other hand, perennial grasses are suitable for thermochemical conversions; however, ash melting temperatures should be carefully evaluated for high-temperature processes. This chapter describes the suitability of lignocellulosic perennial grasses to thermochemical and biochemical processes for energy application and other alternative uses toward the biobased economy in Europe. The main chemical composition and factors affecting perennial grass biomass quality are discussed, and examples of the most widely used bioconversion processes involving perennial grasses are reported