Evaluating Physical, Chemical, and Energetic Properties of Perennial Grasses as Biofuels

The suitability of energy crops for either energy conversion into fuels or energy release through combustion can be measured by several indices that reflect energy content, density, and ease of recovery. These properties ultimately determine both the suitability and diversity of potential end uses of feedstocks and their potential value as agroindustiral resources. Our analyses indicate thatswitchgrass should be a versatile bioenergy feedstock. Energy content of switchgrass is comparable to that of wood with significantly lower initial moisture content. Early analyses of ethanol recovery from enzymatic hydrolysis by the National Renewable Energy Laboratory (NREL), indicate that switchgrass is very suitable substrate and produces high ethanol yield using current simultaneoussaccharification and fermentation (SSF) technology. Contrary to earlier reports, more extensive analysis of ash and alkali content of switchgrass indicates that it typically has a relatively low alkali content and should have low slagging potential in coal-fired combustion systems. As an agrofiber source for pulping, switchgrass has a relatively high cellulose content, low ash content, and goodfiber length to width ratios. It appears to be a promising substitute for hardwoods in the production of high quality paper. Harvesting and handling strategies can improve switchgrass suitability for industrial endpoints.