The choice of biomass feedstock is a critical driver in determining key performance metrics of bioenergy — including economic viability, scale of production (both at individual facilities and in aggregate), and environmental impact. For commodities such as fuels or electricity, feedstock cost typically represents two-thirds of the product cost, or more [26]; therefore, selecting a cost-effective feedstock is essential. As is discussed in Part IV of this book, the logistics of growing, harvesting, storing, and transporting biomass — unique for a given feedstock type — affects the feasible size of the processing facility, which, in turn, impacts the overall sector scale. Each feedstock also has a particular set of environmental attributes — for example, water use, wildlife habitat, soil quality, and so on — that significantly affects the environmental performance of the bioenergy system.

In assessing the suitability of a biomass feedstock for a given conversion process, several material properties are important to consider, including: (1) moisture content; (2) energy density; (3) fixed carbon/volatile matter ratio; (4) ash content; (5) alkali metal content; and (6) carbohydrate/lignin ratio. The first five properties are especially important in thermochemical processing. For biological conversion, the first and last properties are of primary concern.