Biomass Processing in the Twenty-First Century

In order to be cost-competitive and to contribute significantly to expanding the sustainable resource base for modern society, technology for processing cellulosic biomass must be rapid, highly-efficient, involve few process steps, utilize all plant components, and be based on sustainably-produced feedstocks. The potential to achieve these goals will be considered. Recent work (Lynd et al., 1996)will be reviewed that projects the cost and features of mature technology for producing ethanol from cellulosic biomass. A new point developed in this paper is that the technical advances anticipated for mature ethanol technology are equally applicable and enabling for a very wide variety of products derived from cellulosic biomass. for biomass processing featuring fermentation, utilization ofall plant components requires that multiple products be produced. In particular, coproducts need to be produced from lignin (in the case of woody plants), and protein (in the case of herbaceous plants). We consider here advanced processes for producing ethanol in conjunction with either electricity or feed protein, and examine the likely features of such processes in terms of thermodynamicefficiency, land requirements, greenhouse gas emissions, and economics.