A 2005 USDA and DOE joint report [12] showed that a combination of crops, agri­cultural residues, trees, forest residues, and bringing conservation reserve land into production could generate up to 1.3 billion dry tons of biomass each year. Given
the assumptions regarding a viable conversion process, the energy inherent in this biomass could produce enough biofuels to replace 30-50% of the annual transporta­tion gasoline in US. Thus, biomass represents considerable potential as a feedstock for biofuels, which is reflected in the Renewable Fuel Standard (RFS) contained in the Energy Independence and Security Act of 2007 [18]. Specific targets are man­dated for lignocellulosic-derived ethanol in the RFS: the initial goal is 0.1 billion gallons by 2010, with increasing milestone targets that reach 16 billion gallons by 2020. The RFS also calls for 15 billion gallons of ethanol from grain, and the mandate then caps that volume from 2015 onwards [2]. Thus, corn and lignocel — lulosic ethanol plants will coexist and since there are common processes on the back-end, it is possible that integrated biorefineries (Fig. 2) may emerge to handle both starch and lignocellulosic feedstocks. The integration of cellulosic and tra­ditional dry grind ethanol plants may reduce the per gallon capital investment of lignocellulosic plants, will certainly smooth the risk of lignocellulosic ethanol, and may also improve ethanol yield on a per acre basis [19, 20].

Besides fuel ethanol or butanol, many other chemicals and value-added products may be produced from lignocellulosic biomass. Once the technologies for biore­fineries are established and commercialized, a wide range of chemicals (e. g. olefins, plastics, solvents, many chemical intermediates) and biofuels (e. g. biogasoline, alcohols, biodiesel, JP-8, and FT liquids) could be produced from lignocellulosic biomass.

Chemicals

Food products

Animal feed

Lignin residue

Heat & power

Fig. 2 Possible integration of different biorefineries