S7: Integrated supply chain, delivered costs and life cycle assessment of several lignocellulosic supply systems for biofuels, bioenergy and bioproducts in the Southern U.S

Recent research and unsuccessful commercial facilities have identified high feedstock and conversion costs as major barriers of second generation biofuels commercialization. Consistent assumptions and system boundaries were used to determine delivered cost and environmental burdens resulting from the production of six regionally important biomass feedstocks including loblolly pine, eucalyptus, unmanaged hardwoods, forest residues, switchgrass and sweet sorghum. Total environmental burdens were quantified on a cradle-to-gate basis for nine mid-point indicators using SimaPro 7.2 software and the Tool for the Reduction and Assessment of Chemical and Other Impacts (TRACI) method.

Production of forest-based feedstocks resulted in lower delivered cost ($53.40 to $69.30 dry tonne ^-1) and lower greenhouse gas (GHG) emissions (-1,794 to -1,769 kg CO₂ eq. dry tonne ^-1) than agricultural feedstocks ($69.80 to $82.00 and -1,574 to -1469 kg CO₂ dry tonne ^-1). Forest residues had the lowest environmental impact and delivered cost. Conversion of cropland to intensively managed forest resulted in large reductions in GHG emissions (-547,360 kg CO₂ eq. hectare ^-1 over 100 years) due to carbon sequestration associated with direct land use change. Converting forests to agricultural energy crops resulted in a large increase in GHG emissions (469,809 kg CO₂ eq. hectare ^-1 over 100 years).

Using forest based biomass feedstocks instead of agricultural biomass feedstocks could reduce cradle-to-grave environmental burdens for biofuel production the Southern U.S. These findings are critical to insure economically and environmentally sustainable forest based bioenergy industries while meeting governmental GHG reduction thresholds as defined in the Energy Independence and Security Act (EISA).