Sustainable Production of Bioenergy and Biochar from the Straw of High-Biomass Soybean Lines via Fast Pyrolysis

The straws of two high-biomass soybean lines developed at ARS for bioenergy were subjected to thermochemical conversion by fast pyrolysis. The objective was to evaluate the potential use of the straw Or the production of liquid fuel intermediates. The immediate goal was to demonstrate production of pyrolysis liquid that can be burned "as is" and/or potentially be upgraded to transportation grade fuel and at the same time produce biochar that can be deployed as a soil amendment. The goal supports the concept of on-farm biorefinery where food and bioenergy can be sustainably produced in a soybean farm system. The study shows that high yields of pyrolysis liquids (blood) can be efficiently produced from the soybean straws using the fluidized-bed fast pyrolysis technology. Free flowing biooils with heating values in excess of 20 MJ/kg were produced in yields of approximately 70 wt %. Accompanying this was 22 wt % mineral-rich biochar that can be returned to the soil and up to 10 wt % combustible gas with the potential to partially power the pyrolysis system. A sustainable farm system may be enhanced by the synergy between production of extra biomass in soybean cultivation, lignocellulosic biofuel production, production and use of carbon sequestering, soil-amending biochar in addition to nitrogen fixation by rhizobial bacteria. Although the findings are encouraging, actual data over several :years will be necessary to fully evaluate a potential soybean farm biorefinery system. by comprehensive life-cycle analysis. (C) 2010 American Institute of Chemical Engineers Environ Prog. 29: 175-183. 2010