The farm to biorefinery continuum: A techno-economic and LCA analysis of ethanol production from sweet sorghum juice

This paper describes the economic, environmental, and energy issues of the farm to biorefinery continuum related to production of ethanol from soluble sugars recovered from sweet sorghum using the BE3 (bioenergy economics, energy, and environmental) model methodology. A comparative analysis of five process configurations was conducted to determine how process decentralization affects the total production system. An increased integration of on-farm processing resulted in a moderate increase in the breakeven sales price of ethanol ($0.08/L), however the substantial increase in value-added agricultural practices (approximately 180%) can offer greater returns to the farm operation. Benefits outside the scope of this analysis related to decentralized processing include: increased rural development, reductions in transportation requirements, additional income to farmers, and dissipation of some environmental impacts. Using a single parameter sensitivity analysis for those process configurations the greatest economic impacts were found to be related to conversion efficiency, crop yield, and press efficiency. Conservative values were used throughout the process modeling procedure (e.g. crop yield, Brix level of juice, conversion efficiency, and by-product usage), yet with system optimization, breakeven sales price could be significantly decreased.