Process alternatives for bioethanol production from Organosolv pretreatment using lignocellulosic biomass

Organosolv pretreatment makes use of ethanol as a solvent to remove lignin and render the cellulose and hemicellulose present in the biomass available for conversion. However, solvent recovery is a crucial step to make organosolv pretreatment a competitive and reliable alternative for second generation bioethanol production. We used Aspen Plus v8.0 to simulate an initial organosolv pretreatment case based on published experimental works and proposed 4 different alternatives for the solvent ethanol recovery. Total energy consumption, ethanol productivity, ethanol concentration after fermentation, capital costs, variable costs and minimum ethanol selling price (MESP) were evaluated for the selection of the best design for the process. Furthermore, energy targets were calculated for the scenarios to investigate the saving potentials in the variable costs and were accounted for new MESP calculations. Ethanol productivity and recovery was similar for all the cases evaluated. The capital cost calculated for the base case was 20.8 million dollars and the total energy consumption was 732 MW, with a MESP of 1.117 $/kg of ethanol. The best process alternative with energy integration obtained savings of almost 30 % in the MESP, totalizing 0.782 $/kg of ethanol and the total energy consumption was 488 MW.