Second Generation Ethanol Production Using Subcritical Water Hydrolysis on Sugarcane Bagasse and Straw

Subcritical water is potentially an efficient, environmentally-friendly alternative to acid and enzymatic hydrolysis of lignocellulosic biomass. Here, water was run over sugarcane bagasse and straw at 200°C, 15 MPa, and 20 mL/min with the resulting hydrolyzate being collected, analyzed, and fermented. Analysis of the hydrolyzate included determining the TRS and inhibitor concentrations via UV-Vis spectroscopy and HPLC. During fermentation, yeast yields were measured as a proxy for ethanol production using UV-Vis spectroscopy. Finally, a compositional analysis of the feedstock and reactor residue was carried out using TGA and FTIR. We found that subcritical water has the potential to compete with acid and enzymatic hydrolysis, being both efficient and more environmentally-friendly.