Solar-Energy Driven Simultaneous Saccharification and Fermentation of Starch to Bioethanol for Fuel-Cell Applications

A solar reactor was designed to perform the conversion of starch to ethanol in a single step. An aqueous starch solution (5wt%) was fed into the reactor bed charged with Baker's yeast (Saccharomyces cerevisiae) and amylase, resulting in approximately 2.5wt% ethanol collected daily (ca. 25mLday(-1)). A significant amount of ethanol (38g) was collected over 63days, corresponding to 84% of the theoretical yield. The production of ethanol without additional energy input highlights the significance of this new process. The ethanol produced was also demonstrated as a potential fuel for direct ethanol fuel cells. Additionally, the secondary metabolite glycerol was fully reduced to a value-added product 1,3-propanediol, which is the first example of a fungal strain (Baker's yeast) converting glycerol insitu to 1,3-propanediol.