2017 ASHS Annual Conference

Year-round availability of sweetpotato [SP; Ipomoea batatas (L) Lam], sweet sorghum (SS; Sorghum bicolor) and sugarcane (SC; Saccharum officinarum) as feedstocks for ethanol production is among potential challenges for the bio-refinery industry. All three can be grown and processed complimentarily, which would ensure a steady supply of feedstock, thereby helping to extend the number of days an ethanol plant could operate. The goal of this project was to develop an integrative process of supplying multiple feedstocks at pilot-scale, to ensure a continuous year-round supply and inputs and outputs evaluated. Both laboratory and pilot-scale experiments were conducted to: 1) estimate the potential ethanol production from SS, SC, and SP by comparing ethanol concentrations among species; and 2) determine the feasibility of continuous ethanol production using multiple feedstocks. A randomized complete block design with three replications was used. Five SS cultivars (K.N. Morris, Dale, MSIE, Della, Sugar Drip),and three SC cultivars (TU White, TU Blue, TU Green), singly or as mixed feedstocks were analyzed for Brix%, dry matter, total sugars and ethanol concentration. Brix% ranged from 18 to 20% for SS and from 17 to 19% for SC. Sucrose was the main sugar in SS, SP, and SS except for (M8IE, Della) where glucose was the main sugar. Average ethanol concentration was 86, 78 and 51 g^.L^-1 for SS, SC, SP, respectively, and 80 g^.L^-1 as mixed feedstocks.. Percent ethanol recovery at both laboratory and pilot-scale for SS, SC, and SP were 7.3, 7.2, and 1.8%, at pilot-scale and 8.5, 7.7, 5.7% at laboratory-scale, respectively. The fermentation procedure utilizing Saccharomyces cerevisiae was similar for all species, except that SP samples were hydrolyzed. Continuous ethanol production using SS, SC at pilot scale was feasible. However, there are several limitations to the inclusion of SP and further work is being done to overcome them.