Energy consumption analysis on pilot-scale plant of fuel ethanol production from sweet sorghum stalk by solid state fermentation

The technological process of a pilot-scale plant for fuel ethanol production from sweet sorghum stalk by solid state fermentation was described and energy consumptions of ethanol and byproduct production processes were analyzed. By applying the technology of solid-state fermentation, the conversion rate of ethanol reached 95.8% of the theoretical value. In addition, by utilizing the stalk bagasse comprehensively, the recycling and reusing of the waste heat was realized. As a result, the conversion process had an environment friendly characteristics. The annual yields of the anhydrous ethanol, protein feed and fiber pulp from the stalk were 1 000 t/a, 1 500 t/a and 5 000 t/a, respectively. Result showed that the total energy consumption of the pilot-scale plant was 4.31×106kW·h/a when waste heat recovering was considered. The energy consumptions per unit production of anhydrous ethanol, protein feed and fiber pulp were 2759.67 kW·h /t, 36.86 kW·h /t, and 298.41 kW·h/t, respectively. The recovered waste heat in anhydrous ethanol production process was 8.9×105 kW·h/a. The energy recovering rate during ethanol production from sweet sorghum stalk was 62.9%, which was higher than that of ethanol production from food materials such as corn.