Technoeconomic analysis of biodiesel and ethanol production from lipid-producing sugarcane and sweet sorghum
Genetically modified lipid-producing sugarcane (lipid-cane) and lipid-producing sorghum (lipid-sorghum) have great potential for producing biodiesel due to their ultra-high yields compared to traditional oil seeds. Meanwhile, the remaining sugar in lipid-cane and lipid-sorghum can be used to produce ethanol, another important biofuel. This study proposes an integration of lipid-sorghum into a lipid-cane processing plant by using the existing machinery during the lipid-cane off-season. Technoeconomic models were developed to estimate the technical and economic feasibility of producing biodiesel and ethanol from lipid-cane and lipid-sorghum. Different lipid concentrations in harvested stems (0, 5, 10, and 20%, dry basis) were assumed based on the current research and future predictions to improve lipid concentrations in lipid-cane and lipid-sorghum. By integrating lipid-sorghum into the lipid-cane processing plant for 60 days during the lipid-cane off-season, the production costs of biodiesel and ethanol decreased by $0.03/L and $0.02/L, respectively, due to the improved capital utilization efficiency. Furthermore, processing lipid-sorghum during the lipid-cane off-season increased the annual biofuel (biodiesel and ethanol) production and revenue by 20-30% in different scenarios. The processing plant had an international rate of return (IRR) of 24.0% when using lipid-cane (20% lipid) as feedstock; and the IRR value increased to 29.2% when integrated with lipid-sorghum during the lipid-cane off-season. The technoeconomic analysis shows that integration of lipid-cane and lipid-sorghum can be a promising path to produce biodiesel and ethanol economically. A sensitivity analysis was also performed to determine the variation of the IRR with the key parameters applied in the economic analysis.