Economic analysis of bioethanol and electricity production from sugarcane in South Africa

摘要

An economic analysis for ethanol and electricity production in the sugarcane crushing industry in South Africa through first- and second-generation technologies, and integration strategies was carried out. The analysis included capital allowances to upgrade the energy efficiencies of existing sugar mills, to allow co-production of electricity, production of second-generation ethanol from hemicellulose, and export of lignocellulose residues from these facilities. Methodologies included mass and energy balances in Aspen Plus and economic models in MS Excel to determine the required selling prices for electricity, sugarcane residues and ethanol, for these investments. The required selling price for electricity for the sugarcane crushing industry was US$ 97/MWhr, while that of bagasse residues was US$ 90/ton. A first-generation ethanol plant with electricity co-generation from bagasse has an ethanol selling price of US$ 0.84/I, which was highly dependent of the cane price, and reduced significantly when second-generation production from hemicelluloses of bagasse and trash was incorporated. The selling price of US$ 0.38/I for integrated second-generation ethanol at a sugar mill was the lowest, but however, was highly dependent on technological efficiency. Standalone second generation ethanol was unfeasible due to the costs of the infrastructure needed to provide bagasse as a feedstock. (C) 2017 Society of Chemical Industry and John Wiley & Sons, Ltd