Synthesis of South Africa’s Biomass to Bioethanol Supply Network

Abstract

South Africa produces synthetic ethanol and to date there are no commercial bioethanol production plants in operation in the country. Sugarcane, as well as residues from sugarcane, maize, sorghum, wheat and barley are among the acceptable bioethanol feedstocks in South Africa. As the feedstock cultivation areas are scattered over a wide geographical land area, and the potential bioethanol feedstocks have low energy density, there is a need to locate the processing facilities in strategic positions such that production and logistic costs and greenhouse gas (GHG) emissions due to transportation are minimized. To address the above mentioned challenges associated with bioethanol production in South Africa, a mathematical programming approach for the synthesis of optimal bioethanol supply network is developed. It accounts for sugar demands, production of bioenergy (ethanol, electricity and heat) and other byproducts, various feedstocks and their geographical distributions, etc. Various processing technologies for ethanol production are considered and two data sources for availabilities of feedstocks are used. Synthesis is performed by maximizing the economic objective, measured by annual profit. Evaluation of greenhouse gas (GHG) emissions is also performed. Based on the results obtained, it would be possible, in terms of economics, to meet and surpass the 2 % target penetration of biofuel into the South African national liquid fuel supply stipulated by the government.