The potential for implementation of biorefineries, annexed to South African sugar mills was investigated to determine if this would improve sustainability of the sugar industry. There are opportunities to make more efficient use of the sugar cane plant as the bagasse is currently burnt in inefficient boilers and the leaves are burnt during harvesting. Simulations of selected biorefinery scenarios were generated using Aspen Plus®. The selected scenarios included a cellulosic ethanol process as the baseline. The potential to improve the economics of the ethanol scenario by co-production of higher value furfural and lactic acid were considered in two further scenarios. Furthermore, scenarios covering methanol synthesis, Fischer-Tropsch (FT) synthesis and butanol synthesis have been developed. In addition to chemicals, electricity for export to the grid was a co-product for all scenarios. The data from these simulations was used to generate an economic assessment of each scenario and subsequently used to carry out a sustainability assessment in terms of economic, environmental and social parameters. From the scenarios investigated, it was determined that biorefineries have the potential to reduce environmental impacts and create jobs. However, the economics of the investigated scenarios are not sufficiently robust to justify investment. There are multitudes of other scenarios that require consideration and there is ongoing technological development in this area.