Recent development and economic analysis of glycerol-free processes via supercritical fluid transesterification for biodiesel production

In this review, recent development of glycerol-free supercritical fluid transesterification for biodiesel production was discussed. Glycerol-free supercritical fluid processes including single-step and two-step transesterification for biodiesel production were reviewed and subsequently the advantages and limitations were highlighted. Value-added by-product from glycerol-free production such as triacetin is more profitable compared with glycerol produced in conventional biodiesel production. Furthermore, the quality of biodiesel could be enhanced with the presence of triacetin, which is co-produced in supercritical methyl acetate transesterification reaction. However, there are concerns regarding the huge energy required to conduct supercritical reaction at elevated temperature and pressure. Hence, economic consideration in terms of equipment needed and profit margin were discussed in order to study the profitability of glycerol-free supercritical biodiesel production in the industry. Results showed that glycerol-free supercritical dimethyl carbonate process has the highest profit margin, indicating that it is economically competitive and could provide larger revenue to biodiesel producers.