Recent trends of biodiesel production from animal fat wastes and associated production techniques

Non-edible feedstocks such as animal fat wastes (AFWs) have recently increased in popularity as alternatives to vegetable oils in the production of biodiesel. They are low cost, mitigate environmental damage and increase the quality of the resultant biodiesel fuel (low NOx emissions, high Cetane number and oxidative stability). Therefore, AFWs are an excellent feedstock for biodiesel production. Here we provide a comprehensive review trends and techniques in biodiesel production from AFWs. A critical overview of homogeneous and heterogeneous (one- or two-step) catalytic transesterification of AFWs is presented. Similarly, enzyme-catalyzed transesterification and the application of supercritical fluids conversion techniques in the production of biodiesel from AFWs are thoroughly assessed. Finally, cutting edge advances in assisted transesterification processes for biodiesel production are critically reviewed.