Waste-to-energy plays a vital role in satisfying the world's future demands. Attentiveness over energy supply concerns and the environment has encouraged the research on waste to energy conversion. An alternative fuel produced from the renewable feedstock has received renowned attention. Fats, Oil, and Grease (FOG) is considered as the feedstock for the biodiesel production as it proves to be a cost-effective and heterogeneous raw material. The process modelling for transesterification of FOG using Aspen plus serves an essential function for investigating the process behavior, including performance evaluation. In this presentation, the process modelling for renewable fuel production with different catalyst/operating conditions will be presented. In addition, the other possible ways for energy production from the waste will be addressed.