Biodiesel production through sulfuric acid catalyzed transesterification of acidic oil: Techno economic feasibility of different process alternatives

Abstract

Biodiesel is renewable fuel produced from fats and oils. When compared to conventional diesel fuel, it has considerable environmental benefits. However, its extensive use is hindered by high cost of production, mainly due to cost of feedstock. Among the different biodiesel production routes, acid catalyzed transesterification enables to use feedstock with higher free fatty acid content (cheaper feedstock). The absence of soap formation while using acid as a catalyst also simplifies the downstream separation and purification processes. In this study, a homogeneous sulfuric acid catalyzed transesterification of acidic oil is designed into four process scenarios based on four different downstream process routes.The conceptual design and simulation of these process alternatives have been carried out using Super Pro and Aspen Plus software. These process models were used to evaluate the techno economic competitiveness of the four different scenarios. In the four process scenarios, all reactors for biodiesel production have been designed to have the same reaction conditions and the same amount of oil feedstock input. The difference of the scenarios was only on the arrangements and type of downstream process equipment required to get fuel grade biodiesel. The technical performances have been evaluated based on quality and quantity of products as well as the amount of biodiesel produced per feedstock consumed. The specific economic parameters considered were Unit Production Cost, NPV, IRR (after tax), and Payback time. The process scenario with ethanol recovery after catalyst neutralization and glycerol separation using decanting just before biodiesel purification has better technical and economic performances. Whereas the double reactor scenario shows much better technical performances with very low economic feasibility.