Technologies of bio-diesel production: a state of the art review

The fast depletion of fossil fuel, with increasing awareness toward pollution free environment, the renewable and sustainable energy resources are in high demand. Consequently, bio-diesel is considered as a feasible substitute for the nonrenewable source of diesel fuels and there is a huge market for alternative fuels across the globe. In this review, the basic means of making bio-diesel from animal fats and vegetable oils are discussed. The vital parameters which influence the overall cost of bio-diesel production such as accessibility, types of raw material, techniques involved, types of acid-catalysts, and operation costs are stated elaborately. The various raw materials for the production of biofuel, and corresponding output are described and the different factors like reaction rate and processing technology on homogeneous and heterogeneous catalyzed trans-esterification are compared based on the performance parameters. The heterogeneous catalytic trans-esterification for bio-diesel production from bio-oil has been reviewed exhaustively. Different types of trans-esterification mechanisms by several researchers have also been compared and reported.