A review of current technology for biodiesel production: State of the art

• Various technologies employed for biodiesel production to date were described and reviewed.
• The uses of heterogeneous catalysts in continuous process were suggested and may be sustainable.
• Heterogeneous catalysts from biomass sources are environmentally and economically viable but underexplored.
• Reactive distillation has the major advantage of combining the reaction and separation stages in a single unit.
• The simulated work done by many authors on reactive distillation needs to be supported by some experimental work.

This article reviews various technologies that have been used for biodiesel production till date, with a view to comparing commercial suitability of these methods on the basis of available feedstocks and associated challenges. This review shows that while emphasis is on the use of micro alga oil sources, the viability of the economics of the process is still in doubt. Homogenously catalyzed processes are the conventional technologies. However, their large-scale applicability is compromised due to their characteristic challenges. Batch processes and continuous processes are used for industrial purposes with typical capacity of 7.26–7.5 Gg y−1 and 8–125 Gg y−1 respectively, and heterogeneous catalysis may be sustainable for the continuous processes. Heterogeneous catalysts from renewable sources may be both environmentally and economically viable. Reactive distillation has the major advantage of combining the reaction and separation stages in a single unit, thereby significantly reducing capital costs and increasing opportunities for heat integration. This paper is a comprehensive overview of current technologies and appropriate options for scale-up development, providing the basis for a proposal for the exploitation of heterogeneous catalysts from natural sources to optimize biodiesel production.