Review A review of current technology for biodiesel production: State of the art E.F. Aransiola*, T.V. Ojumu, O.O. Oyekola, T.F. Madzimbamuto, D.I.O. Ikhu-Omoregbe Department of Chemical Engineering, Cape Peninsula University of Technology, Bellville Campus, Cape Town 7535, South Africa article info Article history: Received 2 July 2012 Received in revised form 7 October 2013 Accepted 23 November 2013 Keywords: Biodiesel Homogeneous catalyst Heterogeneous catalyst Reactive distillation Biomass source abstract 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 7.26e7.5 Gg y 1 and 8e125 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 hetero- geneous catalysts from natural sources to optimize biodiesel production. ª 2013 Elsevier Ltd. All rights reserved. 1. Introduction The consciousness of cleaner production technology is increasing globally. The need for an alternative to fossil fuels has engendered extensive research in recent years. Fossil fuels are non-renewable sources of energy which generate pollut- ants and are linked to global warming, climate change and even some incurable diseases. The impending challenges and the environmental implications of fossil fuels have been reviewed widely in the literature [1e3]. Biodiesel has been identified as one of the notable options for at least com- plementing conventional fuels. Its production from renewable biological sources such as vegetable oils and fats has been reviewed widely [4e7]. Its advantages over petroleum diesel cannot be overemphasized: it is safe, renewable, non-toxic, and biodegradable; it contains no sulphur; and it is a better lubricant. In addition, its use engenders numerous societal benefits: rural revitalization, creation of new jobs, and reduced global warming [8]. Its physical properties have been reviewed * Corresponding author. Tel.: þ27 460 3162; fax: þ27 21 460 3854. E-mail addresses: aransiola4@yahoo.com, aransiolaef@gmail.com (E.F. Aransiola). Available online at www.sciencedirect.com ScienceDirect http://www.elsevier.com/locate/biombioe biomass and bioenergy 61 (2014) 276 e297 0961-9534/$ e see front matter ª 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.biombioe.2013.11.014