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Sustainability 2018, 10(1), 127; https://doi.org/10.3390/su10010127

Catalyst-Free Biodiesel Production Methods: A Comparative Technical and Environmental Evaluation

1
Department of Physics, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
2
Department of Food Science, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand
*
Author to whom correspondence should be addressed.
Received: 25 October 2017 / Revised: 7 December 2017 / Accepted: 3 January 2018 / Published: 8 January 2018
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Abstract

In response to existing global focus on improved biodiesel production methods via highly efficient catalyst-free high temperature and high pressure technologies, this study considered the comparative study of catalyst-free technologies for biodiesel production as an important research area. In this study, therefore, catalyst-free integrated subcritical lipid hydrolysis and supercritical esterification and catalyst-free one step supercritical transesterification processes for biodiesel production have been evaluated via undertaking straight forward comparative energetic and environmental assessments. Energetic comparisons were undertaken after heat integration was performed since energy reduction has favourable effects on the environmental performance of chemical processes. The study confirmed that both processes are capable of producing biodiesel of high purity with catalyst-free integrated subcritical lipid hydrolysis and supercritical esterification characterised by a greater energy cost than catalyst-free one step supercritical transesterification processes for an equivalent biodiesel productivity potential. It was demonstrated that a one-step supercritical transesterification for biodiesel production presents an energetically more favourable catalyst-free biodiesel production pathway compared to the integrated subcritical lipid hydrolysis and supercritical esterification biodiesel production process. The one-step supercritical transesterification for biodiesel production was also shown to present an improved environmental performance compared to the integrated subcritical lipid hydrolysis and supercritical esterification biodiesel production process. This is because of the higher potential environment impact calculated for the integrated subcritical lipid hydrolysis and supercritical esterification compared to the potential environment impact calculated for the supercritical transesterification process, when all material and energy flows are considered. Finally the major contributors to the environmental outcomes of both processes were also clearly elucidated. View Full-Text
Keywords: waste reduction algorithm; potential environmental impact; catalyst-free biodiesel production; heat integration waste reduction algorithm; potential environmental impact; catalyst-free biodiesel production; heat integration
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Okoro, O.V.; Sun, Z.; Birch, J. Catalyst-Free Biodiesel Production Methods: A Comparative Technical and Environmental Evaluation. Sustainability 2018, 10, 127.

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