Ethylic or methylic route to soybean biodiesel? Tracking environmental answers through life cycle assessment

Carlos Alberto Alejos Altamirano, Lídia Yokoyama, José Luiz de Medeiros and Ofélia de Queiroz Fernandes Araújo

Applied Energy, 2016, vol. 184, issue C, 1246-1263

Abstract: Biodiesel is a renewable fuel produced by transesterification of triacylglicerides (TAG) contained in vegetable oils and animal fats, to yield alkyl esters (biodiesel) and glycerin. Methanol is the main transesterification agent employed resulting in FAME (fatty acid methyl esters), which is primarily obtained from natural gas reforming (fossil source). Substitution of methanol by ethanol produces FAEE (fatty acid ethyl esters) and has the potential to render biodiesel a fully renewable fuel. Although renewability is a significant driving force for the proposed alcohol replacement, environmental performance of the alternative transesterification is questioned. The answer is herein sought through a comparative Life Cycle Assessment (LCA) of the two production chains. The study tracks CO2 emissions, energy efficiency, water and resources consumption, and environmental impacts (Acidification Potential – AP, Global Warming Potential – GWP, Eutrophication Potential – EP, and Human Toxicity Potential – TP). The boundaries of the biodiesel production chains extend from the extraction of raw-materials to its final use as transportation fuel in buses, applied to the Brazilian scenario. Results show that substitution of the methylic route with the ethylic route does not attribute significant environmental benefits. Furthermore, the ethylic route presents competitive advantages only in the category of GWP, and exhibits inferior performance in the remaining evaluated impact categories. Finally, a greater consumption of water and energy in the ethylic route in comparison with the methylic route is reported. Contrarily to a first judgement, the use of bioethanol as transesterification agent does not enforce sustainability of the biodiesel production chain.

Keywords: Soybean biodiesel; Transesterification; Bioethanol; Methanol; Environmental impacts; Life cycle assessment (search for similar items in EconPapers)
Date: 2016
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Citations: View citations in EconPapers (5)

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Persistent link: https://EconPapers.repec.org/RePEc:eee:appene:v:184:y:2016:i:c:p:1246-1263

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DOI: 10.1016/j.apenergy.2016.05.017

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