Life cycle assessment of bioethanol production from sugarcane bagasse using a gasification conversion Process: Bibliometric analysis, systematic literature review and a case study

Abstract

• A coupling of LCA with process simulation was used for the environmental evaluation of bioethanol production. • A yield of 0.42 L bioethanol (97% pure) per kg of bagasse was obtained for producing 1,000 L/h. • A cradle-to-grave LCA scope quantified a GWP impact of ∼26.7 kg CO 2-eq/L. • Biofuel use in vehicles (70%) and biofuel production (25%) were major contributors for the GWP category. • A cradle-to-gate LCA scope quantified a lower GWP impact of ∼8.4 kg CO 2-eq/L. • For other CML impacts, biofuel production (ADP, MAETP, EP, ODP, and POP), and material extraction (LC, HTP, FAETP and TETP) were major contributors. A new integrated methodology to estimate environmental impacts of bioethanol production from sugarcane bagasse was developed for Mexico. The methodology included five modelling phases: (i) a bibliometric analysis and systematic literature review using peer-review journals, and world citation databases; (ii) a simulation of the gasification process to produce bioethanol; (iii) a life cycle inventory gathered from simulation, literature and Ecoinvent data sources; (iv) a life cycle assessment (LCA) of the bioethanol production stages (raw material extraction, transportation, sub-product extraction, biofuel production, biofuel use in vehicles, and refinery construction and decommissioning), the cumulative energy demand, and water footprint; and (v) the analysis of the major environmental burdens. After a comprehensive searching in Web of Science and Scopus, 55 articles dealing with the state-of-art of the main research subjects for the time period 2008 – 2021 were compiled. The bioethanol production was simulated by using the Aspen Plus v11 software, where a yield of 0.42 L bioethanol per kg of bagasse was estimated for a production of 1,000 L/h and a purity of 98.6%. In response to the limitations observed in previous environmental evaluations conducted for the bioethanol production, the present LCA work was carried out from a robust cradle-to-grave perspective to quantify the major environmental burdens, and the cumulative energy demand and water footprints. Biofuel use in vehicles (70%) and biofuel production (25%) stages present the highest contributions for the GWP impact category, which was totally quantified as ∼26.7 kg CO 2 -eq/L. When a cradle-to-gate perspective was modelled, this amount was significantly reduced (∼8.4 kg CO 2 -eq/L). For other impact categories evaluated, the highest contributions corresponded to the biofuel production (55% - 95% for ADP, MAETP, EP, ODP, and POP), and raw material extraction stages (70% - 100%: LC, HTP, FAETP and TETP). A comparison among previous LCA studies reported for gasification was discussed. This investigation constitutes the first study applied for bioenergy in Mexico from a successful coupling of LCA with process simulation as strategic tools for the evaluation of the environmental sustainability of bioethanol production.