Life cycle assessment of bioethanol production from sugarcane bagasse: A case study for Mexico

Abstract

According to the United Nations Sustainable Development Goals (SDGs) to 2030, significant efforts would be required to increase the production of more affordable and clean energies to achieve net-zero emissions in energy systems (SDG7), while executing climate actions (SDG13) to limit global temperature increases below 2°C. According to IEA (International Energy Agency), in 2018 transport represented the second most pollutant sector worldwide, with 25% (8,258 Mt CO2) of total CO2 emissions (33,513.3 Mt CO2) globally; therefore, its decarbonization has become one of the most challenging targets. Bioenergy represented one-tenth of the total primary energy supply worldwide, then it is considered a viable alternative to diversify the worldwide energy mix supply. Thus, second-generation biofuels will potentially play a more significant role in the transport sector. In Mexico, bioenergy represents 5% of total primary energy production. Therefore, this work aims to assess the environmental sustainability of bioethanol production from a second-generation feedstock as sugarcane bagasse. This research considered a novel integrated methodology based on a cradle-to-grave life cycle perspective, including four main stages: i) a systematic literature review, ii) data collection, iii) process simulation of the chemical conversion via gasification, iv) Life Cycle Assessment (LCA) (based on the ISO 14040-44 framework) interpretation, and v) validation of results. As part of the results, under a cradle-to-grave boundary, the carbon footprint was 26,689 kg CO2eq with a defined functional unit of 1,000 L of bioethanol. The majority of the CO2eq emissions were attributed to the bioethanol production with 25.3 % and use in vehicle stages with 68.7 %. As conclusions, the results obtained in this study and comparing with other studies suggest that Mexico has a great potential for producing second-generation biofuels. Nevertheless, plans and actions as scenarios, improvements, and further sustainability assessment, as proposed in this work, need to be considered in future work.