Life-Cycle GHG Emissions of Cassava-Based Bioethanol Production

This study aims to assess the life-cycle greenhouse gas (GHG) emissions of cassava ethanol production system focusing on utilization of biomass and biogas as energy sources in the steam production process. Scope of life cycle assessment is “cradle to gate” and the functional unit of this study is 1 liter of anhydrous ethanol produced. The use of biogas from wastewater treatment system for steam production greatly affects the GHG reduction. The GHG emissions of bioethanol plant that uses biogas from wastewater for steam production is 0.548 kg-CO2-eq/L-ethanol, while the bioethanol plant without biogas utilization is 1.031 kg-CO2-eq/L-ethanol. From the result, the utilization of biogas in steam production insignificantly reduce the GHG emission, if primary fuel in steam production is biomass. In contrast, using biomass such as wood chip and rice husk substitutes for fossil fuel as primary fuel in steam production greatly affects to GHG emission reduction (approximately 96% reduction compared to literature).