Comparative Life Cycle Assessment of the Use of Coconut Biodiesel Blends and Neat Diesel in Public Utility Jeepneys in Metro Manila, The Philippines

Abstract

This study aims to compare the CO₂ emissions from conventional diesel and coconut biodiesel blends from raw material extraction up to use as fuel for public utility jeepneys (PUJs) in the Philippines. This work used the process-based LCA approach with 1 kilometer distance travelled by PUJs as the functional unit. The kg CO₂ emissions from coconut farming and harvesting until the use phase of the coconut biodiesel blends in Metro Manila jeepneys were estimated in this work. The calculated emission factor of Coconut Methyl Ester (CME) from its fatty acid composition is 2.5539 kg CO₂ per 1 kg CME. The total CO₂ emissions in the life cycle of 2% CME blend (B2) and 5% CME blend (B5) were lower by 0.767% and 5.37%, respectively, compared to those from life cycle of neat diesel. In the life cycle of neat diesel, B2 blend, and B5 blend, the use phase contributed 75-78% of the CO₂ emissions. The kg CO₂ emissions from Metro Manila public utility jeepneys decreased from 0.400kg/ km using neat diesel to 0. 381 kg/km and 0.363 kg/km using B2 blend and B5 blend, respectively. In the life cycle of coconut biodiesel from raw material extraction to CME production, 52-58% of CO₂ emissions come from the production of material inputs to the trans-esterification process. Three main recommendations are proposed by this work: (1) Extend the LCA to higher blend percentage. This entails measurement of specific fuel consumption of jeepneys using this fuel. (2) Increase engine efficiencies of Public Utility Jeepneys to reduce fuel consumption and realize higher CO₂ emission reductions. (3) Further studies on optimization of mole ratio of methanol to coconut oil in trans-esterification process must be done. Explore use of methanol from sources-other than natural gas- with less CO₂ emissions.