Life cycle assessment of palm oil microemulsion-based biofuel

Microemulsion-based biofuel (ME50) is considered a promising renewable transportation fuel as well as a feasible substitute for diesel fuel. This study investigated the life cycle environmental assessment (LCA) of ME50 production from palm oil-diesel blends with ethanol and compared it with alternative biofuels, neat biodiesel (B100) and biodiesel-diesel blends (B50).

The LCA system boundary was separated into five stages: the oil palm cultivation stage, the palm oil production stage, the microemulsion production stage, the transportation stage, and the exhaust emissions in the use stage. Ten potential environmental impacts of the ME50 were evaluated, namely, acidification, eutrophication, global warming, ozone layer depletion, human toxicity, aquatic ecotoxicity, terrestrial ecotoxicity, land use, water depletion, and fossil depletion, by combining the CML 2000, IPCC 2007, Ecoindicator 99, and ReCipe methods in SimaPro (v. 7.1). Further, greenhouse gas (GHG) emissions from the microemulsion fuel production stage were calculated following the product carbon footprint (CFP) methodology.

It was estimated that 1.17 t or 45,800 MJ of microemulsion biofuel emits 3142 kg of CO₂eq through its life cycle. Refined palm oil and co-surfactant are crucial materials for the environmental performance of the microemulsion-based biofuel. Based on the environmental impact analyses, palm oil production from cultivation through the oil refinery exhibited the greatest environmental impacts in terms of eutrophication and water depletion. Surfactant use—a key element in the microemulsion formation—has a significant impact on land use and ecotoxicity-related impact categories. In comparing the impacts among ME50, B100, and B50, it was found that microemulsion fuel production has lower environmental impact than B100 and B50, except in terms of land use and fossil depletion.

Based on this analysis, the major environmental impact during the microemulsion biofuel production stage results from the raw materials used. The selection of appropriate materials and formula adjustment in the microemulsion fuel formulation are key in minimizing the potential impacts from biofuel production. Therefore, microemulsion biofuel is shown to be an environmentally sound technology for green production of biofuel.