Palm biodiesel is widely considered as an environmental-friendly alternative to conventional diesel due to its capacity of carbon capture in plantation life-cycle phase. In Taiwan, due to the limited capacity of waste cooking oil, palm oil has been viewed as the potential low cost imported feedstock for producing biodiesel, which is obtains the oil feedstock in Malaysia and produces biodiesel in Taiwan. However, the impact of land-use change impact such as deforestation, and the characteristic of relatively lower-energy in combustion phase, are often neglected. This study aims to evaluate the cradle-to-grave life-cycle environmental performance of palm biodiesel. Phases in the life-cycle such as land- use change, plantation and milling for the Malaysia case and refining and fuel producing as well as engine combustion for the Taiwan case are investigated. The greenhouse gas (GHG) emission and energy consumption for the whole life-cycle are calculated as -28.29 kg CO2-equiv. and -23.71 MJ per kg of palm derived biodiesel. The payback time for using biodiesel is 14 and 95 years for rainforest and peat-forest cases, respectively. The GHG emission and payback time can further be reduced by adapting advanced oil-upgrading technologies like hydrotreating. Green diesel produced via hydrotreating has higher calorific value of 44 MJ/kg, higher cetane number 70-90 and lower CO2 emission compared to biodiesel produced via transesterification which has lower calorific value of 39.36 MJ/kg, lower cetane number of 65 and has higher carbon emission. For this reason, hydrotreating as an oil upgrading process has been adapted in this study to produce the green diesel.

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