Determination of GHG contributions by subsystems in the oil palm supply chain using the LCA approach

Purpose With increasing attention on sustainable development, the environmental and social relevance of palm oil production are now important trade issues. The life cycle assessment (LCA) study of Malaysian oil palm products from mineral soils including palm biodiesel was aimed to provide baseline information on the environmental performance of the industry for drawing up policies pertaining to the sustainable production. The share of greenhouse gas (GHG) contribution by the various subsystems in the oil palm supply chain is considered here. Materials and methods The life cycle inventory data for the study were collected based on subsystems, i.e., gate-to-gate. The subsystems include activities in oil palm nurseries and plantations, palm oil mills, refineries, biodiesel plants and the use of biodiesel in diesel engine vehicles. Two scenarios were considered: extraction of crude palm oil (CPO) in a mill without and with a system for trapping biogas from palm oil mill effluent (POME). Inventory data were collected through questionnaires. On-site visits were carried out for data verification. Background data for resource exploitation and production of input materials were obtained through available databases and literature. Foreground data for all subsystems were site-specific data from nurseries, plantations, palm oil mills and refineries and biodiesel plants in Malaysia. Results and discussion Using a yield of 20.7 t oil palm fresh fruit bunches (FFB)/ha, the results showed that the production of 1 t of FFB produced 119 kg CO2 eq. The production of 1 t of CPO in a mill without and with biogas capture emitted 971 and 506 kg CO2 eq, respectively. For the production of 1 t of refined palm oil in a refinery which sourced the CPO from a mill without biogas capture and with biogas capture, the GHG emitted was 1,113 kg and 626 kg CO2 eq, respectively. For palm biodiesel, 33.19 and 21.20 g CO2 eq were emitted per MJ of biodiesel produced from palm oil sourced from a mill without and with biogas capture, respectively. Conclusions GHG contribution by the nursery subsystem was found to be minimal. In the plantation subsystem, the major sources of GHG were from nitrogen fertilizers, transport and traction energy. For the mill, biogas from POME was the major contributor if biogas was not trapped. Excluding contribution from upstream activities, boiler fuel and transport were the major sources of GHG in the refinery subsystem. In the biodiesel subsystem, activities for production of refined palm oil and methanol use were the most significant contributors.