Life cycle environmental impact assessment in palm oil industry from nursery, plantation, and mill: Case study in north Sumatera

The palm oil industry is a cornerstone of Indonesia's agricultural economy, yet its environmental consequences across the full production chain remain insufficiently quantified in an integrated manner. This study presents a comprehensive life cycle assessment (LCA) of an integrated palm oil production system at PTPN III, North Sumatra, Indonesia, encompassing three interconnected operational stages: oil palm nursery, plantation, and palm oil mill. Primary input-output inventory data were collected directly from operational records over a 12-month period (April 2022–March 2023) and complemented by secondary data from the ecoinvent v.3.8 database (allocation, cut-off by classification) for upstream background processes, with Indonesian (ID) market datasets applied to electricity and Rest-of-World (RoW) or Global (GLO) datasets applied to fertilizers, fuels, pesticides, and process chemicals; environmental impact assessment was conducted using SimaPro v.9.5. Eight midpoint impact categories were evaluated: acidification, eutrophication, Global Warming Potential (GWP), photochemical oxidation, abiotic depletion (elements), abiotic depletion (fossil fuels), water scarcity, and ozone layer depletion. Stage-specific functional units (1 kg of oil palm seedling, 1 kg of fresh fruit bunches (FFB), and 1 kg of crude palm oil (CPO) were used for unit-process modelling and hotspot analysis, and were linked to a final reference flow of 1 kg CPO through the FFB-to-CPO conversion (oil extraction rate 24.70%; 4.05 kg FFB per kg CPO, or 3.41 kg after mass allocation to CPO), plantation FFB production, and seedling requirement per hectare. Cradle-to-gate GWP was 0.60 kg CO₂-eq kg −1 CPO, to which plantation, mill operations, and nursery contributed 74.2%, 23.4%, and 2.3%, respectively. Results revealed that fertilizer application was the dominant environmental hotspot across the nursery and plantation stages, accounting for up to 98.53% of abiotic depletion (elements), 96.52% of GWP, and 96.30% of acidification at the plantation stage. At the palm oil mill stage, feedstock dominated most impact categories, particularly for abiotic depletion (elements; 99.18%, 2.19 × 10 −5 kg Sb-eq kg −1 CPO) and acidification (89.40%, 2.89 × 10 −3 kg SO₂-eq kg −1 CPO), reflecting the upstream intensification of plantation-stage burdens transmitted through the supply chain, while FFB waste (solid residues: empty fruit bunches, fibre, and shell) was identified as the primary contributor to eutrophication (80.00%), reflecting nutrient leaching from decomposing organic residue, whereas POME, accounted for separately as the ‘Liquid Waste’ flow, contributed a comparatively minor direct share (0.70%) owing to on-site effluent treatment prior to discharge. Water scarcity was co-driven by direct water consumption and fertilizer-embedded upstream water use across all stages. These findings provide a quantitative, multi-stage environmental profile of integrated palm oil production. Model results identify fertilizer inputs (nursery and plantation) and FFB waste (mill) as priority hotspots; an indicative screening suggests that a 10% reduction in fertilizer input could lower plantation-stage GWP by approximately 9.7%, assuming constant yield, which corresponds to about 2.6% of cradle-to-gate GWP per kg CPO because the studied plantation supplies 35.9% of the mill's FFB. A first-order sensitivity screening indicates precision fertilizer management (10% input reduction) could lower plantation-stage GWP by ∼9.7% (∼2.6% cradle-to-gate); nutrient-use-efficiency improvement (15–30% field-loss reduction) by 3.1–6.2%; and POME methane recovery (60–90% capture) by ≤0.07% under the metered baseline but up to 9–41% under a literature-bounded open-pond baseline, reflecting substantial uncertainty in the site's unmetered effluent inventory. FFB waste valorization was not separately quantified and remains a literature-based recommendation.