From Agricultural Residue to Aviation Fuel: Classifying Oil Palm Trunk (OPT) and Reassessing Its Carbon, Sustainability and Policy Consequences

This qualitative literature review critically examines the proposed classification of oil palm trunk (OPT) as an agricultural residue and its implications for sustainable aviation fuel (SAF) development. Anchored in Indonesia’s October 2026 CAEP/14 policy agenda, it differentiates regulatory feedstock designation from lifecycle carbon intensity, physical sustainability and certification eligibility. A critical thematic synthesis of 55 peer-reviewed articles published during 2020–2026, complemented by ICAO policy documents, identifies five interacting issues: the economic definition of residue; the boundary between assigned indirect land-use change treatment and actual core lifecycle assessment; the effects of trunk extraction on soil organic carbon, nutrients and counterfactual biomass management; uncertainties in feedstock logistics and conversion technologies; and traceability, social inclusion and avoidance of double counting. The review argues that an assigned zero ILUC value is neither a measured zero-emission result nor a substitute for actual LCA. It proposes a five-gate assessment architecture—regulatory recognition, ecological extraction, engineering validation, carbon accounting and independent assurance—and a phased Indonesian evidence roadmap. Findings support carefully conditioned residue utilisation, accompanied by representative plantation trials, technology-specific assessments, auditable supply chains and safeguards for smallholders. Neither OPT classification approval nor a default OPT lifecycle emissions value is presumed as of 15 October 2026.