Material flow and sustainable utilization of end-of-life motorcycles under Taiwan's vehicle electrification policy

Motorcycle electrification is transforming transportation systems in regions where two-wheelers dominate mobility, raising new challenges for end-of-life vehicle (ELV) management. Despite extensive ELV research on passenger vehicles, integrated assessments of material flows, comparative recyclability, and design sensitivity for electric and combustion motorcycles remain scarce, particularly in motorcycle-dominant systems. This study evaluates the recycling performance of end-of-life motorcycles (ELMs) in Taiwan using material flow analysis and dual recyclability assessment methods (ISO 22,628 and UNIFE), comparing combustion engine motorcycles (CEMs) and electric motorcycles (EMs) across multiple treatment scenarios. Under the ISO 22628 business-as-usual scenario, CEMs achieved a reuse and recycling rate of 82.6%, while EMs reached only 67.6%, primarily due to their higher proportion of composite plastics and the presence of lithium-ion batteries accounting for 16% of vehicle mass. The more conservative UNIFE assessment further revealed that neither motorcycle type consistently satisfies the international 95% reuse and recovery target, highlighting that theoretical rate often masks a reliance on thermal recovery rather than true material circularity. Scenario analysis indicates that manual dismantling, particularly of plastic components, can raise plastic recycling rate exceeding the 25% recycled-content threshold in EU regulation COM(2023)451. Sensitivity analysis identified upstream eco-design as the most effective intervention, improving EM recyclability by 4.6%, whereas downstream processing variations produced changes below 2.0%. Material flow projections indicate approximately 9,000 tons of annual LIB waste by 2050. The results suggest that improving ELM circularity requires prioritizing upstream material simplification through eco-modulated EPR incentives rather than relying solely on downstream recycling process optimization.