Environmental and economic trade-offs in conventional vs. additive manufacturing: A life cycle study of pump impeller production

This study presents a comparative sustainability assessment of pump impeller production using conventional manufacturing (CM–sand casting) and additive manufacturing (AM), specifically Directed Energy Deposition (DED) by integrating life cycle assessment (LCA) and net present value–based life cycle costing (NPV-LCC) within a cradle-to-gate framework. Environmental impacts were evaluated using the Centrum voor Milieukunde Leiden (CML) method, while economic performance was analysed through time-dependent cost modelling, Monte Carlo uncertainty analysis, and scenario-based evaluation. The results show that CM exhibits 46% higher abiotic depletion potential due to material losses and yield-related inefficiencies, whereas AM demonstrates 54% higher global warming potential than CM (33.7 vs. 15.5 kg CO 2 eq per impeller) because of its electricity-intensive manufacturing process. Electricity consumption contributes approximately 75% of the total environmental burden in AM. Economically, the NPV-LCC analysis indicates baseline lifecycle costs of approximately €175 per impeller for CM and €1265 per impeller for AM. Monte Carlo sensitivity analysis reveals that material cost and yield rate dominate CM cost variability (ρ ≈ 0.8), while build duration (machine usage time) and energy consumption are the most influential drivers for AM (ρ ≈ 0.85 and ρ ≈ 0.75, respectively). Scenario analysis demonstrates that process efficiency improvements and increased utilization provide greater economic benefits for AM than renewable energy substitution alone. Overall, the findings indicate that AM functions as a complementary manufacturing route whose sustainability performance depends strongly on lifecycle-oriented process optimization strategies.