Scaled-Up Microwave-Assisted Continuous Pyrolysis for Mixed Plastic Waste Valorization: Process Design and Techno-Economic Analysis toward Technology Industrialization

Abstract

The industrial deployment of plastic waste pyrolysis is still limited by capital intensity, electrification costs, and uncertainty in product value and scale-dependent profitability. Here, we report a parametric techno-economic analysis (TEA) of continuous microwave-assisted pyrolysis (MW-Pyr) for mixed, polyolefin-rich plastic waste, benchmarked against an existing pilot installation at CIRCE Technology Centre (Spain). Plant capacities from 2000 to 20,000 t/y and pyrolysis oil selling prices from 500 to 1200 €/t were evaluated in terms of CAPEX, OPEX, payback period (PBP), and return on investment (ROI). Scale-up from pilot to industrial conditions was performed using power-law relationships (β = 0.7 for capital; μ = 0.6 for labor). For a reference capacity of 10,000 t/y, CAPEX was estimated at 19.4 M€, while annual OPEX accounted for 10–15% of CAPEX. Under a base-case oil price of 850 €/t, the minimum economically attractive scale is ∼6000 t/y to exceed ROI >6.7% (15-year asset lifetime) and meet typical industrial payback expectations, whereas capacities ≤4000 t/y remain unfavorable under conservative assumptions. Sensitivity analysis identifies oil yield and CAPEX uncertainty as the dominant risk drivers, with pessimistic assumptions severely extending PBP and deteriorating ΔROI by up to 38% at large scales, while favorable external conditions yield ΔROI improvements of up to 45% and meaningful PBP reductions across all scenarios evaluated. Scenario analysis indicates that partial CAPEX support (15–30%) and char valorization can materially improve cash generation and derisk first-of-a-kind deployment. Overall, the study quantifies actionable scale–price thresholds and clarifies when electrified MW-Pyr can competitively supply circular hydrocarbon feedstocks to petrochemical value chains.