Integrated Valorization of Plastic Waste into Synthetic Fuels and Electricity via Multi-Stage Upgrading: Process Modeling and Techno-Economic Analysis

Abstract An integrated process for the valorization of 1000 kg/h of heterogeneous plastic waste (Plasmix) into hydrogen, purified CO2, light and heavy liquid fuels, and electricity was developed and simulated using Aspen Plus. The process combines non-catalytic pyrolysis with sequential syngas upgrading, tar catalytic conversion, and extensive heat integration to maximize product recovery and economic performance. In the pyrolysis stage (600 °C, 12 bar), Plasmix is efficiently converted into gas, tar, char, and wastewater, with the gaseous fraction representing the largest product share (42.1%), followed by tar (23.0%), char (20.6%), and water (14.3%). The syngas stream is upgraded via reforming, water–gas shift, CO2 separation, and pressure swing adsorption to produce hydrogen (59 kg/h) and purified CO2 (533 kg/h), while the tar fraction is converted into liquid fuels, yielding 228 kg/h of light fuel and 23 kg/h of heavy fuel. Process integration enables substantial energy recovery, resulting in a net electricity export of approximately 18.2 MW. Economic evaluation shows a fixed capital investment of 12.21 M$, with annual revenues of 15.50 M$/year and operating expenditures of 5.33 M$/year, confirming strong baseline profitability. Sensitivity analysis identifies hydrogen and electricity selling prices as the dominant economic drivers, whereas the plastic waste fee provides a secondary contribution to profitability enhancement. Monte Carlo analysis further confirms robust financial performance under uncertainty, with predominantly positive net present values ranging from –33.6 to 129.9 M$, indicating limited downside risk and strong overall economic resilience. The internal rate of return varies between 0 and 52%, while discounted payback periods range from 0.7 to 10 years depending on market conditions. These results demonstrate that the proposed process achieves high mass valorization efficiency and economically resilient performance, providing a promising pathway for sustainable plastic waste-to-energy and waste-to-fuels integration within a circular carbon framework.