Municipal solid waste to liquid transportation fuels, olefins, and aromatics: Process synthesis and deterministic global optimization

• A process synthesis superstructure is introduced for the conversion of MSW.
• A deterministic global optimization algorithm determines the optimal process topology.
• Nine case studies illustrate the process synthesis framework described.
• Parametric analysis is carried out to investigate the effect of the tipping fee.

This paper proposes a comprehensive process superstructure-based approach toward the sustainable production of liquid transportation fuels, olefins, and aromatics from municipal solid waste, MSW. A deterministic global optimization based branch-and-bound algorithm is utilized to solve the resulting nonconvex mixed-integer nonlinear optimization model. Several novel, commercial, and competing technologies are modeled within the proposed framework. The production of higher-value hydrocarbons proceeds through a synthesis gas intermediate that can be subsequently converted via Fischer–Tropsch refining or methanol synthesis. Simultaneous heat, power, and water integration is included in every process design to minimize utility costs. For every proposed process design, two profitability metrics, the overall profit and the net present value, are calculated. The optimal process topologies that produce liquid fuels and high-value chemicals at the highest profit are illustrated for several case studies. The effects of refinery scale and composition of products produced on the overall profit and the selected process topology are investigated. The effect that the tipping fee of MSW has on the overall profitability of the process is investigated parametrically for several values. Complete material, energy, carbon, and greenhouse gas balances are additionally provided for each case study investigated. The results suggest that production of liquid fuels, olefins, and aromatics is profitable at the highest scales (i.e., 5 thousand barrels per day of liquid fuels and 500 metric tons per day of chemicals) investigated with superior environmental performance compared to petroleum-based processes.