Conceptual waste-to-energy design incorporating plastic pyrolysis and anaerobic digestion: Thermodynamics, economics, and uncertainty analyses

To efficiently convert plastic and animal manure into energy, a novel waste-to-energy system integrating pyrolysis and anaerobic digestion has been proposed. In this system, plastic undergoes pyrolysis, yielding pyrolysis oil, char, and gas. The oil and char are marketed as products, while the pyrolysis gas and biogas from anaerobic digestion are combusted in a chamber to generate electricity via a gas turbine. The turbine's exhaust heat is utilized for plastic pyrolysis and as a heat source for an organic Rankine cycle to produce additional electricity. The residual low-temperature flue gas provides thermal insulation for the anaerobic digestion process. System feasibility was assessed through modeling and simulation, with thermodynamic and economic performance evaluations addressing key uncertainties. The design demonstrated an energy efficiency of 64.54 % and an exergy efficiency of 63.58 %, achieving a dynamic payback period of 3.88 years and a net present value of 73,524.79 k$. This integrated method improves energy conversion efficiency and economic feasibility, providing a sustainable solution for waste management and energy generation.