Optimization of syngas production and biochar utilization from municipal solid waste (MSW) via integrated pyrolysis-gasification for electricity generation

Municipal solid waste (MSW) presents an environmental challenge and an untapped energy resource. This study explores the integration of pyrolysis and gasification as a thermochemical conversion method to produce synthesis gas (syngas) from MSW, with the hypothesis that the recycling biochar from pyrolysis process due to its high fixed carbon content and catalytic properties, effectively reducing tar formation and enhancing syngas quality, optimize energy recovery and potentially emissions from the system. From Aspen Plus simulation, resulting the indication that the highest low heating value (LHV) of 11.892 MJ/Nm³ is achieved at S/M = 0.7 and 850 °C, with CO (19.808 %) and H₂ (73.042 %) as dominant components, CCE reaching 84.593 % and CGE 66.984 %. With optimization, the optimum conditions are at 934.135 °C and S/M ratio is 0.7. This condition produced H₂ concentration of 73.13 %, CO of 20.3 %, CH₄ of 4 % and CO₂ of 1.1 %, LHV reached 11.878 MJ/Nm³, CCE 85.20 % and CGE 68.50 %. For the LHV value, although lower than another LHV range in methane-rich syngas, this value aligns with the high hydrogen content and clean combustion characteristics of the syngas produced. The syngas is further analyzed using Diesel-RK to simulate its conversion into electricity and produced final power output of 7.109 MW, mechanical efficiency of 90.4 %, NO₂ emission 25.545 g/kWh and 7.114 MW, mechanical efficiency 90.4 % after optimization, and lower NO₂ emission at 25.534 g/kWh. This research presents a viable waste-to-energy solution, contributing to sustainable energy production and waste management strategies. However, further research is needed to determine the economic feasibility, industrial scale, and regulatory feasibility.