Modeling and Simulation of Syngas Potential From Supercritical Water Gasification of Combustible Municipal Solid Waste Materials

Abstract

Municipal solid waste (MSW) generation has threatened human health and the environment while being a renewable energy source for green energy transition. Traditional waste-to-energy technologies have shown their limits in terms of energy efficiency and pollution, whereas numerous studies were conducted on “supercritical water gasification (SCWG) technology to achieve a neutral carbon footprint. However, there is limited research and a lack of knowledge on SCWG of different combustible municipal solid waste (CMSW) materials. Hence, this study aimed to assess the gasification efficiencies and syngas potential from SCWG of different CMSW materials, composed of putrescible, miscellaneous combustible (MC), plastic, textile, and paper&cardboard, through modeling and simulation in Aspen Plus. The energy content and greenhouse gas (GHG) potential of predicted syngas composed of H₂, CH₄, CO, and CO₂ were assessed under optimal operating conditions obtained through sensitivity analysis. As a result, the temperature of 650°C, pressure of 22 MPa, and waste-to-water ratio of 1:5 were optimal conditions with temperature being the most influencing parameter on the gasification. Moreover, putrescible achieved the lowest gasification efficiency (GE), carbon gasification efficiency (CE), hydrogen gasification efficiency (HE), and energy recovery (ER) of 83.379%, 99.981%, 25.629%, and 8.657%, respectively, with the lowest high heating value (HHV) of 0.94 MJ/kg, low heating value (LHV) of 0.80 MJ/kg, and GHG potential of 0.002 kg CO₂ eq. The highest CE (100.013%) and ER (243.067%) were obtained from textile and paper&cardboard, respectively, while the highest GE (155.165%) and HE (140.213%) were obtained from plastic. Plastic showed the highest energy content, with an HHV of 42.98 MJ/kg and LHV of 38.30 MJ/kg, along with the highest GHG potential (15.788 kg CO₂ eq), attributed to its inherent high yields of H₂ and CH₄. Therefore, decision-makers could consider syngas recovery from SCWG of CMSW to mitigate environmental pollution and offset fossil fuel dependency.