Thermodynamic and economic analysis of a conceptual system combining medical waste plasma gasification, SOFC, sludge gasification, supercritical CO2 cycle, and desalination

Abstract

In order to improve the utilization of energy in solid waste, we propose a coupled system consisting of medical waste plasma gasification, solid oxide fuel cell (SOFC), sewage sludge gasification (SSG), supercritical carbon dioxide cycle (S–CO2) and multi-stage flash (MSF) desalination. The medical waste is plasma gasification and purified to produce clean syngas, which is used by the SOFC to generate electricity. the exhaust from the SOFC is mixed with crude gas from the sludge gasification to fully combust and release chemical energy while increasing the exhaust temperature. Finally, the high-temperature energy enters the waste heat utilization system consisting of S–CO2 and seawater desalination to be fully utilized. A thermodynamic and economic analysis of the proposed system shows that the hybrid system has a net power generation efficiency of 41.66%, an energy utilization efficiency of 64.95%, and an exergy efficiency of 41.25%. The plasma gasifier and SOFC are the main sources of exergy loss, accounting for 62.45% of the total destroyed exergy. The DPP of the project is only 4.4 years over a 20-year operating cycle, with an NPV of 117,652.81k$. This study demonstrates the advantages and benefits of the project in terms of solid waste resource utilization.