A novel methanol-electricity cogeneration system based on the integration of water electrolysis and plasma waste gasification

Abstract

A new methanol-electricity cogeneration system consisting of plasma gasification, alkaline water electrolysis, methanol synthesis and supercritical CO2 cycle was designed to achieve near zero emission resource utilization of medical waste. The newly designed methanol-electricity cogeneration system uses synthesis gas converted from medical waste by plasma gasification and hydrogen obtained by water electrolysis for methanol synthesis. It uses a supercritical CO2 cycle to improve its performance. In addition, the waste heat carried by each flow unit in the process is used to provide domestic hot water for residents. Based on a model built with Aspen Plus and Matlab software, the system's advantages are examined in terms of thermodynamics and economics, and the effects of the main parameters are studied using a 4.00 kg/s plasma gasifier as an example. The results show that the system can achieve a methanol yield of 6.32 kg/s, an energy efficiency of 67.42%, and an exergy efficiency of 68.60%. The main source of irreversibility can be traced to three components, the gasifier, the electrolyzer, and the methanol reactor, which account for 75.31% of the total exergy destruction. It only takes 3.53 years to recover the initial investment in the proposed system, and over a 20-year lifetime, the waste-to-energy project yields a net present value of 355,318.47 k$.