Conversion of municipal solid waste to hydrogen and its storage to methanol

Abstract

Municipal solid waste (MSW) has become a challenging issue for many decades, especially in developing countries, leading to several social and environmental problems. Appropriate treatment and conversion of this MSW are urgently demanded. In this study, an efficient conversion of MSW to methanol is proposed and analyzed. The developed system consists of simultaneous processes, integrating hydrothermal treatment (HTT), direct chemical looping, methanol synthesis, and combined cycle for power generation. HTT is conducted to increase the carbon content and caloric value of the MSW, as well as to physically uniform the material. The treated MSW flows to direct chemical looping for conversion to hydrogen while separating CO2. The produced hydrogen and CO2 are then used as feeds for methanol synthesis. Finally, the heat involved in the system is recovered by gas and steam turbines for power generation. Several operating parameters are analyzed in terms of total energy efficiency and methanol production, including chemical looping pressure, methanol synthesis temperature, and pressure. As general result, the proposed system shows high energy efficiency and methanol production. The highest total energy efficiency which can be obtained is 45.4%, under the conditions of chemical looping pressure of 4.0 MPa, and methanol synthesis temperature and pressure of 200 °C and 5.0 MPa, respectively. The integrated system can produce 41 kg/h methanol from 100 kg/h MSW, and it can independently cover the electricity required throughout the whole system.