Conversion of municipal solid waste to green energy: numerical studies

Greenhouse gas (GHG) emissions from the conventional management of municipal solid waste (MSW) are a serious environmental problem. Transformation of energy content present in MSW to combined heat and power (CHP) offers simultaneous advantages of reduction in GHG emission and pressure on finite fossil fuel reserve. Current research is devoted to developing a numerical model in Aspen Plus software to estimate the CHP generation potentiality of MSW and application to Bangladesh for the first time. CHP generation is accomplished through thermal treatment of gasification coupling with an internal combustion engine (ICE) system. Gasification model development is completed through calibration and validation. Model calibration is performed by comparing the experimental data on syngas generation from a blend of waste pulp (WP) and deinking sludge (DIS) in a pilot-scale fluidized bed reactor (FBR) whereas validation is by linking the outcomes on gasification of bamboo chips in an FBR at four different operating conditions. Sensitivity analysis identifies 850 °C and an equivalence ratio of 0.2 as the optimal conditions for air-gasification of MSW. The study estimates the CHP generation capacity of the analyzed MSW is 0.89 kWh/kg of dry solid (DS) MSW for electrical energy and 1.61 kWh/kg of DS for thermal energy. MSW in Bangladesh could generate approximately 3,300 GWh/yr of electricity and 6,000 GWh/yr of thermal energy in 2024. Electrical and thermal energy generation from MSW can reduce net annual GHG emissions of 2,510 Mt CO2/yr compared to similar quantities of CHP generation from fossil fuels. This ensures proper MSW management, greater GHG reduction, and some relief for Bangladesh’s energy crisis.