Thermodynamic, exergo-environmental, and thermoeconomic assessment of a high-capacity heat and power generation system with hydrogen production: A case study on municipal solid waste combustion, geothermal fluid utilization, parametric sensitivity analysis, and integrated CO₂ capture

This article presents a process for the concurrent creation of electricity, hydrogen, and heat through the integration of biomass and geothermal energy. This system exhibits superior thermodynamic efficiency relative to comparable research, as direct biomass combustion in a downstream Steam Rankine Cycle facilitates electricity generation. To regulate carbon dioxide emissions, the combustion gases undergo processing in a chemical absorption unit. Additionally, geothermal energy is employed to power the chemical absorption section, while surplus heat is directed to the Kalina cycle. The chemical absorption unit utilizes surplus heat for hot water generation, while the extra capacity of heat and electricity is allocated for hydrogen fabrication in a Proton Exchange Membrane electrolyzer. The proposed system is thoroughly investigated in terms of thermodynamics, exergo-environment, and thermoeconomics. A parametric study is conducted for parameters such as biomass flow rate, hydrogen production rate from the electrolyzer, and temperature of the turbine's inlet steam in the steam Rankine cycle. The steady state for this novel process can be generated by employing Aspen HYSYS software alongside the acid gas and Peng-Robinson equations. In the base case, the results show that the proposed system could manage to generate 12,810 kW of net electrical power, 16.13 kg/h of hydrogen, and 1848 kW of thermal power. Under these conditions, the thermal and exergy efficiencies are 50.7 % and 44.95 %, respectively, and the total specific exergy cost is 8.11$/GJ. Parametric study results reveal that increasing the steam temperature entering the T-100 turbine is an influential factor in increasing net electrical power production, improving thermodynamic efficiency, and enhancing energy-saving potential. Additionally, the vapour generator in the steam Rankine cycle exhibits the maximum exergy destruction rate of 9144 kW.