Thermo-enviro-economic analysis of a novel landfill gas-fueled CCHP-desalination process combined with a liquefied natural gas cold energy recovery unit

This paper proposes utilizing landfill gas, obtained from landfilling activities, as a viable substitute for fossil fuels. In this study, an innovative heat design process for a landfill gas-fueled power plant is employed, representing a novel contribution to system development. The innovative cascade heat recovery process utilized in this method facilitates an eco-friendly multigeneration practice, resulting in reduced thermodynamic irreversibility and air pollution as well as an increase in the capacity of main products. Hence, the entire system consists of a bio power plant, a transcritical CO2 cycle, a low-pressure steam generation unit, a refrigeration cycle, a multi-effect desalination, and a liquefied natural gas cold utilization unit. The simulation is conducted by the Aspen HYSYS software, examining various aspects such as energy, exergy, economics, and environment. The results indicate that the energy and exergy efficiencies of the process are 79.96% and 32.93%, respectively. Moreover, the cost per unit exergy and specific CO2 emissions amount to 87.16 $/GJ and 0.2732 kg/kWh, respectively. Besides, a parametric study is performed based on the gas turbine's outlet pressure, the flue gas temperature leaving the transcritical CO2 cycle and multi-effect desalination, and the liquefied natural gas flow rate. Obtained results demonstrate that the specific CO2 emissions and cost per unit exergy face an increase with increasing the gas turbine's outlet pressure. Moreover, the increase in the flue gas temperature leaving the transcritical CO2 cycle exhibits a reduction in the CO2 emissions and an escalation in the cost per unit exergy.