Techno-economic assessment of a conceptual waste-to-energy CHP system combining plasma gasification, SOFC, gas turbine and supercritical CO2 cycle

In this paper, a novel scheme consisting of plasma gasifier, solid oxide fuel cells (SOFC), gas turbine (GT), and supercritical CO2 cycle has been developed for power and heat cogeneration. Fed by syngas converted from medical waste through plasma gasification, the new design is a SOFC-GT hybrid system benefiting from super-critical CO2 cycle to enhance its performance. Besides, the waste heat carried by the low-temperature exhaust gasses and CO2 stream is further exploited for providing domestic hot water to residents. The benefits of the suggested system were examined based on a 3 t/h plasma gasifier in the thermodynamic and economic aspects, and the effects of the main parameters were also investigated. It is found that the net power output of the studied system could reach up to 14.02 MW with a net waste-to-electricity efficiency of 59.30% and an exergy efficiency of 57.56%. The main source of irreversibility can be traced to three components, gasifier, cell stacks, and afterburner, accounting for 62.45% of the total exergy destruction. Only 3.77 years is required to recover the initial investment of the proposed system and a net present value of 109815.39 k$ can be attained by the waste-to-energy project during its 20-year lifespan.