Thermo-economic analysis of a polygeneration system using biogas and waste tire based on the integration of solid oxide fuel cell, gas turbine, pyrolysis, and organic rankine cycle

Abstract

To optimize the biogas power generation process and waste tire disposal, a novel polygeneration system has been conceptualized. The hybrid design comprises a solid oxide fuel cell-gas turbine subsystem, tire pyrolysis reactor, organic Rankine cycle, and waste heat recovery subsystem. The biogas is first utilized by the solid oxide fuel cell and gas turbine for power generation. Subsequently, the high-temperature exhaust is utilized to preheat the fuel and oxidant and to heat the pyrolysis reactor and organic Rankine cycle, thereby improving the power generation and energy conversion efficiency. A comprehensive case study has been carried out to verify technological and economic feasibility of the proposed scheme. The results demonstrate that the net energy efficiency of the system is 70.11 % with an exergy efficiency of 69.65 %, and that the hybrid system maintains a high level of performance even when the fuel cell operating temperature varies. The irreversibility mainly arises from the pyrolysis reactor, cell stack, and combustion chamber. The new design requires only an initial investment of 722.93 k$ and can be recovered in 5.09 years with a net present value of 1795.51 k$ over its 25-year service life. Therefore, the proposed system is highly promising and suitable for implementation.