Integration of biomass gasification with a solid oxide fuel cell in a combined cooling, heating and power system: A thermodynamic and environmental analysis

Abstract

A biomass-fueled combined cooling, heating and power (CCHP) system is proposed and thermodynamically assessed. The system consists of a biomass gasifier (as the primary energy source), a solid oxide fuel cell (as the power generation unit), a double effect absorption refrigeration cycle (for cooling production) and a HRSG (for steam production for heating purposes). Taking into account the environmental considerations, energy and exergy analyses are conducted for the proposed system and its performance is compared with the corresponding power generation unit and the CHP system. Through a parametric study it is observed that the current density and fuel utilization factor play key roles on the system performance. In addition, considering the system as a combination of three subsystems, i.e. the SOFC, CHP system and CCHP system, an environmental impact assessment in terms of CO2 emission is conducted. Municipal solid waste is examined as biomass and it is observed that maximum exergy efficiency of the CCHP system is 37.92% with a CO2 emission of 20.37 t/MWh which shows an increase of 49.88% in exergy efficiency and 64.02% decrease in CO2 emission, compared to the solo SOFC system. It is concluded that the air heat exchanger and the gasifier are two major sources of irreversibility in the system and the exergy loss is considerable compared to after burners' exergy destruction.