Achieving high-efficiency conversion and poly-generation of cooling, heating, and power based on biomass-fueled SOFC hybrid system: Performance assessment and multi-objective optimization

In order to develop clean and efficient energy conversion technology, a novel combined cooling, heating and power (CCHP) system using biomass as fuel is proposed in this work. The proposed CCHP system consists of biomass gasification unit, solid oxide fuel cell (SOFC), engine power generation unit and absorption refrigeration unit. Thermodynamic model of the CCHP system is developed for the parametric and exergy analyses to evaluate the performance. The parametric analysis shows that increasing the steam to biomass ratio or the SOFC fuel utilization factor helps to improve the electrical efficiency, while the increase of air equivalent ratio has a negative effect. The exergy analysis shows that the two units of biomass gasification and engine power generation have the largest exergy destruction ratio, which is 46.9% and 16.8% under the biomass flux of 500 kg.h- 1. This is because these two units involve in high-temperature thermochemical reaction process, resulting in relatively large exergy destruction. Besides, the tradeoff between maximum exergy efficiency, CCHP efficiency and minimum total annual cost is conducted by multi-objective optimization. Through optimization, the system could reach the high CCHP efficiency of 75% and net electrical efficiency of 52%, as well as the low total annual cost of 410 k$ simultaneously. This work could provide the basic design idea, and high-efficiency and low-cost operation strategy for the practical application of the proposed novel biomass-fueled CCHP poly-generation system.