Exergy and environmental assessments of a novel trigeneration system taking biomass and solar energy as co-feeds

Abstract

This paper presents an exergy and environmental analysis of a novel trigeneration system with biomass and solar energy coupling utilization. The novel trigeneration system mainly consists of a biomass gasifier, a solar collector, an internal combustion engine, an absorption unit and a liquid desiccant unit. The solar collector provides steam for biomass gasification process, and the product gas is fed into the internal combustion engine for generating electricity. The flue gas is utilized by the absorption unit for cooling production, and heat exchanger for domestic hot water successively. The jacket water is considered as the low heat resource for generating desiccant capacity. The exergy efficiency, exergy destruction and CO2 emissions are analyzed under different parameters. The results show that the total exergy efficiency of trigeneration system in the case study is determined to 19.21%, and the solar energy contributes to decrease the consumption of biomass. It is also found that the highest exergy destruction takes place in the gasifier, follow by internal combustion engine and gas/water heat exchanger. In addition, the introduction of biomass and solar energy alleviates the impact on environment, mainly reduces the CO2 emissions in kg/MWh; the CO2 emissions decrease evidently compared with separated generation system.