Exergy analyses of an integrated solid oxide fuel cell and biomass gasification system

An integrated process of biomass gasification and solid oxide fuel cells (SOFC) is investigated using energy and exergy analyses. A performance comparison of power systems for different gasification agents is given by thermodynamic analyses. Exergy analysis is applied to investigate exergy destruction in components in the power systems. When using air or oxygen-enriched air as gasification agents, the gasifier reactor causes the greatest exergy destruction. For the case in which oxygen-enriched air as gasification agent, about 29% of the chemical energy of the biomass is converted into net electric power, while about 17% of it is used to for producing hot water for district heating purposes. The total exergy efficiency of combined heat and power is 29%.For the case in which steam as gasification agent, the highest exergy destruction lies in the air preheater due to the great temperature difference between the hot and cold side. The net electrical efficiency is about 40%. The energy combined heat and power efficiency is almost 36%, which is higher than that when air or oxygen-enriched air as gasification agent.