Simulation and exergoeconomic analysis of the syngas and biodiesel production process from spent coffee grounds

The integrated production of biofuels from agro-industrial wastes is increasing around the world. The thermodynamic performance and economic analysis of these processes have become topics of interest given the need to reduce the cost of biofuels and their impact on the environment. This study develops a simulation of the production process of syngas and biodiesel from spent coffee grounds, and an exergoeconomic analysis that mainly determines the exergy destruction rate, the investment and operational cost rate, and the exergy destruction cost rate at component level and for the overall system. The total investment cost for the integrated process resulted in 13.2 million dollars. The specific cost of syngas and biodiesel from spent coffee grounds were estimated in $0.36/kg and $0.71/kg, respectively. The results show that the drying process including the air heating for the pretreatment of the biomass had an exergy destruction rate of 11,463 kW and was responsible of the 92% of the overall exergy destruction cost rate. An increment of the dead state temperature reduced the specific cost of syngas and biodiesel in 17% and 8%, respectively. Future studies should focus on the exergoeconomic optimization of the drying process of biomass in order to minimize the operational costs.