A Thermodynamic Approach to the Integration of a Sugar Cane Bagasse Gasifier with a Solid Oxide Fuel Cell

Abstract

The thermo-conversion of liquid and solid biomass resources is becoming one of the best alternatives for waste solids reuse and green energy production, especially for developing countries. The proposed methodology allows the thermodynamic and electrochemical modeling of sugar cane bagasse gasification (B-G) coupled to a medium temperature solid oxide fuel cell stack. The validation of the models is carried out using pilot plant data for two biomass sources: sugar cane bagasse and rice peel. The synthesis gas composition, LHV and HHV are determined as well as the fuel cell power output and systems performance evaluated. After model validation the solid biomass gasification is studied for waste sugar cane bagasse, varying: the air factor (0.25-0.4) and air preheating (120 °C – 250 °C). The fuel cell utilization coefficient is fixed (FUC = 0.75), in this way the depleted gases from the stack can be used in an after combustor to produce energy for the B-G otherwise an overall efficiency penalty is superimposed to the system. The best results are obtained at 150 °C of preheating temperature and 0.30 excess of air in the gasifier at which the system efficiency is 74.3 %. The HHV (ranging from 2.82 MJ/kg to 4.08 MJ/kg) and LHV (2.66 MJ/kg to 3.84 MJ/kg) of the gasification gasses produced from sugar cane bagasse are similar to those reported for other biomass sources.