Design and comparisons of three biomass based hydrogen generation systems with chemical looping process

• Three chemical looping systems are proposed for biomass based hydrogen generation.
• The CO2 discharge is minimized with the utilization of both CLG and CLP technologies.
• The cold gas efficiencies of Systems A, B and C are 72, 54 and 60%, respectively.
• The values of Rhtb of Systems A, B and C are 0.73, 0.66, and 0.76 Nm3/kg.
• The values of Rcs of Systems A, B and C are found to be 92, 95 and 96%.

The technology of hydrogen generation from biomass has attracted more and more attentions nowadays. In this work, three biomass-based chemical looping hydrogen generation systems, Systems A, B and C, are comprehensively studied. System A is mainly composed of biomass hydrogasification, methane reformation and the calcium-looping based CO2 absorption. System B is mainly composed of biomass steam gasification and Fe2O3/FeO-looping based hydrogen generation circulation. System C is mainly composed of biomass steam gasification and Fe3O4/FeO-looping based hydrogen generation circulation. The three systems are modeled and their characteristics are analyzed and compared thermodynamically. System A has the highest cold gas efficiency (CGE) which is 72%; System B has the lowest CGE of 54% but it can generate additional nitrogen as byproduct; System C has the highest hydrogen generation ratio and its CGE is moderate and is 60%. The carbon dioxide sequestration rates of the three systems are all above 90%.