Assessment of energy flows in integrated catalytic adsorption (ICA) steam gasification for hydrogen production

Biomass has a potential to produce sustainable and renewable hydrogen due to its low sulphur and nitrogen content (low NOx and SOx emissions) and contributes towards net CO2 cycle. Biomass steam gasification is found to be most promising among thermal conservation processes for renewable hydrogen production. The energy required for gasification using steam is high compared to other gasification agents e.g. air or pure oxygen. The integrated catalytic adsorption (ICA) utilizes catalyst and CO2 adsorbent together in the single fluidized bed gasifier. The present study investigates the energy flows to optimize the gasification energy requirement with respect to hydrogen concentration and yield in the ICA process at 600, 650 and 750 °C. The overall gasification energy required increased with increasing gasification temperature from 675 to 750 °C. However, a slight reduction in required energy was observed from 600 °C to 675 °C which might be due to strong CO2 adsorption, an exothermic reaction, and contributes to the energy requirements of the process. This was further verified with zero CO2 and highest hydrogen compositions (82 vol%) at 675 °C. However, ICA steam gasification is found to be a high energy consuming process and heat integration has to be considered for an economical hydrogen generation process