Performance Comparison on Biomass Gasification Reactor using Cocoa Pod Husk Waste for Hydrogen Production

Biomass is gaining recognition as a valuable renewable energy source due to its plentiful supply and relatively cheaper cost than other energy sources. One significant advantage of biomass is its ability to produce minimal carbon dioxide emissions during gasification. Gasification, which typically employs either downdraft fixed bed or bubbling fluidised bed gasifiers, is favoured for producing hydrogen gas, an essential element for energy production. This process can be represented using the Aspen Plus simulator, which is used for process simulation studies. Nevertheless, simulation research's predominant focus has been exclusively on coal gasification, with comparatively less attention given to biomass gasification. This study uses Aspen Plus software to examine the gasification processes of downdraft fixed-bed and bubbling fluidised bed reactors. Utilising cocoa pod husk as feedstock, both processes were analysed under the same operating conditions. The fluidised bed gasification process produced more hydrogen gas (7.62%) than the fixed-bed reactor (5.84%). A sensitivity analysis evaluated the influence of gasifier temperature and air-to-biomass ratio. It was found that the fixed-bed reactor produced more hydrogen (6.33%) at 760 °C, while the fluidised bed reactor yielded more hydrogen (8.43%) at 740 °C with an air-to-biomass ratio of 0.01. The study further discovered that a steam-to-biomass ratio of 0.15 in the fluidised bed reactor demonstrated the highest hydrogen yield, suggesting this as the optimal operating condition. The study offers vital knowledge on how to optimise biomass gasification operations to enhance the production of hydrogen.