Optimizing hydrogen production through steam gasification of biodiesel-derived waste glycerol: A parametric approach

Abstract. The high dependence on fuels including biodiesel, which garnered attention as an alternative for sustainable fuel sources. Despite these benefits, biodiesel production generates glycerol as a by-product, leading to oversupply challenges and exacerbating greenhouse emissions, and this phenomenon results in an eager movement for cleaner energy transition from waste. The focus on mitigating climate change has led to global initiatives such as the transition of waste-to-hydrogen for alternative clean fuel, in achieving cleaner energy and sustainability objectives. In these studies, the utilization of excess waste glycerol for maximum hydrogen production potential through steam gasification has been emphasized, by altering the core gasification parameters. The experimental data obtained from previous experimental studies forms the basis for parametric studies by using Aspen HYSYS. To achieve optimum H2 yield, several parameters including steam-to-glycerol (S/G) ratio, temperature, and pressure were investigated and identified as key parameters influencing gas yield. Based on the simulation, the impact of the S/G ratio on hydrogen and carbon monoxide (CO) yields is explored, with an optimum ratio of 0.074 identified. Temperature studies indicate 680˚C as the optimal condition for the highest hydrogen production when (S/G) ratio is 0.5, while pressure parametric studies underscore the significance of maintaining low pressure for optimal gas yields. To maximize the overall hydrogen yield, the gasification process is optimized by setting the steam-to-biomass (S/G) ratio at 0.072 and maintaining a temperature of 800 ˚C under atmospheric conditions. This configuration results in the highest hydrogen production, reaching 0.57. Recommendations for experimental improvements are provided to align experimental and simulation data. The utilization of simulation methods enhances accuracy, and findings contribute to the broader goal of sustainable and efficient clean energy production from biomass gasification.