Currently, the production of alternative fuels from renewable sources such as biomass has been increased in order to meet energy policies and reduce the environmental impacts of fossil fuels. This work is focused on hydrogen production from oil palm empty fruit bunches using different biomass gasification methods (direct gasification, indirect gasification, and supercritical water gasification) and purification technologies (selexol-based absorption and pressure swing adsorption). Six routes were selected based on these technologies and simulated using Aspen Plus software. Possible operating process improvements were suggested based on parametric sensitivity analysis by studying the effect of several variables on hydrogen production: gasification temperature, gasifying agent-to-biomass ratio, steam-to-carbon monoxide ratio, temperature of a high-temperature step reactor, and pressure in a hydrogen purification unit. The methodology of waste reduction algorithm was performed to assess the environmental impacts of each route. Results showed that hydrogen production was improved by increasing the gasification reaction temperature to 900 °C, oxygen-to-biomass ratio to 1.5, and pressure of purification stage to 10 atm for all routes. However, routes 1 and 2 presented a slight increase up to 0.7% in hydrogen yield using 1.5 mol O2/mol biomass. The environmental assessment revealed that routes 3 and 4 exhibited the lowest toxicological and atmospheric environmental impacts because of the use of char generated in the gasification reaction for energy production. These results indicated that route 4 exhibited the best performance for producing hydrogen from an environmental viewpoint.
Copyright © 2019 American Chemical Society.