Inherent Safety Assessment of Indirect Gasification of Oil Palm Empty Fruit Bunches for Hydrogen Production and Purification by Pressure Swing Adsorption (PSA)

Oil palm empty fruit bunches (EFB) are lignocellulosic residues generated in large quantities by the palm oil industry and represent a potential biomass resource for renewable hydrogen production. This study evaluated the inherent safety of an indirect gasification process of empty fruit bunches (EFB) for hydrogen production, coupled with purification via pressure swing adsorption (PSA), using the Inherent Safety Index (ISI) methodology. The assessment considered critical operating variables, including temperature and pressure, and integrated chemical sub-indices (toxicity, flammability, chemical interaction, and corrosivity) with process sub-indices (inventory, temperature, pressure, equipment, and process structure). The analysis yielded a total ISI of 36, exceeding the reference value of 24 used in the original ISI framework and indicating an unfavorable inherent-safety profile under the evaluated conceptual design conditions. The main hazard drivers were the combined flammability, explosiveness, and toxicity contribution governed by CO; the high individual explosiveness of H2; the toxicity of SO2; the potential formation of explosive mixtures following air ingress; and the relatively large process inventory. The indirect gasification section, reaching a maximum verified temperature of 900 °C and a maximum operating pressure of 60 bar, governed the temperature and pressure sub-indices, respectively. These findings identify significant inherent-safety challenges that should be addressed during subsequent process development. In particular, inventory minimization, prevention of air ingress, and evaluation of less severe temperature and pressure conditions where technically feasible represent relevant priorities for inherently safer design before industrial-scale implementation.