Sustainable framework of hydrogen production from date palm waste with CO₂ capture: An energy, exergy and economic analysis

Date palm waste (DPW) is a rich agricultural waste product, mostly produced in the Middle East and North Africa (MENA) region, and is conventionally lost or used as a low-value material, e.g., as compost material, or incinerated. Nonetheless, they have a high level of organic content, and most of them are readily available, with strong potential of being used as renewable sources of sustainable energy. The study included the simulation approach to generate hydrogen production from DPW by steam gasification followed by two different CO₂ capture approaches. The Aspen Plus V14® software served to develop simulation models that incorporated a methanol-based CO₂ system for case 1 and calcium looping (CaL) systems for case 2 CO₂ capture processes. Syngas production through gasification takes place under equilibrium until the stream reaches water gas shift reactors (WGSR) for increased hydrogen generation. A comprehensive parametric assessment of gasifier operations involved multiple factors including temperature changes and biomass rates combined with steam volumes to study their influence on hydrogen production, carbon dioxide separation, and system performance measurements. The results in Case 2 surpassed those in Case 1 by obtaining higher hydrogen amounts and enhanced carbon dioxide capture performance with improved thermodynamic and exergy efficiency. Case 2 generated a higher production rate of 112.88 kg/h of hydrogen as well as 1215.03 kg/h of CO₂ removal compared to Case 1 which produced 111.25 kg/h of hydrogen at 876.29 kg/h CO₂ capture rate. The process and exergy efficiencies of Case 2 were superior to Case 1 (47 % and 57 % compared to 33 % and 46 %) and the utility requirement was also lower per unit of produced hydrogen. Case 1 has the CAPEX of 19.85 MM$ while Case 2 provided nearly 16.5 % savings in terms of CAPEX that amounted to 16.58 MM$. Considering the annualized capital and operation costs, the hydrogen production cost for Case 1 is calculated as $5.52/kg, while, Case 2 reflected the hydrogen production cost of $5.26/kg. Overall, case 2 has been found be a more cost-effective, efficient and environmentally preferable option for large-scale production of hydrogen from DPW.