This work presents a techno-economic assessment of hydrogen production via sorption-enhanced gasification (SEG) of hazelnut shells across three plant scales (100 kWth, 1 MWth, and 10 MWth). The overall model is developed through the integration of Aspen Plus^® process simulation, coupled with MATLAB^®-based kinetic reactor modelling, enabling the assessment of the entire process chain. The kinetic SEG model, validated against experimental literature data, was implemented to describe the fluidized bed gasifier behaviour at the three scales. The resulting process streams were subsequently integrated into Aspen Plus^® for downstream upgrading and overall system analysis. The simulations show that the SEG process produces a hydrogen-rich syngas with H₂ contents around 80 vol.%_dry-basis, which is further upgraded to a hydrogen purity of 99.95% with a recovery of 90% via pressure swing adsorption. The process exhibits stable performance across scales, with Cold Gas Efficiency values around 60% and hydrogen yields close to 1 Nm³/kg_Biomass. The economic analysis highlights a decrease in the Levelized Cost of Hydrogen (LCOH) from 41.3 €/kg at 100 kWth to 6.8 €/kg at 10 MWth. These results indicate that SEG represents a promising pathway for low-carbon hydrogen production, while enabling the valorisation of biogenic residues within a sustainable energy framework.