Ex-ante life-cycle assessment of biomass-derived hydrogen via fast pyrolysis and sorption enhanced steam reforming: Addressing scale-up uncertainties

Abstract

Biomass conversion through pyrolysis and sorption enhanced steam reforming (PY-SESR) is a novel alternative for producing hydrogen at bench scale. This study focused on addressing uncertainties linked to its industrial-scale implementation, comparing it to the process without CO₂ capture (PY-SR), and using steam methane reforming (SMR) as benchmark, which is currently the main hydrogen production route. Both PY-SESR and PY-SR scaled-up processes were simulated in Aspen Plus®, based on experimental bench-scale data. Life-cycle assessment based on process simulation-derived inventories showed that the PY-SESR alternative was the only one resulting in renewable hydrogen production according to the European Renewable Energy Directive (RED III) (3 kg_CO₂-eq kg⁻¹_H₂ threshold), attaining net negative emissions (−1.12 kg_CO₂-eq kg⁻¹_H₂). Nevertheless, its higher energy consumption, mainly driven by sorbent calcination and CO₂ pressurization for storage, led to higher environmental burdens with respect to other indicators. Considering fossil resource use, ozone depletion and freshwater eutrophication, PY-SR was found to outperform both PY-SESR and SMR, while SMR performed better in acidification and use of minerals and metals. Monte Carlo simulations and a sensitivity analysis showed that heat demand and electricity consumption highly contributed to PY-SR and PY-SESR variability, as a consequence of the limitations associated to early-stage process scale-up.