Solar to sustainability (S2S): a comparative life cycle assessment of hydrogen production with a focus on a photoelectrochemical anion exchange membrane reactor

Abstract

This study employs a comparative life cycle assessment to provide data-driven insights into hydrogen production methods, uncovering the environmental impact of steam methane reforming (SMR), wind proton exchange membrane water electrolysis (PEMWE), solar PV PEMWE, photoelectrochemical (PEC) PEM reactors and PEC anion exchange membrane (AEM) reactors. The assessment employs a cradle-to-gate approach using SimaPro as the LCA software, with data from the ecoinvent database (i.e. v3.8) and published literature. Notably, 1 kg of hydrogen produced is considered a functional unit. Key environmental impacts, including global warming potential, ozone depletion, eutrophication, acidification and water use, are evaluated using the ReCiPe 2016 Midpoint method (H). The results demonstrate that hydrogen production through the PEC AEM reactor has the lowest environmental impact compared to other methods. The PEC AEM reactor shows the lowest global warming potential of 1.17 kg CO₂ eq per kg H₂ in the comparative LCA study. The highest human carcinogenic toxicity potential (HCTP) of 1.5 kg 1,4 DCB-eq per kg H₂ was obtained for the PEC PEM reactor. Wind PEMWE has the highest mineral resource scarcity (MRS) of 0.0839 kg Cu-eq per kg H₂ produced as the mining, processing and manufacturing of permanent magnets for wind turbines involve rare earth elements. SMR has the highest value of land use (0.189 m²a crop-eq per kg H₂) due to the large scale facility and infrastructure required in the SMR process. Moreover, a sensitivity analysis is conducted to assess the effect of regional energy supply on the global warming potential (GWP) associated with various hydrogen production methods. This study offers valuable insights highlighting the significance of considering various environmental impacts to facilitate informed decision-making for sustainable design.