Life cycle assessment on alternative hydrogen production for greener technology

Hydrogen has been recognized as an alternative energy carrier and one of the future fuels in the global transition to clean energy. Hydrogen production with net-zero-carbon emissions has been developed because steam methane reforming, as a conventional means of hydrogen production, involves carbon dioxide emissions. This study carried out a life cycle impact assessment of conventional hydrogen production and compared the outcomes to two other zero-carbon emission technologies: proton exchange membrane electrolysis and methane pyrolysis. Main inventory data collection was based on process simulation and impact assessment using the Aspen plus V12.0 and Simapro 9.1 software packages, respectively. The system boundary involved gate-to-gate consideration with electricity supply from Thailand’s grid mix and a functional unit of 1,000 kg/h hydrogen production. The ReCiPe 2016 midpoint impact assessment method was used to evaluate five impact categories: global warming potential, freshwater and marine ecotoxicity, and human carcinogenic and non-carcinogenic toxicity. In terms of global warming potential, proton exchange membrane electrolysis was 1.7 times higher than steam methane reforming and 2.3 times higher than methane pyrolysis, since its primary energy is derived from fossil-based electricity. Although methane pyrolysis relied on hydrocarbon feedstock, it had the lowest environmental impact in all five impact categories investigated.