Prospective Global Warming Potential of Australian Low-Emission Hydrogen in a Net-Zero Emission Context

Green hydrogen, produced from water electrolysis and renewable energy, will be crucial in decarbonising hard-to-abate sectors and industries where direct electrification is difficult. Australia has a unique opportunity to supply its abundant renewable energy potential to countries such as Germany or Japan. Net-zero emissions (NZE) scenarios suggest that the proton exchange membrane (PEM) type of water electrolysis technology will likely dominate. Although PEM electrolysis is a well-studied technology, its commercialisation and deployment are relatively new compared to the ambitious NZE scenario. Only a few studies have evaluated the global warming potential (GWP) of hydrogen produced in Australia, and these were at a relatively small scale or with limited life cycle inventory data. Also, most of the GWP of electrolytic hydrogen production originates from the electricity used. Yet, there is currently no comprehensive understanding of the influence of capacity factors for these sources on the produced hydrogen. Therefore, this study conducts a prospective life cycle assessment (pLCA) focusing on the GWP of a PEM electrolysis plant to account for the technological improvements and potential variations of GWP from the renewable energy source. Also, a GWP target limit for low-emission hydrogen in a 2°C NZE context is established to compare the pLCA results. In 2025, findings reveal that wind-based electrolysis is preferable to remain below the GWP target of ~1.67kgCO 2 eq/kgH 2. Solar-based systems can be implemented and remain in line with the GWP target as soon as 2025, provided a relatively high capacity factor. Beyond 2025 and by 2050, all renewable electricity mix would lead to electrolytic hydrogen production to remain below the GWP target with results ranging from 0.8-1.6kgCO 2 eq/kgH 2 . By analysing the GWP of Australian low-emission hydrogen in relation to capacity factors of renewable energy sources in a 2°C NZE context, this work contributes to Australia’s role in the future global hydrogen economy.