Exploring hydrogen production from plastic waste for urban transportation in Hong Kong and its environmental impact mitigation: integrating dynamic material flow analysis and life cycle assessment

Plastic waste to hydrogen technology offers a sustainable clean energy pathway while reducing landfill and incineration burdens. However, its feasibility as a feedstock for urban mobility decarbonization at the city scale remains largely unexplored. Hong Kong, as a densely populated metropolitan region facing substantial plastic waste challenges, presents an ideal case study to assess the viability of plastic-derived hydrogen for transportation applications. This study developed an innovative waste-to-wheel framework to assess the mitigation of environmental impacts on Hong Kong's urban mobility through plastic waste-to-hydrogen technology. Dynamic material flow analysis was used to quantify historical and future plastic waste generation, while life cycle assessment (LCA) was adopted to assess the environmental impacts associated with urban transportation in Hong Kong. The results indicated that accumulated plastic waste in Hong Kong is projected to reach 27.6 million tonnes (Mt) between 2026 and 2050, with polypropylene and polyethylene comprising 58.7% of the total, providing substantial feedstock for hydrogen production. Hydrogen demand in the transportation sector is estimated at 880.1 thousand tonnes of coal equivalent (tce) by 2050 under the hydrogen scenario. LCA results revealed that waste-based hydrogen production achieves the lowest global warming potential at −1.36 kg carbon dioxide equivalent (CO 2 -eq) per kg hydrogen, reducing transportation sector emissions to 193 thousand tonnes CO 2 -eq by 2050, which is 78.2% lower than the business-as-usual scenario. Plastic-derived hydrogen could supply 101.7% (97.5%-105.4%) of cumulative transportation hydrogen demand during 2026-2050. These findings validate plastic waste as a sustainable transportation fuel, guiding Hong Kong's hydrogen and circular economy planning.