Comparing carbon-saving potential of the pyrolysis of non-recycled municipal plastic waste: Influences of system scales and end products

Bauyrzhan Biakhmetov, Yue Li, Qunshan Zhao, Yong Sik Ok, Abay Dostiyarov, Young Kwon Park, David Flynn, Siming You

    Research output: Contribution to journalArticlepeer-review

    1 Citation (Scopus)

    Abstract

    Pyrolysis of non-recycled municipal plastic waste has the potential to mitigate the plastic waste crisis and to produce transport fuels (diesel or hydrogen), as compared with the conventional methods such as incineration or landfilling that have potential adverse environmental consequences. Transport fuel production from non-recycled municipal plastic waste contributes to the transition to more sustainable waste management. However, little is known about the influences of system scales and end product selection on the carbon footprints of the plastic waste treatment. Here, we applied the approach of life cycle assessment to compare the carbon-saving potential of centralized, large-scale and decentralized, small-scale pyrolysis systems producing diesel and hydrogen in the United Kingdom. It is shown that centralized systems had a lower global warming potential results than decentralized systems despite their greater transportation distances. The global warming potentials of diesel production for centralized and decentralized systems were 801 and 1345 kg CO2-eq. per tonne of non-recycled municipal plastic waste, respectively, whilst hydrogen production had much higher global warming potentials which are 7110 and 7990 kg CO2-eq per tonne of non-recycled municipal plastic waste, respectively. In hydrogen-producing systems, crude carbon nanotubes are also produced, and the purification process of carbon nanotubes requires significant material resource (hydrochloric acid and deionized water) inputs, resulting in high Scope 2 and 3 emissions. Also, it is worth noting that the global warming potential related to the Scope 1 emissions for the diesel-producing systems exceeds 80%, whereas the hydrogen-producing systems yield opposite results. The end use of diesel produced has a greater carbon footprint than the end use of hydrogen. The carbon saving from the displacement of fossil hydrogen was two times higher than that from diesel displacement. Decentralized, small-scale hydrogen production from plastic waste had the highest global warming potential among all as the conversion process of municipal plastic waste to hydrogen and carbon nanotubes for small-scale systems is more energy and resource intensive. Sensitivity analysis showed that various factors, such as feedstock composition and the heating energy consumption in the conversion process, had less influence on the global warming potential of centralized systems as compared to decentralized systems.

    Original languageEnglish
    Article number143140
    JournalJournal of Cleaner Production
    Volume469
    DOIs
    Publication statusPublished - 2024 Sept 1

    Bibliographical note

    Publisher Copyright:
    © 2024 The Authors

    Keywords

    • Carbon neutrality
    • Catalysts
    • Climate change
    • Diesel
    • Hydrogen
    • Net zero
    • Sustainable waste management

    ASJC Scopus subject areas

    • Renewable Energy, Sustainability and the Environment
    • General Environmental Science
    • Strategy and Management
    • Industrial and Manufacturing Engineering

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