Machine learning facilitated the modeling of plastics hydrothermal pretreatment toward constructing an on-ship marine litter-to-methanol plant

Abstract

An onboard facility shows promise in efficiently converting floating plastics into valuable products, such as methanol, negating the need for regional transport and land-based treatment. Gasification presents an effective means of processing plastics, requiring their transformation into gasification-compatible feedstock, such as hydrochar. This study explores hydrochar composition modeling, utilizing advanced algorithms and rigorous analyses to unravel the intricacies of elemental composition ratios, identify influential factors, and optimize hydrochar production processes. The investigation begins with decision tree modeling, which successfully captures relationships but encounters overfitting challenges. Nevertheless, the decision tree vote analysis, particularly for the H/C ratio, yielding an impressive R² of 0.9376. Moreover, the research delves into the economic feasibility of the marine plastics-to-methanol process. Varying payback periods, driven by fluctuating methanol prices observed over a decade (ranging from 3.3 to 7 yr for hydrochar production plants), are revealed. Onboard factories emerge as resilient solutions, capitalizing on marine natural gas resources while striving for near-net-zero emissions. This comprehensive study advances our understanding of hydrochar composition and offers insights into the economic potential of environmentally sustainable marine plastics-to-methanol processes.

Graphical abstract

Keywords

marine plastics / hydrothermal / methanol / machine learning / techno-economic assessment

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Competing interests

The authors declare that they have no competing interests.

Acknowledgements

The authors are grateful for financial support from the Marie Skłodowska Curie Actions Fellowships by The European Research Executive Agency, Belguim (Grant Nos. H2020-MSCA-IF-2020 and 101025906). More importantly, Dr. Yi Cheng acknowledge Dr. Fanhua Kong from the Petrochemical Research Institute of PetroChina Co., Ltd., China, who proposed the initial assumption of the system and years of guidance in the industrial syngas research area.

Electronic Supplementary Material

Supplementary material is available in the online version of this article at https://doi.org/10.1007/s11705-024-2468-3 and is accessible for authorized users.

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