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Abstract Biodegradable plastics, perceived as ‘environmentally friendly’ materials, may end up in natural environments. This impact is often overlooked in the literature due to a lack of assessment methods. This study develops an integrated life cycle impact assessment methodology to assess the climate-change and aquatic-ecotoxicity impacts of biodegradable microplastics in freshwater ecosystems. Our results reveal that highly biodegradable microplastics have lower aquatic ecotoxicity but higher greenhouse gas (GHG) emissions. The extent of burden shifting depends on microplastic size and density. Plastic biodegradation in natural environments can result in higher GHG emissions than biodegradation in engineered end of life (for example, anaerobic digestion), contributing substantially to the life cycle GHG emissions of biodegradable plastics (excluding the use phase). A sensitivity analysis identified critical biodegradation rates for different plastic sizes that result in maximum GHG emissions. This work advances understanding of the environmental impacts of biodegradable plastics, providing an approach for the assessment and design of future plastics.
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Towards the production of net-negative greenhouse gas emission bio-based plastics from 2nd and 3rd generation feedstocks
Here, we show production pathways for greenhouse gas (GHG)-negative bio-based plastics from 2nd and 3rd generation feedstocks. We focus on bio-based plastics that are technically capable of replacing 80% of the global plastic market. By presenting life cycle inventories and discussing GHG-emissions hotspots, this work will inform stakeholders along the plastic supply chain of the necessary steps to achieving net-zero emissions by 2050, and potentially, how to drive net-uptake. This work is of critical importance given the overwhelming mass of plastic produced annually and the resulting CO2 emissions. To conduct this assessment, we derive life cycle inventories for nine different bio-based plastics and address the impact of methodological choices, such as allocation method, on the resulting 100a global warming potential (GWP). Our findings show that resources used and processing methods implemented have significant effects on the potential for us to derive carbon-negative plastics. Furthermore, we find that environmental impact quantification methods greatly influence the perceived GWP of such processes. For example, economic and mass allocation methods resulted in an apparent increase in GWP of up to 39% and 166%, respectively, compared to no allocation for bio-based plastics made from 2nd generation crops, whereas mass allocation resulted in the lowest GWP for bio-based plastics made from 1st generation crops. In considering environmental impact hotspots, our findings show that decarbonization of thermal energy and electricity, reduced use of ammonia-based fertilizer, renewable hydrogen production, use of bio-based alternatives for petrochemicals and plasticizers, enzyme production pathways from 2nd generation crops, and more efficient biomass conversion processes to reduce feedstock inputs may be critical steps in creating GHG negative bio-based plastics in the future.
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- Award ID(s):
- 2143981
- PAR ID:
- 10517664
- Publisher / Repository:
- Elsevier
- Date Published:
- Journal Name:
- Journal of Cleaner Production
- Volume:
- 445
- Issue:
- C
- ISSN:
- 0959-6526
- Page Range / eLocation ID:
- 141203
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1016/j.jclepro.2024.141203
