Carbon footprint of plastic from biomass and recycled feedstock: Methodological insights

Purpose: A circular (bio)economy is sustained through use of secondary raw material and biomass feedstock. In life cycle assessment (LCA), the approach applied to address the impact of these feedstocks is often unclear, both in respect to the handling of the recycled content and end-of-life recyclability and disposal. Further, the modelling approach adopted to account for land use change (LUC) and biogenic carbon effects is crucial to defining the impact of bio-based commodities on Global Warming. Method: We depart from state-of-the-art approaches proposed in recent literature and apply them to the case of non-biodegradable plastic products manufactured from alternative feedstock, focusing on selected polymers that can be made entirely from secondary raw material or biomass. We focus on Global Warming and on the differences incurred by recycled content, recyclability, LUC, and carbon dynamics (delayed emission of fossil C and storage of biogenic C). To address the recycled content and recyclability, three formulations recently proposed are compared and discussed. LUCs are addressed by applying and comparing a biophysical, global equilibrium and a normative-based approach. Temporary storage of biogenic carbon is handled applying methods for dynamic accounting. These methods are applied to two case studies (rigid plastic for packaging and automotive applications) involving eight polymers. Results and discussion: Drawing upon the results, secondary raw material is the feedstock with the lowest Global Warming impact overall. The results for biobased polymers, while promising in some cases (polybutylene succinate) are significantly affected by the formulations proposed to handle the recycled content and recyclability. We observe that some of the proposed formulations in their current form do not fully capture the effects associated with the biogenic nature of the material when this undergoes recycling and substitutes fossil materials. Furthermore, the way in which the recycled content is modelled is important for wastes already in-use. LUC factors derived with models providing a combined direct and indirect impact contribute with 10-15% of the burden, which is comparable to the savings from temporary storage of biogenic carbon, when included. Conclusion: End-of-life formulations can be improved by addition of corrective terms accounting for the relative difference in disposal impacts between the recycled and market-substituted product. This affects the assessment of biobased materials. Inclusion of LUCs effects though economic/biophysical models in addition to (direct) LUC embedded in datasets may result in double-counting and should be done carefully. Dynamic assessments allow for detailed modelling of carbon cycle, providing useful insights on the impact associated with biogenic C storage.

TONINI Davide;  SCHRIJVERS Dieuwertje;  NESSI Simone;  GARCIA-GUTIERREZ Pelayo;  GIUNTOLI Jacopo; 

2021-04-15

SPRINGER HEIDELBERG

JRC122494

0948-3349 (online),   

https://link.springer.com/article/10.1007%2Fs11367-020-01853-2,    https://publications.jrc.ec.europa.eu/repository/handle/JRC122494,   

10.1007/s11367-020-01853-2 (online),