Circular tyres and other developments in chemical recycling

2020 was an important year for technologies that break down waste plastic into small chemical building blocks ready for recycling to new plastics.  The industry ramped up its investment in these processes, in response to the increasing demand for high quality, food safe, recycled plastic.  But a report from the Global Initiative for Incinerator Alternatives (GAIA) concluded that chemical recycling is not a sustainable form of plastic waste management. 

On the industry side, more petrochemicals companies launched pilot projects in 2020. A wider range of polymers with ‘circular’ content is being commercialised. Chemically recycled polystyrene will be available from INEOS. Circular PVC can be purchased from Vynova and tyres with recycled content will be on the market in the near future. More companies also gained independent validation of their processes via ISCC PLUS and other certifications.

But industry and NGOs disagree fundamentally on the carbon foot print analysis of chemical recycling. In December, Cefic, (The European Chemical Industry Council), published an independent analysis showing that chemical recycling of mixed plastic waste saves greenhouse gas emissions compared with incineration. The GAIA analysis uses selective life cycle arguments to claim that chemical recycling is little more than incineration by another name.

This is because the two sides are comparing different parts of the lifecycle. The first part of the pyrolysis route to chemical recycling does have a higher carbon footprint than that of virgin plastic production, which is the focus of the GAIA report. However, when the whole lifecycle is taken into account, the avoided emissions of waste plastic incineration more than make up for this deficit, leaving chemical recycling with a lower carbon footprint than that of virgin plastic: hence the conclusion of the Cefic Report. 

It is important therefore to consider the complete lifecycle when comparing carbon footprints rather than cherry picking the parts that suit one particular argument. Getting this point accepted will be crucial to the approval of chemical recycling. EU technical experts advising the European Commission have already indicated that recognition of chemical recycling for Green Deal finance will be subject to a demonstrated greenhouse gas saving.

Part of the consideration of the lifecycle of plastic is understanding and accepting that mechanical recycling cannot be considered as an end-of-life option for common polymers such as polyethylene and polypropylene.  It is a low energy way of extending the use phase, but after a few cycles these plastics become too degraded for anything but incineration. NGOs do not really have an answer to this point and they fall back on the argument that we should substitute other materials for plastic, opening the door to different environmental risks.

The GAIA Report makes an additional point about impurities. But this also is lacking the necessary life cycle context. Waste plastic contains a range of polymers, pigments and treatment agents, resulting in contaminants that have to be removed in a separate processing step during chemical recycling. It is also possible that additional toxic contaminants are generated within the process itself. This would add to the complexity of the purification step. But again, a careful comparison with plastic incineration, which also produces toxic byproducts, is needed.

But coming back to the main driver for chemical recycling, one thing that didn’t change in 2020 was the European Food Safety Authority’s (EFSA) view on the suitability of recyclate for food contact. Chemical recyclate is already accepted for food packaging whereas most mechanical recyclate is still not approved, for hygiene reasons (apart from PET bottles). 

So 2020 saw the recycling of 2019’s old arguments on what to do with waste plastic, but the reality stayed the same. Plastics have marvellous properties for durable and single use goods, but both mechanical and chemical recycling will be needed to make them circular. 

Published: 25 January 21

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