Managing plastic waste - not all options are equal

A new study published by the European Commission’s Joint Research Centre (JRC) has attempted to compare and assess the current management options for plastic waste based on a number of scenarios.
The analysis sought both to qualify the criteria and conditions which should be considered to identify the most effective plastic waste management options, from a life cycle perspective, and to quantify the potential environmental impacts and life cycle costs of chemical or physical plastic waste recycling compared to energy recovery and/or mechanical recycling. The analysts also looked at the technical and environmental aspects involved in each technology, taking into account such factors as safety and the impacts of the polymer separation or breakdown method used. As well, they studied the key conditions under which chemical or physical recycling can be considered economically viable options.
The result is a comprehensive overview of the advantages and limitations of mechanical, physical and chemical recycling, and energy recovery which the report discusses in the light of three main criteria.
These were:

• the maximisation of material recovery, while minimising processing impacts, principally related to energy consumption;
• the specificity of the plastic waste stream and the treatment required;
• and the economic feasibility of each management option.

The report is an important one, as the European Union is still undecided about the status of recycling methods other than mechanical technologies, while at the same time setting ambitious targets for recycling and the use of recycled content. As the target dates come closer, it has become clear that these will not be achieved with mechanical recycling alone. Hence a report like this one, with its highly detailed study of the various scenarios, can make a substantial contribution to the discussion.
In terms of environmental impacts, especial attention was paid to the specific effects of climate change, particulate matter, acidification, and resource use, fossils in the scenarios presented for mechanical recycling, physical recycling, chemical recycling, and energy recovery. Amongst others, the analysts found that in so far as climate change was concerned, ‘all in all, any scenario (technology or combination of technologies) leading to combustion of the waste is less preferable to alternative mechanical, physical or chemical recycling, notwithstanding the recovery of electricity and heat, incurring environmental saving. The environmental savings associated with energy recovery from waste are indeed not enough to compensate for the environmental burdens associated with the combustion of the fossil carbon in the plastic waste and subsequent fossil CO2 emissions’.
Likewise, mechanical, physical and chemical recycling were preferable to energy recovery, across all the waste streams investigated, when it came to climate change effects.

Where the other environmental impact categories were concerned, when mechanical and physical or chemical recycling could be directly compared (i.e., the same input-waste was treated), no clear ranking of the scenarios involving these technologies could be derived ‘as one performed better in some impact categories and worse in others’.
To assess the economic viability of physical and chemical recycling, five pathways were analysed - dissolution, glycolysis, methanolysis, pyrolysis and gasification - in the light of a number of determinants, including feedstock prices, capital and operational expenditures and output prices.
Under current conditions, methanolysis, pyrolysis and gasification were determined to have negative net incomes, which meant that across all the scenarios analysed, they were not economically viable. Dissolution and glycolysis showed more positive results. The report’s authors add that due to the limitations of the data on which the analysis is based, these should not be regarded as a definite conclusion, but as a preliminary exploration. In their view, conditions can be created under which some or all of the chemical recycling technologies could become economically viable. As they point out, ‘physical and chemical recycling technologies are still under heavy development’. When the costs come down in the future their economic performance will increase.
“Using projections of technical advances in chemical recycling technologies and increased costs of virgin production, we estimate whether and when different chemical recycling technologies would become economically viable before 2040. Based on these scenarios, all chemical recycling pathways except gasification would be expected to achieve positive net incomes within the next two decades.”
The report concludes with a number of recommendations. As well, it comments on the importance of weighing the choice of management option for plastic waste based on the three main criteria referred to above. In particular, regarding the specificity of the plastic waste stream and the treatment required, they stress the importance of factoring in the composition and the quality of the waste when comparing management options.
“Plastic waste is a heterogeneous and challenging flow, and the composition/quality is a determining factor for the operations to be undertaken.,” they write. “Improved information on the waste-feedstock composition is crucial also to understand in which cases chemical recycling and mechanical recycling may end up competing for similar waste feedstock or in which cases chemical could really be integrated with mechanical recycling.”