PLASTICS IN A GLOBAL CIRCULAR ECONOMY?

A key question when considering how to manage plastic waste is whether there is a role for plastic in a global circular economy. Can it be treated like paper, glass, and metal to be recycled and reprocessed in an endless material cycle through the economy? The assessment of plastic recycling limitations in this report suggests that this may not be possible without major changes to production methods and production levels of plastic.

The concept of a circular economy where material resources are constantly cycled through a value chain of production, use, and recycling in order to maximize their utility and avoid the extraction and use of virgin materials, is a progressive antidote to a linear economy. In the classic linear economy, material resources are extracted from the environment, refined and processed into products which are used, and then become waste. As waste, they are disposed of—buried or burned and lost forever—removed from the inventory of resources that are available to produce new. Worse still, the impacts of burying or burning those resources are air, soil, and water pollution, human exposure to toxic wastes and emissions, and longterm impacts on biodiversity and climate.

 Converting to a truly circular economy means that those businesses whose activities align with a circular framework will likely benefit from the changes, while those entrenched in the old linear model will find it harder and less profitable to operate. This has led to many ‘linear’ economic interests attempting to redefine the concept of a circular economy to include themselves as an essential element of the circular economic system. This is often seen with incineration proponents who brand the burning of wastes and especially plastic waste as ‘energy recovery’ or ‘thermal recycling’. However, the burning of plastic waste not only generates toxic atmospheric and solid waste, it destroys the resource itself. In this case, the resources destroyed are the petrochemicals that were extracted to make the plastic and the ‘embedded energy’ in the plastic item. The embedded energy includes the energy to extract the oil, refine the petrochemicals, and manufacture the polymer, as well as transportation between all steps, including transport to market. All of that embedded energy is destroyed in a couple of seconds in the combustion chamber of the incinerator to extract the tiny amount of ‘calorific energy’ that is produced when the plastic object is combusted.

As many industries have come to realize they belong to the old linear economy and will lose ground in a circular economy, they and their industry associations have sought to distort its definition and seek inclusion. This has led to a proliferation of definitions and interpretations of the circular economy. The Centre for European Policy Studies has identified at least 12 academic and institutional definitions (CEPS 2017) of a circular economy and a brief internet search will double that. At the core of the circular economy concept as it is broadly understood is the avoidance of resource extraction through maximization of reuse and recycling of existing material resources and minimization of waste for the benefit of society and the environment.

It should also be recognized that there are some things in our economy and society that we do not want to recycle, including highly toxic materials. This is recognized in the Stockholm Convention and its general prohibition on recycling POPs waste. For plastics this means that it is necessary to avoid adding toxic additives to polymers that make recycling harder, contaminate the environment, and expose workers and consumers to harm. This is almost the opposite of where plastics production is currently headed, with a booming toxic additives market, designs that prevent recycling, and exponential growth in the production of single use polymers.

The proposed industry solution of chemical recycling is largely predicated on the basis that it can separate contaminants from plastic waste, allowing near virgin quality polymers to be recovered. This does not answer the question of how to deal with all the toxic, contaminated material separated from the ‘clean’ polymer. It also fails to deal with the fact that those newly recycled polymers will be formulated with more toxic additives before they become products again. Conversion of plastic to liquid fuels will see the toxic contaminants shifted to the atmosphere as emissions when the fuels are burned. Depolymerization will see toxics additives removed to become a vast reservoir of hazardous sludge residue. Pyrolysis of plastic waste for hydrogen will see a rapid increase in dioxin in solid waste residues of the process, and so it goes on. The toxic waste and emissions from these processes continue to reflect a linear economic structure. Removing toxic additives from polymers would move chemical recycling closer to a circular economic reality.

 Clearly some forms of chemical recycling can complement mechanical recycling to keep essential, non-toxic plastic in the circular economy. But in its current forms, it has too many elements of linear economy associated with it to lay claim to ‘circularity’.