The Basics of Advanced Recycling

There is a strong push from consumers, investors, NGOs and other stakeholders to solve the issues related to the growing problem of plastic (packaging) waste pollution of our oceans and the environment. And as this call for a circular economy grows around the world, brand owners and governments have responded with various sustainable packaging strategies and circular economy policies drafted in recent years. These strategies primarily target the recyclability and recycled content of plastic packaging. Solving the plastic waste problem has become a priority for the entire plastic packaging value chain. Advanced recycling, or chemical recycling, is a promising group of technologies that could contribute to the circular economy targets by providing solutions to plastic waste. Where recycled plastic from mechanical recycling has limited applications, for example because of regulatory obstacles (e.g. not approved for food grade purposes), advanced recycling can give plastic product producers a true virgin plastic which could overcome some of these hurdles. The EU Plastic Strategy, for example, acknowledges that advanced recycling “can have a powerful effect” in reaching a circular economy (EU Plastic Strategy, 2018). We have therefore witnessed a surge in announcements of investments in advanced recycling initiatives that could provide a solution to this societal demand. But is advanced recycling the silver bullet to this challenge?

Global plastic production growth has, besides a small dip in 2008, been steady and consistent since its large scale introduction in the 1950s. In 2015, total plastic produced reached 381m metric tons (Geyer et.al. 2017). Plastic packaging uses 36% of the plastics produced, the lion’s share of which is used to package food and beverages (see Figure 1).

Plastic packaging is popular because of it has many advantages – it is lightweight, versatile, cheap, and creates an effective protective barrier around food products, thus increasing shelf life. But, the growing use of plastic packaging also puts stress on our environment. Most disposed plastic packaging is either burned for energy recovery, emitting greenhouse gases, or dumped on landfills (Geyer et. Al., 2017). Leakage from landfills or waste that is never picked up is causing the pollution from plastic waste that reaches rivers and oceans and affects marine life (Jambeck et. al., 2015). It is also known to degrade into micro- and nanoplastics, finding its way back into our food chain (EFSA, 2016). Governments are implementing circular economy policies to reduce that stress on our environment, and companies across the plastic packaging value chain are undertaking initiatives to help curb this trend. Plastic recycling is one part of the solution. It helps reduce greenhouse gas emissions and prevents plastic from becoming a pollutant, while simultaneously providing a resource for new plastic products.

Conventional plastic production starts with fossil fuels such as oil or gas. Through refining, plastic production (polymerization), and compounding, a plastic pellet is produced, which can then be converted into products such as film or bottles (see Figure 2).

After disposal and collection, plastic ideally is recycled. Plastic recycling can be divided into four categories (Merrington, 2017):

Primary recycling – Mechanical recycling

Also known as closed-loop recycling, is where the recovered plastic is used in products that are the same or similar (in performance characteristics) to the original product it came from. This can be done both in-house, for example leftover material from a production process that is reused as feedstock, or externally, for example recycling of PET bottles collected through bottle deposit return schemes, that are used to produce new bottles. Another example is Tesco’s milkman return scheme for closed-loop recycling.

Secondary recycling – Mechanical recycling

Collected, sorted and reprocessed plastic is mechanically recycled in applications that have less demanding attributes compared to the virgin resins. The Mars Petcare recycling programme with Terracycle (where flexible packaging is converted to park benches) is an example of secondary recycling.

Tertiary recycling – Advanced recycling

Collected plastic is used as feedstock in a process that regenerates chemicals or creates fuels. An example is glycolysis of PET drinking bottles into feedstock for virgin PET. Mondelez International’s Philadelphia cream cheese packages also contain plastic made through advanced recycling.

Quaternary recycling – Waste-to-Energy recycling

Plastic waste (together with other forms of waste – organic etc.) are burned to produce heat and steam, which in turn is used to generate energy. Globally, until 2015, 9% of all plastic waste was incinerated. (Geyer et. Al., 2017)

All plastics can in principle be recycled using primary, secondary or quaternary recycling – but the challenge remains the economic and environmental viability. Quaternary recycling is the dominant method for plastic recycling today. However, despite being energy dense, the burning of plastic waste does not come without its problems. Waste-to-energy plants are often faced with land restrictions, economies-of-scale issues, and greenhouse gas emissions challenges. Mechanical recycling, which is also a widely used form of recycling, has some challenges too, especially when it comes to food contact packaging, for example:

These challenges can be partly controlled by rigorous checks on incoming materials, impurity removal (melt filtration) and assurance of purity. There is also a growing trend in the use of compatibalizers[1] that can improve the properties and functionality of mechanically recycled plastic.

Food packaging is demanding, with high-quality feedstock requirements. For example there should be no transfer of odour or flavour from the food packaging to the packaged products. Recycled plastic pellets can be reused in food or beverage packaging if approved for direct food contact, the regulations for which differ from country to country. This is one of the factors that inhibits uptake of higher volumes of mechanically recycled resin in food and beverage plastic packaging – there are only few countries that allow for this.

[1] Compatibilizers help blend different types of plastic that are immiscible during secondary recycling. This increases the mechanical properties of the recycled plastic, increasing usability.

Advanced recycling, chemical recycling or tertiary recycling, uses thermochemical reactions to break plastics down into completely new products such as virgin plastic, monomers, fuel, energy and other commodities. Advanced recycling technologies are still in early stage development and there are numerous stakeholders refining the technologies and developing these for commercial purposes. Advanced recycling is expected to supplement mechanical recycling infrastructure in countries that already have such infrastructure in place. There’s a wide array of processes being developed with which this can be done. For simplification purposes we have sub-divided them based on the type of input (see Figure 3).

Cracking

Cracking processes break down plastic in a closed environment under high temperatures and little or no oxygen. Another word for this is pyrolysis. Cracking is suitable for an input of mixed plastics. The output is a raw material or fuel that can be fed back into the plastic production process (see figure 2). An example of cracking is the pyrolysis process performed by Nexus Energy in the US. Tesco’s new cheese packaging is also made using pyrolytic cracking technology.

Gasification

Gasification resembles cracking and also focuses on an input of mixed plastics. In contrast to cracking, oxygen and/or steam are added in a closed environment at high temperatures. The output is a 'syngas' (synthetic gas) that can be used as raw material and fuel. Shell, the Port of Rotterdam and other stakeholders have collaborated to build an advanced recycling plant that will use gasification technologies.

Chemolysis

Chemolysis is a collective term for advanced recycling in which selected plastics, such as PET from drinking bottles, are processed. The individual plastics are chemically treated and converted into monomers. Monomers are the building blocks for polymers and are used in the plastic production process to produce new virgin plastic. An example of this is glycolysis, a type of chemolysis, by Ioniqa. This enables them to convert (colored) PET into monomers, which can be used in the production of virgin PET granules.

Other

Other advanced recycling technologies are also under development. One example is enzymatic recycling, where a single polymer (e.g. PET) is extracted from a combination of different plastics. This helps the recycling of multilayer food packaging. Carbios is a frontrunner when it comes to enzymatic recycling technologies.

The big difference between advanced and secondary recycling is that the output of advanced recycling can replace new raw materials, which can be approved for use in the production of new plastic food and beverage packaging. Another difference is that advanced recycling technologies are still emerging and there is no clearly winning concept or technology yet. There is also no evidence yet that these technologies will become economically viable on a large scale.

The investments into advanced recycling are ramping up. A huge number of coalitions are being made with companies from the petrochemical and food packaging industry to invest in advanced recycling. This, coupled with the ambitious sustainability commitments announced by food & beverage companies, seems to help accelerate the interest in advanced recycling. Table 1 shows examples of recent announcements of advanced recycling partnerships.

The financial and economic viability of advanced recycling must be safeguarded – there are concerns about the real environmental impact of these technologies, especially from NGOs. For example, advanced recycling can be energy intensive compared to secondary recycling (GAIA, 2020). The by-products from specific advanced recycling processes such as chemolysis can be harmful to the environment. These downsides need to be taken into consideration for advanced recycling to thrive.

Supportive legislation with clear definitions of advanced recycling would provide an impetus to projects to avoid regulatory market uncertainty. An example is the EU Plastics Strategy, which states: “Innovative solutions for advanced sorting, chemical recycling and improved polymer design can have a powerful effect”. With the Taxonomy Regulation, a new European law to steer public and private investments to green economic activities, primary plastics made through advanced recycling are considered potentially green. In the US, for example, there is no uniform classification of ‘advanced/chemical recycling’, which can be a considerable barrier for investments.

The Dutch government, on the other hand, takes it a step further, having initiated a plan to optimize the investment climate for advanced recycling. The plan aims to reach at least a 10% share of feedstock for plastic production that comes from chemical recycling of plastics by 2030, equivalent to a minimum of 250 kiloton installed capacity.

Is advanced recycling the silver bullet to the plastic packaging waste problem? We think advanced recycling can complement existing recycling methods – so in one way or another it can help increase global recycling rates and accelerate the transition towards a circular economy. The plastics created as an outcome meet the high quality requirements for food contact packaging, something other recycling methods find challenging. This, coupled with its ability to handle mixed plastic waste streams, makes it a promising recycling method.

However, advanced recycling is at too early stage of development to conclude whether it is the ultimate solution for the plastic packaging waste problem. There are concerns about its energy efficiency and the toxicity of its by-products, both of which could have huge implications on the environment. The wide range of advanced recycling processes, from pyrolysis to enzymatic recycling, makes it a more complex form of recycling compared to others. Thus it is important that more research is conducted to evaluate the pros and cons of the different processes involved. Therefore it will take time, perhaps several years, before advanced recycling could have significant impact, and reach the acceptance level of other forms of recycling.

This is the first introductory publication on what is happening within advanced recycling. In the next publication we will provide insight into the investments, stakeholders and drivers in advanced recycling.

Roland Geyer et. al., (2017): Production, use, and fate of all plastics ever made

European Union, (2018): EU Plastics Strategy

Jambeck et. al., (2015): Plastic waste inputs from land into the ocean

European Food Safety Authority, (2016): Presence of microplastics and nanoplastics in food, with particular focus on seafood

Adrian Merrington, (2017): Applied Plastics Engineering Handbook – Recycling of Plastics

Ina Vollmer et. al. (2020): Beyond Mechanical Recycling: Giving New Life to Plastic Waste

Global Alliance for Incinerator Alternatives, (2020): All Talk and No Recycling: An Investigation of the U.S. “Chemical Recycling”Industry

Co-author: Richard Freundlich