Non-energy demand for oil, particularly chemical feedstock demand, has been one of the fastest-growing portions of oil demand over the past decade. This trend is set to continue over the coming decades as fuel demand languishes on increasing decarbonisation goals. Meanwhile, top line demand for polymers (HDPE, LLDPE, PP, PET) will continue to grow in the coming years with higher use in durable (automotive and construction) and non-durable applications (fibres and packaging).
Leakage of plastics into the environment (especially single-use plastics) has led to significant policy initiatives to reduce consumption and or, increase the amount of recycled content in packaging to create a circular economy and reduce the use of virgin materials and make waste valuable. This emerging value chain has seen some great businesses turning plastic waste into all manner of commodities from railway sleepers to active wear.
To scale up the inclusion of recycled content we need to narrow input materials to make recycling easier. We need to enhance and increase the efficiency of kerbside collection, this starts in the home of course. We need to improve our sorting and processing facilities to maximise returns. As a direct result of increasing efficiencies in collection and sorting the industry can increase volumes of recycled polymers captured from consumer waste. Once a consistent and stable supply is secured, processors can develop consistent and alternative polymer grades which broadens the potential market uses and as a result increases inclusion of recycled plastics in further products and applications.
The EU has mandated to increase collection of post-consumer plastic to 50% or above by 2030. What’s more all plastics are to be recyclable or reusable in the EU by 2025.
Four clear targets form part of the Plastics Pact European Road Map 2025:
1. Design for reusability and recyclability Design all plastic packaging and single-use plastic products placed on the market to be reusable where possible and in any case recyclable by 2025
2. Responsible use of plastics Use 20% less virgin plastics with 10% absolute reduction
3. Collection, sorting and recycling Increase the collection, sorting and recycling capacity by at least 25 percentage points by 2025 and reach a level that corresponds to market demand for recycled plastics
4. Use of recycled plastics Increase the use of recycled plastics in new products and packaging by 2025, with plastics user companies achieving an average of at least 30% recycled plastics (by weight) in their product and packaging range.
Key plastics initiatives that impact the European and global landscape include:
All these acts, policies and initiatives looking to reduce, reuse, recycle, focus on simplifying polymer groups in everyday products and packaging to support the ease of recycling.
Currently mechanical recycling dominates, perhaps due to its simplicity. In mechanical recycling, post-consumer waste is collected at the kerbside, transported to a sorting facility, cleaned, and then ground into flakes. Flake quality, consistency and polymer type determines the ongoing application and inclusion percentage of the recycled polymer.
The following technologies are used as standard for sorting plastic types:
To make mechanical recycling efficient there must be a high level of collection (feed stock) to ensure consistency and volume of supply to secondary markets. In 2018, 32.5% of post-consumer plastic waste in Europe was collected to be recycled, in the United States 15% was and in Australia less than 12% of plastic waste was recycled. In Australia about 85% of plastic waste ended up in landfill. To secure the required value chain for the circular economy it is critical we capture more waste more efficiently – and quickly!
2. Chemical – depolymerisation
Chemical recycling is a broad-based term but in general, it is the process of thermally breaking down plastics into chemical feedstocks which can then re-enter the chemical production process.
Depolymerization technology allows for waste feed streams to be converted into their pure monomers. The most common application of this technology has been to PET. Unlike pyrolysis, depolymerisation of PET needs a feedstock that has a specific chemical composition (bottles). Depolymerisation usually occurs using a solvent, but companies are exploring other options. Depolymerisation is working to good effect and has seen significant investment as large companies such as Coca-Cola who are ‘closing the loop’ to create circular value chains for the products they sell. R-PET (recycled PET) is more expensive than virgin PET, so it’s working.
3) Chemical – pyrolysis
The most common method of chemical recycling is pyrolysis, a proven technology that has been around for decades. In pyrolysis, mixed feed waste plastics are heated in the absence of oxygen (with or without catalysts) to break down long-chained molecules into shorter chained molecules. Temperatures in this cracking process range from 300–900°C and depend on the feedstock used (HDPE, LDPE, PP, etc). The shorter chained “cracked” molecules are distilled into different purity streams that include products such as diesel, jet fuel and naphtha. These purity product streams can then enter back into refinery or chemical operations and be treated the same as ‘virgin’ products derived from crude oil.
As mentioned earlier, a challenge with mechanical recycling is sorting and cleaning. Recycled content from homes is usually mixed which means the recycling centre must clean and sort the waste into individual streams such as HDPE, PP, PET. When we are talking about ‘designing for the circular economy’ and the narrowing input materials and mono-material structures, it’s all to support the recycling process. We need to make it as efficient as possible and create a value chain that is self-sustaining.
Managing contamination limits in mechanical recycling increases the value and usefulness of the recycled polymers. If contamination levels are high, recycled content is often getting down-cycled into alternative end uses such as non-food grade plastic bottles, tarmac filler, or decking.
In the case of chemical recycling, the feed product has lower restrictions on what can be fed into the pyrolysis unit. Some plastics, such as PVC, present challenges in pyrolysis due to the presence of HCL but common plastics such as HDPE, LLDPE, and PP can be fed as a mixed stream. Several countries have banned the use of PVC, which is an effective way to manage input materials.
Chemical recycling is generating a lot of headlines as it allows mixed feeds (mixed polymers) to come into the recycling system at the end of life. In addition, as already stated, chemical recycling produces products that are fungible with traditional hydrocarbons such as naphtha, propane, jet fuel and diesel. While significant investment has been made to scale this technology the reality is by 2030 if all currently planned facilities come online globally and run at capacity, they will only be able to process 375,000 metric tons of feed stocks each year. There is no doubt this will scale and accelerate over the next decade but it does not provide the immediate solution to the recycling challenges that some companies might have us believe.
While chemical recycling evolves we have seen significant commitments from all the major polymer processors to increase the volumes of available recycled polymers to the market. We have also seen high level collaborations, mergers and acquisitions with global recyclers to secure feed stocks to support this injection of recycled polymer. This ‘liquidity’ will provide a solid foundation on which to develop the circular objectives and the required value chain for business. Increasing the specified inclusion of post-consumer polymers can only be achieved if they are readily available.
I see chemical recycling providing a short to medium term solution for the 20% of materials that cannot be effectively changed or improved to support ease of recycling through the mechanical process. Ultimately it will form a key role in the overall strategy, especially as the technology improves but in my view is likely to be superseded by alternative, less energy -intensive processes.
Advancement and continued investment in mechanical recycling will positively impact the short to medium term efficiencies. Historical under investment in mechanical recycling in most developed economies is a direct result of outsourcing or off-shoring sorting and recycling. Domestic market providers were only required to undertake basic sorting of materials prior to export. One of main challenges faced by all developed economies, the need to deal with its own waste and quickly!
Technologies, such as NIR (near infrared) material identification systems ‘tell’ the MRF’s (materials recycling facility) what material group a product is, this commonly used technology, among others, will play an increasingly significant part in improving the efficiency of mechanical recycling when aligned with products that have been designed for the circular economy to further support identification of materials. These types of technologies will have a greater shorter-term impact on waste collection and processing.
So, what next?
We can’t wait for chemical recycling, at best this will provide a short to medium term solution for difficult to recycle materials, but available capacity and scaling will limit its impact.
Chemical- depolymerisation (PET) recycling continues to see significant investment as demand increases for this circular polymer, stakeholder support and close the loop initiatives aligned with regulation and recycling ‘clarity’ support this process.
Mechanical recycling will continue to do the ‘heavy lifting’, improvement in existing technologies in conjunction with mono-material waste streams and intelligent design will see developed economies deliver the mandated recycling efficiencies, reduce or eliminate off-shoring of recycling and increase domestic accountability for waste. These are good 1st steps for many developed economies, accountability will accelerate innovation and further much needed change in our thinking about the waste we generate.