Emerging Plastics Recycling Technologies: Where Are They Headed? Part 1

This two-part series assesses several emerging recycling technologies, including chemical processes and an experimental biological process, as well as a few more established mechanical recycling methods. It goes on to discuss what some industry experts say is needed in the way of policy and funding to advance the emerging technologies.

Plastics have multiple applications, and they are cheap to produce. But the explosion in manufacturing and consumption far outstrips the capacity to manage them at the end of life. The flow of plastic into the ocean is projected to nearly triple by 2040, and the current methods of handling the waste comes with steep expenses that overshadow the low cost of virgin plastics, says The Pew Charitable Trusts.

Policymakers, consumers, and some brands and manufacturers –all aware of this problem –are driving a trend: the rethinking of the world’s approach to plastic, including ways to recycle it. New technologies, and tweaks to old technologies, are evolving aimed at improving recovery and processing of these materials to keep them out of the environment, and in circulation at their highest use.

Economist Impact, the research arm of the Economist Group, which reports on global political and economic affairs, has released a study: Rethinking Plastics in a Circular Economy, funded by Dow Chemical that assesses several recycling technologies under the categories of chemical and biological approaches (often called “advanced recycling) as well as some mechanical techniques.

Economist Impact’s assessment is broken down into five categories:

The chemical processes explored are:

Also examined was a biological process:

Also assessed were these mechanical processes:

Martin Koehring, director of the research for this study says, “There is a huge divergence between these technologies, and they come with tradeoffs, which is why this study is so important. It comprehensively assesses each plastic recycling technology for attributes that will be important considerations to policymakers, investors, the plastics industry, and other stakeholders who will be key to advancing these technologies.”

Some of the main takeaways are that the chemical processes, especially pyrolysis, gasification, and hydrothermal recycling, produce high-quality, high-value outputs. And they can work with multi-material packaging, flexible packaging, and mixed waste streams.

All the chemical technologies scored high for their ability to process food-grade materials (flake-to-preform was the one mechanical process that also performed well in this area). Enzymatic hydrolysis also is effective with food-grade and leads the way in opportunities for upcycling, delivering a product of similar or higher value than in its first life.

A drawback of the advanced processes, notably pyrolysis, gasification, and hydrothermal recycling, is that they are energy-intensive and can generate carbon dioxide emissions unless powered by renewable energy.

Additionally, many of them depend on chemical reactions that present potential safety hazards. So, they require high investments in engineering and construction as well as advanced safety protocols to mitigate associated risks.

And with the chemical processes the recycled output will require a lot of preparation to produce new plastic materials.

Study interviewee Suhas Dixit, founder and chief executive of APChemi, said, “You cannot just take plastic oil [after pyrolysis] and start feeding it into a cracker.” APChemi builds conventional thermal pyrolysis recycling plants globally.

Chemolyis, however, was an exception, found to need little preparation prior to production compared with pyrolysis and gasification.  Though Koehring projects it will be commercially viable only on a large scale.

Of note, he says, “With many chemical technologies, and the biological process we assessed there are questions around technical maturity and operational capacity. Many of these advanced recycling technologies are not proven at large scale, and the path to commercialization is not there, while most of the mechanical technologies we examined are commercially viable, with high operational capacity.”

Of the “advanced” processes, gasification, catalytic and non-catalytic pyrolysis, and hydrothermal technologies are the furthest along; they’re at early commercial installation stages; a few are already operating on a commercial scale. Chemolysis is at the demo stage. And enzymatic hydrolysis and plasma pyrolysis are still at lab stage.

On the “downstream integration” front, the mechanical options were the strongest. They do well to integrate the recycled output into the next step in the value chain.

Flake-to-preform ranked highest in ability to close the loop (use material to make original product). But because it can usually only return materials to their original format this option is limited in terms of applicability to various materials or products.

Overall, the mechanical processes had a lesser quality output than advanced recycling methods, sometimes losing quality during processing, or at least unable to be upcycled into a higher quality product.

Looking ahead, chemical recycling technologies are well placed to complement mechanical recycling, Koehring says.

“Both have limitations and advantages. While advanced chemical technologies have potential to produce higher quality and higher value output, mechanical recycling will continue to be the primary path for some materials because they require fewer steps and are already established and commercially viable.”

Koehring emphasizes policies and industry initiatives are needed in order to implement and scale these innovations and strengthen the overall recycled plastic value chain. Stay tuned for Part 2 of this series for thought leaders’ ideas on what’s needed on the policy front, as well as other considerations, for scaling.