Most plastics start the beginning of their life as raw materials which are primarily crude oil, but sometimes natural gas and coal. These raw materials go through a chemical process where they become chains of polymers that are linked together repeatedly and then moulded and coloured to become the plastics that we see every day.

The issue then arises with what happens to these plastics at the end of their lives. We know that much of the plastic we use has a very short lifespan, and we know that not all these plastics are recyclable. The ones that can be are often, ‘mechanically recycled.’ The plastics are sorted by type, ground into powders, and then reused to make new plastic products. Unfortunately, even the plastics that can be recycled this way are only able to be done so a finite number of times before the polymers become weakened and degrade.

In the past decade, ‘chemical recycling’ has become increasingly popular as a potential solution to this problem. Chemical recycling is a broad term that describes a range of emerging technologies which allow mixed polymers and multi-layered plastics to be turned into raw material that can then be converted into fuel. Because chemical recycling can be used on contaminated, layered or hard to recycle plastics, the process allow items that would otherwise end in a landfill to be used again.

Of the different technologies within chemical recycling, feedstock recycling is the most versatile. This refers to one of three processes (Pyrolysis, Gasification, or Hydrogenation), where heat is applied to the plastic, allowing the original chemical building blocks to be reverse engineered.

Fuel such as diesel, petrol or a type of oil similar to the crude that was used to create the plastics in the first place, can be recovered.

If all this technology is out there, what’s the problem?

Mechanical recycling has very real limitations in that it is only possible to do this a small number of times.

Chemical recycling though touted as a viable solution, has sceptics pointing out that while a good solution on paper, it actually takes more energy to turn the plastic back into fuel than the amount of fuel being ‘created.’ This generates a lot of CO₂.

This CO₂ when released into the atmosphere, makes it more of a climate polluter than a climate protector. The process costs a lot more too, and more importantly, some claim it is distraction from the plastic crisis rather than a solution.

So what’s next?

There is light at the end of the tunnel. Chemists at St Petersburg State University have been developing polymers made from biomass – meaning it comes from a plant or animal instead of a gas or oil. The key components for these polymers are from natural alcohols such as menthol, and borneol (a compound that comes from the oil of the white fir tree). They can be recycled by primary or secondary recycling, many times without degrading and harming the environment.

While the research into these types of polymers is still in its infancy, it would limit our reliance on using petroleum resources for creating and recycling plastics. And, as a result, reduce carbon emissions.

Studies continue to test the resilience, strength, and elasticity of the biomass polymers, once these have been established, it could be an exciting and sustainable step in plastic production.