Plastic production has accelerated in recent years and is forecast to reach 600million tonnes by 2030. Most of this is not biodegradable, and 30-50% is produced for single-use applications. Plastic waste has become an increasingly pressing issue in recent years.
Biodegradable plastics and better recycling strategies are two promising approaches to address this. Both techniques are discussed in the recent IDTechEx reports “Bioplastics 2020-2025” and “Green Technology and Polymer Recycling: Market Analysis 2020-2030”.
Bioplastics – polymers produced from biological feedstocks – dominate the landscape of biodegradable plastics and there has been a lot of excitement over the past decade around the potential of biodegradable bioplastics, such as polylactic acid (PLA) and polyhydroxyalkanoates (PHAs), which theoretically break down naturally. However, just because a material is sourced biologically does not necessarily mean it will break down in the natural environment in a timely fashion.
The second issue is around what is meant by a “biodegradable” plastic. You might interpret this as plastic which breaks down in the natural environment in weeks to months. However, not many fit this definition. PLA, for example, is commonly labelled as biodegradable, but will only break down in an industrial composting facility where it can be heated to a high enough temperature. A PLA bottle dumped into the ocean will take hundreds of years to break down. Unfortunately, many regions around the world do not have access to these industrial composting facilities, meaning widespread uptake of PLA plastics would not in practice lead to any environmental benefits.
This is not the case for all bioplastics – PHAs break down in the natural environment over months, as do starch blends and nanocelluloses. An overview of the biodegradability of all common bioplastics is given in the IDTechEx report “Bioplastics 2020-2025”, as well as a discussion around the nuances of the term “biodegradability” and end-of-life options for bioplastics.
Recycling is another potential avenue for overcoming the plastic waste problem. Although efforts have increased in recent years, only a small amount of plastic waste is actually recycled – National Geographic has reported only 9% of the world’s plastic waste is recycled.
Existing recycling technologies rely on mechanically sorting and melting plastic waste, which frequently leads to “down-cycling” of materials due to high levels of contamination. However, a range of emerging alternative recycling technologies could lead to opportunities in the polymer value chain. For example, solvent extraction can yield a pure polymer with mechanical properties similar to virgin material. Techniques such as pyrolysis and other forms of depolymerisation can create fuels and chemical feedstocks from waste plastics that go back into the wider value chain. Each of these techniques, alongside the wider market for polymer recycling, are discussed in the IDTechEx report “Green Technology and Polymer Recycling: Market Analysis 2020-2030”.
Historically low oil prices that make conventional production and disposal of single-use plastics by far the cheapest option, although emerging technologies are helping to change this. Aspects of the systems are in competition– for example, an increased focus on recycling will lead to a smaller potential market for bioplastics, compounding the economic issues that the field faces. However, despite this, both technologies must grow if the world is to take meaningful action against plastic waste.