Bioplastics are becoming more and more popular, with plenty of items available as alternatives to conventional plastics, from bio-straws to shopping bags and cooldrink bottles. But what makes bioplastic different? Do all the “bio”-terms mean the same thing? And are they necessarily better for the environment?
Research performed by WRAP (one of the world’s leading sustainability NGOs) in 2007 showed that most consumers do not know the difference between the different types of plastics and generally associate the word “bio” as meaning “good”.
Here are a few useful terms to know:
Bioplastics refer to bio-based plastics, which are just like everyday plastics, but they have been produced from renewable sources (like plants) instead of fossil fuels. These plastics are not necessarily biodegradable and can be non-degradable, which means that they don’t break down by themselves (see Figure 1).
Biodegradable plastics are items made from renewable (plant-based) or non-renewable (fossil fuel-based) resources that will break down by themselves over time into organic matter that, if treated correctly, is not harmful to the environment. How much plastic will biodegrade depends strongly on the conditions the plastic is in (temperature, available water, and oxygen).
Compostable plastics break down by themselves into organic biomass, but only in an industrial composting facility or home compost heap when temperatures exceed 60 ᵒC. The term biological plastic is sometimes used, but this can either refer to the origin of the material or what happens to the plastic at the end of its life – so it doesn’t really cut through the confusion.
The bottom line is, biobased does not mean biodegradable. Just because biodegradable and compostable products can break down, doesn’t mean they will, since this can only happen under very specific conditions. Added to this, biodegradable and compostable plastics can lead to increased littering in the environment when people assume that they will break down by themselves, regardless of the conditions.
Figure 1. The diagram highlights the overlap and differences between these terms, based on based on the European Bioplastics version (https://www.europeanbioplastics.org/bioplastics/materials/).
Another unintended consequence of bioplastics is its effect on the recycling industry. Traditional plastics, whether fossil fuel-based or plant-based, are generally recyclable, and some are very successfully recycled. For example, cooldrink bottles made from PET plastic can be recycled into new bottles, insulation, and a host of other products (see PETCO for more info). Biodegradable plastics, however, cannot be recycled in the same way. This can cause confusion if products are not clearly labelled or marked, and well-meaning consumers may contaminate plastic recycling streams with degradable products.
Carbon emissions are another consideration for bioplastics – a timely consideration with COP26 currently taking place. Bio-based plastics are made from renewable resources like starch, corn, and sugar cane. When these renewable sources are grown, the plants naturally absorb carbon dioxide. This is in stark contrast to producing plastic from fossil fuels. The extracting, processing, and transporting of fossil fuels has the highest emissions in the plastic product’s life cycle (see Figure 2). However, plant feedstocks for bio-based plastics are often shipped great distances to manufacturing plants before they eventually become plastic products. This process increases the item’s carbon footprint – a measure of how much carbon is produced over a product’s entire lifecycle. Of all the end-of-life processes for plastics, recycling produces the lowest carbon dioxide emissions.
Figure 2. Normal (fossil fuel-based) plastic’ vs. Bioplastics (plant-based; figure taken from https://wdkadesignforimpact.wordpress.com/2015/01/28/biodegradable-plastics/)
So, what can we do? What products should we be buying?
Compostable and biodegradable plastics have their place but they need to be fit-for-purpose and they need to be responsibly managed, to ensure they perform according to the necessary certifications and that they don’t disrupt mechanical recycling streams (like the very well-established PET recycling sector in South Africa).
Ultimately, whichever product we purchase – whether it is made from glass, paper, bioplastic or traditional plastic – has been extracted from the earth; it therefore has a direct impact on the environment.
If you choose to buy a bioplastic item, ensure that you understand how it must be responsibly disposed of. Stick with the 3 Rs; Reduce, Reuse, and Recycle.
Above all, don’t let your plastic items – whether made from fossil fuels or plants – end up in the environment.