Waste bags made from corn starch or castor oil-based bio-wall plugs: bio-plastics are in vogue. But what does the environment actually gain from them?
‘Bioplastics’ is still a confusing term. No wonder, because it can mean many things. For example, it might be used to refer to plastics that are made from renewable raw materials but are still not biodegradable. Conversely, there are also biodegradable plastics that are produced from fossil raw materials such as oil.
However, one thing is clear: demand is on the rise. According to market data from European Bioplastics the production capacity for all bioplastics in 2020 was around 2.1 million tonnes.
Renewable raw materials come into their own where they drive business and technology. The crucial factor here is durability. Sugar cane, wheat or hemp score particularly well here. But animal products such as milk as a base are also welcome. The most common place to find bio-based plastics is in your car or home, for example as building components or food packaging.
Bio-based plastics can sometimes even do a better job than fossil plastics. For example, Brazilian researchers have succeeded in developing a bioplastic derived from the fibres of bananas, pineapples and other plants. It is a lean 30 per cent lighter and up to four times stronger than conventional plastic.
Other people have also been tinkering with such unusual raw materials, too. For example, algae are now moving into less wet realms and, as bioplastics, are supporting the construction of 3-D printers. Or fungal cells. They are finding a new future as polymer materials far from the forest floor.
But when is a plastic biodegradable? It is precisely when microorganisms can break it down into water, carbon dioxide and biomass – and it doesn’t matter what the plastic was made of. However, ‘compostable’ does not mean that you can simply dump plastic on your compost heap. This is where industrial composting plants come in.
But hold on! You can actually throw flower pots made from biodegradable plastics onto your compost heap at home. They turn into biomass and benefit the soil in the process. It works a bit like that in agriculture. Organic mulch films on fields can simply be ploughed under after use. This means that there is no need to clean up after working on the land – and plants are not damaged either.
Don’t worry. Even if grain or dairy products are used for bio-based plastics, neither food nor feed production will suffer. European Bioplastics estimates that only 0.015 per cent of the world’s agricultural land was used for the cultivation of renewable raw materials that went into the production of bioplastics in 2020. Of course, that would change with increased demand. Bioplastics based on plant residues or derived from biogas plants are often the preferred solution in order to avoid polluting land or using foodstuffs.
Nevertheless, biodegradable and biobased plastics are not climate-neutral. After all, every production step consumes energy – for example, sowing, harvesting and transport. For this reason, the decision for or against bio-based plastics should always be linked to the question of the life cycle of a product.
Photo credit: iStock.com/Arsenil Palivoda