Claims such as “compostable” and “biodegradable” are not necessarily best for the environment
Recently, a number of businesses have been introducing bioplastic products.
Bioplastic products are presented as an alternative to what can be called “conventional” or “traditional” plastic made from non-renewable fossil resources in the form of oil and natural gas, and which further contribute to environmental damage when the product is incinerated after use. Moreover, a number of cardboard products and cardboard-bioplastic blends have also been introduced alongside claims such as “compostable” and “biodegradable.” As a business or as a consumer, it is important to take care not to be misled by prefixes such as “bio” and words such as “compostable” and “biodegradable”, believing that this means the material or product is therefore sustainable and has no environmental impact. In the following, we provide an introduction to some of the concepts and evaluation methods for bio-based materials.
By Michael Søgaard Jørgensen, Associate Professor in environmental innovation and sustainable transition at Aalborg University, Copenhagen
Bioplastic – from plants or plant waste?
Bioplastic – from plants or plant waste?
Bioplastic can be produced using material from
- Plants containing sugar, such as sugar cane, sugar beet, bamboo, corn and other cereal grains.
- Raw materials containing lignocellulose, such as wood
There are a number of different ways of processing bio-based raw materials into chemical substances that can form the basis for the production of bioplastic, such as fermentation, catalysis, gasification, pyrolysis, and decomposition of sugar compounds.
There are different types of bioplastic.
There are a number of different ways of processing bio-based raw materials into chemical substances that can form the basis for the production of bioplastic, such as fermentation, catalysis, gasification, pyrolysis, and decomposition of sugar compounds. Different bioplastics can also be used in the manufacture of packaging, bags, bottles and foils, amongst others. If bioplastic products are incinerated, only the CO2 absorbed by the plant during its growth is released, therefore bioplastics are sometimes referred to as being carbon neutral.
It is important to remember, however, that it also requires energy to produce and transport the bioplastic products, meaning therefore that bioplastic products are not CO2 neutral unless the energy used to produce and transport the plastic is renewable energy, which is rarely the case.
Moreover, a substantial reduction of our environmental impact requires a substantial reduction in greenhouse gas emissions.
Therefore, it is necessary that products are manufactured with a long lifetime, so that the store of CO2 is “bound” within the bio-based product rather than being released when the product is incinerated after a short period of time.
A critical difference is whether the bioplastic has been manufactured using the whole plant or using plant waste.
A disadvantage of bioplastics made with the whole plant such as sugar cane, sugar beet and corn is that space is required to grow these crops in order to produce the biomass. The same area could have been used to grow food products, and there has therefore been some discussion about this type of bioplastic competing with food production. As a result, bioplastics made from plant waste – for example bagasse from crushed sugar cane – are considered more sustainable than bioplastics made from whole plants.
There are currently very few bioplastic products manufactured using plant waste on the market. It is important that businesses using or selling bio-based materials in their packaging or products ask their (potential) supplier for documentation detailing the origin of the biomaterials used, including whether plants or plant waste has been used and whether the plants or plant waste used originates from conventional or organic farming. Not all products that are claimed to be made from bioplastic contain bioplastic alone. In some products, only a small amount of bioplastic is added to a product, while the remaining material is conventional plastic from oil and natural gas. The bioplastic content level is therefore also important information to obtain from suppliers.
Waste management of biodegradable material
Suppliers often emphasise the biodegradability or compostability of bioplastic products. From an environmental point of view, however, it is a bad idea to convert biodegradable materials such as bioplastic, cardboard and paper into compost and energy, as one loses some of the energy used to produce the original material and give it its properties.
Instead, the material should be recycled as material – plastic, cardboard or paper. This way, you avoid losing the energy used to make the product, which can be said to be “embedded” in the product.
Biodegradable plastics are chemically distinct from non-biodegradable plastic types by way of being produced in such a way that microorganisms can break down the chemical bonds in the long carbon chains into smaller molecules such as CO2, water and methane. However, this doesn’t mean that biodegradable plastic can be put in a compost heap or thrown out into nature.
Composting of biodegradable plastics requires special industrial composting plants with high temperatures, oxygen, humidity, light and a large concentration of microorganisms. Biodegradable plastic is therefore not usually degradable in nature.
Bioplastics can break more easily that other kinds of plastic, however, and have a very short lifespan, which makes recycling more complicated.
However, there are bioplastics available that can be recycled, so it is possible to request these from suppliers.
Products made from recycled materials: quality, traceability and recyclability
Products made from recycled material have less environmental impact than products made from new (“virgin”) material – e.g. plastic, aluminium or cardboard. Every time a material can be recycled, resources are spared, and with them the extraction or production of new raw materials.
For some materials, it is necessary to add a certain amount of virgin material if recycled raw materials are used, as essential elements of the material quality – e.g. fibre length in cardboard – are reduced each time the material goes through the recycling process. Just as traceability of bioplastics is important, so is the traceability of recycled materials, e.g. how the reprocessing from discarded products to recyclable material has been carried out.
In Denmark, for example, the revelation of Danish plastic waste’s long journey around the globe and its reprocessing under conditions that are harmful to both human health and the environment helped to demonstrate the importance of traceability of recycled materials.
The demand for traceability from a supplier is, in principle, no different to a company being used to demanding traceability and information about the manufacture of a product or virgin raw material from suppliers or their sub-suppliers. If possible, a product made from recycled materials should subsequently also have the ability to be recycled, i.e. a recycled material product should be recyclable itself. Even though recycling might not be possible – for hygiene reasons, for example – the use of recycled material as a raw material is still beneficial for the environment.
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