Supposedly sustainable plastics fare no better in eco-audits than those produced from crude oil. Therefore, we do not currently use them as packaging material.
What are bioplastics?
Bioplastics, or biopolymers, are divided into two categories depending on whether they are produced from
- Renewable raw materials (starch, oils, sugar, cellulose, etc.) or
- Biodegradable fossil resources.
The first category, plastics produced from renewable raw materials, is further subdivided into
- Biodegradable materials and
- Plastics which are chemically identical to fossil-based plastics (e.g. sugarcane-based PET), and are therefore not biodegradable.
Are bioplastics organic?
The term «bioplastic» does not indicate that either the raw materials or the products are produced by organic agricultural methods. In principle, however, it seems sensible to use renewable raw materials instead of crude oil to produce plastics. Yet the vast majority of bioplastics cannot be produced without the use of petrochemical plastics. In fact, depending on the required attributes of the material, they can comprise up to 40 percent conventional plastics. Although the end product may still be biodegradable, their overall eco audit is not good.
An analysis of the eco-audits of an array of different products shows that, so far, the majority of bioplastic packaging fares no better in environmental terms than products made from petrochemically produced plastics. However, it is difficult to compare the findings: bioplastics are better in terms of the consumption of fossil resources and their impact on climate change but they are let down by the intensive agricultural methods used to cultivate them. The agricultural methods involved in producing the raw materials for bioplastics are frequently not sustainable. They may even be in direct or indirect land-use competition with the production of foodstuffs and, especially where maize is concerned, are based on genetically modified seeds.
Measures to improve the sustainability of bioplastics
Efforts are being made to rectify the downsides of their production. Only when significant environmental progress is made in the production and processing of raw materials will we consider bioplastics as a packaging material. The first measures aimed at improving the situation are already being implemented. Waste from agricultural production and food processing, for instance (secondary raw materials) and alternative raw materials are being used as the basis for bioplastics.
Recycling is another critical aspect
As well as production, the correct recycling of packaging made from bioplastics is another important issue. If the packaging is biodegradable, it is certified and labelled according to the appropriate standard. In practice, however, it takes significantly longer for it to degrade at organic waste processing plants than under laboratory conditions. Moreover, the degradation products which occur during the composting or fermentation of BM provide scarcely any beneficial nutrients for the soil. Furthermore, to the layperson, bioplastics are barely distinguishable from conventional plastic products. It is therefore vital to ensure that consumers and recycling companies are able to clearly distinguish the products and can recycle them correctly. The consensus document of the BM round table on the labelling of biodegradability must be observed at all times. Otherwise, biodegradable packaging must also be disposed of as household refuse, undoing all its benefits.
Polymers produced from sugarcane for the manufacture of substances such as PET are, by contrast, chemically identical to plastics produced from crude oil and can be recycled in the same way (e.g. sugarcane-based PET drinks bottles).