Biodegradable plastic is possible

How sustainable is bio-plastic?

After plastics have come under fire and are often considered unsustainable, especially in the packaging sector, the industry reacted more intensely and is looking for alternatives. More and more products are coming onto the market which, with the term "bio-plastic" and an environmentally friendly design, promise the consumer general environmental compatibility. So far, the global market share of these products is less than 1% and, according to the forecast of the Institute for Bioplastics and Biocomposites (IfBB), will not rise above 2 to 3%. These numbers are related to discussions about the usefulness of bioplastics. The current market situation confuses the consumer more than a sustainable solution to the problem with plastic waste is emerging.

Photo: © allasimacheva -

How ecological are these materials actually compared to conventional plastics? Which criteria help to assess the sustainability of the respective bioplastics? What should you watch out for when purchasing and disposing of "bio-plastic"?

Bamboo cups are also advertised as "natural cups" that are biodegradable and recyclable. Manufacturers do not offer these as "bio-plastic" but as an ecological alternative, and they usually only contain around 30% bamboo fibers. Melamine resin, a plastic made up of formaldehyde and melamine, creates shape and cohesion.

The material bio-plastic

There are two groups of bio-plastics: biodegradable plastics and bio-based plastics. For plastics, the prefix “bio” does not necessarily mean that the material in question was made from renewable raw materials and that it is also rapidly biodegradable. There is still no fixed labeling for bio-plastics. The Plant Bottle seal was introduced by the manufacturer for bottles made partly from vegetable raw materials. However, the consumer does not recognize either the type of plastic present or the ecological benefit of the material. The award of the logo with the seedling by the association "climate-neutral packaging" for compostability follows the criteria of the European standard EN 13432. After that, within 12 weeks 90% of the material must be broken down into plastic particles smaller than 2 mm and after 6 months into carbon dioxide (CO2) be transformed. According to BUND, however, this logo does not automatically mean that it is environmentally safe.

How ecological are biodegradable plastics?

Biodegradable plastics do not necessarily consist of renewable raw materials. They decompose through the biological activity of microorganisms and fungi (e.g. through enzymatic action) under certain conditions (temperature, humidity, residence time) to carbon dioxide (CO2) and water. Composting these plastics has so far offered no advantage. A high consumption of energy and resources for the production contrasts with decomposition conditions, which no garden compost but only (industrial) composting plants offer. Even there, according to the current state of the art, disintegration takes place more slowly (at least 8 to 12 weeks) than the usual composting process (on average 5 to 8 weeks). So plastic particles remain in the finished compost and would be spread on fields and gardens. For this reason, biodegradable plastics are not yet suitable for the organic waste bin and are usually sorted out before composting. The faster disintegration into small particles makes sorting even more difficult compared to conventional plastics. Apart from that, according to the current state of the art, the machines do not recognize whether the respective plastic is compostable and therefore basically sort out all plastics. No ecological benefit can be derived from the biological degradation of these plastics, since the decomposition products water and carbon dioxide (CO2) do not provide any nutrients for the compost. In many places, consumers are encouraged to dispose of biodegradable plastics in the residual waste bin, as at least thermal energy is obtained through waste incineration.

How ecological are bio-based plastics?

Bio-based plastics consist of biomass. Both starch and cellulose-based raw materials, such as maize, sugar beet, miscanthus and sugar cane, as well as raw materials based on oilseeds such as rapeseed, sunflower oil and palm oil are used in the production. Wood is also used as a renewable raw material - in contrast to animal raw materials. The term “agro-plastics” is more suitable, since bio-based plastics are not necessarily organic products from organic farming. The materials produced in this way can be identical to plastics made from fossil raw materials (“drop-in”) and are then not necessarily biodegradable. Recycling is possible, as is the case with polyethylene terephthalate (PET) bottles.

Not all bio-based plastics are made from 100% renewable raw materials. They can contain proportions of petroleum-based plastics. Chemical additives, often obtained from petroleum, are used to influence the properties of bio-based plastics. These additives may find their way into the food from the packaging and uncontrolled into the environment via composting. Even if, according to the Federal Environment Agency (UBA), the life cycle assessment of bio-based plastics is no better than that of petroleum-based plastics, these materials are relevant for industry in view of the declining petroleum reserves.

The impression that unlimited resources are available with renewable raw materials is deceptive, because soils are also a limited good. Cultivation (often in monocultures), the use of fertilizers and pesticides as well as irrigation use up resources and set limits. The extraction of renewable raw materials quickly competes with the production of food and animal feed. Bio-based plastic bags may not be disposed of in the organic waste bin unless they are biodegradable and certified according to EN 13432 and EN 14995. Disposal takes place in the yellow sack or the yellow bin.

Assessment of the current status from an environmental point of view

According to forecasts by the Institute for Bioplastics and Biocomposites (IfBB) in Hanover, biodegradable plastic is not the solution of the future. The proportion of compostable plastic will hardly increase in the coming years.

Overall, bioplastics still do not offer any ecological advantages over conventional plastics. Composting remains problematic.

Tips for consumers:

  • Less is more: plastic that is not used is better than any plastic.
  • Save plastic packaging wherever possible.
  • Also be careful with ecological alternatives.
  • Use reusable packaging as often as possible.
  • Find out more about the disposal requirements for bioplastics from your local waste disposal company (often residual waste bin or yellow sack or yellow bin).
  • Bioplastics do not belong in the garden compost because the temperature is too low to break down.


Sources and further information:

Federal Environment Agency: short position bioplastics

Planet knowledge: bioplastics

Fairlis: Bioplastics - how sustainable is the plastic alternative really?

Stiftung Warentest: bamboo cups put to the test