What is bio-based plastic?
Bio-based plastic is made entirely or partly from renewable raw materials, such as wood, corn, or sugar beet. These feedstocks, contain of biomass such as cellulose, starch, or sugars. Bio based plastics can also be produced from waste streams and by products.
In contrast, conventional fossil-based plastic is produced from crude oil and natural gas.
There are bio‑based plastics that consist of the same polymers as the fossil‑based counterparts, such as polypropylene. These are referred to as drop‑in plastics.
There is currently no mandatory minimum level that a plastic must meet to be labelled as bio‑based. However, a bio-based carbon content of at least 20 percent is often required to obtain various labels and certifications for bio-based products. Even though no formal minimum exists, the proportion of bio‑based content must be clearly stated.
Bio‑based plastics are still plastics. Some products containing bio‑based plastics are incorrectly marketed as “plastic-free”. Bio‑based plastics are not necessarily biodegradable, they may be designed to be just as durable as other types of plastics.
Does biodegradable plastic degrade in natural environments?
The term biodegradable plastic refers to plastics that can be broken down biologically under specific conditions, for example in an industrial composting facility. After degradation, the material is converted into natural components such as water and carbon dioxide. The biodegradability of a plastic therefore depends on both:
- If designed for biodegradability or composting
- The conditions it is exposed to after it has been used. Often high temperature and other specific conditions are required for complete degradation.
Many mistakenly believe that plastics marketed as “biodegradable” or “compostable” can be thrown away in nature or in the food waste, however that’s not the case.
- Degradable plastic can cause equally as much damage in nature as non-degradable plastic because the degradation of the plastic partly takes time and partly demands other conditions to break down than those found in nature, which is often the case. It is therefore important that degradable plastic does not end up in nature. Even incorrect sorting of biodegradable plastic can contribute to leakage of plastic into nature.
- Food waste in Sweden is handled by local authorities and today treated generally by anaerobic digestion. As conditions differ between composting and an anaerobic digestion process, most plastics that break down in an industrial compost cannot be broken down by anaerobic digestion. The vast majority of compostable plastics on the market are not broken down by the conditions that apply in a home compost, it generally takes an industrial compost. In Sweden, there is currently no widely developed infrastructure for industrial composting.
Plastic may be called biodegradable if it does not break down completely- the standards required for packaging recyclable through composting and biological degradation (EN13432) allows a fraction below two millimeters (specified as “visually undetectable”). Incomplete biodegradation leads to microplastics and other synthetic degradation products.
If you use bio-based or biodegradable plastic
Think about this if you are considering using bio‑based or biodegradable plastic:
- It is still plastic. Some alternatives are incorrectly marketed as “plastic-free”.
- Biodegradable plastic often need industrial composting to break down. This needs to be stated in the information about the product. Industrial composting is today very unusual in Sweden, instead the food waste is treated through anaerobic digestion.
- Choose biodegradable plastic only if that function is needed for the product. Ask for information about conditions under which “biodegradable plastic” breaks down and investigate whether it is an advantage in your case. The best option with resource efficiency is material that is collected and material-recycled.
- The fact that a plastic is bio-based does not mean that it is biodegradable. Bio-based drop-in plastic works well in material recycling processes.
- Always declare how much of the plastic that is bio-based in the product! Often it is not 100 percent, which means marketing can be misleading for the consumer.
- Environmental performance of different bio-based plastics varies. Ask for information about the product’s environmental impact and choose raw materials and products with minimal impact on the environment.