What are bioplastics?

The use of bioplastics is widely discussed. Does it offer opportunities for producers and importers of packaged products within the framework of a circular economy or does it have more disadvantages than advantages?

The term ‘bioplastics’ is very broad, and is often used to describe several types of plastics, such as biodegradable plastics and bio-based plastics. These plastics all have different properties and characteristics and therefore different advantages and disadvantages. In this article, the different types of bioplastics are discussed in detail, and answers are given to frequently asked questions on this subject.

Bioplastics can be divided into two groups:

  • Compostable bio-based plastics
  • Non-compostable bio-based plastics

In addition, plastics made from fossil raw materials can be divided into two groups:

  • Compostable plastics (e.g. PBAT, PCL)
  • Non-compostable plastics (regular PE)

What does biobased, biodegradable and compostable mean?

The term bio-based only says something about the origin of the material from which the plastics are made. These plastics are made from natural materials, such as starch or sugar cane. The plastics are not biodegradable or compostable by definition.

Something is biodegradable when fungi and bacteria can break it down in a biological way, without leaving any residues. When a material is industrially compostable, it is biodegradable in the same way as materials which are home biodegradable. The difference between biodegradable and compostable is that with compostable there is a time limit. The degradation of the plastic strongly depends on environmental factors such as temperature, the presence of oxygen and water, and the presence of micro-organisms. Plastic is (industrially) compostable if it almost completely disappears within twelve weeks in an industrial composting plant with temperatures up to 65 degrees. The material is then broken down into water, methane and CO2. In nature this decomposition process takes much longer.

1 – Compostable bio-based plastics

Compostable bio-based plastics are plastics that are both made of natural materials and theoretically disappear completely in a composting plant. Examples include PLA, PHA and PBS.

PLA is one of the most popular forms of bioplastics and is made from lactic acid obtained from agricultural crops such as corn and sugar rue. It is used, for example, as packaging material for food products and for plastic drinking cups. It can also be used as ink for 3D printers. PLA is industrially compostable, only it takes much longer than VGF waste to compost. This means that when people throw it in the VGF waste it will remain when the VGF waste is already composted. It is then incinerated as residual waste. PLA does not perish on the compost heap at home either.

In principle PLA can be recycled, but not together with regular plastics. This can have a negative influence on the quality of the recycled plastic. It therefore must be collected separately and recycled in a separate recycling installation. At the moment this does not yet happen in the Netherlands because at the current low volume it is not interesting both in terms of cost and cost per environmental benefit. It is now incinerated together with residual waste with energy recovery.

2 – Non-compostable (partly) bio-based plastics

Non-compostable bio-based plastics are plastics that are made partly from natural materials, but that need to be treated like regular plastic. Examples are bio-PE, bio-PET and bio-PTT.

Based on production volume, bio-PET is currently the most common bio-based plastic. Bio-PET is partially bio-based polyester and has exactly the same chemical structure and properties as traditional PET. The material can therefore be very well implemented in products without causing problems for the current recycling streams.

Regular PET is produced by polymerization of ethylene glycol and terephthalic acid. To make today’s commercially available bio-PET, ethylene glycol is polymerized from bio-based raw materials with petroleum-based terephthalic acid. At the moment only 20% is bio-based, but this gives an environmental gain in terms of CO2 emissions and depletion of energy sources. In order to make 100% bio-PET, terephthalic acid must also be made from natural raw materials. This is possible, but very complex. Research now focuses on the development of more economic production routes and on up-scaling existing production routes.

3 – Compostable plastics (not biobased)

These are oil-based plastics that are compostable, such as PBAT, PCL and PVA. These plastics are a fully biodegradable alternative to low density polyethylene.

Recycling of bioplastics

Most bioplastics, with the exception of bio-PE and bio-PET, cannot be recycled with virgin plastics. This would have a negative impact on the quality of the recyclate.

However, certain bio-based plastics, including PLA, can well be recycled separately. There are a number of recycling plants that do this, but as explained earlier, this is not yet done on a large scale. Due to the current low volume, this is not interesting both in terms of cost and cost per environmental benefit. It is now incinerated together with residual waste with energy recovery.

Currently, much research is being done into the possibility of sorting PLA, for example, and what the costs, benefits and environmental benefits of this would be.

Composting bioplastics

There is a lot of uncertainty about the different types of bioplastics and how to deal with them. Many people think that all bioplastics are compostable. As explained above, this is not the case. And even when the bioplastics are compostable, there are still practical problems. At the moment, biodegradable plastic packaging does not belong with the GFT waste, even if it has a seedling logo or the OK Compost logo (see bottom paragraph). Only biodegradable plastic bags that are used in GFT collection are allowed with this waste, simply because it increases the collection of GFT waste.

 

Bioplastics that do end up in an industrial composting plant often remain as residual waste and are still incinerated. And if the plastics do compost on time, they reduce the quality of compost.

This was nicely illustrated in a recent episode of De Monitor. Many companies, institutions and organizations, including the central government of the Netherlands, invest a lot of money and effort in the purchase and separate collection of, for example, bio-plastic cups. The episode of The Monitor shows that this is immediately added to the residual waste, for the reasons given above.

It is striking that an even more recent study by Wageningen Food & Biobased Research (WUR) shows that compostable plastics can easily be processed in the current VGF waste processing process. This goes against all known practical examples so far. And this does not alter the fact that it lowers the quality of compost. In this sense, bio-plastics are also a source of pollution in this regeneration process.

The biggest misconception is that bioplastics decompose automatically when they end up in nature. Just like regular plastic, biodegradable plastic takes decades to decompose in the environment. And in the sea, this takes even longer than on land. It’s colder there, it doesn’t brew and there are no bacteria to break down this type of plastic. As a result, it causes just as much inconvenience in the sea as normal plastics. The stamp ‘biodegradable’ turns out to make people leave it in nature sooner, because they think it will perish anyway.

What are the advantages of bioplastics?

The great advantage of bio-based plastic products is that since renewable biomass is used no fossil raw materials are used. In addition, making bio-based plastics produces 50 to 100 percent lower CO2 emissions than other types of plastic. In principle, bio-based and biodegradable plastics can also be composted or recycled, provided this is done in an appropriate way.

What are the disadvantages of bioplastics?

A number of disadvantages have already been discussed above. For example, the fact that it does not compost fast enough and that it cannot be recycled together with regular virgin plastics. But the biggest disadvantage of bioplastics is the lack of knowledge of a large part of the population. If the products are not handled properly, it can disrupt current processes.

However, bioplastics offers many advantages. Research into new forms and applications is in progress. If the demand for bioplastics increases, for example due to environmental taxes on conventional plastics, this will lead to economies of scale. This can lead to efficiency gains in the production process and thus a falling price.

Which symbols are used to specify bioplastics?

Finally, some symbols by which you can recognize bioplastics.

The seedling logo and OK Compost logo have the same meaning. Products with this logo are industrially compostable. The logos are on bags, sleeves and trays made of compostable plastic. Only compostable bags (with the Sprouts Plant logo or OK compost logo) to collect your VGF may be placed in the VGF bin. Other compostable packaging and compostable products must be disposed of with the residual waste. It is not clear whether the lead time in the industrial composting installation is long enough for compostable plastics to decompose properly within that time. The packaging should also not be placed on the compost heap at home, as such materials do not decompose there either.

The OK Home Compost logo guarantees that the product is suitable for composting at home.

The OK biobased logo indicates whether a product consists of renewable materials. It has four levels, from packaging that consists of a minimum of 20 percent (one star) to packaging that consists of a maximum of 80 percent (four stars) of renewable materials. The logo doesn’t say anything about the compostability of the packaging.

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