by Sophia Reißenweber, Amon Zänker & Charlotte Bolinski

In which area of application do they currently see the greatest potential for bioplastics as a substitute for petroleum-based plastics? 

In general, we take a critical view of the use of bioplastics. A distinction is made between „biobased“ and „biodegradable“ bioplastics. Biobased plastics are not always biodegradable and vice versa. From comparative life cycle assessments of simple objects and packaging, we know that the environmental impact is not significantly improved if the raw materials are biobased instead of fossil-based. The effects tend to shift: While conventional fossil-based plastics release more climate-impacting CO2, the ecological footprint of biobased plastics manifests itself in a higher acidification and eutrophication potential as well as a certain amount of land use. The reason is the agricultural production of the raw materials. There may be competition for land with food production or compensation and forest areas may become less. To ensure that valuable resources can be recycled and thus save resources, only those bio-based plastics should be used that have the same properties as recyclable plastics. If bio-based and fossil-based plastics have the same structure, these bio-based materials are called drop-in plastics. This can be, for example, bio-based polypropylene (Bio-PP), which has the same properties as fossil-based PP, or bio-based polyethylene terephthalate (Bio-PET), which has the same structure as conventional PET. Here, a recycling structure already exists so that Bio-PP and Bio-PET can be recycled together with the structurally identical PP and PET of fossil origin. However, this is not the case with bio-based plastics, which have a different structure than conventional plastics; they cannot be recycled. So far, they are only used for energy recovery and are therefore not recommended from this point of view. 
Biodegradable plastics offer no ecological advantages. First of all, biodegradability means a waste of resources, as the materials are produced in a costly manner and are then lost to the circular economy through composting or energy recovery. This is because they cannot be recycled. Furthermore, the composting of biodegradable plastics mainly produces CO2 and water, which do not make a significant positive contribution to the formation of humus. In addition, products made of biodegradable plastics must be disposed of as soon as they become waste, either via the residual waste fraction or, in the case of packaging, via the yellow bag/yellow garbage can (lightweight packaging collection). In both cases, they are energetically recovered (by combustion). Only certain biodegradable biowaste collection bags (standard EN 13432) may be disposed of via bio-waste collection in accordance with the Biowaste Ordinance. Bio-waste collection bags bear a danger of confusion with those made of non-degradable plastics, therefore in most composting plants all collection bags must be sorted out. The degradation time specified in the EN 13432 standard, according to which e.g. bio-waste collection bags are certified, turned out to be a problem, as the treatment times in today‘s composting plants in Germany are significantly shorter. The biowaste collection bags did not decompose completely despite being degradable according to the standard. However, manufacturers have now reacted and developed material with shorter degradation times. Nevertheless, it is possible that particles, e.g. from knotted bags, can still be found in the finished compost. It can be assumed that packaging and products made of materials certified according to EN 13432 have a much higher wall thickness than the biowaste collection bags now adapted to composting plants. So if, contrary to the legal requirements, biodegradable plastic products and packaging are added to the biowaste and not sorted out in the composting plant, the retention time of 4-6 weeks in composting plants is not sufficient for degradation. Products and packaging made of biodegradable plastics may not be disposed of in the environment and pose a risk there just like other plastic products. The degradability of biodegradable plastics in the environment depends strongly on various factors such as material thickness, type of material, temperature, humidity and microorganisms and is currently being investigated. So far, however, it can be assumed that degradation in the environment takes much longer than under the optimized conditions in composting plants. Some biodegradable plastic films were not even degraded after two years in studies. 
Single-use products and single-use packaging made of biodegradable and/or bio-based plastics, in contrast to reusable packaging and products, generate unnecessary waste and may encourage careless handling of waste (e.g. disposal in the environment). 
Applications for biodegradable plastics in forests, gardens, agriculture and fisheries could be advantageous in cases where the products are necessary but cannot be recovered from the environment. Degradability could offer an advantage if the products that are introduced into the environment but cannot be retrieved because of their function are otherwise made of non-degradable, conventional plastics. For this purpose, however, the degradability of the products concerned should be optimized from biodegradable plastics, the previous degradation times should be further reduced and scientific test procedures should be developed and carried out directly in different environmental media and conditions. 

How can companies be motivated to switch to biobased plastics? Is the social pressure already sufficient or is it time for political action? 

The demand of consumers for (apparently) more ecological products seems to influence the product development of companies at least partially. We see a need for further research on the ecological advantages of bioplastics. Therefore, we do not advocate political action at present. It is not possible to give a blanket answer as to whether packaging is environmentally friendly. Packaging and unnecessary products should be avoided as a matter of priority. Unfortunately, the consumption of single-use packaging and products continues to increase. If, on the other hand, packaging is used several times, each cycle of use avoids waste. Reusable systems are essential to avoid packaging waste. As a scientific authority, we conduct research on numerous aspects of packaging avoidance and advise the German Federal Ministry of the Environment on possible courses of action. For example, starting in 2020, we are having a research project investigate ways of promoting existing reusable packaging systems and what potential for new reusable packaging can be exploited along the supply chain and in the retail sector. If packaging is necessary, there are various aspects that play a role in addition to the most frequent possible reuse. Packaging should be designed to be as little complex as possible and not material-intensive to avoid unnecessary waste of packaging material. Therefore, packaging should be adapted to the size of its contents as needed. From the point of view of the German Environment Agency, it is essential that packaging can be recycled to a high quality after use in order to keep the recyclable materials in the cycle. How the recyclability of packaging can be determined is shown by a minimum standard for determining the recyclability of packaging subject to system participation developed by the Central Agency Packaging Register and the German Environment Agency. It is becoming apparent that this minimum standard will also establish itself as an important orientation for packaging manufacturers. 

From 2021, new, Europe-wide guidelines will come into force, including for single-use plastic products. How do you think these directives should be implemented in Germany?

Plastics in the environment have been given measures by the EU. This concerns the single-use plastic products most frequently found on European beaches. The EU directive 2019/904 on the reduction of the impact of certain plastic products on the environment (Single-use plastics directive, SUPD) came into force on July 3, 2019. Under this directive, member states are obliged to implement various measures in national law by July 3, 2021. The SUPD also addresses single-use plastic products made of bio-based and biodegradable plastics and therefore these are subject to the measures specified in the directive. This therefore also applies to the implementation of the EU SUPD in Germany. In the search for alternatives, reusable products and packaging are the best choice. The release of waste into the environment must be avoided at all costs and waste must be removed from the environment. Waste from biodegradable and/or bio-based plastics is no exception. 

What role does the collaboration of designers and scientists play for them in the context of recycling management? 

 The cooperation between designers and scientists, but also between all other actors involved in the circular economy is very important. Because the course for recycling must be set as early as the product design stage. If possible, products should be designed in such a way that they have a long service life and can be reused after an utilization cycle. In addition, products should be able to be recycled to a high standard. For example, designers must know which materials can be used for certain applications in order to meet these criteria. In addition to being recyclable, products should also be made from recycled materials, as this is the only way to ensure that materials can be recycled. See also the „Leitsätze einer Kreislaufwirtschaft“ (Guidelines for a recycling economy) published by the German Environment Agency, in particular Guideline No. 7. 

Sonia Grimminger is a research assistant at the German Environment Agency (UBA). The research and consulting focus of the M.Sc. chemist is the avoidance of packaging and disposable products. Among other things, she deals with the promotion and optimization of of reusable packaging systems as well as an ambitious implementation of the EU directive on single-use plastics. 
Jasmin Boße is a research assistant at the German Environment Agency (UBA). The research and consulting focus of the M.Sc. environmental engineer is on bio-based and biodegradable plastics, recycling of packaging and the use of recycled materials.

German Environment Agency (UBA)