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Bioplastics are no more eco-friendly than conventional plastics

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Bioplastics create more problems than they solve

Environmental groups calling for recycling instead of bioplastics

Because of their durability, waste plastics constitute an undesirable but easily avoidable impact on the environment. Although packaging made of bioplastics presents itself as an eco-friendly alternative, the fact is that most of these products are detrimental to the environment and climate – during their production and their disposal.

Many people are alarmed by the increasing pollution of our environment caused by plastic waste. They are increasingly turning to products made from bioplastics as a supposedly better alternative: in 2018, 19 million tonnes of bio-based and partially bio-based plastics were produced worldwide, thus accounting for just under 6% of all plastics. It is expected that their share will increase to 10% by 2023. Most bioplastics come from Asia (55%), followed by Europe (19%) and North America (16%). South America, which itself produces comparatively few bioplastics (9%), supplies most of the raw materials that are processed into bioplastics worldwide. Sugar cane is cultivated on a large scale, especially in Brazil – mostly under catastrophic conditions for humans and the environment. Plants are renewable suppliers of raw materials, and it is true that they generally result in less greenhouse gas emissions than the processing of fossil raw materials into conventional plastics. But their cultivation uses vast amounts of water, fertiliser, agrochemicals and land: this means arable land for food production is lost or forests have to be cleared to provide new areas for cultivation.

‘Organic’ is not the same as ‘eco-friendly’

Most people are not aware of the devastating environmental balance of many bioplastics. As the general public’s perception of the term ‘plastic’ is negative, labelling something as being ‘organic’ is all the more popular. This is confirmed by a consumer study, which also revealed a frightening lack of knowledge on the part of those surveyed; the authors concluded that “people think that everything made from plants is eco-friendly”. In fact, the matter is more complicated. Those who buy fruit and vegetables in organic food shops are supporting a form of food production that does without artificial fertilisers and pesticides and thus makes a real contribution to the protection of species and the environment. Naturschutzbund Deutschland, a German organisation devoted to nature and biodiversity, criticises the term ‘bioplastics’ because it is “ultimately misleading, as they are not products of organic farming”.

Confusing variety of materials

The collective term ‘bioplastics’ covers the widest possible range of plastics that are characterised by certain properties: some are biodegradable, while others are bio-based, which means they are made entirely or partly from renewable raw materials; some bioplastics fall into both categories. However, this does not necessarily guarantee that these materials can be produced and disposed of in an environmentally and climate-friendly way. Take bamboo cups, for example: they are made of plant material and are therefore bio-based. But because they are supposed to be good as coffee cups and dishwasher-safe, the natural material is glued together with synthetic resins – and is then no longer biodegradable. Not to mention the harmful substances that, according to the German consumer organisation Stiftung Warentest, every second bamboo cup releases into a drink. A bamboo cup is a composite material, so it is not a mono-material and thus cannot be recycled. Consequently, it is even less sustainable than a pure plastic cup. 

Bogus label: biodegradable

Whether and how quickly a substance degrades and into which components it decomposes is determined solely by the chemical structure of its starting materials – regardless of whether these come from plants or petroleum. Take bio-PET, for example: although the ethanol required for its production is obtained from sugar cane, bio-PET is no more biodegradable than synthetically produced PET. In principle, plastics are considered biodegradable if they can be decomposed by microorganisms or enzymes. The crucial question is: how long does this process take in compost heaps, landfills or in the wild? Researchers at the University of Plymouth in England wanted to find out more and buried a number of bags made of organic and conventional plastics in the ground or submerged them in seawater. None of the bags had decomposed after three years, regardless of the material; for the most part, they were still in such good condition that they could carry a weight of more than two kilograms. The only exception were the bags made of compostable plastic: those buried in the soil had lost their load-bearing capability; those submerged in seawater had dissolved completely. 

Don’t put bioplastics in the brown bin or on the compost heap!

According to a European standard, bioplastics are ‘compostable’ if they have decomposed to water, carbon dioxide and biomass in industrial composting plants after 12 weeks. In an interview with the broadcaster Bayerischer Rundfunk, Michael Buchheit, chairman of a quality association for compost in the Erding administrative district, said, “Tests in actual plants have shown that even high-quality and technically well-designed plants do not manage to break down these bioplastics within the specified times.” The problem is that in almost all composting plants it only takes about six weeks for microbes to decompose bio-waste. It would therefore take twice as long for the adequate decomposition of compostable bioplastic bags – but that is usually not profitable for the waste recyclers. This is confirmed by a survey of about 1,000 composting plants conducted by Environmental Action Germany (DUH): 95 per cent of the plant operators said they cannot compost bioplastic products in accordance with the standards; bioplastics are therefore sorted out and incinerated, just like all other types of plastic. Consequently, as a basic principle almost all municipalities reject the disposal of bioplastics via the bio-waste stream. For the same reason, bioplastic bags do not belong in the brown bin – and certainly not on the compost heap at home, where they may take even longer to decompose than in industrial plants. 

Recycling instead of decomposing!

Scientists at the University of Hohenheim are working on bio-based plastics from plant waste, specifically those made from the roots of endives, of which around 800,000 tonnes are produced every year throughout Europe. The polysaccharide inulin can be extracted and processed into a bioplastic called PEF. An exemplary product: it is based completely on renewable raw materials, which are produced in a resource-conserving and eco-friendly way without the additional consumption of arable land, water, energy and fertiliser. Is it not possible to optimise this material so that it is also quickly and completely biodegradable? Quite possibly, but that’s not what matters to the researchers: “We don’t make biodegradable plastics, but recyclable ones. It is much more eco-friendly to reuse plastics than to compost them. And plastics that can be composted cannot be recycled,” explains Professor Andrea Kruse from the University’s Institute of Agricultural Engineering. Thomas Fischer of Environmental Action Germany also considers composting plastics to be undesirable, as he explained to Bayerischer Rundfunk: “Instead of senselessly disposing of energy-intensively produced plastics in the environment, we should try to actually use them materially and recycle them. And for that they don’t have to be biodegradable.”

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