Plastics are an increasingly big problem for our planet. They consist of increasingly scarce petroleum, quickly end up in the trash, cause emissions during production and burning and, if disposed of improperly, pollute the environment. So-called bioplastics are intended to counteract the problems. What makes these materials “organic”? And how environmentally friendly are they really?
Plastic is ubiquitous and has a bad reputation. The petroleum-based material pollutes the environment and at the same time it is hard to imagine our everyday life without it. Bioplastics are intended to provide a solution: They should replace fossil raw materials, protect the climate and, in the best case, even be able to decompose more quickly. However, the “organic” in bioplastic is not the same as the term organic as we know it from food.
“Sweet” plastic
Bioplastics can be divided into two categories: bio-based and biodegradable. Bio-based plastics consist entirely or partially of renewable raw materials such as sugar cane, vegetable oils, cellulose or starch. They can replace petroleum as a fossil resource, but in some cases they last just as long as conventional plastic. Regardless of their composition, biodegradable plastics must decompose almost completely according to the standard – but often only under specific conditions such as high temperatures in composting plants.
A particularly common example of bio-based plastics is bio-PET, which usually consists of around 30 percent sugar cane. Bio-PET has the same product properties as classic PET and can therefore be easily integrated into existing production and recycling systems. This so-called “drop-in” solution is attractive for manufacturers because they do not have to develop new processes.
Production of bioplastics is not always sustainable
Although bio-based plastics such as bio-PET save fossil resources, their production can have a significant impact on the environment. This is particularly evident in the raw material sugar cane, which is cultivated extensively in tropical regions. Such monocultures, in which only one type of plant is grown over a long period of time, endanger animals and plants. Large amounts of water and fertilizers are also required, which puts a strain on ecosystems. Environmental associations also criticize that the many sugar cane fields sometimes displace small farmers, who then move to forested regions, which also indirectly endangers the rainforest.
Further processing of bio-based raw materials such as sugar cane in refineries is also energy-intensive and leads to emissions. Although plants bind CO2 as they grow, this advantage is partially offset by agricultural and industrial emissions. The ecological balance of bioplastics therefore varies greatly depending on the raw material and production method.
Burn over rot
Another problem arises when it comes to disposal. Because bioplastic is often no more degradable than conventional plastic. Since both variants of bioplastics can hardly be distinguished from conventional plastic on the outside, even biodegradable bags often end up in residual waste – for example because employees in waste disposal companies cannot reliably identify and sort them out. Many composting plants also sort out organic materials as standard because they take too long for the short composting cycles in industrial plants. This means that even compostable plastic is usually burned in the end.
If the bioplastic waste makes it into the composting plant, problems can still arise: Many plants only leave the biowaste for six to eight weeks, even though it often takes longer to decompose. According to the standard, bioplastics can take up to twelve weeks to decompose. However, if this waste is only partially composted, the remaining larger parts will disrupt the compost.
Completely decomposed bioplastics do not cause such problems, but they also offer little benefit: they provide neither nutrients nor humus. However, some of the decomposed bioplastic can be used again to make new plastic. If such recycling is not possible, the Federal Environment Agency recommends using the bioplastic for energy: When burned, the waste at least generates energy again in the form of electricity and heat.