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Bioplastics – Not a simple solution

Plastics made from plants have been around since the late 1800’s, but have only recently become widely used – generally in the form of a plastic called polylactic acid, or PLA.

Plastics made from plants have been around since the late 1800’s, but have only recently become widely used – generally in the form of a plastic called polylactic acid, or PLA. While many see bioplastics as a greener alternative to petroleum-based plastics, some waste-minimisation initiatives including those at the Otago Farmers Market and Gourmet Night Market would like to get rid of them entirely. Opposition to bioplastics has come as a surprise to some individuals and businesses that have begun to adopt bioplastic technology.

In the environmental realm, lots of things are seen in black and white – an action or a product is either good or it’s not. Bioplastics fall into a strange grey area where some promote the product and others decry it. Ultimately, bioplastics are a complex issue where some see potential benefits and others just see more waste. So let’s take a closer look at some of the pros and cons of this controversial material.

Plastic makes our lives much more convenient, but it takes a very, very long time to decompose. How long does it take, and do biodegradable plastics solve this problem?

First, some pros. Bioplastics like PLA are made without fossil-fuel based petrochemical products, instead being derived from renewable plant-based fats, oils and starches. Production of bioplastics requires considerably less energy input than traditional plastics (up to 65% less), and under the right conditions, the plastic polymers made from plants are able to decompose into just carbon dioxide and water. The product contains no toxins, and its production creates fewer greenhouse gasses.

While this all sounds like a giant step in the right direction, life-cycle analyses show that bioplastics have some caveats worth knowing about. The first has to do with the plants from which PLA is derived – mostly corn. In the US, industrial corn production uses more chemical fertilizer, insecticides and herbicides than any other crop. Akin to the ethanol debate, some also worry that growing corn for plastic takes up valuable land that could be put to better use growing food crops for our ever-increasing populace.

The second place where bioplastics meet with criticism is in the decomposition. Are bioplastics decomposable? Yes. But decomposition will only occur if the plastics are handled by an industrial composting system that has the ability to keep the compost at temperatures over 58 C for more than 2 weeks. Composting of bioplastics will not happen in your backyard, and won’t happen in most large-scale composting efforts such as those undertaken by councils. They require specially-managed composting systems that can add heat and carefully monitor temperatures.

Plastic is a ubiquitous and incredibly useful invention, but it has some serious downsides. But what if plastics were biodegradable? Tune in to learn more about the evolution and advantages of bioplastics.

Bioplastics can also be recycled, but only separately. As of now, not enough PLA is in use to make it worthwhile to recycle.  PLA is marked with a number 7 recycling symbol, which is the ‘all other plastics’ category. Bioplastics look very similar to conventional plastic and if they make their way into general recycling stream, become a contaminant – reducing the useability and lifespan of recycled products.

All this means that bioplastics aren’t quite yet the miracle material their manufacturers sometimes claim them to be. At this time, most recycling and composting programmes in NZ don’t have the facilities to properly degrade them back to natural components.  And so they end up in our already over-burdened landfills, where they are thought to take just as long to decompose as conventional plastics – somewhere between 100 and 1000 years.

We all talk about the Stone Age, the Iron Age and the Bronze Age, but what era are we living in right now? People are starting to refer to us as the – far less romantic – Plastic Age.

Problems like this are often faced by early adopters of new technologies. As more and more people choose bioplastics over conventional plastics, more councils and waste management companies may see the value of creating disposal systems that can handle them. But until then, people trying to do the right thing for the environment are caught in the tricky situation of using a biodegradeable product that doesn’t biodegrade.

Ultimately, though, if you pull back and look at the bigger picture, bioplastics support the continuation of our unsustainable throwaway culture. They make us feel better about the mountains of trash we individually produce. In an ideal world, we would find ways to eliminate single-use bags and containers entirely. Reducing and reusing are the most important pathways to a sustainable future. The less we throw away, the less we use and the less we need to produce. And in the long run, that’s the best way forward.


Contributor: Andrea Greene Liberatore

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