Explore the promising but problematic world of bioplastics
Fifty-plus years after the release of The Graduate, it’s hard not to cringe watching the famous scene of Mr. McGuire offering Benjamin a “great future” in plastics. We now live in the movie’s future, and a staggering quantity of petroleum-based plastic chokes our oceans, leaches toxic chemicals into the ground, and threatens the health of countless organisms—including us. Enter the multitude of (relatively) new alternatives to traditional plastic: bioplastics.
The term “plastic” applies to any moldable synthetic substance made from organic polymers (chains of chemically similar units). “Bioplastics” is a blanket term referring to a wide and potentially confusing variety of plastics that are either biodegradable, bio-based (derived from organic matter), or both. Proponents champion them as being more eco-friendly than conventional petroleum-based plastics. Critics argue that most bioplastics come with their own environmental complications.
Imagine you’re buying a bottled drink. For the sake of this thought experiment, your personal travel mug isn’t available; neither are glass bottles. However, your favourite beverage comes in three different bioplastic bottles of the same size. Here’s what you know about each.
Bottle A is made from corn and is compostable at an industrial composting facility (but not in your back yard). The bottle itself is carbon neutral. However, the farming operations that produced the corn are not. The corn crops also take up land that might otherwise be used to grow food. If you throw Bottle A into a conventional plastic recycling bin, the entire lot could be rejected and sent to the landfill.
Bottle B is labelled “plant-based.” It’s a mix of petroleum- and plant-derived polymers and is chemically identical to a traditional plastic bottle. Because of its content and production process, the bottle is not carbon neutral. You can throw it into a regular plastics recycling bin; however, if it ends up in the landfill or the natural world, it will take just as long to break down as regular plastic.
Bottle C contains bioplastic that has, remarkably, been generated by micro-organisms that consume food waste. When you’re done with it, this bottle can be composted anywhere or safely discarded. If it happens to end up in the natural world, bacteria will break it down into water and carbon dioxide. If, however, you throw it into a regular recycling bin, it will be identified as “other material” and rejected. Because of Bottle C’s production costs, the drink inside is considerably more expensive than the others.
So … which of these bottles, if any, do you choose? For many of us, there’s no perfect answer.
If this small sample of the various bioplastics out there seems confusing, many experts would concur. Karen Wirsig, plastics program manager at Environmental Defence, argues that the informational “cacophony” associated with bioplastic products and technologies diverts our attention away from the serious environmental problems connected to plastics of all kinds.
This lack of critical awareness, she believes, is further enabled by the “greenwashing” of many bioplastics and the short-term commercial interests of most producers of bioplastics.
Asked about the potential benefits of bioplastics, Wirsig identifies a number of conditions that must first be met before bioplastics can play a positive and sustainable role in our world. For any given use, she says, we need to “take a step back,” consider all the plastic-free alternatives, and assess whether or not plastic—bio or conventional—is indeed the best option.
In those situations where it is, there must be infrastructure and regulations in place to ensure the plastic is safely and sustainably dealt with at the end of its life.
Professor Gadi Rothenberg, a bioplastics expert and Chair of Heterogeneous Catalysis & Sustainable Chemistry at the Van’t Hoff Institute for Molecular Sciences (University of Amsterdam), is more enthusiastic about bioplastics.
He believes that, despite their inevitable shortcomings as an emerging technology, bioplastics “have an important role to play …, especially in the transition from our current ‘produce-use-waste’ economy to a circular economy.” In addition to their intrinsic value, Rothenberg says that “bio-based materials have a strong educative value, as they demonstrate … the importance of changing the way we live.”
For his part, Paul Antoniadis, CEO of Good Natured Products (a producer of both commercially compostable and conventionally recyclable bioplastics), stresses that he and his team are “big believers in reuse and recycling.” At the same time, he says, the demand for single-use packaging—particularly in a world affected by the COVID-19 pandemic and a heightened attention to food safety—is “unlikely to disappear anytime soon.”
Antoniadis maintains that his company focuses on having its products do less harm by “reducing reliance on fossil fuels, removing chemicals of concern, and providing for multiple end-of-life options.”
Environmental scientist Abdul Khogali, COO of Genecis Bioindustries, echoes Antoniadis’s remarks when he observes that “consumer behaviour is hard to change, and the market for [disposable] materials will not disappear in the short term.” In the face of this challenge, Khogali and his colleagues have focused on producing plastics that will fully and readily degrade in “any environment.”
Genecis plastics are PHAs (see “The ABCs and Ps of plastics”), a form of bacterial energy storage. While Khogali acknowledges the current high cost of exploiting this natural mechanism, he’s also optimistic that cost-reduction strategies, such as using organic waste to feed the PHA-generating bacteria, will lead to cost-competitive products. His goal is to create a plastic that frees us from having to “choose between functionality, sustainability profile, and cost.”
In the meantime, we are still in a position of needing to make difficult choices when it comes to plastic in our everyday lives. Ideally, our choices should be as well-informed as possible. And, to return to that hypothetical bottle scenario, remembering to pack your own travel mug is probably the best choice.
PLA (polyactic acid) is one of two main subsets of bioplastics. Made from chemically processed plant sugars, it shares many of the physical properties of PET. It is biodegradable, under specific conditions. (See “Bottle A”.)
PET (polyethylene terephthalate) is plastic derived from crude oil and natural gas. Its proponents argue that it is lightweight, reusable, widely recyclable, and minimally dependent on world oil supplies. “Bio-PET” is chemically identical to PET but contains a variable percentage of plant-derived ethanol. (See “Bottle B.”)
PHA (polyhydroxyalkanoate) is the other main subset of bioplastics. It is the stored carbon (energy) produced by bacteria as they consume organic material. It is biodegradable. (See “Bottle C.”)
The degrading, or breaking down, of plastics is a crucial feature of their sustainability profile. Here are some key terms to know.
Biodegradable Plastic is considered biodegradable when it can be broken down by bacteria into water, carbon dioxide, and compost, within weeks to months, under suitable conditions. Not all bio-based plastics are biodegradable.
Compostable Some biodegradable plastics are also compostable (a narrower category). These plastics will break down in a compost pile at the same rate as regular organic matter, leaving no toxic residue.
Oxo-degradable Plastics bearing this label are treated with a chemical that causes them to break down rapidly into microplastics. Unlike biodegradation, this process does not involve molecular change. If the plastic is deprived of oxygen (in a landfill, for instance), it could release methane, a more potent greenhouse gas than carbon dioxide.
No matter how eco-friendly their construction materials and methods might be, plastic packages and containers come with environmental costs. Check out Beth Terry’s myplasticfreelife.com or Kate Nelson’s iquitplastics.com for a wealth of ideas and resources for reducing the amount of wasteful packaging in your life.