Do you know the difference between compostable, biodegradable and bio-based plastics?
The evolving world of alternative plastics
In the wake of the Blue Planet Effect, the world is on a plastic detox. From petitions for plastic-free supermarkets to the world’s first plastic-free aisle, the war on plastics is on. UK businesses are also jumping on the bandwagon, with more than 40 companies recently signing the new Plastics Pact to eliminate single-use packaging.
Are you also reconsidering conventional plastics? Navigating the landscape of alternatives can be confusing. Should you switch to bio-based, biodegradable or compostable plastics? Don’t let the many buzzwords leave a looming question mark around the possibilities for your business.
Use our blog to test your understanding of key differences between alternatives and avoid misconceptions!
Common convictions around plastic alternatives
“Biodegradable always means compostable”
False: These two terms are often used interchangeably but are not fully synonymous. Compostable plastics are always featured, biodegradable, but the opposite doesn’t hold true.
In theory, biodegradable materials should break down into carbon dioxide, water and minerals. Considering many plastics take centuries to break down, it’s not surprising that this seems like the antidote to our plastic addiction. Here’s the catch: many things on the planet biodegrade but most plastics only do so at specific temperatures and optimal levels of water, light and oxygen. Even so, some biodegradables still leave toxic residues in the environment.
Compostable plastics break down without leaving any traces of toxic waste. Composting is essentially a way of allowing plastics to biodegrade into high-quality fertilizer.
But not all compostable plastics are created equal. While some are compostable at home, most will only break down in higher temperatures that can only be reached in industrial facilities.
In practice, most plastics that are labelled “biodegradable” are only compostable in industrial facilities – not at home nor in the environment. Look out for the compostable seedling logo – it certifies that a plastic is industrially compostable. You may also come across the OK Compost home certification, although it’s far less common.
False: Bio-based plastics can be: conventional plastics, biodegradable but not compostable, or biodegradable and compostable.
Bio-based plastics, or ‘bioplastics’, are made from at least 20% of renewable feedstocks. Some bioplastics are chemically identical to standard plastics and therefore, rather confusingly, these are non-biodegradable but are recyclable. Bioplastics are often used in the production of widely recycled conventional polymers, such as PET.
That being said, over half of biodegradable plastics on the market are bioplastics made from corn, coconut, potato, rice, soy proteins or sugarcane. These “starch-based” plastics are usually compostable. Some are also blended or layered with petroleum-based plastics and additives to help decomposition.
“All alternative plastics can be composted”
False: Each type of alternative plastic has an optimal disposal route. While some are best disposed of through composting or anaerobic digestion, others are designed to be mechanically recycled.
- Biodegradable bio-based plastics are usually industrially compostable. Some can also be sent to anaerobic digestion facilities, where microorganisms break down the organic material. The process releases biogas and produces a residual material called digestate – both of which are can be used as inputs for industrial composting. Likewise, biodegradable petroleum-based plastics can be industrially composted, but few can be anaerobically digested. Home compostable plastics are rare and only a handful of bioplastics will make the cut.
- Non-biodegradable bioplastics, such as bio-PP, bio-PE and bio-PET, are chemically identical to their petroleum-based counterparts. All of these can, therefore, be thrown into the same recycling bins. Unfortunately, other non-biodegradable plastics are often too costly to recycle due to small volumes.
“The benefits of alternative plastics are hindered by misconceptions and the slow emergence of adequate infrastructure”
True: The General public is no plastic expert. Even those who are aware of optimal disposal routes, don’t always have access to them.
Misconceptions can compromise a successful transition to alternative plastics. If all alternatives are assumed to be compostable anywhere in nature, we won’t solve plastic littering.
A large percentage of “biodegradable” or industrially compostable plastics still end up in our oceans. Have you ever heard of a 50°C to 70°C ocean? The sea is simply not suited for these plastics to biodegrade, which means impacts on aquatic life remain.
Spotting the difference between plastics is difficult. A few years ago, Coca-Cola made a bold effort to reduce their reliance on petroleum by switching their bottles to a bio-based plastic. But people got confused by how to dispose of the new PlantBottle as it looked so similar to a standard plastic bottle.
Can you tell the difference between conventional and bio-based PET?
Chemically, these two bottles are essentially identical. Though the PlantBottle is made with up to 30% bio-based ethanol, it does not biodegrade. Instead, it’s designed to be recycled. Unfortunately, the world has a limited number of chemistry graduates. It’s easy to assume that the tiny green PlantBottle logo means: “I’m made of plants, so throwing me in nature is fine because eventually, I’ll disappear”.
Consider another scenario: you want to dispose of a compostable fork. It looks and feels like plastic, so shouldn’t it be recycled? Unfortunately, biodegradables cannot be recycled. If mixed with other recyclables, they will contaminate all other materials and prevent anything from being recycled.
A large gap in available infrastructure for biodegradables also remains. Food waste collection in the UK is in its infancy.
Considering most people don’t home compost or have access to food waste collection, compostable plastics usually end up in general waste bins. As with other organic material, this will eventually lead to potent methane emissions as the waste breaks down in the landfill.
Overcoming the challenges associated with misconceptions and infrastructure is difficult. Being equipped with an understanding of the differences between bioplastics, biodegradables and compostables is a great place to start. If you are considering transitioning to an alternative, these three key takeaways will further help guide your business towards more effective solutions:
Key takeaways for your business
Consider available infrastructure
Understanding where your plastic packaging ends up is crucial. Where are your customers likely to dispose of it? Prior to designing your packaging and choosing an alternative plastic, establish whether the infrastructure to dispose is available to your customers. Gaining insights on available disposal routes will ensure that you choose the most appropriate and impactful solution. For example, it is more sensible to use a bio-based plastic that fits into existing infrastructure, than to switch to biodegradable plastics where composting infrastructure is unavailable.
Think about design
Having considered available infrastructure, you can begin to review your use and need for plastic packaging. Where can you minimize the amount of packaging used? Where can you increase the recycled content? Are there plastic alternatives that meet the design credentials you need? If you do choose to pursue a suitable alternative, you should also ensure the packaging is designed in a way that clearly tells customers how to dispose of it.
Communicate with your consumers
Customers need guidance. Companies that want to lead by example cannot overlook the role of educating the general public. Confusion leads to inefficiency, as mistaken materials end up in the wrong waste streams. Establish a strategy to ensure customers understand what your packaging is made of and how to dispose of it. If it is non-biodegradable but recyclable, make it obvious. Likewise, people need to understand how to optimally dispose of biodegradable plastics to avoid contaminating recycling streams.
You may also be interested in learning about the solutions to plastic pollution at different lifecycle stages of plastics. Read our post here ‘We have a problem and a lot of plastics’.
Are you still not sure how to address your plastic packaging? Get in touch, Carbon Smart can help you undertake a packaging review and establish a sustainable packaging strategy.
Upcoming feature: Feasibility study on compostable plastics in the UK.