Bioplastics: A Plastic Revolution or a Load of Rubbish?

Guest article from City to Sea and their Refill Campaign. Find out more about how to move away from single-use plastics and join the #RefillRevolution here.

A takeout cup holds a bunch of drinking straws labelled compostable with the sea in the background

While bioplastics might sound good, they are still a single-use material with extremely limited options to compost them. If compostable plastics are to become a viable alternative to oil-based plastics, there is a lot of work for the bioplastics and waste industries to do so they can better work together…

Compostable bioplastics have been touted as the solution to our single-use, throw-away lifestyle, allowing consumers to enjoy takeaway coffees guilt-free.

But the issue of bioplastics is complicated – not only for consumers, but also for many small businesses that have been trying to do the right thing by making the switch from plastics to bioplastic alternatives.

Although interpreted and sometimes marketed as such, compostable plastic takeaway packaging wasn’t actually designed to be the solution to plastic pollution. In reality, it was designed to prevent food waste being contaminated with plastic packaging, as one of the original compostable packaging producers, Vegware, explains here: “Whilst Vegware’s plant-based disposables are designed to replace oil-based plastics in a foodservice setting, compostable packaging is not the solution to marine pollution”*.

What are the Differents Types of Bioplastic?

To be called a bioplastic, a product has to be either biodegradable or made from plant-based materials. But being made from a plant doesn’t mean a product will degrade like a plant, and being biodegradable doesn’t mean a product will break down with food waste in the kitchen. In reality, most bioplastics need to be composted at very high temperatures over several weeks in an industrial composter.

The phrase ‘biodegradable’ is often used in connection with bioplastics, but this can be misleading because most of us think biodegradable means what happens to an apple core in the ground. Instead, for a bioplastic to be described as biodegradable it needs to pass the EN13432 test for industrial composting – so not at all like an apple core!

Compostable plastics (commonly labelled as PLA)

A polylactic acid derived from the sugar and starches of plants, most commonly corn starch and sugar cane. PLA is the clear bioplastic often used in salad and deli food boxes and as a liner in coffee cups and sandwich boxes. PLA will break down within 90 days in an industrial in-vessel composter running at 60 degrees. In order to be compostable it has to be tested and meet the criteria of EN13432.

Compostable plastics (commonly labelled as PLA)

A polylactic acid derived from the sugar and starches of plants, most commonly corn starch and sugar cane. PLA is the clear bioplastic often used in salad and deli food boxes and as a liner in coffee cups and sandwich boxes. PLA will break down within 90 days in an industrial in-vessel composter running at 60 degrees. In order to be compostable it has to be tested and meet the criteria of EN13432.

Oxydegradable plastics

These are sold as bags and straws and are really petroleum-based plastics that break down into lots of little pieces. Yes, that’s right, they’re actually designed to turn into microplastics – not as earth-friendly as they sound! The EU Environment Committee is demanding a ban on these by 2020. And quite rightly so.

CPLA 

Like PLA but with added chalk. CPLA is used to hold food products that need to tolerate high heats: things like cutlery, coffee–cup lids and dishes for serving hot food. As with PLA, it needs to be broken down in an industrial in–vessel composter.

What about New Materials?

New materials are being introduced all the time, such as cassava root and thistle starch bags, or water-soluble bioplastics made from seaweed. But with all these materials it’s important to understand how long they take to degrade and what conditions they need. Sadly, most plastic packaging that ends up in a food waste bin will get pulled out for incineration before it has even had a chance to break down.

Non-compostable bioplastics

Hemp and sugarcane have been used to mimic the structure of fossil fuel-based plastics. These bioplastics are used for applications such as car parts or water bottles. Green HDPE is made from sugarcane and can be recycled like HDPE.

Water-soluble bioplastics 

Made from seaweed. These bioplastics are used to make drinking balls such as Ooho balls that were trialled at the London Marathon 2019, and are also being developed in Indonesia for washing liquids and food sachets which break down in water.

To Bin or not to Bin

The second big issue is that we don’t currently have significant infrastructure to compost bioplastics in the UK. The industrial composters that can break down compostable plastics are called in-vessel composters and there are currently only around 18 in the UK. These sites only accept waste that’s guaranteed not to be contaminated by oil-based plastics, which means the shipments need to come from closed environments (like festivals) which can guarantee the plastics have been kept separate. Some café’s are offering take-back schemes to enable this too.

This leaves us consumers in a plastics pickle. Compostable bioplastics look exactly the same as oil-based plastics, so they often end up in the food bin or the recycling bin when actually, the only household bin they can go in is the general waste bin. Yes, that’s right, we’re expected to understand that ‘compostable’ doesn’t mean we can actually compost them. As clear as mud.

A Load of Rubbish?

What all this means, is that while bioplastics might sound good, they are still a single-use material and there are extremely limited options to compost them. Ultimately, due to the nature of when we tend to use bioplastics – as take–away food containers and packaging – they end up in the bin and consequently in landfill. The other issue is that as they don’t biodegrade outside of certain conditions, they can still contribute to marine pollution if they become litter.

If compostable plastics are to become a viable alternative to oil-based plastics, there is a lot of work for the bioplastics and waste industries to do so they can better work together.

Our advice at City to Sea remains that refusing plastic and any single-use is the only solution. So choosing to refill and reuse are the best options. If your local cafe is using bioplastic packaging, then treat it as you would traditional plastic and take your own reusable alternatives.

Everything you Need to Know about Bioplastics

If the bioplastic items are home-compostable and you have a compost bin in your garden, put them in there. Otherwise, any compostable plastics need to go in your general waste bin. This will mean they will go for waste to energy incineration or landfill.
Unfortunately not. Most household food waste is composted at anaerobic digester plants, which work without heat or oxygen and can’t break down solid packaging like your compostable food bag. This means any packaging gets pulled out for waste-to-energy incineration.
The company Vegware is working on a couple of schemes to get ‘their’ compostable plastics to a composting facility that will accept them. The Composting Collective supports large institutions and cafés to get their packaging to a local in-vessel composter, at a cost. For individuals they have a post-back scheme, so people pop their materials in a box and return at a cost to the individual of £20.
But these two schemes are only for Vegware products as these are the ones that the composting facilities have approved, as many others don’t breakdown as well as they claim to.
No, they are designed for composting, not recycling. PLA has a number 7 on the bottom which may lead you to believe it is recyclable – but it isn’t. Don’t be misled! The number 7 is for ‘other materials’ which are not recyclable, so they shouldn’t go in the recycling bin.
At present, plastic recycling facilities haven’t started using the technology enabling them to differentiate between PLA and PET plastic, as currently there are not high enough volumes of compostables to justify investing in it.
There are concerns that bioplastics will reduce the quality of oil-based plastic recycling, as the polymers and materials are different. However, it has been suggested by some studies that the volumes of compostable materials getting into the recycling waste stream are still low.
German and Italian studies have suggested that recycled content would not be affected by up to 3% PLA in Polypropylene (PP), and 1-2% in recycled PET.
Unfortunately, the conditions aren’t hot enough. Plus no waste decomposes in a landfill, because of the combinations of materials compacted on top of each other. So even compostable plastics will remain as they are in landfill, like the rest of the waste.
Many people have asked whether compostable plastics give off methane in a landfill like other organic materials. The answer is no because they need to reach 60 degrees before they start decomposing, so they just remain inert.
The EU is planning to ban problematic bioplastics, like oxydegradable ones, and the EU single-use plastics directive which is calling for a sustained reduction in single-use materials includes bio-based and bioegradable plastics With Brexit, it is not clear if the UK will adopt this or how the Waste and Resources Strategy will legislate against bioplastics. The strategy has taxes planned for packaging that is difficult to recycle and doesn’t contain 30% recycled content, although there is also the mandate that by 2025 all plastic packaging should be reusable, recyclable or compostable.
Yes, that’s true. They do generally have a lower carbon footprint, although they have other environmental impacts that plastics don’t have from the crop production. There are concerns that increased demand in the market will lead to crops being grown for bioplastics, as has happened with biofuels. However, according to most of the producers of compostable plastics, corn starch and sugar cane ethanol is extracted as a by-product of the crop production, so the crop is being harvested for multiple purposes, e.g. corn for animal fodder and sugar cane for sugar.
One of the issues with these materials is that they can’t be certified organic or GMO free because of the crops they’re derived from. Another issue is that if they become litter, they could still harm animals as they won’t degrade if they become litter.
Home compostable and industrially compostable packaging will remain intact if it becomes litter in the street or on a beach. It will also stay intact if it ends up in rivers or the sea, because it needs to be in a composting environment that gets hot in order to decompose.
New bioplastics are being created all the time. For instance, in Brazil they have developed a green-HDPE that mimics the plastic HDPE polymer (used for making milk bottles and hard plastic drink bottles) and can be recycled in the same way as plastics.
There are also salad bags made from thistle-starches which are GMO free and suitable for home composting. However, if these go in the food caddy it is most likely that they will get pulled out at the depackaging stage of a composting facility unless they degrade quickly on contact with water.
In Indonesia, bioplastics are being created from seaweed, to tackle the issues of small sachet litter. The sachets can be used with their contents e.g. drink sachets can be put in hot water along with their contents. If used for washing powder, they will degrade in the washing water.
All single-use items contribute to a production cycle of continuous manufacture, transportation and waste disposal. They require energy, water and chemicals, creating greenhouse gases and industrial waste. This is true of both compostable and ordinary plastic. Plastic that can be reused – of whatever sort – only contributes to this cycle once in its lifetime. We strongly believe in reusing products rather than buying new ones.
A Life Cycle Assessment comparison study of compostable bagasse (sugarcane fibre rather than PLA) burger boxes with reusable containers was carried out at the University of California. They found that a reusable polypropylene (plastic) container would need to be used more than 15 times to have lower greenhouse gas emissions, energy and waste impacts than a compostable one.