February 12, 2020

Why compostable plastics aren't such a great idea

Don't jump on the compostable packaging bandwagon — it's not quite what it seems.

Claire Rampen

5 min read

No-one needs to remind you that packaging waste is a problem; even if you missed the harrowing scenes in the BBC’s Blue Planet, it’s hard to avoid the many stray bottles and crisp packets that whip across your path on a windy day in London or Paris. Where other types of pollution may be “invisible”, we are faced with daily evidence of this broken system. 

It’s no wonder that ambitious and optimistic startups (like Finland’s Sulapac, Italy’s Vegea or Scotland’s Vegware) are jumping on this as a problem to solve. What the packaging industry may lack in sex appeal, it makes up for in ubiquity and market size; valued at $917bn in 2019, and forecast to reach over $1tn globally by 2024. 

Finnish packaging startup Sulapac's compostable straws.

So, when you see headlines like “I invented a plastic alternative from fish waste!”, it’s hard not to get excited — is this the silver bullet to pragmatically tackle our society’s addiction to single-use? 


In Europe we have seen some large chains embracing the switch to this new wave of packaging with enthusiasm, such as Ekoplaza supermarket in the Netherlands, Aloha Poké restaurant in Spain, and Le Pain Quotidien, across its whole footprint. 

We are still no closer to sorting out what happens to packaging when we don't need it anymore.

However, it was only when I started to better understand our recycling and waste management infrastructure that I realised the enormous challenges that come with these “solutions”. While these new companies may address the materials issue (moving away from using virgin oil to formulate the plastics and replacing it with lower-emission alternatives such as sugarcane or flax), we are still no closer to sorting out what happens to packaging when we don't need it anymore.

Diagram of different types of plastic
Different types of plastic; what they’re made from and how they can be recycled or broken down (Claire Rampen).

But surely it will just... break down? 

Before we get too excited about making everything compostable, we should ask ourselves what the knock-on infrastructure demands will be. For example, here are a few sobering facts about the composting infrastructure in my home country, the UK:

1/ Council provision of compost facilities (via home food waste collection) is not standard across the UK.

This WRAP 2019 report showed only 51% of English households had access to compost facilities. Participation in using the facilities is, of course, lower. 

In short, too few people have access to, or actually use, composting facilities.

2/ Home composting is also not powerful enough to handle most “compostable” plastics.

Yes, these materials will break down in the right conditions. No, they will not break down if you plant them in your garden or put them in your food waste bin and hope for the best. 

Companies like Vegware are investing in industrial composting sites to deal with the end-of-life of their products — but there just aren’t enough of them to cover the whole of the UK yet.

3/ We lack the facilities on our streets

People are most likely to be using single-use items when they’re out and about — but when was the last time you saw a compost bin on the street?

4/ Plant-based plastics are causing havoc in the current system

This is where it gets even more complex: a polymer made of oil is not the same as a polymer made of plants, and our current recycling infrastructure is only set up to identify and recycle oil-based plastics. Mixing polymers can contaminate the recycling, turning good intentions bad.

If you put compostable packing in the bin it may never break down, but if it does, similar to food waste decomposing in the wrong environment, it will emit methane — 84 times more potent than carbon dioxide


Are we being responsible? 

We’ve all done the bin dance, spending many a minute dithering over where to put our rubbish. At a conference recently I returned to the lunch area to find the packaging (labelled “compostable”) had been thrown into every bin there was. 

Life is increasingly getting more complex, both for consumers and for the waste-management companies sorting those bins.

As evidenced by the influx of these new plastics, the packaging industry can be quick to move, but building infrastructure to support it takes time.

Is it responsible to flood the market with “compostables” when we can’t handle their disposal? 

We need to take action; what can we do now?

Arguably, creating well-incentivised ‘circular’ systems (e.g. re-use) makes more sense than jumping on the new plastics bandwagon in the short-term. If you think this sounds like an idealistic solution, bear in mind that countries such as Norway and the Netherlands have demonstrated that this behaviour can work; they achieve return rates of packaging as high as 95% through their incentivised recycling schemes. 

Photo of A CupClub drop-off point in London
A CupClub drop-off point in London

There are plenty of these re-use companies springing up: for example, CupClub and Muuse tackle the on-the-go food and drink challenges by embedding tracking chips in their cups and plates and building a network of returns points. 

Crucially, these systems embed the mindset and behaviours we need to address this challenge. Re-use should always come before recycling — the fewer single-use items we need to manufacture (compostable or otherwise) the better. 

When 25% of people in a group adopt a new social norm, it creates a tipping point where the entire group follows suit.

The good news? You can be part of that solution — new research by the University of Pennsylvania found that “when 25% of people in a group adopt a new social norm, it creates a tipping point where the entire group follows suit”. So quite quickly re-use behaviours start to become the new normal. 

Refusing that coffee cup might not feel like a huge win for the climate on its own, but it models the change we want to see and gets us closer to that inflection point.