Whether we are hard-nosed users of our reusables or someone that barely gets take-out coffee, at some point or another, either through a rushed exit from home in the morning or a sudden need for caffeine after a particularly long commute – we may be handed a coffee cup (or indeed a pastry bag or salad box) that proudly bears the label ‘compostable’.
‘Hurrah’ we think. ‘I might have a single-use item in my hands but at least it is compostable. Phew. That’s great!’ Or is it. As simple as the ‘compostable’ label may appear, the issue itself is far more complex…
Firstly we need to understand the material itself. What exactly is compostable packaging? Well, it can be made from a variety of sources, but ultimately it is made from some kind of bio-based starting point, like PLA (or polylactic acid) which is made from cornstarch, or it may be made from bagasse, palm leaves, mushroom (mycelium) or even bamboo. All of these materials, being part of our ‘biological loop’ in a circular economy can be ‘returned’ to the earth through a form of degredation. Sometimes, these items look like the natural material they are made from, but sometimes they do not – PLA can look, for all intents and purposes, like plastic for example.

This, of course, is both a blessing and a curse. The bio-based alternatives to plastic are great to do the jobs that plastic was created for – lightweight and transparent, so you can see the items inside the packaging. They are also great at waterproofing card, so the liners to compostable cups are also often made from PLA.
So, I hear you cry – what’s the problem? The problem, like many things holding up a circular economy, is a lack of systems. Many types of compostable packaging cannot be just flung into a home compost heap – the temperatures and environment in the corner of your garden are just not up to breaking it down. Many people have demonstrated this by burying bags, cups and packaging labelled ‘compostable’ and then digging them up months later, completely intact. For compostables to work, they need to have much higher temperatures to break down – they need an industrial system to handle them. Compostable packaging could be a viable alternative to fossil-fuel based plastics, and in theory, provide that much needed nourishment back to the earth… but we have to think – when was the last time we put our empty compostable coffee cup into an industrial composting pickup bin? We probably haven’t – and why? Because they don’t really exist…
In the UK, compostable / biodegradable packaging pickups are sporadic and very patchy around the country. So whilst a compostable cup may feel better, in essence, it’s probably going straight to landfill or incineration when you place it in a bin – exactly the same as any other cup. What makes this issue even more complex, is that now, single-use plastic that is fossil fuel based is often picked up for recycling. But if a compostable one gets into the mix, that could contaminate the lot.
Eeeeesh right? The ‘bad’ option of regular plastic could actually be the ‘better’ option in this single-use example.
‘Ok – but compostable packaging falls to bits if it gets in the ocean right?’ Unfortunately, no. Whilst on the face of it, this ‘compostable’ or ‘biodegradable’ label feels like it is pretty harmless, because of the high temperatures and pretty specific environment that is needed to truly break down the material, if it gets into the ocean, it pretty much stays the same. The water is too cool, the microbes are not there and the cup floats away and breaks up into smaller pieces exactly the same as a ‘regular’ plastic cup.

So what to do? Well, if we head back to the home page and look at the hierarchy of actions, we really want to be looking at both Refuse and Reuse. If you can refuse the single-use option, do. Then of course, trying to prioritise our reusables – as you leave the house think keys, phone, wallet, cup, mask – or whatever mantra that suits you. If you get given a compostable cup, ask the retailer if they take it back for composting – some commercial pick-ups are spreading, so it is not all bad news. If not, ask if they can investigate whether a system is available to them. Lobby your local council or governing body to bring in kerbside compost pickups.
The systems will get better – until then, we just have to pay a little attention to the details…