The Tea on Compostable Coffee Cups
Just a few years ago, it seemed like compostable alternatives to single-use items were the thing - the ‘way of the future’. A seemingly simple way to have systems remain as they are whilst diverting billions of resources that would otherwise end up in landfills, to compost instead.
The magic takeaway coffee solution. Right?
The answer to our waste and pollution crisis! Right?
Not so fast.
Takeaway coffee cups have become an exponentially growing phenomenon in recent decades. Lives have become more fast paced and humans are increasingly favouring convenience, but doing so at a cost to our environment. The apparent solution - creating these single-use resources out of plant-derived alternatives instead of fossil fuels - turns out to be more problematic than we had been lead to believe.
Are compostable coffee cups a marketing greenwash… or are they really a sustainable solution? Unfortunately, it’s not so simple.
Let’s start with some background.
Before compostable coffee cups - conventional disposable coffee cups were likely to be a paper, plastic or even polystyrene cup with a plastic lid. Paper cups were lined with polyethylene plastic to prevent hot coffee from leaking or the cup from going soggy. These cups had nowhere to go but landfill - the plastic content could not be recycled. In recent years, however, we have seen the uprise of the ‘compostable’ model - paper cups lined with plant-based bio-plastics. Derived from plant sugars, these are known as PLA (polylactic acid).
Whilst it seemed like a positive step - many complications started revealing themselves.
First off, there’s no use having a compostable item if it doesn’t get composted. Many of these compostable cups do not make it to a composting facility. The Packaging Forum estimates that 295 million beverage cups are used by New Zealanders alone every year, with the vast majority being landfilled - including compostable coffee cups. There is so much misinformation and confusion around where our disposable coffee cups should go - composting labels are not standardised and conflicting information can be difficult to comprehend. Along with this, most councils do not have public compost bins for coffee cups.
So most cups end up in landfills anyway, where studies have suggested that due to being deprived of oxygen in the landfill’s anaerobic environment, they produce methane, a potent greenhouse gas.
In today’s environment where serviceware labelled compostable is rife, you would be forgiven for not even questioning that disposable coffee cups made with a paperboard that state ‘compostable’, ‘eco’ or ‘made with plants’ can go in any compost. However, they need to be commercially composted. This is because these cups are not made of paper alone (which makes sense when you think about it - if you were to pour a hot coffee into paper, the cup would become soggy or leak). These cups are, as stated above, lined with a bioplastic called PLA. To break down, PLA must be composted at temperatures of 55 degrees or higher, generally only achieved in commercial composting settings. Many professional composters have had trouble composting PLA, finding that the temperatures have to be very high (e.g. even higher than the standard 50-65 hot compost range) for long periods of time, which is not only very difficult to achieve but not good for the microbial life in the compost. Given these problems, although these cups are marketed as compostable, they are not accepted in council kerbside food waste collections, or at many composting facilities. In fact, there are only 12 industrial and 3 community facilities in New Zealand that will accept any form of compostable packaging. Of these, even fewer will take items with a PLA content, like coffee cups, due to the risk of contamination from other plastics and the risk of compostable packaging devaluing the quality of compost. Compostable coffee cups do not add nutritional, fibre or economic value to compost (Sustainable Business Network 2019), and composters are overwhelmingly sceptical, not wanting to take it on to preserve the quality of their product.
Even if these ‘compostable’ coffee cups do make it to the end stage where they are broken down in an adequate facility, there is the risk that microplastics and chemicals may remain - specifically from fibre-based compostables, which often require PFA’s (polyfluoroalkyl substances) to make them more liquid and grease resistant. PFA’s can harm soil, and end up in our waterways and food chain. If that is not enough, ‘new kid on the packaging block’ called water-based dispersion coating (WBDC) claims to combat the need for any plastic lining. The ‘water-based’ coating acts as the barrier to leakages, but although marketed as 100% plastic-free… yes… does still contain small quantities of plastic polymers which would end up in the soil. (Takeaway Throwaways 2021)
So, a complex issue. Next time you get a takeaway coffee - beware of your green ‘eco’ throwaway cup. It will tell you it can be compostable, but chances are it won’t be composted. A better approach is the bring your own cup, or treat yourself and sit down to have your coffee in a have-here cup. You don’t need to worry about where those reusable cups go because they can just be reused, and reused, and reused.
Whilst compostable coffee cups may seem like a step in the right direction, the reality is that in the transition to more environmentally protective systems, our focus needs to remain on the waste hierarchy, where reduction and reuse are prioritised. Compostable coffee cups, even in a best-case scenario where they are composted and add no contaminants to the soil, are still single-use products whose mass manufacturing and disposal processes are energy-intensive and a contributor to greenhouse gas emissions and resource depletion.
Wherever you can, refuse the single-use, encourage reduction, and reuse.
Reviewed by
Hannah Blumhardt and Liam Prince of The Rubbish Trip
Sources
Ministry for the Environment 2022
Sustainable Business Network 2021
