It’s made from plants, but it’s still designed to be thrown away. Here’s what it really means when your chip packet says it’s compostable.

Compostable packaging seems so straightforward. It’s made from plants. It looks like plastic. And when it’s been used – probably to move some of your food around – it dissolves back into the earth to become soil again, then plants, then planty plastic. It could be truly circular, so what’s preventing these materials from replacing other kinds of packaging?

“The last six or seven years has seen a massive boom of compostable packaging, which are great solutions from the perspective of customer experience and safety,” says Kim Renshaw, founder of Beyond the Bin and member of Waste MINZ, an industry group for waste and resource recover organisations, including composters. She’s been paying keen attention to the number of things you might see in the supermarket tagged “compostable”. “The problem is that they are only compostable in a specific environment,” she says. 

You might already have heard that there’s a difference between home composts (the heap at the back of your garden) and commercial composting (an industrial process which uses more heat and creates a faster environment for decomposition, producing the kind of compost you might buy in bags at the garden centre or add to soil in parks to grow happier plants). The issue is that each commercial composting facility is a little different, using different heats and different lengths of time: a bliss ball packet that could compost in four weeks in one facility might take twelve weeks in another. 

“There’s no mandatory standard: there’s no regulation, there’s no legislation,” Renshaw says. When compostable products were first emerging “the composters said we’ll give it a go, we’ll take it”, but many found that the plant-derived polymers didn’t always work with their own processes. This is why, for example, Auckland’s food scraps collection bins don’t allow compostable packaging – and one of the reasons the food scraps collection exists is because not everyone can or does have a home compost. Currently, 10 composters around the country accept compostable packaging, according to the Waste MiNZ site. 

This leaves compostable packaging in something of a bind. Technically, it can degrade without producing plastic. But if it doesn’t end up in a compost bin, it ends up in the landfill, so is it any better than single-use plastic? 

“[Compostable] packaging is not more evil than any other piece of packaging,” says Owen Embling, the managing director of Hamilton-based packaging company Convex. As well as standard plastic packaging, Convex produces Econic packaging, which is used in Proper Crisps and Trade Aid chocolate, as well as coffee packs and bin liners. Econic is certified to European and American compostable standards, as New Zealand doesn’t have its own industrial regulations.

Embling points out that the period of time where compostable packaging might be exposed to air in a landfill, perhaps 12 weeks, is often enough for it to disintegrate. But if the organic matter the packaging is made out of is buried in landfills, it can generate methane, which standard plastic doesn’t do. “It’s not the Holy Grail or the only solution for eliminating plastics from the environment, but using renewable and plant-based products can help,” Embling says.

“There are no silver bullets,” agrees Fraser Hanson, the general manager of Decent Packaging, which produces compostable takeaway containers, coffee cups, and cutlery. “If a product is contaminated with food, we know it can’t be recycled – so we wanted to produce something that could be composted, made of the best materials.” 

When Decent Packaging started 11 years ago, most takeaway coffee cups were made from paper, lined with oil-based plastic film, and topped with a lid, often made from a different kind of plastic. “It could only go to landfill,” Hanson says; that mix of materials couldn’t be re-processed. After initially focusing on reusable containers, he realised that “banning single use will never work”, so he decided composting could be an alternative. “We know that a lot of our products don’t get composted in the end, but if we didn’t make it, would it just be oil-based plastic?” 

Part of the issue for commercial composters accepting compostable packaging is that products are not always developed in consultation with composters. “If you’re a composter, your business isn’t to process waste – it’s to build soil,” Renshaw says. “[Packaging] doesn’t add nutritional value to your soil.” In other words, it might help reduce single-use plastic, but it doesn’t necessarily help composters make a better product. 

Econic’s compostable packaging is mostly made from corn-derived starch, imported from the US and Europe, as well as wood fibre from New Zealand and elsewhere. Embling shows me an empty exemplar plastic: bendy and opaque, exactly like normal plastic to the untrained eye. The chemical process to turn these materials into polymers, or chains of molecules that can be flexible and waterproof just like oil-derived polymers in standard plastics, is complex. Making the packaging look good and function well requires inks and adhesives; in Econic’s case, these are often not plant derived, meaning that up to 40% of a piece of plastic can still be made from non-renewable (although still compostable, according to standards) materials.

Renshaw says that even the small amount of “wiggle room” allowed by the internationally accredited standards can still allow chemicals into compost, which is a problem if that compost will be used for growing food. “We know that some of those additives are harmful, even though we didn’t ten years ago,” she says. Some compostable plastics (although not Decent Packaging or Econic) contain PFAS or “forever chemicals”, which can linger in soil for generations and are linked to health problems. Water-based dispersion polymers, often used as a waterproof layer in cups, also have polymers in them, albeit ones with short enough molecular chains that they aren’t picked up by the international standards New Zealand compostable packaging producers use. 

Renshaw has shifted her focus to reusable packaging. “I hope that in 20 years, we’ll see this time of thinking that we have to have takeaways in single-use packaging as just a phase, and we’ll go back to sitting down to have a coffee in a cup,” she says. “With what I know about [single-use products], I’d much rather just get my drink in a sterilised ceramic cup.”

The ill-defined terms used on packaging, like “home compostable” versus “biodegradable”, don’t help. These words are often emblazoned across packets to help a company’s green credentials, but don’t necessarily give consumers more clarity about where the product should go when they’re done with it. Because biodegradable plastic looks so much like normal plastic (that’s the point after all), they can end up being placed in the wrong waste stream. 

That said, everyone I spoke to for this article agreed that concerns about compostable plastics contamination was overblown – all waste systems are designed to deal with some pieces of unfamiliar packaging. “It contaminates waste no more than bits of stick,” Embling says. “Everything that’s compostable that we make has a big note on it.” Renshaw empathises with confused consumers. “It’s rough, hey?” she says. “No one wants to do the wrong thing – it’s just that it’s often too complicated for the average person to learn what everything means.”

There are ways to prevent contamination. Decent Packaging’s coffee partners, including Eight Thirty and Kokako, have specific bins for compostable packaging, which guarantees that they will be picked up by someone who accepts it. The company also supplies the entirety of Spark Arena, where visitors aren’t allowed to bring their own food and drink: this means that there is just one bin, and everything that goes into it can be composted. “There’s no excuse to put it in the wrong bin, and there’s no need to separate it,” Hanson says. “The dream is to have easy access to compostable infrastructure, with a true end of life.” He’d like to get to the point where takeaway packaging is compostable by default, without needing to win any sustainability points by doing so, even if that meant his company lost one marker of differentiation. 

Embling is especially frustrated with supermarkets and big box stores that collect soft plastics, while making it difficult for food producers to use different kinds of packaging. “They say they don’t want contamination in their soft plastic bins,” he says. “But it’s basically zero risk – then they turn those soft plastics into fence posts or bollards, basically just distributing a landfill full of rubbishy plastic bags around the country.”

While the compostable packaging space has a lot of conflicting views and vested interests, everyone seems to agree that this makes the need for clarity and leadership even more stark. So far, all they have is a “position statement” from the Ministry for the Environment, not a law, regulation, or single industry body. (The Spinoff asked Penny Simmonds, the minister for the environment, about whether the government would be revising the compostable packaging guidelines, but her office was unable to provide a response in time.) The position statement supports the use of international standards and use of composting for diverting food waste to compost, not landfill (for example as bin liners), and to stop plastic polymers from entering the soil.

So has compostable packaging really made a difference? In a statement, Auckland Council said that it has seen a reduction in waste volumes over the last few years, from more than a tonne per person going to landfill each year to 873 kilos. But this is mostly due to food scraps collection, especially since they don’t interact with packaging disintegrating in home composts. It’s found a very low rate of compostable packaging in food scraps bins, so the product isn’t contaminating that waste stream. 

As producers of compostable products, both Embling and Hanson would like to see better infrastructure and awareness for dealing with their packaging once it’s left their premises. Of course they would – it would help their businesses. But for now, it’s difficult to imagine home rubbish bins filled to the brim with compostable muesli bar wrappers and takeaway cups and napkins and shampoo bottles and tooth brushes, let alone backyard compost heaps hot and healthy enough to absorb the volume of packaging households produce in plastic. 

For all the angst about what to do with compostable products, they’re only a drop in the (microplastic filled) ocean, given the volume of waste New Zealand produces. I ask Embling what percentage of his plastics business Econic is. “About 5%,” he says, frowning, the painting of a forest on the wall behind him a world away from a crumpled piece of wrapping in the bin. “But I’d love it to be more.”