If you buy a smoothie in Portland, Oregon, the drink might come in a compostable plastic cup, a choice a thoughtful owner might make to make their operations more sustainable. You might think, at a quick glance, that you’re helping avoid part of the global waste problem. But Portland’s composting program, as in many cities, specifically bans compostable packaging from its green bins—and this type of plastic won’t break down in a backyard composter. Though it’s technically compostable, the container will end up in a landfill (or perhaps the ocean), where the plastic may last as long as its fossil fuel counterpart.
It’s one example of a system that offers incredible promise for reshaping our waste problem but is also deeply flawed. Only around 185 cities pick up food waste at the curb for composting, and fewer than half of those also accept compostable packaging. Some of that packaging can only be composted by an industrial composting facility; some industrial composters say that they don’t want it, for a variety of reasons that include the challenge of trying to sort out regular plastic, and the fact it can take longer for the compostable plastic to break down than their normal process. One type of compostable packaging contains a chemical that is linked to cancer.
As companies struggle to deal with the challenge of single-use packaging, compostable options are becoming more common, and consumers might consider it greenwashing if they knew that the packaging won’t ever actually be composted. The system, though, is beginning to change, including new innovations in materials. “These are solvable problems, not inherent problems,” says Rhodes Yepsen, executive director of the nonprofit Biodegradable Products Institute. If the system can be fixed—just like the broken recycling system needs to be fixed—it can be one piece of solving the bigger problem of growing trash. It’s not the only solution. Yepsen says that it makes sense to start by reducing packaging and prioritizing reusable products, and then design whatever’s left to be recyclable or compostable depending on the application. But compostable packaging makes particular sense for food; if both food and food packaging can be composted together, it could also help keep more food out of landfills, where it’s a major source of methane, a potent greenhouse gas.
The science of composting
Composting speeds up the natural process of decay of organic matter—like a half-eaten apple—through systems that create the right conditions for waste-eating microorganisms. In some cases, that’s as simple as a pile of food and yard waste that someone manually turns over in a backyard. The mix of heat, nutrients, and oxygen has to be right for the process to work well; compost bins and barrels make everything hotter, which speeds up the transformation of waste into rich, dark compost that can be used in a garden as fertilizer. Some units are even designed to work inside a kitchen.
In a home composter or backyard pile, fruit and vegetables can break down easily. But a backyard bin likely won’t get hot enough to break down compostable plastic, like a bioplastic takeout box or fork made from PLA (polylactic acid), a material produced from corn, sugarcane, or other plants. It needs the right combination of heat, temperature, and time—something that’s likely to happen only in an industrial composting facility, and even then only in some cases. Frederik Wurm, a chemist at the Max Planck Institute for Polymer Research, has called PLA straws “a perfect example of greenwashing,” since if they end up in the ocean, they won’t biodegrade.
Most municipal composting centers were originally designed to take yard waste like leaves and branches, not food. Even now, of the 4,700 facilities that take green waste, only 3% take food. San Francisco was one city that was early to adopt the idea, piloting food waste collection in 1996 and launching that citywide in 2002. (Seattle followed in 2004, and eventually many other cities did too; Boston is one of the latest, with a pilot beginning this year.) In 2009, San Francisco became the first city in the U.S. to make recycling food scraps mandatory, sending truckloads of food waste to a sprawling facility in California’s Central Valley, where it’s ground up and placed in huge, aerated piles. As microorganisms chew through the food, the piles heat up to as hot as 170 degrees. After a month, the material is spread out in another area, where it’s turned by a machine daily. After a total of 90 to 130 days, it’s ready to be screened and sold to farmers as compost. Recology, the company that runs the facility, says that the demand for the product is strong, particularly as California embraces spreading compost on farms as a way to help soil suck up carbon from the air to fight climate change.
For food waste, it works well. But compostable packaging can be more challenging even for a facility of that size. Some products can take as many as six months to break down, and a Recology spokesperson says that some of the material has to be screened out at the end and run through the process a second time. Many other compostable containers are screened out in the beginning, because they look like regular plastic, and are sent to landfills. Some other composting facilities that work more quickly, aiming to produce as much compost to sell as possible, aren’t willing to wait months for a fork to decompose and don’t accept them at all.
A package that dissolves in your backyard—or the ocean
Most chip bags end up in landfills, since they’re made of multiple layers of materials that can’t be easily recycled. A new snack bag in development now from PepsiCo and the packaging company Danimer Scientific is different: Made from a new material called PHA (polyhydroxyalkanoate) that Danimer will begin producing commercially later this year, the bag is designed to break down so easily that it can be composted in a backyard composter, and will even break down in cold ocean water, leaving no plastic behind.
It’s at an early stage, but it’s an important step for several reasons. Since the PLA containers that are typical now can’t be composted at home, and industrial composting facilities are reluctant to work with the material, PHA provides an alternative. If it ends up in an industrial composting facility, it will break down faster, helping solve one of the challenges for those businesses. “When you take [PLA] into an actual composter, they want to turn that material over much more quickly,” says Stephen Croskrey, Danimer’s CEO. “Because the faster they can turn it over, the more money they make. The material will break down in their compost. They just don’t like that it takes longer than they want it to take.”
PHA, which can also be turned into various plastic products, is made differently. “We take vegetable oil and feed it to bacteria,” says Croskrey. The bacteria make the plastic directly, and the composition means that bacteria also break it down more easily than regular plant-based plastic. “Why it works so well in biodegradation is because it’s a preferred food source for bacteria. So as soon as you expose it to bacteria, they’ll start gobbling it up, and it will go away.” (On a supermarket shelf or delivery truck, where few bacteria are present, the packaging will be completely stable.) Tests confirmed that it even breaks down in cold ocean water.
Giving the opportunity for the package to be composted at home can help fill a gap for people who don’t have access to composting at the curb. “The more we can remove barriers from consumers to be involved in a form of composting or recycling, the better,” says Simon Lowden, president and chief marketing officer of global foods at PepsiCo, who leads the company’s sustainable plastics agenda. The company is working on multiple solutions for different products and markets, including a fully recyclable chip bag that will soon come to market. But a biodegradable bag may make more sense in places where the capacity exists to break it down. The new bag will come to market in 2021. (Nestlé also plans to use the material to make plastic water bottles, though some experts argue that compostable packaging should be used only for products that can’t be easily recycled or reused.) PepsiCo aims to make all of its packaging recyclable, compostable, or biodegradable by 2025 to help with its climate goals.
If the material isn’t composted and is accidentally littered, it will still disappear. “If a fossil fuel-based product or an industrial compostable product finds its way into a creek or something and ends up in the ocean, it’s just bobbing around out there forever,” says Croskrey. “Our product, if it does get thrown away as litter, will go away.” Because it’s made from vegetable oil rather than fossil fuels, it also has a lower carbon footprint. Pepsi estimates that the packaging will have a 40-50% lower carbon footprint than its current flexible packaging.
Other innovations in materials could also help. Loliware, which makes straws from a seaweed-based material, designed the straws to be “hyper-compostable” (and even edible). Scotland-based CuanTec makes a plastic wrap from shellfish shells—which one U.K. supermarket plans to use to wrap fish—that can be composted in a backyard. Cambridge Crops makes an edible, tasteless, sustainable (and compostable) protective layer for food that can help eliminate the need for plastic wrap.
What does a green stripe tell you?
Earlier this year, one large composting facility in Oregon announced that, after a decade of accepting compostable packaging, it no longer would. The biggest challenge, they say, is that it’s too difficult to identify if a package is actually compostable. “If you see a clear cup, you don’t know if it’s made out of PLA or conventional plastic,” says Jack Hoeck, vice president of the company, called Rexius. If the green waste is coming from a café or a home, consumers may have accidentally dropped a package in the wrong bin—or may not understand what’s okay to include, since the rules can be byzantine and vary widely between cities. Some consumers think “food waste” means anything related to food, including packaging, Hoeck says. The company decided to take a hard line and only accept food, even though it could easily compost materials like napkins. Even when composting facilities ban packaging, they still have to spend time sorting it out from rotting food. “We have people that we pay piece-rate and they have to hand-pick it all out,” says Pierce Louis, who works at Dirthugger, an organic composting facility. “It’s gnarly and disgusting and awful.”
Better communication could help. Washington State was the first to adopt a new law that says that compostable packaging has to be readily and easily identifiable through labels and markings like green stripes. “Historically, there were products that were getting certified and marketed as compostable but the product might be unprinted,” says Yepsen. “That’s going to be illegal in the State of Washington. . . . You have to communicate that compostability.”
Some manufacturers use different shapes to signal compostability. “We introduced the teardrop cutout shape in the handles of our utensils, which makes it easier for composting facilities to recognize our shape means compostable,” says Aseem Das, founder and CEO of World Centric, one compostable package company. He says that there are still challenges—a green stripe isn’t difficult to print on a cup, but it’s harder to print on lids or clamshell packages (some are embossed now, which is too difficult for composting facilities to identify). As the industry finds better ways to mark packages, cities and restaurants will also have to find better ways to let consumers know what can go in each bin locally.
Is this stuff even safe?
The molded fiber bowls used by restaurants like Sweetgreen are compostable—but right now, they also contain chemicals called PFAS (per- and polyfluoroalkyl substances), the same cancer-linked compounds used in some nonstick cookware. If a carton made with PFAS is composted, the PFAS will end up in the compost, and then could end up in food grown with that compost; the chemicals could also potentially transfer to food in a takeout container as you’re eating. The chemicals are added to the mix as the bowls are made in order to make them resistant to grease and moisture so that the fiber doesn’t get soggy. In 2017, the Biodegradable Products Institute, which tests and certifies packaging for compostability, announced that it would stop certifying packaging that intentionally added the chemical or had a concentration over a low level; any currently certified packaging would have to phase out PFAS use by this year. San Francisco has a ban on the use of food-service containers and utensils made with PFAS, which will take effect in 2020.
Some thin paper takeout boxes also use the coating. Last year, after one report found the chemicals in many packages, Whole Foods announced that it would find an alternative for the boxes at its salad bar. When I last visited, the salad bar was stocked with boxes from a brand called Fold-Pak. The manufacturer said that it uses a proprietary coating that avoids fluorinated chemicals, but it wouldn’t provide details. Some other compostable packages, such as boxes made from compostable plastic, aren’t manufactured with the chemicals. But for molded fiber, finding an alternative is challenging.
“The chemical and food-service industries have been unable to come up with a consistently reliable alternative which can be added to the slurry,” says Das. “The options are then to spray a coating or laminate the product with PLA as a post-process. We are working on finding coatings which can work to provide the grease resistance. PLA lamination is available but increases the cost by 70-80%.” It’s an area that will require more innovation.
Zume, a company that makes packaging from sugarcane, says that it can sell uncoated packaging if customers request it; when it coats packages, it uses another form of PFAS chemicals that are thought to be safer. It’s continuing to look for other solutions. “We view this as an opportunity to drive sustainable innovation in the packaging space and progress the industry,” says Keely Wachs, head of sustainability at Zume. “We know that compostable molded fiber is a critical part of creating a more sustainable food system, and so we are working with partners to develop alternative solutions to short-chain PFAS. We’re optimistic as there’s amazing innovation happening in materials science, biotechnology, and manufacturing.”
What will it take to grow compostability?
For materials that can’t be composted in a backyard—and for anyone without a yard or the time to compost themselves—city composting programs will also have to expand for compostable packaging to make sense. Right now, Chipotle serves burrito bowls in compostable packaging at all of its restaurants; only 20% of its restaurants actually have a composting program, limited by what city programs exist. One first step is finding a way for industrial composters to want to take the packaging—whether that’s addressing the problem of the time that it takes for packaging to break down or other issues, like the fact that organic farms currently only want to buy compost made from food. “You can start talking about, realistically, what would you have to change in your business model to be able to successfully compost compostable products?” says Yepsen.
Robust infrastructure will take more funding, and new regulations, he says. When cities pass bills that require phasing out single-use plastic—and allow for exceptions if packaging is compostable—they’ll have to make sure that they have a way to collect those packages and actually compost them. Chicago, for example, recently considered a bill to ban some products and require others to be recyclable or compostable. “They don’t have a robust composting program,” Yepsen says. “So we want to be in a position to approach Chicago at the ready when things like that come up and say, hey, we support your initiative to have compostable items, but here’s the sister companion bill that you really need to have a plan for composting infrastructure. Otherwise, it doesn’t make sense to require businesses to have compostable products.”