Breaking Down Bioplastics

Is the Bioplastic Cup Half Full or Half Empty?

You’re standing in front of three bins – one for compost, one for recycling and one for landfill – holding an empty container called a “PlantBottle” and a clear plastic cup embossed with the recycling triangle and the number seven. Now what? Your instinct might be to put that “PlantBottle” in the compost bin, and to put the clear plastic cup in the recycling bin. But in this case, you’d be wrong on both counts.

PlantBottle is Coca-Cola’s brand for its bio-based plastic bottles, and while they are made either partially or wholly from plant-derived materials, they have the identical chemical structure of plastic made from oil, and therefore should be recycled right along with petro-derived plastic. A PlantBottle, despite its name, can’t be composted.

And the cup bearing the recycling logo and the number seven? Seven is the catchall for plastics that aren’t generally recyclable but that a few curbside systems might take – things like durable goods such as sunglasses, DVDs and some types of rugged plastic packaging. Compostable plastic is lumped under number seven, too. This cup in your hand happens to be a compostable bioplastic material, PLA, and so, though it might seem counterintuitive, it is supposed to go in the compost bin. Of course, if the word “compostable” were printed on the cup, this would be obvious. But such hints are not always provided.

If this all seems confusing, that’s because it is. But we’re here to shine a light on bioplastic packaging and its end-of-life story, because you’ll be seeing more and more of it in the coming years. Any sustainable business worth its weight in wheatgrass is starting to use bioplastic packaging. And within the packaging industry, this stuff is the new black. The market for bioplastics is forecast to grow at an average annual rate of about 25 percent through 2015, with production reaching 884,000 tons by 2020.

Set against the haunting images of our plastic-choked oceans and landscapes, and considering the pathetically low recycling rates in the US (only about 30 percent of polyethylene terephthalate, or PET, bottles are collected for recycling), the rise of bioplastics seems, at first glance, encouraging. With municipalities across the country banning standard, petroleum-based, single-use plastics and some mandating residential composting, more businesses and consumers are looking for plastic packaging that will, poof!, disappear once its short, useful life is over.

But – spoiler alert – that’s not actually how it all works. For one thing, bioplastics vary widely in terms of both their base material and their ability (or inability) to biodegrade. For another, bioplastics are causing problems for both plastics recyclers and for commercial composting facilities because they are often wrongly sorted.

So while bioplastics have the potential to significantly reduce our dependence on fossil fuels to create packaging, they’re no panacea. And they don’t always work as advertized. In fact, they often overpromise and underdeliver, says Jack Macy, commercial zero waste coordinator for San Francisco’s Department of the Environment. When it comes to claims around bioplastics being biodegradable and compostable, “there’s about as much greenwashing and distortion of reality as anything I’ve seen,” he says.

First, let’s start with a primer on the term “bioplastic.” Basically, a bioplastic is a polymer made – wholly or in part – from a renewable, plant-based feedstock. There are some exceptions to this rule, such as Ecoflex, a bioplastic made from petrochemicals. It earns its “bioplastic” label from the fact that it will biodegrade when placed in a commercial composting system. As you can see, the term bioplastic is quite broad.

Some bioplastics are designed such that microorganisms inside a compost pile will completely consume them within a relatively short period of time. Other bioplastics will decompose under certain conditions, but they will not do so quickly or completely enough to be considered compostable. Some producers claim their packaging is biodegradable, when in reality it just contains additives that make the plastic break down into small pellets.

So it’s very important to note that “bio-based,” “biodegradable” and “compostable” are individual attributes. A given bioplastic might be all three of these things – for example a bioplastic called polylactic acid (PLA) made from corn by the Cargill-owned NatureWorks company; or it might only be one of these things – such as the PET or high-density polyethylene (HDPE) PlantBottle that is bio-based (and recyclable) but not biodegradable or compostable.

Come Again?
Given this morass of feedstocks and end-of-life options, it’s impossible to chart the lifecycle of bioplastics as a group; it must be done per material. That isn’t easy given there are around 13 different bioplastics in use today.

“Confusion is rampant right now,” says Dabny Hoover, senior resource specialist for the Natural Resources Defense Council. “A lot of people are focused on biodegradability, but that’s misleading and doesn’t mean it’s always better for the environment.” In some cases, a material that is bio-based but designed for recycling might be the better option. The mere fact that something is bio-based doesn’t make it a clear winner environmentally. “You need to consider the fertilizer, pesticides (used to grow the crops). You have to consider the entire lifecycle,” says Susan Selke, professor and associate director of the School of Packaging (yes, there is such a thing) at Michigan State University.

A study done at the Mascaro Center for Sustainable Innovation at the University of Pittsburgh found that merely using bio-based feedstocks instead of petroleum feedstocks does not necessarily reduce the material’s early-life environmental impact. In some cases it can actually deepen it. As when feedstocks are derived from corn – which they often are – raised using conventional industrial farming techniques (read: heavy reliance on petro-chemical fertilizers). The report didn’t consider the various end-of-life options for bioplastics as they’ve not been widely documented and vary widely.

Everything in Its Not-So-Right Place
Which brings us back to the confusion at the recycling bin. For argument’s sake, let’s say you put the PET PlantBottle in the compost bin (a reasonable mistake) and put the mystery cup in the recycle bin (after all, it looks and feels like normal plastic). Then what?

Today, the hundreds or thousands of compostable empties that pile up at a music festival likely end up in a landfill. Unless it gets hand-sorted, that PLA cup is likely going to end up in the PET stream in a recycling facility, where it doesn’t belong. And that PET PlantBottle will go to a composting facility, where it’ll be rooted out and sent to the landfill instead of being recycled.

Back at the recycling facility, PLA can be mechanically separated from PET using an infrared sensor. But recyclers don’t usually take the trouble to do such sorting. It’s an expensive process and no one is going to pay them enough for that PLA to justify the cost, explains David Cornell, technical director of the Association of Postconsumer Plastic Recyclers. (That could change soon, but we’ll get to that later.)

Within the PET stream, PLA tends to muck things up. If enough PLA (or other non-PET material) ends up in a bale of PET, a plastics reclaimer is going to turn it away and the bale will likely end up in a landfill. So suddenly those earth-friendly packaging materials have cut short the possibility that the PET inside that bale will find another useful life before ending up in a landfill. (Most PET is downcycled into other products, such as clothing or construction material, rather than truly recycled, due to the complexity and cost of turning PET back into PET.)

But even if the PLA and PET are put in their proper bins, one can argue that the recyclable PET’s end of life scenario is better than compostable PLA’s. For one thing, the composting facility is likely to pull that PLA cup out of the compost material and trash it. “Anything that looks like plastic is a problem to composters,” Cornell says, because they can’t easily discern whether a material is a compostable bioplastic when it’s moving quickly past on a conveyer belt.

For composters who cater to organic farmers, bioplastic can be an even bigger problem. Because bioplastics go through a process of polymerization, they are considered a synthetic material and therefore don’t meet the USDA’s National Organic Program’s standards. “We might consider toxicity of a material, too, but the first thing we consider is whether it is synthetic,” says Lindsay Fernandez-Salvador, a program manager at the Organic Materials Review Institute (OMRI), which determines whether specific agriculture input products, such as compost, meet the organic standards. “And if it is, we disallow it.”

Needless to say, this creates a bit of a quandary for composters who want to maintain their OMRI listing but who also want to accept bioplastic packaging in their intake materials. They simply can’t do both. “The compostable plastic industry started making this material without input from the composting industry,” says Will Bakc, co-owner of Sonoma Compost in Petaluma, CA. “They never thought through the life cycle.”

As a result of this disconnect, you might be dutifully placing compostable plastic into a municipal compost collection bin (assuming you live in one of the few US cities that currently provides this type of curbside collection) only to have the commercial composter pull it out of the stream and divert it to the landfill.

That’s a nasty carbon footprint for those eco-containers.

A Brighter Future
Because it is made from agricultural byproducts and its recycling infrastructure is already established, bio-based PET and HDPE, such as the PlantBottle packaging that Coca-Cola uses, is a step in the right direction. (But while 100 percent of an HDPE PlantBottle is bio-based, only 30 percent of a PET PlantBottle is bio-based, though Coca-Cola says it is working to boost that percentage. And PepsiCo recently announced it is transitioning to 100 percent bio-based feedstock for its PET bottle.)

Compostable materials like PLA are obviously a step in the right direction as well. And while these materials don’t add any nutrient value to compost, many experts agree that they do add some value to the compost stream by making it easier for consumers or restaurants to divert food waste from a landfill. If, say, your week-old take-out leftovers are in a compostable bioplastic container, you might be more likely to toss the whole box in the compost bin than you would be to open it up and dump the food out.

But much of the PLA used today is in the form of single-use beverage cups, which don’t play a role in diverting food waste from landfills. In fact, the PLA beer cup is becoming a ubiquitous sight in beer gardens and venues that want to “do the right thing.” Today, the hundreds or thousands of empties that pile up at the end of a festival or sports event are likely landfilled. Or, perhaps, erroneously sent to recyclers, who then landfill them, or send them to composting facilities, which may or may not accept them.

Mike Centers, an entrepreneur based in Northern California, is trying to create a third option: PLA recycling. Currently, there are two PLA recyclers in the world – one in Wisconsin and another in Europe. But there’s no collection infrastructure, so Centers is trying to build one.

The business model for his startup, BioCor, is to purchase PLA scrap from packagers and recyclers or directly from facilities, such as entertainment or sports venues, and sell it to the Wisconsin facility, which breaks it down into its component lactic acid and sells it back to NatureWorks … which then turns it back into PLA.

This would allow recyclers who are currently losing money due to bales of PET contaminated with PLA to turn that deficit into a revenue stream by removing the PLA and selling it to BioCor. NatureWorks would rely less on field corn as a feedstock and greatly increase the recycled content of PLA. And eventually, more PLA recycling facilities would be built around the country, thereby reducing transportation costs and closing the loop more tightly.

Plus, recycling PLA allows the embedded energy inside each cup – which is lost when the material is composted – to be reused. “We don’t think composting PLA makes a lot of sense – except for applications in the food service industry where it might facilitate more food diversion from the landfills, ” says Steve Davies, marketing and PR director for NatureWorks. “But if you have a bag full of plastic PLA cups, why would you compost that? We’d rather preserve the value of the PLA molecule (and reuse it).”

Centers is keen to gather up as many of those PLA molecules as possible. “Our goal is to collect 400,000 pounds per month,” he says. He’s certainly got his work cut out for him. In its first year of operation, BioCor has only scared up about 180,000 pounds of the stuff.

Today, nearly half of all bioplastic packaging in the world is PLA, according to research firm Pira International. If it continues to dominate the field, BioCor has a real shot at developing a nationwide PLA collection infrastructure. That would help make PLA a truly renewable resource, and it might just make it a little easier to put bioplastic packaging in its right place.

Just don’t forget to keep the PlantBottles out of the compost bin.

The Bioplastics Quiz

  • All bioplastics are made from plants. True or False?
  • All recyclable plastics are made from petroleum. True or False?
  • The type of plant that can be turned into plastic is …
  • All bioplastics can be composted. True or False?
  • Which is a better end-of-life scenario for bioplastics: recycling or composting?

Answers to the Quiz

  • False. Some bioplastics are derived only from plants. Polylactic acid (PLA) is one. But some bioplastics contain – wait for it – petroleum. Bioplastics made from oil, however, can biodegrade in certain environments.
  • False again. Scientists have known how to create many of our commonly used plastics, including high density polyethylene (HDPE) and polyethylene terephthalate (PET), from plant-derived materials for many years. But packagers are only now figuring out how to scale up production of these materials such that they can start transitioning their massive operations to renewable resources. Coca-Cola and PepsiCo are already using, or will soon use, bio-based, fully recyclable HDPE and PET.
  • Trick question. First off, there are many different plants that can be turned into plastic. Today, NatureWorks, which produces Ingeo, the most widely used brand of PLA, uses dextrose derived from field corn as its feedstock. (Cargill owns NatureWorks, so they have a rather secure supply of corn.) Sometimes sugarcane is used as feedstock. But bioplastic manufacturers are no dummies. They know using feedstocks derived from agricultural waste is a better option and say they are actively seeking to transition to alternate feedstocks, including those that can be derived from the cellulosic materials within agricultural waste.
  • Totally false. Many bioplastics are not compostable. Even some that are biodegradable are not compostable according to standards set by the American Society for Testing and
  • Another trick question. First, don’t forget that some bioplastics, such as PET and HDPE, can’t be composted, nor do they biodegrade. And so, of course, recycling (after re-using as many times as possible, of course) is the best end-of-life option for those. And recycling is also the better option for biodegradable or compostable bioplastics, as well, because it’s a way to retain and extend the usefulness of the material. But there’s a catch: Outside of bio-based HDPE and PET, there’s no infrastructure for capturing recyclable bioplastics – yet.


Earth Island, 2011-06-03.


Association of Postconsumer Plastic Recyclers
Coca-Cola Co.
Mascaro Center for Sustainable Innovation
Michigan State University
Natural Resources Defense Council (NRDC)
NatureWorks LLC
Organic Materials Review Institute (OMRI)
PIRA International
US Department of Agriculture (USDA)


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