Have you heard about Coca-Cola’s new and improved bioplastic bottle named PlantBottle? It’s 100% polyethylene terephthalate (PET)… But wait! Isn’t that just plastic type #1, made from fossil fuels?
Adding to the confusion over terms like “bioplastic,” “biodegradable,” and “bio-based plastic,” you may now feel the need to figure out if the PET plastic bottle containing your favorite beverage, food, or personal care product is made out of non-renewable fossil fuels and/or actual plant material. [Spoiler alert: It could be either, but neither is biodegradable.]
In this article, you’ll find out what all these terms mean—or at least how they are used in real life. So next time you’re shopping for eco-friendly products, you’ll know what to look for and what to avoid.
Table of Contents
- What Are Bioplastics?
- Is There a Legal Definition of Bioplastic?
- Is There a Legal Definition of Biodegradability?
- History of Bioplastics
- What Are the Major Types of Bioplastics?
- What Are Bioplastics Used in?
- Case Study: Coca-Cola’s PlantBottle
- Why Haven’t Bioplastics Replaced Fossil Fuel Plastic?
- Are Bioplastics More Sustainable (and/or Less Toxic) Than Fossil Fuel Plastics?
- Can Bioplastics Be Recycled?
- How Can You Reduce Plastic Pollution?
- Final Thoughts on Bioplastics
What Are Bioplastics?
In looking at the root words in bioplastic, it’s fair to say that bioplastic is a specific type of plastic containing something of biological origin. Traditionally, plastics are defined as long chains of repeating carbon-containing units (monomers) derived from fossil fuels. They are often called synthetic polymers or resins.
Fossil-fuel-based plastics may break down over decades—sometimes centuries—into micro- or nanoplastic pollution known to be harmful to human health and the environment.
Is this true for bioplastics as well?
As we’ll see below, the answer is yes—this is true for most bioplastics, too.
As you can see, this can get very confusing very fast. With a lack of universally accepted definitions, companies have taken advantage of the semantic challenges and use these terms to mean very different things.
So without a solid universal definition, how are people actually using the term “bioplastic” in real life?
Based on what I’ve read, people use the term “bioplastic” in three distinct ways. So it’s fair to say that there are at least three different meanings of bioplastic.
- Bioplastic may mean that all or some of the materials used to make it are plant-derived. In this sense, bioplastics are bio-based. They are made (at least in part) from biological materials such as residues from sugarcane, corn, cassava, food waste, or wood. However, there are almost always fossil fuel-derived chemicals (petrochemicals) in bioplastics. The exception are those designated as 100% plant-based, but that’s very rare (at least at this time).
- Bioplastic may mean that it is biodegradable. This means that it will decompose completely by naturally occurring microbes (algae, bacteria, or fungi) into simple substances like carbon dioxide and water after disposal. However, opinions on the real definition of “biodegradable” vary as well, making things even murkier. For example, the time frame for how long a “biodegradable” material might take to break down varies widely. We’ll get to this more in a minute.
- Bioplastic may mean that something is both bio-based and biodegradable as these terms are described here.
These meanings are not synonymous. In fact:
- Some bioplastics are not even bio-based.
- Not all bioplastics will biodegrade.
- Most bioplastics that will biodegrade are not compostable under natural conditions. (For example, they may only be able to biodegrade in an industrial composting facility.)
Adding to the confusion are greenwashing terms for bioplastics like plastic-free, sustainable, or earth-friendly. None of these terms is really true (or at least they are only partly true).
Is There a Legal Definition of Bioplastic?
There is no legal definition of bioplastic, nor even one that is universally accepted. This means there can be no governmental regulation of bioplastics.
However, the United States Department of Agriculture proposed a definition of bio-based in 2016, which is relevant to understanding what bioplastic means.
According to the USDA, a product must contain a minimum of 25% carbon from biological sources to be called bio-based. Biological sources include agricultural residues like corn or sugarcane stalks. They could also come from marine or forestry materials. This rule implies that up to 75% of the carbon in a bioplastic can come from fossil fuel sources!
However, there are exceptions. For example, the chemical company BASF invented Ecoflex, made of polybutylene adipate terephthalate (PBAT). It is a 100% fossil fuel-derived plastic, but BASF calls it a bioplastic. The reason is that it happens to be biodegradable. In other words, PBAT is a “bioplastic” made completely of non-renewable fossil fuels because it is biodegradable.
However, I’m not convinced this is true. A 2017 study showed that Ecoflex immersed for one year in artificial sea or freshwater did not break down at all.
Is There a Legal Definition of Biodegradability?
Unfortunately, there is no legal definition of biodegradability. This leads to companies using the term loosely, adding to the confusion.
The USDA does not mention this in its BioPreferred program or anywhere else. Nor does any other governmental agency.
You may naturally be led to believe that if something is 100% bio-based, then it will most certainly biodegrade. This is probably true.
What is unclear is if products less than 100% bio-based will biodegrade. Since almost all bioplastics are <100% bio-based, this is a relevant question.
To limit the confusion surrounding what’s biodegradable—and prevent greenwashing marketing tactics by companies—some states have passed laws concerning biodegradability. California, Maryland, Washington, and Minnesota have restricted use of the word biodegradable and similar words so they won’t mislead shoppers.
The Federal Trade Commission (FTC) publishes Green Guides to help consumers understand terms like biodegrade so they won’t be misled. Unfortunately, the FTC guidelines are not legally enforceable. Lacking federal standards, many states use the Green Guides to set policy.
Here’s a short video by the FTC to help you understand the Green Guides.
History of Bioplastics
You may think that bioplastics are a recent invention. It seems everywhere you turn there are fossil fuel-derived plastics but hardly any bioplastics.
If you’ve made this observation, you’re correct.
According to the nonprofit Plastic Oceans International, more than a dump truck full of traditional fossil fuel-derived plastic enters the oceans every minute of every day. That’s roughly 10 million tons per year degrading into literally trillions of tiny micro- and nanoplastic particles that never fully break down.
However, you might be surprised to find out that bioplastics are not actually new. In 1862, Alexander Parkes invented the first bioplastic from cellulose, aptly naming it cellophane.
Then in 1897, German chemists used the dairy milk protein casein to invent a bioplastic called galilith. It is still used today to make artisanal buttons.
In the 1930s, Henry Ford used soy to make car parts for over a decade. His early success in making bioplastics ended quickly after World War II.
Well, an overabundance of cheap oil shifted industries’ focus to the exclusive use of fossil fuels to make many different types of plastic for every conceivable purpose. It remained that way until the 1970s’ oil embargo which made the price of oil skyrocket.
Then companies began seriously researching alternative materials to make plastic so they could maintain high-profit margins. But, a glut of oil in the ‘80s marketplace—and falling prices—caused a near-total return to non-renewable plastic for making consumer goods.
In 1983, Marlborough Biopolymers used bacteria to create plastics and were successful for a short while. By 1990, however, plants became the preferred material for bioplastics.
Cargill and Dow entered into a joint venture to produce bioplastics using corn in 1997. Four years later, they introduced polylactic acid (PLA), which is the leading bioplastic used today.
Fast forward 20 years to growing public awareness of the causative role of burning fossil fuels—for energy and transportation as well as to make plastics—as the major reason for the climate crisis. Coming under increasing scrutiny, the plastics industry sought ways to improve its image.
As coal use declines this decade, at least in some countries, the fossil fuel industry is turning to plastics to make up the shortfall. Marketing blends of petrochemicals with plant-based materials as eco-friendly is now a major tactic for meeting this objective. So is using the abundance of methane gas discovered via fracking.
What Are the Major Types of Bioplastics?
There are two major types of bioplastics used today:
1. Polylactic Acid (PLA)
PLA (polylactide) is made of sugars sourced from corn starch, cassava, or sugarcane. To make one pound of PLA, roughly 3 pounds of corn are required.
You can see that if most fossil fuel-based plastics were replaced with PLA, it could compromise food security of this staple crop, already experiencing significantly lower yields due to extreme drought and heat waves in many countries. This is especially true since 45% of the corn crop in the U.S. is already used for biofuel (ethanol) in cars.
PLA is used as a substitute for five of the major types of fossil fuel-based plastics:
- Polyethylene (#1, #2, #4)
- Polypropylene (#5)
- Polystyrene (#6)
In the open air, PLA takes 80 years to biodegrade. So, you may not see it disappear in your backyard compost pile, but maybe your children will when they are senior citizens.
2. Polyhydroxyalkanoates (PHAs)
Rather than chemical reactions, PHAs are produced by genetically engineered bacteria and algae. These microbes store PHA in their cells for up to 80% of their cell volume. Food waste or liquefied plastic waste can be used as growth media for the microbes. There are many similar compounds in the PHA group with varying characteristics that could be used to replace fossil plastics. Research into PHAs is ongoing.
Currently, there are not many companies making PHA, although some analysts say this will change soon. Hopefully, it won’t take 23 years to turn a profit like it did for the leading PLA manufacturer, NatureWorks.
What Are Bioplastics Used in?
Bioplastics are found in many items including:
- Packaging materials
- Plastic wrap
- Restaurant food takeout (clamshell) containers
- Cutlery and straws
- Bags (candy, snacks, food waste, teabags, etc.)
- Paper cup coatings
- Phone casings
- 3D printing
- Car parts
- Medical implants
- Surgical sutures
Case Study: Coca-Cola’s PlantBottle
As the largest company selling its products in single-use plastic bottles, Coca-Cola was increasingly criticized for generating huge amounts of plastic pollution. So, in 2009, they launched the first bioplastic version of a bottle containing 30% sugarcane residues and 70% fossil fuel derivatives.
By mid-June 2015, they had sold 35 billion PlantBottles in approximately 40 countries. To place this number in context, the company produces more than 100 billion plastic bottles per year. In a 2019 press release, Coca-Cola said their bioplastic bottle was used in 7% of all their products sold globally.
Then Coca-Cola hired three companies to create different materials used in PlantBottle 2.0, a bottle made completely with plant-based chemicals. Called bio-PET, it is chemically identical to regular plastic type #1 (r-PET).
Bio-PET is called a drop-in plastic because it can be dropped in as a direct replacement for r-PET. This means bio-PET bioplastic will take as long to break down in the environment as r-PET. When it does, it will release micro- and nanoplastics. Either type of PET bottle is not biodegradable even though bio-PET is 100% plant-based.
Bio-PET can be recycled in conventional recycling plants along with r-PET. However, less than 5% of all plastic is recycled in the United States. So most bio-PET heads to the landfill, is incinerated, or winds up as ocean pollution.
Coca-Cola presented a PlantBottle 2.0 prototype to the public in 2015. The process took years to finalize and scale. Finally, it was rolled out in 2021 in select areas.
The only chemical difference between the polyethylene in bio-PET and regular polyethylene (r-PET) relates to the starting materials in the reactions used to form them. For bio-PET, plant-based ethanol is used to replace the fossil fuel-sourced ethylene in r-PET. Both raw materials can be used to make the same plastic.
Even with this technology, Coca-Cola does not intend to stop using fossil fuels and make just bio-PET bottles. Why is that?
Why Haven’t Bioplastics Replaced Fossil Fuel Plastic?
You’d think a commodity expected to triple in value to almost $30 billion by 2028 would have a large market share. Especially if that commodity reduces climate crisis-driving carbon emissions by 30-70% and uses 65% less energy compared to the production of conventional plastic made with fossil fuels.
Unfortunately, bioplastics represent only 1% of all plastic sales.
The reason for this statistic is likely economic. It costs 20% to 100% more to manufacture bioplastics compared to fossil plastics. Since companies will pass this increase onto shoppers, only those in the highest income brackets will be able to afford bioplastics. Knowing there’s a high likelihood that bioplastics won’t be profitable, companies aren’t willing to take the risk.
Since there are so few bioplastic products on the market (compared to fossil plastics), it’s no surprise that the infrastructure needed to compost or recycle bioplastics isn’t readily available. This means they are incinerated or end up in a landfill.
If released into the environment, bioplastic may wreak havoc just as conventional plastic does. This includes entangling wildlife or degrading into microplastics, which can negatively affect the health of the whole ecosystem (including humans).
From this discussion, it’s clear that the most eco-friendly action you can take regarding plastic is to avoid purchasing all single-use plastic, both fossil and bio-based plastic. Reusable alternatives, like cloth bags or stainless steel water bottles, are more sustainable than either type of plastic.
Are Bioplastics More Sustainable (and/or Less Toxic) Than Fossil Fuel Plastics?
Bioplastics are NOT inherently more sustainable than conventional plastics made entirely of fossil fuels.
A 2010 study revealed that overall, in a life cycle assessment comparing conventional plastics and bioplastics, b-PET made with both plant and fossil fuel sources was the least sustainable plastic. It scored the lowest because of the carbon-intensive agricultural and chemical processes needed to make it.
According to the study, it was also most likely to cause toxic effects in ecosystems and had the greatest potential to contain or transport the most carcinogenic substances.
Can Bioplastics Be Recycled?
In theory, bioplastics are recyclable. However, recycling bioplastics requires specialized equipment that is not commonplace in most states. Recycling plants that can handle bioplastics are very expensive to build especially for something that represents only 1% of all plastics currently used. Since it’s not cost-effective to recycle them, bioplastics are landfilled or incinerated along with the large majority of plastics.
Most fossil fuel-baased plastics will be incinerated or landfilled after they’re recycled once. Since only less than 5% of all plastic is recycled, most bio-PET, which is a mere fraction of that, will not be recycled.
Bioplastics that contain less than 100% plant material cannot be recycled in conventional recycling plants. Mixing them in with fossil fuel-derived types #1 or #2 plastic which can be recycled at most plants adds to the cost of recycling. Bioplastics are considered contaminants in the recycling stream and must be sorted out first. If they don’t get separated out, their passage in recycling machinery built to handle solid waste exclusively sourced from fossil fuels could cause damage.
At the present time, there are very few recycling plants in the world that accept the large majority of bioplastics made with less than 100% plant materials.
In light of this information, only if recycling bioplastics becomes customary in most places could buying them ever be considered sustainable. At least fossil plastics #1 and #2 stand a real chance of actually being recycled today, although it’s a slim chance.
How Can You Reduce Plastic Pollution?
While one person can’t reverse the trend of more and more plastic pollution heading to the landfill or the ocean—especially with more plastic factories being built or planned worldwide—you can still take steps to make a small difference:
- Voice your concerns to your local officials and your Congressional representatives until plastics recycling becomes commonplace in your area.
- Demand that your favorite brands invest in bioplastics companies working on making plastics that are actually fully biodegradable (and within a reasonable amount of time).
- Reduce or eliminate your consumption of plastic by choosing non-plastic alternatives when you can.
Final Thoughts on Bioplastics
Bioplastics make up only 1% of all plastics used today but they are expected to triple their market share this decade. Bolstering this increase are large companies like Coca-Cola and Heinz packaging some of their products in 100% bio-PET (plastic type #1) bottles.
Bio-PET bottles are branded as renewable, but this is misleading. The plastics industry likely uses the term to offset negative press about the similar word non-renewable, which is usually used to describe traditional PET (r-PET) plastic bottles made with non-renewable, carbon-emitting fossil fuels.
PET bottles made of 100% plant materials can be recycled like r-PET bottles. But they both are downcycled to make lower-quality items such as park benches or plant containers.
Like their fossil fuel-derived analogs, bio-PET bottles are not biodegradable even though they are technically bioplastic. Unlike what you may be led to believe from companies who claim their bioplastics are biodegradable, today’s bioplastics will not biodegrade in a few months or less under typical backyard conditions.
For more on biodegradability vs. compostability in bioplastics, see our article here.