Although bioplastics contain biological ingredients, not all are compostable or even biodegradable. Learn the difference between bioplastics and which ones offer promise to the world’s plastic problem.
Since the 1950s the world has produced, used, and thrown away more than nine billion tons of plastic. As images of our plastic-clogged oceans surface, alternatives have emerged to these petroleum-based products.
But are these new plastics any better, or do they come with some of the same problems as conventional plastic? The merits of bioplastics are tempered by many conditions. Here’s what you need to know.
Related: Ocean Plastic Pollution – Here’s How You Can Help
What are bioplastics?
Bioplastics are plastics that contain some ingredients from renewable biological sources, such as vegetable fats, plant starches and wood fibres. These bio-based plastics fall into two main categories.
PLA (polylactic acids)
PLA is a form of polyester made by fermenting ingredients like corn starch or sugar cane. This is currently the cheapest bioplastic on the market. It’s commonly found in food packaging, clothing, cosmetics, and home furnishings. PLA is often more brittle than regular plastic and doesn’t stand up well to heat.
PHA (polyhydroxyalkanoates)
PHA is a form of polyester created and stored by bacteria when fermenting sugar or fats. When used in bioplastics, PHA can withstand higher temperatures than PLA. Today you’ll find PHAs in food packaging, agricultural products, and medical devices.
Related: The Best Alternatives for the Plastic in Your Life
The pros and cons of bio-based plastics
While creating plastics from renewable sources is an improvement over petroleum-based plastics, there are some drawbacks.
Many bioplastics are not readily biodegradable and must be processed in special facilities to break down. That means most products containing bio-based plastics must be separated from your regular garbage and recycling. You must return these to a special facility that deals with bio-based plastics. Most municipalities don’t yet have these in place. Improper disposal can create another environmental problem.
If a bioplastic enters the landfill, it can take 10 to 1,000 years to break down. If it ends up with your recycled plastic, it can contaminate items that are otherwise recyclable. You heard that right: a bioplastic product tossed in with your plastic recycling can wreck the whole batch. And if it ends up in the ocean? In most cases, it behaves the same as regular plastic.
If a bioplastic enters the landfill, it can take 10 to 1,000 years to break down. If it ends up with your recycled plastic, it can contaminate items that are otherwise recyclable.
Plus, bioplastics aren’t usually 100% vegetable matter. Sometimes they can be as little as 20%. The rest could be conventional materials. It all depends on the type of bioplastic.
Yet the use of bioplastics can reduce greenhouse gas emissions. Creating a substance like PLA requires less energy than conventional plastics like PET or Styrofoam. That means PLA produces less carbon dioxide during its production. It also produces fewer greenhouse gases when it biodegrades in the landfill than some other plastics. Additionally, some bioplastics use less water during production than conventional choices.
Related: Plastics by the Numbers
Biodegradable vs. compostable plastic
But what about bio-based plastics that claim to be ‘compostable’? What’s the difference between biodegradable and compostable when it comes to plant-based plastics?
A biodegradable material is anything that breaks down from the action of microorganisms like bacteria, algae and fungi. Degrading time depends on moisture and temperature, along with the materials in the product.
Although made from plant, animal, or mineral based substances, biodegradable bioplastics don’t always break down completely into their natural components. Sometimes they leave residues behind.
Under the right conditions, microorganisms can convert biodegradable bioplastics into water and carbon dioxide in a few weeks. But many biodegradable products may still contain conventional plastic, making them more difficult to break down.
A compostable material is anything that decomposes completely into natural materials like water, carbon dioxide, and biomass within about 90 days. Compostable materials will eventually turn into nutrients that can be used by plants. They won’t leave behind any residues.
Related: How to Use Finished Compost
Bioplastic classifications
Bioplastics come with a lot of claims regarding their eco-friendly properties. Let’s break down some of the most common descriptions a little further.
1. Non-biodegradable bioplastics (BIO-PET, BIO-PE, PA)
These bioplastics aren’t easily digested by microorganisms. Although made from natural materials like sugar cane, they are chemically identical to some petroleum-based plastics. Like conventional plastic, they will only degrade after many years.
2. Partially biodegradable or “durable” bioplastics
Microrganisms can break these down into smaller pieces of plastic under the right conditions. Unfortunately the process generally takes longer than 3-6 months. “Break down” is not the same as “decompose,” so these bioplastics are not compostable.
3. Biodegradable bioplastics
As noted above, biodegradable plastics will break down into carbon and water due to the work of microorganisms. The best biodegradable products will indicate a time frame and the conditions required to achieve biodegradation.
4. Compostable plastics
Most of these plastics need industrial facilities to fully decompose. Some carry the claim that they will break down in the home compost, but this isn’t yet the norm.
What should I do with bioplastic products? Can I recycle them?
In most places you can’t recycle products made from bio-based plastics. That’s because it’s tricky to separate all the components. So while it’s technically possible to recycle bio-plastics, most facilities don’t accept them. They won’t until there are more of them to process. Here’s what you should do instead.
Biodegradable plastic products
Unless facilities exist in your area for dealing with bio-plastics, put these in your regular trash bin.
Compostable bioplastic products
Put these in your municipal food waste bin if available. Don’t put compostable bioplastics in the landfill since they won’t compost well in this low oxygen environment. Even worse, they’ve been shown to produce methane, a greenhouse gas 30 times more potent than carbon dioxide.
Are there bioplastic composting facilities in my area?
As noted above, most bio-based plastics require specific conditions to break down completely. While some carry the claim that you can throw them into your home compost, most do not. Home composts don’t usually get hot enough to break down compostable, bio-based plastics.
To find out if your municipality has a facility for processing bioplastics, visit
http://findacomposter.com/and type in your location. If no facility exists, your bioplastics will likely end up in the landfill.
What happens to bio-based plastics in the landfill?
The law requires landfills to be airtight, blocking out water, light and air. These are the same things needed to naturally break down biodegradable and compostable materials.
Unfortunately in landfills, bioplastics take many years to break down. They can even hinder the breakdown process of other trash, depending on their content. As noted above, compostable bioplastics can produce methane in this low oxygen environment.
Related: How to Reduce Plastic Pollution in 15 Easy Swaps
Can we use bioplastics to generate power?
Some types of bioplastics are suitable for generating power through bioenergy. According to the US Department of Energy, there are three ways to harvest the energy stored in biological waste:
- Burning
- Bacterial decay
- Conversion to a gas or liquid fuel
To date, there aren’t dedicated facilities in North America specifically designed to convert bioplastic waste into energy. This may change in the future.
Related: Eartheasy Guide to BioFuels
What about the overall footprint?
Some specialists feel that bio-plastics are better for the environment, even if they end up in the landfill. That’s because they’re made from materials other than petroleum. In general, bioplastics contain fewer ingredients from fossil fuels. Some contain none at all.
Displacing fossil fuels with renewable resources is a positive step. Under the right conditions, bioplastics produce less greenhouse gas emissions than petroleum-based plastics. The problem comes when calculating the overall footprint of each product.
Various studies have shown that some bio-based plastics can have a greater impact on the planet than conventional products. That’s because producing the plants needed for bioplastics involves chemical fertilizers and pesticides, along with chemical processing. When the negative effects of agricultural production combine with the chemical processes needed to convert plant matter, some bioplastics are less environmentally friendly than regular plastic.
Are bioplastics good?
Bio-based plastics are not a solution to end plastic waste. Too many of these products contain regular plastic. Others don’t decompose in a reasonable time frame and leave us with the same disposal problem we have with conventional plastic: too much, too quickly. Using bioplastic disposables to continue our throwaway habits doesn’t make sense.
Where these new plastics do make gains is when they’re used as lightweight, reusable alternatives to single-use plastic. Many bioplastic products now exist to replace single-use items like food containers. These can keep thousands of pounds of plastic trash from entering landfills and oceans. And they can help cut down on greenhouse gas emissions.
Reusable food containers are just one of the many ways to reduce single-use plastic.
Where industrial composting facilities exist, compostable bioplastics are the most environmentally friendly choice. These natural-based plastics decompose completely, though most must end up in a high-heat composting facility.
The best choice of all is to avoid disposable plastics all together. Instead, enjoy the many reusable zero waste products made from renewable and recyclable materials. Find alternatives to plastic wrap, bulk food and produce bags, and shopping bags.
Related: 5 Plastic Straw Alternatives to Use Right Now
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