Which is better for the environment: Compostable bioplastics or PET? The answer may surprise you: Page 2 of 2

In the context of real-world recycling practices, in which waste materials are separated (imperfectly) by a combination of automated and manual methods, the most effective way of keeping biodegradable or compostable plastics separate from traditional plastics is to use the two types of materials in different product applications. 

Context matters. Traditional, recyclable PET is perhaps best used to make products that typically get recycled, such as bottles and food containers. Biodegradable and compostable plastics perhaps should be limited to products such as agriculture film used to hold in moisture, which can be plowed under at the end of the growing season.

Compostable plastics are biobased materials designed to break down into the soil along with food and yard waste, but they often don’t achieve that goal. While it sounds fantastic in theory, many compost facility owners say it’s not that simple. Plastics that are designated as compostable must be composted in an industrial or commercial composting facility, not a backyard compost bin. However, there are a number of problems associated with composting so-called compostable plastic, even in commercial facilities. 

First, compostable products are generally not taken curbside—you must find a composting facility and take your compostables to them. While most large cities have municipal commercial composting facilities for yard and food waste, very few will actually take compostable plastic waste. Many compostable plastics will not compost in the short amount of time required by the facility, and the material won’t break down fast enough or small enough that it cannot be seen in the compost. Just ask the residents of Portland, OR, or Berkeley, CA, two cities that have banned compostable plastics from their composting facilities, and they will likely tell you their desire to be eco-friendly died on the vine.

Most composting facility owners I have interviewed are skeptical of compostable plastics. They will tell you they’ve not had good luck with compostable plastic cutlery, cups and containers, and are reluctant to accept plastic material that claims to be compostable.

Recyclable plastics use fewer resources over their entire lifespan than any alternative single-use material, and plastics’ eco-friendliness has been proven by many studies. Many brand owners choose “green” sounding materials as a means of “virtue signaling,” not because they are better than traditional recyclable materials such as PET.

One could argue that, despite the creation of polymers with seemingly environmentally friendly names—compostable and biodegradable—the polymer that perhaps sounds the worst could indeed be the best: Polyethylene terephthalate (PET). As industry experts continue to educate consumers and customers, people are starting to understand the science. Just because something sounds eco-friendly does not mean it is ecologically better. 

Image: Blende11.photo/Adobe Stock

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