Sustainable America Blog

The Compostable Cup Conundrum

Compostable PLA cups made from corn

At Sustainable America, we have found that with education and increased awareness, people can make better decisions. Most of the time this is easy to communicate. But sometimes, choice can be confusing. A prime example that we have wrestled with when we help events reduce waste is the compostable, or polylactic acid (PLA), cup.

Wait, Compostable Cups Are a Great Idea, Right?
At first blush, yes, compostable cups seem like a great idea. Typically made out of corn starch, PLA cups are better in terms of greenhouse gas emissions since the corn used to create them captured carbon dioxide from the atmosphere as it grew, and the cup, if composted, can enrich soil. With a desire to minimize the amount of waste that goes to the landfill and instead divert it to compost, it seems obvious that cups made out of organic material would be better than cups made out of plastic derived from oil.

So What’s the Problem with Compostable Cups?
If they are sent to an industrial-scale composting facility with actively managed piles of compost under controlled conditions, and fed a diet of digestive microbes, PLA cups will break down in less than two months. In someone’s backyard compost heap, it could easily take more than a year. If they are accidentally sent to a landfill and buried, it could take over a century. And if they go into a plastics recycling bin, they will contaminate the recycling process.

And that’s the heart of the problem.

The vast majority of PLA cups in the U.S. are indistinguishable from clear plastic, recyclable cups, other than being marked with a big green stripe. They are the same size and shape, they hold liquids the same way, and no ordinary consumer would have any reason to guess that they are different. If anything, they might look at the green stripe as a reminder that plastic should be recycled!

Recently, I had the privilege of speaking at the American Community Garden Association Conference about our newest project Shared Earth. The event was held at the Field Museum in Chicago, and their restaurant, the Explorer’s Café, is a Founding Member and Gold Partner in the Illinois Food Scrap Coalition, a group of organizations dedicated to advancing food scrap composting in Illinois. They source as much food as they can locally, and much of the food is served in compostable materials, including PLA cups. They also have three bins for waste – recyclable, compostable, and landfill.

As I ate lunch at the café, I watched as one guest after another tossed PLA cups into the plastics recycling bin. As soon as I finished my lunch, I held forth for a while by the trash bins, instructing guests that the cups would be harmful to the recycling process, which is set up to recycle oil-based plastics. (The converse is also true, that plastic cups should not be put into the composting bins.) Ultimately, however, I had to return to the conference, and I am sure that without someone standing there by the bins, more and more contamination happened during the course of the day. Despite a well-educated crowd and great signage at the restaurant, there was a great deal of confusion, and from my observations, most were guessing wrong.

Can We Do Better? Yes!
Now that you know more about the PLA cup, you will probably make the right choice next time you’re faced with which bin to put it in, but the issues I witnessed at the Field Museum illustrate how far we have to go when it comes to educating the general public about recycling and composting.

I commend businesses that are on the cutting edge of composting, but along with that comes an obligation to educate and train customers about what to do with their cups, plates and food scraps. That means very clear signage, and maybe even verbal instructions or stationing an employee at the trash station. (That’s what we’ve found works best at the events we’ve helped implement compost collections.) Teaching the public about composting procedures is hard work. For many people, it’s a completely new concept. But as it becomes more common, we will slowly and surely make a difference.

If you agree that we need to do more to educate the public about composting, help us by donating to Sustainable America today! Donations as small as $10 make a difference!

Jeremy Kranowitz
Executive Director, Sustainable America

RELATED ARTICLES
How Much Corn Should We Put in Our Fuel Tanks? (Video)
3 Golden Rules of Recycling
Staff Challenge: Go “Zero-Waste” for a Month

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By the Numbers

Currently 50 million households suffer from food insecurity, meaning that family members cannot always meet their basic food needs.

10 million people a year could be fed through the recovery of just one-fifth of food waste.

Only 2% of food waste is composted or otherwise recycled—62% of paper is recycled.

Consumers throw out about 40% of the fresh and frozen fish they buy.

The U.S. produced 208 pounds of meat per person in 2009—60% more than Europe.

Low income commuters spend a much higher proportion of their wages on gas—8.6% versus 2.1% at $4 per gallon.

Food prices rose 35-40 percentage points between 2002–2008.

Americans consume 25% of the world’s produced oil, but our nation holds less than 3% of the world’s proven oil reserves.

The International Energy Agency says greenhouse gas emissions rose 3.2% last year, with a 9.3% increase in China offsetting declines in the US and EU.


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