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The dirt on compostable plastics


The Sonoma Compost Company is just off Highway 101, northwest of Petaluma. All day, trucks haul in plant materials; others haul out soil. Sift through that soil, and you might find remnants of chicken feathers (apparently great for vegetable growers), rice hulls (nice for clay soils), and more.

Will Bakx is the owner and operator of the facility. To his mind, those incoming trucks are carrying two types of things. There’s plant material and food scraps from kitchens and yards across Sonoma County. That’s what the trucks are supposed to be carrying. Then there’s what they’re not supposed to be carrying: plastic. “It’s a real problem,” Bakx says.

Bakx has been operating the Petaluma facility for 26 years. It processes about 300 tons of green waste a day – about 1,000 pickup trucks full. In the last few years, though, Bakx and his crew have noticed an increasing amount of what’s known as compostable plastic.

“We have over here about five to six people working on the sorting before it goes to the grinder,” Bakx explains. “And then I still have one to two people cleaning up between the wind rows out here of compost.”

Here’s the thing: Bakx doesn't take plastics – not any plastics. Instead his employees spend lots of time picking out those supposedly compostable forks and bags and throwing them in the trash.

That’s right: If you dropped it in the compost bin in Sonoma County, the compostable fork you felt so good about using probably went to the landfill. Bakx explains that when compost includes plastics, the resulting soil isn't considered organic. That means it can't be sold to organic farmers.

“It is extremely effective in consumer confidence when they see you go through the efforts to meet the standards for organic growing,” he says. “It really enhances the confidence they have in my materials.”

Apart from wanting to stay organic, Bakx has a lot of hesitation about compostable plastics. He says they used to be made exclusively from plants, but that’s changed as the industry has grown. These days, compostable plastics are often made out of oil-derived material, and many are 100% petroleum based. When asked how these supposedly-compostable products could be petroleum-based, Bakx answers, “The molecular structure is such that the microbes can consume it.”

In other words, it isn’t identical to oil, but it’s derived from it.

The city of San Francisco sees plastics in its compost differently.

“There’s almost no difference between a corn cob going in on one end with a corn cup and both coming out as finished compost,” says Jack Macy, the city’s commercial zero waste coordinator.

Like a growing number of cities, San Francisco is trying to divert as much waste away from landfills as possible.  A plastic that is fully compostable – meaning it can be consumed by organisms within 180 days – achieves that goal.  So San Francisco will take any plastic that meets this compostability standard, no matter what it’s made from.

Macy does have some concerns, mostly on consumer confusion about plastics. Companies like Coca Cola now offer plastic bottles that they advertise as plant-based. They’re not compostable, but the big green leaf on the logo might make you think otherwise.

“Well just because it's plant based doesn’t actually change the final chemistry of that bottle and it's just as if it was made from petroleum so it's not compostable in any meaningful sense,” Macy says.

His other concern is over labeling.

“If you see the word ‘degradable’ or ‘biodegradable,’ you should be very wary and not consider it compostable and really not use it,” he says.

Under a 2008 California law, plastics can't be labeled “biodegradable” and can only be labeled “compostable” if they meet specific standards, like completely breaking down within six months. Even so, many companies use the word “biodegradable” freely. This past October, Attorney General Kamala Harris put some teeth in the legislation, filing suit against three water bottle companies for mislabeling. Macy says consumers shouldn’t let themselves be tricked.

“To the extent that it might break down, it's even worse in a landfill,” he says. “So it's not recyclable, it's not compostable, it's worse for the landfill, it's just as bad as litter, there's no benefit to its end of life. It's a greenwash and don't waste your money on it.”

There’s a lot of money at stake, though. Plastics that meet the compostable standard are more expensive. At Costco, 1,000 compostable forks cost nearly $65, while 1,000 regular plastic forks are $37. Will Bakx, of Sonoma Compost, says this makes it even more important for people to know exactly what they’re buying.

“For the consumer it is important because they are paying extra money for this product,” Bakx says. “And you know it's like, are they just wasting this? Literally taking it to the landfill? Or is it a good thing that they're doing?”

Bakx also questions the whole concept of growing plastic from plants, just to turn it back into soil.
All the embedded energy of making it – growing the corn where you have heavy fertilizer, heavy pesticide, heavy water use, then it needs to be processed, then there's the transportation – all of that energy is destroyed in the composting process,” Bakx says.

And at that point, he points out, composting those plastics might not even be worth it. One might opt for recycling than composting, then.

Every day we make decisions based on our environmental values. A wooden stirrer or a compostable plastic one to mix your to-go coffee? Organic vegetables or local ones? We want the decisions to be straightforward – but sometimes they’re not.

“I think that people come from a good place,” Bakx says. “I think that most of us here particularly in the Bay Area, feel that whatever we can do to make a better environment, we are willing to pay a little extra for that. And so when you see compostable plastics, everyone knows compost is good for the earth, naturally we feel like we're doing the right thing. But if the consumer does not know that these products may not break down.

The U.S Composting Council is studying the impacts of compostable plastics. So in a few years, we may see new standards for what it means to say a plastic is compostable. But for now, with everybody eager to save the earth, it's composters like Will Bakx who are left holding the proverbial compostable trash bag.

This story originally aired January 24, 2012.

Hadley Robinson is a reporter with the UC Berkeley Graduate School of Journalism.