Corn Plastic to the Rescue

Wal-Mart and others are going green with “biodegradable” packaging made from corn. But is this really the answer to America’s throwaway culture?

Nature Works has figured out how to make plastic out of corn. (Ex0artefact)
Smithsonian Magazine | Subscribe

(Continued from page 2)

NatureWorks has given this problem some thought. “If the MRF separates the PLA, we’ll buy it back from them when they’ve got enough to fill a truck,” says spokeswoman Bridget Charon. The company will then either take the PLA to an industrial composter or haul it back to Blair, where the polymer will be broken down and remade into fresh PLA.

Despite PLA’s potential as an environmentally friendly material, it seems clear that a great deal of corn packaging, probably the majority of it, will end up in landfills. And there’s no evidence it will break down there any faster or more thoroughly than PET or any other form of plastic. Glenn Johnston, manager of global regulatory affairs for NatureWorks, says that a PLA container dumped in a landfill will last “as long as a PET bottle.” No one knows for sure how long that is, but estimates range from 100 to 1,000 years.

Environmentalists have other objections to PLA. Lester Brown, president of the Earth Policy Institute, questions the morality of turning a foodstuff into packaging when so many people in the world are hungry. “Already we’re converting 12 percent of the U.S. grain harvest to ethanol,” he says. The USDA projects that figure will rise to 23 percent by 2014. “How much corn do we want to convert to nonfood products?” In addition, most of the corn that NatureWorks uses to make PLA resin is genetically modified to resist pests, and some environmentalists oppose the use of such crops, claiming they will contaminate conventional crops or disrupt local ecosystems. Other critics point to the steep environmental toll of industrially grown corn. The cultivation of corn uses more nitrogen fertilizer, more herbicides and more insecticides than any other U.S. crop; those practices contribute to soil erosion and water pollution when nitrogen runs off fields into streams and rivers.

NatureWorks, acknowledging some of those criticisms, points out that the corn it uses is low-grade animal feed not intended for human use. And it processes a small amount of non-genetically engineered corn for customers who request it. NatureWorks is also investigating better ways to segregate PLA in traditional recycling facilities, and it’s even buying renewable energy certificates (investments in wind power) to offset its use of fossil fuels. But there’s not much the company can do about the most fundamental question about corn plastic containers: Are they really necessary?

A few miles south of Blair, in Fort Calhoun, Wilkinson Industries occupies a sprawling, low brick building in a residential neighborhood. Wilkinson converts NatureWorks resin into packaging. In a warehouse-size room, the pellets are melted, pressed into a thin film and stretched into sheets that a thermoformer stamps into rigid containers—square, tall, rectangular or round. (PLA can also take the shape of labels, electronics casings, wrap for flowers, gift cards, clothing fiber and pillow stuffing.) “We’re shipping trays to Google’s cafeteria and to [filmmaker] George Lucas’ studio in San Francisco,” says Joe Selzer, a Wilkinson vice president. “We do trays for Del Monte’s and Meijer stores’ fresh cut fruit. And, oh yeah, we do Wal-Mart.”

PLA amounts to about 20 percent of the plastic products made by Wilkinson. The rest is polystyrene and PET. “We’d like to see PLA be the resin of the future, but we know it never will be,” says Selzer. “It’s cost stable, but it can’t go above 114 degrees. I’ve had people call me and say, ‘Oh my god, I had my takeout box in my car in the sun and it melted into a pancake!’” Bridget Charon, sitting next to me, raises an eyebrow. Selzer continues. “Our number-one concern is PLA’s competitive price, and then its applications. After that comes the feel-good.”

Selzer leads us up a staircase to an interior room the size of a large pantry. It’s crammed with samples of the 450 different containers fabricated by Wilkinson, which also stamps out aluminum trays. “Here’s Kentucky Fried Chicken’s potpie,” Selzer says, pointing to a small round tin. “This plastic tray is for a wedding cake. This one’s for crudités. This is for cut pineapple.” (Wilkinson manufactured the original TV dinner tray, a sample of which resides in the Smithsonian Institution.) As I look around, I can’t help thinking that almost all these products will be dumped, after just an hour or two of use, straight into a big hole in the ground.

Martin Bourque, executive director of the Berkeley Ecology Center, a nonprofit recycling organization, holds a dim view of PLA convenience packaging. “Yes, corn-based packaging is better than petroleum-based packaging for absolutely necessary plastics that aren’t already successfully recycled, and for packaging that cannot be made of paper,” he says. “But it’s not as good as asking, ‘Why are we using so many containers?’ My worry is that PLA legitimizes single-serving, over-packaged products.”


Comment on this Story

comments powered by Disqus