Biodegradable plastic made from plants, not oil, is emerging

ByRon Barnett, USA TODAY
December 25, 2008, 7:48 PM

— -- Here is one word about an up-and-coming innovation in plastics: cornfields.

Bioplastics — most of which are now made from corn — are poised to grab a bigger share of the plastics market as concerns about the environment and U.S. dependence on foreign oil promote alternatives to products made from petrochemicals.

They already are showing up in a variety of products, such as plastic gift cards, food containers and cellphone casings, says Steve Davies, a spokesman for NatureWorks.

NatureWorks, based in Minnetonka, Minn., developed one of the first plant-based plastics with the creation of a resin technology called Ingeo. Its Ingeo plastic pellets are used to make clothing, diapers and food-packaging material.

After doubling the size of its manufacturing plant in Nebraska, NatureWorks will have the capacity to produce up to 300 million pounds of pellets a year.

Research by NatureWorks, a subsidiary of agribusiness giant Cargill and Teijin of Japan, indicates a future market demand of up to 50 billion pounds of bioplastics a year within two to five years. That would represent about a 10% share of the global plastics market.

Among the first companies to turn to biodegradable plastic in a big way is Naturally Iowa, an organic dairy that makes milk and water bottles out of pellets from NatureWorks, says William Horner, Naturally Iowa's CEO.

"This is one of the greatest hidden sources of replacing petroleum that we've got," Horner says.

"The cost of the bottles is 5% to 10% higher than regular plastic bottles, but it's worth it both environmentally and economically in the long run," he says. "When you compare the cost for disposal of plastic to the cost of disposal of a compostable bottle, all of a sudden the cost levels out."

Although the plastic is biodegradable, disposing of it is not necessarily as simple as throwing your bioplastic bottles onto your backyard compost heap, says Betty McLaughlin, executive director of the non-profit Container Recycling Institute.

The basic ingredient of corn-based plastics is polylactide, or PLA. Most PLA has to go to a commercial composting plant to be decomposed, she says. Although PLA can be recycled for use in other products, it can't be recycled along with regular petroleum-based plastics.

"It sounds great," McLaughlin says. "It's renewable, biodegradable and all that kind of stuff. But the practical matter is that you still have to grow the corn to extract the sugar from. And how many pesticides do you need to put into the soil to grow the corn?"

It's an open question, she says, whether it's more energy efficient to use biodegradable plastic or to recycle petroleum-based plastic.

Researchers are finding ways to address some of those problems, though.

Cambridge, Mass.-based Metabolix has developed a brand of biodegradable plastic called Mirel that decomposes in soil, compost or even water, says Brian Igoe, chief brand officer. It's made from genetically engineered microbes that convert corn sugar into polymers in a fermentation process.

Metabolix has engineered a switch-grass crop that actually grows plastic inside its leaves and stems, but that product is still a few years away, Igoe says.

Mirel costs about twice as much as petroleum-based plastic, so the company markets it for such uses as packaging for natural cosmetics, or agricultural mulch film that can be tilled into the soil to eliminate waste and cut costs, Igoe says.

The company has a joint venture with Archer Daniels Midland adm called Telles, which is building a plant in Iowa that will go into operation next year with the capacity to produce 110 million pounds of Mirel annually, he says.

Researchers at Clemson University in South Carolina have come up with solutions to some of the main technical drawbacks of bioplastics.

For example, molecules such as water can slip through corn-based plastic, which means that the water would evaporate out of such a bottle over time, says Danny Roberts, one of the Clemson scientists who developed a new, stronger type of bioplastic bottle that hit stores recently.

The type of plastic used in the EarthBottles that he and co-inventor David Gangemi developed is also more resistant to heat, which deforms bottles made of 100% corn, he says.

They added some natural ingredients to the mix that retain the biodegradable properties while eliminating the drawbacks, Roberts says. The result is a material that has the potential for use in automotive parts, fabrics and biomedical parts, among other things, he says.

And it's all non-toxic.

"Everything is all food-grade material," he says. "You could grind it up and eat it. It might constipate you, but it wouldn't kill you."

The first company to use EarthBottles is Brevard, N.C.-based Gaia Herbs, a liquid herbal grower and manufacturer that helped finance the Clemson project, Roberts says.

"The original impetus for us was to find a way to save on the cost of freight and the risk of breakage associated with pharmaceutical glass," says Greg Cumberford, vice president of strategic initiatives for the company.

Being a certified organic company, Gaia didn't want to risk any traces of petroleum chemistry mixing with its products by using ordinary plastic bottles, Cumberford says.

EarthBottles also contain natural antioxidants that help protect the product inside, he says.

"The reaction has been overwhelming," says Angela Guerrant, vice president of sales for Gaia who showed the bottles at a trade expo in Boston recently.

"They're shocked that this hasn't been done already."

Barnett is a reporter for The Greenville (S.C.) News.

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