Kernels of Hope for Bioplastics

There’s some encouraging news for polylactic acid, the promising but beleaguered corn-based polymer intended to replace conventional petroleum-based plastics and help usher in a new era of biobased products.

Corn-based plastics have been around since the 1930s, when Wallace Carothers, a scientist for Dupont, produced a low molecular weight product by heating lactic acid under a vacuum. But they became the darlings of what some have come to call the carbohydrate economy in the 1980s when Cargill, one of world’s largest food companies, began to develop polylactic acid polymers. In 1997, Cargill formed a joint venture with Dow Chemical Co. to Cargill Dow Polymers. Together they built a large-scale $300 million PLA manufacturing facility in Blair, Nebraska, about 20 miles north of Omaha.

But sales of PLA plastics have been slow to take off. In June, Dow announced it was pulling out of the joint venture, cutting its losses at about $750 million. Cargill rechristened the company as NatureWorks, reflecting the brand name of its flagship PLA product. Sales are growing, but the plant is operating well below capacity.

The problems have been largely economic. In a world in which plastic remains largely a commodity, NatureWorks is a more costly alternative for its principal uses: for packaging material, from plastic bottles to film wrap, and for fibers used in pillows, comforters, and apparel.

Another challenge for PLA are genetically modified organisms, or GMOs. Because about 30% of the U.S. corn supply is genetically modified, some potential PLA customers -- progressive food and apparel companies, for example -- have been reluctant to have their PLA-based products tarred by the “Frankenfoods” brush. (It should be noted that no GMO corn molecules actually end up in PLA material; it dies off during the fermentation process. But many activists believe that supporting PLA means supporting conventional corn production.)

Still another challenge is that part of PLA’s promise -- its biodegradability -- has been stymied by the relative lack of composting programs in the United States.

Things have looked bleak. Environmentalists and entrepreneurs agree that if Cargill can’t make a go of bioplastics with all of its hundreds of millions invested, probably no one can, either. And if NatureWorks goes belly-up, it will be a long time before investors pony up for another bioplastics plant.

But two recent developments are encouraging. Earlier this month, DuPont and Tate & Lyle announced that they plan to open a new $100 million plant in Tennessee that uses biobased resources to make high-performance products. Scientists from the two companies have developed a new method to use corn to produce 1,3 propanediol (PDO). The resulting product, Bio-PDO, is a key ingredient in the production of DuPont Sorona, a DuPont polymer used for clothing, carpeting, plastics, and other products.

Producing Bio-PDO consumes 30-40% less energy per pound than petroleum-based PDO. Production of 100 million pounds of Bio-PDO will save the equivalent of 10 million gallons of gasoline per year, say the companies. The U.S Environmental Protection Agency presented DuPont with its annual Presidential Green Chemistry Award in 2003 for the company's research leading to the development of the Bio-PDO process.

Meanwhile, NatureWorks recently announced plans to launch a large-volume “buy-back” program in North America for post-consumer bottles made from PLA.

Through the buy-back program, commercial municipal recycling facilities in select geographic areas will separate post-consumer PLA bottles into bales, which NatureWorks will buy. The company will take them “to an appropriate end-of-life solution and/or post-consumer use based on geography of collection and prevailing market economics,” it says. PLA can be sorted from other plastics using standard near-infrared equipment.

NatureWorks says it hopes the program will help create a bridge to the development of a commercially viable post-consumer PLA market -- and that can only result in increased market acceptance for PLA itself.

Comments

[Mitra Ardron]

I think you've hit the mark here - PLA is more expensive, so it only really appeals to companies with a social conscience. But most of my clients don't want to switch to PLA if it means supporting GMO agriculture (I agree with you that there is no GMO in the plastic, but its certainly encouraging GMO growing to have a ready market for more corn).

If NatureWorks is serious about tackling the socially responsible market then it seems to me that they need to offer a GMO free product before PLA gets such a bad name that its hard for them to counter it later.

- Mitra Ardron

[Rob Nathan]

I know I am commenting on a blog posting from a long time ago, but your feedback (and your readers') would be appreciated.

I am an industrial designer and I have been working on PLA packaging at the company for which I work, Edge Ideas. Our main brand is SOLE Custom Footbeds (http://www.yoursole.com).

We have changed our PET packaging to PLA packaging. Originally we had made the packaging out of paperboard but it was not durable enough. We are actually one of a very small group of manufacturers to produce PLA packaging for a non-food-related product.

But we are now rethinking the change. The big question is, "What is the most environmentally sustainable packaging material?" PET, PLA, or would paper or a different biopolymer be even better? Perhaps Metabolix's Mirel biopolymer? The EU is working on Sustainpack to figure out a total packaging solution, but results of this are years away. What about right now?

• We have had to add 5% or so strength modifiers to the PLA so that it is durable enough for our application. Adding the strength modifiers means that the package is no longer certifiably compostable. Since it is not compostable, it will all end up in landfills, where the vast majority of PET ends up as well, regardless of recycling efforts. There are no PLA recycling projects yet.
• PLA still uses less energy than a comparable PET package.
• PLA produces less carbon dioxide and uses slightly less water than PET.
• PLA uses less petroleum since there is none used in the actual packaging, though it still uses petroleum-based fertilizer to grow the corn, to drive the tractors, etc.
• By using PLA some think that we are supporting GM corn, which comes with its own set of environmental and health concerns. NatureWorks has an offset program that I just found out about and that we will hopefully begin to use. They track every ounce of resin that a company uses, translate it into bushels of corn that would be needed and will then buy that amount of conventionally grown corn. Therefore, our PLA may not have been made entirely from non-GM corn, but the amount of corn we are using is at least going into the stream of PLA and someone will be using it. This is the same as green power offset programs using wind power and the like. If Natureworks’ customers in North America asked for PLA from non-GM corn, like their European customers already do, then NatureWorks would only buy non-GM corn.

Is there a "best" material, or is this a question of doing what may be the best for now, as we wait for a full packaging system to be developed, that is more sustainable from cradle to grave?

What do you think of the question? Any input would be greatly appreciated.

Thank you,
Rob Nathan

[Carl Zamecnik]

My company makes food packaging from PET and Polypro. We had looked at PLA for several projects, but were hesitant to put out a product that softened at 114F, and needed to be shipped to customers in refrigerated trucks, and stored in climate controlled conditions. Pretty expensive. However no one counts the added energy required for that kind of handling. In addition, there's the biodegrading aspect we looked at, and were pretty shocked. The plastic doesn't biodegrade in landfills, in seawater, or in compost situations at home. If you read their claims carefully, they only degrade in "commercially managed" compost facilities that generate sustained heat of 140F, of which there are about 100 in the country, and only 25% of those take municipal waste. That means only a tiny fraction of that material will ever biodegrade the way they claim. In fact it has the same 100-1000 year life as regular plastic when landfilled. So where's the green?
We have been involved in a different approach that we are bringing to market, and that is Bio-PET. It is actually APET material with a proprietary addative that allows the plastic to biodegrade in landfills, composting (even backyard style), in seawater, in sewage sludge, and of course the "commercially managed" compost facilities. While this is conventionally made PET material produced from petroleum, we feel that it's afterlife is the real impact on the planet. We like the fact that this Bio-PET will completely degrade in 6 months to 5 years depending on bioactivity of it's environment. That sure is better than 100 to 1000 years. Plus, in landfills, it anaerobically degrades to produce methane. This methane is now an important resource at landfills, and is siphoned off and sold to heat homes, and even make ethanol.
And the impact on petroleum? Walmart is changing 114 million packages to PLA material, saving they say an estimated 800,000 gallons of gas. The U.S. used 138 BILLION gallons of gas in 2006. Saving 800,000 gallons amounts to about 5 ten thousandths of ONE percent savings. That's the biggest retailer in the world making a huge volume commitment to PLA usage, and the savings in petroleum is way too small to even see. I think the waste problem is the most pressing one here, and our Bio-PET seems to be a good answer for now. Check us out at www.candlamerica.com.