Are Biodegradable Plastics Good for the Environment?

Solutions for a Throwaway Society
By Anna Burroughs

Takeaways

Non-petroleum based plastics offer biodegradable alternatives for packaging and food containers.
These plastics are made from natural starches found in a variety of foods including corn & potatoes.
Using these plastics have the potential to reduce pollution and petroleum reliance.
Conventional petroleum based plastics make up 25% of landfills in the United States. The production of these plastics requires 200,000 barrels of oil per day. Most of the plastic products are used for packaging and containers for food transport and sale. An alternative to conventional plastics is available through a resin known as polylactic acid (PLA) or corn-plastic.

The largest producer of PLA resins is Nature Works located in Blair, Nebraska. Nature Works is owned by Cargill, the largest corn merchant in the world, so Nature Works’ PLA resin comes from corn. At the factory, corn kernels are milled and dextrose is extracted. The dextrose is fermented and lactic acid is produced as a by-product. Lactic acid can be derived from other starchy sources, such as potatoes, but Nature Works relationship to Cargill makes corn the logical choice. Nature Works converts the lactic acid to lactide and then links the lactide into long chains known as polymers. These polymers are polylactic acid or PLA.

At Nature Works, the final product is PLA resin in small translucent pellets. The pellets can be melted and shaped into containers that can be used to transport and sell food but avoid the land fills because they are biodegradable. Unlike the more common petroleum based plastic polyethylene terephthatlate (PET), PLA plastics can be composted meaning it will break down into natural compounds.

Not only does PLA have the potential to reduce waste, unlike its predecessor PET, PLA is made from renewable resources. It also requires 65% less energy to produce. It produces 68% less greenhouse gases and contains no toxins. These statistics translate into a more efficient and less expensive product. The world’s biggest bottom line watcher, Wal-Mart, uses PLA for two reasons: it’s biodegradable and it costs less. Wild Oats Natural Food Stores switched to PLA containers in their deli department and saw a positive consumer reaction that increased the department’s sales. The well known line of organic foods Newman’s Own also switched to PLA containers where possible because, as its CEO Peter Meehan noted, “no one has ever gone to war over corn.”

It costs Nature Works $1 to produce 1 pound of PLA. Even if it is used just once, the PLA product will decompose into carbon dioxide and water in 90 days in an industrial hot compost environment. There are about 100 such facilities nationwide but not all accept municipal compost material. The waste management industry will have to adjust its methods of collection and disposal as PLA becomes more prevalent.

While biodegradable, the PLA does alter compost environments increasing both moisture and acid levels. This decreases the oxygen available to the microbes which make compost happen. However, many waste management facilities are aware of the pending changes that a higher volume of PLA would bring. In anticipation, some facilities plan to convert to anaerobic compost processes, a method that doesn’t require oxygen.
Some stores, such as Wild Oats, that sell products made with PLA currently accept responsibility for recycling the products. Others, like Wal-Mart, do not. So what can consumers do with a biodegradable product that they can’t compost themselves? The waste management industry worries that PLA products have the potential to wreak havoc. PLA and PET products appear similar but must be handled in two completely different ways. PET products, like soda bottles and milk jugs, are handled by processors which break down the plastics and make them into new products. At current, waste facilities have an increased cost to separate PLA out of PET bundles. Nature Works has suggested that waste management facilities separate the PLA and sell it back to Nature Works but the cost is still fairly high to the recycling facilities.

The concern with PLA is that it will end up in landfills alongside PET products all of which will remain for at least a hundred years, maybe ten times as long. The other criticism of PLA is that it uses a resource that is scarce in many parts of the world, including the United States: food. Already, much of the US agricultural harvests are converted to non food products and the question remains do we want this to increase when so many people are hungry? Also, monoculture cultivation of corn is not an environmentally friendly practice. It is the most chemical dependent crop in the US, a title that includes an assortment of other environmental downfalls including contributing to soil erosion and water pollution.

Proponents of PLA tout its immediate benefits: its lower production costs, biodegradable potential and use of renewable resources instead of petroleum. Ecologists argue the need to produce goods that are aligned with natural processes and can be cycled back into these processes. The overwhelming consensus is that widespread consumer habits won’t change as fast as the environment requires and that adapting products to existing behaviors is the best way to “change from within.” Challengers of PLA offer this question: Why are we using so much plastic at all? Like many environmental issues, increasing PLA use poses more questions whose outcomes are difficult to predict. However, between the current given choices, PLA is the lesser of plastic evils.

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