Bioplastics seem to have many benefits, but they aren't the perfect eco-friendly product we might hope for. For one thing, they're more expensive than petrochemical plastics, costing between 20 to 100 percent more [source: Dell]. The industrial processes for making petrochemical plastic have been in place for decades, so the production chain is very efficient. Large-scale bioplastics programs like Coca-Cola's should eventually lead to similar efficiency.
Bioplastics also have problems at both ends of the production cycle. While manufacturing bioplastics may not result in the same fossil fuel emissions as petrochemical plastics, the use of fertilizer and pesticides and conversion of forests to agriculture to manufacture corn or sugar cane counterbalances the benefit [source: Marshall]. Coca-Cola has tried to minimize this impact by relying on Brazilian sugar cane, which is primarily produced on degraded farm lands a long distance from the Amazon rainforest [source: Coca-Cola]. Advances in the use of cellulosic plant products (like corn husks and similar materials) would also reduce the environmental footprint of bioplastics.
Biodegradability and recycling are problems for bioplastics too. It turns out that making consumer plastics biodegradable actually has negative effects on the environment. The first problem is that there are a lot of different types of biodegradability. Some bioplastics biodegrade with oxygen and ultraviolet radiation, so litter left out in the sun will degrade. However, it doesn't completely decompose, the process takes years, and it releases toxic chemicals. Some plastics are designed to biodegrade when composted, and this doesn't do any good if the consumer doesn't compost. Only a few types will compost in a back yard compost bin, in any case. The rest require industrial composting processes. This results in a lot of confusion for consumers. Worse, decomposition of bioplastics releases methane, which is a more harmful greenhouse gas than carbon dioxide.
Worse, it's very difficult to tell bioplastics from regular plastics. If a small amount of PLA plastic is accidentally mixed into PET plastics in the recycling stream, the resulting recycled plastic products will have lesser quality and value [source: PRO Europe]. In other words, you'd have to separate each type of plastic from the other to minimize damage to both plastics. That also means that sticking with recyclable petrochemical plastics, or PET plastics derived in whole or in part from plant-based resources (like Coke's PlantBottle program) results in less pollution and garbage.
There are exceptions – some deployments of bioplastics have focused on closed systems, like university or hospital campuses, where the company that provides the bioplastic packaging also controls the recycling stream. They can recover nearly 100 percent of the bioplastic products and compost or recycle them using the appropriate method for that type of plastic.
If the production chain is streamlined and progress can be made on the use of cellulosic plant material to produce bioplastics, then we could see a significant reduction in the environmental impact of plastic materials. The market for bioplastics is growing slowly but steadily [source: DeRosa], so there's a good chance we'll see serious improvements in the next decade.