I believe that introduction of biodegradable plastic should be done in a reasonable way which can demonstrate benefit to the environment. If not, the Boom could turn into a Fiasco such as with bioethanol. Bioplastic has a "great potential", but it is "vital" to introduce them with the suitable infrastructure so they could be properly disposed of.
- The recycling facilities where they are likely to contaminate the waste stream. For example in Quebec, recyclers have problems with oxo-biodegradable bags which degrade the quality of the recycled products. Recently they encourage people not to put these bags in the recyclable plastics bin).
- Landfill where they will increase the generation and release of methane, a greenhouse gas 23 times more powerful than carbon dioxide.
- Petroleum and fertilizer are used in the growth and production processes, specifically in corn-based PLA made by Cargill's Natureworks - this is by far the most well-known material which is shaped into disposables
- Using disposables doesn't change our approach to consumption - one use, throw it out.
- PLA which is clear actually "contaminates" the recycling stream as it dilutes the quality of plastics once they are melted, requiring yet more additives to make it usable to constitute new products.
Another approach might be to use bioresins developed from non-food vegetable oil (e.g., Jatropha) which do not require the use of fertilizer or petroleum in the growth and production processes.
Rob is correct in that if bioresins begin to be used throughout society initially, it would contaminate the recycling stream. On the other hand, there are high volume users (e.g., catering, cafeteria systems, etc.) that control their own waste stream - thereby eliminating the possible contamination. In addition there are many other possible non-disposable uses of bioresins (e.g., everywhere plastics are typically used in our home and factory used).
In my opinion, biodegradable plastics are not part of a sustainable future.
If your target is sustainability, the key is to reduce or eliminate the waste. In Ontario we have been recycling for 20 years and while recycling is better than adding to the land fill, it is best to reduce the packaging we use. The new term for this is PRECYCLE, which refers to fixing the problem at the source. Precycle is the practice of eliminating the waste from the start so there isn't a by-product that has to be recycled... i.e., fix the problem at the source instead of fixing the symptom/by-product.
The biggest concern with bio-plastics is the "monstrous hybrid" dilemma, a term coined by Cradle to Cradle authors Michael Braungart and William McDonough. When we blend natural with synthetic we create monstrous hybrids. The natural can't be broken down and the synthetic can't be recycled. We thereby lose all positive/sustainability traction. It can't be recycled or composted and must be thrown away.
The bioplastic discussion with respect to sustainability has to include talking about the systems in which it will be created, utilized, and ultimately disposed of. The PreCycle that Scott Bennett talks about is a part of this process. As with all new products and inventions we need to ask ourselves "Just because we can make it, should we make it in the first place?"
Bioplastics do less bad which simply kicks the can down the road for awhile.