Corn-Based Plastic

[Attention: The proper way to dispose of corn-based plastic products is in your green, curbside-pickup compost bin (or a compost heap if you have one in your back yard). If neither of these are options, then put them in a garbage can, rather than recycling bin.]

• In 2007, Americans produced 256 million tons of trash
• 31 million tons of it were plastic
  • Only 2.1 million tons of plastic were able to be recycled; the rest went to landfills

As people are trying to become more green and cut down on their waste, scientists around the world are trying to find ways to cut down on the amount of plastic that goes into landfills. (You may have heard the pseudo-fact that plastic bags take 500 years to decompose.) One promising way to go about this is by developing biodegradable plastics (plastics that break down easily in natural settings -- like a log decomposing in a forest).

What's the problem with the "old" plastic?
The traditional plastics that you and I are used to are developed from fossil fuels (ie oil). This means that there are a great deal of carbon emissions (aka "Greenhouse Gases") from extracting the oil from underground and processing it into plastic. Also, as the oil-based plastic breaks down (over those "500 years" in the landfill), they will continue to release Carbon Dioxide (aka CO₂; aka the main man-made Greenhouse Gas). And this all on top of the space that plastics take up in landfills.

To avoid all these greenhouse gases (and save on rising oil costs), scientists and companies are now developing new types of plastic -- made from things beside oil -- that can biodegrade quickly and without all the Carbon Dioxide. Many different plants are being examined for their potential to be made into plastics (I recently heard about grass-based plastics). In the United States, we grow a crazy amount of corn, and it's rapidly becoming the popular new plastic. (So far, I've especially seen them as disposable utensils and clear, thin cups.)


If it's made from corn, it's "green" right?
The good news about corn-based plastics is that they cause far less Carbon Dioxide to be released into the atmosphere. Heck, the plastic originates from a plant that takes Carbon Dioxide and converts it into Oxygen. (Remember photosynthesis from your Biology class?) Unfortunately, not all of the Carbon Emissions of traditional plastics can be avoided: many of the power plants that run the corn-plastic factories are still burning fossil fuels like coal.

The bad news is that even though this new type of plastic can biodegrade (as opposed to the oil-based plastic), it only does so under very specific circumstances. The temperature must be about 140 degrees, it must be in a Nitrogen-rich environment, and there must be decomposing matter surrounding it. (Burying your corn-plastic fork in the back yard is not enough! You need a compost pile.)

This means that if you toss a corn-plastic fork into a landfill, it will still sit for 500 years next to that oil-plastic bag. And if you try to recycle it, it will just contaminate the oil-plastic that our recycling system is designed for. (The recycling system, of course, can be changed if corn-plastics ever become very common, but it will be expensive and take time.) Fortunately, here in the East Bay, we have an excellent curbside-pickup compost system, in addition to recycling and garbage. That is where the corn-plastic you use needs to be thrown out.

Also, it should be noted that corn-plastics are not as strong as oil-plastics. (As I mentioned above, they are considered a "contaminant" when they mix in with oil-plastics at recycling facilities because they make the oil-plastic weaker.) At cool temperatures, both plastics have about the same strength, but corn-plastic starts to melt at a significantly lower temperature than oil-plastic. This means that on a day where the temperature gets above 100 degrees, leaving corn-plastics out in the sun is a very bad idea. Not only because the plastics become weaker, but because they are toxic to humans and may contaminate any food or water that they come in contact with. (Think about water bottles that sit for a couple hours by the benches at a baseball field.)

Just tell me already: Are corn-based plastics good or bad?
If you have a green curbside-pickup bin or a compost pile in your back yard, then by all means go for the corn-plastics. (If you don't, then the decision can be a little tougher.) I'll say this much: even though they're not perfect yet, alternatives to oil-based plastics are definitely a good thing. Right away, the corn-plastics can reduce the amount of Carbon Dioxide we produce. And in the coming years, we may find plastics developed from other plants that are less toxic as well (oil-plastics are toxic enough as it is).