Kamis, 15 September 2011

Food-based Plastics A Good Idea?

Once upon a time, food was used for one thing: eating. Today, it has a much more complicated role; scientists, manufacturers and policy makers are exploring whether food could one day eliminate our dependence on oil. Food-based fuels like ethanol and biodiesel are increasingly replacing gasoline and diesel in our fuel tanks. Now, some think food can do the same thing to the plastics industry, helping to replace more than 900,000 barrels of oil and natural gas used to manufacture plastic in the United States daily [source: U.S. EIA].
Food-based plastics, made out of everything from corn to sugarcane, have rapidly grown in popularity over the past several years. Packaging materials, gift cards, cell phone casings -- all can be made from these eco-friendly materials. As the quality of food-based plastics improves, they will have broader and broader applications.

Proponents cite two main advantages of food-based plastics over their petroleum-based counterparts. First, they're made from a renewable resource. As long as farmers grow the crops these plastics are made out of, production can continue indefinitely. Second, food-based plastics are widely considered to be easier on the environment. For instance, they require much less energy to produce than traditional plastics and release fewer greenhouse gases in the process. Better yet, they break down into harmless organic compounds -- in the right conditions.

Now for the drawbacks. One of the most glaring is their relatively low melting point. While popular plastics like polyethylene terephthalate (PET) may have melting points well beyond 400 degrees Fahrenheit (204 degrees Celsius), some plant-based plastics turn into puddles just from being left in a car on a sunny day [source: Machinist Materials]. For instance, polylactic acid (PLA), a corn-based plastic used by retail giant Wal-Mart among other companies, can have a melting point of just 114 degrees Fahrenheit (46 degrees Celsius) [source: Royte]. As a result, food-based plastics are simply unsuitable for a wide range of applications.
What's more, food-based plastics may not be as environmentally friendly as they appear. While they are biodegradable, most only break down under very specific conditions found in industrial composting plants. That means you can't simply throw them on the compost pile in your backyard and expect them to turn into soil, and if they do end up in a landfill, they break down just as slowly as conventional plastics.

While food-based plastics can be recycled, they can't simply be mixed in with other recyclable plastics. In fact, the recycling industry considers food-based plastics a "contaminant" that takes time and money to process.

A final argument against food-based plastics is that generating them requires land and resources that could be going to producing actual food. Already, the U.S. Department of Agriculture (USDA) estimates that, by 2014, nearly a quarter of all grain production will go toward making ethanol and other biofuels; if food-based plastics take off, that number could climb even higher [source: Baker and Zahniser]. Environmentalists also worry about the harmful effects of the pesticides and genetically modified crop strains used to create some of these plastics.

But don't give up on food-based plastics yet. While they still represent less than 1 percent of the plastics market, some very large companies have committed to both improving and using the plastics moving forward [source: Environmental Leader]. 

For instance, electronics manufacturers Panasonic and NEC have both announced the development of food-based plastics with significantly improved durability, heat resistance and ease of production compared to products currently on the market. Metabolix, another bioplastics manufacturer, has developed a plastic called Mirel that biodegrades in normal compost piles. 

Production costs for food-based plastics are rapidly dropping as well, which, coupled with their widening range of applications, will make them a much stronger alternative to conventional plastics moving forward. Perhaps the strongest argument for food-based plastics, however, is that after we've finally exhausted our supply of oil, they'll still be waiting for us.

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 by "environment clean generations"

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