Compostable Bags

Shopping trips to Wal-Mart can be quite depressing. Today, however, I was pleasantly surprised. What greeted me as I slinked into the store (other than a creepy old man) were Sun Chips in compostable bags. Intriguing.

After delving into subject, I discovered that the bags are apparently manufactured by a company called NatureWorks, which specializes in creating packaging from corn. The bags start as dextrose (a sugar) derived from corn which is then fermented and becomes lactic acid (the same chemical that causes sore muscles after a workout). The lactic acid is then polymerized, or attached to one another to make a long chain of lactic acid molecules. The polymerized lactic acid can then be used like a plastic (which is also a polymer).

The cost of such a process is apparently now competitive with traditional plastics, and, of course, is more environmentally friendly. Not only are these products compostable, but they do not rely on oil to manufacture.

There are potential problems with this system, however. Corn is a food crop, and as we are experiencing with biofuel, using it for other purposes can drive up food costs. Corn also requires quite a bit of energy and water to grow. With this being said, the technology is simple enough that it can easily be used with some other source of sugar – perhaps a microbe – that will be more energy efficient.

Unfortunately, the Sun Chip bags are not completely made of this lactic acid polymer, but the company assures that they will be as soon as possible. And they are still compostable, though apparently they will not degrade in landfills (at least very quickly). Never-the-less, it is a noble effort and I, for one, encourage people to support it.

Learn more:
• Farrington, D.W.; Lunt, J.; Davies, S; Blackburn, R.S.; “Poly(lactic acid) fibers.” Biodegradable and sustainable fibres. Woodhead Publishing Limited, 2005. Chapter 6.
• http://www.natureworksllc.com/
• http://www.sunchips.com/healthier_planet.shtml