Compostable plastic bag? For reals?

So I was at the supermarket this weekend and I saw, proudly displayed, the new Sun Chips, 100% compostable plastic bags. The warning on it says that the downside is that it makes a loud rustling noise. Well, I can live with that. But, is that really the only caveat?

Remember the supposedly biodegradable plastic bags? Tests proved that they never degraded all the way. All they did was break the plastic down into small pieces that were more likely to seep into ground water. Not so great.

So I surfed the Net a little about the new Sun Chips bags (They have an awesome video of the bag decomposing here). And here's the good and bad news.

• The chips are delicious (you know they are!).
• The bag is fully compostable and breaks down completely in 14 weeks, but
• Only the outer layer of the plastic bag is compostable. There's an inner layer and some glue in between that are not compostable (The Web site doesn't explain how you separate the two, but I'll assume they made it easy), and
• The outer layer only decomposes in a compost pile that contains oxygene and water, not the anaerobic (dry and airless) conditions of a landfill, and
• Finally, the Web page Sustainable Business says the bags cannot be composted in the average household compost bin and only break down under the hot conditions created by large commercial composting operations. The catch-22 is that "many commercial operations do not accept compostable plastics, because they do not match the shorter composting cycles for yard waste, food waste and other typical organic materials."

Still, it's a good first step.