We’re all familiar with the two main arguments for PLA and other bioplastics: They use renewable sources, and they’re compostable. But I recently came across one I never heard before: Corn-based polymers could be a way to sequester carbon emissions.

The idea of liquefying CO2 and storing it underground (or under the ocean) has been kicked around for years, but has never been deemed practical. According to this twist, landfilling containers, film, etc. made from PLA would be a form of carbon sequestration. The thinking is: Carbon dioxide is absorbed by corn, which is made into PLA, which is landfilled. QED, the CO2 that the corn absorbs is sequestered.

I can see some problems here: 1) This process would bypass composting, which is supposed to be what makes bioplastics green in the first place, and 2) there’s a strained, Rube Goldbergesque quality to the whole scenario.

On the other hand, composting PLA is problematic in any circumstances. As for the logic or lack thereof, let’s just say that a lot of ecological arguments and strategies involve faith just as much as logic.

This article has a good discussion of the issue. (The sequestration aspect comes in at the end.)