Green Math

While shopping at my local Whole Foods supermarket I noticed a couple of signs that made me go hmmmmmm. I'm sure the typical Whole Foodie type would find the signs unremarkable. They would just glance at them approvingly, letting the words resonate without actually, you know, reading them. As a service to my Liberal readers I though I would post some impressions from a more Republican viewpoint where the resonances of the words don't altogether drown out their meaning. Here's one sign ...


Blurry cell phone photo. Sorry. The sign reads as follows:

The United States goes through 100 billion plastic shopping bags annually. An estimated 12 billion barrels of oil are required to make that many plastic bags.

-- The Wall Street Journal

... and here's the other sign ...


The second sign reads, in part,

U.S. households dispose of of nearly 100 million shopping bags annually. By reducing plastic bag consumption by just two bags a week, you'll throw away at least 100 fewer bags per year.

The first thing to notice is that the number of bags doesn't agree between the two signs. Apparently, the American public "goes through" 100 billion bags a year but only "disposes of" 100 million of them. 999 out of 1000 of them are just stuffed in the bag closet. While it's tempting to believe this -- because it would mean that I am way below average on the clutter factor -- I can't manage it. At least one of the figures is wrong, probably the "100 million bags" part. I know that I throw away a plastic bag more often than once every three years and I suspect my 300 million countrymen do too.

The next thing that struck me is that there are real efficiency gains to be made in the manufacture of plastic bags. If it takes 12 billion barrels of oil to make 100 billion bags then that means that the yield for a barrel of oil is only 8 1/3 bags. With oil at a hundred bucks a barrel that means that the plastic bag you put your organic brown rice into cost $12 to make just for the oil.. On the other hand, if the process could be reversed -- if we could figure out how to get that oil back out of the plastic bags -- then my bulging plastic-bag closet could power a Prius for a trip to Uranus.