Paper, plastic, cloth -- or just bag the whole thing? You and the grocer may have different "green" issues

Your local grocers may not be entirely motivated by concern for the environment when they urge you to bring cloth bags to carry home your purchases. It turns out that plastic bags cost nearly two cents each. The useful, versatile paper bags (let me reveal my bias early) cost a nickel each.

These figures were revealed this week in a Wall Street Journal article explaining how Supervalu (the company that runs the Jewel chain here in Chicago) is training its employees to use fewer bags when packing groceries. The WSJ article even had this handy chart showing how things are to be done.

It turns out that those pennies and nickels add up: Since Supervalu initiated these changes in mid-2009, the linked Journal article says, "it has boosted its average items per bag about 5%, saving $4 million to $6 million annually even as prices for plastic bags have climbed."

Baggers at grocery stores have been automatically using plastic instead of paper for some time unless the customer asks quickly (as the Journal article confirms) -- but I'm not sure why.

Both paper and plastic bags can be recycled but, in a landfill, plastic is forever.

According to Wikipedia, plastic bags are "often made from polyethylene, which consists of long chains of ethylene monomers. Ethylene is derived from natural gas and petroleum." Most plastic bags, Wikipedia says, are somehow derived from natural gas, not petroleum. But plastic bags still come from fossil fuels; paper bags come from trees, a renewable resource.

And are plastic bags really cheaper than paper bags? If the customer is taking home only an item or two, the smaller, cheaper bag may be more cost-effective than a paper bag. But many more items can be packed into a paper bag than a typical grocery store plastic bag. So, on larger orders, is there a cost advantage?

Cloth bags make the best economic sense for the grocers, but these only make environmental sense for customers up to a point. Paper bags can be used instead of plastic trash bags in the home for household garbage. Newspapers can be stacked neatly inside of paper bags while they wait for a trip to the recycling bin. Even old plastic bags can have household uses. A lot of people wouldn't be able to walk their dogs without them.

To be as "green" as possible, bring cloth bags to the store -- but not so many that you don't get a few paper (or, I suppose, plastic) bags for household needs.

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Related:'Paper or Plastic' Saving Cash at Jewel, NBC5 Chicago

Will Jewel-Osco's checkout changes leave shoppers holding the bag?, Chicago Sun-Times, March 26, 2011