Greening the Aluminum Can: We Can Do It
Amid the brouhaha about New York City mayor Michael Bloomberg’s proposed ban on the sale of large-size sodas, it’s worthwhile to pause and consider some unintended consequences. Some have commented that they will simply buy two or more smaller sodas to have the equivalent of one large one, defeating the point of the proposed new law — and adding to the amount of waste in the city’s often-filled-to-the-brim trash cans.
While soda cans are often deposited into recycle bins, recycling the cans themselves is not as profitable as it would seem to be as the basic can is made from two types of aluminium, notes the New York Times’s Green blog:
The bottom and sides are made from an aluminum sheet that is strong enough to be stamped into a round shape without tearing. For the top, which must be stiff enough to help the can retain its shape and withstand the bending force when it is opened, can makers blend aluminum with magnesium.
Melting down cans creates a blend of the two types of aluminum that cannot be used for either purpose. Considering that new aluminum sells for almost $2,000 per metric ton, cans that could be recycled and melted down to be reused should be worth about 2.5 cents each (calculating that it takes 75,000 cans to make a metric ton).
As Philip Martens, president and chief executive of Novelis, explains to the Green blog, manufacturers usually mix recycled material with new aluminum, to dilute the magnesium and make the metal usable for can bodies. Alternately, more magnesium can be added to make a stiffer material for can tops.
Novelis notes that it uses 39 percent of recycled materials for its products and that it would like to raise the amount of cans recycled from about 50 percent to 80 percent. There are definite advantages to making cans from recycled aluminum. It takes about one-eighth of the fuel to make a can from aluminum from recycled cans as it does to make one from virgin aluminum.
As the Green blog details, Martens of Novelis is showing a can made from a single metal at a convention of aluminum industry executives:
The trick, he said, is to anneal the metal, treating it with heat so that it becomes strong enough to withstand stamping to become a can body.
“Ultimately you want to get this to be a closed-loop system, where you are working end to end, starting with the consumer and ending with the consumer,’’ he said. A can could come off a supermarket shelf one day and travel to the consumer’s kitchen, the recycling bin, the smelter and then the can manufacturer, returning to the supermarket in 45 to 60 days, he said.
Martens noted that he has been discussing the possibility of a single-metal can with various companies.
Assuming that Bloomberg’s large-size soda ban passes, could calls to “green” the receptacles those smaller-size sodas are served up in be next?
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Photo by brad montgomery