Matthew Ryan Williams for The New York Times

Of all the materials that are commonly dropped in recycling bins, aluminum is by far the most valuable. New aluminum sells for almost $2,000 a metric ton, so recycling old cans would seem to be profitable. It takes about 75,000 cans to make a metric ton, so each one should be worth about 2.5 cents.

But recycling the cans turns out to be harder than it looks, because the basic soft drink or beer can is actually made of two kinds of aluminum. 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.

When the two parts of the can are melted down, the result is a blend that is suitable for neither purpose, according to Philip Martens, president and chief executive of Novelis, the largest American supplier of aluminum sheet. The solution today, he said, is to mix the recycled material with new aluminum to dilute the magnesium concentration and reduce the metal’s stiffness so it can be used for the can bodies. Or, more magnesium can be added so the material can be used for can tops. Last year Novelis used recycled aluminum for 39 percent of its input material.

Nationally, about 50 percent of aluminum cans are recycled. But Novelis would like to raise that to 80 percent by 2020.

One big reason for setting that goal is that making a can from virgin aluminum requires enough fuel to make 3.5 kilowatt-hours of electricity, which amounts to three to four hours of average household use. Using recycled cans brings the energy requirement down to about one-eighth of that. So raising the proportion of recycled material is environmentally advantageous. But to reach that 80 percent goal, Novelis will have to find a way around the alloy problem.



This week, at a convention of aluminum industry executives organized by American Metal Market, a source of news and data about metals, Mr. Martens will be showing off a can made from a single alloy. 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.

The changes in the can would have to be invisible to the consumer and be fairly cheap; the beverage business is quite competitive. But the can with the higher recycled content could be “a differentiator” that would boost supermarket sales, Mr. Martens said.

“We do believe in the issue of business sustainability,” and producing a material “where the consumer will say, ‘Why not?’ ” he said. He said he was in discussions with several companies that buy his aluminum and make the cans.