April 2008
The value of the materials contained in landfills makes mining a solid idea in many settings, but not all.

High commodity prices boost landfill mining prospects
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Landfills contain tons of commodities that could be recovered. While much of the technology needed for mining landfills is already proven, the process is not yet economically feasible. But thanks to record commodity prices this may soon change.

“At some point the land upon which landfills are located will become too valuable to leave as landfills. The materials in the landfills - especially aluminum, copper and some plastics - will become valuable enough to make the mining, recycling and land rehabilitation processes attractive,” said Patrick Atkins, president of Atkins 360 LLC in Pittsburgh and an advisor for Pegasus Capital Advisors, a private equity fund.

Before joining Pegasus as an environmental consultant last year, Atkins was the director of energy innovation at Alcoa, Inc., the Pittsburgh-based aluminum producer. He was responsible for identifying and supporting alternate energy sources for Alcoa.

A handful of states investigated the feasibility of mining landfills last decade. But the idea has basically been dormant since then. Atkins said no one is currently working on landfill mining on a commercial scale. But with prices of many commodities hitting new records he thinks this might change. “This is an idea that requires careful economic review, and will not work in all cases, but it could be a winner in many settings,” he said.

The lack of technology is not the problem. There are already economical processes to re-melt aluminum for example. There are also processes used to separate aluminum from solid waste before incineration, such as an eddy current magnet that deflects aluminum from a flowing stream of material. But Atkins said the two processes have not yet been put together to separate aluminum from mined landfill material.

Atkins estimates that aluminum is about one quarter of one percent of the material by weight in municipal landfills. Each year in the United States about half of the 100 billion aluminum cans used are lost to landfills, he said. At 30 cans per pound that amounts to 1.5 billion pounds of aluminum in landfills.

“At $1.25 per pound of aluminum, the value is significant,” Atkins said.

Atkins’ former employer, Alcoa, is not interested in mining landfills for aluminum at the moment. Kevin Lowery, a spokesman, said Alcoa has instead invested significantly to expand its recycling capability and capacity. “The biggest opportunity – and the more efficient one – would be to get the material before it goes to a landfill,” Lowery said.

It is not only aluminum, however. There is steel, copper, plastics and other materials of considerable value in landfills. Plus the land itself, usually near or in cities, is of considerable value, Atkins said. Plus, many landfills are being tapped to collect the methane gas that is being generated as anaerobic bacteria degrade the organic material.

“This process of converting the organic components could also be accelerated by the mining process, using controlled reactors to produce the gas rather than relying on the more open, natural processes, which result in lower British thermal units,” Atkins said.

Reid Lifset, associate director of the Industrial Environmental Management Program at Yale University has done research on landfill mining. His research focused on copper in landfills. He said that the economics behind the process are not yet favorable.

“Most efforts at landfill mining reflect circumstances specific to a particular location or facility,” Lifset said. For example there may be need for fuel to fulfill a put-or-pay contract at a waste-to-energy plant or a need to delay a landfill closure.

“Our research told us that with current technology and prices, landfill mining is generally not economically viable - the benefits such as revenue from sale of recovered metals, reduction in regulatory costs, generally did not outweigh the costs,” he said.

Copper mines are extremely large enterprises allowing for the use of gigantic equipment that results in economies of scale. “Landfills, especially older ones, tend to be much smaller,” he said. “The copper in landfills, while large in aggregate, is widely dispersed across many locations, making it harder to realize similar economies of scale.”

Because costs would often outweigh benefits, Lifset said that landfill mining on a commercial scale would probably not catch on in the near future. “We have not ruled out the mining of landfills. But we do not see it as likely in the near term,” Lifset said.

Higher tipping fees might make the process more economical, however. Or higher costs for landfill closures might help. Also, if the prices for secondary materials increase further, it might make landfill mining more feasible, Lifset said. “The single largest thing that could enhance landfill mining would be a breakthrough in the cost of processing.”

Lifset said his research found that landfill mining is not typically motivated by materials recovery in the traditional sense. Instead, landfill mining is often motivated by more than one goal. Projects would therefore be more viable if they accomplish more than one thing – for example, recovery of metals, provide fuel for a waste-to-energy facility, postpone a landfill closure and remediate landfills with environmental problems.

“Most projects will only find a small subset of these benefits to be relevant,” Lifset said.