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Mining project hunts treasure in old landfills

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To most people, a landfill is a place where trash goes to stay forever. For advocates of landfill mining, however, a landfill is a temporary storage place for materials that may not be recyclable at the moment. As recycling technology improves, the thinking goes, someday a landfill will be seen as a repository of value, not waste.

While the idea makes some sense, and sporadic landfill mining projects have occurred here and there, no full-scale landfill mining project to strip the value out of a landfill has been demonstrated. But in Belgium, it appears that such a full-scale project may be underway. There, at the Remo Milieubeheer landfill site in Houthalen-Helchteren, a consortium of European firms aim to dig out the tons of contents in the site, convert some to energy and the rest to valuable materials, and then turn the land into a nature park.

According to Group Machiels, the Belgian environmental construction and development company that owns the site and is spearheading the effort, it will take 20 years and more than $280 million dollars to complete. Machiels said the site contains more than 16 million tons of waste, of which 45 percent can be recycled as material. The balance will be converted to energy through a gas plasmafication process supplied by its partner, Advanced Plasma Power of London.

An energy plant using up to five of Advanced Plasma Power’s Gasplasma units will be constructed, generating up to 100 megawatts of electricity, enough to power 100,000 homes. The vitrified residue from the Gasplasma plants will be marketed as construction material.

Technology Arrives

One of the key elements of the Remo project is the availability of Advanced Plasma Power’s energy conversion technology. “This process delivers high overall energy efficiency, maximum combined heat and power potential, maximum landfill diversion, minimal generation of secondary residues and very low plant emissions,” said Advanced Plasma Power CEO Rolf Stein.

Stein said valuable recyclable materials will be filtered out at the beginning of the process. The remainder – largely organic material – will be processed into energy. The company describes the Gasplasma process as consisting of three stages. In the first, waste feedstock is gasified to produce ash and gas. A plasma converter removes impurities in the gas and vitrifies ash and inorganic fraction. Finally, the cleaned gas powers gas engines to generate heat and power.

Landfill mining’s past

The first landfill mining project dates back to 1953, when a project in Israel removed soil for spreading on agricultural fields. Its record since has been spotty, with a few projects in the U.S., mostly devoted to recovering landfill space and creating energy. Beginning about 10 years ago, landfill mining began attracting attention again. However, a number of significant obstacles have kept landfill mining from taking off.

The technology is a primary issue. While landfill contents may contain concentrations of valuables such as gold and aluminum that are richer than many ores, the technology to effectively recover these materials in the environment of a landfill has been lacking. Machiels said it has addressed these challenges, although the company hasn’t said exactly how.

Financing has also been difficult to obtain, owing to the uncertainty and long time frames involved. The Belgian project is relying on government renewable energy credits for much of its financial support. Other issues include social acceptance of using recycled materials for construction and other purposes, and conforming to regulations that make working in the often-toxic environment of a landfill challenging.

Landfills make difficult mining sites in part because there is little information about what is stored in them and where it is. Sites are typically unstable for decades after closure, and contaminated with dangerous gas and leachates. The mixed contents require separation and cleaning before processing, which takes energy and costs money.

Social pressures also act against the concept. Many old landfills are in urban areas or close to recreational areas. Some have been closed and turned into parks or other uses. Turning such a site into a vast industrial project with lots of trucks and heavy machinery often faces opposition.

The practice of taking revenue-producing methane from many sites is also an obstacle, because landfill owners don’t want to give up certain methane revenue for the uncertain promise of mining profits.

Finally, the cost of such projects is significant. From selecting a suitable site from the short list of acceptable candidates, to re-landfilling waste that can’t be used, the capital and operating costs of landfill mining are enormous. The fact that one joint project has actually taken steps to mine a large landfill on an industrial scale has, therefore, considerable significance for landfill operators and recyclers. What works in Remo may work elsewhere, and that could change the picture profoundly.

Group Machiels has been researching landfill mining since 2006, and has collected approximately 2,500 tons of material for testing. Among the questions investigated was how much different landfill contents had decomposed since it first began being used in the 1960s. Now, Machiels has set a date of 2014 for when the project will become fully operational. Whether that happens or not, the company reported receiving inquiries from many nations seeking information that might help with other landfill mining projects.

At this point, all Machiels can point to are its studies and pilot projects suggesting that landfill mining could work. Otherwise, landfills today remain what they have always been – final resting places for materials nobody could find any use for. Depending on what happens at Remo – and how lawmakers, regulators and financiers react to it – that could change.

“There is clearly potential for the extension of landfill mining to countries all over the world,” said Advanced Plasma Power’s Stein. “Rising land values in many cases provide an additional incentive to clear land for development. It will not happen, however, without a supportive legislative and regulatory framework.”