‘Rubbish mining’ or landfill mining, is being talked of as a new source of energy and valuable industrial materials – Exec investigates if there’s gold in the garbage
Written by Ruari McCallion
Scouring through rubbish tips for reusable items and materials is nothing new. We see the practice on TV regularly, usually accompanied by a serious commentary on how poverty in emerging nations reduces entire families to this means of earning a meagre living. But the rising price of oil has changed perceptions.
“Two years ago, when we founded the company, we could get £60 a tonne for plastic. Yesterday I did a trade with a mill in the Far East and we agreed a price of £250 a tonne,” says Philip Mossop, Development Director at Intelligent Waste Management Systems. “Take packaging. It requires oil to power the machines and to manufacture. A few years ago there was no incentive to recycle plastic – new raw materials were cheaper. Today’s oil cost makes recycling card and plastic more attractive.” The market has grown so much – and so quickly – that there is talk of recycled materials being traded on commodities exchanges.
THE NUMBERS GAME
As with much in business, it’s a numbers game. The important number on this playground is US$100 per barrel. Oil at that price brings remote and expensive resources into the reckoning. At US$100, it becomes worth thinking outside the box and that’s where landfill comes in. We have been a throwaway society since the Second World War; we know that space is at such a premium that permits for landfills will be extremely difficult to gain in the future. It’s estimated that 20 to 30 million tonnes of plastics have been buried over the past 30 years. One challenge is – where is the resource, and what is it?
“We’re very much aware of what went in to landfill – our business came out of landfill activities,” says Peter Mills, of New Earth Solutions. “We have records going back decades. The big landfills have been managed in a cellular manner; we can go from cell to cell, exploiting what is there.” So the exploration costs should be relatively low. While landfill mining, as such, is not happening in the UK at the moment, exploitation of the waste material is already proving to be a valuable activity.
“A landscaped and ‘finished’ landfill site is still active. We’re already tapping some sites for gas,” says Mills. Methane generated by decomposition of organic materials has been viewed as a problem – not any more. It’s a resource. “We’re selling methane for electricity generation – and we get a good rate. Gas recovery is the low-hanging fruit; the technology for capture and sale is all in place and established.” In fact, New Earth wouldn’t seek to mine landfill sites for physical material until the gas resource is no longer viable – and that gives a clue to one of the challenges, which is about management. One doesn’t want the smell of rotting vegetable and animal matter rolling out across the countryside – and not all landfill sites have been as well-managed as many in the UK.
BURIED RESOURCES
Jack Caldwell is a retired but still active civil engineer, based in California. On his website he recounted how he and his team had stripped the soil cover off a large and very old landfill in Los Angeles. Newspapers from the 1950s, fridges and cookers merged, complete and intact. Vapors of toxic chemicals came out so fast that they rushed for gas masks. Oil oozed out and the ashes of past burnt rubbish lay everywhere. One corner of the site kept settling because deep-laid waste was on fire, or, at best, going through ‘expedited thermal degradation’. Open it up and the area would burst into dangerous flames.
We may have buried resources at a time when the technology wasn’t available to recover and reuse them.Now it is – but it isn’t simply a question of digging it all up again and selling them for a fortune. And not everything went into the ground in the first place.
“Metals have been being recycled for years,” Mossop explains. “Plastics don’t biodegrade and they’ve only been there 20 to 30 years. Opponents say the cost/benefit of landfill mining doesn’t work and that there isn’t enough plastic in the ground to make it worthwhile.” And there’s the quality; the polymers in PET and HDPE, the materials used for bottles, is high-quality, doesn’t degrade during re-engineering and is relatively easy to clean and prepare. Older plastics are likely to be useful primarily (if not solely) as fuel for power stations; they have a high calorific value – around 25 megaJoules/tonne. They have captured carbon and the last thing a supposedly green solution should be doing is releasing carbon into the atmosphere.
“Landfills are carbon banks and present an opportunity to us to access and reuse them,” says Mills. “Reuse is more attractive than incineration. We have records; we know how much the manufacturers were producing and where, though we may not know precisely where it’s gone. The advanced technologies for capturing plastic have only emerged within the last decade and it’s still conceptual; the basic engineering principles are sound, it’s about bringing them to market. The challenge now is to attract funding.”
“This has been happening in the Far East for a while but it was when the US began doing it that the UK and Europe pricked up their ears,” says Mossop. Mining will free up void space for continued dumping but it isn’t going to happen immediately – the gas is the more accessible resource and it has to be extracted first.
“My understanding is that landfill owners are investigating this but not trialling, yet. My best guess is it will be at least 12 to 18 months before we see trials. Landfill is a declining asset – once it’s used, that’s it. At the moment, it seems to be the landfill owners who are most interested.”