One energy-from-garbage proposal that is plasma gasification, which produces synthetic gas that can be used to generate electricity and a byproduct that can be used as aggregate in road construction. Landfill mining takes it a step further, aiming to screen the garbage for recyclables before producing syngas
It seems there have always been people in Third World countries who are forced to eke out a living of sorts by scavenging in city garbage dumps for something — anything—they can sell for a few pennies so they can buy a bit of food.
Now, though, we’re hearing about picking through garbage in an organized manner to find commodities of value in an organized salvage market.
It’s being called landfill mining, and we’ve been hearing about it for some time — but always as something a decade in the future.
We’ve long since had organized recycling of consumer electronics, where various metals and other substances are saved and resold. That’s why the old computer monitor you just replaced has value as scrap.
But in the days before recycling, a lot of stuff went to the dump that has value today, so some folks think there is money to be made in mining that old trash. It’s been a hard sell, though, until just lately, when people began thinking seriously of generating energy from garbage. The two ideas might make a good fit.
Energy-from-garbage proposals take different forms, but one that is causing some excitement in the industry is plasma gasification — a means of destroying garbage in extreme heat in a closed vessel that excludes oxygen.
The result is a synthetic gas, or syngas, which can then be burned to generate electricity. The byproduct is often an inert, glass-like substance that can be ground for use as aggregate by roadbuilders.
Half a dozen outfits, like Plasco Energy, in Ottawa, have been working on the idea, and Plasco has had a pilot project running (with occasional glitches) at a landfill in the city’s west end. They are also aiming to build a plant in Red Deer, Alta., and at locations in the United States, China, and, perhaps, Poland.
But Plasco just takes garbage as it’s delivered to the dump. After sorting through it for recyclables, it goes into the furnace.
Landfill mining is more than that. It means digging up old landfills and screening the garbage for recyclables. These would be present in larger quantities than in new garbage, because the garbage is from an era before recycling became popular.
A British firm called Advanced Plasma Power, has signed a deal to dig up a giant landfill in Belgium. It reckons it can recycle half the rubbish and use the rest to produce syngas using plasma gasification.
Plasma gasification is a generic term, and while different firms might offer different descriptions, the process is fundamentally the same, no matter which company is promoting it.
The Belgian project is scheduled to go into operation in 2014, and is thought to be the first of its kind in the world. The 30-year project will reuse 16.5 million tonnes of municipal waste dumped since the 1960s. The syngas created will fuel a 60-megawatt plant capable of supplying about 60,000 homes.
It’s being watched carefully because of the need to free up landfill space, and because of the value of recycled metals which can be recovered, has risen sharply in the last couple of years.
Toronto trucks a lot of its garbage to landfills in Michigan. Ottawa trucks some of its waste to upper New York State. That’s ludicrous in an era when we should be trying to reduce carbon dioxide emissions that arise from vehicle use.
Every city of any size has an old landfill or two sitting idle, and it now seems they might be mined profitably.
When city and provincial governments finance more research into plasma gasification, and begin actively to promote its use, we could end up with clean, renewable electricity, more room in our old landfills, and fewer trucks on the road.
Korky Koroluk is an Ottawa-based freelance writer. Send comments to firstname.lastname@example.org