Stories tagged landfill

Is that a contradiction in terms?

Approximately 330 million tons of garbage filled landfills in the United States last year alone, according to Solid Waste Digest, a trade publication for the waste industry. However, remarkably, the capacity of these landfills has been increasing even though very few new dumps are being built. How is this possible?

It turns out that landfill managers have been using methods that allow them to pack more trash into a landfill then what was previously thought possible. Some landfills pile tons of dirt on top of sections of their dumps and then six months later scrape the dirt aside. Like stomping your foot into the waste bin to make more room, this system works to create 30 to 40 more feet of depth — more space for more trash.

Other methods to increase landfill capacity include blowing water and air into the dumps to quicken decomposition and therefore reducing the size of buried garbage. Or, they are using other methods, such as giant 59-ton compacting machines, to bury trash more tightly.

The good news here is that this efficiency will help to reduce the need for new landfills. The bad news is, again, the United States produces 330 million tons of garbage a year! New York City produces so much garbage that it exports 25,000 tons of trash every day to other states and other cities.

So, while I think this new efficiency is great, I also think that we (you and I) still play a significant role in reducing the amount of trash put into landfills. Reduce, reuse, recycle!

Tags : trash, dumps, waste, landfill, efficiency

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With all the doom-and-gloom stories in the news about how we might soon run out of space in landfills and fossil fuels, it's nice to read about an innovation that uses landfills to provide energy.

Methane forms when organic waste decomposes in the absence of oxygen, as in landfills. At a few landfills, the methane is collected and used to power vehicles or to heat nearby buildings. But most of it goes to waste. Landfill operators burn it off to prevent dangerous build-ups of the flammable gas. Burning off the methane not only wastes the potential fuel, but it also pumps pollutants into the atmosphere. In Europe alone, landfills have the potential to generate as much as 94 billion cubic meters of methane per year.

Why don't we use the methane from more landfills? Well, people usually extract it by sinking pipes into the landfill and sucking the gas out. But if the landfill isn't airtight, sucking out the methane also sucks in air. The oxygen is not only difficult to separate from the methane, but it also slows down methane production inside the landfill. So, until now, the only landfills where methane extraction has been viable have been those large and deep enough to restrict the entry of air.

But Viktor Popov, at the Wessex Institute of Technology, has figured out some simple modifications that allow methane extraction from any landfill. His solution is to cover the landfill with a membrane that prevents air from getting in. The membrane consists of three layers: a middle, permeable layer sandwiched between two mostly impermeable layers. Popov continuously pumps carbon dioxide (which can itself be extracted from the gasses in the landfill) into the middle layer so that the CO2 is slightly above atmospheric pressure. This creates a barrier that prevents air being drawn into the landfill—as the methane is sucked out of the ground, CO2 gets sucked into it from the membrane.

You can see a diagram of how this works

A landfill can continue to be a source of energy long after it's closed to new garbage. Decomposition can keep going underground, producing methane, for 15 to 20 years.

Are you interested in new sources of energy? Would you be willing to pay more for "green energy" if the option were available to you?

Tags : energy, methane, fuel, trash, landfill, innovation, out of date

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