Saturday, January 21, 2012

Hot Plasma Makes Quick Work of Garbage -- And Generates Power Too!

From the highway, one of the biggest landfills in the US doesn’t look at all like a dump. It’s more like a misplaced mesa. Only when you drive closer to the center of operations at the 700-acre Columbia Ridge Landfill in Arlington, Oregon, does the function of this place become clear. Some 35,000 tons of mostly household trash arrive here weekly by train from Seattle and by truck from Portland....

On the southwest side of the landfill, bus-sized containers of gas connect to ribbons of piping, which run into a building that looks like an airplane hangar with a loading dock. Here, dump trucks also offload refuse. This trash, however, is destined for a special kind of treatment—one that could redefine how we think about trash.... _Wired
Here’s how it works: The household waste delivered into this hangar will get shredded, then travel via conveyer to the top of a large tank. From there it falls into a furnace that’s heated to 1,500 degrees Fahrenheit and mixes with oxygen and steam. The resulting chemical reaction vaporizes 75 to 85 percent of the waste, transforming it into a blend of gases known as syngas (so called because they can be used to create synthetic natural gas). The syngas is piped out of the system and segregated. The remaining substances, still chemically intact, descend into a second vessel that’s roughly the size of a Volkswagen Beetle.

This cauldron makes the one above sound lukewarm by comparison. Inside, two electrodes aimed toward the middle of the vessel create an electric arc that, at 18,000 degrees, is almost as hot as lightning. This intense, sustained energy becomes so hot that it transforms materials into their constituent atomic elements. The reactions take place at more than 2,700 degrees, which means this isn’t incineration—this is emission-free molecular deconstruction. (The small amount of waste material that survives falls to the bottom of the chamber, where it’s trapped in molten glass that later hardens into inert blocks.)

The seemingly sci-fi transformation occurs because the trash is blasted apart by plasma—the forgotten-stepsister state of matter. Plasma is like gas in that you can’t grip or pour it. But because extreme heat ionizes some atoms (adding or subtracting electrons), causing conductivity, it behaves in ways that are distinct from gas. _Wired

Curiously, in Cleveland, Ohio, bug-witted politician Dennis Kucinich is leading the rabble in protest against the building of a similar garbage gasification plant. Is it that people Cleveland like trash too much to give it up, or is it that their trashy politicians enjoy stuffing the garbage down their throats too much to give it up?



Blogger bruce said...

is this last step in the plasma simply to reduce the volume? I was hoping to see a net reduction into something useable.
Any word on the net costs?

9:49 AM  
Blogger al fin said...

Thanks for the question. Apparently this particular plasma gasification doesn't generate electrical power, just syngas. I was confusing this plant with another one I recently read about.

This high temperature plasma approach was devised to deal with toxic waste, and apparently works quite well at making such waste quite safe.

As for separating high value products from the gasified garbage, I have heard of schemes for doing that, but I don't think that is done in this Oregon plant.

Future nano-assembler plants may use plasma to atomise waste into constituent atoms, then sort and re-assemble them into valuable products.

I agree that as long as you are taking the trouble to definitively deal with garbage, you may as well turn it into treasure.

8:03 PM  
Blogger Brian Cummins said...

In terms of opponents and politicians in Cleveland opposing plans for a thermal gasification waste-to-energy facility -- the proposed site is in the middle of a dense residential district in a city with a horrible legacy of industrial pollution. Additionally, there is a serious credibility problem with the project, including the manufacture rep that introduced the technology from Japan (Kinsei Sangyo)to the city; and, our city is broke and the $180 - 300 million high risk project could bankrupt our local utility if it goes bust.

Brian Cummins
Cleveland City Council, Ward 14

1:59 PM  
Blogger al fin said...

An interesting insider's perspective, thanks, Brian.

Too bad Cleveland could not have gotten a bit of that Solyndra money that Mr. Obama poured down the drain, to pay back his political supporters.

2:39 PM  

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