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Plasma Waste Conversion June 16, 2008

Posted by federalist in Energy.

Better than an incinerator: Plasma conversion turns any waste stream into glass and elemental gas. In the case of carbonaceous materials, which includes the bulk of what we call “trash,” the process can also produce a surplus of energy. I.e., rather than trucking trash to a dump, we can convert it into synthetic gas, electricity, and vitrified gravel.

(Solid plasma waste still contains any radioactive isotopes or heavy metals in the original waste stream, so it doesn’t eliminate nuclear waste. But at least any toxic metals are locked away in glassy slag instead of slowly leaching out of a rotting landfill. Or, as this patent application suggests, we might go one better and process the plasma before cooling to recover refined high-value metals.)

Popular Science did an article on this last year — excerpts below the fold:

“The best renewable energy is the one we complain about the most: municipal solid waste,” says Louis Circeo, the director of plasma research at the Georgia Institute of Technology. “It will prove cheaper to take garbage to a plasma plant than it is to dump it on a landfill.” A Startech machine that costs roughly $250 million could handle 2,000 tons of waste daily, approximately what a city of a million people amasses in that time span. Large municipalities typically haul their trash to landfills, where the operator charges a “tipping fee” to dump the waste. The national average is $35 a ton, although the cost can be more than twice that in the Northeast (where land is scarce, tipping fees are higher). And the tipping fee a city pays doesn’t include the price of trucking the garbage often hundreds of miles to a landfill or the cost of capturing leaky methane—a greenhouse gas—from the decomposing waste. In a city with an average tipping fee, a $250-million converter could pay for itself in about 10 years, and that’s without factoring in the money made from selling the excess electricity and syngas. After that break-even point, it’s pure profit.

New York City is already paying an astronomical $90 a ton to get rid of its trash. According to Startech, a few 2,000-ton-per-day plasma-gasification plants could do it for $36. Sell the syngas and surplus electricity, and you’d actually net $15 a ton.

Startech isn’t the only company using plasma to turn waste into a source of clean energy. A handful of start-ups—Geoplasma, Recovered Energy, PyroGenesis, EnviroArc and Plasco Energy, among others—have entered the market in the past decade.



1. federalist - May 15, 2009

WSJ column on current “waste-to-energy” trash incinerators notes:

Some 13% of U.S. garbage is burned — far less than the 54% buried in landfills and the 33% that is recycled.

Incinerating a ton of trash emits at least 35% less greenhouse gas and yields 10 times as much electricity as burying it, according to a recent study by EPA researchers.

2. Andrew (not Potter or Coyne) - July 30, 2009

The possibility of recovering industrial and precious metals in household waste (which I’m guessing ends up in the glass slag) is quite interesting. It might make it worthwhile one day to mine existing landfills to recover increasingly rare metals like copper, nickel, zinc, etc. in household waste.

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