Plasma Arc Gasification: turning garbage into gas

(Updated with new research 1-29-08)
Plasma Arc Gasification is a new waste disposal technology that turns garbage into usable byproducts without burning it. The heart of the PAG “plasma converter” is its “electrical arc gasifier,” which passes very high voltage electrical current through two electrodes, creating an arc in the space between them.

Inert gas under pressure is passed through the arc into a sealed container of waste material [garbage]. Temperatures as high as 13,871°C (25,000°F) are reached in the arc column. The temperature one meter from the arc can reach ~4000°C (~7,200°F). At these temperatures most types of waste are broken into basic elemental components in a gaseous form, and complex molecules are atomized – separated into individual atoms.

25,000ºF is hotter than the surface of the sun.

The byproducts of PAG are:
1. Syngas, a mixture of hydrogen and carbon monoxide. The plant scrubs the syngas and uses two-thirds of it to generate the electricity that powers the plant. The remaining one-third is sold to utility companies. Syngas can be produced from just about any organic material, and PAG is only one method of producing it.
2. Heat. The uses of this byproduct aren’t addressed in lay sources, but presumably it could be used to power a steam turbine in the plant, generating more electricity.
3. Slag, a solid residue resembling obsidian. Once it’s cleaned of contaminents, slag can be processed into bricks, synthetic gravel or asphalt, and other materials that we currently mine out of the ground.

What is the potential of PAG to reduce the stream of trash landfilled each year? Tremendous–if the gas and slag can be cleaned up–because PAG doesn’t burn trash; it gasifies it in a closed-loop system. Burying garbage in the ground is primitive technology with numerous harmful effects that aren’t taken into consideration when figuring cost per ton. No matter how miraculous the liner material in today’s modern landfills, they all eventually leak and dump a nasty toxic stew into the groundwater below.

Currently there are no large-scale PAG plants processing municipal waste in the U.S.–the ones in Tallahassee and St. Lucie County, FL, are the closest to coming online and according to this article they’re still in the permitting phase. I believe there are some very small U.S. operations being used to process medical waste, which the process is ideal for, as it obliterates every possible contaminent.

This Slate article does a nice job of summing up the pros and cons of the process:

So, why doesn’t every hamlet in America do away with its landfills and build one of these wondrous plants? The plasma gasification industry claims it’s mostly a matter of economics: Burying garbage has long been a lot cheaper than zapping it, even if you factor in the money to be made selling electricity. Landfills charge municipalities an average of $35 per ton of trash; according to a recent study in Hamilton, Ont., dropping off a ton of garbage at a plasma gasification plant would run $172 per ton.

Plasma gasification companies dispute this figure, contending that their method has become more affordable because of increasing efficiency in electricity generation: Canada’s Plasco Energy Group, for example, says that 46 percent of zapped waste now becomes energy, compared with 18 percent with earlier plant designs.

This is the cost/benefit issue that led Honolulu to reject its plant initially as mentioned in the Wikipedia piece linked above. I’m not impressed with the 46 percent efficiency figure–it needs to improve, and it probably will, because this technology is still in its infancy. I also think the cost/benefit ratio will pull even with and then surpass landfilling once the demand for electricity goes up because of the switch from gasoline to electric transportation.

This USA Today article lists some of the environmental questions surrounding PAG. It says that the facilities already processing garbage in Japan are doing so on a much smaller scale than the Florida plants would. Japan’s air quality standards are slightly stricter than those in the United States. If the plants are passing inspection over there, then critics can’t very well say the process is unavoidably dirty. The Slate article has some limited material on cleaning up the gas and slag byproduct. Proponents claim that burning Syngas produces CO2 emission on par with a natural gas power plant–pretty low, in other words.

One criticism of PAG worth consideration is that it provides an excuse for people to keep pumping out trash. The biggest opponent is the Global Alliance for Incinerator Alternatives, (GAIA) a very vocal and well organized nonprofit with an international presence. They’re quoted in the USA Today article:

We’ve found projects similar to this being misrepresented all over the country,” said Monica Wilson of the Global Alliance for Incinerator Alternatives. Wilson said there aren’t enough studies yet to prove the company’s claims that emissions will likely be less than from a standard natural-gas power plant. She also said other companies have tried to produce such results and failed.

GAIA was formed to fight traditional trash-burning incinerators being dumped into third-world countries, which is a legitimate form of NIMBYism. It raised red flags with me that a plant is being proposed for New Orleans (which has become a third world country of its own)–but then there has to be tons and tons of flood trash to get rid of down there, some of it hazardous waste. Why not process it with PAG and get some use out of it, as long as the people of New Orleans benefit from the money saved?

GAIA has said that PAG plants in Australia and Europe were “closed” because they couldn’t meet emission standards. This quote is all over the internet, but in two days of exhaustive searching I haven’t come up with anything resembling a primary source.

Here’s my quarrel with GAIA: it’s immoral to block a developing but basically sound technology because you want to modify the public’s behavior. Humans will always produce trash. I’m about as far from advocating Friedman free market economics as a blogger can get, but trash disposal one area where the marketplace will modify our behavior effectively, because the oil crisis is about to make wastefulness very expensive.

I do suggest that communities hold back on offering public funds to PAG companies that want to locate in their area until PAG has proven itself. The glut of ethanol plants is a caution against committing public money to an economically volatile technology, no matter how promising it might look.

Did you know that a natural latex pillow is 100% biodegradable?

Over at Blogging for Michigan, AikoAdam has written a nice post on PAG.


5 responses to “Plasma Arc Gasification: turning garbage into gas

  1. We don’t have to dramatically change people’s behaviour to reduce our environmental impact. People are separating their trash now for recycling- not demolecularizing, but recycling. They seem to be handling the change fairly well. There is no reason we can’t make it easier to recycle by reducing product packaging. Products sold today have more packaging than product. Gassification might work out well for clean energy and safe building material, but we will always need material to make minimal packaging.
    We have to get away from using raw materials as they are becoming less available(and more expensive).
    PAG sounds good, but even that cannot compare to emission-free wind and solar energy.
    Building material, eh? Hmmm.

  2. As an example of using less, Ireland just outlawed those godawful plastic film bags that this country uses about a billion a year of, after three or four years of slapping a mandatory .33c price tag on each one you take home from the store, just to warm people up to the idea of bringing their own canvas bags when they go shopping.

    All the plastic we use for packaging purposes is about to get very expensive, as it should be. The way I look at PAG is just one of the many ways in which we need to become energy misers. First we reduce the waste stream by conserving raw materials and reusing when possible. The waste that can be conventionally recycled gets recycled. Finally, the stuff we can’t take care of in one of the two above ways gets atomized with PAG.

    Of course, in real life, the process won’t happen all at once–it’ll go where the money is first. Some leadership from government to guide it in the right direction regardless of profit potential would be a good thing.

  3. I believe this is a technology that will help relieve us from landfills and incinerators that are wasteful and produce a plume that not only smells but in some cases are high in emissions.
    I also researched the “closing” of the German facility (I live here) and all indications point to a political reason/background due to already vested waste companies and state politicians being removed from a very lucrative business.
    I might also add that the Germans recycle up to 90% but don’t re-use all that recycled material and the rest ends up being burned or in landfills.
    The city of Ottawa just moved forward with a 400 tonne-per-day facility (by Plascoenergy) after running a test 100 per-day that produced great results. Port Moody is also working with the company on a due diligence for the same system.
    With energy prices climbing and landfills becoming scarce, this system (which can also use sludge from water treatment plants, hazardous materials, tires, almost any waste) can elliminate the waste, produce electricity and keep emissions low enough to be competitive if not better that what we have in use today.
    In third world countries were modifying behavior will take years, and electricity and clean air are scarce (due to open trash burning) this would be an excellent investment.
    We need a combination of solutions for waste and clean energy generation and in the developed world this could be one more piece of the puzzle.

  4. What interests me about this technology is that I believe it can neutralize the prions that cause mad cow–obliterate them, which other sterilization methods can’t do. It can also neutralize toxins, like river sediment contaminated with PCBs. And if there’s any hope of cleaning up landfills and preventing them from leaching and contaminating water sources, I’m all for this technology. Anyone know of a way to invest? I am fired up about this technology.

  5. @jessinwis–yes, this process reduces trash to atoms, so any toxins would have their molecules blasted into particles. It’s like putting our trash on a spaceship and shooting it into the sun–except that we get to keep and use the energy.

    I’m working on a series of posts about investment in cutting edge technology, particularly syngas processes (of which plasma arc gasification is one). Currently these companies are mostly funded by private equity, but a lot of things are going to change in the next few years, and I see some great opportunities for investors to get in on the ground floor.

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