3069Views58Replies

Author Options:

Using Plasma Arcs to Deal with Trash Answered

Picture of


"A Florida county plans to build a facility to get rid of their landfills, generate electricity and produce construction material, all using a process called plasma gasification which vaporizes garbage at temperatures hotter than the surface of the sun.
The $425 million facility expected to be built in St. Lucie County will use plasma arcs to turn garbage into gas and rock-like material. It will be the first municipal plasma waste processing facility in the united states, and the largest in the world. Expected to be completed within 2 years, the 100,000 square food facility will process 3,000 tons of waste per day. Fed not only with waste being produced currently, the facility will also begin to process the waste already in the county landfill. Estimates predict that the entire volume of the existing landfill, 4.3 million tons of trash collected since 1978, will be processed within 18 years."

Read More...

It almost seems too good to be true, what do you think?

50 Replies

user
nutsandbolts_64 (author)2010-05-25

It's possible. I wonder if there's any way to increase efficiency. Like, lowering the temperature a bit to exactly the minimal required temp. Something like that...  

Select as Best AnswerUndo Best Answer

user
Masterdude (author)2008-11-23

The arc is probably a carbon arc. I've done some experiments with them at home on a smaller scale using a graphite electrode and also with pencil lead to create a small carbon arc.

Select as Best AnswerUndo Best Answer

user
Masterdude (author)Masterdude2008-11-23

PS: I'm thinking of putting it on Instructables on the SANYO eneloop Battery Powered Contest.

Select as Best AnswerUndo Best Answer

user
TheDeadChemist (author)2008-07-22

Really good idea but how much electricity do you use to melt the trash???

Select as Best AnswerUndo Best Answer

user
firemanfu (author)TheDeadChemist2008-07-23

the syn gas you generate is flammable and that runs a generator to power the plasma , the excess energy going to our houses and such

Select as Best AnswerUndo Best Answer

user
Plasmana (author)2008-07-23

That job must be very stinky and f**king hot!!!

Select as Best AnswerUndo Best Answer

user
new2welding (author)2008-07-03

Help! I just bought Exothermic Cutting Rods to use with my new arc welder to cut carbon steel off a John Deere Bush hog. Did I buy the right thing?? Cant seem to strike an arc. Any advice would be appreciated.

Select as Best AnswerUndo Best Answer

user
Mukund (author)2008-01-28

Syn gas generation is effective at temperature around 1300-1400 C, but plasma arc temperature is around 4000-5000 C. So why we are going for such high temperatures.

Select as Best AnswerUndo Best Answer

user
Goodhart (author)2008-01-23

The article states: The process generates a synthetic combustible gas, which will be burned in turbines to produce up to 120 megawatts of power

but fails to say how much power is used to create the plasma arcs (or at least I didn't see any mention of it). Any idea how much power is consumed in the process?

Select as Best AnswerUndo Best Answer

user

Not sure, but it does say that it will be off the grid...only using electricity it creates.

Select as Best AnswerUndo Best Answer

user

Make that electricity it generates.

Select as Best AnswerUndo Best Answer

user

The law of conservation of energy will then see it wind down eventually ? That is, unless it gets a major "start" creating a large reserve to begin with.

Select as Best AnswerUndo Best Answer

user

Just because it's off the grid doesn't mean that no energy is entering the plant - the trash that comes in provides more energy. Think of it like a coal burning plant, and just replace the coal with trash.

Select as Best AnswerUndo Best Answer

user

Coal, once ignited, will generate enough heat to continue the burn....I am having a hard time getting my mind to wrap around the idea that garbage will contain that much energy. I am not denying it is possible, just having some troubles understanding the whys and wherefores :-)

Select as Best AnswerUndo Best Answer

user
killerjackalope (author)Goodhart2008-01-23

Plastics contain masses of energy, paper etc not so much but alot of waste is plastics and such which have massive chains of hydrocarbons making them very energy rich, if you have a fire go chuck a few bits of plastic packaging on it when it's giving strong steady heat from coal or wood, suddenly it get way hotter when the plastic takes light. Paper isn't as energy dense but it comes out fast, again try the fire experiment, and if you manage to burn metal it's like well, go burn some steel wool/ tin foil/ thermite and see... I can't think of any other large constiuents of rubbish right now, I imagine if glass went on fire it would burn good, meat would burn well as would any food waste, also this would be very sanitary disposal, fabrics are all either plasticky synthetics or probably similar to paper in output...

Select as Best AnswerUndo Best Answer

user
Goodhart (author)killerjackalope2008-01-24

if you manage to burn metal it's like well, go burn some steel wool/ tin foil and see...

But it takes energy to grind things to that fine a consistency too. I am just curious if anyone there has taken the time to measure ALL input and pose it against the output.

Select as Best AnswerUndo Best Answer

user
killerjackalope (author)Goodhart2008-01-24

I don't think the giant plasma arc cares too much about consistency, i just thought the example would be there, I keep meaning to try something but can't find bits and pieces, I'm attempting use the basis of a carbon arc lamp from from 4 2700mah AA's (there's more current than a lantern battery so handy) to try and find out exactly what this stuff can do... and see how long the batteries last, I'm not sure if this system is more efficient on a massive scale or a small one...

Select as Best AnswerUndo Best Answer

user
Goodhart (author)killerjackalope2008-01-24

Well, depending on consistency, or viscosity and bulk as well as the actual material, more or less energy will be needed.

Select as Best AnswerUndo Best Answer

user
killerjackalope (author)Goodhart2008-01-24

complicates then but it would be interesting to see what could be done at home, in fact I suspect it could be a hell of a fun way to cut stuff up... The vaccum bit is asumably the big difference here...

Select as Best AnswerUndo Best Answer

user
Goodhart (author)killerjackalope2008-01-25

There is a "rod" sold for HV arch welders (I have used one), called a plasma cutter, which is little more than compressed carbon rod about 3 inches long and about 1 inch thick. But it wears down, or is "used up" very quickly, especially if cutting anything thicker then sheet metal.

Select as Best AnswerUndo Best Answer

user
killerjackalope (author)Goodhart2008-01-25

hmmm, that's beacause without a vacuum/ inert gases the rod burns too, I might make an attempt at something similar to see what's what, just not sure what kind of power source I need, due to the difference in power sources from the carbon arc lamp and the arc welder... Might hook up an old psu or something similar, need monstrous amounts of current I think, or is it voltage, or both...

Select as Best AnswerUndo Best Answer

user
Goodhart (author)killerjackalope2008-01-25

My arc welder used 250 VAC, but was only a 110 Amp unit. Not much bigger than an industrial strength automobile battery charger/starter, it puts out a rather large wallop. The electric meter spins like a top when I use it. :-) I do believe the "cutting rods" were mainly for bolt cutting, etc. and not really for cutting up, say an automobile body or anything like that. If I could rig something to blow an inert gas (maybe CO2) over the arc, it might limit the oxidation and thus the rod use might be slowed.....I will have to think about that one.

Select as Best AnswerUndo Best Answer

user
killerjackalope (author)Goodhart2008-01-25

Hmmm with all that electricity involved I'd opt for something like argon/nitrogen in case the carbon+carbon dioxide = two carbon monoxide, It's believable under that heat and with electricity there to fill the odd electron gap...

maybe use an old oxy acetelene welder with the inert sheild around the flame, these could just have a wire with element inside the shield of gas...

Select as Best AnswerUndo Best Answer

user
Goodhart (author)killerjackalope2008-01-25

Yeah, I was just thinking "least expensive" *sigh*

I wonder if one could incorporate more then one gas, since when carbon is heated with carbon dioxide at ~1000°C in the absence of oxygen, it becomes activated carbon.

Select as Best AnswerUndo Best Answer

user
killerjackalope (author)Goodhart2008-01-25

oh that could work alright then but when the Co2 runs out the whole thing may go on fire... May be a dry ice bucket as the cutting station and just destroying anything that goes in there, think well insulated and a hole directly above the arc with a cap for extra insulating, note whole thing may go bang...

Select as Best AnswerUndo Best Answer

user
Kiteman (author)Goodhart2008-01-24

Not all metal needs to be ground fine to burn, just to burn fast. When we take the cubs camping, we dispose of as much rubbish as possible in the bonfire. When aluminium or steel drink-cans go in the fire, they're never found in the ashes the next morning. Food cans are thicker, so take two evenings in the bonfire to burn away completely.

Select as Best AnswerUndo Best Answer

user
Goodhart (author)Kiteman2008-01-24

I wonder what alloy your cans are made of. I have seen soup cans over here survive several days in a very hot coal fire already (still being there when the ashes are emptied). I haven't tried that with the "new" aluminum cans, but then, I don't drink sodas most of the time (some canned juices, but again the cans are not anywhere near as thin as those of the soda persuasion :-) . Then again, you might be closer to sea level then we are, so your fire might be hotter... :-)

Select as Best AnswerUndo Best Answer

user
trebuchet03 (author)Goodhart2008-01-23

So I contacted one of the companies that makes this sort of plant a few months ago to get some information about just that... Those plasma torches are not the primary source of gasification, they are a secondary/tertiary process for what doesn't break down (carbon monoxide). The bulk of the gasification is done under pyrolytic/low oxygen conditions. The gentleman I spoke with from plascoenergygroup had said that the more they collect from the initial gasification, the higher the efficiency the entire process is due to less torch usage. I'm still not entirely sure how it doesn't break some sort of thermodynamic laws without breathing gobs oxygen for combustion... But, if it was combustion - it'd be producing CO2 - not CO. All that said - there are small scale projects that are working with a net gain of electricity... The big deal about this project is that: 1. It's the 1st in the US 2. It's the largest project as of yet 3. Have you ever driven in that county? Your God, there's a shit ton of landfills... Not just big ones - a whole lot of big ones...

Select as Best AnswerUndo Best Answer

user
trebuchet03 (author)trebuchet032008-01-23

I forgot to mention steam.... They pump in water vapor....

Here's the chem reactions

Exothermic
C + ½ O2 ==> CO
C + O2 ==> CO2
2CxHy + (2X+Y/2) O2 ==> 2X CO2 + Y H20

Endothermic
C + CO2 ==> 2CO
C + H2O ==> H2 + CO
CxHy + X H2O ==> (X+Y/2) H2 + X CO

Where does this source of abundant energy come from? Lots... and lots... of trash.

Select as Best AnswerUndo Best Answer

user
Goodhart (author)trebuchet032008-01-23

Am I mistaken or is there an awful lot of Carbon monoxide being generated from those reactions ?

Select as Best AnswerUndo Best Answer

user
trebuchet03 (author)Goodhart2008-01-23

Yep - it's the aforementioned syngas ;) Eventually, it ends up as CO2 plascoenergygroup burns it in otto engines to produce electricity.

Select as Best AnswerUndo Best Answer

user
Goodhart (author)trebuchet032008-01-24

Ok, I see now. Very interesting :-)

Select as Best AnswerUndo Best Answer

user
killerjackalope (author)Goodhart2008-01-23

Carbon monoxide is a highly combustible gas not just bad for us bit remember if moleceules etc were people carbon monoxide's sole purpose in life is to bond with and oxygen moleceule because it's an unstable compound as the eletrons and protons don't add up, the same reason for why it's bad for us, haemoglobin is used by the body to hold and transport oxygen by bonding with it but when carbon monoxide gets in on the act it permanently bonds to haemoglobin killing us...

Select as Best AnswerUndo Best Answer

user

hemoglobin is used by the body to hold and transport oxygen by bonding with it but when carbon monoxide gets in on the act it permanently bonds to hemoglobin killing us

It's also used for packing meats - for the very same reason it would kill living meat people/products :)

Select as Best AnswerUndo Best Answer

user

yep, I daresay that it would murder bacteria that can work aerobically... basically it's an all round murderer, if moleceules and atoms were people carbon monoxide would be an absolute psycho, then caesium would walk up and kick its head in, after that caesium is mowed down in a random driveby involving hydrogen and fluorine, all the while helium and nitrogen just sit and watch... God I just made sense of why my chemistry teacher hated me... I got A's then talk crap like that...

Select as Best AnswerUndo Best Answer

user

Aerobic bacteria isn't the concern so much (anaerobic is what makes spoiled meat smell... spoiled). The CO keeps the meet red by preventing oxidation (brown meat).

Select as Best AnswerUndo Best Answer

user
killerjackalope (author)Goodhart2008-01-24

I would believe that on a large scale the plasma arc would be an efficient way of doing it, the heat it creates alone puts it at the top of its game, on the other hand 1000 toaster hacked into a super heated grid may do a similar job for less cost, you make a giant toaster of doom screen that gets fed giant block of rubbish which are then dice into handy blocks that can be used for anything... Yay kids compressed waste blocks fight!

Select as Best AnswerUndo Best Answer

user
Ferrite (author)2008-01-24

This is something similar but it creates oil instead link

Select as Best AnswerUndo Best Answer

user
alvincredible (author)2008-01-23

how does it get to temperatures hotter than the sun!? i just don't understand how we can control heat of that magnitude. ahha... goodness science is cool. i bet we're going to eventually have people colonizing the sun.

Select as Best AnswerUndo Best Answer

user
Kiteman (author)alvincredible2008-01-24

The surface of the Sun is around 6000C. Sounds big until you realise that the temperature of a lightning bolt is around 30,000C.

Select as Best AnswerUndo Best Answer

user
Goodhart (author)Kiteman2008-01-24

Yep, and people have been hit by them and not vaporized. So size DOES matter sometimes :-)

Select as Best AnswerUndo Best Answer

user
Trebawa (author)alvincredible2008-01-24

Nothing is impossible, I guess... But i must say it would probably be pretty hard to colonize such a gaseous and massive object without being incinerated, crushed, or unable to build. Not to be a wet blanket or anything.

Select as Best AnswerUndo Best Answer

user
Goodhart (author)alvincredible2008-01-23

One of the ways it is controlled is that is it a wee bit smaller in size then the sun :-)

Select as Best AnswerUndo Best Answer

user
NachoMahma (author)2008-01-24

. Here's some of what I learned during 14 years of working at a hazardous waste incinerator (natural gas fired). The actual process will vary from plant to plant, but the basics should be the same.
. How efficient the process is depends on the materials being burned. If you are burning something with a low BTU value , it's going to take more added energy to break it down. Conversely, if you are burning high-BTU materials, you may have to throttle the process to prevent the system from getting too hot. Balancing the ratio of low- and high-BTU feeds is crucial to efficient operation.
. The initial "burn" boils off the volatiles and breaks down the organic material into C, CO, CO2 ,H2 , HCs, &c (plus NOx , &c), which are then converted to CO2 (TANSTAAFL) plus some CO and other gases since the process isn't perfect, in a combustion chamber, where the burning (oxidation) actually occurs. The remaining ash (dirt, concrete, metal, stuff that doesn't burn well), supposedly pretty innocuous at this point, is landfilled.
. When burning high-BTU materials, all you have to do to run the combustion chamber is supply O2 (BIG air blowers; lots of energy). When burning low-BTU materials, you have to add a LOT of energy to get the gases up to the required 2000+oF.
. The exhaust gases are extremely hot and have to be cooled before they can be handled. Lots of energy input.
. Most waste streams contain Chlorine, so the exhaust gases have to be scrubbed of the resulting HCl. This takes a lot of energy (and produces quite a bit of waste NaCl).
. Moving all those gases through the system requires a LOT of energy.
. Industrial wastes are often high-BTU liquid hydrocarbons and can be used directly as fuel to run the system (less electricity or NG required) or fire steam boilers.
.
. All in all, it's better to make less waste and recycle when possible. :)

Select as Best AnswerUndo Best Answer

user
Patrik (author)NachoMahma2008-01-24

Thanks, NM!

It's important to keep in mind that plasma gasification is *not* incineration, even though I compared it to that earlier (because all of the same contaminant are present, and have to be dealt with). In this process, the waste is heated in the absence of oxygen. As a result, you don't get a burning as in incineration, but a pyrolysis reaction, where any organic material is broken down into gases.

The chemical reaction is actually very similar to steam cracking of oil, coal or natural gas, e.g. C + H2O → CO + H2.

The resulting gases have been termed syngas, from synthetic gas, and can be used as a gaseous fuel as an alternative to natural gas. Syngas typically consist of CO2, CO, H2O, H2 and some CH4. The CO2 and H2O can be scrubbed out, or the flammable gasses extracted separately.

Syngas can also be turned into a synthetic petroleum substitute through the Fischer-Tropsch process - essentially putting these small gaseous molecules back together into longer hydrocarbons. Interestingly, it's this kind of ersatz fuel that drove the German war machine in the second world war - Germany has little in terms of oil resources, but has lots of coal: coal -> syngas -> synthetic petroleum.

The same sort of process is also proposed to create new biofuels: biomass (switchgrass, corn stalks, etc) -> syngas -> synthetic petroleum.

Select as Best AnswerUndo Best Answer

user
Patrik (author)2008-01-23

Here's a nice article that digs a bit deeper into the pros and cons of plasma gasification:

Is it really possible to generate clean energy by incinerating garbage?

And here's a document summing up some of the main problems with the technology, from the "no incinerators in our backyard" camp:

Gasification, Pyrolysis & Plasma Incineration

The upshot: this is a more advanced version of the trash incineration technology from a decade or two ago (remember dioxin?). The big difference is that this new method produces an intermediate "syngas" fuel which can be cleaned up, stored and transported separately. You still need to deal with stuff like chlorine and heavy metals though.

A promising technology, but don't expect a panacea...

Select as Best AnswerUndo Best Answer

user
trebuchet03 (author)Patrik2008-01-23

You still need to deal with stuff like chlorine and heavy metals though.

Apparently some companies have taken care of that already... Something about quenching IIRC... In any case, those emissions are manageable...

If it gets rid of those stupid dumps - that'd be quite awesome... And make my drives home less stinky :p

Select as Best AnswerUndo Best Answer

user
LinuxH4x0r (author)2008-01-23

I want to know if it can be done on a small scale? At home? powering trucks? Great invention! I hope it goes mainstream soon!

Select as Best AnswerUndo Best Answer