How Plasma Torches Work

about something that's inspired by a little listener mail. This listener mail comes from Damon. Damon says, I was just wondering how plasma cutter works. Is it something to do with electricity? Yours truly, Damon, Damon. That was very nice and short and to the point. So we're going to answer your question. Yes, we're gonna go into more detailed than just the fact that yes, it does use electricity.

So plasma cutters are a it's just one um one use for a plasma torch, and a plasma torch is a device that uses a usually an inert gas uh pressurized pushed through a nozzle and at the nozzle, there's an electrode that's shooting off pretty powerful electricity, which turns the gas into what is called the fourth state of matter plasma. Oh wait, no, here in my notes and says there are five states and manners solid liquid, gas, plasma and New Hampshire. Well there you go. That's the

fourth state, the fifth state matter. Oh my gosh, you get to answer that, listener mail, that's what you have just earned for yourself, matter in New Hampshire. Moving on, So plasma. Plasma is an ionized gas. We've talked about it before on this podcast because it does factor into other technologies. But it's a it's a gas that has free roaming electrons, which means that it conducts electricity. Um.

It also can quote unquote burn really really hot. Yes, as a matter of fact, hotter than the surface of the sun. Yes, we're talking like six thousand degrees celsius. That's um. That's pretty toasty. And uh, the it turns out this is really really handy for things like cutting through material or um. We're going to get into a really cool application in a minute about how you can use a plasma torch to turn garbage into energy. Yes, but let's start's start off slow here. Um, So you're

using this ionized gas. It's burning at this really high temperature. It actually breaks stuff down in a process that we call molecular dissociation, which literally means that it's starts to break down the molecules because the energy that they absorb is so great the molecular bonds can no longer hold, right, so it comes apart, right because normally there is a cloud of electrons uh, circling the nucleus of the atom.

And at that at that point, the electrons are more loosely bound and sometimes split off, right, and you end up with with much more basic particles as opposed to molecules. And it doesn't use combustion, so that's not it's not burning like a traditional torch. Uh. You know, a traditional torch, you need a fuel, you need heat, and you need air, yeah, oxygen, and you don't need oxygen for uh, for a plasma

torch to work. Um. And so it's it's using a it's using heat in a process that we call pyrolysis. All right, now this is when technically now this is for organic manner, This is not for inorganic matter. Different thing entirely right. So pyrolysis UH is a preceived process in which organic matter breaks down and decomposes. Now when you apply a plasma torch to organic matter, pyrolysis happens um, let's say, on an accelerated basis, like practically instantaneous as

opposed to taking years and years and years UM. So this means that plasma torches are very useful for lots of different environments. For example, underwater, you could use a plasma torch because again you're just shooting out gas and you're injecting it with electrons essentially, So you could use a plasma torch to cut through material underwater and not have to worry about the fact that oxygen. You know, you have a real hard time lighting a traditional torch

on the water um. And it's really good for cutting through pretty much anything. I mean, at that temperature, it's gonna managed to make its way through tons and tons of different stuff. So we do find them very useful in lots of different applications. And the one that I really wanted to talk about, which really it goes beyond the plasma cutters, which you know, that's interesting enough, but

I really wanted to talk about plasma waste converters. Okay, do you want to just jump into that then sure, Okay we can. I mean unless you had something more to say specifically about plasma cutters. Well, no, I was I was going to bring up when we started to learn about them, because it really wasn't even all that long ago during World War Two that they discovered that

this could be, that this could be possible. Um. Basically what was going on was, uh, you know, the American war effort required a lot of different kinds of machinery to be fabricated very quickly, and they discovered this, uh, this arc process that we've been describing basically by uh, you know, just the techniques they were using then too.

They started off with you know, arc welding, and uh they were able to uh they realized that you know, charging the gas with the aren't made a barrier around where the weld was UM, and it predicted it from oxidizing, which is very useful. UM. And uh it also made very very clean cuts, which is why they they're using it for uh plasma torches or using plasma torches for you know, cutting purposes. And then um, you know, in

the nineteen sixties. Basically what would happen is, uh they realized that once you speed up the flow of gas um and cutting down the size of the hole through which it is being released, you could it would keep higher temperatures than any other type of of welder. And um, you know, that's exactly when they started cutting was because you know, they discovered the properties of using this method

uh in in the welding process. But then once they started experimenting with it some more and found out that it makes it's awesome for cutting, and it can cut through all kinds of different heavy duty metals that you wouldn't be able to cut so finely using any other process, and so simply really um so that's why it's so

so awesome for that. I just wanted to touch on the history of it a little bit because, um, you know, this is not something we've known about for you know, a long time like some of the other technologies we talk about. Sure, and it's only been a couple of decades since someone thought to to apply it to waste management. Yeah, that's even newer. So I'm sure you're all aware that that waste management is a huge issue. You know, it's

it's a problem in a lot of different communities. We talk about pollution, we talk about the the need to create large landfills dumping sites. Then of course there are the big dumping sites out in the ocean, so we don't really like to think about, but they're out there. Um. And we've you know, people have tried to come up with lots of different ways of solving this problem, everything from just cutting down the amount of waste we generate, which you know, that's part of it, that's important, big

part of it. But but we're getting new people every day, and even if you start cutting back the amount of materials you're you're consuming, the number of people that are added to the planet kind of makes that a very slow process. I mean, eventually it all catches up to you again. So there are other things you can look at, like you know that people have tried to burn trash, but of course that often will generate other kinds of pollution,

including pollutants that will eventually cause acid rain in the future. Um, and that's clearly not good either. And then there are other, you know, semi outlandish proposals like shooting it off into space so that we you know, we stop polluting the Earth. We'll just start polluting space everything else not Granted, space

is big, I mean really big for your stuff. There's always space, and at any rate, assuming you don't want to just you know, find new places to throw st of a way, you want to find a way of getting rid of it. And that's where plasma waiste converters come in. Now, a plasma waist converter has at its heart a plasma torch. Yeah. Now the plasma torch is inside a furnace. Uh. And inside that furnace, what you

do is you you dump garbage and there Uh. Normally the garbage has to go through a process where it gets crunched up into smaller bits first. But once it goes into the furnace, the plasma torch causes it to to transform. And there are two different transformations that happen to the organic material. You have volatilization, also known as gasification. The organic material gets turned into gases, synthetic gases or sin gas, right, and then you've got the inorganic compounds.

So anything that's not carbon based, essentially is what you're talking about here. Um, it becomes vitrified, turns into slag. It kind of looks like law. When it's coming out of a plasma waste converter, you know, it's a bright reddish orange glowing liquid material and as it cools, it becomes if you were to allow it to air cool, it turns into this kind of hard, glassy, rocky substance. It kind of looks like um, obsidian lava connection Again, Yeah,

it looks a lot like obsidian. So if you've ever seen a volcanic rock, that's a lot like what the the the cooled version of slag from a plasma waste converter looks like and um. So that's so you've got the volatilized material and the vitrified material. And uh, actually, depending on how you cool that slag, it can turn into many different formats. Like air cooled, it looks like those little rocks like I was mentioning. If you cool

it with water, it turns into these little pebbles. So they don't like it doesn't look like a little rock. It doesn't like rocks is in you know, jagged edges or anything like that. It's just it's almost like a fine sand. And then if you blow compressed air through it, which I would not recommend anyone try to do if they had somehow managed to build a plasma waist converter,

because it's scary to look at. I was I was going to say, how many, just how many of our listeners do you think actually have a plasma waste converter in their backyard? You know? I mean, it's good that you're warning pits, but I will admit it's a hell of a do it yourself project. Okay, but you know,

just saying. But anyway, if you were to somehow find a way where you could blow compressed air through the stream up slag as it's coming out of the plasma waste converter, it turns into this very very thin material almost feels kind of like cotton or insulation, and uh it's called rock wool and um it's I actually saw a video of this stuff being made. It's just these two guys standing around. Guy from Georgia Tech actually someone I chatted with quite a bit when I was writing

an article about this um. But the video of him blowing compressed air through this molten stream of material was really impressive and kind of scary because it's just these two guys standing there building compressed air through material that's so hot that it would do you serious arm if you touched it. Right. Um, but but it turns into rock wall, which turns out to be a really good insulator and uh and could be a way of making

money off plasma waste converters. But well, we'll talk a little bit more about how they can generate in cash. So anyway you get this, you put the garbage through this stuff, those are the problems. You get the end gas and the slag, and you end up reducing the

amount of weight and space of that garbage significantly. One other benefit to using plasma waste converter to get rid of your stuff is that, uh, you can treat all kinds of garbage in there that you might not otherwise want buried in landfills that because of uh, you know, it could be dangerou For example, medical waste which could

be infectious. Um. Basically, medical waste can be treated in a plasma waste converter and it you know it's inert once it's done, because you know it it breaks materials down to the point where they are no longer what they once were, and you know it's no longer dangerous. However, there are limits to how not dangerous things can be. One of the things that you cannot just grab a bucket and throw into the plasma waste converter is spent nuclear rods. That is what they call in scientific terms bad.

So if you are to do it yourself er and you've built your plasma wast converter in your backyard, not only should you not blow compressed air through the slag, but also please don't put any spent nuclear rods in there. Yeah, let's be responsible. Okay. Then, so you know I mentioned that the weight and the volume are reduced. Yes, it's

actually reduced by a very significant amount. I mean, you granted a lot of the stuff is being turned into gas, and then a lot of it is being turned into the slag, and the slag is much more dense than the original material usually that you put through this. So in general, uh, the weight of the slag ends up being about the weight of the original waste you put in there, and the volume is five cent so in other words, it takes up much less space. It's very dense.

Um Often the slag, if it's dried so that becomes the rocky substance, could be used in in building materials, so like concrete or even just just using it as you know gravel really. Um. But the neat thing about these these plasma waste converters, now there are on a whole lot of them out there right now, there's only a few. There's a couple in Japan, and there's one that was being built in Florida. I actually haven't looked to see how the progress has gone with that one.

It should have been operational by now. Um. But these the really cool thing about these is that not only would they eventually be able to taken all the incoming garbage coming into the landfill to process, but some of them operated such a huge capacity We're talking thousands of tons of garbage every day that not only could they handle all the incoming garbage, but could actually make a dent in the existing garbage at the landfill. Why are

you going around denting garbage? I'm just pointing out that if we were to invest in this technology, eventually we could reclaim landfills. You could actually end up using them, uh enough so that the landfill is gone because you've you've consumed all the garbage in there. Now granted you would still be getting income and garbage, so it's not like you could just shut down. You know, you wouldn't.

These these aren't like, uh, these aren't facilities that you you start up and then like twenty years later they're insignificant or uh are obsolete. No, you would still be taking incoming garbage and and still gasifying or vitrifying it. But you could reclaim all those landfills. That's pretty impressive considering that. Yeah, I mean, think about all the different communities that really fight to have to to to prevent

landfills moving in. Um. It would be a good way to reclaim all that land use it for something else once it's cleaned. UM. And one of the really cool uh ideas I saw was too you know, if building a whole plasma waist center is too much money, um, you could always make a portable version. Oh yeah, this

one's kind of scary. So here's the portable idea. The portable ideas that you go to a landfill, you drill down into the landfill, You insert into the hole a plasma torch on the end of a very long pole. You cap the hole at the top with a chamber that can capture escaping gases and yet light that sucker up seriously. Yeah, the landfill itself becomes the furnace for the plasma waste converter. Instead of building a furnace around

the torch, the landfill itself access and furnace. And again, since you're not using combustion, you don't set fire to everything. There's no oxygen down there, at least not enough to actually create a fire. You're just you're consuming the landfill from the inside out. Yeah, I had no idea that was possible. Yeah, and I don't know that anyone's actually done it yet, but I saw a really cool presentation

of it at Georgia Tech. Well. Um, I would also assume that since plasma cutters are available for people to buy, that this is something you really wouldn't want to try. That you theoretically could possibly do, you know, try to burn your own garbage. This would be seeingly bad idea. And I'll tell you exactly why it's a bad idea, Okay, beside the fact that you would possibly maim and or kill yourself. Yeah. Um, the gas that's given off the

organic gas is not necessarily harmless. Now, we talked about how the materials get broken down into into very inert uh forms that mainly pertains to the slag, all right, so that when the slag comes out. One of the one of the big concerns about plasma waste converters is there's a lot of stuff that's in garbage. And there's mercury, there's lead, there's all these materials that eventually, you know that you only break them down so far, right, it's

not like you can change the atoms. Um. Well, there was a worry that maybe the slag, the stuff could leach out of the slag get into the groundwater, and then you really just traded one problem for another, really serious problems. It looks like the material doesn't leach out anything, so that concern is gone. But stuff that turns into

a gas that is toxic that remains. And it's only through a process of scrubbing that gas by putting it through a series of filters that you start taking out the harmful elements that could otherwise, uh, you know, cause serious damage and or kill people. Right, But it's it's mainly hydrogen and carbon monoxide off, but there's other stuff that can be carbon monoxide is not the healthiest stuff

in the world either. But granted, you know a little whiff of it's not gonna instantaneously kill you, but yes it is. It is toxic, but yeah, that's why if you look at a full plasma waste converter system, there is a after you. After you've burned everything, there's still more to the system. Besides that. You usually have at the front of the system, you've got a conveyor belt carries the garbage to some grinders which grind it down into tiny bits. The tiny bits go into the furnace.

The furnace burns that stuff up or melts it. I guess it's better way of putting it. Gasifies it. The gas goes into one part of the system, and the slag gets drained off. Now the gas usually we'll go through a cleaning system like I mentioned, where it will go through uh usually a spray of water which helps cool it down because this gas is incredibly hot after coming out of the furnace, and then it goes through it also scrubs the gas out of some pollutants and

some particulates that are usually included in the gas. And then I will go through a filter that has um base in it. That's because the gas can have acidic elements in it and of course, when you mix an acid with the base, what do you get? Um? Shoot, pH seven? What is that? All right? It's neutral. But the more important thing is you get a salt basse plus acid equal salt. Um. That's okay, that's okay. The only reason I know it is because it's in the

paragraph right in front of me. I forgot that. It's been a long time since I have had high school chemistry. Um. But yes, all of our listeners, of course we're screaming it out. I know they were, like them are in high school chemistry right now. Hey, guys, how's it going anyway? So, yeah, you get you get a neutral salt as a result, and uh, it goes through this cleaning process. It's usually several steps so that you have ended up with a synthetic gas that can actually be used as a fuel.

So now we're getting to why our how a plasma waste converter can be profitable because we we know that environmentally this sounds like a fantastic idea. I mean, you get rid of all this garbage, you end up with some synthetic gas that can be used as a fuel. You end up with some slag that's a nert it sounds like a dream come true, right, more or less, I mean better than a bunch of big pile of

garbage sitting out back. Right. So, but we know that the world revolves around making cash money pin Is Nickels, Dames, Cordas, dollar bills, hundred dollar bills. I bet no one got that reference anyway, So it is all about the Benjamin's. It is all about there you go, they'll get that reference. So anyway, the the the way that they can make cash is that one. There's this, uh, there's these this

thing called tipping fees. Now. Tipping fees refer to the amount of money or the money that people have to pay in order to be able to um to cart garbage to a landfill. All right, well, right now, waste management's kind of almost a monopoly, so the landfills can pretty much dictate the tipping fees. There's no real competition there, there's no incentive to lower tipping fees. Populations are growing and consumption continues to grow. So really, uh, these these

fees are getting higher and higher. It's getting more and more expensive to to just pay to have garbage ship to landfills with plasma waste converters, you're not worried about running out of space anymore. In fact, you're making space. So the tipping fees could be negotiated to a lower level. I'm sure that would make the waste management companies really happy. Yeah, yeah, when it comes down to making money, and it's but

then it's it's also stopped making money. It's also really hard for them to justify, uh, protesting, because protesting the fact that hey, we're saving the world but we're not making as much money doesn't get you a lot of sympathy, as it turns out. But anyway, so they could negotiate tipping fees, and tipping fees would be part of what

how they would make money. They could also sell the slag, however, in whatever format, whether it was being used as a uh you know, like a gravel or a building material, or if they were making rock wool, they could sell it like installation. It's apparently extremely effective as installation um. And then with the gas, they could actually generate enough gas from destroying this garbage to create fuel to run

the facility itself. So in that sense they don't need to consume power from the power grid, and in fact they could potentially create enough gas to sell power back to the power grid. That would be nice because you would uh generate this gas, you could run a generator

and then generate electricity and add it to the power grid. Um. A lot of people have asked me in the past, does this mean that it's some sort of magical kind of of way of generating energy, because you think about that, sounds like how can something generate more energy than it takes to run it? Um. The answer to that is it's it's using fuel. It's just all all it's doing is converting fuel from one format into another. Um, it's not you know, it's not like a perpetual motion machine.

It's kind of like the idea of well, if an oil drill consumed more energy than it generated by gathering fuel, it would make no sense to drill for oil, right, because what you do, think, yeah, because you'd have to pour more energy into the drill then you would get out of the fuel your Right, it's the same sort of thing. Think of it like an oil drill. It's not like a perpetual motion machine. It's more like an oil drill because you're gathering fuel up from garbage. Right.

So um, yeah, that's the way that they can make money. Now, getting the initial investment to build one of these things has been tricky because they are expensive. How could that possibly be? So? Yeah, well, mostly because they're all customized. Yeah, that's true. Um. One of the things in the article on on plasma waste converters it is the fact that every single plant that there is in existence now is

custom so it's all unique. Yeah. And it turns out designing a facility from the ground up costs lots of money. Does seem pricey? Yes? Yeah, And um, well I'm sure you could get some really nice parts with clean edges if you use plasmic cutters. Well. And it's also a matter of educating the communities about what the plasma waste converters doing, the benefits of it, and any potential drawbacks, because you have to be completely upfront about that. I mean,

otherwise people are gonna worry about it. I mean, let's put it this way. If you were told, like if you had no knowledge of plasma waste converters at all, and you were told, hey, I want to build this facility that at its heart is going to have a torch that burns bright heart hotter than the surface of the sun. It's going to give off gas which could potentially kill you, and molten slag um, And we're just gonna throw your garbage in there. You all right with that?

You might have a little pause for right, I mean, unless you just had lots of garbage and you're like, dude, anything to get rid of this stuff. Yes, but yeah, so it's it's a little intimidating at first too. It takes a little time to understand this. But just to give one last little bit of of um kind of statistics. This is what Chuck would do if he were here. Ah, he's the statistic guy. Uh. The the proposed facility in

flow its supposed to be at St. Lucy County. Like I said, I hadn't looked to see I should have checked to see if they had built it and should

be up and running by now. Um. But the idea was that it would be able to process up to a thousand tons of garbage each day and generate sixty seven megawatt hours of power each day with a net output of thirty three megawatt hours because the course has to consume some to keep going um, and that it could eventually scale up to three thousand tons of ways per day by adding a couple of modular units to the already existing ones, and that um that potentially it

would be able to completely eliminate the landfill in less than two decades and it could power thousand homes. Serious, Yeah, just from garbage. So that's pretty cool, I think. Okay, so, our our sister site Tree Hugger says that the plant in St. Lucy County, Florida is expected to be online by not the future, but it hasn't happened yet. Well, I look forward to reading more about that because I

find the whole the whole model to be fascinating. Yeah, it's pretty neat and potentially a real game changer, but you definitely don't want to be right next to it. Well, I definitely don't want to be in the furnace. That wouldn't be in there for very long. Yeah, and I just wonder. I imagine you'd probably have to stay pretty far away from it. I'm sure they have insulation, but yes,

actually they are very heavily insulated. They have water cooling systems that run through Because you think about that, like if it burtens hotter than the surface of the sun. What the heck could withstand that kind of heat? You know, just just sort of a trivia fact really, but something that was in the article we didn't I don't think you mentioned the slag, which isn't immediately drained off, can

actually help continue to heat the furnace. Yes, which is which is also pretty neat because once it's converted, it's already producing energy heat energy, and it's well producing it, it's maintaining and I guess, and actually the heat itself can be recaptured and used to generate or to turn well, it ends up converting water into steam, which then turns turbines,

which rates energy electricity specifically. And uh so, yeah, there are a lot of different ways that you could create electricity using this system, all by just you know, getting rid of some garbage. And we don't have too much of that running around anyway. We try to trim it from this podcast whenever possible. Well, that's that's why I've been missing from the last six anyway, Well I have, I have. Now we've we've done plasma cutters. We talked

about plasma waste converters. I want to move on to a second round of listener mail now, This listener mail specifically comes from Brian, although we received other people asking the same question, including Dante, so I wanted to give a shout out to both of them. The question is you spoke a lot about how listening to music with earbuds can lead to hear loss if volume is too high. But what about listening to speech like the tech stuff podcast. Oh well, I may lose hearing, but I would gain

smarts Brian. Yes, Brian, any loud noise, especially a sustained loud noise, even even if there are short breaks like in speech, if you listen to it over a stretch of time, like for instance, the typical tech stuff podcast, you can cause hearing damage. Does not have to be music, does not have to be a C d C, does not have to be a jackhammer or jet engine. Yeah, loud noise bad for years, right, So just in general,

just try and keep those ears safe. Okay, And if any of you have any questions, comments, you have a topic you want to suggest, you just want to say hello, you can write us. Our address is tech stuff at how stuff works dot com and Chris and I will

taught you again really soon. If you're a tech stuff and be sure to check us out on Twitter or tech Stuff hs WSR handle, and you can also find us on Facebook at Facebook dot com slash tech Stuff h s W. For more on this and thousands of other topics, visit how Stuff Works dot com and be sure to check out the new tech Stuff blog now on the House Stuff Works homepage, brought to you by the reinvented two thousand twelve camera. It's ready, are you