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Speaker 1: Brought to you by the reinvented two thousand twelve camera.

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Speaker 1: It's ready. Are you get in touch with technology? With

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Speaker 1: tech stuff from how stuff works dot com. Hey there,

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Speaker 1: welcome to the podcast. My name is Chris Polette. I'm

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Speaker 1: an editor here and How Stuff Works with me as

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Speaker 1: writer Jonathan Strickland. Howdy and uh. We've been looking at

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Speaker 1: some of the most popular articles on the site to

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Speaker 1: get some ideas for podcasts, and today we decided on

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Speaker 1: how l c D s work. That's liquid crystal displays.

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Speaker 1: And the listeners to this podcast probably know what that means,

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Speaker 1: but it might be looking at one right now in

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Speaker 1: fact exactly UM, but a lot of people don't know

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Speaker 1: exactly how they're made. I was one of those, UM,

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Speaker 1: and I went back into uh the l c D

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Speaker 1: article that we have on the site, and basically, it's, uh,

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Speaker 1: the screen that you see on your laptop computer or

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Speaker 1: your desktop display is a is a sandwich, as we

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Speaker 1: say in the South. It's UM. It's got a mirror,

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Speaker 1: it's got a couple of pieces of glass and in

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Speaker 1: between it it had as uh something to collect that

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Speaker 1: conducts electricity. UM. And the missing piece in this sandwich

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Speaker 1: UM is not Bologney. It is a fan of liquid crystals. UM.

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Speaker 1: The crystals themselves are sort of in between you might say,

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Speaker 1: what is a liquid crystal. It's sort of in between

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Speaker 1: a solid and a liquid UM. And the key is

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Speaker 1: that uh conductor, the electricity that's behind it UM. These

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Speaker 1: crystals are twisted UM and basically, depending on how much

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Speaker 1: of an electrical charge they receive, the untwist to let

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Speaker 1: more light through. And what you see when you look

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Speaker 1: at the display is the light reflecting off that mirror

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Speaker 1: behind the crystals, and they change to display a different picture,

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Speaker 1: you know, depending on how much electricity red uses or

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Speaker 1: white uses UM. And it's a you know, pretty simple thing,

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Speaker 1: you know. They they're they're one of the big things

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Speaker 1: right now is l c D s and televisions, l

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Speaker 1: c d s and laptops and computers, right and that

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Speaker 1: light is always on, which is why you hear people

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Speaker 1: talk about l c d s and contrast with with

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Speaker 1: with the blacks, because even when your screen is black,

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Speaker 1: it's still back lit. So if you have an older

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Speaker 1: l c D screen, it may not show blacks as

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Speaker 1: well as some of the newer ones. Uh. If you

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Speaker 1: were to to have your your computer on, but have

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Speaker 1: a black screen, uh, and then turn off the lights.

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Speaker 1: You would still be able to kind of see where

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Speaker 1: the screen was, right. Yeah, it's sort of a dark gray,

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Speaker 1: you know, the right gray, rather than a complete black

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Speaker 1: like you might see with a plasma television. That's one

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Speaker 1: of the deals that a lot of people who are

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Speaker 1: plasma afficionados prefer. Yeah, right, right, and and but people

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Speaker 1: also point out that l c D displays tend to

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Speaker 1: be better as far as an energy consumption goes then plasma.

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Speaker 1: That plasma actually takes up more energy to to warm

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Speaker 1: up and keep running. Um, so you would think that

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Speaker 1: l c D s are really the more green, anscious

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Speaker 1: way to go if you're gonna buy electronics. But we

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Speaker 1: just found out something that that kind of puts this

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Speaker 1: into a different light. Yeah, I was, I was reading

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Speaker 1: a story I think it was initially I've seen it

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Speaker 1: in It's actually been in several places that Grist magazine,

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Speaker 1: which is an environmental website. Um, you know, it's been

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Speaker 1: in uh New Scientists, I believe, and it was an

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Speaker 1: article that was based in the Geophysical Research Letters. It is,

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Speaker 1: you know, it's on my coffee table unfortunately has filled

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Speaker 1: coffee on it and wasn't able to read this article.

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Speaker 1: But it's all about this chemical called nitrogen trifluoride, which

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Speaker 1: is apparently not something you put on your teeth. No. No,

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Speaker 1: Nitrogen trifluoride is a gas that's used in the production

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Speaker 1: of l c d s. It's one of several gases

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Speaker 1: that are used. Um. It's used in a thin film deposition.

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Speaker 1: Now that's that's kind of not to get too technical,

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Speaker 1: but you use a vapor to create a very thin

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Speaker 1: film home which l c ds need in order to work. Um.

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Speaker 1: And it's not just l c d s, they're they're

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Speaker 1: used for things like semiconductors and other things as well. Uh.

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Speaker 1: The problem is that nitrogen trifluorides a pretty nasty gas. Uh,

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Speaker 1: not just hazardous to humans if you inhale it, although

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Speaker 1: I don't recommend doing that. First of all, it's got

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Speaker 1: a moldy odor, so it doesn't smell very good, and

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Speaker 1: it can also poison your liver and kidneys, So if

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Speaker 1: you if you're used to have in those, I would

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Speaker 1: recommend not taking a big whiff of nitrogen trifluoride. But

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Speaker 1: it also is environmentally hazardous. Turns out it's extremely environmentally hazardous. Yeah.

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Speaker 1: Try seventeen thousand times more serious than carbon dioxide. That's

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Speaker 1: a that's a big number. Yeah, it's a very big number. Um.

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Speaker 1: The funny thing is this, uh, this was actually intended.

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Speaker 1: This gas is actually replacing uh, chemicals called perfluora carbons,

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Speaker 1: which are greenhouse gases. Um. And they removed those because

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Speaker 1: of environmental concerns that they were contributing to global warming. Right,

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Speaker 1: and and nitrogen trifluoride wasn't even on the Kyoto Protocols,

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Speaker 1: you know, international Climate Change Agreement, that that wasn't listed,

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Speaker 1: so it completely skipped under the radar. It wasn't until this, uh,

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Speaker 1: this information in the geophysical research letters that people really

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Speaker 1: started to pay attention and say, hey, this stuff is

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Speaker 1: is serious business. That's true. Um. As it turns out,

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Speaker 1: there was so little of it being made around the

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Speaker 1: time of the the Kyoto Treaty writing you know, being

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Speaker 1: written in the nineties that they just they really had

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Speaker 1: no idea of the environmental impact of it. But apparently

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Speaker 1: if you produced if you took all the uh n

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Speaker 1: F three produced in two thousand and eight, according to

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Speaker 1: the article, and released it in the atmosphere, it would

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Speaker 1: have the same impact as the annual carbon dioxide emissions

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Speaker 1: of Austria. Yep. That's UM family global warming, if you will.

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Speaker 1: And just to give you a little more perspective, UM,

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Speaker 1: there's initial projections for for nitrogen trifluoride production next year

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Speaker 1: UM suggest that there will be around eight thousand metric

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Speaker 1: tons of the stuff made in order to to make

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Speaker 1: these various devices. UM. And then so this is eight

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Speaker 1: thousand metric tons that eventually will enter the environment. And

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Speaker 1: maybe years and years from now when people start throwing

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Speaker 1: their their lc D displays away and they you know,

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Speaker 1: rupture or whatever, it might be a while before this

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Speaker 1: stuff actually makes it into the environment. But you multiply

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Speaker 1: eight thousand metric tons by seventeen thousand times the strength

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Speaker 1: of a carbon dioxide as far as a greenhouse gas goes,

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Speaker 1: you end up with a hundred and thirty six million

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Speaker 1: tons equivalent of carbon dioxide. It sounds like a lot,

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Speaker 1: all right, I'm not gonna lie the hundred three or

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Speaker 1: six million that's metric tons. That's that's a lot of tons.

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Speaker 1: But in two thousand five, the United States produced nearly

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Speaker 1: six billion metric tons of carbon dioxide from energy consumption.

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Speaker 1: That's everything from coal firing to you know, everything as

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Speaker 1: far as the energy production and consumption goes, including the

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Speaker 1: energy that you would need to you know, say run

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Speaker 1: your l c D devices exactly. So the six billion

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Speaker 1: versus thirty six million, I mean, that's still you're talking

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Speaker 1: about so many you know, orders of magnitude. But that

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Speaker 1: doesn't mean that we should ignore this nitrogen tri fluoride problem.

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Speaker 1: You know, that's just on my on my gut feeling here.

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Speaker 1: I think it's sort of like the trans fat thing

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Speaker 1: when it when it popped up, people all of a

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Speaker 1: sudden went oh, well, uh, you know, I had no

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Speaker 1: idea that was going on, and they you know, now

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Speaker 1: that it's starting to you know, show up in the

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Speaker 1: public consciousness, then now we're going to have to find

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Speaker 1: some other solution that isn't you know, per flora carbons

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Speaker 1: or something else to to make l c D s

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Speaker 1: because you know, in the long run, the l c

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Speaker 1: D is a is more is more energy efficient than

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Speaker 1: a cathode ray tube or you know, some of the

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Speaker 1: other devices that it is replacing, So you know, it's uh,

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Speaker 1: it's a balancing. You're going to have to find some

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Speaker 1: other solution to the other thing is that when you're

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Speaker 1: looking at something like lc D displays that that seems

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Speaker 1: like it's a much more manageable problem than reducing huge

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Speaker 1: amounts of carbon dioxide emissions. It's at least something that

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Speaker 1: we can take steps to to fix. You know, it's

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Speaker 1: not a problem that's so huge that you just look

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Speaker 1: at it and goggle and wonder what do I do?

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Speaker 1: Although I good I should also point out this gas

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Speaker 1: it's kind of ironic. Um it's also used in the

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Speaker 1: production of photovoltaic cells also known as solar panels. So

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Speaker 1: even when we're trying to be environmentally conscious and use

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Speaker 1: renewable energy sources, we may be in the in the

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Speaker 1: production of those sources, we might be doing some pretty

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Speaker 1: severe damage to our environment. Yeah, well, I think that's

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Speaker 1: probably enough depression for one podcast, don't you. Yeah, I'm

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Speaker 1: I'm thoroughly worn out. Okay, Well, I'm sure guys are two.

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Speaker 1: So if you would like to learn more about l

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Speaker 1: c D s, read our article on how l c

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Speaker 1: D S work at how stuff works dot com, and

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Speaker 1: we'll talk to you again soon for more on this

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Speaker 1: and thousands of other topics. Does it how stuff works

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Speaker 1: dot com. Let us know what you think. Send an

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Speaker 1: email to podcasts at how stuff works dot com. Brought

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Speaker 1: to you by the reinvented two thousand twelve camera. It's ready,

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