Speaker 1: Brought to you by the reinvented two thousand twelve camera.
Speaker 1: It's ready. Are you get in touch with technology? With
Speaker 1: tech stuff from how stuff works dot com. Hey there,
Speaker 1: welcome to the podcast. My name is Chris Polette. I'm
Speaker 1: an editor here and How Stuff Works with me as
Speaker 1: writer Jonathan Strickland. Howdy and uh. We've been looking at
Speaker 1: some of the most popular articles on the site to
Speaker 1: get some ideas for podcasts, and today we decided on
Speaker 1: how l c D s work. That's liquid crystal displays.
Speaker 1: And the listeners to this podcast probably know what that means,
Speaker 1: but it might be looking at one right now in
Speaker 1: fact exactly UM, but a lot of people don't know
Speaker 1: exactly how they're made. I was one of those, UM,
Speaker 1: and I went back into uh the l c D
Speaker 1: article that we have on the site, and basically, it's, uh,
Speaker 1: the screen that you see on your laptop computer or
Speaker 1: your desktop display is a is a sandwich, as we
Speaker 1: say in the South. It's UM. It's got a mirror,
Speaker 1: it's got a couple of pieces of glass and in
Speaker 1: between it it had as uh something to collect that
Speaker 1: conducts electricity. UM. And the missing piece in this sandwich
Speaker 1: UM is not Bologney. It is a fan of liquid crystals. UM.
Speaker 1: The crystals themselves are sort of in between you might say,
Speaker 1: what is a liquid crystal. It's sort of in between
Speaker 1: a solid and a liquid UM. And the key is
Speaker 1: that uh conductor, the electricity that's behind it UM. These
Speaker 1: crystals are twisted UM and basically, depending on how much
Speaker 1: of an electrical charge they receive, the untwist to let
Speaker 1: more light through. And what you see when you look
Speaker 1: at the display is the light reflecting off that mirror
Speaker 1: behind the crystals, and they change to display a different picture,
Speaker 1: you know, depending on how much electricity red uses or
Speaker 1: white uses UM. And it's a you know, pretty simple thing,
Speaker 1: you know. They they're they're one of the big things
Speaker 1: right now is l c D s and televisions, l
Speaker 1: c d s and laptops and computers, right and that
Speaker 1: light is always on, which is why you hear people
Speaker 1: talk about l c d s and contrast with with
Speaker 1: with the blacks, because even when your screen is black,
Speaker 1: it's still back lit. So if you have an older
Speaker 1: l c D screen, it may not show blacks as
Speaker 1: well as some of the newer ones. Uh. If you
Speaker 1: were to to have your your computer on, but have
Speaker 1: a black screen, uh, and then turn off the lights.
Speaker 1: You would still be able to kind of see where
Speaker 1: the screen was, right. Yeah, it's sort of a dark gray,
Speaker 1: you know, the right gray, rather than a complete black
Speaker 1: like you might see with a plasma television. That's one
Speaker 1: of the deals that a lot of people who are
Speaker 1: plasma afficionados prefer. Yeah, right, right, and and but people
Speaker 1: also point out that l c D displays tend to
Speaker 1: be better as far as an energy consumption goes then plasma.
Speaker 1: That plasma actually takes up more energy to to warm
Speaker 1: up and keep running. Um, so you would think that
Speaker 1: l c D s are really the more green, anscious
Speaker 1: way to go if you're gonna buy electronics. But we
Speaker 1: just found out something that that kind of puts this
Speaker 1: into a different light. Yeah, I was, I was reading
Speaker 1: a story I think it was initially I've seen it
Speaker 1: in It's actually been in several places that Grist magazine,
Speaker 1: which is an environmental website. Um, you know, it's been
Speaker 1: in uh New Scientists, I believe, and it was an
Speaker 1: article that was based in the Geophysical Research Letters. It is,
Speaker 1: you know, it's on my coffee table unfortunately has filled
Speaker 1: coffee on it and wasn't able to read this article.
Speaker 1: But it's all about this chemical called nitrogen trifluoride, which
Speaker 1: is apparently not something you put on your teeth. No. No,
Speaker 1: Nitrogen trifluoride is a gas that's used in the production
Speaker 1: of l c d s. It's one of several gases
Speaker 1: that are used. Um. It's used in a thin film deposition.
Speaker 1: Now that's that's kind of not to get too technical,
Speaker 1: but you use a vapor to create a very thin
Speaker 1: film home which l c ds need in order to work. Um.
Speaker 1: And it's not just l c d s, they're they're
Speaker 1: used for things like semiconductors and other things as well. Uh.
Speaker 1: The problem is that nitrogen trifluorides a pretty nasty gas. Uh,
Speaker 1: not just hazardous to humans if you inhale it, although
Speaker 1: I don't recommend doing that. First of all, it's got
Speaker 1: a moldy odor, so it doesn't smell very good, and
Speaker 1: it can also poison your liver and kidneys, So if
Speaker 1: you if you're used to have in those, I would
Speaker 1: recommend not taking a big whiff of nitrogen trifluoride. But
Speaker 1: it also is environmentally hazardous. Turns out it's extremely environmentally hazardous. Yeah.
Speaker 1: Try seventeen thousand times more serious than carbon dioxide. That's
Speaker 1: a that's a big number. Yeah, it's a very big number. Um.
Speaker 1: The funny thing is this, uh, this was actually intended.
Speaker 1: This gas is actually replacing uh, chemicals called perfluora carbons,
Speaker 1: which are greenhouse gases. Um. And they removed those because
Speaker 1: of environmental concerns that they were contributing to global warming. Right,
Speaker 1: and and nitrogen trifluoride wasn't even on the Kyoto Protocols,
Speaker 1: you know, international Climate Change Agreement, that that wasn't listed,
Speaker 1: so it completely skipped under the radar. It wasn't until this, uh,
Speaker 1: this information in the geophysical research letters that people really
Speaker 1: started to pay attention and say, hey, this stuff is
Speaker 1: is serious business. That's true. Um. As it turns out,
Speaker 1: there was so little of it being made around the
Speaker 1: time of the the Kyoto Treaty writing you know, being
Speaker 1: written in the nineties that they just they really had
Speaker 1: no idea of the environmental impact of it. But apparently
Speaker 1: if you produced if you took all the uh n
Speaker 1: F three produced in two thousand and eight, according to
Speaker 1: the article, and released it in the atmosphere, it would
Speaker 1: have the same impact as the annual carbon dioxide emissions
Speaker 1: of Austria. Yep. That's UM family global warming, if you will.
Speaker 1: And just to give you a little more perspective, UM,
Speaker 1: there's initial projections for for nitrogen trifluoride production next year
Speaker 1: UM suggest that there will be around eight thousand metric
Speaker 1: tons of the stuff made in order to to make
Speaker 1: these various devices. UM. And then so this is eight
Speaker 1: thousand metric tons that eventually will enter the environment. And
Speaker 1: maybe years and years from now when people start throwing
Speaker 1: their their lc D displays away and they you know,
Speaker 1: rupture or whatever, it might be a while before this
Speaker 1: stuff actually makes it into the environment. But you multiply
Speaker 1: eight thousand metric tons by seventeen thousand times the strength
Speaker 1: of a carbon dioxide as far as a greenhouse gas goes,
Speaker 1: you end up with a hundred and thirty six million
Speaker 1: tons equivalent of carbon dioxide. It sounds like a lot,
Speaker 1: all right, I'm not gonna lie the hundred three or
Speaker 1: six million that's metric tons. That's that's a lot of tons.
Speaker 1: But in two thousand five, the United States produced nearly
Speaker 1: six billion metric tons of carbon dioxide from energy consumption.
Speaker 1: That's everything from coal firing to you know, everything as
Speaker 1: far as the energy production and consumption goes, including the
Speaker 1: energy that you would need to you know, say run
Speaker 1: your l c D devices exactly. So the six billion
Speaker 1: versus thirty six million, I mean, that's still you're talking
Speaker 1: about so many you know, orders of magnitude. But that
Speaker 1: doesn't mean that we should ignore this nitrogen tri fluoride problem.
Speaker 1: You know, that's just on my on my gut feeling here.
Speaker 1: I think it's sort of like the trans fat thing
Speaker 1: when it when it popped up, people all of a
Speaker 1: sudden went oh, well, uh, you know, I had no
Speaker 1: idea that was going on, and they you know, now
Speaker 1: that it's starting to you know, show up in the
Speaker 1: public consciousness, then now we're going to have to find
Speaker 1: some other solution that isn't you know, per flora carbons
Speaker 1: or something else to to make l c D s
Speaker 1: because you know, in the long run, the l c
Speaker 1: D is a is more is more energy efficient than
Speaker 1: a cathode ray tube or you know, some of the
Speaker 1: other devices that it is replacing, So you know, it's uh,
Speaker 1: it's a balancing. You're going to have to find some
Speaker 1: other solution to the other thing is that when you're
Speaker 1: looking at something like lc D displays that that seems
Speaker 1: like it's a much more manageable problem than reducing huge
Speaker 1: amounts of carbon dioxide emissions. It's at least something that
Speaker 1: we can take steps to to fix. You know, it's
Speaker 1: not a problem that's so huge that you just look
Speaker 1: at it and goggle and wonder what do I do?
Speaker 1: Although I good I should also point out this gas
Speaker 1: it's kind of ironic. Um it's also used in the
Speaker 1: production of photovoltaic cells also known as solar panels. So
Speaker 1: even when we're trying to be environmentally conscious and use
Speaker 1: renewable energy sources, we may be in the in the
Speaker 1: production of those sources, we might be doing some pretty
Speaker 1: severe damage to our environment. Yeah, well, I think that's
Speaker 1: probably enough depression for one podcast, don't you. Yeah, I'm
Speaker 1: I'm thoroughly worn out. Okay, Well, I'm sure guys are two.
Speaker 1: So if you would like to learn more about l
Speaker 1: c D s, read our article on how l c
Speaker 1: D S work at how stuff works dot com, and
Speaker 1: we'll talk to you again soon for more on this
Speaker 1: and thousands of other topics. Does it how stuff works
Speaker 1: dot com. Let us know what you think. Send an
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