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The power required to get this podcast into your ears was brought to you in part by wind, water, coal, gas, and a generous contribution from the old sky guy himself: The Sun! Head to to find out how you can help support SciShow Tangents, and see all the cool perks you’ll get in return, like bonus episodes and a monthly newsletter!A big thank you to Patreon subscribers Eclectic Bunny and Garth Riley for helping to make the show possible!Follow us on Twitter @SciShowTangents, where we’ll tweet out topics for upcoming episodes and you can ask the science couch questions! While you're at it, check out the Tangents crew on Twitter: Ceri: @ceriley Sam: @slamschultz Hank: @hankgreen[Fact Off]Power from cheese & mayo (biogas),well%20%5B5%2D7%5D for dams[Ask the Science Couch]Micro hydro power[Butt One More Thing]Pig poop ponds
[SciShow Tangents Intro theme music]


Hank: Hello and welcome to SciShow Tangents, it's the lightly competitive knowledge showcase! I am your host Hank Green, and joining me this week, as always, is science expert, Ceri Riley.


Ceri: Hello!


Hank: And our resident everyman, Sam Schultz.


Sam: Hello!


Hank: Before we started recording the podcast, it would be difficult to not mention the fact that Sam, uh, left us waiting while we watched his exterminator try and kill the bugs that have infested his home.


Sam: [Laughing] Wow. Okay. Wait a minute...


[Ceri and Hank laugh]


Ceri: Yeah, he was over there with all this gas, just, like, spraying around. And then now Sam's just sitting there in the same room where the bug man really just left an, uh—an arsenal of stuff.


Hank: Yeah, it's a lot of gas. We could—seeing him on the zoom call is a lot of gas, a lot of bugs, and Sam.


Sam: The gas will make me funnier!


Hank: That's—[laughs]. Everyone knows that! Ceri, how is your new home with regards to bugs?


Ceri: Oh, it's fine. I haven't felt like there's been a big bug problem. I thought there was a fruit fly infestation or fungus gnat in my plants, but turns out we just had rotting potatoes on the counter. So... uh...


[Hank and Sam laugh, and then Ceri joins in]


Hank: One time when I was in college, our—our apartment smelled really, really bad and we just sorta, like, lived that way for a long time. And then one day we decided to take out the recycling that had been piling up for, uh, over a month. And so it was just, uh, newspapers—literally because that's how old I am—it was mostly newspapers and magazines just piled up in a big pile. We were taking it out and in between two of the newspapers was a chicken breast.


Sam: [Pained and grossed out] Ooh! A raw one?


Ceri: [Laughing] Oh no.


Hank: A raw—a raw chicken breast.


Sam: That's the stinkiest thing of all.


Hank: We were—we were convinced it was just Pete. But no! It was a raw chicken—and nobody ever figured out who did it.


Ceri: Gross.


Hank: Anyway!


[Ceri, Hank, and Sam all laugh]


Ceri: I feel so much better about my potato situation now.


Hank: [Laughing] Every week here on Tangents, we get together to try to one-up, amaze, and delight each other with science facts while also trying to stay on topic. But sometimes we'll talk about chicken breast newspapers. Our panelists are playing for glory and—but also they're playing for Hank Bucks, which I will be awarding as we play. And at the end of the episode, one of them will be crowned the winner. Now, as always, we're going to introduce this week's topic with the traditional science poem... this week from Ceri.


[Science Poem theme music plays behind Hank saying "traditional science poem"]


Ceri: This is an ode to the power of power, not feats of strength or battles of might. The thrum from a drum making kilowatt-hours, to charge up a car or turn on a light, in exchange for some fuel that it does devour. Wars have been fought over gas, oil, or coal, those remnants of yore that can generate heat. But some set their sights on a greener goal, turbines towering on hills or panels paving a street. We hope with our souls to take more control. But the thing about power is power is fraught. Our technology needs it to hum, whirr, and beep. Yet at what cost? In this cycle we’re caught. And change, my dear friends, doesn’t come cheap. So we try our best to do what we can, making plan after plan and adhering to bans, to care for life beyond our lifespan and do a little better than when we began.


Hank: I mean, we're getting really good at this.


Sam: I think our poems are amazing now.


[Ceri and Sam laugh]


Hank: That was so good! I felt like—like Wordsworth was in the room!


Sam: [Inspired] Yes.


Hank: Okay, wonderful! I mean, gosh, so our topic for the day is power generation, which can be done in a lot of different ways. So I guess we shouldn't just focus on power plants, 'cause you can do it without a power plant, uh, which is extraordinarily important. And I guess mostly is focused on electricity. Can you make the case that there is power generation that does not involve electricity? Probably, whether that's just like grinding up a mill or something. But like, is that—is sort of that the vibe that we're going for, Ceri?


Ceri: Yeah, I think so. In the email that I received about this topic, it said, "like power plants, solar panels, anything like that." So, uh, most of what I directed my research towards was electricity generation.


Hank: So how do you get an electron to move?


Ceri: You know, I looked this up and I can say the words, but I think that...


[Ceri, Hank, and Sam all laugh]


Hank: Yeah, one of the things we try not to do is: we try not to explain things we don't understand here at SciShow and yet! [Laughs]


Ceri: And yet we keep covering topics that have to do with non-biological things, but that's okay. So, generally, I think a lot of power generators are electromagnetic in nature. So basically what that means is: there is a coil of wire that is static and it's called the stator. I found a term for that. And then something turns a rotor, which turns a shaft inside the center of the stator. Um, and so that's like what burning coal does... you turn the rotor. Flowing water and hydroelectric systems... you turn a rotor. Windmill spinning... you turn a rotor. And that turning action, there's like some sort of magnetic or electrical stuff going on in that rotor so that the magnetic field is changing around the wires. And that changing magnetic field causes the electrons to move in such a way that it creates a current. And then that current runs out the wire on the other side. And then you get into, like, alternating current and direct current, and depending on how you process that flow of electrons, you get different kinds of electricity. But that is the bare basics of it.


Hank: There is a thing that spins around and that spinning pushes electrons, and those electrons get pushed through your light bulb. And that is how electricity works. That is as far as I've, like, really gotten in terms of being able to explain this. Why spinning a magnet inside of a bunch of wires does this? I'm sorry. It turns out electricity and magnetism are the same thing. Am I ever going to really get that? I don't think so! But somebody does, and thank god for them. They're—the one that's different from that, really, is solar panels, which actually...physically, like, the photon comes in and it basically knocks an electron free somehow.


Ceri: Yes. They're made of semiconductors, and so they absorb the photons that are emitted by the sun and then somehow electrons are knocked free and then flow.


Hank: Yeah, and they fall down a hole.


Ceri: [Laughs] Yeah, it's like a gumball machine.


Hank: There's always—they talk about holes in semiconductors a lot. And I'm like, okay, so there's a hole, I get it. It falls into the hole. Good. That's all I need.


Sam: But otherwise you're just spinning stuff around, mostly. That's it?


Hank: It's almost all spinning stuff around, yeah.


Ceri: I think if—a solar panel is kind of like a battery that is charged by the Sun. There's like layers to it? And then those layers help guide the movement of electrons, so it's not just random. Like, that's what creates the metaphorical hole for them to fall down. I looked up the etymology of both power and generation, uh...[Laughs]. And those are—they're, I don't know—they're pretty basic. Like, the idea of powerful things or, like, leaders existed and so power kind of existed. And then generation just comes from the same root as gene, which is to, like, give birth or create offspring or things like that. So you're, like, generating more powerful things. Uh, but I really tried to dive into when we were using the word power, not to mean a powerful person, but to mean energy. And I couldn't find an exact answer to it. One online source that I was reading—the etymology dictionary that I refer to for all of these—said that power meaning "energy available for work" is from 1727. But it sounds like we first used the word power to refer to energy. So instead of calling something—like, energy is moving through a system, we said power was moving through a system. Because when I was looking at the history of the word energy and how physicists used it, then the ideas behind the concept of energy began forming at the end of the 17th century when the term was first used in English to refer to power. So my sense is that we used energy and power kind of interchangeably until a physicist was like, "We actually need equations to describe this because this is confusing."


Hank: And energy is going to be one thing and power is going to be another thing. And I've—luckily I've got two words because there's two things here. Oh gosh, power. It's very important! I can't believe that it works at all, which brings us to our first game of the show! Because power plants take up a lot of space and they inevitably interact with animals and that can be bad for the power station, but also for the animal. In 2016, for example, a raccoon accidentally knocked out power to 40,000 homes in Seattle after getting into a power station. The raccoon did not lose power; the raccoon lost its life. So to protect wildlife and humans alike, power stations and scientists have been developing different tools to prevent animals from invading. And so we are going to play This or That, where I'm going to present you with a, uh, tool or strategy designed to keep power stations and animals separate and not impacting each other. And you will have to guess what animal the tool was designed for. That's the game. Are you ready?


Ceri & Sam: Yes.


Hank: You'll get two to choose from. You don't have to just pick a random animal.


Ceri: [Laughs] That—that's good because otherwise there's too many small furry mammals and too many types of birds.


Hank: Yeah. Well, this first one isn't going to be about either of those things, 'cause these oceanic invaders have been known to shut down power plants all over the world, including stations in Scotland, Sweden, Israel, and the Philippines. To prevent these invasions from taking place, researchers have been working on a tracking tool that will model the path of the animal over the year and help the power plants predict future invasions. Which is it, is it jellyfish or is it eels?


Sam: Hmm.


Ceri: I was thinking barnacles until you said—said moving.


Sam: Yeah, I was gonna say mussels of some sort.


Ceri: Uh-huh.


Hank: Yeah, those are also important for power plants. That's a big problem for hydroelectric plants is—is mussels.


Ceri: I'm gonna say jellyfish because I just have the image from some nature documentary I was shown in elementary school of, like, something thinking that a plastic bag floating in the ocean was a jellyfish and eating it and being like, "this is what your plastic bags are doing to the environment." So I imagine jellyfish, if they were sucked into something, they would gum it up like a plastic bag.


Sam: I'm gonna go with eels, 'cause I think a jellyfish would just get pulped in the plant, no problem.


Hank: Well, in 1999, jellyfish were responsible for a massive power failure in the Philippines after they got sucked into a seawater intake of a power plant in Manila! The authorities later reported that they removed—Sam, maybe they pulped some of them—50 truckloads of jellyfish.


Ceri: What?!


Sam: Nooo! [Laughs]


Hank: They have also shut down power stations in a lot of places because their populations can increase really quickly, to the point where they're actually a fairly significant portion of the seawater.


Ceri: And jellyfish can't, like, control where they swim, right? They just kind of drift around?


Hank: That's true. They just—there's like, oh, there's a current headed this way, I don't know why. And they—they can, like, push themselves a little bit, but mostly they're planktonic, yeah.


Ceri: So they didn't even want to be sucked in!


Hank: They did not want to cause problems, but, uh, researchers announced in 2016 that they're working on a model of how jellyfish blooms travel over the course of a year, which would give power plants a warning tool to predict future invasions. All right. So Ceri has one point headed into Round Number Two! These animals are maybe unfairly considered to be a pest by many, but in a power station they're actually a potential safety hazard, which is why it might be weird to know that some power stations will actually feed these animals. That's weird. But it turns out that they put something in the food. Is it poison? No, it's not! It's birth control to limit the growth of the animals' population. What is it? Is it rats or is it pigeons?


Sam: Rude!


Hank: [Laughing and echoing Sam] Rude! I don't know, is it better than poison?


Ceri: I don't know! This is too much of a philosophical question.


Hank: [Laughs] Yeah, I guess it depends on—it depends on how you think about it. For sure.


Ceri: [Thinking too deeply about it] Yeah.


Sam: I think...those two animals seem so similar, but I feel like pigeons are easier to take care of. You just go [in a mean voice], "Oh! Get out of here!" And you know where they are, they're not really hiding. Rats are a little bit tougher. I'm going to go with rats.


Hank: Yeah, you think it's rats?


Ceri: I also think it's rats. I—I'm trying to guess an animal while you're explaining it. And, in my head, popped in rats. So I'm going to go with it.


Hank: Okay. Well, power stations are a great space for safety and warmth for pigeons.


Ceri & Sam: Ugh!


Hank: And so, like in cities, power plants have multiple strategies to deal with pigeons. They have nets, they have spikes, all with the aim to prevent fall hazards. So if the pigeon's, like, accidentally, like, pushed something over—like it, all with the aim to, uh, prevent fall hazards. So if pigeons actually pushed something over, it could land on someone, also just contamination issues from the poop. But pigeons are smart and they're very persistent. And that's why this birth control system called OvoControl has been developed. The feeders hold about 120 pounds of bait laced with birth control, because the goal isn't to rid the whole area of pigeons, that would just mean another flock would move in. So this way, they get to prevent, uh, the fall hazards of pigeons, making nests and eggs that—'cause they're terrible at nest building—that would then fall on people. And, uh—and I think that they just, like, poop less when there's fewer of them, because they're sort of trying to make the baby thing happening. So it keeps the population low without, uh, allowing a new population of pigeons to move in and starting to breed more.


Sam: Okay.


Hank: So you don't want to get rid of them completely! You would if you could, but you can't. So you just get rid of their ability to breed.


Sam: Alright, that's less rude than murdering them or something.


Hank: I suppose it is less rude than murdering them. All right, so we're headed into Round Three with the same score: Ceri has one point, Sam has none. Sometimes you just give into the animals, as is the case for this beloved beast that is drawn to the warmth coming from power plants. Their commitment to the area has led to the creation of sanctuaries around power plants to shelter this animal. Is it pandas or manatees?


Sam: [Thinking of their cuteness] Ohh! Warmth.


Ceri: [Intrigued] Ohh. They both seem so gentle.


Sam: Manatees live in, like, Florida. They're probably always warm, right?


Hank: It can get chilly.


Sam: How chilly?


Hank: I grew up in Florida, and there are times when you wouldn't want to, like, swim around in the ocean for sure.


Sam: Okay. Okay.


Ceri: I don't feel like I've heard pandas wanting, like, warmth or hugs. Like, they're just so slow. Sometimes they like playing in snow. Maybe after that they want a—like a panda equivalent of a hot chocolate, but I have not seen that. So I'm going to guess manatees. They seem like they would like cuddle more than a panda would like a cuddle.


Sam: Well, I know from SciShow that pandas, like, roll in horse poop to take warm up if it's too cold. Something like that.


Hank: Wow, okay.


Sam: You probably hosted that episode, Hank, so...


Hank: I forgot about it. [Laughs].


Sam: Uh, I'm gonna—I'm gonna stick with my guns and say pandas.


Hank: All right! Well, in 1986, Big Bend power station saw a surge in the number of manatees gathering at the station's discharge channel, which was full of warm water coming from the plant. And it is very important that manatees have a pretty specific range of temperatures that they like to live in. And when it gets too cold, they do seek out these warmer spots. Power plants discharge warmer water into the ocean. So other plants in Florida have also been able to serve as manatee sanctuaries, and this has actually helped increase the population of manatees. But, while that is an exciting success for manatee populations in the short term, it's not a great long-term success story because it relies on the existence of coal plants, which are being phased out, uh, because they are otherwise not great for the environment. And as power plants begin to switch over to other resources, scientists are trying to figure out how to help manatees and their search for warmer waters, wild!


Sam: Get 'em hot tubs.


Hank: They gotta make manatee hot tubs. I've actually been to one of these manatee sanctuaries by a power plant. And it's just like, wow, these guys are so happy. It was, like, always there. Uh, you know, they know where they're going to be, so they're able to keep boats away...


Sam: Oh, that's nice!


Hank: ...and it's been quite good. Well, that means that Ceri came out of that with two points and Sam with none. So he's got a—a steep hole to dig out of when we come back, uh, from our break, when it will be time for the Fact Off.


[A transitional snippet of the SciShow Tangents Intro theme music plays]


Hank: All right. Welcome back, everybody! Now it's time for the Fact Off.


[Fact Off theme music plays]


Hank: Our panelists have brought science facts to present to me in an attempt to blow my mind. After they have presented the facts, I will judge which one will become a TikTok next week...or tomorrow, I guess, as this comes out...and, uh, and then award an amount of Hank Bucks in any way I see fit to the winner. Who goes first? Well we're gonna decide that with a trivia question. Mandironwala bhuddi is a village in India located near the Ganges river. There are no power poles in the village and in recent years the government has been making a push toward solar power in the area. As of 2019, what percentage of homes in Mandironwala bhuddi are powered completely by solar?


Ceri: Oh dear. This is something that I would like to know more about. Eventually I would love to have solar panels on a house that I own and know more about electricity. But this has been a distant future goal for a long time of knowing things about electricity. So I'm just going to guess 51%.


Hank: 51%, they got more than half. What do you think Sam?


Sam: It's gotta be more than half or else...I don't know. It seems like it would have to be a really high number. So I'm going to guess, like, 80%.


Hank: 100% of homes are powered by solar power!


Ceri: Good job!


Hank: All right, Sam, that means that you get to decide who goes first.


Sam: I want Ceri to go first. I'm feeling deflated.


[Ceri and Hank laugh].


Hank: Awww.


Ceri: Well, I'll pump you right up with my fact.


Hank: [Startled] Oh my gosh.


Ceri: [Regretting this bit] You'll—you'll get the—you'll get the joke in a little bit, I think.


Hank & Sam: [Laughing] Oooh okay.


Ceri: Wink! So a big push in environmental sustainability efforts is using things more than once or more than one way, like steering away from single-use plastics or composting food scraps to make fertilizer. But a big problem is that this one-and-done mentality is kind of normalized. For example, like we've been talking about, some major ways we generate power involve harvesting a fuel source like coal or natural gas or oil and burning it up. However, there's a lot of research into how we can use bacteria to keep inedible organic waste from heading to landfills and instead harness it to replace some of those one-and-done fuels. And this is called a biogas system. So I was making the joke about the gas.


Sam: Uhh... I don't really...


Ceri: You can cut it all out.


[Hank and Sam laugh]


Sam: Nope! It's staying in.


Ceri: [Regretting this bit even more] Hate that for me. Uh.


[Ceri, Hank, and Sam all laugh]


Ceri: So biogas systems utilize bacteria that do anaerobic digestion, which means they munch on the wastes in an oxygen-free environment. There are three main steps: breaking everything down into simpler organic materials, called hydrolysis; turning those into organic acids, called acetogenesis; and then turning those into biogas, called methanogenesis. And biogas is just a mixture of methane, carbon dioxide, and some other gases. And the rest of the solids and liquids are just a goop called digestate, which can be useful for fertilizers. My brain immediately associates methane and carbon dioxide and other gases as bad in an environmental context because they're both greenhouse gases that trap heat in the atmosphere. But the reality is that harnessing biogas is preferable to letting all this stuff just decompose and release these gases directly into the atmosphere over time. So this is a way to capture these gases from the waste rather than just letting it go straight, unused into heating up the planet. And that's because natural gas is mostly methane. And so we can either burn biogas to generate power or separate out just the methane to create biomethane, which is also called renewable natural gas and replace natural gas in the already established power generation systems. Um, and this is already happening in some places like with animal poop on farms, agricultural wastes, or my favorite: weird food waste that people didn't know what to do with. So for example, in December 2016, Michigan State University in the U.S. found themselves with 2,500 gallons of bad goopy mayonnaise. And instead of throwing it out, they plopped it into a biogas system that powers farm areas nearby campus.


Hank & Sam: Oooh.


Ceri: Or there's a power plant in the French Alps, where Beaufort cheese is made, that uses all the whey to make around 2.8 million kilowatt-hours per year of energy, around enough to support a community of 1500 people. And this is still a very small fraction of power generation, but food waste is such a massive issue. Uh, some statistics, it seems like around 30% of the global food supply is wasted every year. So, uh, anything we can do to keep from just trashing it seems relatively better.


Hank: One of the hardest things to decarbonize is the existing natural gas infrastructure. So we have so much infrastructure in the U.S. and other places that is—how do you—like, getting methane into our homes so that we can burn it for hot water and for heat and in stoves. Stoves, you can replace that with an electric or other kind of stove, but hot water and heat are really hard to convert from. So the only ways you can change that is by finding some sort of carbon-neutral way to generate methane, and biogas is the—the main way. Hats off to people who are trying to make that work.


Ceri: Mhmm.


Hank: All right, Sam, what do you have for us?


Sam: Okay, here I go! Hydroelectric dams generate energy by basically blocking a river and funneling the water from the river past the turbine. The water spins the turbine and the energy of the water's movement is stored as electricity. Sure. But in order to harness that energy, the dam has to block up a river, and there are still fish that live in the river and those fish need to get past the dam so they can do the things that fish do. Uh, and in those dams—for a lot of them, the fish I think just kind of squeeze past the turbine—like, which can be dangerous, not great for them. Other dams have ways for fish to travel past the turbine in ways that don't involve them swimming past it and getting squished or bumped around or whatever, like pipes and fish ladders and things like that. But researchers in the Pacific Northwest were noticing that even in dams with safety precautions like pipes, uh, that fish could go through, about 10% of fish were still coming out of the dams dead or badly injured. So they hypothesized that the fish were just bumping into things and,, like flipping around and going nuts in there. But they didn't really have a way to figure out what was going on. I guess they couldn't, li put a camera on there and see what was going on, and they couldn't talk to the fish or anything like that. So they invented the sensor fish! So they're 3.5 inch long devices. They're about the size of a salmon smolt when they first make their trip from the river to the ocean. And they're perfectly balanced to float at the depth that salmon smolts swim. And they're filled with sensors that allow them to take 2000 measurements per second. And they're designed to be sent through a dam, take measurements during their trip, come out the other side, then there's like a balloon on a timer that inflates, so then you can just scoop 'em up!


[Hank laughs]


Sam: Scientists, uh, were mostly interested in the jostles and rotations that fish were making in the dams, but the sensor fish had a barometer in them, and that is what revealed an unexpected culprit of fish harm: sudden pressure changes. So as water travels through dams, it makes a pretty big drop, which is how it gets going, I guess, to spin the turbine. And that drop, plus all the turbulence of things spinning around and stuff like that, can cause sudden changes in water pressure that the fish aren't—they don't see coming. And this can damage a fish's internal organs, including its swim bladder, which inflates and deflates in response to pressure changes. So sudden changes in pressure can cause the swim bladder to expand rapidly, basically like a car airbag, which can, like, fuck 'em up inside, I guess. Put a lot of—of, like, air into their blood and damage their other internal organs and stuff like that. And the pressure changes of this—of going through a dam, some dams have been compared to the pressure change that a human would feel if they got into an elevator at the base of Mount Everest and went to the peak of Mount Everest in the blink of an eye. So that seems like it would mess you up pretty bad! And it messes up their swim bladders pretty bad. So sensor fish are helping engineers design dams that create less turbulence or have more gradual pressure changes, mostly with, like, different types of propellers on turbines and stuff like that. And sensor fish technology is also starting to be used worldwide, where it's helping to protect fish in countries like Germany, where hydroelectric dams are required by the government to perform live fish safety tests. So now they don't have to do that as much anymore, I guess, but it's probably way more expensive 'cause they're like $4,000 a sensor fish or something like that. Might as well just go get some fish.


Hank: [Laughing] Well, as you said, you cannot have, like, a post-interview with a fish... bring it into the room with a light on its head and be, like, "What did you go through?! Tell me about the barometric pressure you experienced!?!"


Sam: I don't know why you'd have to be so rude to 'em.


Hank: I don't know. [Stuttering]. Good cop, bad cop!


Ceri: Yeah. You're good cop, Sam.


Hank: Yeah.


Sam: I put the little like, uh—the little foily blanket on them and be like...


Hank: You put the foily blanket on them. You're like, "You want some fries? You want—I'm going to In-and-Out, you want me to pick something up?" And then while you're gone, I'm like [pounds table], "Look, now that Sam's gone, you're going to tell me all about what your acceleration rates. How much did you bump!? Tell me about your bumps!!!"


[Ceri and Sam laugh].


Hank: Uh, so—so we've got, uh, mayonnaise used to generate electricity using biogas generated by bacteria from Ceri, or electro fish...what are they called? Sensor fish? That have figured out that rapidly expanding swim bladders were harming fish inside hydroelectric dams, a thing that we didn't know and needed to know. Iiiiiiiii..... think that the winner of this is the sensor fish. You know, and thinking of it in—in terms of the—of, of a TikTok. Mayonnaise power, it's a better headline, I think. But it's—you know, it's like, it is in the frame of stuff that I already knew quite a lot about. Maybe I'm different in that because I spend so much time thinking about green energy. But sensor fish, I don't know! Especially with their little balloons, the fact that they got balloons...


Sam: The balloons are pretty cute.


Hank: Yeah. Alright, uh, well you had a two Hank Buck deficit to overcome, Sam.


Sam: Yeah.


Hank: And I'm going to give it to you! I'm gonna say that your sensor fish—uh, Ceri, I can see Ceri feeling a little bit slighted there!


Ceri: [Slighted for sure] Yeah! I did so good at that game, but the sensor fish...I'm going to look one up so that I can feel better about my loss.


Hank: They don't look as cool as you are imagining. So congratulations Sam on your win! And that means it's time to Ask the Science Couch, where we've got listener questions for our couch of finely honed scientific minds.


[Ask the Science Couch theme music plays]


Hank: This question is from @BeanedictC: Could we generate power for mini hydroelectric dams in rain gutters? I mean, theoretically, yeah. Uh, I think that there are a couple of problems with this idea. Should I hit you with them Ceri? Or should you tell me about them?


Ceri: You should do this—This is, like, a topic that you do know a lot about that I don't know a lot about, so...


Hank: Well, I know both about energy generation and about gutters because I have them and I have to clean them. And so my main—my main con—worry here is that you want your gutter to be clean, and like a real, real smooth slide all the way down because stuff gets in there. And you can't, like, prevent stuff from getting in there. There are a couple of ways that people have sort of experimented with how to, like, prevent the leaves and the detritus of the world from getting in the gutters. But for the most part, unless you can get rid of that, I don't really see it happening. The other concern here, uh, would be that it's probably not as much power as you might be thinking. The sort of like—a roof...a roof's worth of water, traveling down a roof's worth of height. Now that might not be the case for a really tall building. Um, so maybe like a skyscraper could...could generate a significant amount of power that way. Basically, you can imagine a hydroelectric plant, not as like water traveling downward, but as the weight of the water that is sitting on top of the water, pushing the water at the bottom through something. It's that weight of water that—that can not just turn a turbine, but like turn it a lot. And it really fast with a lot of energy. So that difference between the height of the water and the, you know, the amount of sort of pressure that's built up on top of the water that's getting squeezed out of a hole at the bottom is what you're—what you're concerned about. So you need a lot of—you need a lot of water stacked up in your gutter to turn a turbine. And I don't know that you'd get a ton. But also my main concern is stuff getting stuck in it. And you always gotta clean out your gutters. You gotta sometimes shove a hose up there to get it, all that stuff—all those leaves that are packed up in the downspout out, and you don't want something in there blocking anything up any more than it already is.


Sam: Right.


Ceri: That's basically what I found too, is that, um, people are looking into what's called micro hydroelectric power systems. So that's anywhere from generating five to 100 kilowatts, but mostly in rivers or streams. For all the reasons that you were explaining, where a lot of the structures that we build to collect water are not regular enough to—to make it worth it. Like material costs, maintenance costs, or, like, even the power generation and needing to siphon it off to a home that exists. Like, would it be worth it for everyone to have their own, like, gutter based mini hydroelectric system? Even though like, that idea sounds very cool and modern and, like, the revolution, like, could happen. Uh, but—but like practically it...there are too many limitations with how, um, even micro hydroelectric power systems work and need to be set up and maintained for that to be a great idea.


Hank: Yeah. I think a lot of micro-hydro is—or at least last time I paid attention to it—it was largely for people who lived far away from electricity infrastructure who could generate power that way. If it's hard to do solar, or it's hard to do other things, you could, you know—If you live in, like, dense forests with a lot of water, you can generate power that way and...and be able to have lights and laptops and stuff, even if you're way off the grid.


Ceri: What I learned today was I didn't need to work as hard as I did for this episode, because this is not my area of expertise. And I worked really hard to do it, but I should have just remembered that Hank knows everything.


Hank: Well, if you want to Ask the Science Couch your question, follow us on Twitter @SciShowTangents, where we'll tweet out topics for upcoming episodes every week. Thank you to @JeffroDotVT, @mooklepticon, and everybody else who tweeted us your questions for this episode.


[SciShow Tangents Outro theme music plays under Hank speaking]


Hank: If you like SciShow Tangents, don't you feel compelled to help us out in some way? 'cause like, oh, it's such a good podcast... I'd like to help them out! Well, here's some ways you can do that. You can become a, because that will get you access to things like our bonus episodes and our newsletter. Our bonus episodes are stupid fun! I don't want to say they're any better than our normal episodes, but they're pretty good!


Sam: Uh, also we're less than a hundred away from our Cars 2: Time Travel Mater, uh, commentary.


Hank: Wow. We're still creeping up!


Sam: We're almost at 420 too! [Makes a little cool guy ehhhh noise]


Hank: [Laughing] Okay. Sam's really excited to get to 420. Uh, when we get to 420, Sam and I will nod do each other and go ehhhh [mimicking what Sam just did] and that's it.


[Sam laughs]


Hank: Uh, you can also leave us a review wherever you listen. That's very helpful and it helps us know what you like about the show. Finally, if you want to show your love for SciShow Tangents, just...


Ceri, Hank, & Sam: Tell people about us!


Hank: Thank you for joining us. I've been Hank Green...


Ceri: I've been Ceri Riley...


Sam: And I've been Sam Schultz.


Hank: SciShow Tangents is created by all of us and produced by Caitlin Hofmeister and Sam Schultz who edits a lot of these episodes along with Hiroka Matsushima. Our social media organizer is Paola Garcia-Prieto. Our editorial assistant is Deboki Chakravarti. Our sound design is by Joseph "Tuna" Metesh. And we couldn't make any of this without our patrons on Patreon. Thank you, and remember: "the mind is not a vessel to be filled, but a fire to be lighted."


[SciShow Tangents Outro theme]


Hank: But! One more thing!


[Butt One More Thing theme]


Hank: In North Caroliney. [Startled and laughing at what just came out of his mouth] North Caroliney?!


Sam: [In exaggerated Southern drawl] North Caroliney! Woohoo!


Hank: [Laughing] The, uh, the pork industry, uh, and the energy industry have teamed up on what they hope will be the next great source of energy: giant pools of pig poop. The ponds are called lagoons and they're full of pig manure and bacteria, uh, that comes out of the—the areas where the pigs live. Uh, they're unpleasant places as you would imagine, but, uh, they digest the manure—the bacteria—and they release gases. And the lagoon is covered by a piece of black plastic and that traps the gas inside so it can be transported to a station to remove the water vapor and carbon dioxide. And that leaves behind pure methane that can be burned in a gas-fired home furnace or an electric power plant. While this process is considered a zero carbon fuel because it prevents greenhouse emissions, some people in the world are not a huge fan of it because of the smell and also the possibility of the lagoons, uh, flooding during hurricanes, which then creates a giant toxic mess that you can't really clean up. Uh, also in general, we are probably in the next hundred years just gonna move a little bit away from the entire institution of the live animal food products. Uh, one step at a time, one step at a time.


Sam: Are you pretty confident about that?


Hank: I'm pretty confident about that. You know, I think that, I think that people a hundred years from now will still be eating meat. I think that, uh, almost all of it will not come from live animals. But some of it will because some people will pay a lot of money for a unique experience. Even if that is intrinsically tied to suffering.


Sam: Hilarious!


[Ceri, Hank, and Sam all laugh]