WEBVTT - How Hydroelectricity Works 0:00:04.480 --> 0:00:12.360 Welcome to tech Stuff, a production from iHeartRadio. Hey there, 0:00:12.400 --> 0:00:15.800 and welcome to tech Stuff. I'm your host, jonvan Strickland. 0:00:15.800 --> 0:00:19.439 I'm an executive producer with iHeart Podcasts and how the 0:00:19.480 --> 0:00:23.640 tech are you? So Here in the Southeastern United States, 0:00:23.960 --> 0:00:30.000 a hurricane called Helene has caused catastrophic damage with tragically 0:00:30.120 --> 0:00:34.600 deadly consequences. We here in Atlanta, we were only grazed 0:00:35.080 --> 0:00:38.559 by it. The storm passed largely to our east. But 0:00:38.640 --> 0:00:42.440 even as Helene transformed from hurricane to tropical storm, it 0:00:42.640 --> 0:00:48.839 caused lots of problems, particularly in eastern Tennessee and western 0:00:48.920 --> 0:00:53.600 North Carolina. At one point there were reports that said 0:00:53.760 --> 0:00:59.360 the Walters Dam, also known as the Waterville Dam, had failed. 0:00:59.760 --> 0:01:03.160 While dam is on the Pigeon River at one end 0:01:03.280 --> 0:01:07.920 of Waterville Lake, and it is a hydro electric dam. 0:01:08.200 --> 0:01:11.199 So today I thought I would talk about how hydro 0:01:11.360 --> 0:01:14.440 electric dams work while sending lots of love to the 0:01:14.480 --> 0:01:17.520 folks in western North Carolina and up in Tennessee who 0:01:17.560 --> 0:01:22.679 continue to endure dangerous and difficult circumstances. If any of 0:01:22.720 --> 0:01:25.280 y'all are out that way, please please try and be 0:01:25.319 --> 0:01:28.680 as safe and careful as possible. Fortunately, the reports of 0:01:28.800 --> 0:01:32.160 the dam failing. It turned out to be false, but 0:01:32.280 --> 0:01:35.600 it also meant that people were urged to evacuate, which 0:01:35.640 --> 0:01:39.440 was probably a good thing considering the massive flooding conditions 0:01:39.440 --> 0:01:43.840 that have persisted in those areas. So let's talk about 0:01:44.040 --> 0:01:47.400 hydro electric dams. And there are quite a few things 0:01:47.440 --> 0:01:49.520 we need to talk about before we even get to 0:01:50.240 --> 0:01:54.279 hydro electric dams. One of those our use of water 0:01:54.360 --> 0:01:57.640 power in order to do work that's been going on 0:01:58.000 --> 0:02:01.840 for more than a millennium. The Greeks invented a water 0:02:01.880 --> 0:02:06.080 wheel for doing stuff like milling grain, and early reference 0:02:06.160 --> 0:02:10.000 can actually be found in the works of Philo of Byzantium, 0:02:10.280 --> 0:02:14.440 who lived between two eighty BCE and two twenty BCE. 0:02:14.800 --> 0:02:16.919 It is probably wondering why the heck they were counting 0:02:16.919 --> 0:02:21.520 backwards with their years, that's a joke. Similar engineering was 0:02:21.560 --> 0:02:25.560 going on in China, so it wasn't just the Greeks 0:02:25.560 --> 0:02:28.280 who had thought this up. Chinese engineers had come up 0:02:28.320 --> 0:02:33.920 with similar approaches. So this was kind of spun not spontaneously, 0:02:33.960 --> 0:02:37.320 that's giving the wrong word, but emerging in different parts 0:02:37.360 --> 0:02:40.639 of the world around the same time period. And folks 0:02:40.639 --> 0:02:42.880 had figured out that the flow of water was a 0:02:42.919 --> 0:02:46.880 really good source of work power if you could harness 0:02:47.040 --> 0:02:50.840 that water properly, and water wheels were the way to go. 0:02:51.320 --> 0:02:54.880 This early work would evolve over time, with mills and 0:02:54.919 --> 0:02:59.320 such becoming much more complex over the following centuries, but 0:02:59.760 --> 0:03:02.840 that it's an important thing to start with, this idea 0:03:02.919 --> 0:03:06.840 of harnessing the power of moving water. You typically would 0:03:06.840 --> 0:03:10.280 have a wheel outfitted with blades. The water would make 0:03:10.400 --> 0:03:14.400 contact with those blades, pushing the wheel to rotate, and 0:03:14.440 --> 0:03:19.080 you would use that rotational energy to operate something like 0:03:19.600 --> 0:03:22.959 the grindstone for a mill, so you could grind grain 0:03:23.120 --> 0:03:26.080 down into flour, that kind of thing. That wasn't the 0:03:26.080 --> 0:03:29.000 only application, but it was a common one. So that 0:03:29.160 --> 0:03:33.160 sets the stage for part of our equation. Now let's 0:03:33.240 --> 0:03:37.000 skip way ahead to the early to mid seventeen hundreds, 0:03:37.280 --> 0:03:40.240 so more than a millennia has passed at this point 0:03:40.440 --> 0:03:45.560 from the original water wheels. In the mid seventeen hundreds, 0:03:45.600 --> 0:03:50.400 a French engineer named Bernard Forrest de Belldor wrote an 0:03:50.480 --> 0:03:55.920 exhaustive treatment on hydraulics, and it was titled Architecture hydra Leik. 0:03:56.320 --> 0:03:59.920 It was published in four volumes starting in seventeen thirty seven, 0:04:00.320 --> 0:04:03.480 with the fourth one, publishing in seventeen fifty three. His 0:04:03.600 --> 0:04:07.320 work would help inform countless other engineers who are working 0:04:07.360 --> 0:04:11.520 on things like waterways and water works that sort of stuff. 0:04:11.600 --> 0:04:15.520 Because Old Bernie he was primarily a military and civic engineer. 0:04:15.720 --> 0:04:20.039 Much of his work focused on military operations, which obviously 0:04:20.160 --> 0:04:24.720 require a lot of versatility and resilience. I mean, if 0:04:24.720 --> 0:04:26.480 you're going to make stuff for the military, it has 0:04:26.520 --> 0:04:28.920 to be able to withstand a lot of punishment. And 0:04:29.000 --> 0:04:32.719 his work actually helped set the foundation for the Industrial Revolution. 0:04:32.839 --> 0:04:35.960 It guided a lot of mechanical engineers in the eighteenth 0:04:36.000 --> 0:04:39.960 and nineteenth centuries. Now we'll do another short hop to 0:04:40.040 --> 0:04:43.839 the end of the eighteenth century. That's when Michael Faraday 0:04:43.960 --> 0:04:47.320 was born. He was born in England on September twenty second, 0:04:47.640 --> 0:04:50.919 seventeen ninety one. This was about thirty years after Old 0:04:51.040 --> 0:04:54.840 Bernie had shuffled off the mortal coil. Faraday grew up 0:04:54.839 --> 0:04:58.720 to be a very very clever, smarty pants. Initially he 0:04:58.920 --> 0:05:02.040 was a chemist and a darned good one, but he 0:05:02.080 --> 0:05:06.400 also did pioneering work in the fields of magnetism and electricity, 0:05:06.640 --> 0:05:10.159 sometimes literally as and he literally did work in magnetic 0:05:10.160 --> 0:05:14.360 and electrical fields because I'm clever, and it was Faraday 0:05:14.640 --> 0:05:19.120 who proved there was a relationship between magnetism and electricity. 0:05:19.440 --> 0:05:23.200 If you were to move a permanent magnet near an 0:05:23.240 --> 0:05:29.480 electrical conductor, then you would induce voltage. You would induce 0:05:29.640 --> 0:05:33.600 an electric current to flow through that conductive material. The 0:05:33.640 --> 0:05:37.400 magnetism was what was doing it, but it only happened 0:05:37.680 --> 0:05:42.080 as a conductor moved through a magnetic field. If you 0:05:42.240 --> 0:05:46.760 just put a permanent magnet, even a really strong permanent magnet, 0:05:47.160 --> 0:05:53.000 next to a conductor, then once that initial fluctuation settled, 0:05:53.080 --> 0:05:56.239 you would not have an electrical charge. It just wouldn't 0:05:56.240 --> 0:05:59.360 be flowing. However, if you did keep the magnet moving 0:05:59.400 --> 0:06:04.359 around the or you move to conductor around a magnet, voila, 0:06:04.880 --> 0:06:08.680 you would start to detect an electrical charge. Thus, Faraday 0:06:08.760 --> 0:06:12.760 learned that a fluctuating magnetic field can induce electricity to 0:06:12.760 --> 0:06:16.279 flow through a conductive material. This allowed for the creation 0:06:16.520 --> 0:06:21.040 of both electric motors, which use an electric charge and 0:06:21.120 --> 0:06:26.680 magnetism to convert that into physical work, and the dynamo, 0:06:27.040 --> 0:06:31.000 which does the inverse. You do physical work and you 0:06:31.160 --> 0:06:36.240 use magnetism and you generate electricity through the process. Essentially 0:06:36.600 --> 0:06:39.080 the way This works is you start with a permanent 0:06:39.120 --> 0:06:43.040 magnet and you use this permanent magnet to essentially surround 0:06:43.200 --> 0:06:46.240 a loop of wire in the magnetic field. The loop 0:06:46.279 --> 0:06:48.839 of wire you would mount on an axle that you 0:06:48.839 --> 0:06:52.400 could rotate, and the ends of the wire themselves they 0:06:52.440 --> 0:06:55.280 would connect to what are called slip rings, one each, 0:06:55.520 --> 0:06:58.000 So one end of the loop is on one slippering, 0:06:58.240 --> 0:06:59.920 the other end of the loop is on another slipper, 0:07:00.200 --> 0:07:03.360 both of which are around this axle that rotates. So 0:07:03.880 --> 0:07:07.000 then imagine that you have connecting to the slooper rings 0:07:07.200 --> 0:07:11.120 brushes that in turn connect to electrical wires. So the 0:07:11.160 --> 0:07:14.960 brushes can conduct electricity as well. They just rest against 0:07:15.160 --> 0:07:18.800 the slip ring. So those electrical wires then connect to 0:07:18.840 --> 0:07:21.560 a circuit. Let's say that our circuit connects to a 0:07:21.640 --> 0:07:25.240 light bulb. It's a really simple electrical circuit. So one 0:07:25.360 --> 0:07:28.679 end connects to the slipperings that in turn are connected 0:07:28.720 --> 0:07:32.000 to either end of a loop inside this permanent magnet, 0:07:32.200 --> 0:07:36.520 and the other ends connect to the electrodes on a 0:07:36.600 --> 0:07:41.120 light bulb. So rotating this loop of wire inside the 0:07:41.120 --> 0:07:45.600 permanent magnet means that the loop is going through the 0:07:45.640 --> 0:07:48.960 magnet's magnetic field. And that is the same as having 0:07:49.000 --> 0:07:53.440 a fluctuating magnetic field. So it induces an electrical charge 0:07:53.680 --> 0:07:56.440 to flow in the loop, and electricity flows through the 0:07:56.480 --> 0:07:59.560 slipp rings, through the brushes to the wires, and you 0:07:59.560 --> 0:08:02.400 have yourself a simple electrical generator. So in this case, 0:08:02.400 --> 0:08:04.640 the generator is connected to the light bulb and it 0:08:04.720 --> 0:08:07.360 lights up as current is supplied to it. Now, this 0:08:07.440 --> 0:08:13.520 particular arrangement would be an AC generator alternating current. Now 0:08:13.560 --> 0:08:17.160 to understand why, let's think of those two wires that 0:08:17.240 --> 0:08:20.720 we have connected to either ends of the loop through 0:08:20.800 --> 0:08:24.880 these brushes and slipperings. Right, So one wire connected to 0:08:24.920 --> 0:08:27.640 the light bulb to the slippering is wire A. The 0:08:27.720 --> 0:08:31.440 other one we'll call wire B. So wire A effectively 0:08:31.600 --> 0:08:36.280 is connected to one end of this loop, and wire 0:08:36.320 --> 0:08:38.839 B is connected to the other end of the loop. Now, 0:08:39.360 --> 0:08:42.000 imagine we've got this loop of wire nestled between the 0:08:42.000 --> 0:08:45.559 north and south poles of a magnet, and we've frozen time. 0:08:45.640 --> 0:08:48.240 At the moment, it is in rotation, but we've frozen time, 0:08:48.280 --> 0:08:51.840 so everything's frozen, and right now the loop is horizontal 0:08:51.880 --> 0:08:54.200 in reference to the magnets on either side, so it's 0:08:54.240 --> 0:08:56.959 at a ninety degree angle to the magnetic fields. That's 0:08:57.000 --> 0:09:00.640 when the magnetic field is strongest, at least it's most 0:09:00.760 --> 0:09:04.240 strongly affecting the loop. The A side of our loop 0:09:04.520 --> 0:09:06.440 is closest to the north pole of the magnet. The 0:09:06.480 --> 0:09:08.559 B side of our loop is closest to the south pole, 0:09:08.920 --> 0:09:13.400 and we rotate so that side A is moving upward 0:09:13.559 --> 0:09:16.880 with reference to the magnet. Side B is moving downward 0:09:17.520 --> 0:09:21.200 because it's rotating right now. When the loop is vertical 0:09:21.400 --> 0:09:24.040 with reference to the permanent magnet, then we're at the 0:09:24.040 --> 0:09:27.719 weakest point with reference to the magnetic field. But the 0:09:27.800 --> 0:09:32.800 rotation continues. Now side A is moving downward in reference 0:09:32.840 --> 0:09:35.600 to the magnet and the south pole, and side B 0:09:36.000 --> 0:09:39.000 is moving upward toward the north pole. The flow of 0:09:39.000 --> 0:09:44.880 electricity then reverses direction. So every half rotation this happens 0:09:45.240 --> 0:09:48.920 right so as as side A is moving up, electricity 0:09:48.960 --> 0:09:51.880 flows in one direction. As side A starts to move down. 0:09:52.040 --> 0:09:55.200 Once it's completed that half rotation, electricity moves in the 0:09:55.240 --> 0:09:58.720 opposite direction. It is an alternating current, and this happens 0:09:59.120 --> 0:10:03.439 over an over again, So that is a type of 0:10:03.480 --> 0:10:06.800 alternating current. We're going to take a quick break. When 0:10:06.840 --> 0:10:09.800 we come back, I will talk about what you would 0:10:09.840 --> 0:10:12.560 do if you wanted to create a generator that created 0:10:12.720 --> 0:10:26.720 direct current. But first let's take this quick break. Okay, 0:10:26.880 --> 0:10:30.280 So we talked about an alternating current generator, a dynamo 0:10:30.640 --> 0:10:33.320 if you will, how do you create direct current where 0:10:33.360 --> 0:10:37.400 the direction of current remains consistent it doesn't change. Well, 0:10:37.559 --> 0:10:41.600 A lot of smaller electrical generators use this to create 0:10:41.679 --> 0:10:45.400 direct current. It's great for powering lots of devices that 0:10:45.480 --> 0:10:49.720 require direct current. It's not so great for transmitting power 0:10:49.760 --> 0:10:53.120 across great distances. You really need alternating current for that 0:10:53.559 --> 0:10:55.120 if you want to do it without a lot of 0:10:55.160 --> 0:10:58.400 electricity loss along the way, But we'll talk about that 0:10:58.440 --> 0:11:01.760 in a second. So you do this with a device 0:11:02.000 --> 0:11:07.000 called a commutator. That's the important component in a direct 0:11:07.000 --> 0:11:11.640 current generator, and essentially it's a special kind of segmented 0:11:12.040 --> 0:11:16.600 collar that goes around this rotating axle, and the segments 0:11:16.640 --> 0:11:21.280 are insulated from each other, so you can think of 0:11:21.320 --> 0:11:26.320 there being a gap in this collar that separates one 0:11:26.360 --> 0:11:31.800 side from the other. The commutator essentially reverses the reversal. 0:11:32.360 --> 0:11:36.400 So the wires connect to the commutator via brushes, and 0:11:36.440 --> 0:11:38.960 because of the break in the collar, it's almost like 0:11:39.000 --> 0:11:42.240 the wires are switching which side of the loop they're 0:11:42.240 --> 0:11:45.240 connected to. Remember before I was saying wire A and 0:11:45.360 --> 0:11:48.720 wire B to say like wire A is always connected 0:11:48.720 --> 0:11:52.160 to one side of our rotating loop and wire B 0:11:52.320 --> 0:11:54.880 is connected to the other side. But with a commutator, 0:11:55.400 --> 0:11:59.440 technically the wires are switching which side of the loop 0:11:59.480 --> 0:12:03.400 they're connected to with every half rotation. So because the 0:12:03.400 --> 0:12:08.959 wires are effectively swapping electrodes, the actual flow of electricity 0:12:09.040 --> 0:12:12.520 remains in the same direction the whole time. I know 0:12:12.640 --> 0:12:15.640 this is really tricky. It's tricky for me to explain. 0:12:15.760 --> 0:12:20.480 It's tricky to understand without the use of visual aids. 0:12:20.640 --> 0:12:22.880 I highly recommend that if you want to learn more 0:12:22.880 --> 0:12:26.439 about this, just go to YouTube and search how commutators 0:12:26.520 --> 0:12:31.079 work or how direct current generators work. That'll clear stuff 0:12:31.120 --> 0:12:33.080 up because you'll be able to see an illustration and 0:12:33.160 --> 0:12:35.960 understand what I'm talking about here. But it is a 0:12:36.040 --> 0:12:40.600 very clever workaround, Like you're still technically generating alternating current 0:12:40.679 --> 0:12:43.080 if you were just looking at the loop itself, but 0:12:43.200 --> 0:12:46.559 because of this commutator, you end up with direct current 0:12:46.640 --> 0:12:50.000 as your output. The important thing for our discussion is 0:12:50.000 --> 0:12:53.760 that using a coil of conductive wire. Material moving through 0:12:53.800 --> 0:12:57.000 a magnetic field induces electricity to flow. So if you 0:12:57.040 --> 0:12:59.880 have access to a source of physical power so that 0:13:00.400 --> 0:13:03.920 you can rotate this loop of wire, then you can 0:13:03.960 --> 0:13:07.640 generate electricity without expending a lot of effort yourself. Now 0:13:07.679 --> 0:13:11.400 you can have this connected to something like a crank 0:13:11.559 --> 0:13:15.240 or whatever that you physically turn and generate electricity that way. 0:13:15.320 --> 0:13:18.400 I actually have an emergency radio that works in this principle. 0:13:18.480 --> 0:13:22.120 You can crank the radio and it will generate enough 0:13:22.120 --> 0:13:24.760 electricity to power the radio. So if you are in 0:13:24.800 --> 0:13:28.360 an emergency where there's no you know, access to power, 0:13:28.600 --> 0:13:32.320 you can listen to radio signals and find out what's 0:13:32.320 --> 0:13:36.360 going on. A lot of bicycle lamps work in this 0:13:36.440 --> 0:13:41.560 way too. The lamps connect to the actual pedals, the 0:13:41.559 --> 0:13:44.000 pedal system of the bike, and so as you pedal 0:13:44.040 --> 0:13:48.360 the bike, you're also powering the dynamo that provides electricity 0:13:48.400 --> 0:13:51.640 to the lamp so that you can light your way 0:13:51.679 --> 0:13:55.240 if you're riding around in the dark. So if you 0:13:55.320 --> 0:13:59.400 were to offload this physical work to something else, then 0:13:59.800 --> 0:14:04.079 you can generate electricity without having to you know, exhaust 0:14:04.120 --> 0:14:06.600 people in the process. This is how stuff like wind 0:14:06.679 --> 0:14:10.200 power works. How hydro power works. Actually, it's how nuclear 0:14:10.240 --> 0:14:13.679 power works. Nuclear power doesn't do it through water, it 0:14:13.720 --> 0:14:15.880 does it through steam. I guess technically you could say 0:14:15.880 --> 0:14:18.480 water because it's water vapor, but yeah, it generates high 0:14:18.520 --> 0:14:22.200 pressure steam to turn turbines. But you know, hydro power 0:14:22.480 --> 0:14:25.720 just uses flowing water to turn turbines. Wind power obviously 0:14:25.840 --> 0:14:29.320 uses wind to turn turbines, but all of these ultimately 0:14:29.440 --> 0:14:35.120 end up powering electrical generators. So with a hydro electric dam, 0:14:35.560 --> 0:14:39.560 you've got your dam. Your dam blocks the passage of water, 0:14:40.160 --> 0:14:44.440 and you've got essentially a lake that forms on one side, 0:14:44.520 --> 0:14:47.000 and you do allow water to go through the dam, 0:14:47.080 --> 0:14:51.000 otherwise it wouldn't generate electricity for you. But on the 0:14:51.040 --> 0:14:54.280 other side you have your your continuing river. Right, So 0:14:54.840 --> 0:14:59.240 inside the dam itself, you've got channels or pipes where 0:14:59.320 --> 0:15:03.160 you allow water to pass through from an area of 0:15:03.400 --> 0:15:09.560 higher elevation to lower elevation. And what you're doing is 0:15:09.600 --> 0:15:12.120 you're allowing gravity and water to do a whole lot 0:15:12.200 --> 0:15:15.600 of work on your behalf. Now, the difference between the 0:15:15.640 --> 0:15:19.320 area of high elevation and the area of low elevation 0:15:19.800 --> 0:15:25.360 is called the dam's head. The amount of head determines 0:15:26.520 --> 0:15:29.200 sort of the pressure. How much pressure is going through 0:15:29.520 --> 0:15:34.240 this system. So if there's a very small difference in elevation, 0:15:34.840 --> 0:15:37.160 then the pressure is going to be much lower. If 0:15:37.160 --> 0:15:40.240 there's a greater difference, if the water is coming from 0:15:40.440 --> 0:15:44.720 very high and moving to very low elevation, then that 0:15:44.800 --> 0:15:47.720 water's going to be moving at much greater pressure. And 0:15:47.800 --> 0:15:52.160 at the base of this channel or pipe that's in 0:15:52.200 --> 0:15:56.720 the dam, you have a turbine, and a turbine's essentially 0:15:56.800 --> 0:16:00.520 a type of fan with blades that are designed to 0:16:00.600 --> 0:16:04.360 turn when the whole mess of water is flowing through 0:16:04.400 --> 0:16:07.280 the turbine. There are different designs of turbines. We're going 0:16:07.320 --> 0:16:11.200 to talk about those in a moment. So the type 0:16:11.240 --> 0:16:14.440 of turbine you use is typically determined by the kind 0:16:14.480 --> 0:16:19.080 of dam you're building, and the things like how much 0:16:19.520 --> 0:16:22.320 elevation change are you working with, how much pressure is 0:16:22.360 --> 0:16:26.440 going through what sort of flow rate are you looking at, 0:16:26.600 --> 0:16:28.120 like is it going to be a high flow rate 0:16:28.200 --> 0:16:31.479 or low flow rate? All of these things will determine 0:16:31.720 --> 0:16:36.119 which turbine would be best suited for that particular application. 0:16:36.600 --> 0:16:40.480 Because not all turbines work perfectly under all conditions. Some 0:16:40.560 --> 0:16:44.200 are ideal for very specific applications, and you want to 0:16:44.280 --> 0:16:47.880 use the one that's best suited for the way you're working, 0:16:47.960 --> 0:16:50.320 because that's going to be the most efficient means for 0:16:50.400 --> 0:16:53.640 you to generate electricity. Now, you can then take the 0:16:53.800 --> 0:16:58.520 alternating current created by one simple generator, and with the 0:16:58.600 --> 0:17:02.560 use of transformers, you can boost the voltage that is 0:17:02.720 --> 0:17:08.159 output for the purposes of transmitting electricity across long distances. 0:17:08.400 --> 0:17:14.200 Higher voltages transmit through wires with less power loss over 0:17:14.800 --> 0:17:19.080 length of transmission. So typically for transmission, you want to 0:17:19.119 --> 0:17:21.919 boost the voltage up really high if you're going to 0:17:21.920 --> 0:17:25.480 be transmitting that electricity across longer distances. We're talking about 0:17:25.520 --> 0:17:28.639 alternating current here again, Like if it's direct current, you 0:17:28.760 --> 0:17:32.560 typically want to keep your load that is, the thing 0:17:32.600 --> 0:17:37.320 that's using the electricity fairly close to the area of 0:17:37.440 --> 0:17:39.760 creating the electricity in the first place, the power plant 0:17:39.800 --> 0:17:42.439 in other words, But with alternating current, you want to 0:17:42.600 --> 0:17:46.480 up the voltage so that you can push this electricity 0:17:46.560 --> 0:17:48.560 out to where it needs to be, and then you 0:17:48.560 --> 0:17:52.239 would have a secondary transformer on the other end that 0:17:52.280 --> 0:17:55.560 would step down the voltage for the purposes of distributing 0:17:55.560 --> 0:17:58.640 the electricity to power homes and businesses and that kind 0:17:58.680 --> 0:18:02.120 of thing. So you've got transformers on either end, on 0:18:02.119 --> 0:18:04.800 one end to really boost the voltage, on the other 0:18:04.880 --> 0:18:07.719 end to bring the voltage back down. And transformers are 0:18:07.720 --> 0:18:10.480 actually pretty simple. You could argue that they are not 0:18:10.840 --> 0:18:15.280 more than meets the eye. You have essentially two coils 0:18:15.520 --> 0:18:19.800 of wire or cable inside a transformer. Now you also 0:18:19.960 --> 0:18:24.400 have an iron core inside the transformer. The easiest way 0:18:24.480 --> 0:18:28.280 I would use to envision the iron core is think 0:18:28.320 --> 0:18:31.800 about like almost like a picture frame, but it's made 0:18:31.800 --> 0:18:33.880 out of iron. And so you've got a left side 0:18:33.960 --> 0:18:36.560 and a right side of this right on the left 0:18:36.560 --> 0:18:41.040 side you have looped a coil of conductive wire, and 0:18:41.119 --> 0:18:43.959 on the right side you have a different loop of 0:18:44.160 --> 0:18:47.359 conductive wire. Let's say the left side is our primary 0:18:47.480 --> 0:18:53.400 coil or our primary winding. This length is ultimately connected 0:18:53.400 --> 0:18:57.520 to a source of electricity, so our generator. In other words, 0:18:57.600 --> 0:19:01.879 so the incoming electricity goes to the primary winding of 0:19:01.960 --> 0:19:07.680 our transformer. The other side, the other coil, it connects 0:19:07.680 --> 0:19:12.040 to an outgoing path. This is our secondary winding. And 0:19:12.680 --> 0:19:16.119 what happens with the voltage depends upon the difference between 0:19:16.119 --> 0:19:21.720 the number of turns or coils per side of primary 0:19:21.800 --> 0:19:25.960 versus secondary. So let's say we want to step up 0:19:26.320 --> 0:19:30.080 the voltage. We've got electricity coming from our generator. We 0:19:30.119 --> 0:19:32.240 want to step up the voltage so that we can 0:19:32.560 --> 0:19:36.280 push electricity across miles and miles and miles of cable. 0:19:36.920 --> 0:19:40.359 So to step it up, we have the electricity pass 0:19:40.440 --> 0:19:44.439 through the primary winding wrapped around this iron core, and 0:19:44.480 --> 0:19:48.200 the secondary winding. We have double the number of turns 0:19:48.400 --> 0:19:51.360 that the primary winding has. So let's say the primary 0:19:51.359 --> 0:19:55.359 winding has you know, twenty loops around the iron core. 0:19:55.680 --> 0:19:59.840 The secondary winding has forty loops wrapped around the iron core. 0:20:00.680 --> 0:20:05.480 And as alternating current electricity flows through the primary winding, 0:20:05.720 --> 0:20:09.000 it generates a magnetic field. This magnetic field is also 0:20:09.160 --> 0:20:13.240 guided by that shared iron core, and the magnetic field 0:20:13.280 --> 0:20:17.080 is also fluctuating because we're talking about alternating current, right, 0:20:17.119 --> 0:20:20.520 The current itself is changing directions many times a second, 0:20:20.720 --> 0:20:23.879 which means the magnetic field essentially is doing little flippy 0:20:23.880 --> 0:20:27.359 flops many times a second. And our secondary set of 0:20:27.680 --> 0:20:31.760 turns or coils, remember it has twice as many as 0:20:31.800 --> 0:20:35.679 the primary. It's within range of this fluctuating magnetic field 0:20:35.680 --> 0:20:37.960 that's guided by the iron core, and that means we 0:20:38.000 --> 0:20:41.840 have another case of induction. It is inducing electric charge 0:20:41.960 --> 0:20:45.720 in the secondary windings, and because there are more turns 0:20:45.880 --> 0:20:49.360 in this winding, it's stepping up the voltage. We get 0:20:49.440 --> 0:20:53.520 more voltage coming out than we did going in because 0:20:53.560 --> 0:20:57.399 of this relationship between the number of turns or coils 0:20:57.480 --> 0:21:00.800 in the two windings. So we zap electricity across miles 0:21:00.800 --> 0:21:04.000 and miles of cable. Because voltage is kind of like pressure, 0:21:04.240 --> 0:21:07.320 so the higher the voltage, the stronger the push is. 0:21:07.920 --> 0:21:10.199 Now the other end of those miles of cable, we 0:21:10.280 --> 0:21:14.440 have another transformer, only this one has a secondary coil 0:21:14.640 --> 0:21:20.040 or secondary winding that has fewer turns or loops than 0:21:20.040 --> 0:21:24.200 our primary winding does. So, once again, the fluctuating magnetic 0:21:24.200 --> 0:21:27.800 field generated by the primary coil induces an electric charge 0:21:27.840 --> 0:21:31.120 in the secondary coil. But because there are fewer loops 0:21:31.480 --> 0:21:36.320 in this secondary coil, we have a step down in voltage. 0:21:36.560 --> 0:21:40.720 Now that's the bare basics of electrical transformers. There is 0:21:40.760 --> 0:21:43.879 more to it than that. That gets more complicated. So 0:21:43.880 --> 0:21:46.120 I guess you could argue that, yes, there is more 0:21:46.160 --> 0:21:48.600 than meets the eye, but it's good enough for our 0:21:48.600 --> 0:21:51.720 purposes of this episode. All Right, Now we're going to 0:21:51.800 --> 0:21:54.080 take another quick break. When we come back, I'm going 0:21:54.160 --> 0:21:58.440 to talk about the evolution of turbines and which turbine 0:21:58.560 --> 0:22:03.240 is best used for a power generation scenario, and then 0:22:03.280 --> 0:22:07.000 we'll conclude with a little more talk about hydroelectric power 0:22:07.080 --> 0:22:09.920 and where that really got started. But first let's take 0:22:09.920 --> 0:22:22.080 another quick break. Okay, we're going back to turbines. So 0:22:22.160 --> 0:22:24.920 there is a long history of engineering for these things 0:22:24.920 --> 0:22:28.840 as well. A nineteenth century French engineer named ben wa 0:22:29.240 --> 0:22:34.480 fournee a Ron, whose name I have totally butchered, developed 0:22:34.480 --> 0:22:36.879 a turbine that was based on a water wheel design 0:22:36.960 --> 0:22:41.640 created by his former instructor Claude Burden. As the Encyclopedia 0:22:41.680 --> 0:22:45.600 Britannica puts it, in eighteen twenty seven, ben Wah built 0:22:45.760 --> 0:22:49.919 quote a small six horsepower unit in which water was 0:22:49.960 --> 0:22:54.560 directed outward from a central source onto blades or veins 0:22:54.560 --> 0:22:58.240 set at angles in a rotor end. Quote. He called 0:22:58.280 --> 0:23:00.720 it a turbine, and we would continue you tweaking his 0:23:00.840 --> 0:23:05.359 design to create more efficient powerful water wheels. Now, initially 0:23:05.400 --> 0:23:09.720 these were not used as hydroelectric power generators. They were 0:23:09.800 --> 0:23:13.960 instead used to do physical work for industrial purposes such 0:23:14.000 --> 0:23:17.320 as milling grain. However, much later at the end of 0:23:17.359 --> 0:23:20.400 the nineteenth century, his designs would be used in some 0:23:20.640 --> 0:23:24.399 hydroelectric dams, namely the American side of Niagara Falls in 0:23:24.440 --> 0:23:29.360 eighteen ninety five. In eighteen forty nine, however, an American 0:23:29.400 --> 0:23:34.520 engineer named James Francis created a turbine designed that would 0:23:34.600 --> 0:23:37.600 later be known as the Francis turbine. These turbines work 0:23:37.680 --> 0:23:42.080 well if they're either in horizontal or vertical alignment, so 0:23:42.560 --> 0:23:46.520 they're pretty versatile. They're also good for medium to large 0:23:46.560 --> 0:23:50.840 scale hydroelectric operations, and it's what I would call a 0:23:50.880 --> 0:23:56.000 semi reaction turbine. So there are different types of turbines. 0:23:56.040 --> 0:24:01.040 Some are called impulse turbines. Impulse turbines work from water 0:24:01.480 --> 0:24:05.119 forcing the turbine to turn. It's the force of impact 0:24:05.280 --> 0:24:10.240 of water against turbine that causes rotation. Those are impulse turbines. 0:24:10.640 --> 0:24:15.080 Reaction turbines depend on something else like water pressure, where 0:24:15.400 --> 0:24:18.679 the design of the fan blades in the turbine means 0:24:18.720 --> 0:24:21.400 that you have an area of low pressure on one 0:24:21.440 --> 0:24:24.240 side of the blades and high pressure on the other, 0:24:24.720 --> 0:24:28.760 and that difference in pressure causes the turbine to rotate. 0:24:29.280 --> 0:24:32.440 The Francis turbine is kind of a combo between the two. 0:24:32.720 --> 0:24:37.280 So it's turned partly through the force of water hitting 0:24:37.359 --> 0:24:42.480 the blades and partly through this pressure differential. So it's 0:24:42.520 --> 0:24:45.200 a semi reaction turbine, is how. Some people call it 0:24:45.240 --> 0:24:47.280 a reaction turbine. Some say, well, it's not a true 0:24:47.280 --> 0:24:50.040 reaction turbine. So that's kind of where I get wishy 0:24:50.160 --> 0:24:53.840 washing called semi reaction turbine. But yeah, that area of 0:24:53.840 --> 0:24:55.879 low pressure on one side and high pressure on the 0:24:55.880 --> 0:24:58.800 other is part of the reason this turbine turns. Also, 0:24:58.880 --> 0:25:02.600 incoming water is direc acted inward toward the center of 0:25:02.640 --> 0:25:06.800 the turbine, so the water enters radially. So water is 0:25:06.920 --> 0:25:10.960 entering from around the turbine, around the circumference of the turbine, 0:25:10.960 --> 0:25:14.800 if you will, but it flows out axially, meaning the 0:25:14.840 --> 0:25:19.080 water is ejected in parallel to the axis of the 0:25:19.119 --> 0:25:22.959 turbine's rotation. And these turbines make up more than half 0:25:23.040 --> 0:25:26.480 of the kinds used in hydroelectric dams today. They're kind 0:25:26.520 --> 0:25:31.200 of like the Goldilocks of turbines. They're good for dams 0:25:31.240 --> 0:25:35.480 that are in the middle spot, the sweet spot. Lester 0:25:35.640 --> 0:25:39.000 Allen Pelton created his own turbine in the eighteen seventies, 0:25:39.000 --> 0:25:42.280 so this is after Francis has created the Francis turbine. 0:25:42.680 --> 0:25:46.199 This one we call the Pelton wheel and it kind 0:25:46.240 --> 0:25:48.439 of makes me think of like a ferris wheel or 0:25:48.480 --> 0:25:52.359 a vertical water wheel. It works best for hydroelectric facilities 0:25:52.640 --> 0:25:55.960