1 00:19:42,180 --> 00:19:42,980 Hello. 2 00:19:43,180 --> 00:19:45,760 In this video in the series about renewable energy, 3 00:19:45,760 --> 00:19:47,100 we're going to talk about hydropower 4 00:19:47,100 --> 00:19:51,360 now I'm going to differentiate hydropower from tidal and wave energy. 5 00:19:51,640 --> 00:19:53,740 Completely different thing. 6 00:19:53,740 --> 00:19:57,540 Hydropower is power produced by water 7 00:19:57,880 --> 00:20:02,220 because of the energy stored in it due to the force of gravity. 8 00:20:02,260 --> 00:20:05,880 So we have a head of water now head means a height. 9 00:20:06,420 --> 00:20:07,860 So we have a dam. 10 00:20:07,860 --> 00:20:09,940 We have a dam with the head of water behind it. 11 00:20:10,440 --> 00:20:15,840 That water, because of its position above the turbines you are going to pass it 12 00:20:15,840 --> 00:20:19,040 through, contains potential energy, gravitational potential energy. 13 00:20:20,020 --> 00:20:23,880 You open a sluice, allowing that water to go downhill. 14 00:20:24,220 --> 00:20:25,420 It will gather momentum. 15 00:20:25,420 --> 00:20:28,180 It will increase Its velocity will accelerate. 16 00:20:28,440 --> 00:20:30,700 It will then come up against a turbine. 17 00:20:31,300 --> 00:20:34,420 Now we've spoken about wind turbines. 18 00:20:35,580 --> 00:20:37,240 A turbine 19 00:20:37,240 --> 00:20:40,380 driven by water is exactly the same. 20 00:20:41,200 --> 00:20:44,200 All you are doing is putting angled blades 21 00:20:44,860 --> 00:20:47,160 in a moving stream 22 00:20:47,580 --> 00:20:50,520 of a fluid, whether it be liquid or gas. 23 00:20:50,720 --> 00:20:55,380 Now, with liquids and gases, we term as fluids, so a wind turbine 24 00:20:55,720 --> 00:21:00,820 is using the fluid power of the wind a hydro turbine. 25 00:21:00,820 --> 00:21:04,920 A water turbine uses that water now 26 00:21:05,200 --> 00:21:07,780 because water is denser than air. 27 00:21:08,400 --> 00:21:11,560 Obviously, you don't need a turbine 28 00:21:11,560 --> 00:21:15,480 with such a large surface area to catch that energy. 29 00:21:16,420 --> 00:21:18,640 Now here's the big one. 30 00:21:19,200 --> 00:21:19,900 It's free. 31 00:21:19,900 --> 00:21:22,860 At the end of the day. 32 00:21:22,860 --> 00:21:25,240 Hydro power is powered by the Sun. 33 00:21:25,240 --> 00:21:28,680 Very, very strange statement. 34 00:21:29,360 --> 00:21:33,420 The sun heats up the sea, the water evaporates from the surface of the ocean 35 00:21:34,300 --> 00:21:37,040 that is then forced up as it comes over land. 36 00:21:37,320 --> 00:21:39,520 It cools down, it rains. 37 00:21:39,820 --> 00:21:44,740 The rain is gathered in a lake with a dam behind it. 38 00:21:45,600 --> 00:21:47,160 There it is. It's free. 39 00:21:47,160 --> 00:21:48,380 You don't have to do anything. 40 00:21:48,380 --> 00:21:51,100 Now there are other ways actually of getting water up there 41 00:21:51,580 --> 00:21:54,600 now with normal power generation. 42 00:21:54,880 --> 00:21:57,960 We cannot turn off power stations just like that. 43 00:21:58,300 --> 00:22:03,160 So there is always an excess of electricity during the quiet hours 44 00:22:03,160 --> 00:22:04,240 of the night. 45 00:22:04,240 --> 00:22:07,720 People's usage drops, but to actually lower 46 00:22:07,720 --> 00:22:12,040 the output of a generating plant takes two or three hours to stop. 47 00:22:12,100 --> 00:22:13,800 You can't just stop it. 48 00:22:13,800 --> 00:22:18,320 So we use that electricity to pump water back uphill because it's there. 49 00:22:18,320 --> 00:22:19,300 It's not being used. 50 00:22:19,300 --> 00:22:20,280 We can't turn it off. 51 00:22:20,280 --> 00:22:22,600 So why not use it to our advantage? 52 00:22:22,600 --> 00:22:25,240 There are certain turbines 53 00:22:25,240 --> 00:22:28,720 that, because of the design, can pump water 54 00:22:29,380 --> 00:22:32,440 as well as turn inside the water to produce energy. 55 00:22:32,600 --> 00:22:35,400 So you're taking rotational energy, pumping it 56 00:22:35,800 --> 00:22:39,960 back up the water into the dam and then you are recovering 57 00:22:39,960 --> 00:22:43,240 that energy again when it comes back down and it spins the turbine. 58 00:22:43,840 --> 00:22:46,900 Not very efficient. I grant you but. 59 00:22:46,900 --> 00:22:51,040 You are using a form of energy that will go to waste. 60 00:22:51,600 --> 00:22:52,380 We wouldn't use it. 61 00:22:52,380 --> 00:22:54,460 So why not use it to your best advantage? 62 00:22:54,680 --> 00:22:57,640 But as I did say before, ultimately 63 00:22:57,840 --> 00:23:03,120 the energy we get from water is there because of 64 00:23:03,460 --> 00:23:07,240 the photons from the sun again warming the surface of the ocean. 65 00:23:08,500 --> 00:23:10,360 It all comes down to the sun. 66 00:23:10,360 --> 00:23:11,380 In the next couple of videos, 67 00:23:11,380 --> 00:23:13,780 I'll be going into things that are not necessarily sun related. 68 00:23:13,960 --> 00:23:19,820 The energy we start harvesting is from the planet itself.