WEBVTT 00:00:00.291 --> 00:00:03.968 What is hydroelectric energy? 00:00:05.267 --> 00:00:08.580 It is the energy produced thanks to the force of water. 00:00:08.888 --> 00:00:15.023 A static mass of water contains potential energy which is converted into kinetic energy 00:00:15.023 --> 00:00:19.333 when it is set in motion thanks to the force of gravity. 00:00:19.999 --> 00:00:23.129 All of this takes place in a hydroelectric power plant. 00:00:24.429 --> 00:00:26.407 There are three types of hydroelectric power plants: 00:00:26.611 --> 00:00:27.962 Run-of-river hydroelectric power plant 00:00:27.962 --> 00:00:29.420 Conventional hydroelectric power plant 00:00:29.623 --> 00:00:32.463 Pumped storage hydroelectric power plant 00:00:36.193 --> 00:00:39.848 Let's take a closer look at each type. 00:00:40.327 --> 00:00:42.588 Run-of-river hydroelectric power plant 00:00:44.110 --> 00:00:49.522 It takes advantage of the natural flow of a water course by being located on two different levels. 00:00:50.281 --> 00:00:54.513 How does it work? The water is collected and begins to flow through a channel 00:00:54.513 --> 00:00:59.268 equipped with a filter for solid material, such as waste, and into a charge basin. 00:00:59.610 --> 00:01:02.850 The water travels a height difference through a high pressure pipe 00:01:03.000 --> 00:01:05.432 and reaches the engine room where the turbine is located 00:01:05.536 --> 00:01:08.816 and rotates thanks to the push of the water. 00:01:10.008 --> 00:01:10.696 Engine Room 00:01:10.696 --> 00:01:19.074 Inside the engine room we find the turbine and the rotating electric generator. 00:01:19.754 --> 00:01:20.903 The turbine consists of: 00:01:20.903 --> 00:01:25.847 The stationary part (distributor) which has the task of directing and regulating the flow of water 00:01:25.847 --> 00:01:32.516 The moving part (impeller) which, pushed by water, generates mechanical energy 00:01:33.981 --> 00:01:40.396 The rotating electric generator (alternator), mounted and connected directly to the turbine shaft, 00:01:40.569 --> 00:01:45.516 transforms the mechanical energy received from the turbine into electrical energy. 00:01:46.323 --> 00:01:47.383 Types of turbines 00:01:47.383 --> 00:01:54.000 Francis It is a centripetal flow turbine: the water reaches the impeller through a spiral conduit. 00:01:54.267 --> 00:02:00.279 Then adjustable palettes on the stationary part direct the flow so as to strike the impeller blades. 00:02:00.789 --> 00:02:08.096 It is used for medium height differences (from 10 up to 300/400 meters) and from 2 to 100 cubic meters per second of water capacity. 00:02:09.000 --> 00:02:16.300 Kaplan It is an axial type of turbine consisting of a distributor and a rotating propeller, similar to the one used in a boat's engine. 00:02:16.783 --> 00:02:23.630 The water flow that turns the propeller blades enters and exits in an axial direction with respect to the propeller’s axis of rotation. 00:02:24.000 --> 00:02:27.423 As the blades’ angle of incidence can be adjusted, 00:02:27.423 --> 00:02:30.918 it ensures optimum performance with the presence of small height differences, 00:02:30.918 --> 00:02:34.857 but also with large variations in capacity (from 200 cubic meters per second and above). 00:02:36.653 --> 00:02:43.124 Afterwards, the water is directed into a return channel and fed back into the water course. 00:02:44.589 --> 00:02:49.839 The power developed by run-of-the-river hydroelectric power plants depends on the flow of the water course 00:02:49.973 --> 00:02:55.205 and the so-called jump, that is, the difference in height between the altitude from which the water is collected and where it is returned. 00:02:56.337 --> 00:02:58.131 Conventional hydroelectric power plant 00:02:59.049 --> 00:03:03.000 It is based on the use of a water basin (reservoir) which can be of natural or artificial origin. 00:03:03.000 --> 00:03:06.820 The water is conveyed, at times, even with a complex collection system 00:03:06.906 --> 00:03:10.438 consisting of canals, tunnels, gutter pumping systems 00:03:10.438 --> 00:03:14.263 towards the barrier (dam) used to store the water at the highest altitude. 00:03:15.932 --> 00:03:16.756 Types of dams 00:03:16.841 --> 00:03:22.081 Gravity dams They are massive structures with simple geometry including a straight axis and a triangular section. 00:03:22.150 --> 00:03:27.315 Its resistance to water pressure is due to the weight of the structure itself. 00:03:28.803 --> 00:03:34.015 Arch dams They resist the hydrostatic pressure of the reservoir water, transferring it to the side walls of the structure. 00:03:34.086 --> 00:03:40.808 They have a convex shape and are generally constructed across relatively narrow valleys with rocky sides where there are stable natural supports. 00:03:41.612 --> 00:03:46.511 How does it work? The water is collected from the basin and flows into a system of pipes, 00:03:46.579 --> 00:03:52.096 until it reaches the engine room, where the turbine starts to rotate thanks to the push of the water. 00:03:53.760 --> 00:03:54.931 Types of turbines 00:03:54.931 --> 00:04:01.260 Generally, a Pelton turbine is used: the water is conveyed into the high pressure pipe 00:04:02.334 --> 00:04:07.055 which at the end has a nozzle, a bottleneck that increases the velocity of the water 00:04:07.055 --> 00:04:12.203 by directing it towards the impeller blades, which are spoon-shaped. 00:04:12.818 --> 00:04:17.081 It is used for large height differences (between 300 and 1400 meters) 00:04:17.201 --> 00:04:22.572 and less than 50 cubic meters per second of water capacity, in order to achieve a higher speed. 00:04:24.000 --> 00:04:30.737 The water is then drained into a return channel and flows back into its course. 00:04:31.097 --> 00:04:35.343 This type of plant allows for better control of water flows, 00:04:35.515 --> 00:04:41.369 thus managing to regulate them according to the needs at certain times of the day or at certain times of the year. 00:04:43.333 --> 00:04:48.833 This is why it is also known as a regulated outflow hydroelectric power plant. 00:04:50.321 --> 00:04:52.141 Pumped storage power plant 00:04:52.845 --> 00:04:58.581 It has two reservoirs at different altitudes, one upstream and one downstream. 00:04:58.753 --> 00:05:01.135 Through a pumping station, 00:05:01.205 --> 00:05:06.386 during times of lower energy demand, the water is brought up from the downstream basin to the upstream basin. 00:05:07.260 --> 00:05:12.446 How does it work? From the upstream basin, the water is collected and sent through the high pressure pipe 00:05:12.446 --> 00:05:18.296 to the engine room, where the turbine starts to rotate thanks to the push of water. 00:05:19.477 --> 00:05:20.653 Types of turbines 00:05:20.653 --> 00:05:24.854 Generally, a centripetal flow turbine, Francis, is used which, coupled to an alternator, 00:05:25.025 --> 00:05:27.025 transforms the rotation movement into electricity. 00:05:29.677 --> 00:05:33.540 As a result, the water is drained into the downstream basin. 00:05:34.139 --> 00:05:37.258 During times of low energy demand, 00:05:37.258 --> 00:05:41.709 the plant brings the water back to the upstream basin through a turbine that functions as a pump, 00:05:41.777 --> 00:05:44.273 absorbing energy from the power grid. 00:05:45.352 --> 00:05:49.188 In this way, it is possible to respond safely to increased energy demands, 00:05:49.393 --> 00:05:54.884 such as during the daytime, allowing the same water pumped during low consumption hours 00:05:54.953 --> 00:05:57.412 to be reused to overcome the so-called demand peaks. 00:05:57.946 --> 00:06:02.313 This contributes to the safety of the electrical system. 00:06:04.373 --> 00:06:10.294 Hydroelectricity is one of the renewable technologies that offers a key contribution to the regulation of the power grid 00:06:10.721 --> 00:06:15.798 and that is able to respond swiftly and efficiently to changes in demand. 00:06:16.704 --> 00:06:19.647 Now we are ready to distribute energy. 00:06:21.000 --> 00:06:27.210 Through a transformer, the intensity of the current is lowered and the voltage is raised. 00:06:27.693 --> 00:06:34.230 In this way, the generated current is fed directly into the distribution network, which will power homes and businesses 00:06:34.794 --> 00:06:41.111 by lowering the voltage according to the needs of residential or industrial users.