How stuff works Engineering Sciences and Technology INTRODUCTION - PART ONE 1/ Watch the first part of the video twice (“introduction - part one.avi”). Fill in the blanks while and after listening. (one blank = one word) You may have been driving through the countryside and suddenly come up on something like a tall tower with big triple blade at the top rotating and you wonder what it is: it is a wind turbine. The purpose of this is to generate electricity and they tend to be extremely big so you see them in the distance, but when you get close to them, they are very big. The other problem with them is they do produce pollution, so be careful, but it's sound pollution. Many people find i t very disturbing the noise these things make as these blades woosh past you. So be aware of that. All it is, is basically a tall, concrete, stress concrete tower and on top of it, is a generator, an electric generator. The electric generator is very simple, it can be mounted right on the top of here and it is driven directly by the fan blade. 2/ What are the main components of a wind turbine ? A wind turbine is composed of: A tall concrete tower with an electric generator mounted on top which is driven by a big triple fan blade 3/ Point them out on the picture below. Triple fan blade Electric Generator Tall Concrete Tower The wind turbine. Page 1 4/ What is the goal of the wind turbine? The goal of the wind turbine is to generate clean and renewable electricity from wind power. 5/ What kind of environmental impact does the system create? The system does create sound pollution from the rotating blades 6/ How does the electric generator move? The wind drives the triple blade fan and puts it in rotation INTRODUCTION - PART TWO 1/ Watch the second part of the video twice (“introduction - part two.avi”). Fill in the blanks while and after listening. (one blank = one word) Now obviously, there is at this point what we call a gearbox because, obviously, the blade goes round quite slowly and if it went round that slowly, the generator wouldn't generate much electricity. But there is a gear box to speed up the rotation in the generator so even though this goes round quite slowly, the generator is at its full capacity and will generate electricity. This electricity then is fed down the tower and out to the electricity grid where it can supplement electricity produced in other ways. It is interesting to note that you can not just put them anywhere. Obviously, the energy which is used is wind energy and the air is moving. And as the air moves past, the energy is removed from the air. So, you can't put a lot of them very close to each other because one will affect the work of the other. And in fact, that's why you see they're fairly well spread out because they have to have their own area of air to work in. So that's a wind turbine; how it works and how it is set up . If you see one, just think, this will be producing energy for the foreseeable future. 2/ The blade rotates? slowly at a medium speed fast 3/ The electric generator rotates? slowly The wind turbine. at a medium speed fast Page 2 4/ What is the purpose of the gear box? It matches the fan rotation speed to the one required by the asynchronous motor to generate electricity 5/ Here is the internal block diagram of the wind turbine. ▪ Fill in the two missing parts in the diagram. ▪ Fill in the three missing links (these links are energy…). : Blade Fan Wind Energy :Electric Generator Rotational mechanic energy (high speed) Electric Energy (~AC) 6/ Why can't we implement two wind turbines very close to one another? When harvested by the blade fan, the air loses its potential energy and therefore doesn’t have the power to drive infinite number of blade fans. That’s why it’s required for wind turbines to be spread out. DECONSTRUCTED - PART ONE 1/ Watch the first part of the video twice (“Deconstructed - part one.avi”). Fill in the blanks while and after listening. (one blank = one word) Wind turbine blades are aerodynamically designed to catch the maximum amount of wind energy to make them rotate. Inside the t u r b i n e , an electromagnetic system transform that Rotational movement into electricity that is stored in a battery. The stronger the wind, the faster the blades rotate, the more power generated. Getting the blades moving is the first step and to do that, of course, requires a strong, steady, wind. The carbon fiber blades are aerodynamic to fully exploit wind power. One surface is rounded, the other relatively flat. Wind flowing over the rounded sides speeds up and creates a low pressure pocket that sucks the blades sideways, what's known as lift . Now that lift sets the blades in motion, let's see how this rotation can be turned into wattage to power the fridge or stove. The wind turbine. Page 3 2/ Why are blades made in carbon fiber? Carbon fiber is a strong material with a high strength to weigh ratio, which means it can sustain a lot a mechanical constraint while remaining light. 3/ Give an example of another system which uses lift process. This effect is also exploited in aircraft and race-cars 4/ Compare the wind turbine from video n°1 (Introduction) and the one from video n°2 (Deconstructed). Video n°1 (Introduction) Video n°2 (Deconstructed) Tall Small Made out of concrete On a metal tripod Rotates slowly Rotates fast Connected to the electric grid Connected to a battery Gear box Direct drive DECONSTRUCTED - PART TWO 1/ Watch the second part of the video twice (“Deconstructed - part two.avi”). Fill in the blanks while and after listening. (one blank = one word) When the blades turn, they spin a shaft Twelve small magnets connected to a rotor inside a generator. fixed around the rotor turn inside the stator made of coils of copper wire. These magnets are an alloy of neodymium, iron and boron. They are small but powerful . In fact, they're among the most powerful magnets on earth. The turbine needs their incredible strength to turn the blades' rotational energy into electricity. When the magnets rotate inside the stator, they create a moving magnetic field and the laws of electromagnetism dictate what follows : electrons in the copper coil also start moving. The movement of these electrons produces what's called an alternating current, the kind that comes out of conventional wall outlets. 2/ What the function of the shaft? It drives the rotor from the rotation movement of the blades The wind turbine. Page 4 3/ Explain how generator creates alternating current. The rotation of magnets (and therefore their respective magnetic field) inside a set of copper coil sets the electrons in motion which generates an alternative current 4/ At home, where can you find alternating current? Out of a conventional wall outlet. DECONSTRUCTED - PART THREE 1/ Watch the third part of the video twice (“Deconstructed - part three.avi”). Fill in the blanks while and after listening. (one blank = one word) Alternative Current is easy to produce and to distribute battery but impossible to store . It needs to be transformed into a direct current in a in order to be contained. This electronic circuit inside the turbine does the job. With winds of twenty-height miles per hour , this particular turbine can produce four hundreds watts of power, enough to light up four one hundred watt light bulbs. It doesn't seem like much. But the wattage can be boosted by accumulating and storing the energy in the battery. STRUCTURAL DIAGRAM 1/ Look at the flash document named "How wind power works". From what you can see and understand, fill in the structural diagram Rotor (fan) Tower Nacelle Shaft Gearbox Transformer Electric Generator below. The wind turbine. Page 5 3/ Explain how generator creates alternating current. VOCABULARY LIST: The wind turbine. Alloy Un alliage (métallurgie) An outlet (electric) Une prise électrique Concrete (noun) Béton Copper Cuivre Fan Ventilateur Gear Box Boite de vitesses Magnet Aimant Motion Mouvement Shaft Axe, Arbre (moteur) To Spin Faire tourner Steady Régulier, stable, constant To Disturb Déranger To Harvest Récolter To Rotate Faire pivoter To Store Stocker, emmagasiner Wind Turbine Eolienne Page 5
