Lessons on Working with Wind Energy Capture And Generation of Electricity
adapted from – www.tryengineering.org To appreciate more about the physics of wind power: read by David JC MacKay “without the hot air” http://www.inference.phy.cam.ac.uk/withouthotair/c4/page_32.shtml http://www.inference.phy.cam.ac.uk/withouthotair/cB/page_263.shtml
The following video and website provide visual learning that can be reinforced with repetition.
A video about vertical axis wind turbine: http://www.quietrevolution.com/index.htm?gclid=COOk2-zM8LACFQQhtAodelT7uw
You can even build your own horizontal or vertical wind turbine. More information here: http://learn.kidwind.org/learn http://www.mdpub.com/Wind_Turbine/ http://www.thekevdog.com/projects/wind_generator/ http://www.youtube.com/watch?v=Zrp0RC3XTpw&feature=related
To calculate the performance of your wind turbine: http://learn.kidwind.org /challenge/web/turbine_performance_calculator
To know more about wind power and wind turbines: http://www.windandsun.co.uk/Wind/wind_marlec.htm http://www.lmwindpower.com/Blades.aspx
Lesson Focus The lessons all focus on how wind energy could be converted into movement energy and electrical energy on a small or a large scale. Adult learner teams will design and build a working wind mill out of everyday materials and learn how they can produce energy. The learners’ wind mills have to be able to sustain the wind generated by a fan or a blow hair dryer. Using a KidWind kit, learners will build an electric motor to use as an electric generator. Teams of 4 will build generators with different numbers of coils, with the same gauge or diameter of copper wire, winding around a specially made axle. Measurement of electrical energy will be done on a multimeter. Adult learners will evaluate effectiveness of their coiling variable with one type of windmill. They will present their findings to the rest of the class. Lesson synopsis The “working with wind capture” activity explores the use of wind energy to generate or augment in businesses and homes globally. Adult learners work in teams of “engineers” with different natural groups e.g. one UK, one RO, two ES or one IT and one ES learner, to design and build their own windmill out of everyday items which will be available. The teams test their generators and windmills, collate any results on an excel spreadsheet, present the results as a graph and present their reflections to the whole workshop. Age Levels 8-18 Objectives v Learn about electrical generators, their circuits and use of an electric multimeter. v Learn about wind energy and turbines. v Learn about engineering design. v Learn how engineering can help to solve Europe’s challenges. v Learn about teamwork and problem solving in a transnational project. Anticipated Learner Outcomes As a result of this activity, on reflection adult learners should develop an understanding of: v Wind energy. v Interaction of technology and society’s issues. v Data handling mathematical skills. v Engineering planning and design. v Teamwork. Lesson activity Learners explore the impact of how technology can positively impact the world by learning about wind energy and equipment used for both site testing and the conversion of wind to energy. Learners explore the technology behind wind energy, find out about site studies, and work in teams to develop a windmill out of everyday items. They test their windmills, evaluate their own designs and those of other learners, and present their findings to the class. Resources/Materials
Alignment to Curriculum Framework The workshop is appropriate for: - Key stage 2, year 6 - Key stage 3, year 7 to 9 - BTEC engineering - GCSE technology and physics; key stage 4 - Electrical apprentice courses - Tutor, teacher, instructors training courses - Hobbyist informal self learning Website links - TryEngineering (www.tryengineering.org) - National Renewable Energy Laboratory – Wind Research (www.nrel.gov/wind) - Wind Powering America (www.windpoweringamerica.gov) - European Wind Energy Association (www.ewea.org) - Danish Wind Industry Association (www.windpower.com) - Global Wind Energy Council (www.gwec.com) - Global Wind Day (www.globalwindday.org) - National Science Education s (www.nsta.org/publications/nses.aspx) - ITEA s for Technological Literacy (www.iteaconnect.org/TAA) Recommended Reading - Wind Power : Renewable Energy for Home, Farm, and Business (ISBN : 1931498148) - Wind Energy Basics : A Guide to Small and Micro Wind Systems (ISBN : 1890132071) - The Homeowner’s Guide to Renewable Energy (ISBN : 086571536X) Optional Writing Activity (in the language of the participant) Write an essay about whether a wind farm, even if it would provide energy to the local energy consumer, would be a good idea to put in the centre of your home town. What about the River Thames in London or just off a resort beach area or a nature park? For Teachers and Tutors: T Resources Lesson Goal Learners explore the impact of how technology can positively impact the world by learning about wind energy and equipment used for both site testing and the conversion of wind to energy. Learners explore the science and technology behind wind energy, find out about site studies, and work in teams to develop a windmill out of everyday items. They test their windmills, evaluate their own designs and those of other Learners, and present their findings to the class. Lesson Objectives v Learn about electrical generators, their circuits and use of an electric multimeter. v Learn about wind energy and turbines. v Learn about engineering design. v Learn how engineering can help to solve Europe’s challenges. v Learn about teamwork and problem solving in a transnational project. Materials v Learner Resource Sheets v Learner Worksheets v Hair Dryer or Fan, and multimeter v Learners need to have a lap and memory stick, and a stopwatch found on mobile phones v One set of materials for each group of Learners: wooden stick, wooden spoons, small wooden (balsa) pieces, bendable wire, string, paperclips, rubber bands, toothpicks, aluminium foil, tape, dowels, super glue, paper, cardboard, plastic wrap, or other materials available to the teacher locally Procedure 1. Show learners into the various Learner Reference Sheets. These may be read in class, or provided as reading material for the prior night’s homework. 2. Divide Learners into groups of 4 Learners, providing a set of material per group. 3. Explain that Learners must develop their own working windmill from everyday items, and that the windmill must be able to withstand a fast speed fan for 2 or 3 minutes. The average has to be taken (Note: as an extra challenge, test the windmill’s ability to lift heavier objects as coins or washers). 4. Learners could be “budget” from which they will need to purchase materials you provide. Assign a cost for each item that will result in the average team being able to purchase at least 30 material parts. 5. Learners meet and develop a plan for their windmill prior to the lesson. They agree on material they will need, write or draw their plan, and then present their plan to the class. 6. Learners groups next execute their plans. Learners teams may request exchange materials or order more materials from the teacher, or may also trade unlimited materials with other teams to develop their ideal parts list. They will need to determine the “cost” of their design; the design with the lowest manufacturing budget will be considered the most efficient classroom design. 7. Next teams will test their windmills with the fan or the hairdryer set up. (Note: you may wish to make the fan available during the building phase so they can test their windmill during the building phase prior to the classroom test). 8. Teams then complete an evaluation worksheet, and present findings to the class. Time needed Approximately 1-2 hours, max 3 hours session.
. Learner Resource: What is Wind Energy?
Wind is a form of solar energy. Winds are caused by the uneven heating of the atmosphere by the sun, the irregularities of the earth’s surface, and rotation of the earth. Wind flow patterns are modified by the earth’s terrain, bodies of water, and vegetation. Human use this wind flow, or motion energy, for many purposes: sailing, flying a kite, and even generating electricity. The terms ‘wind energy’ or ‘wind power’ describe the process by which the wind is used to generate mechanical power or electricity. By using energy from our environment, we can produce energy without producing greenhouse gasses. Wind power is free to use. The sail for thousands of years made the most important use of wind energy for transport across water. Wind have been used for centuries to drive windmills to make mechanical power for grinding of flour and pumping or movement of water. Today, wind is used to generate electricity using wind turbines. Wind turbines convert the kinetic energy in the wind into mechanical power. This mechanical power can be used for specific tasks (such as grinding grain or pumping water) or a generator can convert this mechanical energy into electricity.
How Wind Turbines Work A wind turbine works the opposite to a fan. Instead of using electricity to make wind, like a fan, wind turbines use wind to make electricity. The wind turns the blades, which spin a shaft, which connects to a generator and makes electricity. Wind turbines, like windmills, are usually mounted on a tower to capture the most energy. Wind turbines operate on a simple principle. The energy in the wind turns two or three propeller-like blades around a rotor. The rotor is connected to the main shaft, which spins a generator to create electricity. Wind turbines are mounted on a tower to capture the most energy. At 100 feet (30 meters) or more above ground, they can take advantage of faster and less turbulent wind. A blade acts much like an airplane wing. When the wind blows, a pocket of low pressure air is formed on the downwind side of the blade. The low-pressure air pocket then pulls the blade toward it, causing the rotor to turn. This is called lift. The force of the lift is actually much stronger than the wind force against the front side of the blade, which is called drag. The combination of lift and drag causes the rotor to spin like a propeller, and the turning shaft spins a generator to make electricity. The generator then produces electricity which is carried along power lines to wherever it is needed. Wind turbines can be used to produce electricity for a single home or building, or they can be connected to an electricity grid for more widespread electricity distribution. Wind speed and the height of the blades both contribute to the amount of energy generated. An interactive game from the Danish Wind Industry Association (www.windpower.org/en/knowledge/wind_with_miller.html) lets you explore this concept in a game. This a very interesting website cleverly designed for those who wish to go deeper into this topic. Horizontal and Vertical Wind Turbines There are two types of wind turbines: the horizontal axis wind turbine and the vertical axis wind turbines.
Horizontal axis wind turbine: This is probably the more familiar type. It has been modernized from the traditional windmill designs that have been with us for centuries. A nacelle installed perpendicular to the tower and horizontal with respect to the ground justifies the name of the turbine. These wind turbines have blades that face into the wind to gain energy from it. They must face into the wind in order to achieve maximum efficiency. To do this, the major part of these wind turbines has a tail or a weather vane, which acts as a sail, maintaining the blades facing the oncoming wind. This is mostly the case of the small turbines. The larger ones generally need a wind sensor coupled with a servo motor. Most have a gearbox which accelerates rotation of the blades until a speed more suitable for driving an electrical generator. Large wind turbines are now used in wind farms for commercial production of electric power. Small wind turbines can be used to provide some of the electrical energy that is needed to run your home. This energy can be used to either directly power some of the electrical devices or be fed back into the power grid to lower your electrical bill. Vertical axis wind turbine: These turbines have the main rotor shaft arranged vertically. The advantage of this arrangement is that the turbine does not need to be pointed into the wind to be effective. This is an advantage on sites where the wind direction is highly variable, for example when integrated into buildings. Manufacturers claim these turbines are quiet, efficient, economical and perfect for residential energy production, especially in urban environments. They are not as efficient as the horizontal ones because of a lower rotation speed, but they tend to be safer, easier to build, can be mounted close to the ground, and handles turbulence much better. The design is very diverse as you can see on the right.
Learner Resource: Site Testing for Wind Energy
Not all locations are suitable for wind energy development. They need to be evaluated to determine if the cost associated with installing a wind turbine will likely be balanced by the value of energy generated over time. One of the first steps to developing a wind energy project is to assess the area wind resources and estimate the available energy. To help the wind industry identify the area best suited for development, the U.S. Wind Energy Program works with the National Renewable Energy Laboratory (NREL) and other organisations to measure, characterise, and map wind resources 50 meters (m) to 100 m above ground. At the local level, towns and contractors will work with homeowners to determine the cost and likely financial benefits of wind turbine installation. Often the first step is to temporarily install an anemometer to test the wind at a farm or home over several months or even a year. European adult learners could as an assignment research the best sites in Europe and learn about wind energy programs of their countries.
Using Anemometers to test Wind Potential An anemometer is a device that is used for measuring wind speed. Many countries and organisations offer anemometer loan programs, so a company or individual can evaluate the wind at their site to determine if enough wind energy would be generated at the location. For these test sites, an anemometer might collect wind-speed data in 10-minute intervals over a long period of time.
Global Wind Day! “Global Wind Day” on June 15 of each year to raises awareness of wind energy worldwide. Thousands of public events are organised simultaneously around the world. More information is at www.globalwindday.org . . Learner Resource: Blade Options
Blade Design Blade comes in many shapes and sizes, and there is continuing research into which design is best. It turns out that the optimal design really depends on the application, or where and how the blades will be used. Designers look at the “tip speed ratio” that determines efficiency. This is the ration between the speed of the wind and the speed the blade tip. High efficiency 3-blade-turbines have tip speed/wind speed ratios of between 6 and 7.
How Many Blades? Most wind turbines use either two or three blades. Research indicates that as more blades are added there is an increase in aerodynamic efficiency, but this efficiency increase actually decreases dramatically with each added blade. For example, increasing the number of blades from one to two can yield a 6 percent increase in aerodynamic efficiency, but increasing the blade count from two to three yields only an extra three percent in efficiency. And, of course, there are cost implications too. Each additional blade in a design will increase the cost of the end product, so engineers have to factor in both the increased efficiency and the increased cost in manufacturing to determine a design that will be the best for an application. Aesthetics is also a consideration. A small, two or three blade design might be best for a residential area, where a homeowner just wants to pull from the wind enough energy to power their own home, and would prefer a quieter option. A giant 12 blades design would not look very nice atop their home and would perhaps generate more energy than they need and likely more noise too!
Materials Early windmills were made of wood with canvas sails. These deteriorated over time and required care, but they represented the materials readily available! More recently, older mechanical turbine blades were made out of heavy steel but now many are made using fibreglass and other synthetic materials that offer strength at lower weights. And, lower weight building materials can result in larger blades to catch more wind applications where size and space are less of an issue. Manufacturers also use epoxy-based composites which may offer manufacturing advantages over other materials because the process has less impact on the environment and can result in a smoother surface finish. Carbon fibres have also been identified as a cost-effective method to further reduce weight and increase stiffness. Smaller blades can be made from light metals such as aluminium.
Engineers will be working in this field for years to come to determine the optimal shape weight, and materials to generate energy most efficiently! Learner Resource: Blade Innovation and Testing
Which Shape is Best? Turbines blades are made in many different shapes, and sometimes it is the application that determines which shape is the best. For example, a wind turbine blade design what researchers at Sandia National Laboratories developed in partnership with Knight & Carver of San Diego, CA promises to be more efficient than current designs. It should significantly reduce the cost-of-energy (COE) of wind turbines at low-wind-speed sites. Named “STAR” for Sweep Twist Adaptive Reactor, the blade has a gently curved tip, termed “sweep”, which unlike the vast majority of blades in current use, and is specially designed for low-wind-speed regions. The sites targeted by this effort have annual average wind speeds of 5.8 meters per second, measured at 10-meter height. Such sites are abundant and would increase by 20-fold the available land area that can be economically developed for wind energy. Sized at 27.1 meters long, it is almost 3 meters longer than the blades it will replace – and, instead of a traditional linear shape, the blade features a curvature toward the trailing edge, which allows the blade to respond to turbulent gusts in a manner that lowers fatigue loads on the blade. It is made of fibreglass and epoxy resin.
Research and Testing Before starting production of a new blade model, a prototype is tried out in a test bed. The blade is subjected to a strain corresponding to 20 years of operating during the testing process. LM Glasfiber is a good example of a “component” manufacturer – this is a business that does not manufacture an entire product but focuses on a specific component – in this case turbine blades. LM Glasfiber has produced a total of more than 120,000 wind turbine blades since 1978. This amounts to more than one in three of all the blades in operation today, worldwide. One of the company’s goals is to develop new technology that makes wind turbines more efficient and extends the service life of both the turbines and the blades. The company points out that “developing new types of blades is based on concrete decisions regarding design, materials and processes. Any adjustment to one parameter also impacts the others.” This means that if they test a new shape, the may need to change a material as well.
. Learner Worksheet: Design Your Own Windmill You are working as a team of engineers who have been given the challenge to design a windmill out of everyday items. Your windmill will need to be able to withstand wind from a fan for at least one minute while winding a string or wire to lift a light object such as a teabag. You are working on a budget and will have to “purchase” materials from your teacher to create your design. You may return materials, exchange materials with other teams, but will need to determine the “cost” of your windmill – the least expensive design that meets the challenge will be considered the most efficient design! Your windmill may be vertical (pointing upward from a table) or horizontal (pointing off the edge of a table).
Planning stage Meet as a team and discuss the problem you need to solve. Then develop and agree on a design for your windmill. You’ll need to determine what materials you want to use – keep in mind that your design must be strong enough to withstand from a fan or hairdryer and the base cannot move so it will have to be secured on a table or a shelf. Draw your design on the box below, and be sure to indicate the description and number of parts you plan to use. Present your design to the class. You may choose to revise your team’s plan after you receive feedback from class. Construction Phase Build your windmill. During construction you may decide you need additional materials or that your design needs to change. This is ok – just make a new sketch and revise your materials list and budget. Testing phase Each team will test their windmill using a classroom fan or hairdryer – each windmill will be tested using the same wind speed – medium – at a distance of three feet. You’ll need to make sure your windmill can operate for a minute at this speed while winding a light object up with a string. Be sure to watch the tests of the other teams and observe how their different designs worked. Evaluation phase Evaluate your teams’ results, complete the evaluation worksheet, and present your findings to the class. Use this worksheet to evaluate your team’s results in the “Working with Wind Energy” lesson: 1. Did you succeed in creating a windmill that operated for a minute that could lift an object? If not, why did it fail?
2. Did you decide to revise your original design or request additional materials while on the construction phase? Why? 3. Did you negotiate any material trades with other teams? How did that process work for you?
4. If you could have had access to materials that were different than those provided, what would your team have requested? Why? 5. Do you think that engineers have to adapt their original plans during the construction of systems or products? Why might they?
6. If you had to do it all over again, how would your planned design change? Why?
7. How did the most “efficient” design (the one with the low cost or budget) differ from your own?
8. Do you think you would have been able to complete this project easier if you were working alone? Explain...
9. What drawbacks does a wind turbine have as a reliable source of energy? What technologies exist that might compensate for these drawbacks?
10. What advantages does the windmill have as a renewable source of energy? . For Tutors: Alignment to Curriculum Frameworks for more formal learning Science Education (ages 4-9) CONTENT A: Science as Inquiry As a result of activities, all Learners should develop Abilities necessary to do scientific inquiry CONTENT B: Physical Science As a result of the activities, all Learners should develop an understanding of Position and motion of objects CONTENT E: Science and Technology As a result of activities, all Learners should develop Abilities of technological design CONTENT F: Science in Personal and Social Perspectives As a result of the activities, all Learners should develop an understanding of Science and technology in local challenges CONTENT G: History and Nature of Science As a result of the activities, all Learners should develop an understanding of Science as a human endeavour Science Education s (ages 10-14) CONTENT A: Science as Inquiry As a result of activities, all Learners should develop Abilities necessary to do scientific inquiry CONTENT B: Physical Science As a result of the activities, all Learners should develop an understanding of Motions and forces Transfer of energy CONTENT E: Science and Technology As a result of activities all Learners should develop Abilities of technological design CONTENT F: Science in Personal and Social Perspectives As a result of the activities, all Learners should develop an understanding of Science and technology in society Science Education (ages 14-18) CONTENT A: Science as Inquiry As a result of activities, all Learners should develop Abilities necessary to do scientific inquiry CONTENT B: Physical Science As a result of the activities, all Learners should develop an understanding of Motions and forces Interactions of energy and matter CONTENT E: Science and Technology As a result of activities, all Learners should develop Abilities of technological design CONTENT F: Science in Personal and Social Perspectives As a result of the activities, all Learners should develop an understanding of Natural resources Science and technology in local, national, and global challenges CONTENT G: History and Nature of Science As a result of the activities, all Learners should develop an understanding of Historical perspectives Technological Literacy – All ages The Nature of Technology Learners will develop an understanding or the core concepts of technology Learners will develop an understanding of the relationships among technologies and the connections between technology and other fields of study. Technology and Society Learners will develop an understanding of the cultural, social, economic, and political effects of technology. Learners will develop an understanding of the effects of technology on environment. Design Learners will develop and understanding of engineering design. Learners will develop and understanding of the role of troubleshooting, research and development, invention and innovation, and experimentation in problem solving. Abilities for a Technological World Learners will develop abilities to apply the design process. Learners will develop abilities to assess the impact of products and systems. The Designed World Learners will develop and understanding of and be able to select and use energy and power technologies. Learners will develop and understanding of and be able to select and use construction technologies.
You can find the Zero Carbon Britain 2030 report which explains how the UK can become 100% Renewable in the production of Energy here (download the first file): http://www.zerocarbonbritain.org/resources/cats-previous-zcb-reports Preparation and tutoring Wind Power in London, UK and Ploiesti Romania by Joanna Pinewood Education Limited February 2012 Wind power: Johnny Ionescu and Dan Petrescu produced, using Java, the following animation which can be used as a learning tool: www.danpetrescu.net/energy/wind.html It’s a simple animation were two variables can be changed. The blade sizes can be altered to assess power production. The wind velocity can be altered to assess power production. The results need to be written down in an excel spreadsheet and then a graph can be drawn. Comparison of variables shows the character of the wind turbine. As an example, compare blade sizes in multiples of 5m and you should make a table with the results below:
If you follow the above, you can with experience compare other multiples. The blade dimensions here are independent variable and the wind speed is constant (5m/s) and the dependent variable. Transfer the columns of information above to an excel spreadsheet. The one we used was Microsoft Office Excel 2007. To convert the table to a graph we used the following steps: 1) Select the data you need for the graph with the cursor; 2) Click on insert. This should show an assortment of graphs; 3) Click on “line graph”: in this example, we used a 2D line graph, it is the first to click; 4) You have now the graph on the spreadsheet; 5) You can select the data as functions of x (horizontal) and y (vertical) axis. You click right on the graph and you click “select data”; 6) For the horizontal axis, you can choose the variable data i.e. blade radius; 7) Click on “edit” in this column on the right of the window will appear the blade measurements. In the axis select the column you want in your table, in this case the blade radius. A dashed box will appear around the selected numbers and codes appear in the axis label range. Press OK, and the window “select data source” will appear again. 8) Then you have to select the y axis points. You need to deselect the x axis information in the column on the left of the window. “Blade radius” is shown in grey and you want to press “remove”. Click “remove” and that axis vanishes; 9) In the column showing “number of homes” and “energy” you can use the add button to select data from the same or other spreadsheets (here another variable can be added whenever you want); 10) If you click on the curve of the graph, that will highlight the column of results in the table; 11) If you wish to change or add labels or titles, click right over the labels. Using “chart tools” then “layout” you can change the chart title and axis titles. Click “axis titles”, then “horizontal axis title” then “title below axis”. A box appears on the graph, name your axis. For the verticals axis, click “primary vertical axis” and “secondary vertical axis” then choose how you want them to appear on your graph. Rename these axes. To choose a title click “chart title” and choose how you want it to appear. Rename in the title box; 12) If you have results of different units that you wish to appear on the same graph, you have to add a secondary vertical axis. To do this, click right on a series of the curve, and then select “format data series”. On “series options”, select “secondary axis”. Your graph is now ready. You can see just below the graph obtained with this procedure:
To enquire about the algorithm that produced the graphic, please email Daniela Ionescu Romanian project manager (daniprofa@gmail.com). If you wish to discuss other data and graphs you produce, please email headmaster@jpetutuors.com. |
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