What the Wind? Edit
The Overview of Wind EnergyEdit
A. Wind Energy
Over the past decade, wind energy has grown significantly as people are considering it to be a viable energy alternative for the future. ( http://www.gwec.net/global-figures/wind-energy-global-status/) Most people, however, do not understand how the easily recognizable windmills generate energy. In order to make an informed decision about whether the nation, as a community, should invest in wind energy, each individual must first grasp how this simple concept actually functions. This section will introduce the reader to the workings of a wind turbine, and later sections will consider the future of this emerging energy field.
B. How It Works
Wind energy utilizes natural wind for the purpose of generating energy through the rotation of a wind turbine. Wind spins the blades, blades spin a central shaft, the shaft runs a generator by utilizing gears, and electricity is produced. http://energy.gov/eere/wind/how-do-wind-turbines-work
The shaft does not rotate at adequate rpm to produce electricity by itself. As such, the gears are used to increase the rpm to approximately 1800 resulting in a significant amount of electricity.
(Image taken from: http://www.epa.gov/climatestudents/solutions/technologies/wind.html)
Wind turbines come in many sizes, but for the purpose of generating energy, industrial wind turbines are quite large. In one popular model, the tower that supports the turbine is 212 ft, and the blades that spin are approximately 116 ft. In the same model, the size of the circumference of air that one revolution sweeps is just below 1 acre. https://www.wind-watch.org/faq-size.php
Location is a vital concept to understand when considering wind energy because wind turbines do not adequately function in every geological terrain. Wind turbines are most productive when in the ideal windy location. Such a location usually consists of a high elevation, coastlines, or a flat plain in close proximity to a mountain. http://www.windsolarenergy.org/map-of-best-locations-for-wind-power.htm
The Benefits and Drawbacks of Wind Energy
Just like any alternative energy source, there are pros and cons of Wind Turbines. Some of the more positive aspects of using wind turbine energy as an alternative energy source are:
- · Clean source of energy
- · Fewer environmental impacts: doesn’t release emissions that pollute air or water
- · Does not require water for cooling
- · Reduces the amount of electricity generated from fossil fuels and therefore reduce the amount of air pollution, carbon dioxide emissions, and water use of fossil fuel power plants
- · Small physical footprint relative to the energy it can produce
- · Usually on farm or ranch land, which earns owners extra income
- · The potential of wind power is enormous – 20 times more than what the entire human population needs
- · Renewable energy and no way to run out of it
- · Space-efficient (largest turbine powers 600 US homes)
- · Only accounts for 2.5% of total worldwide electricity, but is growing 25% per year
- · Prices have decreased over 80% since 1980; operational costs are low
- · Protects homeowners from power outages
- · Harnessing wind energy can be done almost anywhere, though some places are much better than others
Some of the more negative aspects of using wind turbines as an alternative source energy are:
- · Very large machines and makes a visual impact on the landscape
- · Machines can be noisy
- · Though rare, some have leaked lubricating fluids
- · Some types have killed birds and bats/affecting their habitat
- · Require service roads, adding to cost and impact
- · Making the wind turbines and its foundation requires energy possibly from fossil fuels
- · Fluctuating source, it can’t become a primary source unless some form of energy storage is used
- · Heavy upfront costs
- Not all locations produce sufficent wind to produce sufficent energy (though wind itself is everywhere)
The Cost Effectiveness of Wind TurbinesEdit
Research shows large wind turbines, compared to small wind turbines, have larger energy output. Larger wind turbines produce power to utilities from a range of 250 kilowatts to 3.5 to 5 megawatts, while smaller wind turbines that possess a smaller horizontal axis design reach a power production of 250 watts to 50 kilowatts. Larger wind turbines, therefore, are most cost effective. The total production cost per kilowatt hour of electricity produced has generally decreased with increasing wind turbine size. The most costly projections in the future will be related to cost-effective material systems, manufacturing and upkeep.
Relativity to Class ContentEdit
Kinetic energy, generators, power, electricity and frequency are topics that undergird the principles of wind energy.
The term wind energy describes the process by which wind flow, or motion energy, is used to make electricity. The output of electricity from wind turbines is produced when kinetic energy in the wind enters into the shaft of the wind turbine and converts the wind into mechanical power. The generator, a part of the wind turbine, converts the mechanical power into electricity. The coils in the generator rotate to create a flow of electrons. The faster the rotor and shaft rotate, the more electrons are produced, reaching the electrical grid.
The small increase in wind speed is directly proportional to power output. The frequency at which wind travels consistently to power the blades of wind turbines is equal to the power output and production of electricity. The variability of wind energy is not necessarily reliable; therefore, the frequency of the wind speed to create electricity is constantly increases and decreases.
To test the effectiveness of wind turbine energy, we created our own wind turbines out of household marterials and tested their effectiveness against each other. We kept the same base and axel but tested four different rotors (the mobile portion of the wind turbine) made out of standard printer paper, cardstock, aluminum and duct tape. We tested the effectiveness of each rotor by timing the speed it could wrap a washer attached to a strong around the axel of the turbine. The faster the string and washer wrapped around the axel, the more powerful the rotor design was. Through this experiment we tested the hypothesis that: 'Aluminum is the most effective material for making a homemade wind turbine".
Independent Variabe: Wind turbine material
Dependent Variable: Time it takes for the turbine to wind up the washer
Control variable: same wind speed, fan same distance away, same rotor dimensions
Contants: Same base and set up each time
Preliminary Steps: The following two steps are best done prior to class for the safety of students.
1. Empty one 500mL bottle of water and let stand and dry completely. Empty one 1L water bottle and let stand dry completely. Both water bottles must be completely dry before beginning the following procedures.
2. Drill two small holes in 1 500mL of water. One hole is drilled through the cap of the water bottle and the other hole is drilled directly in the bottom of the bottle.Procedure:
3. Cut two U-shaped semi circles directly across from one another on the 1L water bottle. This will leave two sides on the water bottle directly standing to hold the 500mL water bottle horizontally. The 500mL water bottle will sit perpendicular (on its side) in the holder created by the two cuts.
4. Fill the 1L bottle with 50 marbles.
5. Set aside 18 of the non-bendable straws that will be used to make 4 axels total. The axel will form a “T” shape. The base of the T is comprised of 2 ½ straws and the top of the T is comprised of 2 straws. The straws best fit together using scotch tape.
6. Cut 8 8cm x 10cm rectangles total. Two rectangles will be cut per each material and will act as rotors in the experiment (i.e., 2 rectangles per printer paper, 2 per cardstock, 2 per aluminum sheet, 2 per duct tape).
1) For the purposes of this experiment, we modified the paper material by adding a cross-shaped “T” on the paper using unwound paper clips. The paper clips act as a support for the paper material against the wind to increase the surface area.
2) The duct tape material may also need modification, based on individual discrepancy.
7. Next, tape each set of rotors (2 per set) on the opposite ends of the “T” shaped axel. The rotors are equal in distance from one another because the straws are equal in length. There should be a total of four different wind turbines created from this step.
8. Fit the axel through the drilled holes in the 500mL water bottle. The end of the axel will stick out from the end of the water bottle, and the rotors will stick out from the top of the water bottle. Rest the 500mL water on the 1L water bottle with the axel in place.
9. To create the washer attachment, which will be used to measure the efficiency of the wind turbine, cut half of a straw and tape a paper clip partially opened to the end of the half straw. Cut an 18cm piece of string and tape one end of the string to the paper clip and tie the other end to the washer.
10. Set the fan, which will act as the source of energy to generate the wind turbine, 52 cm from the wind turbine.
11. The experiment is ready and fully prepared. Set the fan on wind speed 3 (or the maximum wind speed which will most effectively propel your wind turbine depending on your fan).
12. Use a timer to conduct three trials to gain the average of each set of rotors. To begin the experiment, designate one person to switch the fan “on” every trial, and designate a timer for the experiment. The timer and fan should start at the same time. Steps 8 and 9 will need to be repeated throughout the experiment until each set of rotors has been tested.
13. Collect the data and average gathered from the wind speeds of each set of rotors.
14. Make accurate conclusions based on results.
After running three trials for each rotor with some minor adaptations, we collected our results. We measured the winner by the lowest time it took the rotor design to wrap the string and washer around the axel. Overall, the cardstock was the clear and consistent winner. It had the lowest average of the times and the most reliable performance. Throughout our experiment we ran into multiple obstacles involving the initial take off of the turbines. The paper rotor would not operate without an adaptation of the paperclip and the duct tape would not operate at all, even with additional adaptations. Obviosuly, in a real life sitaution, the turbines would be made of more durable and stiff materials and so this exact obstacle may not occur but we did recognize that in building a real turbine there would be a heavy revision process, as we experienced.
After taking these things into consideration, we recorded and graphed the data.
|Paper and paperclip||Cardstock||Duct Tape||Aluminum|
The table above represents the raw data from all of the trials we ran with the multiple rotors.
The table below represents the data organized in the form of a bar graph
If you read above, you'll notice that the cardstock not only had the lowest times of all the materials but it also had the most consistent time trials.
After recording and interpreting our results we concluded that our hypothesis was incorrect. Aluminum foil turned out to be less structured than we anticipated and therefore did not carry the windpower of the fan as effectively. Cardstock was actually be the best material for rotor design because of it's consistency and it's strength. In the trials, we also observed that a large portion of the time recorded in the trial was the "start up" time for the rotor. After the initial rotation, the speed of the cardstock's rotation and performance increased exponentially.When thinking about using wind as an energy source, consistency is always an issue to take into consideration. We came to the conclusion that the cardstock would be our most effective rotor design because of it's consistent and speedy performance after the initial rotation for the rest of task. We also concluded that in designing a real wind turbine that the post-start-up performance would be the biggest indicator of long term success and effectiveness even if a shorter time trial was recorded for another material.
Our Opinion: The Future of the Wind TurbineEdit
The future of the wind turbine is continuing to look more promising all the time. These structures are becoming more of a reality in the Great Plains of the United States and in states like Iowa and Texas especially. Since wind turbines are one of the cheapest and environmentally friendly sources of energy, they are one of our most promising options for the future. In looking forward, we can probably count on this industry growing into more of a normal part of our economy and our lives. Despite its drawbacks, we think wind energy is definitely worth looking into as an alternative energy source for the future.
Skill#1: Where are wind turbines located?
Skill#5: What are some potential problems arising from the use of wind energy/ wind turbines?
Skill#3: How energy is created from the spinning of wind turbine blades?