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Lessons blowing in the wind

Modified: Friday, May 11th, 2012


SDSU graduate student John VerSteeg explains to a Mickelson Middle School seventh-grader how the 400-watt wind turbine to be installed at the school will work. VerSteeg and grad student Christina Gerometta presented wind turbines to Mickelson’s Technology Education classes Wednesday. Charis Prunty/Register


• Brookings middle school students using wind energy in the classroom

BROOKINGS – When the Brookings School District’s 400-watt wind turbine gets installed at Mickelson Middle School soon, some students there will already know quite a bit about how it works.

Wednesday, seventh-graders in Dell Poppinga’s Technology Education class had a visit from members of the South Dakota Wind Application Center (SDWAC), based at South Dakota State University.

Today, SDWAC will lead Mickelson eighth-graders in a workshop where students work with various shapes of turbine blades, to see the different effect of each.

Graduate students John VerSteeg and Christina Gerometta explained many engineering factors used by wind turbines Wednesday afternoon in Poppinga’s class, then allowed students to try out the small turbines they had brought with them.

The class, a hands-on approach to exploring STEM topics, had already studied conservation of mass. Conservation of energy is the same, VerSteeg said, in that energy can’t be created or destroyed – only converted from one form to another. A wind turbine, he said, is converting fluid energy (wind, a gaseous fluid) to electrical energy.

“Wind comes at the turbine blades and causes them to turn,” he said. “That converts the fluid energy into mechanical energy, and then the turning blades turn a generator inside of the wind turbine, which converts mechanical energy into electrical energy.”

The process is similar to flight, VerSteeg said, but while an airplane converts thrust to lift and drag, a wind turbine begins with lift and drag and converts that to thrust.

The turbine uses Newton’s law of “action necessitates reaction” to make its blades spin, VerSteeg said: Blades are angled so that, if they catch wind on the left, it will bounce back to the right and that movement will turn the blades. Pressure changes are also a factor in creating spin, he added.

“How quickly do the blades spin?” a student asked. VerSteeg said that’s tricky, because they need to move fast enough to produce power but not so fast as to break themselves, or to break the sound barrier.

“The tip of the wind turbine blade is designed to go just under the speed of sound, because if you broke the sound barrier it would make a lot of noise, and that’s one of the biggest complaints about wind turbines, is that people don’t like the noise,” VerSteeg said. “So, there’s a lot of effort that goes into trying to make them quiet.”

“But, the wind turbines, the ones out in the field, they go 18 revolutions per minute,” Gerometta added, speaking of the entire blade. “So, it only goes one revolution every few seconds, but the tip is a lot faster.”

The class also discussed how many turbines South Dakota has now (700-800, VerSteeg estimated), why engineers design multiple smaller turbines rather than one giant turbine, whether we have the technology to store excess power from these turbines, and even why they are usually white. The color is to keep them from overheating, Gerometta and VerSteeg said, and also to help them blend in with the sky.

Gerometta said engineers at the South Dakota Wind Application Center use tools to determine where wind turbines should be placed and how large those turbines should be. They brought with them Wednesday the actual turbine to be placed at Mickelson – a 400-watt turbine to be mounted on a 29-foot tower.

That turbine won’t produce much power – just enough to light about four light bulbs – but it will be a learning tool for students throughout the district. Poppinga said he anticipates exploring engineering and physics principles used by the wind turbine a few times a year, for his Technology Education class. The class already covers 15 modules, spending seven days per module. In the Plastics and Polymers module, for instance, students learn about the conservation of mass as they form golf tees and other plastics. In the Flight Technology module, they learn basic engineering and aerodynamics principles that helped with the wind turbine discussion Wednesday.

“The nature of this class is all hands-on, so they learned about (turbine engineering) a little more today and then they got some more hands-on experience with it,” Poppinga said.

Following the discussion, students were welcomed to spin the blades on the 400-watt turbine and use a fan to spin those on smaller models supplied by the Wind Application Center, to test the process for themselves.



Contact Charis Prunty at cprunty-@brookingsregister.com.












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