Fun with Less Kilowatts: Build a Wind Turbine

By Vernon Trollinger, June 12, 2017, Family

Yes! It actually does generate electricity!

Welcome to Fun with Less Kilowatts! We believe that science experiments at home can be a creative way to engage kids in learning while having fun. They can be educational AND great activities to keep your kids busy and away from the television. Each month, we’ll feature a new science experiment that can be a great resource for parents and teachers.

Build a Wind Turbine

Kidwindrob posted a fun tutorial on Instructables.com about how to build your own wind turbine using a small DC motor and your own fan blades, mounting the whole thing on a PVC pipe frame work. Like their much, much bigger cousins, these little wind turbines generate power in much the same way. The wind blows against the fan blades and causes the fan assembly and axle to rotate. The axle is connected to a dynamo which generates Direct Current (DC) as it spins.

Real wind turbines that make electricity out in west Texas are mounted on towers that rise as high as 260 feet. The turbine blades are each about 100 feet long. The turbine is connected to a dynamo inside a bullet-shaped housing called a nacelle. These full sized turbines generate over 200 megawatts of electricity.

DC motors not only spin when you connect them to DC electricity but they can also generate electricity when you spin them. By connecting the motor shaft to a set of fan blades attached to a central hub you can make a wind turbine.

A note on DC motors

The problem, however, is that small DC motors need to spin fairly fast to put out a measurable amount of power. Gear boxes can improve speed but in this experiment we’re not using one. Because wind speed isn’t all that fast, the trick is to find a DC motor that will put out a measurable amount of electricity at low RPMs. Unfortunately, these can be hard to find at hobby shops and hardware stores but they can be ordered online.

For our little wind turbine, the motor I had handy was a DC motor (rated approximately 18 volts) from an HO scale model engine, an Athearn “Blue Box” type which can be found on eBay for under $10. I knew this motor could generate some current if the shaft was directly connected to a turbine —but I didn’t know how much. So, I thought it would be fun to find out.

The Materials

  1. One DC motor with good voltage output at low RPMs.
  2. Some incandescent Christmas lights — although LEDs would work, incandescents will dim and brighten as the voltage changes.
  3. Wire leads with alligator clips
  4. A multimeter to measure voltage.
  5. 1 inch diameter PVC elbow and a short straight section. This will work as the nacelle to house the DC motor.
  6. Wire. About two to three feet of 16 AWG gauge will be fine.
  7. Fan blades — makes these out of stiff cardboard. Cut these to about 12 inches. Any longer and they will be too heavy for the hub to hold. If they’re too short, they won’t grab enough wind.
  8. Three 1/4” wooden dowel rods. These were cut to 12” lengths and one was hot glued and taped to the back of each fan blade.
  9. A fan blade hub. I used a 3/4” piece of PVC pipe. This was drilled in three evenly spaced places with a 1/4” bit to hold the dowel rods on the fan blades. Use plenty of hot glue to secure the dowels in the hub together.
  10. Fan tower — while Kidwindrob detailed the building of a base for the wind turbine, I stuck my nacelle on top of an 18” tall 1 1/2” piece of PVC pipe and wedged it into a cement block for testing. If you do decide to build a base for a more complete wind turbine, consider filling the empty PVC at the bottom with sand to act as a weight to help keep your turbine upright.
  11. An electric fan — to test your wind turbine.

The Directions

  1. Make the wire connections to your DC motor and secure them with black electrical tape. Thread your wires out from the nacelle so that it is most convenient for you.Fit the motor into the nacelle so that is firmly seated and snug.
  2. Spinning blade exerts a lot of torque on the motor and if it is not secure in the nacelle the spinning will work the motor loose.

    Fit the motor into nacelle so that it’s firm and secure in place.

  3. Attach nacelle to top of fan tower. If you are using PVC, this might not need to be glued as long as the connection is firm.
  4. Make wiring connections. Either clip your alligator leads to the incandescent Christmas lights or to your multimeter.

Assemble the fan blades.

  1. Fan blades can be made almost out of anything but do not use material that can have sharp edges.
  2. Make the fan hub. Cut a 1 inch long piece of 3/4 PVC pipe. Drill three holes evenly spaced from each other around the circumference of the pipe.
  3. Attach the dowels to the back of the fan blades with hot glue and tape. Leave 1/2” of dowel extending beyond the fan. This is to fit into the hub.
  4. Insert each dowel end of each fan blade into the PVC fan hub. Secure with plenty of hot glue.
  5. Attach fan hub to DC motor shaft. In my case, I was able to hot glue the hub directly onto a brass flywheel on my Athearn motor. Different motors and shaft sizes will require different connection methods.

Now—turn on the fan and face your wind turbine into the rushing air!

The Result

As the turbine spins, the incandescent Christmas lights will glow or you’ll get a voltage reading on your multimeter. You’re generating electricity!

My old Athearn motor only produced a puny .16 volts DC.
Using the right motor will produce better results!

The Science

DC motors are made of an armature coil attached to the motor shaft that is surrounded by magnets that don’t move. As the wind turbine spins the DC motor shaft, the motor’s commutators and armature coils rotate within the magnetic field of the stationary magnets. This movement creates an electrical current to flow from the motor. The faster the rotation, the more electricity that generated.

Want to know more and do more with wind turbines? Check out the KidWind Challenge to see wind turbines made by kids that really crank out power!

Do you have any fun and kid-friendly science experiments you’d like to see us try for Fun with Less Kilowatts? Share with us in the comments!

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About 

A native of Wyomissing Hills, PA, Vernon Trollinger studied writing and film at the University of Iowa, later earning his MA in writing there as well. Following a decade of digging in CRM archaeology, he now writes about green energy technology, home energy efficiency, DIY projects, the natural gas industry, and the electrical grid.

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