Paper or plastic bottle wind turbine
Blades cut from a bottle spin a small DC motor that works as a generator and lights an LED.
The big idea
Wind pushes on blades and turns them. If the blades spin a motor, the motor makes electricity. This model shows the same idea as a full-size wind farm.
You will need
Tick things off as you gather them.
Step by step
-
Step 1: Cut the blades
Cut the bottle into a cylinder and slice it lengthwise into four to six strips about 4 cm wide. Round the tips. Each strip is one blade.
-
Step 2: Make the hub
Push a hole through the bottle cap that fits the motor shaft. Glue the base of each blade to the cap, all at the same angle, like a fan.
-
Step 3: Fit the motor
Push the cap onto the motor shaft. Tape the motor to the top of the pole so that the blades face the wind.
-
Step 4: Add the LED
Connect the motor terminals to the LED legs with wires. If it does not glow when you spin the blades, swap the legs round.
-
Step 5: Test in the wind
Hold the turbine in front of a table fan on a low speed, then a higher speed. Or take it outside on a breezy day. Watch the LED.
-
Step 6: Change one thing at a time
Try three blades, then six. Try flat blades, then curved ones. Try a steeper angle. Change only one thing each time.
-
Step 7: Record your results
Make a table of blade shape, blade count and LED brightness. Which design made the best light?
What to look for
- Faster wind makes the LED brighter.
- Curved blades usually catch the wind better than flat ones.
- More blades is not always better. Too many can crowd each other.
Why it works
A motor has magnets and coils of wire inside. Run electricity in and the shaft spins. Spin the shaft and, the other way round, electricity comes out. That is a generator. When the wind turns the blades, it turns the motor shaft, and the moving coils inside make a current that lights the LED.
Try this next
- Make the blades longer and see what changes.
- Use your anemometer from the wind speed experiment to measure the wind.
- Add a second turbine and wire the two in series.
Stay safe
Keep fingers and hair away from the spinning blades. Ask an adult to cut the bottle.
Link to the grid
Wind farms use this same principle. The blades are 60 metres long, and the generator feeds the grid instead of an LED.
Learn how the grid worksMore wind, water and muscle experiments
Water wheel generator
Spoons or bottle caps on a wheel catch falling water and turn a motor to make electricity.
Pedal-powered generator
An old bicycle turns a DC motor to light bulbs and shows how much effort electricity takes.
Bicycle dynamo lamp
A cheap bike dynamo lights an LED. A great way to see how a generator works.