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In this issue:
Pinwheel Wind Turbine
Make a pinwheel to see how a very basic turbine works, and then use it to create electricity! If you don't have the electrical components, you can still do the first part of this project to see how wind can create mechanical force.
What to do:
Part 1 - Pinwheel
Part 2 - Generator
When you attached the motor to the pinwheel and put it in front of the fan, you transformed the motor into a generator, which converts mechanical force (the spinning of the pinwheel) to electricity. It does this with the help of a magnet inside the motor. When you connected the wires of the motor to the light bulb, you made a complete electrical circuit, allowing the electricity to flow from the motor through the bulb and back again.
One way to measure power is in volts. A volt measures the amount of electricity flowing through a circuit. The faster a generator spins, the more volts it will produce. With our simple wind turbine, a smaller pinwheel will produce more volts because it can spin faster. To fully power the bulb, your turbine would need to produce 1.5 volts. If the bulb just glows dimly, it means the turbine is producing less than 1.5 volts.
Real wind turbines have very large blades, so they have gear boxes that increase the rotational speed (how fast the shaft spins). For example, the main shaft might turn only 22 times per minute, but the gears in the gearbox can use that power to make a smaller shaft turn up to 1500 times per minute, creating a lot more voltage!
More experimentation: If you have a digital multimeter, you can measure the amount of voltage and current (amps) produced by your mini turbine. Experiment with larger or smaller pinwheels, or make individual blades like a modern wind turbine. Which design can produce the most voltage? Which produces the most amperage? When would you want more amps and when would you want more volts? What size of pinwheel causes the light bulb to glow the brightest? Can you use your turbine to power another motor? To lift weights?
Strange as it may seem, wind energy comes from that ultimate power source, the sun. (In fact, almost all sources of energy originate with the sun!) As the sun shines on the surface of the earth, it heats the land faster than the oceans. The warm air above the land rises, and when it does so cooler air from over the water rushes in to take its place--this is wind! Meanwhile, the rising hot air cools and descends back down over the water. This air circulation is called convection. You may wonder how you have wind in your area if you don't live by the ocean. Convection is happening on a huge scale throughout Earth's atmosphere, so it doesn't just affect the coasts.
Since wind energy is a renewable resource and does not produce any pollution, it is a good alternative to fossil fuels. A wind turbine can produce enough electricity in about 6 months to recover the amount of energy used in building it, although it takes much longer than that to pay for itself. In the US, the production of electricity by wind is increasing by up to 50% per year, as more wind farms are built. Countries like Denmark are producing close to 20% of their electricity needs from wind power. While wind energy is a great supplemental energy, it is unlikely to become a primary energy source due to limitations on where turbines can be built and the unpredictability of wind.
More Alternative Energy Projects:
- The largest wind farm in the world is located in Texas, with 421 turbines. It produces enough energy to power 220,000 homes.
- The amount of energy a turbine can capture from the wind depends on how large the rotor is. If you double the size of the rotor, you will quadruple the amount of energy captured!
Find out what it takes to set up a turbine with this National Geographic special. Use the tabs to see video and photos.
Learn about the power grid with this interactive diagram and PDF lesson.