In many places, wind power is getting to be a big deal. Already by last year, some 4.7 percent of all U.S. electricity came from wind turbines. Farms of these wind-power devices are spreading across the planet. And some are becoming true giants. The largest are taller than 60-story skyscrapers. Just one can produce enough electricity to power more than 1,500 homes.
But some researchers are bucking this trend. They’ve chosen to go small for uses that are also tiny. For instance, a small-scale windmill might be all that’s needed to run a single sensor that will only gather some type of data once every few minutes, if that often.
Such low-cost generators could be particularly useful in remote spots, where it would be too expensive and troublesome to run power lines. Or they might replace batteries that would run down and then need frequent recharging or replacement.
And professional researchers are not the only ones trying to develop these devices. Two of this year’s Broadcom MASTERS finalists are also working to harness wind power for these tiny needs.
MASTERS stands for Math, Applied Science, Technology and Engineering for Rising Stars. The Broadcom MASTERS competition brings together 30 middle-school students each fall. The program was created by Society for Science & the Public, which publishes Science News for Students. Broadcom Foundation sponsors it. Part of the competition is based on research the students entered the year before in a science fair.
Harnessing the wind
There are many sorts of sensors that can operate on low power, explains Heath Hofmann. He’s an electrical engineer at the University of Michigan in Ann Arbor. That’s especially true for sensors that operate only infrequently, he notes. “Scientists are still trying to figure out all the possible uses there might be for such sensors,” he says.
Some researchers have used low-power sensors to monitor wildlife or environmental conditions on the seafloor. Others use such sensors to monitor the vibrations of bridges as traffic passes across them. Changes in those vibrations over time, he notes, could signal that parts of the bridge have worrisome cracks that are growing in size. Still other engineers have proposed using remote sensors to scout signs of corrosion in energy pipelines.
Before anyone can rely on such sensors, however, they’ll need a power source such as the tiny systems being developed by this year’s Broadcom MASTERS contestants.
To create his, Akhilesh Balasingam, 13, of San Jose, Calif., used a piezoelectric material. When such materials flex, electrons inside them move to generate an electric current. (The “piezo-” prefix comes from the Greek word piezein. It means “to squeeze” or “to press.”)
The teen glued a strip of the material roughly 2 centimeters (about an inch) long to a flexible strip of brass. Then, he stuck a tough plastic weight onto the end of the metal strip. Finally, he hung that strip from the underside of a board so that the weight could swing back and forth like a pendulum whenever the wind blew. That motion caused the piezoelectric material to bend and flex. This created a small amount of electric current.