New technique harvests electricity from nature's motions

From ANI

Washington, October 31: Duke University engineers have developed a novel approach that they believe can more efficiently harvest electricity from the everyday motions of the natural world.

Energy harvesting is the process of converting one form of energy, such as motion, into another form of energy, in this case electricity.

Strategies range from the development of massive wind farms to produce large amounts of electricity to using the vibrations of walking to power small electronic devices.

Although motion is an abundant source of energy, only limited success has been achieved because the devices used only perform well over a narrow band of frequencies.

"Nature doesn't work in a single frequency, so we wanted to come up with a device that would work over a broad range of frequencies," said Samuel Stanton, graduate student in Duke's Pratt School of Engineering.

"By using magnets to 'tune' the bandwidth of the experimental device, we were able verify in the lab that this new non-linear approach can outperform conventional linear devices," he added.

Although the device they constructed looks deceptively simple, it was able to prove the team's theories on a small scale.

It is basically a small cantilever, several inches long and a quarter inch wide, with an end magnet that interacts with nearby magnets.

The cantilever base itself is made of a piezoelectric material, which has the unique property of releasing electrical voltage when it is strained.

The key to the new approach involved placing moveable magnets of opposing poles on either side of the magnet at the end of the cantilever arm.

By changing the distance of the moveable magnets, the researchers were able to "tune" the interactions of the system with its environment, and thus produce electricity over a broader spectrum of frequencies.

"These results suggest to us that this non-linear approach could harvest more of the frequencies from the same ambient vibrations," said Brian Mann, assistant professor of mechanical engineering and materials sciences, Duke's Pratt School of Engineering.

"More importantly, being able to capture more of the bandwidth makes it more likely that these types of devices could someday rival batteries as a portable power source," he added.


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