Mobile Phones To Use Noise From Your Conversations To Charge Low Batteries

woman on cell phone photo

Photo by ElvertBarnes via Flickr CC

Using sound waves to charge small devices like cell phones is not a brand new idea. We reported on researchers from Texas A&M; and University of Houston working on just such a concept back in 2008. However, there is new research out that could bring us much closer to this futuristic idea. The Texas A&M; and University of Houston researchers focused on a certain type of piezoelectric material, which is able to convert energy when it is manufactured at around 21 nanometers thick. They had hoped to be able to perfect this material so that small disturbances, including sound waves, could be harvested for energy.

Now, the Telegraph reports that researchers from Sungkyunkwan University in Seoul, South Korea are moving ahead in devising other materials that could be used for the same purpose.

Dr. Sang-Woo Kim states, "The sound that always exists in our everyday life and environments has been overlooked as a source. This motivated us to realize power generation by turning sound energy from speech, music or noise into electrical power."

Anyone living in a busy urban environment can attest to the amount of ambient sound that feels intensely annoying...unless it could be used for a purpose. The new technology is baded on using strands of zinc oxide layered in between two electrodes, reports the Telegraph. On top of the electrodes is a sound-absorbing pad, which vibrates when sound waves hit and causes the zinc oxide wires to compress and release, creating an electrical current. Tests of the technology show that 100 decibels of sound can generate 50 millivolts of electricity.

"Sound power can be used for various novel applications including cellular phones that can be charged during conversations and sound-insulating walls near highways that generate electricity from the sound of passing vehicles," states Dr. Sang-Woo Kim.

So not only could noise from cell phone conversations be harvested, but so too could car noise be absorbed and put to use.

Of course, putting up sound-insulating walls along highways would be an incredibly expensive proposition for a municipality. The amount of energy harvested would have to be significant to justify the cost -- a whole lot more than 50 millivolts.

We often look at cool ideas for renewably powered cell phones and other small devices, but we just as often have to ask: is it realistic? For some technologies, the costs and trouble simply don't justify the resources and effort that go into generating a little bit of energy. For now, this is the case with sound harvesting -- with "for now" being the operative phrase.

The researchers are still working on the technology, but the sustained interest in harvesting energy from sound shows us that we very well could will one day have cell phones and other devices that are charged as we simply walk down the street.

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