Acoustic Energy Harvesting - Making Energy Sector Sound

Acoustic energy is the energy of the sound waves while traveling through a medium. Though we hear pure sound but some energy is associated with those sound waves and hence the name “Acoustic energy”. Jeong Ho-You, a mechanical engineer in Dallas at the Southern Methodist University wants to tap this energy with the help of tiny resonating chambers and convert it into a low-amperage current so that it can be used in some of the electronic gadgets. He has made a computer based simulation model of the chamber and will be presenting it at the Acoustical Society of America in Seattle next month.

#-Link-Snipped-#The problem with the sound energy is that it has a low energy density. Mark Sheplak, a mechanical engineer at the University of Florida, in Gainesville estimates that: The sound of a crowd in full roar at London’s Wembley Stadium would provide only enough energy to fry an egg. (IEEE Spectrum). Using a Helmholtz Resonator, Sheplak’s team extracted about 30mW of energy in the laboratory. It consists of a cylindrical assembly which lets in the sound from the hole at one end and develops an oscillatory pressure in the cavity. A small piezoelectric plate or diaphram is kept at the other end which vibrates as the pressurized sound waves strikes the diaphram and generates a small amount of electric current.

But You has some different ideas for his project. He is using a piezoelectric beam along the length of the cavity so that more energy can be captured. This is harvesting using “Sonic Crystal”. A rod is removed from a perfect sonic crystal in order to create a point defect. This acts as a resonating cavity and the piezoelectric beam can be localized easily.

The methods may be different but the intentions are the same. If a safe and successful laboratory process is developed, it will benefit a huge number of ordinary people in day to day life. Though the process cannot replace the entire battery of a cell phone but increasing the battery life can surely be thought of.