Energy From Vibrations

JN writes "Now here's a nifty invention. What started off as a Small Business Innovation Research grant from the Navy to a MIT professor has turned out to become a great mechanism that harnesses running machines' minute vibrations into energy. The possibilities are limitless. Aside from the obvious, imagine the ultimate cellphone - one that charges the battery every time it rings/vibrates, hence promising extended talktimes, and giving operators all the more reasons to get their customers to use their devices. How cool is that? Do I see 3G applications with a vibrate() call mandatory every couple minutes? "

Comments

Re:This could be sweet.

[CmdrWass]

To paraphrase the parent post's comments:

A cell phone will use more energy to create the vibration than it will be able to regain from that vibration.

Due to the laws of thermodynamics and energy,(particularly the law that energy can neither be created nor destroyed), the device that generates energy from vibration would then (by definition) have to absorb some of the vibration's energy. Therefore, in order for this mechanism to "produce" any amount of valuable energy, the source (the cell phone) would have to increase its vibration. However, it will always be the case that the cell phone uses more energy than it gains back (otherwise the phone wouldn't vibrate). Therefore, it would be more condusive of the cell phone to focus its energy on notifying its owner of an incoming call, and do so in the most efficient way.

Basically, (as stated in the parent post) this invention at MIT doesn't do much for the cell phone industry. Cell phones would be better off being more efficient with the energy they have rather than trying to regain some of the energy expelled while producing environmental feedback.