WOW!!!!! I am impressed a mere 30DB below the threshold of pain and the device can generate perhaps a milliwatt of power. Yep, definitely another green energy triumph.

WOW!!!!! I am impressed a mere 30DB below the threshold of pain and the device can generate perhaps a milliwatt of power. Yep, definitely another green energy triumph.

It's in its early development. If it can generate energy from sound, perhaps it could generate energy from the vibrations of a vehicle on a road? Or a bicycle? With some research, in 5-10 years time it could be considerably more efficient, and cheaper.

perhaps it could generate energy from the vibrations of a vehicle on a road

While at the same time being able to collect sunlight? Hardly any of the vibration energy reaches the exposed surfaces of a car for a good reason: the occupants of a vehicle would go deaf from the noise if there was such vibrations in the chassis.

It's very hard to imagine a situation where sunlight would alternate with a 100 decibel noise or other vibration. Well, except for certain vulgar scenarios.

Were a vehicle to generate this much noise energy, we could acquire far more energy savings by addressing the waste of energy at the source than you could ever recover by recapturing, converting and storing that lost energy.

Forget putting it on a vehicle. instead just have a series of collection devices by train tracks or runways or even on the side of the road? Then port the energy to storage devices or to the grid. We could recover so much of the wasted energy we now "throw away".

Couple of years ago, when these nanopiezo actuators were first reported, I went to our national institute for earthquake monitoring(which just happens to be 150 meters down the road) and had a bit of a chat with them.
Got some data on the natural background vibration of the Earth (microearthquakes, which are going on all the time)...
Was surprising for them as they usually only study large earthquakes.

The intent was to find out if one could harvest the energy of those microearthquakes efficiently (simply by making a power spectrum and looking at how much energy would be contained in the best suited frequencies)

Turns out the energy content is too low to be of much use in large scale applications (i.e. power generation in general). But there still are scenarios where this can be useful, like embedded sensors that harvest energy over time, e.g. charging a capacitor, and then use that power once every day or so to transmit a burst of data.

WOW!!!!! I am impressed a mere 30DB below the threshold of pain and the device can generate perhaps a milliwatt of power. Yep, definitely another green energy triumph.

Glad you're impressed. Since you sound like you really know what you are talking about, I'm curious how you calculated that one milliwatt figure?

WOW!!!!! I am impressed a mere 30DB below the threshold of pain and the device can generate perhaps a milliwatt of power. Yep, definitely another green energy triumph.

Glad you're impressed. Since you sound like you really know what you are talking about, I'm curious how you calculated that one milliwatt figure?

Your right, I just guessed. It could be a just few microwatts. One thing is for sure, if it was a substantial amount of power, say enough to power a LED they would have mentioned the power output of the device. Power is a much more meaningful parameter than voltage.

I have to say one positive thing about this. It is the first product that is able to harvest energy from the dying screams of it's bankrupt investors.

This whole thing is actually very similiar to the physics problem of how long would you have to shout at a cup of coffee to heat it up.

Sound intensity at 0 dB is 10e-12 W/m^2. Let's assume that we're measuring 100 dB at 1 meter distance from the source. 100 dB intensity is 100 mW/m^2 and the surface area of the unit sphere is 4 pi, so we got a sound source that outputs approximately 1.26 Watts of acoustic power. To harvest, or at least absorb, all that power would require 12.6 square meters of material surrounding the source at that 1 meter distance.

So that explains why they're only getting microwatts of power out. There's really very little power to harvest in the first place.

That's right - you don't need a whole lot of power to make loud sound. The reason why big loudspeakers need more of it is because you're not listening at 1 meter distance, and because ordinary speakers are really really inefficient at turning electrical power to sound.