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By bob12
I know it's not a new invention and most of us know how it works to act as transducer between air pressure (ie sound waves) and current. But the idea behind it is always to capture intelligible sound.
The idea that I propose is based on the same scheme as microphone but for the purpose of generating electricity. We can think of huge or array of microphones installed near noisy or windy places to perform like windmill but at very low cost.

Reward: mark of gratitude
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By Steve
Interesting idea! ;-D I would assume though that in a microphone, the electricity isn't actually generated, rather the sound is translated to current by the input of even more electricity? :-?
By Rishi
A moving coil mike can generate power. A few years back 'The New Scientist' magazine gave the snippet that the total energy of a senior professor's annual speech output was equal to 5 US cents worth of electric power!
I doubt if there will be any worthwhile return on investment from electricity from sound.

An interesting concept all the same.

By The_Wise
Awesome..I never thought of that! Of course, sound is energy much like a swell of water. I like it, definately a good way of generating power at a construction site!
By MissPlayful
I agree with Rishi - I don’t think sound waves at the kinds of noisy sites you are referring to would carry enough energy to generate economically useful amounts of electricity for everyday situations. But there are probably situations where small amounts of electricity generated from sound would be of value to scientists.

Your idea nevertheless raises an interesting question and suggests possible lines of research. Are there ways other than windmills to generate electricity from wind? We know that some things can vibrate in the wind - leaves for example, and tightly strung wires. Instead of trying to convert the sounds that such vibrating objects make into electricity, could we build generators that make electricity more directly from large vibrating metal or plastic ‘leaves’ or arrays of vibrating metal strips or wires set out in the wind? Maybe we could design objects into optimal shapes for converting a large proportion of the wind energy that flows around them into vibrations rather than rotations, and then we channel those vibrations into our generators.
By sevenizm
Hey that's hot. Place microphones all over the city. At the beaches (waves hitting rocks). Have all that power put into some sort of battery. By itself it may not mean anything, but in conjuntion with wind, solar, water and other forms of electricty connected to the same battery (capacitor or anything that will store electricty). We may have a real free energy source.
By Rishi
The problem with alternate energy sources like, wind, waves, or solar is their low level of availability. There is a huge quantity of energy present but not easy to use. A thermal power station, an internal combustion engine, or a hydro-electric station have the energy available at a high temperature or pressure, which makes it easy to design a converter to generate electricity. Also these are easily controlled.

On the other hand waves, wind, the sun and the like keep changing. The equipment to convert these into electricity is cumbersome, large and expensive. Photovoltaics do directly convert sunlight into electricity, but at a low efficiency. Even here the output varies. It produces a DC, which has to be stored in batteries, converted into AC and then fed into the grid.

But, as repeatedly said on varios threads on this site, there are all sorts of energy-sound, spit and other effluents, wind, waves, marine thermal, lightning, and a host of others-lying around untapped. We should explore all ways of recovering usable energy from these. May be Moore's law on computers may be applicable to other branches of engineering and costs will decrease.

By treadair
After submitting a similar idea (see 'Making Money from Noise' in the Docks) this idea was pointed out to me. The only real difference between the two is the level of implementation detail I included. Since this idea made it to the list first I'll just add a few of the possible implementation methods to it so everything will be in one place.

1. The following link describes the auxilliary power units that are
currently being used on 747's (down near the bottom).
Equipment capable of producing electricity similar to the way
dynamic microphones do could be added to these power units to
reduce their energy consumption, saving the airlines money
either by allowing for the usage of smaller/lighter APU's or
reducing the amount of fuel required to run the APU's.

2. The following link describes a study that was done to see how
much money people would be willing to pay to get rid of windmill
farms. It turned out that the closer they lived to them the more
they were willing to pay. The reason for this was the amount of
noise produced by the windmills. I'm including the link just to
verify that the windmills do indeed produce noise as a byproduct
and that being the case, the efficiency of the windmills could be
increased by adding a device capable of converting that noise
into electricity (again based on the way dynamic microphones

3. As far as implementing it in a factory setting goes, personal
experience has shown me that some of them can be quite noisy.
I don't have a link showing how loud the ones I've been in were
but here's a chart of average noise levels from different
sources. It was taken from the link below it. (According to the
chart it looks like elevated trains might make another candidate
for one of these energy-producing devices.)

Aircraft: Near the Plane 140 dbA
Aircraft: Residence Near Airport 80 to 90 dbA
Elevated Train 120 dbA
Industrial Plant 100 dbA
Auto Horn at 25 ft. 100 dbA
Jazz Band 85 to 100 dbA
Loud Stereo 90 dbA
Person Shouting 80 dbA
Noisy Household 75 dbA and up
Truck at 25 ft. 75 dbA
Busy Street at Curb 70 dbA
Dense Traffic at 200 ft. 65 dbA
Office Conversation 60 dbA
Average Conversation 50 dbA
Quiet Household 40 dbA
Quiet Conversation 25 dbA ... anning.asp
By MissPlayful
Listen folks, it’s great to see this and other creative ideas on converting wasted energy into useful energy. But we do need to look at this particular idea in perspective. Consider a noisy truck engine. Much of the energy being produced by that truck motor goes into moving the truck, and some of the remainder escapes as heat in the exhaust fumes. A little bit escapes as noise. So even if you surrounded the truck with devices capable of converting that noise into useful energy you would only capture a tiny amount of the total energy being consumed by the truck engine. And it would cost you a lot of money to do it. My point is this. There is not much energy in sound, even loud sound, and it would be expensive to turn it into useful energy. You simply can’t collect loads of useful energy from a sound source because sound does not carry loads of energy. But you can collect small amounts of useful energy from sound, and I am sure there are situations where that would be valuable.

The basic idea is a good one, but the source - sound - doesn’t carry enough oomph - remember that even very loud sounds are only a tiny vibration in our ear drums. They sound loud to us because we have evolved very sensitive ears - they needed to be so we could hear that lion stalking us! But it doesn’t mean that loud sound carries a lot of energy - it doesn’t.
By treadair

If we added a passive amplifier, or amplifiers, to the mix would that increase the sound levels to a significant amount as far as electrical output is concerned? Not being an engineer, I have no idea if they would.
We can’t extract more energy out of the sound than there is in the sound, and the basic problem is that there is very little energy available in the sound for us to convert to useful energy. We would need to put more energy into the amplifier than we would get back from the louder sound. I am not an engineer either, but I do know that as far as energy is concerned there are no free lunches - you can’t extract more energy out of something than there is in it.

When waves crash onto the shore, a tiny bit of the energy is converted into sound. Most of the energy of the waves is converted into swirling motion of the water and in heating the water and the shore a tiny bit. It’s a great idea to have arrays of large microphones to collect the energy in the sound, but the problem is there isn’t enough energy in the sound to make it worth-while. You need to extract most of the energy from the wave before it breaks.

Great idea conceptually, but not enough energy in sound to make it work in practice, except in specialised instances where small amounts of energy are needed and there is no other tappable source.
By willirovfar
Imagine a fence running along the side of a busy highway. Over 20,000 cars pass by daily, all generating sound. If the fence can somehow be made into a large microphone, a sound collector, would enough sound be collected to generate measurable and collectable electricty? If the fence is over 100 yards long and 3 yards high, that is a large amount of surface area or diaphragm space. Any ideas? Thanks
By DirtpatchSmacky
i can see it now, giant puppy mills, thousands upon thousands of puppies, all caged, hooked up to microphones, and a few cats wandering around outside the cages,, ,,
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By Joe Iley Sanders
I've done some research in this area. My field is seismic oil exploration, specializing in sea floor seismic monitoring. As we work in deeper water, power and wires from the instruments become a bigger and bigger problem.

The current state of art is autonomous continuous recorders with battery power for up to about 60 days of recording. Our work is simply to monitor the voltages sampled and digitized from pressure and motion detectors.

The detectors typically produce about 10 volts per bar meter. motion, (such as a moving coil geophone) is translated to pressure by dividing (volts/meter/second) by 15.

An impulsive seismic source emits about 100 barm at the surface. Ambient noise ranges from about 3 to about 20 micro barm.

I worked this out with resistances in the system and came up with only a miniscule amount of "tappable" power. Not enough to even merit a field test.

My best idea for unconventional energy would be to put small dynamos on all the machines in an exercise parlor.

joe ;-D
By dcosmin
sound is not valuable energy(but 'waste'), and the microphones may cost more than the actual energy obtained over a long,long period of time.
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