Converting noise into electrical energy

[Mahipat Singh]

Could we collect Sound waves in a machine or any sonic instrument ?

If yes, than we can reproduce it in Electric energy !

 

[sophiecentaur]

Could we collect Sound waves in a machine or any sonic instrument ?

If yes, than we can reproduce it in Electric energy !

The answer is, as said earlier, YES - - - BUT.
And that 'but' is so very relevant, because it's all a matter of 'how much energy?' These things are only worth doing if you get back the cost of doing them.

All microphones convert the sound that hits them into electrical energy. If you put a microphone at the focus of a large paraboloid reflector then you will direct more sound energy onto it and, hence, get more electrical energy out of it. However, the principle always applies that you will never get more energy out of a system than is put in.

Having established the principle then you have to consider whether it's a worth while exercise. How much sound power is available? Let's get things in proportion. We sustain permanent hearing damage if we're exposed to sound at a level exceeding 1mW per square metre. To collect just 1W of power from sound at that level, you would need 1000m² of collecting area. (Worth it? - I don't think so) And, in any case, where could you fit a collecting area of that size or what source would actually be that loud at a suitable distance where you could fit a reflector that big?
Normal levels of sound noise around us are around one thousandth of this level so, without deafening ourselves, we would get just 1mW from the same collector. People don't seem to realize just how important the actual NUMBERS are in discussions like this.

There are places where the sound levels are higher than the level for hearing damage. A jet engine (an old fashioned noisy type,I suspect), 30m away, produces 1kW per m² in the 'loudest' direction but how would you gather it? There's no way you could have a 30m/30m collector anywhere on an airport (start of a runway? Joke) and for how long per day would it be collecting this energy? The fact is that modern jet engine design has vastly improved efficiency, due to the fact that the air flows through it differently and it just doesn't produce so much noise. This has reduced sound noise AND all the time the engine is running on less fuel! There is far more benefit from preventing the production of sound noise than you could ever get by (trendy word coming up) 'Harvesting' sound energy.

People are quite happy to believe that Engineers get it right when designing electronic systems, aeroplanes and electrical power distribution. They get it right because they Do the Sums with the available Figures. They don't say "let's build a power station - I've drawn a sketch of what it will look like so let's get started". They do serious calculations involving structure, fuel supply and expect levels of generation eetc.. If just one part of the design is not right then the power station (aeroplane / TV / city / car) will FAIL and cost someone a lot of money (or a life).

The Figures involved in Harvesting sound energy indicate that it is just not worth it. If someone can suggest a situation where it should be considered and there is actually a significant amount of free, 'concentrated' sound energy around then they need to suggest some figures for just how much power would actually be available and what it would cost to 'collect it'. I am not aware of a single 'sound harvesting' scheme anywhere (and there are some very wacky alternative energy schemes about) and I am not at all surprised, because the numbers just don't add up. When the total energy needed to produce a system is greater than the total energy it will produce over its life then you need to ask questions. (Oh boy, did someone say Nuclear?)

 

[Mahipat Singh]

Sound has waves and it needs to collect in the machine or instrument like a room where we can get lot of noise from outside. If this process we can keep than it will become mini electric power station and sound/noises pollution will reduce.

But little bit experiments are happening in world, the exact results are awaiting or taking time !

As i wrote my formula : E=V (electric energy = sound energy), this energy we can transfer one place to other place without wire.

 

[sophiecentaur]

we can get lot of noise from outside.

Absolutely right. The question is HOW MUCH energy?
If someone tells you they have opened a business which earns them money, you would be impressed it it involved £10,000 per week but not so impressed with 10p a week. It's the same with these free energy sources. No one has demonstrated any significant AMOUNT of energy around us because there isn't any more than we can hear. That wouldn't raise a flicker in a small LED.

 

[Mahipat Singh]

Hello, Sir,

thanks to your reply,

I am searching someone who can work on WI-FI electric transmission generated from "Sound Waves" for routine work purpose ?

Like we are getting heat from Sun Rays.

 

[sophiecentaur]

Hello, Sir,

thanks to your reply,

I am searching someone who can work on WI-FI electric transmission generated from "Sound Waves" for routine work purpose ?

Like we are getting heat from Sun Rays.

It is well known that we receive around 1kW from the Sun on every metre square of the Earth's surface. This means that we have a viable source of 'free energy' (pretty much the Only Energy source the Earth ever had).
The sums tell us that solar energy is viable and it is. The sums tell us that there is NOT enough energy in the form you describe. If you have aspirations of ever becoming a 'real' Scientist or Engineer then you must acknowledge that the Actual Values are at least as important as the arm-waving general principles. Adjectives are not enough in arguments like this. You don't run a motor on adjectives - it needs real power.

You seem to be combining two concepts here - Free Energy from background sound and Wireless power transmission. Neither of these is very well established. Perhaps you should look at one at a time.

 

[Mahipat Singh]

Hello, anyone can tell me now what are the frequencies of sound in environment ?

If there are varying sound in diff. frequencies, than we are capable to collect and re-use it by help of machine.

 

[sophiecentaur]

Hello, anyone can tell me now what are the frequencies of sound in environment ?

If there are varying sound in diff. frequencies, than we are capable to collect and re-use it by help of machine.

Have you actually read any of this thread?
How much energy do you need? How much is available? Which number is greater? That is the answer to your question.
I really hope that you don't approach your personal finances in the same way that you are looking at this 'free energy idea'.

 

[gani11vlr]

ya...it is possible...but i think small amount of electricity is produced...but it is applicable for cell phones...used for charging while talking...every particle is disturbed by a force...our sound signals disturb the particles...due to vibration of atoms...electrons are moved...under this condition we can able to produce electricity...

 

[maimonides]

Well, if you know it can be done:
don´t talk, DO IT!
You can buy noise powered electric generators for little money. They are called dynamic microphones. (Or you might use a loudspeaker, works just the same or even better: more area, more energy.) Get one, connect your phone to it and wait for "fully charged".
Or try to power a 1ma LED first and then go bigger/optimize.
Have fun with it.

 

[sophiecentaur]

You really should try to get real about this idea. There is only enough power in your voice to move the microphone transducer. This is followed by am amplifier which needs a POWER SUPPLY. Where's your free energy?
Afaik, the only device ever used which was powered by speech was the old wax cylinder recorder. Shouting at it would produce enough mechanical vibration to record a pattern in the soft wax. You still had to turn the cylinder with added power.
If you are not prepared to include figures in your argument, your opinion has no weight

 

[satheeshg89]

Thanks for helping with my ideas. here i do have some suggestion of using a transducer which can convert any form of energy into electrical energy. though the 2nd law of thermodynamics prevent us by using the sound energy as an electrical energy here comes a device sonea. dn y dnt we try for another device which would be a combination of both sonea and transducer.
please do mail me @ satheeshg89@gmail.com. i think if we all work hard with a cordination our project will be a successfull one.

i suggest every member who work for it to share their details for a combined work

 

[sophiecentaur]

You still don't seem to be getting the basic flaw in what you are saying. There are many transducers that produce electrical energy from sound. The fact is that there is NOT ENOUGH ENERGY available to make it worth while. Stand and listen. Does the sound around you knock you off your feet or even make leaves tremble? If there isn't sufficient energy for this then there isn't enough to produce a useful amount of electrical Power.
You are not suggesting anything New. You are just revisiting something that has already been considered and discarded with good reason.

 

[sophiecentaur]

Thanks for helping with my ideas. here i do have some suggestion of using a transducer which can convert any form of energy into electrical energy. though the 2nd law of thermodynamics prevent us by using the sound energy as an electrical energy here comes a device sonea. dn y dnt we try for another device which would be a combination of both sonea and transducer.
please do mail me @ satheeshg89@gmail.com. i think if we all work hard with a cordination our project will be a successfull one.

i suggest every member who work for it to share their details for a combined work

With respect, why can you not have the courtesy to use proper spelling? There is no limit to the number of characters allowed on this site and much of what you write is unintelligible. You are not just talking amongst your friends on this forum. If you look at what other people write, you will see that they, mostly go to some trouble to write properly and in full.

What are you actually talking about?

 

[Khashishi]

Sorry, there's prior art on this one. I saw some people working on something like this in some energy conference at MIT Museum of Science. They were hoping to power some small lights in a tunnel off of traffic noise, I think.

 

[sophiecentaur]

Did they get any joy?
In very confined spaces there might be some energy available but I'd bet the noise level would have precluded any humans being comfortable in there. I reckon they'd have more joy from a wind turbine, using the draft from the passing vehicles.

In those extreme conditions there could possibly be some usable energy but I thing the OP was hopeful that the sound level in one's living room could, somehow, charge a mobile phone. The energy return (harvest) would normally be of much less value than the saving of energy by using more efficient machinery in the first place.

 

[Bobbywhy]

The use of piezoelectric materials to harvest power has already become popular. Piezoelectric materials have the ability to transform mechanical strain energy into electrical charge. Piezo elements are being embedded in walkways to recover the "people energy" of footsteps. They can also be embedded in shoes to recover "walking energy".

http://en.wikipedia.org/wiki/Energy_harvesting

Notice the above systems use mechanical strain energy to generate electrical power in small amounts. NO WAY acoustic waves could be used for appreciable power...listen to sophiecentaur and do the math.

 

[sophiecentaur]

I could imagine an energy harvesting system based on a Methane fuel cell which could make use of the 'human products of digestion'. Particulaly useful in lifts and submarines where it could help with the 'ambience'.

 

[satheeshg89]

with respect to your reply based on usage of methane fuel cell , on direct oxidation of hydrocarbons which result in methane fuel cell there is a problem of inhibit methane cracking. so to avoid this can you suggest some ideas.

 

[sophiecentaur]

OH well. (I'm not a Chemist) That idea is at least as viable as using the sound levels in your front room as an energy source.

 

[Alinoonva]

Hi all,

I have been interested in the conversion of sound into electrical energy as well. I have been reading everyones post about this and how it is seemingly impossible or yet not efficient to convert sound energy into electricity. I am not a physicist but I do study biology and the human ear basically converts sound into electrical signals which are then interpreted by the brain. What I am interested in is understanding how to measure whether this is an energy consuming process (some sort of amplification which I don't think it is) or not. If it is not energy consuming that the largest problem is physically bringing dissipated sound from a large area into a small condensed area where it can create mechanical motion.

The ear takes sound from a large space (via the outer ear) and then propagates that sound through the auditory canal into a smaller more condensed space and causes vibration to the tympanic membrane which causes vibration of the malleus incus and stapes connected to the fluid filled cochlea. Inside the cochlea there are hair like cells... the vibration of the fluid moves these hair like cells (mechanical energy) and that movement is converted into nerve impulse and sent to the brain via the cochlear nerve.

I know this is possible I would really appreciate some help as how to create measurement protocols so I can assess this.

 

[sophiecentaur]

There is an essential difference between detection of signals and using them as a source of energy. The ear, along with all other detection systems (ignore the crystal set), has the job of detecting very low levels of sound signal energy and uses energy from the body to transform this signal into a form that can be used by the brain. The body has to expend energy (from food) to achieve this.

If you want to 'harvest' energy, you can't use amplifiers but you need enough energy for the harvesting system to drive itself and have a worthwhile amount left over. (Otherwise the system is a waste of time and energy). In nearly all circumstances, the flux of sound energy is too low to make harvesting worth while - it would involve deadly levels of sound. If you are talking 'total cost', it is far better to make machinery more efficient so it produces less (wasted) noise energy in the first place. That is a much better engineering solution in most cases.

I guess there may be viable applications for powering very low power devices from available sound energy, because this makes them 'wireless' and they don't need a feed of power from elsewhere. (A bit like the popular solar / wind driven remote systems we are starting to see all over the place.) But the sound levels required are extremely high if you want even just a few miliWatts of usable power. In some cases, you'd find that the total energy put into building the installation could be more than the total energy it can ever supply. It's a possible answer to localised power requirements but we will never 'save the planet' with such sound energy harvesting. (No point in putting one in front of your TV, for instance)

 

[Alinoonva]

Thanks for the reply. Are you sure that the body's conversion of sound to electric signal is done using energy?

What is the crystal set?

Your reasoning for not harvesting sound: I understand sound in large space is useless but what if sound was culminated from a large area and then transferred into a very small dense area? For example if we accumulate sound from cars made within a tunnel and guided it to a very small area (almost like a funnel) would we be able to create mechanical energy at the smaller end of that funnel? Or do you still think it is far too small of a number?

 

[sophiecentaur]

Thanks for the reply. Are you sure that the body's conversion of sound to electric signal is done using energy?

What is the crystal set?

Your reasoning for not harvesting sound: I understand sound in large space is useless but what if sound was culminated from a large area and then transferred into a very small dense area? For example if we accumulate sound from cars made within a tunnel and guided it to a very small area (almost like a funnel) would we be able to create mechanical energy at the smaller end of that funnel? Or do you still think it is far too small of a number?

Oh boy. You must be soooo young! It was the first type of Radio receiver that enthusiasts used. It consisted of a tuned circuit and a rectifier diode (crystal) with no amplification, that fed a sensitive pair of headphones.

Can you imagine the cost of a suitable funnel, fitted into the side of a tunnel? It would need to have a vast opening and have a long enough taper to match the sound into a suitable transducer. To justify it, you would need actual figures for the likely energy return. How much sound energy flux do you think there is in a tunnel full of cars? You wouldn't get more than that out even if the system were 100% efficient. This is a hard nosed engineering problem which can't be assessed by just arm-waving.

 

[ramganesh]

As sound energy is not sufficient for producing large amount of electrical energy
ie.,80db=1milla watt so why don't we go for energy amplifiers having 10^6 gain

 

[nasu]

As sound energy is not sufficient for producing large amount of electrical energy
ie.,80db=1milla watt so why don't we go for energy amplifiers having 10^6 gain

One reason may be that energy amplifiers do not exist so far.

 

[sophiecentaur]

As sound energy is not sufficient for producing large amount of electrical energy
ie.,80db=1milla watt so why don't we go for energy amplifiers having 10^6 gain

An "amplifier" requires a power supply. That power supply would need to provide the extra 99999extra mW. Where would that come from? Answer: the mains electricity supply and not the traffic noise.

When people try to come up with solutions to Engineering problems, they really should apply some of the discipline that Engineering demands. Rule number one: you don't get 'owt for nowt.

 

[Dek]

Surely we're looking at this from the wrong perspective. When sound is produced this is energy from it's dissipation. We should be thinking about harnessing energy at the point of sound being created. The best place to do this is in looking at waves, and picking up the energy before it dissipates against the rocks and sand.

 

[sophiecentaur]

The best approach is to reduce the amount of noise produced in the first place. It's about making more efficient systems.

 

[Mahipat Singh]

Researching on clouds methodology, where i am getting lot of sounds and electricity, this will help me to produce huge amount of sound into electricity.

 

[sophiecentaur]

What constitutes a "huge amount"? 1W, 1MW? If you can't answer that then you have no answer to any of this.

 

[nydhruv]

I read that sound absorbing material absorb the sound waves and store it in the form of energy, usually heat. Will it be possible to store this energy through some mechanism over a period of time and then use when there is a requirement?

 

[sophiecentaur]

Why do people ignore the QUANTITIES involved? Is this not the whole crux of this topic? Does the amount of energy involved not strike you as relevant?

 

[Bobbywhy]

nydhruv, Welcome to Physics Forums!

Your suggestion to store heat from the absorption of acoustical energy makes no sense. Did you read sophiecentaur's post(s) above? Do your maths. The AMOUNT or QUANTITY of this heat, if you calculate it, will be tiny, miniscule, infinitesmal, and hardly measurable.

 

[LastTimelord]

Noise is not a very large amount of energy at all. If a person were to scream as loud as they could for 5 years, they will have produced enough energy in noise to heat a cup of coffee.