Turning Heat Into Sound Into Electricity

WrongSizeGlass writes "Science Daily is reporting on work by physicists at the University of Utah who have developed small devices that turn heat into sound and then into electricity. 'We are converting waste heat to electricity in an efficient, simple way by using sound [...] It is a new source of renewable energy from waste heat.' They report that technology holds promise for changing waste heat into electricity, harnessing solar energy and cooling computers and radars."

Comments

Linux Toaster?

[Maliron]

This new technology should bring us one step closer to the uber efficient linux toaster! "Anyone want more bread? I need more power to finish this compile!"

Re:Linux Toaster?

[Petaris]

I know this is a bit off topic but given your post I just can't help but to respond with this: Toaster oven linux appliance :)

- Petaris

"The World is Open. Are You?"

Re:Linux Toaster?

[Maliron]

Not sure why my comment was considered off topic, the article even suggests PC use.. Toasters generate exuberant amounts of heat, an ideal source of electricity (using this new method) to power the toaster PC. hehe Anyways, cool link! This story reminded me of the BSD toaster that was /.'d a while back, which triggered my comment.

Does it rock!?

[Todd Fisher]

I need a renewable energy source that I can rock out to all day long, all night strong!!

"convert heat into electricity has to key steps"

[Anonymous Coward]

Gee. I wonder what they are.

But....

[a.phoenicis]

But does it change waste heat into electricity? I'm not quite sure based on that write-up...

Re:But....

[CogDissident]

Waste heat is the exact same as normal heat. It just means that you dont "want" the heat.

Re:But....

[p3d0]

You need to adjust your sarcasm threshold.

Re:But....

[Anonymous Coward]

So in other words, it isn't the fucking same, is it?

Re:But....

[lisaparratt]

No, it turns it into Techno. Small generators mounted on ravers create the actual electricity.

Re:But....

[grimdestripador]

Low differential temperatures between two heat resevoirs results in extremely low output efficiencies

Re:But....

[Original Replica]

So Someone could make the radiator on a hybrid out of this and get even more efficiencey out of a gallon of gas. Suddenly thwe waste becomes wanted heat.

Re:First post!!

[Anonymous Coward]

Took it away from the shock site troll...

Sound to electricity.

[snowraver1]

Now they need to refine this to 100% effiecency and attach one to my wife.

Re:Sound to electricity.

[Wicko]

Save electricity! Piss off your wife! Attach to your kids!

Re:Sound to electricity.

[Simply Curious]

On the other hand, any inefficiency would show up as heat, allowing it to cycle through towards absolute zero.

Wait a minute...

Ack! Stupid Second Law of Thermodynamics.

Re:Sound to electricity.

[Anonymous Coward]

Funny, over on myhusbandisageek.com she said the exact same thing about you. The highest rated comment was how you'd take it apart and electrocute yourself.

Sound, you say...

[NeoTerra]

Why bother turning the sound to electricity? Then I could just load up some music to the car, and play the sound as the engine warms up :) I suppose that's why it's not getting put into cars :)

Re:Sound, you say...

[Idbar]

As far as you don't play any copyrighted material. But I bet those sounds will soon be copyrighted.

Re:Sound, you say...

[NeoTerra]

I suppose it's a matter of time before we get DRM enabled cars.

Re:Sound, you say...

[HalifaxRage]

Finally, a use for the windows startup sounds!

Re:Sound, you say...

[Phisbut]

I suppose it's a matter of time before we get DRM enabled cars.

Don't we already have those? Most cars that I see parked on the street require some sort of secret key in order to operate properly, and it seems to be a crime to try and start the engine by circumventing the need for a key...

Re:Sound, you say...

[Lockejaw]

And you can't just go to the hardware store and make a copy of your own legitimate key.

Efficiency as opposed to thermoelectric?

[Anonymous Coward]

I just skimmed the article, but I didn't see mention of the efficiency of this process. What are the advantages to converting the heat to sound first, rather than directly to electricity via thermoelectric processes?

Re:Efficiency as opposed to thermoelectric?

[hwyengr]

Is the efficiency really that important? The heat they're using was 100% wasted in the first place.

Re:Efficiency as opposed to thermoelectric?

[oskay]

On the other hand, thermoelectric devices with significant capacity are pretty expensive. This might be a much less expensive route to the same goal.

(On the third hand, this is military funded research, so I'd be a little bit surprised if that were the make-or-break feature.)

Re:Efficiency as opposed to thermoelectric?

[cosinezero]

And from the looks of that giant glass pipe lit by a blowtorch, my money's on the researchers being 100% Wasted while thinking this one up, too.

Re:Efficiency as opposed to thermoelectric?

[LWATCDR]

I think cost is more important the efficiency. If it was cheap enough and if you could say get 10% out of it it could be very useful.
Imagine replacing a car radiator with it?

Re:Efficiency as opposed to thermoelectric?

[dch24]

You want to read the Original Article. Although the link above is almost an exact copy, there's some interesting stuff at the bottom of the original:

Physicist Orest Symko's graduate students will present their studies during an Acoustical Society of America technical session from 8 a.m. to 10:05 a.m. MDT Friday, June 8 in Parlor B of the Hilton Salt Lake City Center hotel, 255 S. West Temple.

It would be interesting to hear all the questions there. I imagine yours will be handled pretty well.

Obviously the conversion to sound can't beat Carnot's Theorem, and it says in the article it doesn't start until there's a temperature gradient of at least 90 degrees F. In other words, it's not very efficient.

Re:Efficiency as opposed to thermoelectric?

[weszz]

Once the second student stepped in, then it got better... the air pressure is the key... until you puncture it and it blows up...

She built cylindrical devices 1.5 inches long and a half-inch wide, and worked to improve how much heat was converted to sound rather than escaping. As little as a 90-degree Fahrenheit temperature difference between hot and cold heat exchangers produced sound. Some devices produced sound at 135 decibels -- as loud as a jackhammer.

-- Student Nick Webb showed that by pressurizing the air in a similar-sized resonator, it was able to produce more sound, and thus more electricity.

He also showed that by increasing air pressure, a smaller temperature difference between heat exchangers is needed for heat to begin converting into sound. That makes it practical to use the acoustic devices to cool laptop computers and other electronics that emit relatively small amounts of waste heat, Symko says.

Re:Efficiency as opposed to thermoelectric?

[ScentCone]

but I didn't see mention of the efficiency of this process

Never mind the hair splitting over "efficiency." How about the absurdity of using the word "renewable?" Where is the heat coming from? Is THAT source of energy renewable (meaning, something that grows back or becomes re-available after it's been used, with less energy required to make it that way than you get out of it? It's maddening to see presumably technical discussions about something as important as energy and its practical applications... and the main modifying word put in front of the work "energy" is... wrong. Solar energy isn't renewable... it's continually available from the sun. Logs for your fireplace could reasonably be said to be renewable, if you take the trouble (and other energy) and have the time to renew them and re-harvest them. Wind isn't renewable - it's just generally, mostly available... and it requires an ongoing expense and complex infrastructure to turn it into something handy like electricity.

Oil (from the ground, anyway) will get used up (if we're talking in reasonable time windows, here) eventually. So, let's call that NOT renewable. An electricity-producing technology (as in TFA) that happens to produce some using waste heat from burning hydrocarbons like coil or oil is NOT "renewable". Honestly: people seem to think that "renewable" and "efficient" or "not wasteful" mean the same things. They do NOT. Why does this semantic fuss matter? Because we're going to raise an entire generation of science-less, witless consumers that bandy about terms like "green" and "renewable" and "hydrogen economy" without actually having the critical thinking skills to see how it all does (or does not) fit together. Taking the meaning away from words dumbs all communication down, and erodes our culture's ability to do intellectually challenging things.

Re:Efficiency as opposed to thermoelectric?

[mikiN]

So first we had laptop batteries catching fire, soon we'll have laptop coolers that go out with a bang?

Re:Efficiency as opposed to thermoelectric?

[Elfich47]

From the process they are describing it could be fairly cheap and easy to construct once the mechanics are figured out. Large power plants would be more then happy to adjust their exhaust stacks to add something that got them an additional 5% power generation with no more moving parts.

Re:Efficiency as opposed to thermoelectric?

[Midnight Thunder]

[i]And from the looks of that giant glass pipe lit by a blowtorch, my money's on the researchers being 100% Wasted while thinking this one up, too.[/i]

This approach has worked for music, why not for science ;)

Re:Efficiency as opposed to thermoelectric?

[Chandon Seldon]

Music that is nonsensical is considered "Brilliantly Artistic". Science that is nonsensical isn't - mostly it's useless.

Re:Efficiency as opposed to thermoelectric?

[Dan Ost]

Carnot's Theorem applies to heat engines that use a gas to do work.

It's not clear to me that Carnot's Theorem applies to this technique.

Anybody want to chime in with some insightful comment on this?

Re:Efficiency as opposed to thermoelectric?

[Altus]

I caught that too, but really it would not be advised to explain where this "free" electricity comes from to someone writing an article like that.

That said, everyone is focused on using these for waste heat conversion which is great and may improve the efficency of many of our electrical and mechanical systems (including power generation systems), but the other use for this would be harnessing solar power which could be pretty cool if it significantly beats the efficiency of photo voltaic cells.

Re:Efficiency as opposed to thermoelectric?

[Phisbut]

Never mind the hair splitting over "efficiency." How about the absurdity of using the word "renewable?"

Wow, you woke up in a pedantic mood this morning...

Solar energy isn't renewable... it's continually available from the sun. [...] Wind isn't renewable - it's just generally, mostly available...

We call "renewable" energy a form of energy that we're not exhausting by using up. Harvesting solar energy today won't make less sun energy available tomorrow. The sun will not expire faster if we use its energy to produce electricity. Hydro is the same. Water will flow from the top of the mountain to the bottom whether we build a dam or not, so while we are harvesting the water's potential energy, we are not the cause of its exhaustion (gravity is, damn you gravity!).

When you do something "from scratch", do you start by creating a whole universe from a Big Bang instead of using what's already there (thus, not starting really from scratch)? People do stuff from scratch without creating universes, and the sun provides renewable energy.

Taking the meaning away from words dumbs all communication down, and erodes our culture's ability to do intellectually challenging things.

Words have accepted meanings, and that is how we communicate. Agreed upon meanings are usually recorded in big books we call dictionaries. You should get one, they're really good.

May I recommend The American Heritage® Dictionary of the English Language, Fourth Edition, which defines renewable as :

Relating to or being a commodity or resource, such as solar energy or firewood, that is inexhaustible or replaceable by new growth.

Or maybe you would prefer WordNet® 3.0© 2006 Princeton University

capable of being renewed; replaceable; "renewable energy such as solar energy is theoretically inexhaustible"

Here's a last one from The American Heritage® Science Dictionary

Relating to a natural resource, such as solar energy, water, or wood, that is never used up or that can be replaced by new growth. Resources that are dependent on regrowth can sometimes be depleted beyond the point of renewability, as when the deforestation of land leads to desertification or when a commercially valuable species is harvested to extinction. Pollution can also make a renewable resource such as water unusable in a particular location.

Re:Efficiency as opposed to thermoelectric?

[imsabbel]

What do you thing that sound is?

Just another way to adiabatically compress a working gas...

Re:Efficiency as opposed to thermoelectric?

[zippthorne]

But.. what does their device do to the upstream temperature (or the efficiency of any upstream machinery)? Waste heat is called "Waste" for a reason...

Re:Efficiency as opposed to thermoelectric?

[ScentCone]

I would argue that the definitions you've cited are just examples of the cognitive battle already having been lost on this one. It doesn't make the word any more precise or actually meaningful.

Why not call gravity-powered electricity generation (say, the Hoover Dam) just that: gravity-powered. That means something, especially if you mention the hydro part of it in conjunction. As opposed to "tidal power" (also hydro, but a different beast).

It's not pedantic, though, to mention that there is NOTHING "renewable" about creating electricity from waste heat that, itself, is created while burning oil or coal. It's just a a more efficient energy extraction than was otherwise being performed. But there is NOTHING "renewable" about it when used in that way. Using that word (in that context) is almost as wrong as referring to hydrogen as a "new source of energy," as so many wannabe energy experts call it when getting fake-man-on-the-street interviewed by BP for a commercial. Simply choosing a more precise word isn't any HARDER than using the wrong one, but it allows an audience's vocabulary and longer-term understanding of the subject matter to actually grow. And that translates into things like how they vote, what they buy (or don't), and so on. Dumbing this down so that things that are simply more efficient than they have been are suddenly "renewable," even as they consume a finite supply of some fuel ... that's not just dumbing it down, it's a major misrepresentation.

Re:Efficiency as opposed to thermoelectric?

[Anonymous Coward]

Working in an unrelated project, at the University of Utah--- I heard about this a couple years ago. I seem to recall hearing a figure of something ~80% efficiency in the process of heat to sound to electricity. A device to convert directly from solar energy has not yet been created to my knowledge.

Re:Efficiency as opposed to thermoelectric?

[marcosdumay]

Carnot's theorem applies to any thermal machine. The actual implementation doesn't matter.

If not, one would break 2nd law by putting a thermal machine feeding a thermal pump.

Re:Efficiency as opposed to thermoelectric?

[wsherman]

Carnot's Theorem applies to heat engines that use a gas to do work.

The "proof" of Carnot's Theorem actually has two parts. First, for the case of heat engines based on compressing ideal gasses, one calculates how much heat has to flow between two different reservoirs in order to do a certain amount of useful work (i.e. the "efficiency"). Second, one shows that if any other heat engine ever had a different "efficiency" then one would be able to construct a perpetual motion device of the second kind.

The argument is basically that, since no one has ever observed either a natural or constructed perpetual motion device, the maximum efficiency of any heat engine must be the same as a heat engine based on ideal gases.

A rigorous proof of the Second Law is difficult because you would have to show that no possible physical system can ever exceed the Carnot efficiency. At this point, there are still a lot of physical systems that can not be modeled exactly.

On the other hand, the "Fluctuation Theorem" goes a long way toward showing that the standard thermodynamic models (e.g. classical and quantum statistical mechanics) obey the Second Law of Thermodynamics. As I understand it, the Fluctuation Theorem is based on something like time reversal symmetry - that is, classical and quantum statistical mechanics both have something like time reversal symmetry which is the basis for the proof of the Fluctuation Theorem.

Re:Efficiency as opposed to thermoelectric?

[Dan Ost]

Carnot's theorem applies to any thermal machine. The actual implementation doesn't matter.

Is that true? I thought it only applied to engines that used gas expansion/contraction to extract work from a heat gradient. Are, for instance, thermopiles limited by Carnot's theorem?

If not, one would break 2nd law by putting a thermal machine feeding a thermal pump.

This is demonstrably false. Beating Carnot's theorem does not imply 100 percent (or greater) efficiency. The 2nd law would still be preserved.

Re:Efficiency as opposed to thermoelectric?

[It'sYerMam]

Why not call gravity-powered electricity generation (say, the Hoover Dam) just that: gravity-powered. That means something, especially if you mention the hydro part of it in conjunction. As opposed to "tidal power" (also hydro, but a different beast).

Refer to Wittgenstein; meaning is use, and renewable is used to mean the definition that has been explained to you. I can imagine the scene at Bletchley park, now:

"But these encrypted messages are just a bunch of characters! They don't mean anything!"

Meaning is determined not by what one person thinks - not even by what the dictionary says - it is determined by how it is used in a particular context.

Re:Efficiency as opposed to thermoelectric?

[ScentCone]

Meaning is determined not by what one person thinks - not even by what the dictionary says - it is determined by how it is used in a particular context.

Right! So, consider my post and this thread to be an attempt to encourage people to use that word (and the others that are thus required) in a more meaningful way. If a single word is used to represent lots of substantially different things (in this case, "renewable" interchangeably meaning the same thing when referring to a marginally better way to burn coal and also using solar energy). I'm not complaining about the evolution of language. I'm complaining about the DE-evolution of language. The loss of precision. The inability to know, from the use word used, what is actually meant... or worse, to be MISLED by the choice of a particular word. That's fine for advertising, but not for science.

Re:Efficiency as opposed to thermoelectric?

[Jorgandar]

This could make refrigerators very effecient. Collect waste 'heat' from the refrigerators heat sinks and pump the power back into the machine to power it...or something like that. :)

Re:Efficiency as opposed to thermoelectric?

[JasonKChapman]

I would argue that the definitions you've cited are just examples of the cognitive battle already having been lost on this one. It doesn't make the word any more precise or actually meaningful.

I understand what you're saying, but if you want to play the "strict definition" game, you have to play it all the way. How can you possibly refer to "the cognitive battle" while demanding such restrictions on the use of language? Where are the weapons? Where is the blood? There are none, of course. Somehow, everyone knew you were using the word "battle" figuratively rather than literally, because its original definition of "armed conflict" has broadened considerably over time.

Why not call gravity-powered electricity generation (say, the Hoover Dam) just that: gravity-powered. That means something, especially if you mention the hydro part of it in conjunction. As opposed to "tidal power" (also hydro, but a different beast).

But tidal power is powered by gravity. That's what causes tides, after all. Look, it doesn't matter what existing word or category you choose, there will always be a way to argue that it's wrong. Let's call it gloobish energy, instead. As long as most of the reference sources agree on what gloobish means, then we have a symbol we can use to relate a large concept in a very efficient package. That's what language is for. When your computer boots up, do you look for little leather straps on its knee-length shoes?

Right now, the marketplace of ideas has settled on a meaning for the symbol renewable energy. Fine. Me? I vote for "gloobish."

Re:Efficiency as opposed to thermoelectric?

[Anonymous Coward]

So is all your hot-air renewable, or non-renewable? I got confused....

Re:Efficiency as opposed to thermoelectric?

[ThreeSpace]

I think you're confusing the second law of thermodynamics with the law of conservation of matter-energy. If you hooked up a thermal machine to a heat pump, you'd decrease entropy without an input of energy into the system, violating the second law of thermodynamics.

Re:Efficiency as opposed to thermoelectric?

[Chris Burke]

I would argue that the definitions you've cited are just examples of the cognitive battle already having been lost on this one. It doesn't make the word any more precise or actually meaningful.

The definition of "renewable" given by the dictionaries is quite meaningful and useful. It makes a clear and significant distinction between itself and non-renewable energy sources. It's just not sufficiently precise for you. Well it's not meant to be, it's meant to cover a wide range of natural resources that are by their nature refillable or inexhaustable. You can use more precise words for specific technologies if you want to, but more specific terms also do not serve the same purpose as "renewable" in language so it still serves a purpose. Besides if your goal is pedantry why stop with mere imprecise words to describe a broad class of significantly different facilities when you should be using full blueprints to represent what exact tech you are talking about. Otherwise I can't understand what exactly you mean by "gravity-powered".

I agree with your criticism of saying "renewable" with regard to waste heat from fossil fuel electricity generation. It could be argued that being the universal waste product heat itself is a "renewable resource" but that's a stretch since the whole point is attaching the device to an existing waste-heat-from-electricity-generating device.

Re:Efficiency as opposed to thermoelectric?

[maxume]

Can a thermopile extract more energy than is flowing through it?

No. The energy flowing through it is determined by the temperature on either side of it, thus, it is a heat engine.

Re:Efficiency as opposed to thermoelectric?

[ScentCone]

but if you want to play the "strict definition" game

It's not that I want a series of strictly defined words that are locked in time and meaning. I don't care if we have this discussion in French, and start an entirely new, gloobishly wonderful set of words for use when talking about energy extraction, transformation, delivery, and use. What I DO care about, is when a large, complex body of issues is glibly reduced to a single word. It's lossy compression. It ceases to be useful because even given the context of a conversation, you can't necessarily divine from that word information that it no longer can convey. When "renewable" no longer actually means "able to be renewed," then... what word WOULD you use for that purpose? And when "renewable" DOES get used to mean "abundantly available" (as in solar, wind, or hydro - none of which require renewing!), what word WOULD you use to mean that in other contexts? Mom made a really big pot of pasta tonight, more than we can eat, so... the spaghetti dinner is renewable?

I don't care WHAT words are used. But when you have two very different concepts to convey, using one word to represent them both means that it ceases to represent EITHER of them, unless you're willing to settle for less or (much worse!) wrong information conveyed by that word.

Language will and should change. But clarity in discussing complex or nuanced things is essential, or the complexity and nuances cease to be communicated. Even simple complexity - like the difference between a distillable crop plant that you have to work to grow back and the tide, which is going to keep sloshing in and out of your city's harbor whether you use it or not. When (back to TFA), we talk about "renewable" energy when we may really mean "another way to get electricty from NON-renewable sources of heat" - how has your marketplace of ideas' use of that word actually conveyed useful information? It hasn't, and it can't, if it uses the same word to describe solar energy as it does better burning of coal.

And the editors of a tech/science site aimed at a brighter-than-usual audience shouldn't reflexively use, or support the use of words that erode meaning. It would be like using the phrase "*nix", permanently, instead of saying Linux or Unix. Sure - the marketplace of ideas will probably get what you mean in SOME contexts - but they are NOT the same thing in almost every context that they're talked about here.

Re:Efficiency as opposed to thermoelectric?

[wsherman]

This is demonstrably false. Beating Carnot's theorem does not imply 100 percent (or greater) efficiency. The 2nd law would still be preserved.

Let's say you have a heat reservoir (e.g. a coal fire) and a cold reservoir (e.g. a cooling tower). You could just let the heat from the hot reservoir flow to the cold reservoir with nothing else happening. You could also set up a steam engine so that the flow of heat from the hot reservoir to the cold reservoir caused some of the heat to be "converted" to mechanical energy (or electrical energy or something equivalent). Now, ideally you would want as little heat as possible to flow between the reservoirs with as much heat as possible being converted to mechanical energy. Carnot's Theorem places an upper limit on how "efficient" this process can be. Basically, the smaller the difference in temperature between the two reservoirs the more heat will flow between the reservoirs and the less heat will be converted to mechanical energy.

Let's now consider a different scenario. Suppose you have some mechnical energy (e.g. some electricity) and you want to create a temperature difference between two heat reservoirs (e.g. you want to air condition your apartment). In this case, you want to do as little work as possible (keep the electric bill low) while moving as much heat from the cooler reservoir up to the hotter reservoir (moving the heat out of your apartment). Basically, you want to minimize the "conversion" of mechanical work to heat while maximizing the flow of heat between the reservoirs. Carnot's Theorem also applies here. You have to do less work to move heat between reservoirs that are at almost the same temperature and you have to do more work to move heat between reservoirs that are at very different temperatures.

For the second part of Carnot's Theorem, imagine that you found one (reversible) process where there was a lot of heat flow between the reservoirs for a given amount heat-work conversion and another (reversible) process where there was very little heat flow for a given amount of heat-work conversion - assuming the same temperature difference between heat reservoirs for both processes. You could hook these two processes together and have a perpetual motion machine of the second kind.

To put it another way, if you could find either an air conditioner or a power plant that was not limited by the Carnot Theorem then you could use your air conditioner to generate the temperature difference to run your power plant and you could use the electricity from your power plant to run your air conditioner all while having electricity left over to power your television (i.e. you'd get free energy from your power plant - no more having to burn coal).

Re:Efficiency as opposed to thermoelectric?

[StikyPad]

Wow. Insightful, comprehensible, logical, AND true, all in one post. WTF is Slashdot coming to?

Re:Efficiency as opposed to thermoelectric?

[nasch]

When "renewable" no longer actually means "able to be renewed," then... what word WOULD you use for that purpose? And when "renewable" DOES get used to mean "abundantly available" (as in solar, wind, or hydro - none of which require renewing!), what word WOULD you use to mean that in other contexts? Mom made a really big pot of pasta tonight, more than we can eat, so... the spaghetti dinner is renewable? You're missing the meaning. "Renewable" isn't being used to mean there's a lot of it. It's being used to mean there is practically an actually or potentially limitless supply of it for the future. Trees, for example. Use one tree, plant a tree, you've renewed the resource. Solar: convert some solar energy to electricity, and there is automatically more solar energy arriving the next day. The point is not that there are a lot of trees, or that there is a lot of sunlight. The point is the ongoing supply of them - the resource is (or can be) continually *renewed*. If your mom's pot continually produced more spaghetti without having to go to the store (such as the sun produces light), then yeah it's a renewable dinner. Oil - not renewable, because there's a finite supply of it. If oil were being spontaneously produced in the earth, then it would be a renewable resource, regardless of whether there were a lot or a little.

Whether plants and sunlight should be referred to with the same word, since one requires work from us and the other does not, is another question. And the technology being discussed here is clearly not renewable energy.

Re:Efficiency as opposed to thermoelectric?

[Anonymous Coward]

[retard]l00k @ me i'm a moran[/retard]

Re:Efficiency as opposed to thermoelectric?

[z-j-y]

what are you talking about? can you be more specific? you cannot achieve better efficiency than a Carnot engine as long as 2nd law of thermodynamics is not violated. clever designs like Maxwell's demon must be treated with greatest suspicion first.

Re:Efficiency as opposed to thermoelectric?

[Kagura]

So you finally figured out the secret to perpetual motion, eh?

Re:Efficiency as opposed to thermoelectric?

[Dan Ost]

To put it another way, if you could find either an air conditioner or a power plant that was not limited by the Carnot Theorem then you could use your air conditioner to generate the temperature difference to run your power plant and you could use the electricity from your power plant to run your air conditioner all while having electricity left over to power your television (i.e. you'd get free energy from your power plant - no more having to burn coal).

I'm still not buying this.

Let's say that for a given heat gradient, the Carnot efficiency is 3%. Are you saying that if I had some magical process that was 4% efficient for the same heat gradient that I could build a perpetual motion machine? That can't be right. Even if my magical process was 99% efficient, as long as it's less than 100% efficient, I still haven't violated the 2nd law (although I have beaten Carnot).

I have a suspicion that neither of us is actually making the argument that the other thinks he is. Certainly, your post is entirely too rational and well written for you to be making the argument that it seems to me that you're making.

Re:Efficiency as opposed to thermoelectric?

[Calinous]

No moving parts, that's the advantage.
      Except the thermocouple, every device (that I know of) that convert heat to electricity has moving parts.

Re:Efficiency as opposed to thermoelectric?

[shenanigans]

Yes, the efficiency is important. If already existing technology can do it better then why bother?

Re:Efficiency as opposed to thermoelectric?

[Urkki]

Let's say that for a given heat gradient, the Carnot efficiency is 3%. Are you saying that if I had some magical process that was 4% efficient for the same heat gradient that I could build a perpetual motion machine? As far as I understand (I'm sure I'll be corrected if I'm wrong), if theoretical maximum efficiency to one direction is 3%, then to the other direction it would be 97%. Now if you do the first direction at 4%, and can still manage the other direction at (close to) that 97% efficiency, you'd get more than 100%.

Re:Efficiency as opposed to thermoelectric?

[Dan Ost]

Since the two processes are in series, their efficiencies would multiply, not add. So, if we have a process that is 4% efficient drawing heat from the reservoir and a second process that is 97% efficient at placing heat into the reservoir, the system as a whole is only 3.88% efficient (.04 * .97). If both processes were 99% efficient, the system as a whole would be 98% efficient (.99 * .99).

To violate the 2nd law and build a perpetual motion machine of the 2nd kind, the system efficiency has to be at least 100% which means that either both processes must be exactly 100% efficient or that at least one of the processes has to have an efficiency greater than 100%.

Re:Efficiency as opposed to thermoelectric?

[Urkki]

Since the two processes are in series, their efficiencies would multiply, not add. As far as I can see, they are not in series, but in a star formation. Hot heat reservoirs, cold reservoir, and one energy storage, all connected with heat pump.

First the pump lets 100 units of energy to flow from hot to cold reservoir, extracting and storing 2.99 units of energy, while actually transferring 96.9 units to cold reservoir.

Then it reverses, using 2.98 units of stored energy left to force that 96.9 units back from cold to hot reservoir.

Now, if you change that 2.99 units to 3.99 units, without chaning the other numbers accordingly, you end up with almost 1 unit of free energy. No can do.

Re:Efficiency as opposed to thermoelectric?

[Timberwolf0122]

(i.e. you'd get free energy from your power plant - no more having to burn coal

Get over hee young man! In this house we obay the laws of THERMODYNAMICS!

Re:Efficiency as opposed to thermoelectric?

[Anonymous Coward]

Imagine replacing a car radiator with it?

No.

Re:Efficiency as opposed to thermoelectric?

[Nutria]

Imagine replacing a car radiator with it?

Yes, but what would you do with it?

Seriously. ICE vehicles do chemical->mechanical energy conversion. What would it do with all that extra electricity?

A hybrid vehicle could definitely use it, but that's adding Yet More Complexity to an already complex system.

Re:Efficiency as opposed to thermoelectric?

[Nutria]

hydro - none of which require renewing!

You won't be saying that when the drought comes and the river dries up.

Re:Efficiency as opposed to thermoelectric?

[bensch128]

Where is the heat coming from?

It would be great if the waste heat from powerplants (nuclear in particular) could be turned into electricity and used instead of being dumped into rivers and oceans. That's a major problem with modern nuclear plants. If a system like this could be scaled up to those systems, then baseline power generation will probably be nuclear in the future. (Assuming that breeder plants are efficient and security is tight)

Cheers
Ben

Can it really be this good?

[Nom du Keyboard]

This would seem to say that I can take waste heat from my A/C heat-exchangers making them more efficient, and create electricity to drive said system and fans in the process. Given that it's about 100 degrees outside at this moment, this would be sweet!

Re:Can it really be this good?

[Lumpy]

you need a significant heat differential as well as the fact that AC needs fast dissipation to work.

Ac coils need to shed that heat fast, even faster when the ambient temperature is up there like 100degF (I hope you mean 100F and not 100C) This process relies on a wider temperature differential and not shedding it fast.

so it will not work in most places where waste heat energy recovery would be a benefit.

Re:Can it really be this good?

[Steendor]

Maybe it wouldn't work very well in the A/C, but I bet it could be used externally. For a while, my parents had a large thru-wall unit exhausting into an enclosed space, and that space got very warm.

Re:Can it really be this good?

[evilviper]

For a while, my parents had a large thru-wall unit exhausting into an enclosed space, and that space got very warm.

And the hotter that space gets, the more electricity you're wasting on the A/C.

There's really no way to condense waste heat, without expending more energy to do it than you get from the process.

Re:Can it really be this good?

[ultranova]

For a while, my parents had a large thru-wall unit exhausting into an enclosed space, and that space got very warm.

And people wonder why there's an energy crisis... What kind of moron would design something like that ?

Re:Can it really be this good?

[Steendor]

<offtopic>

What kind of moron would design something like that ?

This wasn't ever meant to be permanent; we did this because a long-term construction project kept us from putting it in any of several places that would have been better. We kept the space ventilated as much as possible, but it was still very warm by midday. Incidentally, though I called it a thru-wall unit, it was mounted in a window, not in a hole that was made specifically to receive an A/C.

</offtopic>

I was just trying to make a point: there's no reason the excess heat that an A/C (or anything else) generates can't be caught and put to good use. Just because this is a bad implementation doesn't mean the concept isn't sound.

Re:Can it really be this good?

[Steendor]

There's really no way to condense waste heat, without expending more energy to do it than you get from the process.

There are plenty of things that are powered by heat - indirectly, at least, but probably directly, too. It's just not referred to as "waste" heat until it's left the device and thus can't be useful [to the device] anymore. Surely there's a way to contain some "waste" heat and put it to good use without adversely affecting the efficiency of the device that generated the "waste" heat in the first place.

Re:Can it really be this good?

[evilviper]

Surely there's a way to contain some "waste" heat and put it to good use without adversely affecting the efficiency of the device that generated the "waste" heat in the first place.

That's really only possible at temperatures that are barely higher than ambient. At which point, the amount of power that can be extracted from the difference between ambient and the waste heat is so tiny, that it's practically never worth the investment.

And in cases such as A/C and heating, there is far, far more energy to be saved by using ground-source heat-pumps in the first place, rather than trying to siphon off a little bit of the profuse waste heat from an air-source heat pump.

dude

[Anonymous Coward]

this sounds hot.

yeah, its monday, im retarded.

Massive /. potential

[u-bend]

There's so much waste heat here (Star Wars, Linux, browser, KDE/Gnome debates), that we could power a city and rock out at the same time.

Re:Massive /. potential

[u-bend]

Heh, you think that's funny? How come my 'funny' posts always start off life as 'Interesting?' I mean, sure, I actually have the secret formula for deriving energy from /. flame-wars. Why yes, that is indeed interesting!

Re:Massive /. potential

[u-bend]

OMG, now it's 'Insightful' after a brief stint at 'Funny!' This is cracking me up. OK, back to work.

Re:Massive /. potential

[tepples]

How come my 'funny' posts always start off life as 'Interesting?' Because "Funny" does not award karma. If enough people waste heat and electricity on modding your comments Funny vs. Overrated, your karma can shoot down to Terrible in one comment.

Re:Massive /. potential

[Red Flayer]

that we could power a city and rock out at the same time.

Yeah!! Rock out with our overclocks out!

...or something like that I once heard at a punk show.

Re:First post!! MOD is Coming

[Nom du Keyboard]

My first, first post!

Shortly to be followed by your first modding down into oblivion, no doubt.

Cool idea!

[thewiz]

Er, hot idea!

Um, maybe I should stop now.

Re:Cool idea!

[OldManAndTheC]

Sound idea.

Re:Cool idea!

[Arthur Dent '99]

Soylent Green is peoplicious!

Vegetarians prefer new soy Soylent Green! All of the taste, none of the people!

No efficiency ratings

[denis-The-menace]

How efficient is it?

With double conversions it couldn't be much.

Why not convert heat into electricity DIRECTLY using a peltier device?
(aka Seebeck effect http://en.wikipedia.org/wiki/Thermoelectric_effect )

Re:No efficiency ratings

[drinkypoo]

Why not convert heat into electricity DIRECTLY using a peltier device?

Because peltier junctions are themselves horribly inefficient?

Re:No efficiency ratings

[JavaBrain]

that only works for temperature deltas

Re:No efficiency ratings

[CastrTroy]

Well theoritically, this could be better. If the efficiency of converting from heat to sound was 80%, and the efficiency of converting from sound to electricity was 80%, then it would be more efficient than a thermoelectric device that was only %50 efficient. It doesn't matter how many processes you go through, it's how efficient those processes are. For instance, you can use solar panels to create electricity. And some have an efficiency of somewhere around %5. Now you could also use Coal power to create Hydrogen from water, and use hydrogen to generate electricity, and you'd end up way more efficient than many solar panels.

Re:No efficiency ratings

[Anonymous Coward]

So does this - as stated in the article and any introductory thermodynamics text. You can't do any work without a temperature delta.

Re:No efficiency ratings

[TheSkyIsPurple]

but if the device is giving off 150F heat, and ambient temperature is 90F, doesn't that give a temperature delta?

Re:No efficiency ratings

[Anonymous Coward]

We're already doing that, Coppertop. Go back to sleep, have a steak.

Re:No efficiency ratings

[robgig1088]

Well, unfortunately the plate has a higher specific heat than the air. So once the plate heats up thoroughly, there will be a maybe half degree difference between the two sides. Now if you put ice on one side and something hot on the other, it will produce quite a bit of energy. But its impractical for electricity generation.

Re:No efficiency ratings

[jd]

A car engine is probably hotter than the ambient temperature of the air outside, by quite a lot. Not sure if a peltier device would be a practical heat pump for such a system, though.

It has long occurred to me that (chemical energy released) = (kinetic energy produced in engine) + (heat produced), under the law of conservation of energy, and that (initial momentum) = (momentum of moving components) + (momentum of particles) under the law of conservation of momentum. This means that the system as a whole must now satisfy both the equation for kinetic energy (ke = 0.5 * m * v^2) and that of momentum (momentum = m * v), as must each of the moving components of the engine and all individual particles. Any energy left over that is not accounted for by the components or particles is going to be released as heat and sound. Further, any collisions between the particles and the sides of the engine will not be "perfect" and will therefore convert kinetic energy into sound and heat.

The ideal would be to have an engine designed from the ground up for a very narrow range of conditions, such that the least possible energy is lost in the first place. That is bound to get you better results than trying to do single or double conversions on waste heat. You would then want far more sophisticated gearing, so that the engine will remain within the ideal conditions as much as physically possible.

(Cars with double transmissions are now becoming more common. Since each transmission works on gearing not provided by the other, so that there's always a smooth switchover, and since transmissions can have up to 6 gears these days, that gives you an effective 12-gear system if you do it right. Continuous gearing would be better, but that has never been made effective.)

Alternatively, do away with the whole existing design. It hasn't changed since the days of the Watt engine, except in the case of the rotary engine which nobody has been able to build in a way that is fuel-efficient. Even the rotary engine is an old design, though - 1930s. If you include the engine of the ancient Greeks, that makes for three fundamental designs in the past 2,500 years. It's hard to be impressed, particularly in a day and age of Beowulf and Mosix clusters that can simulate the internal workings of an engine at very high resolution in the basement of any geek with a handful of higher-end machines and a decent interconnect.

Re:No efficiency ratings

[SQLGuru]

Why not take some of these "heat to sound to electricity" tubes and put the solar concentrators on that instead of on the solar cells? Or better yet, use the cells to get their 5%, then use the remaining "95%" heat to drive the tubes......

Layne

Re:No efficiency ratings

[ArwynH]

I won't argue that theoretically it is possible for a process with more stages to be more efficient than one with less stages, but practically that is rarely the case. Take your example for instance, where you are comparing apples to pears. A more accurate comparison of the efficiency of the generation of electricity from the sun would take into account the fact that coal is produced over 1000s of years from plant life, which in turn obtained it's energy via photosynthesis from the sun. As such I suspect the 'direct' conversion of solar rays to electricity via solar panels is quite a bit more efficient than the sun->plant->coal->hydrogen->electricity route.

Re:No efficiency ratings

[Maxo-Texas]

This is an interesting idea relative to Stirling engines.

I wonder if it would be as efficient with less moving parts?

Picture a thousand mirrors, creating a 500 degree hot spot (~400 degree difference) which creates a monster sound that creates a lot of electricity. Would the sound at that intensity destroy the converting object?

Re:No efficiency ratings

[TheSkyIsPurple]

Ah, knew I was missing something in there. Thx!

Re:No efficiency ratings

[El Gigante de Justic]

Also, I believe that part of what they are going for here is the cooling effect provided by the heat engine. While a Thermoelectric effect provides electricity, it doesn't do so as part of a heat sink. Also, I think the "renewable" reference refers to the fact that this could potentially replace solar electric cells, to convert solar energy into electricity, if they can make it efficient enough or cheap enough.

Re:No efficiency ratings

[GreyPoopon]

Why not take some of these "heat to sound to electricity" tubes and put the solar concentrators on that instead of on the solar cells? Or better yet, use the cells to get their 5%, then use the remaining "95%" heat to drive the tubes......

I think that idea was mentioned in the article, but I was very careful not to read it, so I'm not sure.

Re:No efficiency ratings

[OnlineAlias]

This is a small gas turbine engine (you forgot that engine type) combined with a CVT transmission. I believe Volvo has been looking into the exact idea you are thinking of. It died in the early 90's, but as an idea it has always sounded pretty good to me too..

Re:No efficiency ratings

[nasch]

Cars with double transmissions are now becoming more common. Since each transmission works on gearing not provided by the other, so that there's always a smooth switchover, and since transmissions can have up to 6 gears these days, that gives you an effective 12-gear system if you do it right. Coming back to this after yesterday, sorry if it's old news. I think the transmissions you're thinking of are primarily from the VW group. These are not two transmissions, but one transmission with two clutches. Same number of gear ratios, but faster and smoother shifts under most circumstances. And there are 7-speed automatics (these dual-clutch transmissions are mechanically manual transmissions but could be given more gears since there's no shift lever) on the market, with rumors of 8-speeds coming.

Continuous gearing would be better, but that has never been made effective. There are also CVTs on the market right now. I don't know what your criteria are for "effective", but they work.

Re:No efficiency ratings

[putaro]

Continuous gearing would be better, but that has never been made effective.

I've been driving a Honda HRV with a CVT transmission for 5 years now with no problems. I don't think a CVT will handle a muscle car yet but for a daily driver it's great. I've always hated automatics but the CVT is really nice to drive. Doesn't go hunting around for the right gear, feels like the gas pedal is connected to the drive train. I highly recommend it.

I wonder

[Normal Dan]

If it could be used to practically and economically extract the rest of the energy from nuclear waste, which still produces quite a bit of heat. 'Free' power for thousands of years.

Re:I wonder

[Anonymous Coward]

Pfft. Better yet, drop that "waste" into a breeder reactor and extract far more energy out of it, in a much more convenient way.

does it have to

[c0ld4usion]

...come from Utah?

I have not RTFA, but a heat gradient is usually required for these devices. If you have a heat gradient, use a thermocouple.

Maxwell's Daemon Rides Again?

[overshoot]

Unless they're claiming to have found a way around the Second Law, the efficiency of any such conversion is going to utterly suck. My CPUs run less than 10C above ambient, so the absolute Carnot limit on any converter recovering that heat is going to be about 3%.

Why bother?

[1] Thermodynamics, not Robotics

Re:Maxwell's Daemon Rides Again?

[swilver]

Your CPU's run at less than 10C above ambient because it has a huge cooler sitting on top -- the CPU may be cool, but only bacause a lot of heat is extracted from it and pumped out of the system.

Re:Maxwell's Daemon Rides Again?

[indros13]

Even if the efficiency is low, it still might pay off to potentially eliminate the need for a fan, no? Your point is well taken, however. This isn't going to save us from our fossil fuel overlords, merely help reduce power use (or increase generation) on the margins.

Re:Maxwell's Daemon Rides Again?

[overshoot]

Your CPU's run at less than 10C above ambient because it has a huge cooler sitting on top -- the CPU may be cool, but only bacause a lot of heat is extracted from it and pumped out of the system.

That's kind of the idea, no?

I'm really not interested in running my CPU at 100C so that the heat recovery efficiency goes from 3% to 19%, thank you.

Re:Maxwell's Daemon Rides Again?

[byron036]

If the device extracts energy, then the temperature of your CPU will be lowered. Thus replacing the heatsink.

Re:Maxwell's Daemon Rides Again?

[spun]

Yes, but you don't measure the heat difference AFTER the heat has been removed! The Carnot efficiency depends on the heat differential BEFORE the heat has been pumped, yes?

Re:Maxwell's Daemon Rides Again?

[overshoot]

Yes, but you don't measure the heat difference AFTER the heat has been removed! The Carnot efficiency depends on the heat differential BEFORE the heat has been pumped, yes?

You measure the heat difference between the hot side and the cold side of the transfer. In the case of a CPU, between the CPU and ambient.

For more, you really need to understand the Second Law of Thermodynamics and Carnot engines.

Re:Maxwell's Daemon Rides Again?

[Phisbut]

Even if the efficiency is low, it still might pay off to potentially eliminate the need for a fan, no?

Right... so instead of having a light fan noise coming from my box, I should put amounts to be a whistle on the CPU... that'll help!

Re:Maxwell's Daemon Rides Again?

[Anonymous Coward]

Please correct me if I'm mistaken, but efficiency limit of a Carnot engine is not the same as the limit on any energy conversion engine based on a temperature differential; rather it is calculable limit of an engine based on the Carnot cycle which uses volume, pressure and temperature changes of a gas to do work. It is entirely possible that an energy conversion process based on a different principle may be more efficient than a Carnot engine.

That being said, I too am sceptical about the efficiency of such a device, considering that it involves converting heat to sound and then to electricity - just doesn't sound very good at a gut level.

Re:Maxwell's Daemon Rides Again?

[GreyPoopon]

You measure the heat difference between the hot side and the cold side of the transfer. In the case of a CPU, between the CPU and ambient.

Yes, but unless you start VIOLATING laws of thermodynamics, converting heat to electricity actually removes heat from the system. That means (as was mentioned) that you basically replace the heat sink and fan on the CPU with the heat-to-sound-to-electricity conversion device. The net effect (as far as your CPU is concerned) is that the temperature is maintained at somewhere around 10C above ambient and instead of spreading the additional 90C worth of heat (assuming that your processor would hit 100C without heat sink) into the surrounding air, you're using it to generate electricity.

Re:Maxwell's Daemon Rides Again?

[overshoot]

That means (as was mentioned) that you basically replace the heat sink and fan on the CPU with the heat-to-sound-to-electricity conversion device. The net effect (as far as your CPU is concerned) is that the temperature is maintained at somewhere around 10C above ambient and instead of spreading the additional 90C worth of heat (assuming that your processor would hit 100C without heat sink) into the surrounding air, you're using it to generate electricity.

And if all I had was a totally passive system, I'd still have that 10C rise, less 3% power generation. However, that's assuming that the power generator has at least as good a thermal resistance as my present heatsink, despite putting more "stuff" in the path. SWAG: trying to get that 3% will end up costing more in terms of fan power than the same temp rise with a totally passive system.

Re:Maxwell's Daemon Rides Again?

[Anonymous Coward]

Your ignorance is alarming; go away and stay away from any technical discussion. There are many thermo acoustic machines that are silent because the frequency of their pressure waves (EG SOUND!!! CAN YOU HEAR ME NOW!) is beyond the grasp of your primative ears. And believe it or not replacing every PC heat sink in the world to recapture 3% of 50-100W with a small thermo acoustic machine would make a difference. It is puny minds like your own that keep us in the stone age of the ignorant consuming masses.

Re:Maxwell's Daemon Rides Again?

[Phisbut]

  *whoosh*
  # ====   <<--- This is the joke

    o
  --+--    <<--- This is you
    |
   / \

Re:Maxwell's Daemon Rides Again?

[GreyPoopon]

SWAG: trying to get that 3% will end up costing more in terms of fan power than the same temp rise with a totally passive system.

I'm not sure that a fan will be required. Let's see what comes to market in the next eight years. ;)

Link to main site.

[Anonymous Coward]

http://www.physics.utah.edu/~woolf/acoustics/

Good for comps

[eebra82]

I realize this could be a great thing for computers - especially portable computers. However, I am more interested in how large portion of the heat that turns into sound and eventually into electricity. My stationary computer is fine without all that extra power. What I want is to know if this will kill the need for huge fans and actually remove some of the heat, or if it will just suck a small portion of it.

Re:Good for comps

[Anonymous Coward]

You'll probably still need the huge fan to get the heat TO the device, a set of earplugs for the noise, and a lot of space in which to put it.

Re:Good for comps

[g8oz]

I think a better direction for heat sinks is the use of carbon graphite foams.

Use in autos?

[evildarkdeathclicheo]

Since the internal combustion engine is really a noisy heat pump, wouldn't this be of use in hybrids, or perhaps as an alternative alternator? (alternatator? alternatatoe?) Perhaps in the cubicle farms of tomorrow, we'll all be sitting on these heat-powered piezo tubes and fed a diet of beans to power our own workstations.

Re:Use in autos?

[SQLGuru]

If you put these things in the cubes of the sales force, you'd get a lot of hot air *AND* sound.......you could power the whole world. And then there's always the fertilizer/bio-fuel that is coming out of their mouths.

Layne

to heck with "waste" heat...

[dAzED1]

if they can actually do this, then set up massive arrays of it on top of active volcanoes and other natural heat sources. As the claim is they end up with electricity, that means there is less heat, and we have this maybe/maybe not global warming thing going on. Seems we can reduce a lot of the natural warming of the earth's atmosphere with something that can do this, if it really can...

Re:to heck with "waste" heat...

[woolio]

if they can actually do this, then set up massive arrays of it on top of active volcanoes and other natural heat sources. As the claim is they end up with electricity, that means there is less heat, and we have this maybe/maybe not global warming thing going on. Seems we can reduce a lot of the natural warming of the earth's atmosphere with something that can do this, if it really can...

Yes, but can you imagine the environmental effects caused by cooling a volcano at "Faster-Than-Nature-Indended" rate?

The environmentalists would raise hell!

Re:to heck with "waste" heat...

[Anonymous Coward]

Since the electricity would be used to power devices that would ultimately just produce heat, there would be no net cooling.

Also, geothermal electrical generation has been around for some time using steam turbines. Unless this is more efficient, there's not much point.

Re:to heck with "waste" heat...

[dAzED1]

Since the electricity would be used to power devices that would ultimately just produce heat, there would be no net cooling.

There's going to be a set amount of electricity usage. I'll still turn on the lights in my house, for example.

Now, if that electricity can come at the cost of cooling down a volcano, then hey! But currently, it comes from burning coal. If you don't understand the net difference there, then I'm sorry the education system has failed you so badly.

Dog Whistle

[Apocalypse111]

Symko says the devices won't create noise pollution. First, as smaller devices are developed, they will convert heat to ultrasonic frequencies people cannot hear.

So now we've turned my car into a mobile dog-whistle, causing even the well-behaved dogs to bark at me.

Ooh, on the other hand, maybe we could get the sound into the frequency range at which various crystal wine glasses shatter... I've got some asshole neighbors who could do without those particular bits of glasswear.

Re:Dog Whistle

[Anonymous Coward]

"Bits of glasswear"... sounds painful.

Diaphragms?

[bigattichouse]

would it be possible to do something with a speaker? (as an experiment). I understand TFA about the piezeo devices being compressed/released by the plates vibrating like a flute, but I started wondering about the image that immediately popped into my head, of tuned diaphragms responding to air pressure differences to vibrate a coil... I guess if you did the flute thing, you could just put a piezo crystal between a tuning fork and a solid surface... every note at that frequency, especially if sustained, would then make power.... So, how about making great huge "moaning towers" out in the middle of nowhere that do the same thing? I'll call it "BULLROAR"(tm) technology. Hell.. I wonder if the forces involved on a bullroar spinning aroud your head might generate power (say, with a couterweight like thos rechargable watches). This idea is kinda fun.

Re:Diaphragms?

[jbeaupre]

Piezos work well when motions are small or in a compact area. They can put out fairly high voltages for the motion involved. Coils handle large motions better. It may just be that piezos are better in this case. Or maybe they got a good deal and had a bunch laying around.

Another reason may be that the motion of a diaphram/coil means you are continuously changing the resonant tube length, creating non-linearities. In other words, you couldn't set up a decent resonance because the dang chamber keeps changing shape on you. Piezos would deform less and create less non-linearity.

But this is from Utah

[shis-ka-bob]

In the land of Cold Fusion, normal laws of physics don't seem to apply. This is only a problem when the rest of us try to replicate the results without access to divine intervention (e.g. from locations out of line of site of the Mormon Tabernacle)

Re:But this is from Utah

[Anonymous Coward]

Nice bigot blast. BTW University of Utah isn't the Mormon school. That is where a lot of the people that don't like the Mormon Church go. BYU and Utah State are the heavily Mormon schools. Now U of U is the school of cold fusion fame but that has nothing to do with the Mormon Church.

Re:But this is from Utah

[CodeShark]

Yabut...

I'm out of line of sight from Utah. Using a CRT based device. Transmits electrons using Wifi. Can do pictures. Even tunable video streams at set frequencies...

Ever hear of television? Invented in Utah -- see Philo Farnsworth in Wikipedia if you don't believe me.

So your statement about Mormon anything is nothing more than a bit of religious flamebait...

Re:But this is from Utah

[malvidin]

The room that Pons (of Pons and Fleishman Cold Fusion fame) work in was far from the line of sight of anything. It was in the basement of the University of Utah chemistry building. The engineering building this research was done at is at least a half mile away.

Yes, I know you were joking, but Fleishman wasn't from Utah.

Re:But this is from Utah

[shis-ka-bob]

I'm still pissed off that I had to be working at a DOE lab when F&P came out with the cold fusion crap. Several DOE labs had to spend millions of tax payer dollars investigating the nonsense. If the same school is still making claims about energy sources, lets just say that I am very skeptical. Yes, I do agree that my rant was unfair.

Rube Goldberg Rejoice !!

[Timtimes]

Why not add a few other links in the conversion process just to sound even sexier? Efficiency is so pre 9-11. Enjoy.

cooling computers?

[gEvil (beta)]

I'm not sure about you, but when I spec parts for computer cooling, I'm looking for something that's cool AND quiet. I don't want whatever device to be creating extra sound in it's quest to cool more efficiently.

Re:cooling computers?

[bar-agent]

I don't want whatever device to be creating extra sound in it's quest to cool more efficiently.

According to the article, by the time they are shrunk down enough to be usable in a computer, it'll just be ultrasound. Hopefully, it'll be ultra enough to be outside of even a dog's hearing range.

Re:cooling computers?

[rts008]

So then it will annoy bats instead of dogs?

Batman may not like this, and when Batman is not happy, Gotham is not happy!

Finally!

[Anonymous Coward]

We might finally get an answer to the age-old question:

"if a tree falls in the forest and nobody is there to hear it, does it make any noise?"

just hook this thing up to a little device that can text you once it's running.

use it to power my computer

[Anonymous Coward]

It could be connected to the heat sink on the CPU, hard disk, and on the LCD backlight. The resultant energy could be fed back to the computer to recover the lost energy reducing energy consumption. If it could be made to be 100% efficient, the laptop could work forever on a single charge! Of course it could also draw energy from the lap on which the laptop is sitting (correlation in heat versus sites visited).

Wait, I didn't post that... oops.

Please see my patent for "A Method of Recovering Waste Energy and Extending the RunTime of Electronic Equipment".

Also the patent for "A Method of Continuously Powering a Computer Laptop from Waste Heat".

Re:use it to power my computer

[ThosLives]

I've always wanted to try using the thermal dissipation of the processor to power its own cooling system. That is, create a pressurized case, and have an intake compressor that brings in cool air, which is heated by the processor(s), which is then sent out through a power-tapping device (turbine or piston) to power the compressor and keep things going.

Basically a Brayton-cycle cooling system. You could actually move a lot of air with 300W power dissipation! (way more than you can with a little 15 W cooling fan).

(Too bad the drawbacks are that it requires some pretty slick machinery and a pressure chamber :p )

Hype - Second Law has not been repealed.

[Palmyst]

More stages of energy conversion = more waste. That is all.

Re:Hype - Second Law has not been repealed.

[WebCowboy]

More stages of energy conversion = more waste.

Well, where I live most electricity is generated as follows:

1. Energy stored in coal->heat energy through combustion
2. Heat energy->mechanical energy through use of steam to drive a turbine
3. mechanical energy->electrical energy through the use of a generator attached to the steam turbine

There is also natural gas, which simply takes the place of coal and uses the same number of energy conversions, and nuclear power, in which step one is simply changed to "energy stored in Uranium->heat energy through nuclear fission". Same number of conversions for all of that, except that step 1 is more efficient (less waste energy loss).

Now there is also "tree hugger power" - hydroelectric, wind and solar generation which may have fewer conversions, however the efficiency is lousy! You need huge, environment-destroying dams or you need to bulldoze thousands of acres of nature to put up windmills or solar cells. Why stop global warming if we have to destroy nature to do it, right?

Well, here we have a new solution:

1. stored energy -> heat through whatever process (combustion, fission, fuel cell, even waste heat from other processes)
2. heat -> sound with these new "prime movers"
3. sound -> electricity through piezoelectric effect

There are exactly the same number of steps/energy conversions as with the way we make power now, except now we have vastly more efficient replacements for the last two steps--something we haven't seriously had! The overall efficiency of such a a system is the product of the efficiencies of all the steps, so we could make great gains with such a process. This technique could be used to replace solar panels as well, because even though solar panels do direct conversion, they only convert 12 percent of the solar energy they capture into electricity. In order to match performance of traditional solar panels each step need only be 50 percent efficient (.5 * .5 * .5 = .125). Thermal solar collectors can readily be made to match or exceed that and apparently it is achievable with these sound tubes and piezoelectric pickups. Though it is while off, this is definitely more than hype and does not rely on violating the laws of thermodynamics in order to be a viable method of electricity generation.

Re:Hype - Second Law has not been repealed.

[condensate]

Shesh. I was afraid I would never find an article touching the second law in this discussion. C'mon. In easy terms: You can't win! If you want to use waste heat, you need to cool something else in order to heat it up again with that same waste heat. This costs you energy that you need to take from somewhere. Even if you would use part of that waste heat, efficiency would go by the board. You cannot turn heat completely into mechanical energy (sound) your efficiency drops well below 100%. If you turn sound in turn into electricity, part of the sound energy dissipates (second law here again, in another form: If you disrup something - which you do with pressure waves such as sound, you increase entropy. If you increase entropy - well - it heats up... That is in fact another statement of the second law). So full ACK to the parent you just waste more. Question is not how efficient is it, but how efficient is the process compared to everything else. Seeing that I did not yet read TFA, I shall now do so, in order to maybe find an answer to that question.

Re:Hype - Second Law has not been repealed.

[Chris Burke]

Uh unless you can take advantage of more efficient conversions resulting in an overall reduction in waste of course. You know, if the efficiency of heat->sound times sound->electricity is more efficient than heat->electricity, then you win. A single conversion of 1% efficiency is worse than a hundred consecutive conversions of 99% efficiency.

All the Second Law tells you is that no stage of conversion can be 100% efficient. It does not say that any particular conversion path is more or less efficient than any other.

Interesting but low on power production?

[CodeShark]

AFAICT the "power" production is related to the fact that they have created a way to get vibration from a temperature rise at a given "resonant" frequency in a tube. Cool but there still has to be a heat rise -- and the power out is limited by the Carnot law to 1-(Temp Low/Temp High) in absolute temp units. So with a 90 degree fahrenheit heat rise, for example, the maximum efficiency (using room temp as t low) of about 14% -- the actual output is probably lower. Or about the same as current generation not-very-expensive thin film PhotoVoltaic cells.

So as a solar source these devices are most likely a bust -- I just don't see a tube + device + piezo type of setup beating the think film. Leaving a question for the researchers -- how many devices over what area would be required to utilize these as a bottoming cycle for a small power plant?

Re:Interesting but low on power production?

[Overzeetop]

Don't necessarily discount solar sources. Solar can produce quite a bit of heat, and being able to produce power from a 500-700F element could feasibly produce 30-40% efficient devices if the acoustic conversion is highly efficient. One poster mentioned poor output, with high voltages and small current, but a parallel set of such devices might deliver a net current that is into the useful range. Even 30% of 1200W/m is a nice return. I suppose it depends on the longevity of the components at higher temps and the cost to manufacture as to whether the net value is enough to make it commercially viable.

I know that solar farms have been built with a central heated tower (very cool looking, if not terribly efficient and subject to large fires stirling cycle?), but this might allow a bunch of independent modules and would tend to fail gracefully, since running a larger number of units in parallel would allow for individual units to fail without taking the whole system down (I would hope).

Slow down everyone

[scottennis]

This is from the same institution that brought you cold fusion (not the markup language) a few years back.

I'm just sayin' . . .

In Related News...

[DaveWick79]

Sources in Washington DC claim to have found a way to power 73% of the nation's capitol while nearly completely reducing the greenhouse emissions from the capitol building. Within a few years, planners expect this new energy source to power the entire city as well as the capacity to sell energy to surrounding areas.

Re:In Related News...

[Anonymous Coward]

Sources in Washington DC claim to have found a way to power 73% of the nation's capitol while nearly completely reducing the greenhouse emissions from the capitol building.

Converting the hot air coming from the politicians into sound? Sounds like a perpetual motion machine. And if production gets low just add some ethanol? Can't wait for the spin on this.

Re:In Related News...

[jbeaupre]

A funny aside: years ago the company I worked for launched an initiative asking for energy saving ideas. I suggested that every time corporate headquarters comes up with a new initiative, we shut off their HVAC for a week.

Sadly, it wasn't implemented.

World's Largest Crack Pipe

[Anonymous Coward]

I don't know about anyone else, but the photo accompanying the linked article looks like that guy is firing up the world's largest crack pipe!
Only we can't see who's toking on it.

Skunky

Cooling

[malvidin]

I remember visiting a friend there who was working on this project. He mentioned that they were using tuned sound to cool devices. The inverse is what they are talking about here. Going either way there will be losses, but without looking at the data I can't make any observations about efficiency. I guess I could call and ask for more info...

Less heat is good...

[FlyByPC]

...as long as the sound-conversion part doesn't leak too much. My workstation already sounds like a jet engine.

Why not Sterling Engines?

[RealBothersome]

Why not just use a Sterling Engine? http://en.wikipedia.org/wiki/Sterling_engine
They convert heat to motion/torque directly.

Re:Why not Sterling Engines?

[youngerpants]

Hmmm, that picture of the Stirling Engine in the Wiki article you referenced reminds me of something... I just cant seem to quite put my finger on it.

Re:Why not Sterling Engines?

[curlynoodle]

Moving parts decreases efficiency and reliability.

YOU NEVER LISTEN TO ME!

[Anonymous Coward]

/love you dear.

Heat to Sound to electricity.

[malvidin]

Well, luckily my wife doesn't need to be loud. She's that hot.

Re:Heat to Sound to electricity.

[Anonymous Coward]

SWEET

Re:Heat to Sound to electricity.

[jbeaupre]

This is Slashdot, which means we have to double check whether you are actually married or what you mean by hot. Let's hope you mean online "wife" and not that you set your real wife on fire.

Re:Heat to Sound to electricity.

[pan_piper]

Well, luckily my wife doesn't need to be hot. She's shocking.

Re:Heat to Sound to electricity.

[Anonymous Coward]

This thread is useless without pics

Re:Heat to Sound to electricity.

[StikyPad]

Well, luckily my wife doesn't need to be shocking. She's battery powered.

Re:Heat to Sound to electricity.

[zolaar]

Well, luckily my wife doesn't need to be shocking. She's mute.

Re:Heat to Sound to electricity.

[Nullav]

Well, luckily my wife doesn't need to be shocking nor hot. She's inflatable.

Re:Heat to Sound to electricity.

[Jarik_Tentsu]

Does that mean there is a relationship over a wife's hotness...and how much sound she produces?

And does it work the other way? Ie, transferring a wife's loudness into hotness. =P

Re:Heat to Sound to electricity.

[dhammabum]

Well, luckily my wife doesn't need to be shocking. She's battery powered.

Well, if she is a battery hen, you could just setup a biogas generator.

amount of electricity per heat unit?

[192939495969798999]

It doesn't indicate what amounts of electricity could be retrieved, from what I read, but it almost wouldn't matter if it was cheap enough to build. You could blanket death valley with these things, and at least on summer days generate enough electricity to offset grid saturation by excess a/c units in some large area (hopefully large enough to justify the cost).

Re:amount of electricity per heat unit?

[Anonymous Coward]

You still need a temperature differential. Where does that come from in Death Valley?

Re:amount of electricity per heat unit?

[192939495969798999]

the diff between day and night temperatures is extreme, same with temp between in sun and underground, either would work with right equipment.

Just a little prob with the numbers....

[Ancient_Hacker]

Nothing to see here. It's just a Prof that's spent $2 million on a wild goose chase. Now with the great smell of fish! The rub is multi-fold:

• Good old Carnot's law. The efficiency is limited by the temperature drop across the device compared to the absolute temperature. Now take two thermometers, stick one up your butt and fart. compute the temperature difference. Divide by 483. That's your efficiency in converting heated gas into sound. Prolly about 0.005% as a rough approx.
• For a less gross example, pucker your lips and blow. Do this for five minutes or until you pass out. You probably feel warm-- that's the heat. How much acoustic power did you generate? Well a loud whistle is about 100dbA, about a hundredth of a watt. Efficiency, 0.004% at best.
• Piezoelectic efficiency. Well, it's really high-- for an acoustic transducer. The Interwebs seem to reveal no figures for this, and in general a high level of coyness is a way of hiding embarrasing numbers. Let's assume a best-case number of say 40%.
• The impedances. Crystals are very high impedance devices, putting out LOTS of volts at vanishingly small amps, which is bad news for us, as most of our power sinks are low impedance. Getting a few milliamps at 40KV is not very compatible with powering your laptop, which is about a million times lower in impedance. It's particularly inconcvenient converting tens of kilovolts downwards with economy and efficiency.

So sorry, probably much less than nothing to see here, just another bundle of our taxpayer's money spent on a totally pointless technical exercise.

Re:Just a little prob with the numbers....

[Spy der Mann]

You said:

How much acoustic power did you generate? Well a loud whistle is about 100dbA, about a hundredth of a watt.

From the article:

When heated, the device generated sound at 120 decibels -- the level produced by a siren or a rock concert.

Assumming many devices can be put to work in parallel, it might not be a wild goose chase after all. Just imagine how much waste heat ALREADY GENERATED (i.e. in car engines) could be reused into electricity. That would make your car more energy-efficient, since you wouldn't need to use more gas to play your latest MP3 on the car stereo.

Re:Just a little prob with the numbers....

[jbeaupre]

Just read about piezo efficiency the other day. 60% is pretty common for polycrystalline. 90+% for single crystal. I'll hunt down the link if you're dieing to read about it yourself.

Re:Just a little prob with the numbers....

[Anonymous Coward]

It will be kind of annoying listening to your MP3s over all the 120dB noise generated by this device. Or to hear that noise going on while you're driving and generating heat. Most people prefer quiet vehicles, I think.

Re:Just a little prob with the numbers....

[Ancient_Hacker]

>When heated, the device generated sound at 120 decibels -- the level produced by a siren or a rock concert.

Well whoopee-ding.

So they get one watt of sound power.

Now how many watts of heat did it take to generate that one acoustic watt? Deponent sayeth not.

General Carnot principles suggest a whole spitload of watts.

In general converting random motion, the lowest quality of energy, into periodic sound waves, a MUCH higher quality of energy, never happens by chance or with any notable efficiency. That principle has been known for going on 175 years now.

Now feed that very expensively obtained watt into a most efficient piezoelectric microphone. Microphones rarely go above 2% efficient.

To be sure, measure the temperature drop. I suspect you'll be lucky to get one degree of drop. Out of 480.

Divide that by the heat to sound efficiency and you get a number with an amazing and uninteresting number of leading zeroes.

I'll eat several hats if the heat to electricity efficiency factor exceeds 0.001

Even a Stirling engine can do better, and even that is totally useless.

Re:Just a little prob with the numbers....

[wsherman]

It's just a Prof that's spent $2 million on a wild goose chase.

Well, given that the USA is spending about $10 million an hour on the war in Iraq and considering that the USA's interest in the Middle East is mostly about energy (specifically oil), I'd have to conclude that solving the USA's energy problems is rather important.

Compared to the cost of the Iraq war, $2 million for some obscure research into energy technology doesn't sound too bad.

Good old Carnot's law. The efficiency is limited by the temperature drop across the device compared to the absolute temperature.

Well, if this Prof's sound-based device actually achieved the maximum Carnot efficiency with no moving parts and a size that could fit into a pocket then that would be a breakthrough worthy of a Nobel prize. Now, given that the Prof (or one of his grad students) is shown heating the thing with a blow torch, I'm guessing that the device doesn't actually come close to the maximum Carnot cycle efficiency.

Still, as long as the Prof is honest and is willing to explore the inherent shortcomings of the technology, there is the potential for him to generate some previously unknown results which would be valuable in solving the USA's energy problems.

Re:Just a little prob with the numbers....

[radl33t]

Even a Stirling engine can do better, and even that is totally useless. Care to explain? I would argue that a Stirling cycle device can claim a higher efficiency than the venerable modern gas turbine. A mass produced free piston device would similarly outmatch a gas turbine in reliability & maintenance, manufacturing cost, and lower vibration & sound output. It would do so while burning anything, funny fuel, garbage, or people like you. They could probably not compete on power/mass (e.g. airplanes), but some would even argue that. Of course, gas turbines have enjoyed a nice head start.

Re:Just a little prob with the numbers....

[cool_arrow]

I remembered reading about this Stirling powered sub sometime back: http://www.kockums.se/Submarines/aipstirling.html

Re:Just a little prob with the numbers....

[Anonymous Coward]

The question then becomes whether the recovered energy from the car engine would ever exceed the energy embodied in the construction of the device to recover this energy. If not it has an EROEI of less than one. This doesn't immediately mean it is useless as there may be applications where an overall negative EROEI, if it delivers power where you really need it, is still worthwhile, but it does mean that you need overall more energy to make and use the device than you get from it.

Re:Just a little prob with the numbers....

[Ancient_Hacker]

>I would argue that a Stirling cycle device can claim a higher efficiency than the venerable modern gas turbine.

??? Argue all you want. A quick search of this "InterWebs" thing shows a LOT of argument about Stirlings. But you'd think after 200+ years of development there would be maybe at least just *one* working example where the efficiency was measured and usably high. Hmmm ......

Re:Just a little prob with the numbers....

[Anonymous Coward]

It's particularly inconcvenient converting tens of kilovolts downwards with economy and efficiency.

So THAT'S why we transport basically all our electricity in tens to hundreds kilovolts range.

Re:Just a little prob with the numbers....

[Ancient_Hacker]

>Compared to the cost of the Iraq war, $2 million for some obscure research into energy technology doesn't sound too bad.

Apples versus horsecollars. Not a logical or illuminating comparison.

And research into obscure areas is just fine, but there are plenty of areas that are not hopeless squared. This one

Re:Just a little prob with the numbers....

[radl33t]

I thought for a moment you knew what you were talking about. After learning you do not have a clue, I no longer feel threatened. But then I guess I could have foreseen this, anyone with a basic understanding of thermodynamics would understand the strength of the Stirling cycle. Couple that with a basic knowledge of manufacturing and materials and you would fully understand the advantages over engines based off other cycles and why development has taken so long to get going (and for economic reasons likely will never challenge other programs). A short summary! 1) Serious Stirling development did not start until the late 1970s (See, GE, Phillips, MD ( Boeing), NASA ) 2) Brayton, otto, rankine, and diesel cycles had a very large head start on this development 3) NASA's radioisotope Stirling engines for deep space have efficiencies exceeding 45% in the package the size of a Diet coke. All of this can be easily substantiated if you actually visit a library (GASP!), but I understand this concept might be foreign to you. Specifically one in a large University that allowed you access to all the journals, NASA reports, and company/contractor reports that detail these developments.

Re:Just a little prob with the numbers....

[Ancient_Hacker]

The only number in your posting is "45" (percent), and it's wrong.

Searching the InterWebs finds a NASA press release quoting 20% efficiency. And that's with a deadly radioisotope that can supply 860C heat.

To believe Stirling cycle is superb you have to posit huge scientific industrial conspiracies, heretofore unachieved progress in bizarre materials, and quite a bit more. Lotsa luck.

Re:Just a little prob with the numbers....

[Ancient_Hacker]

That's swell. However in military applications like this one they went with the Stirling as it's QUIET, not because of its efficiency (which is low). So low it's hard to find numbers. The ones in the technical peer-reviewed papers are around 3%. The ones in the glossy PDF's from places with "stirling" in their name are heavily caveated numbers around 50%. Guess which number I'd consider more reliable.

Re:Just a little prob with the numbers....

[radl33t]

I am glad that you can correctly estimate the required hot end temperature. However, you are off by a few degrees. Hint, deep space is cold.

There are no conspiracies needed. It is simple economics. There is no economic incentive to recreate the billions of dollars invested in other technologies for what would be marginal improvements in performance and reliability. At this point, materials limitations are constraining all heat engines... Temperature for temperature, a Stirling device can hit a higher efficiency as evident by any basic thermodynamic analysis.

With that in mind, Stirling devices are probably economicly regulated to niche roles. I'm not deying this and I am not insinuating any conspiracy against science, other than the unfortunate ramifications of our economic system.

Your reliaince on the Internet as a sole source for information is disturbing.

I'm not sure how ignorant you must be to catagorically define radioisotope as 'deadly'. The technology is very mature and has been used for decades to power thermoelectric devices. Furthermore, the beauty of heat as an input means that the Stirling device can aquire that hot end temperature by any means necessary including: concentrated sunlight, nuclear decay, fisson, combustion, or even one day fusion.

To be absolutely clear, my original response was a challenge to your claim that Stirling cycle devices are worthless. This is evidently not the case (unless you are intellectually confined to google searches). Their worth is slowly being realized for specific applications, such as Stirling Dish arrays and distributed CHP systems, and of course for power conversion on space systems. The exploration by NASA should clue you into the fact that the technology is real but economically constrained.

Re:Just a little prob with the numbers....

[radl33t]

The ones in the technical peer-reviewed papers are around 3%.

This is a blatant falsehood and indicates that you are clearly incapable of an objective assessment.

Yes, many Stirling engines have low efficiencies, but this isn't a technical defect. On the contrary, Stirling cycle is chosen because it offers the highest performance for a given deltaT. The deltaT serves as the constraint. Combine this with the benefits of cheap manufacturing and reliable operation and it becomes clear that Stirling is a research interest for small deltaT endeavors.

Perhaps you should actually check in with the literature, instead of make pretending. You will find numerous examples of Stirling engines of all sizes and types ranging from less than 1% efficiency to well over 30% efficiency. Similarly, you can check the literature for other heat engines and compare performance based on deltaT. If you do this you will see that you are wrong. As I have little stake in whether or not you believe me I will not do this leg work. I present the challenge so that other readers are not mistaken by your mis information

Then of course you could go into the refrigeration/cryocooler literature to discover how successful the Stirling cycle has become for heat pump applications. I again challenge you to make the appropriate efficiency comparisons with other technologies

From the language of your posts it is clear that you are educated. To be this stubborn against something you clearly have not investigated and don't fully understand is alarming and unfortunate. Please take my challenge and be open to the possibility that your superficial assessments, could in fact, be wrong.

Re:Just a little prob with the numbers....

[radl33t]

Do not let the other response fool you. Stirling designs have been developed for subs. I believe they are the same engines people are now trying to use for solar applications (of course modified).

The other response was partially correct, Stirlings are excellent because they are much quieter and their "white noise" is much less of a concern than the rumble of a diesel. However, the Stirling machines also have similar efficiencies to traditional diesel cycles and of course have a higher theoretical maximum efficiency.

Re:Just a little prob with the numbers....

[JoeSchmoe999]

As far as your #3 point, according to the Smithsonian Institution, piezoelectric crystals, and specifically quartz crystals can reach 95% efficiency in converting mechanical energy to electrical energy.

http://adsabs.harvard.edu/abs/1984PhDT.........9E

Re:Just a little prob with the numbers....

[Ancient_Hacker]

Okay, let's go with: you're right... So for some unfathomable reason this wonderful Stirling engine with soo many benefits not to mention rumored efficiency has not made the slightest splash in the real world.

Conspiracies? CIA plot? Vooodoo?

Then again there's a cult of "scientists" that know with a small deltaT, you have a miniscule top efficiency. Been known to these cultists for centuries. On top of that loow theoretical efficiency, you impose the intrinsic inefficiencies of the Stirling Cycle, where hot and cold sections are mostly intermingled, leading to tremendous heat losses. Miniscule times teensy gives almost vanishing results. There are few Stirling engines that could even pay the interest on their original cost, even with a free source of heat.

Ergo they've been looked at every few years, then discarded by these fanatic scientists and physicists.

.... or it's a CIA conspiracy

Re:Just a little prob with the numbers....

[radl33t]

Wow, I read some of your other posts on other topics. It is sad to see someone seeminginly so educated behave this way. Everything I've said is supported by the prevailing opinion in decades of published literature. My challenge stands for you to actually find this out for yourself. I'm not really sure if it has been your intention to troll. Either way, I stand behind my posts and enjoy seeing them contrasted by yours.

Re:Just a little prob with the numbers....

[Anonymous Coward]

Sigh, "a stirling engine can do better"...
It's quite clear that you didn't grasp this at all. This is a frickin' stirling engine, given that travelling wave engines utilizes the process of a stirling cycle. Not that this is particulary novel, it's pretty much been done in variations since the mid 50s. Efficiency improvements and making them small enough to be usable to chill electronics would be nice though.

This isn't meant to replace an ICE or a turbine+generator, it's meant to replace a small fan and a heatsink.

Re:Just a little prob with the numbers....

[Ancient_Hacker]

It's touching, in this age, to see someone with such firm faith. Faith, I say, because you havent provided a single verifiable fact, so it must be 100% pure unalloyed Faith.

Lotsa Luck,

Global Warming

[Anonymous Coward]

So, global warming is a boon? We now have a renewable source of energy!

so what you're saying is...

[Anonymous Coward]

I can hook this device up to my wife's ass and use it to power a small fridge for my beer? Even though that would be nice, I would much rather they spent valuable R&D time on something the average man could use. How about a mute button for afforementioned wife? MY KINGDOM FOR VOLUME CONTROL!

Re:Finally...

[The_Wilschon]

You think Steve Ballmer is hot? Ewwww

This ars article might be something similar?

[vecctor]

I was trying to figure out where I had seen something like this recently:

http://arstechnica.com/news.ars/post/20070527-new- stove-generator-refrigerator-combo-aimed-at-develo ping-nations.html

this thing also uses thermoacoustic technology.

Wireless power!

[Anonymous Coward]

1) Build giant amplifiers/speakers at power plants
2) Power remote villages without difficult constructions
3) ???? Profit !!!!

Depends how you define waste

[Colin Smith]

I believe the key point about the device is the lack of moving parts. A steam turbine for instance has a shit load of highly expensive moving parts to make it work.

Cold Fusion

[ISoldat53]

Isn't this the same group that brought us cold fusion?

Re:Cold Fusion

[FoXDie]

Allaire?

Re:Cold Fusion

[Ex-MislTech]

yup ...same ppl, thou....you might take a 2nd look at what is happening
with the ppl that were working with cold fusion.

http://video.google.com/videoplay?docid=2229511748 333360205&q=heavy+watergate&hl=en

Even the navy at the SPAWAR facility in san diego are replicating the
experiment now.

I bet it could do infrasound too

[spun]

We could tune it to the brown note!

Depends how much it costs.

[Anonymous Coward]

It depends how much it costs. If the cost of implementing and using it is low enough, it doesn't matter if the efficiency is low. This is waste heat that is currently being completely discarded.

Even Better

[Orig_Club_Soda]

Figure out how to turn sound from the inner city, construction sites, and freeways in to electricity. There is so much noise pollution out there, this would be practically free.

Could you image: singing to your flashlight to keep it lit!

This is the mechanism

[Anonymous Coward]

This IS a stirling engine. Specifically, a modification of the thermoacoustic stirling engine originally developed at LANL.

Are these the same guys that

[recharged95]

did the cold fusion "breakthroughs" back in the 90's.

Man, I need to goto that school, they must be smoking some good stuff.

In the end, more heat = more energy = more heat. Entropy r0cks!

What people are missing here...

[Anonymous Coward]

...is that these appear to be PASSIVE devices. They generate the sound and electricity from it with no input other than the heat gradient.

Also, as they were built by PhD students, they are probably not very expensive to manufacture.....especially if you were looking at mass-production.

While the efficiency may be low compared to some technologies they can be used to collect electrical power from any heat source (of more than just a small temperature difference) regardless of whether that source is natural or waste heat from a man-made device.

The question is really if they can make a commercial thermoelectric plant utilizing this principle, not if it can cool a CPU.....

Free energy via the folks at University of Utah?

[jpellino]

Pardon my skepticism.

Seems easier to just put the sound > em units on every street corner in every major city.

And strapped to every 4 year old.

Why not use a solid-state Pelier instead?

[macraig]

Some Slashdotters have doubtless use Peltier devices to try to chill their massively overclocked PCs, but that's only one application of them: they can also be used in reverse to generate electricity from a thermal differential. I don't know how the efficiency would compare to this - an actual efficiency wasn't mentioned in TFA and I've never used a Peltier in this fashion - but I suspect it might be comparable. There's also the absence of moving parts to consider, too.

More efficient use of heat rejected from HVAC

[Elfich47]

Try a direct heat exchanger from your Air Conditioning system to pre-heat your hot water. Much more efficient.

http://www.thermastor.com/Heat-Recovery-Water-Heat ers/

Re:More efficient use of heat rejected from HVAC

[Nom du Keyboard]

Try a direct heat exchanger from your Air Conditioning system to pre-heat your hot water.

Do you know how much hot water I use on days like this? Almost none!

Re:First post!!

[Anonymous Coward]

Congratulations, you're scum. Go troll on another site.

Maxwell's demon

[Anonymous Coward]

hmm... This doesn't involve a little guy watching the molecules, and letting the fast-moving ones through a little door does it? (This being /., naturally I haven't rtfa.)

In this house, we obey the laws of thermodynamics

[Anonymous Coward]

So they've invented a new type of thermal engine.
It's a neat toy, but anyone saying they will help efficiency by converting waste heat to electricity is FUCKING LYING.

Why do you have waste heat in the first place? Because you were using some other form of thermal engine in the first place, and the efficiency of that thermal engine depends on the ability to DUMP WASTE HEAT.

So you put the gadget in to convert waste heat to electricity, you reduce the efficiency of the main engine.

You can't get something for nothing.

Heat is renewable

[paladinwannabe2]

The sun produces heat. If solar and biodiesal are considered renewable, so should this.

Prime Real Estate

[Herkum01]

Now we only have to install two in the US. One in the Capital Building (where Congress meets), and the White House (where Bush lives). All the hot air and excess sound should surely power the US for years to come.

University of Utah?

[Wormholio]

University of Utah? Why would they need this, they have cold fusion working there.

Current thermopiles are pretty low efficiency.

[Ungrounded Lightning]

What are the advantages to converting the heat to sound first, rather than directly to electricity via thermoelectric processes?

Current thermopiles are pretty inefficient. The main problem is that they unavoidably leak heat from the hot to the cold side. In peltier cells (the ones in those cheap "coolers" and CPU heatsinks) leak several times as much heat as they make use of when running as generators (and leak most of the heat they pump, so they have to pump it several times to get it dumped). There's a more efficient one in the labs, which doesn't have a lot of charge (and thus heat) carriers in the hot/cold bridge. But it's still far from perfect.

They also have to operate at temperatures that don't destroy their materials - typically semiconductors. That limits how hot the hot end can get, and thus how much energy you can get out of the heat (since they can't break the carnot cycle rules).

These devices are gas-working-fluid heat engines, with the gas (and the piezo power takeoff) as the only moving part(s). In principle the gas "prime mover" should be able to approach carnot cycle efficiency (which is as good as you CAN get) - and that's what this group is trying for. Being made of gas and metal, the "hot end" can get very hot, too, so you aren't as limited as with semiconductor heat converteres. Meanwhile, piezos are extremely efficient as well - and some (like quartz) can also handle very high temperatures.

As simple mechanical systems they should also be easier to fabricate than semiconductors, making them a garage-shop item that doesn't require your garage to be a clean-room in silicon valley with 100 megabux of specialized equipment.

loud exhaust now fashionable?

[Anonymous Coward]

and now harley's will be hybrids part gas, part electric

Re:"University" of Utah

[Anonymous Coward]

Mormons aren't Christian.

Zen and the art of Power Generation

[Anonymous Coward]

So does this mean that by skipping the first step, I can install a generator which will power my home from the sounds of all the hoons driving unmufflered motorcycles by my house all day long?

It would certainly reduce my urge to grab my .308 and help the better parts of humanity with more organ donations.

The key is entropy

[pilbender]

There are a lot of engineers here who understand entropy. This can be thought of as the tendency for an event to happen. If there is not enough entropy, that is not enough of a temperature gradient for example, the practical energy will not be available but the theoretical energy could still be high. I would like to know what they could achieve with these low entropy heat sources like the waste heat generated from a computer. If this really could be used, even in small amounts, it would be a major break through. I saw blow torches in those pictures, which to me doesn't represent much of a break through at all. Blow torches produce high heat gradients so lots of things can be done with them to produce useful work.

vibrations

[jovius]

A device turning sound energy into electrical energy is called a microphone.. Piezo-elements cost a few cents, and are widely used as pickups for acoustic instruments. Piezos react to the vibrations of the object they are mechanically attached to.. I wonder if their techology could be used to transform the mechanical vibrations of any object into electrical energy...

But...

[andre_nho]

...isn't the equipment too noisy?

Re:"University" of Utah

[Anonymous Coward]

Neither are bigots.

About the heat-sound-work continuum

[Gen.Anti]

There's been this interesting article about the spectrum of "work", including both heat and sound:

So... Heat is a form of sound?!

Or should I say "heat" is sound, since many educators believe that the word "heat" causes misconceptions. I'll say it this way: thermal energy within physical objects is actually a very loud screech of hypersonic whitenoise. When a hot object is touched to a cold one, "phonons" of sound start pouring between them.

http://amasci.com/miscon/a-rant.html

The upshot: "heat
energy" is the regime where sound has become so high in frequency that it
moves slowly and is renamed as "thermal vibrations."

http://amasci.com/heat.txt

It's basically a Stirling Cycle...

[Anonymous Coward]

These have been around for a while, but they're a pain in the arse to get working well.
It works like a stirling engine.
You have a hot part and a cold part, and you use the expansion and contraction of a fluid to to work.
The idea is that you can drive a resonant chamber by using a thermal difference to create a difference in pressure.
You can either use a standing wave or a travelling one.

You need to ensure that you don't take enough energy out to stop the resonance, which is the biggest problem.

And that's about it.

Here are some links:

http://en.wikipedia.org/wiki/Stirling_engine
http://www.lanl.gov/mst/engine/

The *LONG* Road.....

[IHC Navistar]

Why not convert heat into electricity by using a highly efficient thermocouple, and convert sound waves into electricity by using some kind of pressure-wave transducer?

What's more is that with a thermocouple, you can utilize the cold side as a sort of cooling/refrigeration system.

Man, for wasting $2M, someone should slap the crap out of this idiot and say "Bad scientist! No grants for YOU!"

BTW, is it even practical to convert ambient sound waves into useable amounts of electricity?

Re:Woot

[stonedcat]

Way to screw up an already overly used, ten year old joke from South Park.

Next time you want to be clever, check the source first and try not to fail so badly at life. http://en.wikipedia.org/wiki/Underpants_Gnomes#The _gnomes

Combines with fuel cell?

[eggfoolr]

Considering the recent article on /. about new fuel cell technology. This could be coupled to a fuel cell to turn the waste heat to electricity. Then the only by-product will be H20 (and maybe CO2 depending on the fuel source).

Has potential?

Sound to Electricity you said?

[Anonymous Coward]

Does it do snoring?

I traveled the world and the seven seas. I AM WATCHING YOU THROUGH A CAMERA!

CPU

[darkshadow]

So, when the cpu gets hot enough, the fan comes on. When it has cooled sufficiently, the fan will stop.

I was thinking of this not too long ago

[Anonymous Coward]

Albeit minus the acoustics of it; I was actually only interested in converting heat directly to electricity.

My reasoning, though, was that such a technique could be applied to space shuttles re-entering Earth's atmosphere; the heat tiles currently used are extremely susceptible to damage, and if there is *any* damage whatsoever, the shuttle may catch fire and ultimately crash. By converting the heat being transferred to the shuttle hull into electricity, the astro/cosmonauts on board could run, say, cooling devices to keep the hull even more stable.

Cost of PhD projects

[AlpineR]

Also, as they were built by PhD students, they are probably not very expensive to manufacture.....especially if you were looking at mass-production.

What a strange statement. You do know that PhD students don't pay for their research projects out of their own pockets. The funding comes mainly from grants via the professor. So it's not a matter of what the student can afford, but of how much money the professor can bring in.

For example, my first doctoral project involved building and maintaining a molecular beam epitaxy chamber. That's a meter-diameter, thick metal sphere with a series of chambers attached so that silicon wafers can be loaded and pumped down to a billionth of atmospheric pressure. The central system cost around $250,000. We spent at least another $100,000 on updates and replacements for my project. We eventually abandoned that research, mainly due to the difficulty and cost of safety when handling the extremely poisonous and flammable gases used in epitaxy. I switched to theoretical research which is an incredible bargain, just $3,000 for a new workstation, as long as you have a student with the appropriate intellect for that kind of work.

But even then a PhD research project is not cheap. My professor had to pay about $30,000 a year for my stipend and tuition. Double that to add in overhead and travel. Considering that an experimentalist PhD student might need two years to build one device for their research, that's still at least $100,000 for that first device. I sure hope that mass production isn't going to be done by a Beowulf cluster of PhD students.

AlpineR

Have this....

[thrill12]

...when I put on my steam-generator I produce heat, which in turn enables me to produce a lot of sound by using a kettle, this sound in turn will enable my wind-generator to run on basis of the vibration in the air. Thus I converted heat into sound into electricity.
 
I can do it even more neat: I can turn heat into electricity into sound into electricity into heat into .... - in the end there is not much energy left, but I did it anyway :=)

MOD PARENT UP

[Bugs42]

+1 Most honest post ever seen on /.

The long ARM of the law

[Belacgod]

Analog Rights Management?

Efficiency

[Anonymous Coward]

Symko actually did comment on the question of efficiency, as can be seen in this article:

http://arstechnica.com/news.ars/post/20070605-new- technology-converts-heat-to-electrical-energy-thro ugh-sound.html

It says: "This isn't some crazy perpetual-motion device--Homer Simpson can rest easy, as no laws of thermodynamics are being broken. The prototype demonstrated by Symko can only recover a small percentage of the total energy available from the "waste" heat. Symko says that the efficiency depends on the application and temperature differences: the higher the difference between the source heat and the temperature in the device, the greater the efficiency. He believes that the technology can reach 20 to 25 percent efficiencies and possibly bump solar panel efficiencies from 20 percent (for typical consumer products) to more than 50 percent."