I’ve always been fascinated by the thermocouple and its ability to generate electricity from heat. I’ve often wondered if we could put millions of thermocouples into places where heat is a byproduct of some other operation and capture it as electricity. That may soon happen.
From light.sci-toys.com: In 1821, physicist Thomas Johan Seebeck discovered an interesting effect when he heated a junction of two different metals. He found that they generated an electric current. Actually, he thought it was a magnetic effect, because what he had noticed was that a compass needle was deflected as the current flowed through the wire.
Today, we call the thermoelectric effect he discovered by his name — the Seebeck effect. He must have had a very sensitive compass, because the currents that are generated are very small. Unless the wires are formed into a coil around the compass, to increase the magnetism of the current carrying wire, it would be difficult to notice any movement.
But a modern voltmeter is sensitive enough to show the effect, as shown in the photo. Now that concept has literally taken a quantum leap.
From University of Arizona News – Quantum physicists turn waste heat into power
University of Arizona physicists have discovered a new way of harvesting waste heat and turning it into electrical power. Taking advantage of quantum effects, the technology holds great promise for making cars, power plants, factories and solar panels more efficient.
What do a car engine, a power plant, a factory and a solar panel have in common? They all generate heat – a lot of which is wasted.
University of Arizona physicists have discovered a new way of harvesting waste heat and turning it into electrical power.
Using a theoretical model of a so-called molecular thermoelectric device, the technology holds great promise for making cars, power plants, factories and solar panels more efficient, to name a few possible applications. In addition, more efficient thermoelectric materials would make ozone-depleting chlorofluorocarbons, or CFCs, obsolete.
The research group led by Charles Stafford, associate professor of physics, published its findings in the September issue of the scientific journal, ACS Nano.
“Thermoelectricity makes it possible to cleanly convert heat directly into electrical energy in a device with no moving parts,” said lead author Justin Bergfield, a doctoral candidate in the UA College of Optical Sciences.
“Our colleagues in the field tell us they are pretty confident that the devices we have designed on the computer can be built with the characteristics that we see in our simulations.”
“We anticipate the thermoelectric voltage using our design to be about 100 times larger than what others have achieved in the lab,” Stafford added.
Catching the energy lost through waste heat has been on the wish list of engineers for a long time but, so far, a concept for replacing existing devices that is both more efficient and economically competitive has been lacking.
Unlike existing heat-conversion devices such as refrigerators and steam turbines, the devices of Bergfield and Stafford require no mechanics and no ozone-depleting chemicals. Instead, a rubber-like polymer sandwiched between two metals acting as electrodes can do the trick.
Car or factory exhaust pipes could be coated with the material, less than 1 millionth of an inch thick, to harvest energy otherwise lost as heat and generate electricity.
The physicists take advantage of the laws of quantum physics, a realm not typically tapped into when engineering power-generating technology. To the uninitiated, the laws of quantum physics appear to fly in the face of how things are “supposed” to behave.
The key to the technology lies in a quantum law physicists call wave-particle duality: Tiny objects such as electrons can behave either as a wave or as a particle.
“In a sense, an electron is like a red sports car,” Bergfield said. “The sports car is both a car and it’s red, just as the electron is both a particle and a wave. The two are properties of the same thing. Electrons are just less obvious to us than sports cars.”
Bergfield and Stafford discovered the potential for converting heat into electricity when they studied polyphenyl ethers, molecules that spontaneously aggregate into polymers, long chains of repeating units. The backbone of each polyphenyl ether molecule consists of a chain of benzene rings, which in turn are built from carbon atoms. The chain link structure of each molecule acts as a “molecular wire” through which electrons can travel.
“We had both worked with these molecules before and thought about using them for a thermoelectric device,” Bergfield said, “but we hadn’t really found anything special about them until Michelle Solis, an undergrad who worked on independent study in the lab, discovered that, low and behold, these things had a special feature.”
Using computer simulations, Bergfield then “grew” a forest of molecules sandwiched between two electrodes and exposed the array to a simulated heat source.
“As you increase the number of benzene rings in each molecule, you increase the power generated,” Bergfield said.
The secret to the molecules’ capability to turn heat into power lies in their structure: Like water reaching a fork in a river, the flow of electrons along the molecule is split in two once it encounters a benzene ring, with one flow of electrons following along each arm of the ring.
Bergfield designed the benzene ring circuit in such a way that in one path the electron is forced to travel a longer distance around the ring than the other. This causes the two electron waves to be out of phase once they reunite upon reaching the far side of the benzene ring. When the waves meet, they cancel each other out in a process known as quantum interference. When a temperature difference is placed across the circuit, this interruption in the flow of electric charge leads to the buildup of an electric potential – voltage – between the two electrodes.
Wave interference is a concept exploited by noise-cancelling headphones: Incoming sound waves are met with counter waves generated by the device, wiping out the offending noise.
“We are the first to harness the wave nature of the electron and develop a concept to turn it into usable energy,” Stafford said.
Analogous to solid state versus spinning hard drive type computer memory, the UA-designed thermoelectric devices require no moving parts. By design, they are self-contained, easier to manufacture and easier to maintain compared to currently available technology.
“You could just take a pair of metal electrodes and paint them with a single layer of these molecules,” Bergfield said. “That would give you a little sandwich that would act as your thermoelectric device. With a solid-state device you don’t need cooling agents, you don’t need liquid nitrogen shipments, and you don’t need to do a lot of maintenance.”
“You could say, instead of Freon gas, we use electron gas,” Stafford added.
“The effects we see are not unique to the molecules we used in our simulation,” Bergfield said. “Any quantum-scale device where you have a cancellation of electric charge will do the trick, as long as there is a temperature difference. The greater the temperature difference, the more power you can generate.”
Molecular thermoelectric devices could help solve an issue currently plaguing photovoltaic cells harvesting energy from sunlight.
“Solar panels get very hot and their efficiency goes down,” Stafford said. “You could harvest some of that heat and use it to generate additional electricity while simultaneously cooling the panel and making its own photovoltaic process more efficient.”
“With a very efficient thermoelectric device based on our design, you could power about 200 100-Watt light bulbs using the waste heat of an automobile,” he said. “Put another way, one could increase the car’s efficiency by well over 25 percent, which would be ideal for a hybrid since it already uses an electrical motor.”
So, next time you watch a red sports car zip by, think of the hidden power of the electron and how much more efficient that sports car could be with a thermoelectric device wrapped around its exhaust pipe.
Reference: Giant Thermoelectric Effect from Transmission Supernodes. Justin Bergfield, Michelle Solis, and Charles Stafford. ACS Nano Sept. 2010.
Whoa, this is a computer simulation. They haven’t actually built this device!
In other words, it is a Computer Model! While I hope they have success, we know how reliable computer simulations are.
REPLY: Think of it like Autocad for molecular structures – Anthony
Nice. Could we power all of The Goreacle’s mansions from his own hot air?
“I’ve often wondered if we could put millions of thermocouples into places where heat is a byproduct of some other operation and capture it as electricity. That may soon happen.”
Has happened.
I was looking into this a while ago to use the waste heat from some computers to drive plenum fans to remove the heat from where my commuters are running and distribute it into the rest of the house during the winter (they have AC in their room for the summer)
I heat the house with an electronically controlled very high efficiency recycled wood pellet stove (www.harmanstoves.com). So I also looked into using the TEG to provide the 3 amps it takes to run the pellet stove exhaust blower, heat distribution blower, auger motor and electronics, but the cost for 400 watts was a bit much. If the price comes down, I’m in.
http://www.tegpower.com/products.html
“Universal TEG Battery Charger
Model: UTEGEC
Retail Price: $139.99
Shipping: $9.00
Delivery Time: 1 to 2 weeks.”
“Wood stove TEGs are no longer available for purchase directly from this website, however you can purchase them locally.”
Note: I am not affiliated with these company in any way.
I suspect some of the claimed theoretical efficiency will be lost in translation from computer design to hardware reality, but it sounds good anyway.
I’ve been using 4 peltier cpu cooling units (3.5 oz) to recharge small batteries on winter backpacking trips by putting them over my home made titanium woodstove (3 oz) and sitting a pan of cold water on top to cool the opposite sides.
That is just awesome.
See what happens when the power of science is utilised for GOOD, as opposed to EVIL?
Andrew 30, how far do your commuters run, and where are they running to?
I always found that putting commuters on a hampster wheel was most unsatisfactory, as the commuters went around in circles, and didn’t actually go anywhere, and thus became disenchanted – not to mention not being “commuters” any more, because they did not in fact commute anywhere.
Have you solved the secret, and harnessed the power of your commuters on a distance-running treadmill? I am impressed that you thought to aircondition their room in summer, but surely this uses more energy than can be generated?
The only question I would ask about that technology is how you create a ‘wire’ if the benzene ring side chains in the wire backbone are at positions 1 and 3 – it’d take some pretty controlled steric reactions to make it straight……….
But a really fascinating article, nonetheless……………
I believe the Russians use TEG’s to operate gas pipeline valves in remote locations. They use some of the gas from the pipeline to generate the heat required for the Thermo Electric Generators. Not very efficient but a lot cheaper than running power cables to out of the way places. It’s specialist applications in specific situations like that where the technology is currently viable.
Nice stuff. Not built yet, though. Let’s see what real problems come up when they try to fabricate it, and then fabricate it economically.
I also find this comment a little worrying: “With a very efficient thermoelectric device based on our design…” They may mean that their design is already very efficient. But it’s easy to read as weasel words.
“Using the waste heat from an automobile they could power an electric lightbulb.”
Waste heat from automobile has got to be around 10kw …. provides 100W of energy. Wow! This is going to change the world! (Not)
It’s an old idea, my grandfather had a thermo thingy which was heated on the stove producing electrical current to run the wireless.
Umm…. if convertible into actual technology, this could be very good news.
But I’m a bit suspicious about anything that is only done ‘in theory’. Theories are only any good when verified by experiment..or in this case building the b…y thing.
I’m also a bit suspicious of their explanation of getting the electrons to go two different ways around a benzene ring…years ago the accepted concept was that the symmetrical and joined structure of benzene encouraged ‘resonance’ in the electron wave…whereby they were all simultaneously spread across the whole molecule. With this (admittedly primitive) concept, there is no possibility for electrons to go one way or another. Maybe the ideas have moved on…quantum mechanics is notoriously difficult to explain using model sbaed on everyday experience. But that one doesn’t ‘feel’ right to me.
So overall a slightly qualified welcome so far… great that it was an undergraduate who discovered the effect. Just shows that it is not only the trained and tenured professionals that can do real science. Any ‘resonances’ to any other fields there?
marcus25 says: (September 29, 2010 at 12:54 am) It’s an old idea, my grandfather had a thermo thingy which was heated on the stove producing electrical current to run the wireless.
Would really like to hear more on that, Marcus.
From the story: …the devices of Bergfield and Stafford require no mechanics and no ozone-depleting chemicals.
Think they could have managed to at least hint there would be less, or a net loss of, CO2 as well…
Roger Carr
probably worked on the same principle as these
http://www.epower4.com/cplanguages.htm
From reading “The Field” and thinking about all the brilliant scientists this book writes about, I have the strong impression that the aspect of Quantum
MechanicsPhysics called the “Zero Point Field” has huge potential for exploration, to help our energy requirements as well as other things – but is still seen as off-topic or “flat-earthist” by those guarding conventional science.What I love here is the delight in new ideas and lots of views, and the humanity of courtesy, all of which creates such a fertile environment for exploration – unlike the paradigm of cutthroat / paywalls / non-debate / alarmism / obfuscating elitism / power-grabbing politicization / that’s come to a head with the IPCC, Mann’s hockey stick, and Climate Science generally, which will surely slowly throttle itself.
Thanks for another interesting lead.
Nice, but I want a generator to tap into ZPF. And modify gravity as well.
So
ps: The Pioneer and Voyager probes are still working!!
Sorry mods. accidental posting.
What I mean is:
So I can have a trip with the Milleneum Falcon to the stars, and the toilet working the right way…. 🙂
This is new? Thirty years ago I was humping bloody great propane cylinders up mountains to power thermal generators for battery chargers to run navigation beacons. Does time run more slowly in Arizona?
@Ross Jackson says:
September 28, 2010 at 11:25 pm
Whoa, this is a computer simulation. They haven’t actually built this device!
In other words, it is a Computer Model! While I hope they have success, we know how reliable computer simulations are.
—————————
These scientists aren’t trying to change government policy based on their computer models though. Nor are they claiming that this proves anyhting.
They have created a computer simulation to see if the theory has any merit and will then see if it works in practice.
Marcus — thanks for the URL to the TEG 5000 — Thermo Electric Generator
Hope they go from theory to lab device to prototype then to large scale manufacturing without too many issues. One issue is how rusting can be accelerated when disparate metals contact each other. It’s long road, so to speak.
Until they grasp the simple fact that particles are purely tangential points on waves, they will continue saying they are both particles and waves, whilst wondering why they are making such slow progress.
The nature of the particle depends upon the perspective relative to the universe and its frequency. The universe consists not of matter or missing matter or dark energy but information transmitted in waves and simply defined by a system of interlock co-ordinates.
Dont ask for a link, I am trying to develop the theory into a working model (snip) sorry about the rude word, emm a working hypothesis
Ferric patella!
@Kaboom, before you poke fun at someone else’s typos (although your gags were funny), be sure you’re spelling hamster correctly.
Bit silly giving the game away when it has not been built yet.
I hope they have comprehensive patents on it……
Thermocouples is also one way electrical power is generated by an Atomic Battery for use in space probes.
Lucy Skywalker says:
September 29, 2010 at 1:59 am
I have the strong impression that the aspect of Quantum Mechanics Physics called the “Zero Point Field” has huge potential for exploration
Yes, it is quite intriguing. If one could devise a valve, like the ones used for getting energy out of the waves, but this time out of the zeropoint energy sea we would be all set.
200 100-watt light bulbs is 27 horsepower. Seems a bit excessive for just the exhaust pipe alone if all the watts of heat energy were converted to electrical energy (100% efficient, which is impossible) unless we’re talking about a 500hp motor with the gas pedal to the floor. In normal driving conditions the motor is seldom producing anywhere near its rated horsepower. Diesel engines are about 40% efficient. A modest weight mid-size passenger car cruising at 55mph is using about 25hp at the wheels which means about 37hp of waste heat. Much of that waste heat leaves through the water jacket/radiator not the exhaust pipe.
Conventional thermopile efficiency is in the low single digits and temperature differentials of a thousand degrees F are needed to reach even that low efficiency and the voltage is in millivolts requiring many of them in series to attain usable voltages.
If someone here who has access to ACS Nano paper (behind a paywall) could get some specifics in regard to voltage, temperature, and efficiency that would be cool but I’m pretty sure the talk of getting a usable amount of electricity from the waste heat in a motor vehicle engine is pie-in-the-sky.
Is this not using CO2?
Heat and CO2 two different processes…whoda thunk?
Is this not the same excuse used by global warming for greenhouse gas effect?
Hate the use of the word quantum for molecules that vibrate when heated.
Mike Haseler says:
September 29, 2010 at 12:32 am
“Using the waste heat from an automobile they could power an electric lightbulb.”
Waste heat from automobile has got to be around 10kw …. provides 100W of energy. Wow! This is going to change the world! (Not)
Worth another read Mr Haseler. It actually says 200 X 100Watts. If your estimate for automobile waste heat is correct (I suspect not) then they can generate 20KW from 10KW – which I would call world changing.
One thing you have to get right on this site is your estimate of Watts.
I believe Whirlpool Corporation built and tested a residential natural gas furnace with a thermoelectric-powered circulating fan in the 1960s. The factory standard cost of the TE system was quite high; and, the heat extracted by the thermocouples on the walls of the combustion chambers tended to “chill” the combustion reaction, increasing carbon monoxide concentrations to unacceptable levels. Also, to avoid condensation in the flue, the exhaust gas temperature remained unchanged; and, thus, the overall efficiency of the furnace did not increase.
Perhaps this new TE technology will become available just as we are ending the burning of fossil fuels to help keep Jim Hansen out of jail.
“Roof Shingles! Yep! That’s the future boy. Shingles!” said the rich old man to the brand new Graduate.
Then Mrs. Robinson said, …
As this appears to be a boundary effect, designing such systems to have huge regions of interface and being able to collect the power is probably going to be technically difficult. Good luck. This will not be soon coming to stores near us. Of course, the gov’t could mandate the not-ready-for-prime-time technology into cars and make cars too expensive to buy.
There is an interesting potential application of this technology being discussed here
http://focusfusion.org/index.php/forums/viewthread/684/
I woudnt bet any money on it. Remember the super capacitor (Eestor). http://www.eestor.us/ just a web page under construction for 3 years.
Remember Lonnie Johnson the super soaker inventor (Johnson Electromechanical System) http://www.johnsonems.com/ and the JTEC (Johnson Thermoelectric converter. I’m sure there are more that other WUWT readers will remember.
Mick says “ps: The Pioneer and Voyager probes are still working!!”
An excellent point. Thermoelectric generators using a Plutonium thermal source (no CFC’s, no CO2) have been in service for several decades now.
My family’s world book encyclopedia from the mid-1960’s had a Science Fair project describing the construction of a Seebeck effect thermoelectric generator based on multiple junctions of dissimilar metal wires. Modern Thermoelectric modules are also based on ‘Quantum’ effects’ and ‘electron properties’.
I do think this is an interesting avenue of basic research with a 10 – 25 year horizon.
The usual engineering issues will of course show up when trying to reduce this to working prototypes. Bringing heat to one side of the film, and extracting it from the other, to maintain a sufficiently high delta T (without melting or decomposing what will likely be a waxy organic film, like what is created using Langmuir-Blodgett monolayer deposition techniques) and therefore generate useful amounts of power, while minimizing the thermal conductivity and maximizing the electrical conductivity of the film itself, will be challenging. I’d be interested to see if they estimated the thermoelectric figure of merit for this theoretical material.
Grey Lensman says:
September 29, 2010 at 3:29 am
You an E E Doc Smith fan?
I wonder about the benzene rings under high heat. Won’t they burn up?
Wasn’t there some work being done on infrared solar cells, using nano scale antennas? I believe that they were having trouble converting the energy that was being trapped into useable electricity, something to do with it’s frequency, of the order of billions of Hz i.e. GHz – Don’t suppose anyone knows anything more about this?
This gives a great example of the current state of TEGs and use in Vehicles.
http://www.i-sis.org.uk/harvestingWasteHeat.php
I have also seen a figure of 1Kw generated by the heat from a Truck engine.
Anthony did you know that a 4″ parabolic reflector from an electric Torch can generate a heat of 350-450 degrees C at it’s focal point using UK sunshine. It should be much higher in the Desert.
Hummmm…..Just a thought or two.
“The greater the temperature difference, the more power you can generate”
But, the distance between Th and Tc is the thickness of the polymer coating: “…less 1 millionth of an inch thick”.
As the distance between Th and Tc approaches “0”, the temperature difference between Th or Tc must also approach “0”. (Unless the polymer has magic heat insulating properties. They didn’t mention the inclusion of magic pixie dust.)
This is an interesting theoretical concept. And, it might actually work in practice. And it could possibly create useful amounts of power. And if it all works out, it could be the foundation of an economically rational product. (E.g. If the cost of getting electricity to your home is greater than $30 or $40 K, a full blown solar power system becomes economically rational. Otherwise, it probably isn’t. Depends on what your definition of “is” is. Perhaps: “Is” is what “isn’t” isn’t?)
But, as is often the case, if it were a “slam dunk”, then really really smart people would fund the project so that they would make all of the “profits”. If they are asking Big Brother to fund it with Other People’s Money (OPM), then it is suspect. (E.g. Cold Fusion).
Down here in the Free Republic of Texas a local good ole boy, T Boone Pickens, was proposing a wind farm project that would cover some 1,200 square miles of the Texas Panhandle. But first, he wanted the state to use OPM to pay for the transmission system. Now, just by coincidence, the legislature passed a law so that power transmission right of ways can be used for things like water pipelines. And, it just so happens, that at one end of the proposed right of way water was cheap and at the other end water was expensive.
Now you can ask yourself, “Self, that T Boone is a pretty smart feller. Why would ole T Boon put his own money in a project that will only exist as long as Big Brother subsidizes it with OPM? As soon as the subsidies run out, your investment will be worthless.”
Let me know what “Self” says back to you.
Also…..
The paper mentions “ozone-depleting chlorofluorocarbons, or CFCs” several times. I thought that theory was pretty much proven to be another hoax, a la “hockey stick”. The repeated inclusion in this paper just increases the cause for suspicion.
Regards,
Steamboat Jack (Jon Jewett’s evil twin)
A.C.OSBORN
Yes but I am a human being.
Could one run this system in reverse, applying a voltage to cool one of the plates with respect to the other?
I hate it when reporters say N football fields or 200 X 100W. Just say 20KW.
A small ICE producing 10KW will propel a small car on the highway. I does produce 20KW+ of waste heat. But most of it is low quality, not the high temp of exhaust. All heat engines become less efficient with small heat difference, I expect thermocouples have a max theoretical efficiency too. I doubt thermocouples on the exhaust can produce more that a few KW electricity.
Roger Carr says:
September 29, 2010 at 2:48 am (Edit)
Marcus — thanks for the URL to the TEG 5000 — Thermo Electric Generator
From that link:
“This generator has the capacity to power the average U.S. home.”
Bullcrap. There is no way that unit will produce enough electrical energy from burning gas to power the average U.S. home.
In Norway, some university research teams have been trying to make an efficient TEG. The best they can manage so far is to run a small portable tv off a unit which covers the top of a woodburner.
I’m just curious if someone could compare a couple of numbers for me? Those are the waste heat from a running car engine, figuring it is only running, say, 30 minutes a day (going 25 miles or so to work and back) and the heat generated inside a car sitting in direct sunlight in a parking lot for the 8 hours the car is parked at work.
It strikes me that if the process were efficient enough and the solar heat generated was high enough, that an electric car could someday be recharging as it sat in the sun, but I don’t have a feel for the comparative energy levels involved (engine waste heat vs. solar heat inside the car.)
Can someone reading this run the numbers? Thanks.
Rod
DirkH says:
September 29, 2010 at 7:36 am (Edit)
Could one run this system in reverse, applying a voltage to cool one of the plates with respect to the other?
Yes, that’s the Peltier effect as opposed to the Seebeck effect. You can use them to cool cpu s. There are a million and one mini fridges on ebay using the same principle.
So the space probes are still working; that’s wonderful.
I think I have said several times here at WUWT, that using “electricity” to create “heat” should be a felony. And that is often as close to 100% conversion as you might ever expect to get. But you are starting off with “real” energy; ordered energy as from a battery, or the gravity driven weight on a cuckoo clock; and you are turning it into crap; waste disordered energy of a mechanical nature that we call “heat”. It’s that wastefullness that I decry; even though it is convenient.
If you try to go in the reverse direction; from heat to energy; that too should be a felony; called “stupidity”. You are trying to use the disordered chaos of random molecular mechanical energy of particles rushing in all directions, to try and get some useful work done; and there is no way to can ever recover 100% of the total energy that is represented by that heat. Even an Australian sheep dog could never organise all those molecules to get moving in the same direction to accomplish something useful.
So even though you can convert some fraction of the “heat” energy into useful work; or what is equivalent; the capacity to do useful work, which is ENERGY (real) you have to deal with things like Entropy, and the Carnot Efficiency limits and such.
So it is a stupid thing to do; even though there are applications(such as those marvellous space probes) where it is one of the very few options you have.
Thermopiles (bolometers) can be good detectors of “heat”, in that they can detect through their heating, radiations over a very large range of wavelengths; but they still are quite low efficiency.
One of the first things you learn in thermodynamics is that you can never convert 100% of the “heat” in a system into useful work or the equivalent which would be for example, electricity.
Those space probes are an ingenious application of a rather inefficient process; but one of the few possibilities for providing ANY electricity way the blazes out in free space; where free clean green renewable energy from the thermonuclear fusion of stars, is too sparse to be useful.
So everybody should go out and buy a thermopile gizmo from Edmunds Scientific or your local equivalent; and start off with something simple; like trying to run your electric toothbrush or your Ipod/pad/pud/ped/pid off it, so you will learn something about thermodynamics.
So yes going either way from electricity to heat or back is stupid, and should be a felony; unless you are building a space probe.
There is a relation among all of these phenomena:
http://www.scribd.com/doc/38251461/Unified-Field
Very old basic science. Old technology with a computer model strapped on. Interesting, but too similar to all the other pie-in-the-sky energy sources: lots and lots of “free” energy, very expensive hardware required, and lots of it, net result: very little net usable power at very high cost. We may have nuclear fusion before this research yields anything useful. I’d spend my bucks on nuclear fusion research.
A weirder idea? for alternative energies (O My!, is it out there anything different than energy?). Well, let’s say it:
-Get a generator, then fix a pulley on the end, wind a long, long string or rope around it,
then, tie a balloon at the end and let it pull the rope/string up: It will make the generator move, producing electricity.
What did it happen? We have extracted energy from Gravity, as the balloon opposed Gravity, by flying up, up and away !
Can this idea be funded by Cap&Trade? 🙂
That table of Seebeck coefficients is nice to have; especially if one is doing highly sensitive DC measurements and wants to keep thermal EMFs at a minimum.
The Bismuth / Anti-money combination is one of the more common junctions used for thermo-electric generators.
About all that one can say about Bismuth, is that it is a very poor excuse for a metal.
I recommend that you stay away from the Tellurium though. I don’t care if I die, before I ever get a look at a piece of Tellurium.
We used to use about 5 ppm or thereabouts of diethyl Telluride in Hydrogen for N Type doping of Gallium Arsenide, and Gallium Arsenide Phosphide Epi layers for Red LEDs. Easily wins my vote as THE most obnoxious odor in the Universe.
“Like water reaching a fork in a river, the flow of electrons along the molecule is split in two once it encounters a benzene ring, with one flow of electrons following along each arm of the ring.”
I hope this awful analogy is from the article writer and not the researchers. It would have water flowing uphill!
Quite a few attempts have recently been made to recover exhaust heat energy from vehicle engines.
BMW has another concept to recover waste heat from the exhaust http://www.gizmag.com/go/4936/.
In this concept the exhaust is routed to a heat exchanger to create steam and drive a small steam engine. The steam engine is coupled to the transmission. Supposed to reduce fuel consumption by about 10-15%, but only when the car is mainly used for long distance driving.
The working fluid is an alcohol/water mix and runs closed loop with a condensor mounted up front.
Of course, any competent mechanic can easily bybass the steam engine and convert that car into a mobile moonshine still. Seems like a concept NASCAR would love.
Another way to recover the waste heat from an internal combustion engine that I find interresting is the 6-stroke Crower engine:
http://en.wikipedia.org/wiki/Crower_six_stroke
In this engine, instead of exhausting the burned gas directly out the exhaust pipe, it is recompressed (5th stroke) and at the end of that compression cycle water is injected directly into the combustion chamber. This water flashes into steam and allows the engine to produce another (6th stroke) power cycle before the (then relatively cold) mixed gas is exhausted.
Of course the problem there is that it requires a water tank or large condensor, and the remaining exhaust heat is too low to operate a catalytic converter.
Eric Gisin says:
September 29, 2010 at 7:55 am
I hate it when reporters say N football fields or 200 X 100W. Just say 20KW.
A small ICE producing 10KW will propel a small car on the highway. I does produce 20KW+ of waste heat. But most of it is low quality, not the high temp of exhaust. All heat engines become less efficient with small heat difference, I expect thermocouples have a max theoretical efficiency too. I doubt thermocouples on the exhaust can produce more that a few KW electricity.
You may well be correct, but at the moment we use Mechanicly driven Alternators to do the same thing and they sap energy from the engine that could be going to the wheels.
So if it is free energy and can replace the Alternator I disagree with
George E. Smith says:
September 29, 2010 at 8:03 am
Not only could this reduce waste, it could also eliminate the need for nuclear plants to build cooling towers. That would make them more competitive.
Could it maybe drain excess heat from computer chips?
As a chemist, I’d predict that those molecules will lie flat on the bottom electrode surface, to maximize contact. That would be the most stable configuration of a polymeric molecule.
I can’t see how they’d get a “forest” of those molecules standing up like that. People make electrodes covered with a “lawn” of molecules, but typically the way it’s done is to make the molecule linearly asymmetric.
One terminus of the molecule is made to have far more affinity for the electrode than the rest of the molecule. So, the low-energy position is to stand on end. I don’t see any modification of the molecular terminus to achieve that status in the picture, but maybe they’ve simplified it for publication.
I can also see how the current might bifurcate around the molecular rings. But notice that the longer path will also be higher resistance. So, the amplitude of current is unlikely to be bilaterally symmetric around the ring. That means the phase cancellation won’t be complete. Presuming the device works as advertised, the incomplete cancellation may impact the available energy.
As usual, the engineering study will tell the tale.
Only ONE way to handle this announcement:
http://www.solargeneral.com/humor/bs-meter.gif
Please note the position on this HIGHLY SCIENTIFIC DEVICE!
Enneagram says:
September 29, 2010 at 9:29 am
A weirder idea?
Not at all. Solar energy vs earth gravity.
At night balloon will cool down (pV=nRT), loose volume and drop down a bit (so you can use some of the energy stored while was going up) to partially wind it back, next day sunshine will worm it up, increasing the volume, and balloon goes up again. Lots of free energy!
Steamboat Jack says:
September 29, 2010 at 7:12 am
“But, the distance between Th and Tc is the thickness of the polymer coating: “…less 1 millionth of an inch thick”.
Yeah. If they think it’ll work on an exhaust pipe those aren’t very hot either for a useful thermopile. I’m presuming you spray it on metal and need the usual radiator fins. I’d sure love to see the performance curves they think they’re going to get. Something 20% efficient at say 160F that was much cheaper to produce than solar cells would be a bit earth shaking. 160 is easy to get with solar. Just heat water in an insulated tank to that temperature and draw it off through the thermopile as needed. You could use a propane or natural gas fired water heater as a backup or to top off the temperature if the sun wasn’t doing it. Hell even 10% efficient and same price as a solar cell would be awesome as you can’t power a solar cell from stored hot water. That alone would make it hugely attractive since it makes energy storage inexpensive, long lived, and almost maintenance free.
Dave Springer- “Something 20% efficient at say 160F that was much cheaper to produce than solar cells would be a bit earth shaking.”
The Thermoelectric efficiency is ultimately limited by the Carnot efficiency, which is eff = T(hot) – T(cold))/T(hot), all in degrees Kelvin. This is the limit for an infinite Thermoelectric figure of merit. Assuming T(cold) = 273 K, and T(hot) = 160 F = 345 K, the best you can do is 21%. So as you say, it would be earth-shaking indeed.
“”” A C Osborn says:
September 29, 2010 at 10:08 am
Eric Gisin says:
September 29, 2010 at 7:55 am
I hate it when reporters say N football fields or 200 X 100W. Just say 20KW.
A small ICE producing 10KW will propel a small car on the highway. I does produce 20KW+ of waste heat. But most of it is low quality, not the high temp of exhaust. All heat engines become less efficient with small heat difference, I expect thermocouples have a max theoretical efficiency too. I doubt thermocouples on the exhaust can produce more that a few KW electricity.
You may well be correct, but at the moment we use Mechanically driven Alternators to do the same thing and they sap energy from the engine that could be going to the wheels.
So if it is free energy and can replace the Alternator I disagree with
George E. Smith says:
September 29, 2010 at 8:03 am “””
Well in a well designed alternator, the input energy is “real” ordered mechanical energy; the exact same sort of energy that is getting the car along the road. Very little of that energy is wasted as mechanical friction losses in the bearings, and belt drive; although they don’t exactly bend over backwards to get it to absolute minimum.
And the conversion into electric energy (from mechanical) is also very efficient. Well for practical reasons to keep the thing small, they tend to run the copper wire at a relatively high temperature; just to keep the amount of copper required at a minimum. And for the same reason; they run the magnetic flux density in the magnets at a fairly high level to reduce the amount of good magnetic steel or other alloy. So they typically run the total mechanical to electrical energy exchange efficiency at some compromise level that keep the size and cost down; but inherently the conversion from mechanical to electrical is almost 100%. It is in the extraction of the electricity from the alternator, that one incurs losses due to electrical resistance, and magnetic hysteresis and eddy current losses.
So good luck on getting your thermo-electric converter to even approach the efficiency of an automobile alternator efficiency; I’ll stick with what has been proven to work; but if thermo converters eventually take over; I’ll switch. I would rather spend the research effort trying to improve the efficiency of the car’s engine; so it didn’t make so much waste heat in the first place.
And remember that those polluting internal combustion greenhouse pollution producing engines are going to be replaced by free clean green renewable electric cars anyway; so there isn’t going to be any hot exhaust pipe to scrape thermo electricity from.
But I’m always happy to have people disagree with me; that way if they get richer than me; they can take over paying some of the taxes I have to pay; because my employer wants to keep me working.
I liked the references to Freon and CFCs. Don’t they know that these materials have been phased-out as refrigerants already, and that a 2nd generation of replacements will be introduced in the next 3-5 years that essentially have no ozone-depleting effects or greenhouse effects either (first generation replacements were HCFCs and HFCs).
Metryq says: September 29, 2010 at 4:20 am
“@Kaboom, before you poke fun at someone else’s typos (although your gags were funny”
No offence taken, and it was funny.
I’ve done worse.
Try leaving the ‘l’ out of public when the context is “there should be more public access at the meetings”. Spell checks ok, but…
“With a very efficient thermoelectric device based on our design, you could power about 200 100-Watt light bulbs using the waste heat of an automobile,” he said. “Put another way, one could increase the car’s efficiency by well over 25 percent, which would be ideal for a hybrid since it already uses an electrical motor.”
I am surprised that nobody has yet commented that the above claim is complete and utter nonsense. It violates the laws of thermodynamics and is simply a 21st century version of that age-old chestnut: the perpetual motion machine.
To the extent that the thermopile generates electricity, it derives that energy from the car’s fuel and in so doing it make the internal combustion engine proportionately less efficient, thereby reducing its power output. This is essentially a zero-sum game with no efficiency benefit whatsoever. (And in practice there would actually be an efficiency loss due to having to convert the electricity generated back into motive power.)
Daft or what?
Wow, this is a bit of a game-changer, isn’t it. Makes it obvious what a nonsense subsidies for PV panels are. Looks like the best way to generate electricity from the sun will be to bury a field full of pipes, run water through them, and use the new tech to generate electricity from the temperature difference. Ground source heating -> electricity is a win, particularly considering it can be installed on agricultural land deep enough that it won’t interfere with agriculture – no land cost.
As Steamboat Jack has said “The greater the temperature difference, the more power you can generate.
But, the distance between Th and Tc is the thickness of the polymer coating: “…less 1 millionth of an inch thick”.
Yes, the driving force for any thermocouple is the delta T between the hot and cold junctions, so even thermocouples have to obey the Second law of Thermodynamics. It is implied from the way this article is written we can just directly convert any heat that is lying around into electricity, not true. So the skeptic in me wonders how they intend to maintain a heat difference between junctions that are angstoms apart.
Vuk etc. says:
September 29, 2010 at 10:33 am
Ho,Ho!, just don’t say it aloud!, that would work as a hanging up machine too 🙂
Pat Frank says:
September 29, 2010 at 10:19 am
As a chemist, I’d predict that those molecules will lie flat on the bottom electrode surface, to maximize contact. That would be the most stable configuration of a polymeric molecule.
Pat, I don’t know. I’m just speculating. But maybe there’s an entropic driving force for a forest. And from the viewpoint of enthalpy, maybe you get more of an advantage by sorbing many more molecules on end, in the sense of each absorption being stronger than an equivalent number of surface interactions from fewer molecules lying flat. A multiply-sorbed molecule has “less to give”.
Rhys Jaggar says:
September 29, 2010 at 12:09 am
The only question I would ask about that technology is how you create a ‘wire’ if the benzene ring side chains in the wire backbone are at positions 1 and 3
Rhys – There is an electronic preference for the (using your numbering scheme) 1 and 4 positions when the polyphenyl ether is formed, due to differences in electron density (and assuming the substitution is electrophilic). So, we don’t have to worry about the 3-position. I’m sure there is some chemical trick to getting consistent substitution at the 1-position. But I can’t tell you what that is, unless it’s a surface-catalyzed reaction that convinces the ring to lie on its side with the oxygen sticking away from the surface, leaving the 1-position accessible, but blocking the 4-position.
oeman50 says:
September 29, 2010 at 12:28 pm
Yes, the driving force for any thermocouple is the delta T between the hot and cold junctions, so even thermocouples have to obey the Second law of Thermodynamics. It is implied from the way this article is written we can just directly convert any heat that is lying around into electricity, not true.
I don’t understand. Are we talking about two different processes here? Look at the picture at the beginning of the article where a candle is directly heating the junction between two metals and is creating a voltage difference. That doesn’t seem to hinge on “the delta T between the hot and cold junctions.” Is the Seebeck Effect different from a thermocouple? Can someone clarify?
“”” David Socrates says:
September 29, 2010 at 11:38 am
“With a very efficient thermoelectric device based on our design, you could power about 200 100-Watt light bulbs using the waste heat of an automobile,” he said. “Put another way, one could increase the car’s efficiency by well over 25 percent, which would be ideal for a hybrid since it already uses an electrical motor.”
I am surprised that nobody has yet commented that the above claim is complete and utter nonsense. “””
Well David; you haven’t been reading very closely. Several people have commneted on the p[racticality of this scheme.
Actuallt it doesn’t have to violate the second Law; well of course it can’t so that is a non issue. But the second Law does place some restrictions on the amount of electricity one might recover from the waste heat.
It’s a bit like running a stable with a lot of horses that you feed hay to. The result is you end up with a lot of HS which is the Equine equivalent of BS.
So this thermo-electric scheme lets you burn the HS, for waste heat which you use to run your TE plant.
Well if you wanted to improve the efficiency of this stable; figuring out how to use up the HS effluent is not the answer.
It would be better to breed a better kind of horse that uses the pristine hay more efficiently and doesn’t excrete as much HS. Or you could mix the hay that has already been once through the horse, in with the hay or oats and recycle it. Of course that kind of Hay comes quite a bit cheaper; but better to rerun it to create extra horse power than to just burn it.
Using up waste heat is old hat. Most of you are too young to remeber the North American Mustang (aptly named); otherwise known as the P-51 WW-II fighter. It had this weird radiator power bulge sticking out under its belly so that when it was engaged in strafing ground targets; the bullets could kick up stones off the road, to punch holes in the radiator.
Everybody thinks the P-51 radiator was a nifty design because when the air rushed through it and out the back, it was heated by the radiator cooling fluid, and that expanded the gas, and raised the exhaust velocity and momentum to give a slight jet engine thrust to the plane from that waste heat. This is often touted as one of the superior design features of the P-51.
Actually, it was a ho-hum thing. You see back in 1935 when Supermarine was developing the prototype for Reginald Mitchell’s Spitfire fighter, a chap by the name of Meredith who worked for the British Royal Aircraft establishment figured out the theory of such a radiator design; in fact is has become known to history as The Meredith Radiator.
Properly implemented the conversion of waste heat from the cooling fluid, into extra thrust, is so efficient that the generated thrust exceeds the aerodynamic drag caused by the crossection of the radiator and its housing.
And that very successful Meredith Radiator was implemented on K 5054 when it flew its maiden flighton March-5 1936, and every single Spitfire built thereafter hada Meredith Radiator tucked under one wing.
The extra thrust developed by the radiator from waste heat easily made up for the drag of having it out there in the open.
So the p-51 was a somewhat poorly executed copycat affair. But make no mistake it was an excellent fighter; among the best ever.
But Iprefer to raise the engine efficiency by lowering the exhaust Temperature, rather than wasting a lot of hay on inefficient horse that just convert most of it to HS.
FTA: “We anticipate the thermoelectric voltage using our design to be about 100 times larger than what others have achieved in the lab,” Stafford added.
That’s nice and all, but current/power capacity is what’s needed.
As someone who has actually done car exhaust work, I doubt an exterior pipe coating of less than a millionth of an inch will survive long enough to be useful.
Apparently these researchers don’t realize the confusing mess that is current vehicle exhaust systems. Catalytic converters need to be hot to work effectively. Nowadays engines can run very efficiently, relatively, which is a problem. Extra air can be added so there’s enough oxygen for the catalytic to work, which cools the exhaust thus reducing effectiveness. There are combustion products that require a hot catalyst to be converted, endothermic reactions. So, the engine runs slightly rich to let through some unburned hydrocarbons, providing exothermic reactions which yield sufficient heat. Some engine inefficiency is thus built in for pollution reduction.
You end up with exhaust being no hotter than it has to be, with water frequently seen dribbling out of tail pipes. There’s been a changeover to stainless steel due to exhaust pipes rusting away from the inside. There’s not much available energy anyway.
You might be better off on the other end, the radiator throws off a lot of heat. Even more with modern engines, as they run hotter to be more efficient. Thermostats, which set the temperature limit at which coolant is sent to the radiator thus control the engine temperature, used to be rather low, 160-180°F. Nowadays engines run so hot the limit is the coolant, they’re talking about switching to something other than water-based to go higher that 220°F with a pressurized system. The question becomes, is there enough energy available to make it worthwhile to switch to a thermoelectric energy recovery unit instead of a radiator?
But then I wonder how one can recover such “waste” heat, as the goal is to dump the heat to the atmosphere and do it quickly. How can that be done while extracting energy?
Dave Springer says:
September 29, 2010 at 4:45 am
Coat the radiator with this material also.
Picures of Russian Lamp thermoelectic generators
http://www.radiomuseum.org/r/unknown_thermo_generato_tgk_3tgk.html
Please Everyone! We Must Think Positively About All This! We went from vacume tubes to transisters to integrated circuits and 1.21 gigabites at the drop of a hat. Now it’s time for something new. Don’t be negative and put the quash on it. Think positive! This is the 21st Century!
😉
AnonyMoose says:
September 29, 2010 at 2:27 pm
“Coat the radiator with this material also.”
Radiator might not be hot enough (typically 190F) to get any appreciable efficiency. If it is then we got a real winner. Holy grail of solar electric generation is to do it with water at or just over boiling point (low pressure) because it’s so cheap and easy to handle at that temperature & pressure (store it in an off the shelf hot-water heater) plus you can store a buttload of energy in a small volume due to latent heat of vaporization.
This seems to be an answer looking for a problem. The easiest way to extract the energy from a car’s exhaust system is to use current technology, to wit, an exhaust turbine commonly called a turbocharger. Instead of connecting the turbine to an air compressor connect it to an alternator, basically a small portable turbo-alternator electrical generation plant. I vaguely remember that the (non turbo) supercharger on a Mercedes McClaren (5.4 litre V8) requires over 200 bhp from the engine at full power, so an equivalent turbocharger, measured in output gas flow, should need about the same. 200bhp equals approximately 150 kilowatts, or 1500 100 watt lightbulbs.
By designing cars with a small ICE, to be used basically as a heat generator but connected to the drive wheels to use its 35% efficiency, passing the exhaust gases through an exhaust turbine connected to an alternator which then drives an additional electric drive motor (both at 90+% efficiency) most of the “waste” heat could be retrieved and usefully used. Even if only 1/2 of the waste heat could be extracted the overall efficiency of the engine could be increased to ~70% of the input energy. Simple and doable now without needing computer models to generate a possible hypothesis.
Are there obvious problems? Certainly, but these are merely simple engineering problems that our clever mechanical and electrical engineers could work on now, not wait for some possible breakthrough in “nano-technology”.
This article is a splendid demonstration of the strong force of scientific illiteracy- it’s just bloody thermocouple.
There is a lot of wasted energy in autos period. Much of it, as several pointed out, is low level heat energy that is hard to harvest.
One place being looked at is the car’s kinetic energy. Hitting the brakes and converting 4,200Lbs@60mph into undesirable waste heat via friction is primitive at best and an enormous waste of energy. High mass rotors harvesting the energy and air compression are being looked at, and the rotors seem promising.
This is an interesting theory. There could be a lot of uses for it if it overcomes a few challenges.
No kiddin’ I had a neighbor that let me in on his big secret. A generator and an electric motor plugged into each other. He was serious. He figured that as it picked up speed, he could harvest energy off of it. What? Do I want in on it?
I noticed a few comments about how the heat-difference drops to 0 at small distances and figured it would be best to clarify: The direction of the potential difference seems to be determined by the relative phases of the parts of the electron-wave. That, in turn, looks like it is determined by the direction in which the electron which interacts with this thermocouple is moving as it reaches the rings. Summing these potential-differences, that means that equal numbers of electrons from both sides will cancel, giving 0 V total. More heat on one side is faster random motion of particles on that side. This implies that those particles will hit the thermocouple more often.
Any given molecule will have a very small heat-difference across it, but that is to be expected: You don’t get much power out of a single molecule. Stacking them, though, you can get something. Still, I would really like to see the efficiency and price for these things.
From Richard on September 29, 2010 at 5:39 pm :
Except what makes turbines spin is the speed of the gases moving through them. Four stroke engines have a piston stroke just for pushing out the exhaust gases. Anything that restricts the exhaust flow will reduce the engine efficiency, which includes catalytic converters thus that’s an additional trade-off of efficiency for pollution control. Restrict the flow with a turbine and the engine will burn more fuel to power the exhaust stroke, creating more heat getting dumped at the radiator and a net efficiency loss.
George E. Smith says:
September 29, 2010 at 8:03 am
So the space probes are still working; that’s wonderful.
I think I have said several times here at WUWT, that using “electricity” to create “heat” should be a felony. [–snip rest for brevity–]
Well, I dunno, George.
Have you tried sucking on a piece of coal, coke, charcoal, wood, peat, or a hunk of dung lately? :o)
Don’t get me wrong here, but radiant heat panels are quite efficient over other means of heat energy production.
See this: http://www.sshcinc.com/
Now, rubbing two sticks together to create a fire is, well, using electricity to create heat. The electricity of your nervous system, which causes your muscles to contract and relax is using electricity to create heat.
Will you now submit yourself to the U.S. court system for being a felon in fact all these long years?
A more effective design is the new generation of Stirling engines. The reason they never caught on was because the pressure of the working fluid had to be low to avoid blowing the seals on the connecting rod power was transmitted through. The new designs use piston mounted magnets reciprocating inside cylinder mounted coils. No connecting rod. A combined heat and power unit for domestic used is being trialed by Eon in the UK. It uses gas to run the system, heating the home and additionally generating about 1kw which is fed back onto the grid, reducing the electricity bill. They claim a 25% saving over traditional combi-boilers.
The problem with adapting this to automotive use is the comparitively low temperature differential of most of the heat coming off the engine, as pointed out by several people on this thread.
George E. Smith says:
September 29, 2010 at 8:03 am
So yes going either way from electricity to heat or back is stupid, and should be a felony
Since all methods of converting traditional fuels to electricity use that method, it sounds like you are advocating wind power and PV.
😉
Buy your stirling engine here (and thermoelectric fans etc)
http://gyroscope.com/StirlingEngines/
kadaka (KD Knoebel)
Thank you for your reply. I find that there are a number, of umm, misapprehensions in your post.
1. The primary source of scavenging in a four stroke ICE is the release of high pressure when the exhaust valve opens. this also generates a shock wave that continues to extract the combustion products even when the pressure has dropped significantly. The exhaust strokehelps to a small degree by allowing the exhaust valve to remain open longer, and the to permit more complete filling of the chamber during the induction stroke. 2 stroke engines work successfully without an exhaust stroke, albeit with reduced efficiency. 2 stroke engines can also be turbo-charged quite successfully.
2. Efficiency reduction through greater back pressure in the exhaust system. A standard turbo-charger does this already, and all it does is permit greater power to be produced from a very inefficient power plant. The overall efficiency is not increased but I would hazard a guess it is slightly (somewhat) reduced.
3. Efficiency reduction of some smallish amount is immaterial provided that the extra power produced by the turbo-alternator/electric motor combination is significantly more e.g. lose 10bhp but gain 20bhp, a net gain of 10bhp from the same amount of fuel. Incidentally CO2 reduction is a distinct possibility }:-)
The use of heat engines to power turbines in their exhaust is already commonly done e.g. the auxiliary power units in large aircraft and the related so called turbo-prop engine. It is also done on a larger scale in gas turbine electrical generating plants and for (primarily military) ship propulsion systems. Even the “pure” jet engine needs a power turbine in the exhaust to drive the compressors and these turbines become larger and larger as the by-pass ratio increases as in fan-jet engines.
A lot of people sound like they know what they’re talking about in these comments but no one has addressed my simple question, so I’ll try again. Repeating:
Rod Everson says:
September 29, 2010 at 1:50 pm
oeman50 says:
September 29, 2010 at 12:28 pm
Yes, the driving force for any thermocouple is the delta T between the hot and cold junctions, so even thermocouples have to obey the Second law of Thermodynamics. It is implied from the way this article is written we can just directly convert any heat that is lying around into electricity, not true.
Rod asks: I don’t understand. Are we talking about two different processes here? Look at the picture at the beginning of the article where a candle is directly heating the junction between two metals and is creating a voltage difference. That doesn’t seem to hinge on “the delta T between the hot and cold junctions.” Is the Seebeck Effect different from a thermocouple? Can someone clarify?
“”” Rod Everson says:
September 30, 2010 at 8:01 am
A lot of people sound like they know what they’re talking about in these comments but no one has addressed my simple question, so I’ll try again. Repeating: “””
Rod, If you have two different metals welded together to make one of these “thermo electric junctions”, you of course have to have a complete circuit to get any current flow. I’m sure that is self evident to you.
So if you have a complete circuit; and you also have a junction between tow DIFFERENT metals; common sense sys that you must have AT LEAST ONE other junction between two different metals.
Simplest case would be two wires, say iron, and copper welded together at two different junctions.
A current will flow; if, and only if, those two junctions are at DIFFERENT TEMPERATURES.
So yes the Seebeck effect can convert the DIFFERENCE between two juntion Temperatures to electric power.
Now if their are more than two differnt metals in the circuit, then the resulting current flow will depend on the Temperature of each junction.
If all junctions in the circuit have the exact same Temperature, then the sum of the thermal EMFs around the circuit is zero.
And no the seebeck effect is NOT different from a thermocouple.
Here’s a spin on this I haven’t seen here yet:
Can these be used to eliminate waste-heat and cool down spacecraft? This gets me excited for two reasons:
First, keeping the temperature low is very important for satellite-based particle-detectors, and those directly impact on my work.
Second, I was looking through ideas for space-lift and travel, and one idea that really stuck was the Gaseous Nuclear Light Bulb engine. It looks workable, except for the waste-heat problem which looks like it would fry everyone and everything aboard. Mix that with the recent discovery of a possibly habitable Earth-like planet nearby and you can see my excitement about a possible way to cool down in space.
“”” tallbloke says:
September 30, 2010 at 1:33 am
George E. Smith says:
September 29, 2010 at 8:03 am
So yes going either way from electricity to heat or back is stupid, and should be a felony
Since all methods of converting traditional fuels to electricity use that method, it sounds like you are advocating wind power and PV.
😉 “””
Well hell no Tallbloke; but you have perhaps captured me in the act of exaggeration !
I plead that in the case of converting combustible fuels through inefficient heat engines to good clean real energy like electricity; the initial combustion Temperatures are so high compared to exhaust Temperatures, that even with less than the Carnot efficiency; a respectable conversion can take place.
Wind of course is actually a gas turbine engine, where sunlight provides the energy to heat the working fluid (air) over a gigantic volume, and direct a very small portion of it through the turbine blade to extract a minuscule amount of the original solar energy.
Well you look at the Temperature difference that may exist between say land and sea air masses, that cause winds; and you see how small the Carnot Efficiency is going to be.
PV in principle could convert 100% of solar energy to electricity; but as a practical matter; we don’t have enough choice of solar cell band gaps to actually do that.
Silicon has a band gap (300K) of 1.106 Volts versus 0.67 for Germanium. GaAs, is 1.47, GaN is 3.3 volts.
Einstein’s E.lambda product is 1.23980 Electron Volt Microns.
So a one micron wavelength Photon is not sufficient energy to activate a Silicon photo diode (solar cell) but GaAs would work.
So you need more than the band gap photon energy to get electricity; but unfortunately if you have more than the band gap photon energy; you don’t get any more electrons liberated, and the extra photon energy ultimately ends up as waste heat.
If my somewhat rusty memory serves, it has something to do with something called the Lamb Shift.
So you have to use a multijunction cell to extract energy from more of the solar spectrum; and even then you have a problem, because you have to effectively separate the correct parts of the spectrum and send them to the correct junction. It does you no good having a Gallium Nitride junction, if the shorter wavelength higher energy photons from the solar spectrum get stopped by some lower band gap material.
So MJPV cells are very tricky technology.
But I’ll let you go from heat to electric; so long as you are burning something that is hot enough. Steam turbines are very well developed technology.
But you understand how wasteful it is to go the other way; so electricity ought to be preserved for things electric; rather than cooking. Gas is much better for cooking than electric anyway. [George . . ]
Rod Everson says:
September 30, 2010 at 8:01 am
“I don’t understand. Are we talking about two different processes here? Look at the picture at the beginning of the article where a candle is directly heating the junction between two metals and is creating a voltage difference. That doesn’t seem to hinge on “the delta T between the hot and cold junctions.” Is the Seebeck Effect different from a thermocouple? Can someone clarify?”
To extract electrical power there has to be an electrical circuit with (at least) two junctions, one at a higher temperature (T1) than the other (T2). The delta T is T1-T2. The maximum possible thermodynamic efficiency is 1-T2/T1. So for a car radiator at 90C (363K) down to ambient 20C (293K) the theoretical maximum efficiency of recovery of the waste heat is 19%. Though small, this could nevertheless be a worthwhile fraction of the engine’s useful work. But there’s an obvious snag. The waste heat from this process (>81% of the original waste heat) still has to be got rid of somehow at this lower temperature. The radiator can’t do it; if it could it would already have run that much cooler, and the engine could have been made more efficient to start with, dumping its waste heat at that lower temperature. A thermopile can’t do anything that a mechanical heat engine couldn’t do already (though it might be able to do it more conveniently or more cheaply).
The suggestion being made here is that the hot and cold junctions could be at the top and bottom of a rather thin film (with the “forest” in between. Nothing wrong with this in itself, but what people are pointing out is that unless the “forest” has an astonishingly low thermal conductivity, such a thin film will have a very low thermal resistance and be unable to maintain more than a uselessly small temperature difference without a huge parasitic heat flow, which provides no useful power.
“”” 899 says:
September 30, 2010 at 12:49 am
George E. Smith says:
September 29, 2010 at 8:03 am
So the space probes are still working; that’s wonderful.
I think I have said several times here at WUWT, that using “electricity” to create “heat” should be a felony. [–snip rest for brevity–]
Well, I dunno, George.
Have you tried sucking on a piece of coal, coke, charcoal, wood, peat, or a hunk of dung lately? :o)
Don’t get me wrong here, but radiant heat panels are quite efficient over other means of heat energy production. “””
Well 899, you are completely missing the point. I AGREE with you that converting electricity to heat can be extremely high efficiency; the problem is that going the other way is not nearly as efficient so going back to heat crap from pristine electric is to be avoided if possible.
The less ELECTRICITY we WASTE by using it to make HEAT, the less EXPENSIVE ELECTRICITY we will NEED.
HEAT we already have PLENTY of; so lets use it as HEAT ! (whenever possible).
George E. Smith says:
September 29, 2010 at 11:29 am
“”” A C Osborn says:
September 29, 2010 at 10:08 am
Eric Gisin says:
September 29, 2010 at 7:55 am
David Socrates says:
September 29, 2010 at 11:38 am
I am surprised that nobody has yet commented that the above claim is complete and utter nonsense.
You both obviously didn’t bother reading my 1st post, which has a link to an article showing that BMW have worked on this.
http://www.i-sis.org.uk/harvestingWasteHeat.php
and as I said they are not the only ones, one Truck company has retrieved 1Kw of electrical power without any engine losses.
A C Osborn said on October 1, 2010 at 6:22 am
You … obviously didn’t bother reading my 1st post, which has a link to an article showing that BMW have worked on this. http://www.i-sis.org.uk/harvestingWasteHeat.php and as I said they are not the only ones, one Truck company has retrieved 1Kw of electrical power without any engine losses.
1kW of electrical power without any engine losses? Wow! … All I can do is to expand on what I have said briefly previously (September 29, 2010 at 11:38 am).
An ICE is a heat engine. It draws heat from a higher temperature source (burning fuel) and delivers heat to a lower temperature sink (the environment, primarily via the vehicle’s radiator and exhaust systems). In doing so it generates mechanical power. A thermopile is just another kind of heat engine. It too must draw heat from a higher temperature source and deliver heat to a lower temperature sink. In doing so it generates electrical power.
Neither of these heat engines nor any other heat engine that could ever be constructed can possibly ever be 100% efficient. This is not because of engineering limitations that might one day be overcome. It’s because the Second Law of Thermodynamics limits the % efficiency of a heat engine to an absolute maximum given by the very simple formula 100 x (T2-T1)/T2 where T2 is the higher (source) temperature and T1 is the lower (sink) temperature, both temperatures being measured in degrees Kelvin. You can see immediately from this formula that a heat engine could only be 100% efficient at converting heat to mechanical energy if T1 was 0 degrees Kelvin. This may be very nearly achievable in space but obviously not in the world of transportation!
For an ICE in our real world, the typical upper temperature T2 is around 1000K (burning fuel) and the lower exhaust gas temperature is around 350K. Putting those two numbers into the above formula gives a maximum theoretical efficiency for such an engine of 100 x (1000-350)/1000 = 65%.
Now let’s examine the proposal to use a thermopile as the heat sink of an ICE so as to tap in to the ICE’s ‘wasted’ heat and increase the overall efficiency of the vehicle’s power system. Yes of course the thermopile will generate some additional (electric) power but (and it’s a huge ‘but’) it has only got the much lower temperature waste heat from the ICE to play with, the temperature of its heat source being the ICE’s sink temperature (only 350K in the above example). If the thermopile sinks heat to an ambient air temperature of 288K (15degC), the maximum theoretical efficiency of the thermopile would be 100 x (350-288)/350 = 18%.
So in this ideal world of a perfect ICE delivering 65% of the input fuel’s power and a perfect thermopile delivering a further 18% there would indeed be a useful gain in engine system efficiency. But in the real world right now we have an ICE efficiency of around 33% (due to limitations of materials and compromises in construction, making the engine as light as possible and minimizing cost) and a thermopile efficiency of around (1% to 3%). On the basis of this analysis, it would almost certainly be better to work on ICE improvement to get the ICE nearer to its theoretical maximum and this is, of course, exactly what the world’s manufacturers are doing all the time.
Talk of thermocouples is just plain marketing hype centered around the ‘green agenda’. I guess it must be doing wonders for vehicle manufacturers’ sales.