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Nanoantennas: Solar arrays that absorb energy even in the dark!!

| Monday February 11th, 2008 | 86 Comments

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A collaboration of physicists, scientists and businesses have teamed up to create cheap and highly effective solar cells on a nanoscopic scale. Spearheaded by the Idaho National Laboratory, this team is onto a fresh way of producing solar panels that can continue to absorb energy even after the sun has set. The technology, not only efficient at nearly 80%, will also be cheap to manufacture, at estimated pennies a yard.
A specialized manufacturing process will stamp tiny square spirals of a conducting metal onto a think sheet of plastic that have been coined “nanoantennas.” At the slight width on the order of 1/25 the diameter of a human hair, these nanoantennas can absorb energy produced through the infrared spectrum. Infrared energy is produced in massive quantities by the sun, a portion of which is absorbed by the earth only to be released as radiation after the sun has set. These nanoantennas can absorb energy from both the rays of the daylight sun and the heat radiated from the earth at a higher efficiency than modern solar cells.


Steven Novak, a physicist at the Idaho National Laboratory spoke on this technology he is working on at the National Nano Engineering Conference in Boston. He said, “I think these antennas really have the potential to replace traditional solar panels.”
The technology simply mimics that of your cell phone or television antenna, absorbing energy by resonance. The theory that has born the research to produce these nanoantennas was based upon this platform; just make an antenna small enough to absorb the miniscule wavelengths produced by electromagnetic radiation.
The technology behind these atomic sized power modules is nothing new, but it has taken many years to discover an efficient way to print these miniscule spiraled antennas. It wasn’t until the inception of booming advancements in nanotechnology that this fine concept was taken from the theory to the tooling with production of these nanoantennas. The team at the INL forecast seeing the antennas produced akin to that of foil or plastic wrap in rolls of highly efficient solar cells. The team has been able to demonstrate an imprinting process with six-inch circular stamps, with each stamp containing more than 10 million antennas.
Instead of pairing this technology up with conventional solar cells to give them a boost in efficiency, the developers decided instead to make the nanoantennas independent energy harvesters. The team has estimated that individual nanoantennas are capable of absorbing nearly 80 percent of the available energy bombarded onto us daily by the sun. That is a staggering number compared to the conventional panels producing at around 20 percent.
Nanoantennas are not limited to silicon mediums, the circuits can actually be made from a variety of conducting metals and the antennas can be printed onto very thin and flexible materials such as polyethylene. The team has also estimated that the nanoantenna arrays can be available for as much as an inexpensive roll of carpet.
Although the physics of one resonating nanoantenna is certainly achievable, the trick to making this work lies in the matrix of complex vast arrays. The trouble will be in predicting the properties and perfecting the design before tackling the manufacturing obstacles that lie ahead. Multiple antennas create complex and sometimes unpredictable interactions. To jump this hurdle the researchers are developing a computer model of the resonance in these invisible structures, seeking out ways to fine-tune the efficiency of an entire array through tinkering with the materials and shapes of the antennas for example. “The ability to model these antennas is what’s going to make is successful, because we can’t see these things,” says Novack. “They are hard to manipulate, and small tweaks are going to make big differences.”


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  • http://www.europeantenders.com Tenders

    Very interesting blog! Thanks

  • Joe

    This idea was thought of a long time ago and the federal government never wanted to put any money into it, because it was obvious that it was a better way to go. For the originator look up Lepcon, Lumeloid, and Alvin Marks.

  • Ramsey Frist

    Offhand, the proposed device seems to defy the second law of thermodynamics. More information is needed. Where is the increase in entropy? Do these things radiate even longer wavelength photons? The article implies that you could stick one in a beaker of water and the water would freeze while electric power is extracted. The universe does not work that way.

  • Cristian Ioan

    Ramsey is right!
    But of course, we learned in school that the Second law of Thermodynamics is not absolute, like the fist.
    So a Maxwell Demon could make possible such a “perpetuum mobile” of the second type.
    And even if this is not possible in practice, nanoantennas would still make high efficiency photocells for the far infrared, without breaking the Second law ..

  • Ramsey Frist

    I know of no exceptions to the 2nd law of thermodynamics?
    Lets do a thought experiment with one of their perfected devices:
    Place two glasses of water both at the same temperature in an insulated container with the device in one. Connect its electrical output to a resistor in the other glass. If the device worked the first glass would spontaneously get colder and the second warmer. This never happens in the real world. This to me proves that it cannot work.
    For a mechanistic explanation one hangup is with the hypothetical diodes. If one could make a diode with such a low forward voltage why bother with the antennas? Thermal motion of the electrons would drive them through these hypothetical one way valves. Maxwell’s demons can not work and never will.

  • Gary

    What would happen if a highvoltage field is established between two collector plates. A third plate is heated by whatever scource and placed between the two collector plates. The em radiation from the black body then effecting the dielectric properties of the highvoltage field at a frequency determined by it’s heat content. Would the emitted em waves then show up in the hv conductors for harvesting?

  • http://nanospace.org Steve Watson

    Guys; Think of this as an RF antenna tuned for approximately 370THz (the center frequency for the energy being emmitted from our sun). It follows Maxwells equations and resonates the same as your TV antenna. (See research done by Dr. John Bokris at Texas A&M in 1996). Nanoantennas have actually been built and shown to resonate at light frequencies.
    The difficulty is constructing the nanoantenna with a tuned wavelength at this frequency in such a manner as to be able to collect and the rectify the energy obtained.

    • http://www.aitkeninternational.com/ Gerard J. Aitken IV

      Hi Steve,

      Your name sounds familiar and I wanted to know if you had worked with Dr. Marks in the past on Lumeloid TM Technologies?

  • Ramsey Frist

    In measuring the efficiency I believe they used IR from a laser turning low entropy coherent light into heat. In absorbing high entropy black body radiation or sunlight would they be any more efficient than black painted tin? With fast diodes with incredibly low forward voltage they might be able to rectify laser light but not black body radiation.

  • Nick Butler

    Hey
    What are you guys thinking!
    This can stop global warming!
    You are such nerds! “This wont work because of law of Thermodynamics” Thats how you sound

  • http://vulvox.tripod.com protn7

    The technoilogy is not really credible since no rectifier for the proper frequcny exists. With no rectifier the project cannot work.

  • WK

    If it’s the law of thernodynamics, then these top scientist will be stupid to waste their time and money, and you without any credentials dispute them. You are arguing high school physics with scientists.

  • WK

    Ultra capacitors can handle high frequency, what the need is a fast recifier, this is the last step, they have to store this absorbed energy first.

  • Ramsey Frist

    Dear WK, Why do you assume that I have no credentials. I hold a Ph.D. in Physical Biochemistry and I taught thermodynamics for 34 years.
    Scientific laws are empirical based on observation. No one has ever observed an exception to the 2nd Law. Think about it, if it worked one would be able to use the same energy over an over, heat to electricity and back to heat after turning a motor or lighting a lamp. It will usher in a new world with new physical laws. I am betting that this nanoantenna thing will never work and the DOE wasted a lot of money that could have been spent on worthwhile research.

    • Paul

      The thing is, the “laws” of thermodynamics don’t work at a quantum level. Otherwise the universe wouldn’t exist : the Big Bang defies the laws of thermodynamics.

      There’s no known reason why entropy should always increase.

      However, taking the long-term view, what these nantennae are providing is a temporary way to re-capture thermal energy emitted by warm bodies and convert it to electricity. No energy is being created; on the contrary, taking into account the energy lost during manufacturing, the overall entropy of the system does increase across the product’s lifetime.

      • Ramsey Frist

        Everything started at the big bang, space, time, and the physical laws. Ever since the entropy of the universe has been increasing and the 2nd Law of thermodynamics holds even at the quantum level. Not only can you not get energy for free but you cannot even break even. This proposed system cannot work in our universe.

  • Richard

    Have they tried the technology used on the new high tech batteries used at Phoenix motor cars.
    http://www.b2i.us/profiles/investor/fullpage.asp?f=1&BzID=546&to=cp&Nav=0&LangID=1&s=0&ID=10701
    If they can recharge a batter used in a car in ten minutes, there might be a way to tie the two together…
    Once all the problems are solved on how to transfer the energy safely into the battery.

  • Will

    Fantastic invention! This is what I dreamed of as a child, at 14yo. when I drew up plans for a solar car. In resurch, found that the first solar car rolled down Pennsylvania ave. and got burried by the government in 1918. The government, (I’m now 50), is still not smart enough to figure out how to make money out of the Sun, and now wants to use “clean burning coal”? Kudos to you, I want this technology to thrive.

  • jagdish

    can they work during rainfall.what is the cost of each nano antenna ,what are materials required to make an antenna

  • Bob

    Would someone please explain why antenna's work for radio, microwave, visible but somehow, not for IR? Obviously the laws of thermodynamics apply in all cases but why is IR radiation impossible to gather in an antenna as some here claim? Or asked another way, if they work for IR in a controlled experiment, why would they not work for IR radiating from the earth? Is that not real energy also? Is there a difference between a 10 micron photon emminating from the sun rather than the earth? Above the atmosphere, about 50% of sunlight is in the IR. Are you saying an IR antenna would not work to convert that solar energy?

    • Ramsey Frist

      Antennas, nano or otherwise, can capture a bit of energy from coherent, low entropy, radiation from a laser, radio transmitter, microwave transmitter, etc. but not from high entropy black body radiation. There are mechanistic reasons why the proposed antennas won't work such as the forward voltage of the diodes or random phase differences in the antennas. But the why does not matter; thermodynamics simply says it cannot work. All engines must operate with an entropy gradient. To extract energy one must increase the entropy of the universe. With their hypothetical system there is no net increase in entropy anywhere, in fact, they would cause a net decrease in entropy. If they worked one could take these magic antennas and put them in a snow bank and use the electrical energy to warm your house. Energy does not flow on its own uphill. Heat pumps require energy and they increase the entropy of the universe.

  • Bob

    Thank you very much for the answer. You might be right but I am still bothered.

    You say “thermodynamics simply says it cannot work” . I agree that thermodynamics are never violated however, I am having a hard time (and I have a physics degree) seeing how this violates the second law. You seem to say we are talking about extracting energy at equilibrium from a closed system. I do not think we are talking about equilibrium and I think the system is open. Any examples where an antenna is contained in a enclosed perfect container would of course get to an equilibrium state quickly but it would both radiate and absorb at the same rates. I think these are strawman arguments because we do not have a fixed amount of radiation doomed to radiate and absorb between antenna and the system. We have a huge source and a continuing flux.

    The sun is black body incoherent radiation. We have no trouble using it. There is nothing special about the IR wavelengths. I do not think the IR source of the earth is random. It is generally radiating up and moving to space. Yes, some scatters back but that can be blocked. Government data separates out the updwelling and down scattered IR. They don't generally cancel. From space, earth would appear like the sun in longer wavelengths. Blackbody spectrums all have the same shape. You are implicitly suggesting that optical wavelength antenna's would not work with sunlight either. Also, imagine a sun much much larger but radiating at the 300K blackbody spectrum such that the same total energy was released (or even more). Would you say such a sun can impart no useful energy? If the IR emitted from the Earth did no useful work the planet would be much cooler. Randon Phase changes can be dealt with by filtering. Individual photons are not high or low entropy. Diodes are not a fundamental physics issue.

    You mentioned a snow bank. A large Sterling engine could use even a small temperature difference between snow/ground or snow air to heat a house. Inefficient yes, impossible no. I doubt if anyone would have a difficult time imagining these antenna's used to make IR radiation efficiently by putting in energy. If so, they should be able to absorb it also and give out energy. Phase variations and such are just engineering details and not fundamental physics. If the earth suddenly emitted hemispherically upwards 400 W/m^2 in the radio spectrum, antenna's should be able to get the energy. Radio photons are much much weaker than IR photons yet they have no trouble exciting electrons in metals. I want to find out the detailed thermodynamics of that and why you say IR is different for the same energy flux. Is it just the randomness issue?

    I wouldn't want to stand in front of a 1 megawatt IR beam of coherent photons even if their temperature was only 300K. Thanks.

    • Ramsey Frist

      Back to basics .. maybe. Using Sterling engines or photovoltaic cells to capture some free energy (as in Gibbs free energy) from sunlight does not violate the 2nd law because there is an entropy gradient between the incoming lower entropy (bluer) photons and the higher entropy (redder) photons or heat leaving the engine or photocells. That is, there is entropy as “waste heat” released to the surroundings in the process. In the proposed antenna system photons are supposedly converted to electrical energy with no redder photons released. This means a net decrease in entropy in the system plus surroundings (the universe). That is not permitted in our world.

      In the snow example there is no temperature gradient (except one supposedly created by the antennas themselves, i.e., heat would be withdrawn from the snow). Everything over absolute zero emits some black body radiation. They imply that by using their system energy would spontaneously flow from a snow bank to a warm house. In their publications and videos they say there antennas might be used to cool computers or cars and at the same time use that energy to heat something else. Sorry, our universe does not work that way.

  • Bob

    Ah ha. I see where your assumptions are. In the original source, it was stated that waste heat is generated at even longer wavelengths. Antenna's are very efficient but nobody says they are perfect. There are losses all along the conduction path as well as in whatever load is being driven. Overall,
    entropy increases. You also stated that radio waves ect. are low entropy but all black body radiation is high entropy. A 300K IR source in deep space is low entropy compared to near absolute zero. In principle I could broadcast a radio signal on a 10um carrier wave. Would my IR antennna receive it? I don't think they made any assumptions regarding antenna's that are special.

    I think it is important to see how a 1 Megacycle RF photon creates waste heat in an antenna/radio system. Except for directionality and phase, which we can control with filtering, the RF photon has
    higher entropy than an IR photon. If the antenna is at 300K, random thermal noise should swamp the
    (typically) small signal. The RF photon is a lot colder than the antenna. Compare k T fermi to hf.
    Yet, it works and there is waste heat because all conductors are imperfect. In fact these systems are heat engines but more efficient than macroscopic heat engines we usually think of. The Carnot efficiency of an antenna system is high but not 100%.

    Regarding the snow, heat is not being drawn from the snow. IR radiation is passed through from the earth
    unless you contend that the snow is a perfect reflector and seals up the earth's heat. Put a nice insulated dome over the snow with a tight seal to the earth and the interior will warm up and melt. In fact, the air outside may be colder than the snow in which case you should admit an antenna at the air temperature should be able to pick up energy from the ground by radiation.

    BTW, they talk of cooling rooms that get hot. You can do that easy by using thermal walls which conduct heat to the ground in summer and from the ground in winter. So, why can't an IR antenna do that also? One can conduct excess heat away by conduction but not by radiation? Their examples all had temperature differences as far as I could tell. One final thought, suppose I have a perfect black body cavity at 300K. Inside is a IR antenna tuned to 10um at equilibrium. There is a set of wires leading out without leaking heat. The outside is at 2.7K. What happens if the wires are connected to a load outside and if they are not?

    • Ramsey Frist

      Dear Bob, Somehow you seem to be getting bogged down in mechanistic thinking. In my thought experiment the IR is would be coming from the snow. Any from the earth would melt some snow. Think of a snow bank as a black body at zero degrees C that the nanoantennas are immersed in. Do you really believe that energy will spontaneously flow from the snow bank to a warm house?

      In any case, if one could make diodes with such a low forward voltage that they could rectify the voltage produced by a single nano-antenna there would be no need for the antennas. One could simply put a bunch of these diodes in series, paint them black, and each would act like a one way valve allowing electrons to be driven through by their thermal motion. Maxwell's demons don't work and never will.

  • Bob

    I never said spontaneously. It won't just happen on it's own. But you seem to contend that it is impossible for an antenna to pick up any photons from this IR and generate power. I have seen data where IR at 10um wavelengths (300K) excite DC currents in antenna's at I believe to be at 300K.

    What if I took the IR from 100m^2 of snow and focused it on a one m^2 antenna array. Are you saying no matter how much flux (which determines total energy of 300 W/m^ * 100 M^2= 30000 W) I cannot get anything out? If so, that just seems wrong.

    BTW, the snow without the earth would quickly lose it's heat and approach near absolute zero. It is the continuing IR emmanating off the earth, ultimately from the sun, that keeps the biosphere in the range it is so there is a continuing flux of energy supplied. It is an open system. The power density of the IR from the snow is about 300 W/m^2. Again, this is really the earth keeping the snow from getting too cold. On balmy nice days (and nights) the earth gives off about 400 W/m^2.

    But the whole snow debate is as aside. The original paper was talking about excess heat from a computer or a room that gets too hot. Surely in those cases the antena's could shunt away heat.

    • Ramsey Frist

      No I afraid they would not shunt away heat by generating electricity. With non coherent black body radiation all the currents set up in the nanoantennas would be out of phase with each other so there would be no net current without a functioning diode at each antenna. Such diodes don't and cannot exist. In your earlier proposal you asked what would happen if one placed the antennas in a 300K cavity and connected them to a load at 2.7K. Without functioning diodes nothing would happen as the AC outputs of the nano-antennas would cancel each other out.

      It really is unnecessary for me to try to argue by showing where the mechanism fails. The 2nd law says that energy will not flow from one body to another without an increase in entropy. If their system could work one could collect the the IR from one body, convert it to electricity, and use that to heat another body without any input of energy thus ending up with lowered entropy (the first body would spontaneously cool while the 2nd would warm). This is forbidden.

  • Bob

    RF: No I afraid they would not shunt away heat by generating electricity.

    Bob: Okay. You have made your point. You believe an IR antenna will under no circumstances conceivable generate elctricity.

    RF: With non coherent black body radiation all the currents set up in the nanoantennas would be out of phase with each other so there would be no net current without a functioning diode at each antenna.

    Bob: The sun is non-coherent black body radiation just at a higher temperature. The directionality comes from the fact that we are far away. Even so, you are claiming that diodes cannot exist that rectify the radiation. I suppose such a diode would be a “Maxwell's Demon” in your mind and thus cannot exist.
    At the power densites we as discussing, there is about one photon per square micron impinging on my antenna every 50ps. A 30THZ diode can switch in 0.03ps. Basically, I think this means that there is usually going to be only one photon on average at a time in any antenna element.

    So, exactly at what frequency would all diodes fail?

    RF: In your earlier proposal you asked what would happen if one placed the antennas in a 300K cavity and connected them to a load at 2.7K. Without functioning diodes nothing would happen as the AC outputs of the nano-antennas would cancel each other out.

    Bob: Replace my antenna in the box with a piece of copper. Connect the copper to the outside. What happens? Heat drains away to the colder environment. Suppose I put a thermocouple in the path and generate a small current. What happens. I make a small amount of power on the way. No violation of the second law. But, you say the hotter body can't lose heat to the colder body by a radiation path but it can by a conduction path?

    RF: It really is unnecessary for me to try to argue by showing where the mechanism fails. The 2nd law says that energy will not flow from one body to another without an increase in entropy.

    Bob: The details are important and you seem to just quote the law without checking if you may be misapplying it in this case.

    • Ramsey Frist

      Lets take your piece of copper at 300K and connect it to another piece that leads to the cool outside. Heat (energy) will flow to the second piece and be radiated away to cooler surroundings. The energy becomes more dispersed, less ordered, more randomized, or in thermodynamic terms, entropy has increased. What the nano-antenna people are claiming is just the opposite. If their magic antennas worked as they hope one could gather energy from the IR background on the outside and use it to add heat to the first piece of copper creating more order in defiance of the 2nd law.

      These light trapping antenna schemes have been around for 25 years or more. But no one has yet to produce a nanowatt of power from any of them. Do a search for something called Lumeloid and check out these links:

      http://www.hbci.com/~wenonah/new/nsolcel.htm
      http://www.physics.bc.edu/Deptsite/news/antenna

      Maybe nano antennas or carbon tubes might someday be play a role in capturing solar energy but not until they find some way of satisfying the 2nd law perhaps by radiating away longer wavelength photons by some clever mechanism but the proposal that they have at present is futile.

      I do appreciate your thoughtful questions and arguments . Its been fun.

  • Bob

    RF:What the nano-antenna people are claiming is just the opposite. If their magic antennas worked as they hope one could gather energy from the IR background on the outside and use it to add heat to the first piece of copper creating more order in defiance of the 2nd law.

    Bob: As far as I can tell, they never said that. They are talking about residual heat, above normal, from hot roads, roofs, walls as they cool down towards the cooler air temperature. This is not equilibrium.
    They are also talking about residual heat from electronics, hot car engines, hot rooms all relative to cooler antenna's. It would be interesting to have an iR inventory of the environment to see where and how much and for how long these non-equilibrium situations last.

    Yes, there need to be a reference or a cooler antenna than the surroundings just like a solar cell would cease working if immersed inside the surface of the sun in equilibrium with its surroundings at 6000K
    (of course it would melt long before but you know what I mean).

    RF: These light trapping antenna schemes have been around for 25 years or more. But no one has yet to produce a nanowatt of power from any of them. Do a search for something called Lumeloid and check out these links:

    Bob: Small amounts (mW) of electricity have been produced by IR antenna's picking up IR fluxes from concentrated IR sources. They work. Not very efficient yet but real power. The diodes worked at 30THZ. BTW,Calling them scemes is unfair. This is an active line of research and the hundreds of scientists around the world working on IR and optical antenna's are not ignorant fools. Also, lack of a commercially available technology is not a measure of scientific validity. New technology, even if it is superior does not always get adopted.

    RF: Maybe nano antennas or carbon tubes might someday be play a role in capturing solar energy but not until they find some way of satisfying the 2nd law perhaps by radiating away longer wavelength photons by some clever mechanism but the proposal that they have at present is futile.

    Bob: The probems are engineering, not fundamental physics.

    RF: I do appreciate your thoughtful questions and arguments . Its been fun.

    Bob: Me too. Thanks for the discussion.

    • Ramsey Frist

      I must be burning out on this topic. I meant “high entropy IR.” in the last comment. Sorry.

  • Ramsey Frist

    Dear Bob, Please review the video and publications from INL. They clearly state that they expect perfected nano antennas to make electrical power (free energy that can be used to reduce entropy) from low entropy IR (“waste heat”). Not only that, they state that the antennas will cool their environment at the same time. That is, because they are converting IR into electricity they will be cooler than their surroundings and they may be able to be used to cool computers, or rooms, etc. So therefor they must be magic as they can cause the spontaneous flow of energy from cold to hot.

    The 2nd law says that for any process to occur in our universe entropy must increase. Again I ask, where in their proposed system is there an increase in entropy?

    By the way, thermodynamics is about as fundamental as physics gets. No one has found an exception to the laws of thermodynamics. If such antennas worked one would be able to build an perpetual motion machine of the second kind (Google “perpetual motion of the second kind.” you may find similar schemes).

    Here is a homework problem for you: Calculate the maximum voltage produced in a nanoantenna by the absorption of one IR photon. Compare that to the forward voltage of any known diode.

  • Bob

    RF: Here is a homework problem for you: Calculate the maximum voltage produced in a nanoantenna by the absorption of one IR photon. Compare that to the forward voltage of any known diode.

    Bob: This is not an easy problem simply because you have to make assumptions about the confinement of the photon to know it's voltage. The field for a 10 micron photon is about 1.6 mV/um but the actual voltage will depend on geomentry. It could be between 1 and 50 mV. Another way is to look at the
    photon energy which is 4.4x 10^-15 eV-s * 3 10^13 s^-1 = 0.12 eV (electron volts). So one photon could
    raise the potential of one electron by 120 mV. Some MIM diodes can have low VF however, it is not clear that the voltage even has to be greater than VF because the diode is not a perfect step function. It just needs to be non-linear which it is. The difference is a matter of efficiency, not functionality. Quantum wells could be tailored to have very low barriers in one direction and high in another if you want to sacrifice efficiency. So a small handful of photons, or with development, one photon, should be able to get over the barrier.

    But like I keep telling you- this has actually been done on a small scale. IR has been rectified. It's not a physical impossibility. I can't just scoff that off. It's happened.

    BTW, any cooling mechanism that works by physical conduction must also work by radiation under the appropriate equivalent circumstances.

  • Ramsey Frist

    I guess you are implying that if they can get it to work the 2nd Law is repealed. That would be true but I would not bet on that ever happening. Granted, nanoantennas have been used to transmit and detect coherent radiation but where has power ever been produced on any scale with black body radiation?

    BTW, their magic antennas supposedly will cool by absorbing IR from wherever they are placed.

  • Bob

    RF: I guess you are implying that if they can get it to work the 2nd Law is repealed. That would be true but I would not bet on that ever happening. Granted, nanoantennas have been used to transmit and detect coherent radiation but where has power ever been produced on any scale with black body radiation?

    Bob: Most papers use IR sources or lasers for convenience true, but the principles work. But remember that the IR sources are in the 300K range so I guess your complaint is random phase 300K IR vs. coherent phase IR at the same temperature. Is that your main objection? Do you define 'blackbody' as beyond usefulness, completely random or such?

    So, all I have to do is find one paper where any signal was useful based on non coherent source. Would that include 2.7K background radiation?

    BTW, you didn;t comment on my numbers above.

  • Bob

    I forgot to mention. In your microwave oven are a good jumble of random phases of waves bouncing around yet the water molecules act like little antenna's absorbing the energy. Funny thing is that the microwaves are much much cooler than the thermal energy of the water. So, can you explain how lower energy photons can heat up higher energy molecules?

    • Ramsey Frist

      OK, lets try yet another tack. Picture that you have a well insulated house with two equal size bedrooms with their windows shuttered. In the bedroom A you set up an array of the magic nanoantennas and run their power output to a space heater in bedroom B. Bedroom A will cool to a new lower temperature and bedroom B will warm to a new higher temperature (heat will flow back from the now warm room B to room A by conduction through the adjacent wall to establish a steady state). This temperature difference will be maintained with no input of energy from outside the house. One could now put a Stirling engine in the wall between the two rooms with the evaporator end in the warm room and the condenser in the cold room. Now we not only have created a free temperature gradient but we have a perpetual motion machine.

      Such things just don't seem to happen in our world. There is no free lunch.

      I think 50 mv is still well below the forward voltage of even Schottky diodes?

    • Technitron

      Bob,

      You should read the Investigation of resonance light absorption and rectification by subnanostructures
      by Guang H. Lin, Reyimjan Abdu and John O'M Bockris

      Chemistry Department Texas A&M University College Station, Texas 77843

      The paper was received on the 28th of February, 1996 and accepted for publication on the 3rd of April 1996.

      worked on it since 1994 with Dr. Alvin M. Marks and his private lab ARDI under a CIA R&D contract.

      This will answer some of the questions you've been debating over for the last few days on this forum.

      • Ramsey Frist

        To Bob as well. Please remember that I am not arguing against nano-antennas in general only against the use of IR radiation as presented by the INL people. It is conceivable that nano-antennas designed to absorb high frequency (low entropy) light and give off high entropy IR could trap free energy along this path. This would be analogous to the light reactions in plants or to the way photovoltaic cells work. As I said before maybe someday someone will develop a functional system that absorbs IR and gives off radio frequency photons?

        By the way, if it were possible to use IR as a free energy source surely some form of life would have evolved to exploit this by now.

  • Bob

    RF: worked on it since 1994 with Dr. Alvin M. Marks and his private lab ARDI under a CIA R&D contract.

    Bob: I'm confused. Are you saying you worked on nano-antennas? If so, why did you argue that if would be impossible to even rectify the IR at 30THZ? Even so, you just pointed me to a reference that proves it is possible. I will read that reference tonight.

    RF: Please remember that I am not arguing against nano-antennas in general only against the use of IR radiation as presented by the INL people.

    Bob: Well, it sure seemed like you were.

    So, basically, you agree that an antenna can be made to absorb IR or visible light. Your sole argument is
    what constitues a reasonable source of energy in which you can use them. You are arguing that if an antenna array is in thermodynamic equilibrium with the environment no energy can be extracted. I do
    not disagree and I strongly suspect your issues with the INL statements are really issues with rather exuberent PR statements taken out of context and misinterpreted. If, however, you are arguing that IR
    off a hot roof or road after sunset into a cool antenna is impossible, I disagree. I would further argue that the earth is a heat source for an antenna in orbit sitting at near 0K. I see no fundamental difference between a 600K to 300K heat engine to a 300K to a near 0K heat engine. Both are allowed by the first and second laws. In fact, the Carnot efficiency of the latter is higher being almost 1 as compared to 0.5.

    Now as to your two bedroom example. First, I am not saying you could do what you postulated against but there are some conciderations to think about. First, replace the IR with light and assume the walls are perfectly reflecting so the light keeps bouncing. Replace the antenna's with solar cells. What happens?
    The cells in the room convert light to energy which is pumped into the next room to make more light. So one room gets dimmer and the other brighter. Does this violate the second law? If so, why. One would expect the total energy is constant and entropy rises a bt as some energy is wasted along the way into IR.

    BTW, environmental IR energy is real energy which heats the earth and does useful work. It is just lower grade solar energy but it is not fundamentally the lowest grade energy possible so it can still be used. One can soak up solar thermal energy during daylight and let it generate power at night (this is done now with conventional heat engines) so it could also be done at possible higher efficiency using IR antenna's.

    What I can't find is a good argument as to exactly how any photon/electron conversion in any antenna, regardless of frequency obeys thermodynamics.

    Thanks for the reference.

    • Ramsey Frist

      Well, you sure are good at coming up with apparent paradoxes. First, don't confuse me with Tecnitron. He was the one that may have worked on nano antennas. Regarding the reflecting rooms, most ot the light would quickly end up as heat (IR) in the room with the photocells then the photocells would stop working. Some light would be added to the second room but its a one shot deal. One would have to look for the net increase in entropy in the additional IR in the first photocell room. Quite a different situation than the continuous maintenance of a temperature gradient by the magic antennas.

      I don't understand your “antennas not being in equilibrium” statements. If we focus the sun's rays on a boiler of a steam engine the only way the engine can extract energy is if there is a cooler place (the cooler surroundings) for the heat to flow to. When the nanoantennas are in a snow bank or in an oven or in the core of the sun there is no place for the heat to flow to. They are in equilibrium with their surroundings. Compare this to a photovoltaic cell or a Crookes radiometer. They both work by absorbing sunlight from one direction and giving off higher entropy IR to their cooler surroundings in all the other directions. Only a fraction of the energy flow can be captured.

      Back to my old question, in the INL nanoantenna system, where is the net increase in entropy? For any process to occur there must be a net increase in entropy of the system plus its surroundings (the universe).

  • Bob

    Thanks for clearing up the reference to working on antennas.

    RF: Well, you sure are good at coming up with apparent paradoxes.

    Bob: Thanks!

    RF: I don't understand your “antennas not being in equilibrium” statements. ..

    Bob: It's simple. A hot body radiates towards my cool antenna. The antenna resonates and makes electricity or even just acts as a waveguide to carry the radiation away, the antenna remains cool
    except for some inefficiency, and most of the heat does not raise the temperature of the antenna.
    I contend that whatever a heat sink can do the antennas could do.

    What is happening is that the heat is making electrons hot, not the lattice of the antenna atoms hot.
    Those hot electrons then become current and new electrons are heated.

    A photovoltaic cell pounded with single wavelength radiation just at/above the bandgap would be very very efficient as compared to now where 70-80% of the photons only make heat in the cell without making any current. The Carnot efficiency of a solar photon/electron hole pair is near 1. The rest of the losses are engineering details and not fundamental..

    RF: Quite a different situation than the continuous maintenance of a temperature gradient by the magic antennas.

    Bob: But I think the INL people assume some gradient to start with like a hot computer or a person's 98F skin vs. a cooler room or clothes or air temperature rising faster in a room than the walls can conduct the heat away. I think they also meant hot roofs/roads or warm ground against cooler antenna.

    BTW, you cannot possibly think everything around you is always in equilibrium? If so nothing would ever change.

    RF: Back to my old question, in the INL nanoantenna system, where is the net increase in entropy? For any process to occur there must be a net increase in entropy of the system plus its surroundings (the universe).

    Bob: Any process that works off a temperature difference, no matter how small, will always have an associated entropy increase unless it is a completely reversable processs which we can safely assume not in this case as there is always losses with generating power. Therefore, if there is an
    amount of heat absorbed off say a hot roof into my cool antenna, there is a Carnot efficiency and an entropy rise regardless of the mechanisms. The antenna is the cool side of my heat engine and the electrons in it are the engine. There are losses in conversion. losses in conduction and losses in the end use of the generated power. Most of the heat flows out with the electrons in the form of power.

    In the case of coherent 10 um (300K) radiation towards an antenna, say the antenna radiates at the same frequency. If the flux of the source is the same as the flux of the antenna nothing happens. If the flux is higher, say 10X, then the electrons absorb IR energy and get hot. That temperature would be used as the hot temperature for the Carnot efficiency equation and power would be generated.

  • Bob

    Technitron: Bob, You should read the Investigation of resonance light absorption and rectification by subnanostructures by Guang H. Lin, Reyimjan Abdu and John O'M Bockris

    Bob: Thanks. Sorry I did not see at first you were a different person. I will get that paper tonight.

  • Ramsey Frist

    What can I say? Have you looked at the INL publication? You can get a PDF from their site or simply dp a search of “ES 2008-54016.” They say one can both cool and make power at the same time. That alone is in defiance of the 2nd law.

    You say “heat absorbed say from a hot roof into my cool antenna.” What keeps the antenna cool? That is my major point; there is nothing that keeps the antenna cool unless you provide some way for it to emit longer wavelength photons than it is absorbing. Look at the antenna as if it were a steam engine with a closed condenser and both the boiler and the condenser are in the fire so they are at the same temperature. A steam engine can not work without a temperature gradient and in general any system cannot work without an entropy gradient.

  • Bob

    RF: What can I say? Have you looked at the INL publication?

    Bob: Yes, I read it over and over. I would like to contact them to ask questions directly. Have you done that?

    RF: They say one can both cool and make power at the same time.

    Bob: But to cool something does not mean the cooling instrument has to be cooler then the thing being cooled. It means it is conducting heat away. A heat sink cools but it is itself not cool and could in principle be used to power a themioelctric device as it is conducting heat away from something.

    RF: That is my major point; there is nothing that keeps the antenna cool unless you provide some way for it to emit longer wavelength ..

    Bob: Think of the electrons as cool water that carrier heat away. This keeps the bulk of the antenna from getting too warm. It has to get somewhat warm but I think the electrons carry awary the heat.

    RF: A steam engine can not work without a temperature gradient and in general any system cannot work without an entropy gradient.

    Bob: Granted but as I said I think they assume some gradient. If not stated it is implied.

    Anyway, I think I will contact them and ask.

    • Ramsey Frist

      Bob: But to cool something does not mean the cooling instrument has to be cooler then the thing being cooled. It means it is conducting heat away. A heat sink cools but it is itself not cool and could in principle be used to power a themioelctric device as it is conducting heat away from something.

      RF: ?? How can something cool if it is not cooler than what is being cooled? Heat only flows from high to low temperature. They predict that their nanoantannas will be used in clothing to provide a cool environment for the body and that heat energy will be used to power a Segway or whatever, all done passively without any other energy source.

      Bob: Think of the electrons as cool water that carrier heat away. This keeps the bulk of the antenna from getting too warm. It has to get somewhat warm but I think the electrons carry awary the heat.

      RF: Lets extend the steam engine analogy. We have the steam engine with its boiler and condenser at the same temperature. Assume the output shaft of the steam engine goes to a electric generator. Saying that the current will draw heat away from the nanoantennas and create a gradient is like saying that connecting a load to the generator will make the steam engine run.

      When sunlight falls on a photoelectric cell a potential difference is created whether there is a load connected or not. I am betting that shining non coherent IR on their antenna array produces no voltage.

      Goodnight

  • Bob

    RF: ?? How can something cool if it is not cooler than what is being cooled? Heat only flows from high to low temperature. They predict that their nanoantannas will be used in clothing to provide a cool environment for the body and that heat energy will be used to power a Segway or whatever, all done passively without any other energy source.

    Bob: Perhaps I am not being very clear. Think of a wall at room temp or 70F. You have a party and 50 peopel are in your living room. The air starts to heat up from 70. The walls start to conduct heat away, they don;t just immediatly rise to the air temp. They are a heat sink. If they are effective, the room stays comfotable, if not , it gets hot till the walls conduct away the heat after the party. Antennas on the walls might help conduct the IR away faster and keep the room from getting hotter. In that sense, they are cooling the room. Same as if you has a better heat sink than typical walls.

    RF: They predict that their nanoantannas will be used in clothing to provide a cool environment for the body and that heat energy will be used to power a Segway or whatever, all done passively without any other energy source.

    Bob: The human body is a thermal radiation source hotter than its environment. Of course one can use the temperature difference between body and air to make power. You can buy toy Sterling engines than run off th eheat of you hand with respect to the air. Antennas in clothes can convert trapped IR and make small amounts of power. To feel cool all that is required here is that the heat be conducted away. Low efficiency aside and thinking only in terms of principle, a network of water tubes powered by a Sterling engine off your body heat would do the same thing.

    RF: Lets extend the steam engine analogy. We have the steam engine with its boiler and condenser at the same temperature.

    Bob: This is a false analogy. I ,and I believe they are not claiming that.

    RF:When sunlight falls on a photoelectric cell a potential difference is created whether there is a load connected or not. I am betting that shining non coherent IR on their antenna array produces no voltage

    Bob: Then we can filter the IR until it is more coherent than not.

    BTW, IR from the ground heats up clouds. Clouds and air in motion cause lightning. Therefore, IR from the earth is already converted into electricity. If random phase is the only problem it is a problem that can be addressed by design and is not fundamental. Sure, it would reduce effectivness.

  • Ramsey Frist

    OK, I am worn out in trying to come up with a mechanistic explanation that meets with your satisfaction. All I know is if you have two bodies at the same temperature energy in any form will not flow from one to the other via any passive mechanism including nanoantannas. It requires energy to create order. If their mechanism (as they present it) does not work for transferring heat from the IR in a snow bank to a warm house it cannot work under any circumstance. If you can find one example of where power is made from non coherent black body IR please let me know.

    Filtering non-coherent light to make it more coherent? That would take a type of Maxwell demon and we know they don't work. Again, to create order takes the expenditure of energy and the creation of more disorder somewhere else. Where in their system would the order be “paid for” by an increase in entropy?

    One can consider the Earth to be one big engine. Low entropy sunlight drives the “boiler” and high entropy IR radiates out to cold space. There is a balance between energy arriving and energy leaving (otherwise the Earth would melt or freeze) but the increase in entropy permits the capture of some free energy which can create wind and storms, and give rise to living things (perhaps the lowest form of entropy there is). There is a higher concentration of order in an bacterium than in a star.

  • Bob

    RF:OK, I am worn out in trying to come up with a mechanistic explanation that meets with your satisfaction

    Bob: Me too. I am going on vacation for the weekend so I won't be responding.

    RF: Filtering non-coherent light to make it more coherent? That would take a type of Maxwell demon and we know they don't work. Again, to create order takes the expenditure of energy and the creation of more disorder somewhere else. Where in their system would the order be “paid for” by an increase in entropy?

    Bob: So, it is impossible to filter out light of certain polarizations? Hmm. I thought that was simple.
    Sure you sacrifice intensity but I know of no law that says radiation cannot be filtered out. Besides,
    in the paper I read last night that was earlier recommended yesterday to me, a light source that was not a laser was used to power an optical antenna after it was filtered. The light source was near single wavelength but was not coherent. A polarization filter was used to select photons in alignment with the antenna. It seemed to work just fine.

    Consider an antenna in a room at 300K which for convenience lets say is defined by a blackbody spectrum centered at 10um. Lets tune the antenna to 1um. introduce another blackbody source in the room centered at 1um and filtered to be reasonable coherent in one direction. Will the antenna pick up anything? I say yes. Now, tune it to 100um and introduce a source at 100um. Will it register? I say yes. Now, keep tuning the antenna closer to 10um. When, according to you, will it fail? ONly when the blackbody spectrums are identical?

  • Ramsey Frist

    One more try.

    Bob: The human body is a thermal radiation source hotter than its environment. Of course one can use the temperature difference between body and air to make power. You can buy toy Sterling engines than run off the heat of you hand with respect to the air. Antennas in clothes can convert trapped IR and make small amounts of power.

    RF: This statement may be a clue to your problem. The mini Sterling engine works on a temperature difference. There is a warm end and a cool end. The nanoantenna system as described has NO cold end nor can there be a cold end with an antenna. If anything the antenna would be warmed by the currents set up in them. They claim that if you put the antennas in a beaker of warm water they will generate electricity that you could use to make another beaker of water even warmer and the first beaker of water would get cooder. So energy would be spontaneously flowing from a cooler body to a warmer body. The 2nd law says this cannot happen.

    Show me where antennas is cloths can make power from IR? I have read about antennas tuned to radio frequencies that are used to very slowly charge cell phones or iPods but remember radio transmissions are coherent (low entropy). Crystal set radios also work from the small amount of power from their antennas, a tiny fraction of the 50,000 watts spewed out by a clear channel station. This has no relation to capturing useful energy from waste heat.

    Bob: So, it is impossible to filter out light of certain polarizations?

    RF: Polarized light is somewhat more ordered but far cry from being coherent. One usually needs a laser for that. They used polarized light to show that the antennas absorbed more energy when the electric vector (I think) was lined up with the long axis of the nanotubes that were tuned to that frequency. This is an interesting result showing that its the antennas that are absorbing the energy but that energy is just going into heating the array not into generating power. Maybe their research is a cover for development of radar absorbing material for the military?

    Bob: Consider an antenna in a room at 300K………

    Coherent light is perfectly ordered light (lowest entropy, all in phase, etc.). Yes, theoretically lasers could be used to transfer power via nanoantennas (if they ever find suitable diodes). In this case the entropy increase would be accounted for in the excess heat (non-coherent IR mostly) given off by the antennas. Coherent micro waves have been used to power a toy helicopter, albeit inefficiently. This is shown on YouTube somewhere. That is a far cry from using black body radiation.

  • Bob

    RF: This statement may be a clue to your problem. The mini Sterling engine works on a temperature difference. There is a warm end and a cool end. The nanoantenna system as described has NO cold end nor can there be a cold end with an antenna.

    Bob: Well of course it works on a temperature difference. Lets talk about warm human body IR emitted off the body, flowing through room temperature space and hitting an antenna. The photons ARE the hot end and the electrons in the metal ARE the cold end of the antenna and this IS a heat engine. A circuit CAN be a heat engine as well as any other machine if designed properly.

    You seem to believe the antenna will always instantaniously be in equilibrium with any IR that hits it. This is not logical or possible if you just compare the thermal time constant for the metal to warm up with the speed of the photon exciting an electron. Or the speed of the photon through the air getting to the antenna vs. the time it takes to warm up the air.

    For your interest, here is an MIT all silicon heat engine (converts heat to motion) less than one cubic micron. As I understand your argument, this should not be possible.

    http://nextbigfuture.com/2010/01/demo-of-all-si

    RF: They claim that if you put the antennas in a beaker of warm water they will generate electricity that you could use to make another beaker of water even warmer and the first beaker of water would get cooder.

    Bob: I have not read them saying that. Is that a quote or your projection of what they say?

    RF: Show me where antennas is cloths can make power from IR?

    Bob: This is a concept, not a product.

    RF: I have read about antennas tuned to radio frequencies that are used to very slowly charge cell phones or iPods but remember radio transmissions are coherent (low entropy). Crystal set radios also work from the small amount of power from their antennas, a tiny fraction of the 50,000 watts spewed out by a clear channel station. This has no relation to capturing useful energy from waste heat.

    Bob: The Cosmic background radiation is not coherent radiation. Nobody has a problem measuring that.
    Anyway, “waste heat” is a relative term. In may car, 70% of the energy liberated by oxidation of gasoline is waste heat. Not because thermodynamics says it must be 70%, because the engine design is crude.

    RF:This is an interesting result showing that its the antennas that are absorbing the energy but that energy is just going into heating the array not into generating power.

    Bob: It just generates heat because they don't have diodes in the antenna arrays yet. It proves the antennas work as predicted. At thius point they are only designed to soak up IR and make heat.

    RF:Yes, theoretically lasers could be used to transfer power via nanoantennas (if they ever find suitable diodes). In this case the entropy increase would be accounted for in the excess heat (non-coherent IR mostly) given off by the antennas.

    Bob: You said earlier that the antenna cannot support a temperature difference and thus cannot produce power. Yet you say a laser hitting the antenna can move the electrons. Your earlier objection about temperature differences should not change just because the photons are lined up. Their energy is the same. BTW, the microwave helicopter example was something like 54% efficient. A later project beamed 30KW one mile at 84%. That is high by any standards.

    http://www.mtt.org/awards/WCB%27s%20distinguish

    RF: That is a far cry from using black body radiation.

    Bob: The entire earth uses blackbody radiation.

    Anyway, I will be gone this weekend. Back Monday. If you are weary we can stop anytime. I do appreciate the debate as it makes me think. Thanks!

  • Ramsey Frist

    Bob: Well of course it works on a temperature difference……….

    RF: That is like saying that a Sterling engine itself can be its own cold end so 100 percent of the heat fed into it is converted to mechanical energy. The 2nd law does not allow that.

    An antenna is a closed system as is a Sterling engine. Energy can be exchanged between the system and its environment but not mass. Heat from highly ordered (low entropy) fuel flows through a Sterling engine and some free energy is extracted that can be used to do work (make more order, lower entropy, etc.). This MUST BE PAID FOR by an increase in entropy of the surroundings (gases of combustion and heat, mostly IR).

    Its the same with antennas. They can receive electromagnetic energy of a certain range of wavelengths and convert a portion into electrical energy that can perform work. This must be paid for by the antenna giving off longer wavelengths (such as high entropy IR) otherwise one can make a perpetual motion machine as I have described before.

    So, for photo antennas to work they must overcome at least two obstacles, diodes that work and a way to pass on entropy to their surroundings. There is virtually no hope for IR antennas to work unless you can somehow have them give off lower frequency wavelengths (radio?). With photo antennas designed for visible or near IR the problem is more with functioning diodes. As of yet there are no diodes that work at IR frequencies let alone higher frequencies.

    • Ramsey Frist

      Addendum: I got carried away in my analogy and included the fuel as part of the system for the Sterling example. I should have said that concentrated heat (low entropy) from the burning fuel flows into the hot end of the engine and high entropy IR is dispersed from the cold end. I guess I am used to explaining to students how living things “feed” on negative entropy.

  • Bob

    RF: So, for photo antennas to work they must overcome at least two obstacles, diodes that work and a way to pass on entropy to their surroundings. There is virtually no hope for IR antennas to work unless you can somehow have them give off lower frequency wavelengths (radio?). With photo antennas designed for visible or near IR the problem is more with functioning diodes. As of yet there are no diodes that work at IR frequencies let alone higher frequencies.

    Bob: As I understand your argunment, with visible light and near IR, if you had working diodes, the antenna would work because you are emitting longer IR to obey the 2nd law. With IR at arounf 10 microns it would not work unless you emitt even longer wavelengths.

    Isn't it funny that antennas do work with microwaves and they obviously obey the 2nd law by emitting
    radiation at SHORTER wavelengths in the IR as heat!

    Isn't it funny that numerous papers reported rectification at IR and even visible light. Sure, there are no off the shelf commercial diodes you can buy but your statement that “As of yet there are no diodes that work at IR frequencies let alone higher frequencies” seems a little too strong so I ask you are there papers and their authors all wrong?

    • Ramsey Frist

      Bob: Isn't it funny that antennas do work with microwaves…..

      RF: In the case of the microwave transmission we are taking about low entropy coherent radiation that is produced my a magnetron or whatever, not black body radiation. Out of phase photons randomly bombarding an antenna is another story.

      The same is true for the IR rectantennas. They were using laser light to test their diodes. Somewhere I noted one group was pleased with a one percent efficiency. That may or may not be within experimental error. Somewhere above you said that the workers used lasers because it was convenient. A heat lamp is much cheaper than a laser.

      Bob: Isn't it funny that numerous papers reported rectification at IR and even visible light.

      RF: I may have been a little strong. There is some evidence of charge separation resulting from absorbed light is biological systems. There is a lot of interest in getting biological photosystems to make electricity or release hydrogen. I have not thought out the thermodynamic implications but I am sure that IR release accounts for most of the gain in entropy.

      I gave you the example two adjacent rooms with a Sterling engine between them. With a functioning black body IR antenna and resistive space heater one room spontaneously gets hotter the other cooler and the engine becomes a perpetual motion machine. You tell me where my reasoning is wrong.

  • Bob

    RF: I gave you the example two adjacent rooms with a Sterling engine between them. With a functioning black body IR antenna and resistive space heater one room spontaneously gets hotter the other cooler and the engine becomes a perpetual motion machine. You tell me where my reasoning is wrong.

    Bob: I already said if it is truly equilibrium nothing wil lhappen. The problem is you keep equating complex non equilibrium dynamic situations as equilibrium. For example, a static equilibrium is not the same as a dynamic balance. You ignore the difference. Take an antenna outside at the air temperature. It may be in equilibrium with the local air but it may not be in equilibrium with the sky or the ground sources of IR. Or a roof or a road or any IR source different from the local air temp. A person is an IR source of about 200 W/m^2 irradiance. Go out on a cool evening with a FLIR camera and that person is a bright source of IR.
    If you had an efficient antenna ten meters away you should be able to collect measurable power on the order of a W/m^2. IR travels at the speed of light from its source, not by heating the air. It is not heat.
    Your strawman examples assume the only IR available is in complete balance with air, walls, floors
    as far as the rates of flux go. IN fact, rarley does this happen. In nature, things sitting in the same sunlight are at different temperatures depending on their emmisivity. Could you use two different kinds of rock at two temps to drive a Sterling engine. Yes. Suppose you paint one of those two rooms with high emissivity paint and the other with low? You have broken the equilibrium for at least a while. Maybe the same with antennas. At least if the antenna was connected to another outside the rooms at lower temp it might serve as a low potential path to radiate heat away from the whole system.

    • Ramsey Frist

      Bob: I already said if it is truly equilibrium nothing will happen……

      RF: But that is not what the INL people are claiming. They say ambient, non-coherent, IR (regardless of where it comes from) can be passively collected and used to perform work (decrease entropy) while the antennas are cooling their surroundings by sucking up IR. In the example with the adjacent rooms their magic antennas would be able to maintain a temperature difference between the rooms by pumping energy from one to the other. That is, they would keep the rooms out of equilibrium without expending energy. So, if you admit that the antennas cannot work under these conditions why would they be more likely to work if you have an outside source of IR even if it is of greater intensity?

      The two room example is the same as if you had two blocks of metal at the same temperature on a table in front of you and you pushed them together. You would not expect energy (heat in this case) to flow spontaneously from one to the other (decreasing entropy). On the other hand, if you put a hot block in contact with a cold one energy will spontaneously flow from one to the other until they are both at the same temperature. The second case is an entropy driven process as the heat has become more disperse and overall entropy has increased. To drive the reaction the other way (to decrease entropy) requires an outside source of energy.

      BTW. I thought physicists sometimes call IR radiant heat?

  • Bob

    RF: But that is not what the INL people are claiming. They say ambient, non-coherent, IR (regardless of where it comes from) can be passively collected and used to perform work (decrease entropy) while the antennas are cooling their surroundings by sucking up IR.

    Bob: You have to distinguish between what scientists say to reporters and how its gets written for the public. The public articles are not scientific papers. One hopes they are accutate but one has to consider that they are articels. The INL papers themselves only say the re-radiated IR is an underutilized source. That's certainly true. When Novack states in videos or interviews that the antennas can cool a room, it is you, not he, that is making the assumptions he means what you state in your examples. I assume he means the antennas are attached to walls at room temperature and something is going on to raise the temperature of the inside of the room like people, electroncs or whatever. The antennas simply absorb the IR from these hotter than room temperature sources and shunt it away keeping the room from rising above the wall temperature. I see no problem with this and nither should you. You could do the same with better walls anyway like adobe houses which keep houses withing a small temperature range as I understand them.

    RF: So, if you admit that the antennas cannot work under these conditions why would they be more likely to work if you have an outside source of IR even if it is of greater intensity?

    Bob: Because that is not equilibrium! Think about it. Take a FLIR outside at night and look around. If everything was in equilibrium you would see nothing!. You see temperature differences all over. These are all sources. And another thing, There are numerous papers in the IR field discussing IR antennas
    atached to recifying diodes ending up with actual currents used as signals. These are designed
    as sensors, not power production units but the principles are the same. They are not cryocooled, they sense IR from random sources in the environment, so called black body IR, people, machines, whatever. My point is that the only difference between sensing and energy generation is design. What you claim is impossible is being done now albeit with small scale sensing not power generation. IR is a big field and the INL folks are not lone quacks.

    RF: The second case is an entropy driven process as the heat has become more disperse and overall entropy has increased. To drive the reaction the other way (to decrease entropy) requires an outside source of energy.

    Bob: And what I am saying is that antennas could make that heat transfer faster than convection or conduction or make power to do work elsewhere.

    RF: BTW. I thought physicists sometimes call IR radiant heat?

    Radiant energy I believe. It causes heat when it interacts with matter. Otherwise it travels through space untill it hits something. As you know heat has units of energy and work. If I have an object in space at 300K it radiates that away. If I hit is with the same flux of 300K photons (loose language as photons do not actually have a temperature) it stays at 300K. If I hit is with a much greater flux of 300K photons it has to absorb more energy than it can release and its temperature must rise. Temperature is just a convenient measure of how much energy a body has.

    • Ramsey Frist

      Bob: When Novack states in videos or interviews that the antennas can cool a room, it is you, not he, that is making the assumptions he means what you state in your examples. I assume he means the antennas are attached to walls at room temperature and something is going on to raise the temperature of the inside of the room like people, electroncs or whatever. The antennas simply absorb the IR from these hotter than room temperature sources and shunt it away keeping the room from rising above the wall temperature.

      RF: Does that mean one can now take the electricity from the antennas in your hot room and use it to add heat to yet another even hotter room?

      If the antennas should work what difference does it make where the IR comes from or if there is a temperature gradient?

      BTW, I thought energy is measured in calories (I never got use to using joules). Temperature is defined as what one reads with a thermometer.

  • Bob

    RF: Does that mean one can now take the electricity from the antennas in your hot room and use it to add heat to yet another even hotter room?

    Bob: If there is a temperature gradient in one room and you make power with it, you can use that power in any other room regardless of temperature. Same as if I make that power with a Sterling engine using the same gradient. If I have a resistor in the hotter room sitting at the higher temperature and I run electricity through it, it generates heat at rate I^2 R and heats the room a little more. Surely, that breaks no laws. Who cares where the electricity comes from if it comes from outside. I think if you calculate the whole process, there will be no issue with entropy. It will rise.

    RF:If the antennas should work what difference does it make where the IR comes from or if there is a temperature gradient?

    Bob: It makes no difference where the IR comes from however if the antenna truly is in equilibrium, it will radiate as much IR as it takes in or in other words, the net flux around it is zero and it should produce no net power. A tenperature gradient means there is a net flux.

    RF: BTW, I thought energy is measured in calories (I never got use to using joules). Temperature is defined as what one reads with a thermometer.

    Bob: 1 calorie = 4.184 joules. Temperature is defined by the average thermal motion or kinetic energy of the molecules in a substance. In a thermometer, if the average kinetic energy is higher, the density is lower and the mercury expands registering a higher temperature.

    • Ramsey Frist

      Bob: It makes no difference where the IR comes from however if the antenna truly is in equilibrium, it will radiate as much IR as it takes in or in other words, the net flux around it is zero and it should produce no net power. A temperature gradient means there is a net flux.

      RF: If there rectenna system worked they would hardly ever be in equilibrium. As long as they had a load they would be scarfing up IR unless their surroundings got very cold. Sterling engines work on a gradient but exactly where is this gradient and flux you speak of in an antenna?

      Maybe these rectennas would work :) http://starwars.wikia.com/wiki/Rectenna

  • Bob

    RF: BTW, I thought energy is measured in calories (I never got use to using joules). Temperature is defined as what one reads with a thermometer.

    Bob: BTW, temperature is not defined in space. The cosmic background microwave radiation is 2.7K but that just corresponds to the peak temperature of a blackbody that would emit that radiation so in loose terms the temperature of the universe is about slightly above 2.7K.

  • Bob

    RF: If there rectenna system worked they would hardly ever be in equilibrium. As long as they had a load they would be scarfing up IR unless their surroundings got very cold. Sterling engines work on a gradient but exactly where is this gradient and flux you speak of in an antenna?

    Bob: Generally Sterling engines work off a gas or working fluid between the two temperatures. Think of the conduction electrons in the antenna as an electron gas. It is the fluid. At rest it is at the cold end. If it absorbs a lot of extra photons it becomes hot and moves creating current. After work is done it expends the waste heat as IR at some waveslengths somewhere. The gradient is the net flux at the antenna element where the electrons are available. If it averages zero the electrons feel no net force. If it is positive into the antenna the electrons feel a motive force and make current. If it is negative out of the antenna the photons in the antenna couple to the electrons and they move to help radiate the IR out of the antenna faster than convetion.

    • Ramsey Frist

      Finally, you are getting very close to a working system. For the antennas to work there must be a way to pass on lower entropy IR (to meet Carnot's rules) than it receives. I am just not sure there is any way for the rectennas as proposed to do that. Maybe you could come up with a functioning design.

  • Bob

    RF:Finally, you are getting very close to a working system.

    Bob: Thanks!

    RF:For the antennas to work there must be a way to pass on lower entropy IR (to meet Carnot's rules) than it receives. I am just not sure there is any way for the rectennas as proposed to do that. Maybe you could come up with a functioning design.

    Bob: Agreed they or rather the system as a whole rises in entropy. I am thinking through the entropy processes.

  • Bob

    Bob: Just to be clear I meant I agree for the antennas to work there must be a way to pass on lower entropy IR not that I am doubtful they can do that.

    • Ramsey Frist

      Now that we have been all around Robin Hood's barn please reconsider my initial setup. Lets put the antennas in a large perfectly insulated box or say a very big Dewar flask. Connect the output to a heater that is pasted to a copper block some distance away from the antennas. We could put other things in the flask as well, even a little ecosystem or a Sterling engine with its “hot” end against the block. Lets say initially everything in the flask is at 100 degrees C so the flask is flooded with IR reflecting off the walls, etc. Now I am betting that if you opened the flask after a few hours or a few days or years everything in the box will be at the same temperature and the Sterling engine will not have turned. Now, if the nanoantenna system worked they would keep pumping energy into the copper block keeping it warmer than anything else in the flask and keeping the engine going for perpetuity.

      Now, the antennas don't care where the IR is coming from. There may absorb more IR perpendicular to the plane of the antennas but there is no difference between the front or the back of the antennas. According to the INL people as long as IR is impinging on the antennas they will put out power. I think that means that if the antennas can work in a Dewar flask they will work on a hot roof or vice versa. I am betting they won't work in either case.

  • Bob

    RF: Now, if the nanoantenna system worked they would keep pumping energy into the copper block keeping it warmer than anything else in the flask and keeping the engine going for perpetuity.

    Bob: No, and no one makes such claims. Why do you keep insisting this will happen? I think you know better. However, one can set up an oscillating system that trades energy off between two states which will
    work for a while untill the small losses in each bounce degenerate the energy and everything equals out.

    Your strawman arguments always have a fixed, finite amount of energy rather than a continuios flux of new energy as my examples do.

    RF: Now, the antennas don't care where the IR is coming from. There may absorb more IR perpendicular to the plane of the antennas but there is no difference between the front or the back of the antennas. According to the INL people as long as IR is impinging on the antennas they will put out power.

    Bob: If you understand antennas you know there is a fairly large range of angles they will work. But what you are ignoring is what I stated before, that the total flux matters. If there is more flux impinging on the antenna than is exiting the antenna, all angles considered, it will absorb energy.

    RF: I think that means that if the antennas can work in a Dewar flask they will work on a hot roof or vice versa. I am betting they won't work in either case.

    Bob: Be serious. You explain why an antenna array will not work wit ha hot roof against a cold sky wheras a Sterling engine, or almost any conceivable heat engine will.

  • Bob

    RF:I am betting they won't work in either case.
    Bob:
    Attached is infromation about a past seminar by Dr. Glenn D. Boreman of University of Central Florida.
    Please tell me why all this work amounts to nothing useful and explain why the results the get are just illusions and misunderstandings since according to you, the second law forbids most of what they have seen.

    Dr. Glenn D. Boreman
    University of Central Florida
    Infrared Antennas
    November 06, 2008 11:00AM Engineering Board Room Fitzpatrick Hall

    Radiofrequency components such as antennas, transmission lines, phased arrays, frequency-selective surfaces, reflectarrays and meanderline waveplates are demonstrated in the infrared. Usual design methodologies apply, providing that IR material properties are used in the computations.
    We fabricate nanoscale antenna structures resonant at infrared (IR) frequencies using direct-write electron-beam lithography. Antennas facilitate electromagnetic coupling to sub-wavelength sized sensors (e.g., bolometers, Schottky diodes), with resulting spectral and polarization response determined by the dimensions and arrangement of the antenna arms. Along with single-element antennas, we have demonstrated both incoherent and coherent antenna arrays, with co-phased response verified by measurements of the angular reception patterns. In phased-array configurations, beam shifting and beam narrowing are noted, in agreement with classical antenna theory. Dual-dipole antennas can also be used to measure the magnitude of the spatial coherence of the incoming radiation, at the location of the two antennas.
    Frequency selective surfaces (FSS) are two-dimensional arrays of metallic antennas with subwavelength periodicity. Depending upon the geometry of the antenna arrangement, these have been demonstrated as spectral reflectance or transmittance filters in the IR and THz. They have also been configured as selective absorbers, to control the IR spectral emissivity of a surface by means of Kirchhoff’s law. One extension of the IR FSS concept is the reflectarray, which is a quasi-periodic array of antennas for which the phase shift on reflection depends on the local unit-cell geometry. Varying the antenna dimensions across the surface of an array can be used to produce a flat surface with optical focusing power. We have demonstrated these in the IR, at wavelengths as short as 1.5 micrometers. Another extension of FSS technology is the meanderline waveplate. These have been demonstrated in the 3-5 and 8-12 micrometer IR bands, and allow implementation of a quarter-wave, half-wave, or arbitrary retarder. Unlike the usual crystalline waveplates, the meanderline device has a thin aspect ratio and significant angular and spectral bandwidths.
    In the design of these devices, accounting for the spectral variation of the real and imaginary parts of the permittivity is crucial to obtain accurate agreement between numerical models and measured results. This is particularly important for thin (typically 100 nm) metallic films, for which inadequate tabular data are available in the literature. Material properties are measured as a function of frequency with an IR variable-angle spectroscopic ellipsometer, and then imported into full-wave electromagnetic models for design and analysis.

  • Ramsey Frist

    Bob: Be serious. You explain why an antenna array will not work wit ha hot roof against a cold sky wheras a Sterling engine, or almost any conceivable heat engine will.

    RF: And just how can an antenna distinguish between IR photons impinging on it in a Dewar flask and IR reaching it when it is between a hot roof and the sky? Would not that require something like a Maxwell demon? One can point the hot end of a Sterling engine at the roof and the cold end at the sky. Antennas have no ends.

    I have no trouble agreeing with Borman's work. Nanoantennas have been used as an IR source and as a way of focusing IR but this all requires energy and is in agreement with the 2nd law. Try to find one example of black body IR used to generate power via an antenna.

    Theoretically one should be able to use any temperature gradient such as between a hot roof and space to capture energy within the Carnot limits. What I am saying is that this cannot be done with rectennas alone. Something must be added to the system so that entropy increases to pay for the electricity which can be used to decrease entropy.

  • Bob

    Bob: Let's go back to the point I thought we were making progress on. This may illuminate some things. I shall then address your points above. I stated;

    “Think of the conduction electrons in the antenna as an electron gas. It is the fluid. At rest it is at the cold end. If it absorbs a lot of extra photons it becomes hot and moves creating current. After work is done it expends the waste heat as IR at some waveslengths somewhere. The gradient is the net flux at the antenna element where the electrons are available. If it averages zero the electrons feel no net force. If it is positive into the antenna the electrons feel a motive force and make current. If it is negative out of the antenna the photons in the antenna couple to the electrons and they move to help radiate the IR out of the antenna faster than convetion.”

    You responded:
    “Finally, you are getting very close to a working system. For the antennas to work there must be a way to pass on lower entropy IR (to meet Carnot's rules) than it receives. I am just not sure there is any way for the rectennas as proposed to do that. Maybe you could come up with a functioning design.”

    Ok. Lets address the entropy question. An IR photon comes in, we don't care from where, and hits the antenna. In general, the photon does not just hit the electron and ignore the lattice. This is in reality like a three body collision where the lattice as a whole is the third body. I believe in the general case this is important for momentum conservation. The photon is destroyed, it lo longer exists. The energy is absorbed by the lattice/electron system with most of the energy going to the electron and some small part going to the lattice. This is where entropy begins to be accounted for. Even lower frequency or longer wavelength phonons in the lattice which ultimately get released somewhere as longer IR.

    RF: And just how can an antenna distinguish between IR photons impinging on it in a Dewar flask and IR reaching it when it is between a hot roof and the sky? Would not that require something like a Maxwell demon?

    Bob: The same microscopic processes are going on in each case all the time. In the Dewar the total energy availanle is fixed and if there is any non-equilibrium to start with it will be smoothed out and things will get quiet. In the hot roof/cold sky there is a stronger non-equilibrium that is a gradient which can be used untill the roof cools to the sky temerature. Then things are quiet.

    RF: One can point the hot end of a Sterling engine at the roof and the cold end at the sky. Antennas have no ends.

    Bob: The Sterling engine works because there is a gas or fluid composed of somethings like Avagadro's number of particles. Each atom absorbs energy from the hot source through several possible mechanisms including IR radiation. That hot atom has a high kinetic energy which we call temperature, it does work and in the process it gives up its energy to the cold source.

    Think of the antenna as a solid state Sterling engine. The gas is conduction electrons, the hot source
    are the IR photons and the cold source is the environmental temperature of the antenna or the state of the lattice the electrons are at rest in. The work it does is current flow. The waste heat are the lattice phonons and or heat genrated by current flow.

    Now, this raises seveal interesting questions. How do we compute the Carot efficiency? Clearly if we assume T high is just the photon temperature and T low is the lattice temperature we are led astray.
    Otherwise, how are radio and microwave antennas able to convert, at room temperature, photons much much lower in equivalent temperature at near 100%. This is not an issue of coherence vs. non coherence for in either case we still have the same Carnot equation whatever it is. The answer is that the energy of the photon gives the electron very high kinetic energy and an effective temperature far greater than the latttice. This is why the efficiency of antennas are near one. So, T high and T low are the temperatures of the electrons before and after the photon is absorbed. This is why almost any non-equilibrium will be sensed by an antenna.

    RF: I have no trouble agreeing with Borman's work. Nanoantennas have been used as an IR source and as a way of focusing IR but this all requires energy and is in agreement with the 2nd law. Try to find one example of black body IR used to generate power via an antenna.

    Bob: Borman does not add energy to sense/rectify IR from enviromental sources. One big aspect of his work is IR detectors which means they are detecting random IR in the environment or in other words, black body IR from sorces. Sure, since he is not making power modules (yet) he may amplify his signal but the point is the IR gets rectified before that. If it didn't work you could not make IR imagers.

    BTW, Borman works closely with Novack and INL even though he is not an author on their paper.

    RF: Theoretically one should be able to use any temperature gradient such as between a hot roof and space to capture energy within the Carnot limits. What I am saying is that this cannot be done with rectennas alone. Something must be added to the system so that entropy increases to pay for the electricity which can be used to decrease entropy.

    Bob: I hope I have explained above how entropy is accounted for.

    • Ramsey Frist

      RF: You make a great salesperson. For a few minutes you almost had be convinced that the antennas might work.

      Bob: This is where entropy begins to be accounted for. Even lower frequency or longer wavelength phonons in the lattice which ultimately get released somewhere as longer IR.

      RF: So your saying the antennas would automatically absorb IR, release microwaves or radio waves, and produce electrical energy? That means that one could set up a bank of antennas in a house powered by IR radiating from the walls and use the electricity to cook with or whatever. At the same time the house would be kept cooler than its surroundings because the heat moving into the house to warm the walls would provide the energy to pump itself out of the house as microwaves or radio waves (the walls of the house would be no barrier to the microwaves). To boot, in the winter one could move the antennas outside and use them to heat the house.

      If this works I will be the first to sign up for free heating and air conditioning.

  • Bob

    RF: You make a great salesperson. For a few minutes you almost had be convinced that the antennas might work.

    Bob: I thought hard trying to make you see there are reasonable mechanisms to address your concerns about entropy. I have found yet more academic papers suggesting IR as a source of energy for antennas to be used with. To prove that the concept of thermal energy scavenging of environmental IR is not a pipe dream, the following abstract shows a microscopic silicon based MEMS heat engine that works on as little as 1.5C thermal gradiants which is far less than hot roof/cold air.

    “Resonant operation and cycle work from a MEMS-based micro-heat engine”
    L. W. Weiss1
    (1) Louisiana Tech University, Institute for Micromanufacturing, 911 Hergot Ave, Ruston, LA 71272, USA
    Received: 14 June 2008 Accepted: 3 October 2008 Published online: 31 October 2008

    Abstract The documentation of a new engine thermodynamic cycle on the micro-scale is presented. This new cycle is the result of resonant operation and cycle work production from a MEMS-based micro-heat engine. The engine is constructed of two thin membranes surrounding a cavity filled with working fluid. This new thermodynamic cycle is shown to include nearly constant volume pressure increase, expansion, heat rejection, and compression components. A thermal switch is integrated with the micro-engine to control heat rejection. The micro-engine is shown to produce up to 6.7 μW of cyclic mechanical power when operated on this cycle. Micro-engine natural frequency is shown to vary from 90 to 140 Hz. The Micro-engine is shown to operate across a low temperature gradient of 1.5°C. “

    So basically, we have a virtually solid object that sits in a plane surface absorbing IR and making power. In this case its mechanical power but that could be converted, as others do, to electrical power. The only difference between the antenna and this is that this uses a physical working fluid in a very small cavity vs. an electron gas in the metal. Reduce this engine down to its theoretically most simple construction and you will invent the antenna.

    RF: So your saying the antennas would automatically absorb IR, release microwaves or radio waves, and produce electrical energy?

    Bob: Only with a thermal gradiant or radiative net flux and only with the sum of all the types of energy produced being higher in entropy that the source.

    RF: That means that one could set up a bank of antennas in a house powered by IR radiating from the walls and use the electricity to cook with or whatever.

    Bob: I have shown you that an antenna functions like a heat engine and that silicon based micro heat engines exist scavaging temperature differences as small as 1.5C (basically stray blackbody IR). So my response to your continued tests is to ask yourself for any concievable scenario, “how will a panel of planar micro heat engines that take stray heat and make electrical power work in this situation?”. However they act, the antennas will do the same but likely more efficiently because they couple hot source to working fluid more efficently. It's really that straightforward.

    • Ramsey Frist

      Where in these nanoantennas is the intelligent demon that tells the difference between an IR photon coming from a cool wall or one from the sun? Why would nanoantennas only work if they are cooler than their surroundings?

  • Bob

    RF:Where in these nanoantennas is the intelligent demon that tells the difference between an IR photon coming from a cool wall or one from the sun? Why would nanoantennas only work if they are cooler than their surroundings?

    Bob: Where in the gas or fluid of a Sterling engine or any heat engine is the demon that tells an atom that a photon /phonon it is going to absorb is from the hot source or from the cold source?

    RF: Why would nanoantennas only work if they are cooler than their surroundings?

    Bob: They “work” all the time. If the net flux at the antenna in ingoing the antenna produces net power. If it is outgoing the antenna radiates heat to a cooler environment. If it is in equilibruim the rates going in and out are the same and no net power is produced or radiation released.

    • Ramsey Frist

      I see no problem with micro heat engines working with a small temperature gradient.

      Your electron fluid and “cooler” matrix is a very good description of how antennas in general work. Coherent radiation from a distant source is absorbed, energy trapped, and some heat and less coherent radiation is given off to the cooler environment. I accept your heat engine analogy.

      On the other hand, if the nanoantennas work with black body IR when they are in cool surroundings with flux from the sun its not clear why they would not work to extract heat from an insulated house or if they were put in an oven. We both agree the latter cannot happen but why not?

  • Bob

    RF:Your electron fluid and “cooler” matrix is a very good description of how antennas in general work. Coherent radiation from a distant source is absorbed, energy trapped, and some heat and less coherent radiation is given off to the cooler environment. I accept your heat engine analogy.

    Bob; Thanks. I really appreciated the lively debate.

    RF: On the other hand, if the nanoantennas work with black body IR when they are in cool surroundings with flux from the sun its not clear why they would not work to extract heat from an insulated house or if they were put in an oven. We both agree the latter cannot happen but why not?

    Bob: We agree when the antenna is at the temperature of the inside of the house or oven no net power will be produced. If the antenna is at the house or oven temperature to start with no net power is produced because they are already in equilibruim with the only source available. They are “working” but with zero percent efficiency.

    But here is how I think they would be used;

    Take a room in the house at 70F. Nothing happens and all is in equilibrium. Take a strong heat lamp and aim it at the walls where the antennas are arrayed. They see a “distant” source much hotter than the air/walls they are in and start to work. Of course, they don't work 100% and some IR has to go into the walls, air, lattice atoms of the antennas ect. The temperature rises above 70F. They ONLY thing they can do is to keep the room from rising as fast as if they were not there. They can NEVER lower the temperature of the room below 70F. They cannot even keep it there (thus obeying the Second Law).

    From a purley practical point of view then what good are they and how can they be claimed as “cooling” devices? If the temprature rises at a rate of 10F/hour instead of 30F per hour then in a practical sense (but NOT in a thermodynamic sense) they have kept the room “cool”. “Cooling” was probably a poor word to use and they should instead claim it helps “regulate” the heat.

    In the oven, let the oven start at room temperature and rise to a hot temperature. At first there is no equilibrium as the antennas see a hot source but the air is not that hot yet so they work for a while. Some of the IR that would have gone into heating the antenna lattice is converted to power but not enought to keep the lattice from rising to the hot air temperature. Eventually the antenna gets so hot it sees not much difference if any from the source and stops working.

    The bottom line is that they work to the extent there is no equilibrium and they stop working when there is equilibrium meaning the lattice is in equilibruim with the source as I see it.

    • Ramsey Frist

      I don't think the proposed nanoantennas will be that smart but if you can find an example of a rectenna that works when one shines a heat lamp on it I will be a believer.

  • Bob

    I

    RF: I don't think the proposed nanoantennas will be that smart but if you can find an example of a rectenna that works when one shines a heat lamp on it I will be a believer.

    Bob: Well, I think its not the antennas that are so smart but nature knows how to keep things in balance.
    The paper abstract below is one example of how the antennas are characterized in the lab. They heat the device on a hotplate and measure its emissions which by Kirchoff's laws are equal to its absorption characteristics so this is like using a heat lamp but is an equivalent but more convenient lab setup. The Novack paper does the same (it seems the Boreman group did some of the measurments for the INL).

    What you (and I) really want to see is the final product that produces power from IR. Glimpses of that future ability are in the literature in the form of small functioning test rectennas designed for broadband IR. I have seen at least one paper which in addition to the typical laser source used for testing did also use a monochomatic but otherwise conventional (i.e. non coherent, non laser) source and the antenna/diode rectenna still worked- produced a current.

    Infrared Frequency Selective Surface Based on
    Circuit-Analog Square Loop Design
    Brian Monacelli, Student Member, IEEE, Jonothan B. Pryor, Member, IEEE, Ben A. Munk, Life Fellow, IEEE,
    Dale Kotter, and Glenn D. Boreman, Member, IEEE
    Abstract—A frequency selective surface (FSS) was designed to
    have a resonant spectral signature in the infrared. The lithographically
    composed, layered structure of this infrared FSS yields a resonant
    response in absorption to infrared radiation at a wavelength
    determined by its FSS element structure and the structure of its
    substrate layers. The infrared spectral characteristics of this surface
    are studied via Fourier transform infrared spectroscopy and
    spectral radiometry in the 3 to 15 m region of the spectrum. The
    design is based on circuit-analog resonant behavior of square loop
    conducting elements.

  • Bob

    RF: I don't think the proposed nanoantennas will be that smart but if you can find an example of a rectenna that works when one shines a heat lamp on it I will be a believer.

    Bob: This is the paper that uses a quartz lamp. It's in the optical range but proves the point.

    “Investigation of resonance light absorption and rectification by subnanostructures”

    Guang H. Lin, Reyimjan Abdu, and John OM. Bockris
    Chemistry Department, Texas A&M University, College Station, Texas 77843

    http://jap.aip.org/japiau/v80/i1/p565_s1

    • Ramsey Frist

      If there antennas worked in 1996 one would think there would have been more progress would have been made by now. If the diodes work at such low voltages why bother with the antennas? Just paint them black.

      • Bob

        I think the diodes would not respond to the heat converted to random thermal motion of the atoms as well as they would the alternating current from the antenna's. Thermocouples that make voltage from a temperature difference are used in special cases but are very inefficient and costly.

        As far as progress goes sometimes the simple direct ideas are the hardest to make work. Fusion energy was thought to be easy when thet first started to work on it in the 1950's. The only point of this work was to show they solved the “cheap printing of a massive amount of antenna's” problem but not the complete problem with rectification.

  • Bob

    I think the diodes would not respond to the heat converted to random thermal motion of the atoms as well as they would the alternating current from the antenna's. Thermocouples that make voltage from a temperature difference are used in special cases but are very inefficient and costly.

    As far as progress goes sometimes the simple direct ideas are the hardest to make work. Fusion energy was thought to be easy when thet first started to work on it in the 1950's. The only point of this work was to show they solved the “cheap printing of a massive amount of antenna's” problem but not the complete problem with rectification.

  • Reggie

    Ramsey, the antennas, nanoscale or otherwise, do not reduce any entropy or destroy any energy. Antennas simply transform and move energy, causing an increase in the entropy of the electrical load placed on the system. The electrical load subsequently either stores or immediately re-radiates the energy as heat, light, RF, sound or whatever else back out into the universe.

    For an energy transfer to occur there does not need to be a downward gradient in total energy from the source to the sink. There only needs to be a downward gradient of the specific form of energy being transferred, which in this case would be infrared light at specific wavelengths.

    After sunset, there may still be objects in the vicinity of the solar collector which had absorbed heat during the day and which would continue to radiate for some time. Perhaps the very building the collector was mounted on would even radiate some IR light into the collector from behind.

    During the day, the collector is cooler than the sun, so no problem with a gradient. At night, the collector array would tend to cool off sooner than the building it is mounted on, so there would still be a gradient of heat into the collector.

    “People who say it cannot be done should not interrupt those who are doing it.”

  • Missoula

    This project is ridiculous based on the infrared solar panels. promise not working because the radiant head around is extremely low flow but huge amount. Try use it for small devices. unless you need to bombard the semiconductor with photons. For those who think is possible or why is not better do not ask to much because you will disappointed. remember:”the answer sometimes is so simple but peoples mind blowing thinking the wrong way”.

  • Arkresearch

    The proposer of this technology was HECTOR D PEREZ  from ARK RESEARCH  before 2002 ,and uses the DIODE PLUG  design within nanoantena micromilimetric arrays & LC tanks VECTORING DC power to a common DC buss from CARBON based nanodiodes .