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Physicists Build Circuit That Generates Clean, Limitless Power from Graphene

148 points by piercebot 6y ago

GRBurst 6y ago
Also https://phys.org/news/2020-10-physicists-circuit-limitless-power-graphene.html https://phys.org/news/2020-10-physicists-circuit-limitless-p... from here https://news.ycombinator.com/item?id=24665381 https://news.ycombinator.com/item?id=24665381
Jugurtha 6y ago
What does 'limitless' mean, physically?
- gilrain 6y ago
  'bullshit'
- Synaesthesia 6y ago
  I think it's going to be able to essentially deliver a very small current virtually indefinitely.
  - simias 6y ago
    That's how I understand it as well. It harvest the brownian motion of atoms in graphene. I definitely don't know enough about this subject to judge the plausibility of the claim but "graphene" and "limitless power" in the same headline does trigger a few red flags.
    - IgorPartola 6y ago
      You’ll still need a source of heat. This is a power converter not a source of free energy.
      - motoboi 6y ago
        But that means the graphene sheet need to be hotter than the surroundings? Or is this just converting heat from the air and infrared radiation into electric energy?
      - jack_riminton 6y ago
        So essentially its converting energy from the sun, via latent heat in the atmosphere into energy Could also use geothermal heat I guess
    - yourapostasy 6y ago
      I can't find the actual electrical power generated by the prototype circuit in the press releases, but it sounds like in the mA power range? It is "limitless" as long as the graphene mechanically survives (wonder how long that buckling will take to compromise the graphene) and there is some kind of minimum temperature maintained for the given required amount of electrical power output desired. Definitely not "free energy", but always good to reach further down into the physical realm in Feynman's "Plenty of Room at the Bottom" sense. I'm rooting around for alternative sources of the paper without success, but for those who have read it, what kind of graphene did they use (monolayer, CVD, GO, rGO, etc.)? I suspect that will somewhat throttle the manufacturing supply chain. Batteries are the least interesting application to me. This brings "sensor dust" out of solid fantasy into the realm of possibility in the far future; at first it will be "sensor clods", but let it follow the same evolutionary Shockley-to-ARM development path, and let's see where it goes. Permanently implanted medical chips to measure the blood, nervous and other internal medicine metrics we want to get our hands on might be more miniaturized; need to figure out how to extract out the incredibly weak signal.
      - MauranKilom 6y ago
        https://arxiv.org/abs/2002.09947 https://arxiv.org/abs/2002.09947
- cowpig 6y ago
  If I'm understanding the article correctly, a very tiny piece of graphene can pick up a very tiny amount of energy from the random jiggles at the atomic scale. Presumably, those jiggles are always going to be there, unless somehow earth becomes a cold, dead place. So imagine the solar panel on your calculator didn't need light, just a temperature above absolute zero.
  - deleted 6y ago
    [deleted]
  - gus_massa 6y ago
    This is exactly what the press release say, but this is impossible due the the Second Law of Thermodynamics. So (select at least one) 1) The press release is wrong 2) The research article is wrong 3) The Second Law of thermodynamics is wrong. [As a fast explanation, if the grapheme membrane and the lamp in the animation are at the same temperature, then the electrons in the lamp will get an equivalent amount of random jiggles and will counter the effect described in the article. (There may be also a similar problem with the diodes, capacitor, etc.)]
aduitsis 6y ago
Naive question, wouldn't this (converting Brownian motion into electricity) violate the 2nd law of thermodynamics? (edit, this is explicitly addressed further in the article: That's an important distinction, said Thibado, because a temperature difference between the graphene and circuit, in a circuit producing power, would contradict the second law of thermodynamics. "This means that the second law of thermodynamics is not violated, nor is there any need to argue that 'Maxwell's Demon' is separating hot and cold electrons," Thibado said.)
- jl2718 6y ago
  This sounds like a mangled explanation. It seems to me, somewhat naively, that the resonator must be held at a higher temperature than the rest of the circuit to produce work on the load.
  - aduitsis 6y ago
    I think some minuscule amount of energy is taken from the thermal bath (the environment is considered a thermal bath - you can take heat from it and it's so big its temperature won't budge), converted into electricity and then back to heat in the load resistor. They all remain in the same temperature if I'm not gravely mistaken.
- deleted 6y ago
  [deleted]
xt00 6y ago
It’s more like “limitless power from heat transferred into graphene from an external power source”. So it’s a special type of a thermo electric generator basically.
- ssivark 6y ago
  Thank you; awful title.
- ArtWomb 6y ago
  Only in the load resistor. Electron flux in the graphene membrane appears to be solely due to geometry. This curvature does not necessarily need to be buckled via heat energy. It could be mechanical or electrical, if I understand things correctly... More detail in this video clip with UArk's Paul Thibado: https://www.youtube.com/watch?v=wrleMqm3HiU https://www.youtube.com/watch?v=wrleMqm3HiU I think what this research opens up is the possibility of "optimal" harvesting. There is some resonant frequency, some circuit configuration yet to be discovered that is perhaps self-sustaining. They've chosen "stochastic thermodynamical" circuits because its low hanging fruit. But it seems really exciting to me. Almost like a third class of energy production after solar and hydrogen (where 99% of research funds are allocated). Ocean wave energy harvesting perhaps? In any case, congrats to the researchers on their painstaking hard work ;) Fluctuation-induced current from freestanding graphene: toward nanoscale energy harvesting https://arxiv.org/abs/2002.09947 https://arxiv.org/abs/2002.09947
  - IgorPartola 6y ago
    This does sound promising. Is it possible to run this process in reverse a la a heat pump to create an AC with no moving parts? Or is this purely a one way process?
    - arcticbull 6y ago
      Peltier coolers are probably in line with what you're suggesting, but they're not super efficient.
vitus 6y ago
> In the 1950s, physicist Léon Brillouin published a landmark paper refuting the idea that adding a single diode, a one-way electrical gate, to a circuit is the solution to harvesting energy from Brownian motion. Knowing this, Thibado’s group built their circuit with two diodes for converting AC into a direct current (DC). So, they built a full-wave rectifier (albeit with only 2 instead of, say, 4 diodes)? Pretty neat to see electrical engineering fundamentals at work. (also, for any who wanted specifics: article is at https://journals.aps.org/pre/abstract/10.1103/PhysRevE.102.042101 https://journals.aps.org/pre/abstract/10.1103/PhysRevE.102.0... ; abstract contains a couple of circuit diagrams) edit: updated link, thanks for pointing that out
- yourapostasy 6y ago
  Remove the semicolon at the end of the above link to get to the actual journal paper; paper is behind the APS paywall. Working link for the lazy: https://journals.aps.org/pre/abstract/10.1103/PhysRevE.102.042101 https://journals.aps.org/pre/abstract/10.1103/PhysRevE.102.0...
nayuki 6y ago
Is this based on the physics of the Seebeck effect to generate a voltage from a temperature difference? https://en.wikipedia.org/wiki/Thermoelectric_effect#Seebeck_effect https://en.wikipedia.org/wiki/Thermoelectric_effect#Seebeck_...
- deleted 6y ago
  [deleted]
kwhitefoot 6y ago
If this is representative of press releases from universities it's no wonder that people can't tell the difference between free energy scams and real physics. Sounds like nonsense to me but the article is so badly written that it's hard to tell. In fact it is hard to be sure whether they have actually created a prototype or merely simulated it.
- tgsovlerkhgsel 6y ago
  > If this is representative of press releases from universities If you want reporting that accurately represent science, in my experience, the university press releases are even worse than the worst mainstream shit-tier media.
  - gspr 6y ago
    It's super sad. My boss was once at the center of one of these big press release splashes at the university I worked. She said it was almost more of a burden than a boon, because the attention it attracted was almost all of the wrong kind. And among the right kind of people, she had to spend time and effort excusing the embarassing and ridiculous press release. I wonder if universities understand that they're sometimes harming their own people with these things.
  - barney54 6y ago
    The incentives for the PR team is to make news. They don’t have to spend a ton of time cleaning up the mess of misleading press releases.
    - gus_massa 6y ago
      At some point it tarnish the reputation of the university. If your university get famous for sending ridiculous press releases, I hope that eventually the journalist will notice and just forward them to The Onion.
      - raziel2701 6y ago
tsimionescu 6y ago
> The idea of harvesting energy from graphene is controversial because it refutes physicist Richard Feynman’s well-known assertion that the thermal motion of atoms, known as Brownian motion, cannot do work. Thibado’s team found that at room temperature the thermal motion of graphene does in fact induce an alternating current (AC) in a circuit, an achievement thought to be impossible. So it sounds like, if this really works, it may have some impact on our general understanding of thermodynamics or the properties of Brownian motion?
- gus_massa 6y ago
  If it works as described in the press release, this is a direct trip to Stockholm to pick the Nobel Prize. I can't read the research paper now. My guess is that there is a temperature difference between the grapheme and the resistor. In that case it's a normal experiment, perhaps with some tweak, but not a groundbreaking experiment. The power generated by the device is tiny (not "unlimited"), and there are a lot of similar devices. Sometimes the experiment is interesting in some niche (this experiment is related to tunnel microscopy) but this is totally overhyped.
  - Animats 6y ago
    If it works as described in the press release, this is a direct trip to Stockholm to pick the Nobel Prize. There are too many PR announcements like that in the nanotechnology and battery areas. It's either Nobel Prize material or nothing, and you can't tell from the article. No power numbers. Are they talking about generating a picowatt or something like that? Somebody like EVworld should publish "1, 5 and 10 years ago today in energy announcements".
    - gus_massa 6y ago
      Most press release about batteries claim a x2 improvement in 5 years or something like that. If they were true perhaps you can get a Nobel, but you must wait in the queue for a few years. If you break the Second Law you can skip the queue and even the voting. > No power numbers. Are they talking about generating a picowatt or something like that? The figures in the research article claims ~1pW. I still can't get the research paper, but reading the information that is available, and some enlightening discussions in HN I guess they measured a ~1pW exchange of heat in the other side of the device (the "lamp" in the animation). But it is ~1pW in one direction and exactly the same amount in the other direction. There is no net energy flux or "useful" energy. This may be an useful experimental result in the research branch they are working, but not "Limitless Power".
zaroth 6y ago
So apparently this is the “small device eliminates need for AC” that I see advertised everywhere! </s> But in all seriousness, it seems this converts ambient heat (not a heat differential) directly into electricity. Therefore it must necessarily cool its surroundings by the equivalent energy extracted? So it’s a kind of air conditioner which doesn’t use electricity to move heat but rather converts heat directly to electricity? I thought we “knew” this was impossible...
- philplckthun 6y ago
  > “People may think that current flowing in a resistor causes it to heat up, but the Brownian current does not. In fact, if no current was flowing, the resistor would cool down,” Thibado explained. “What we did was reroute the current in the circuit and transform it into something useful.” Based on this I understood that it'd indeed cool down and create a heat gradient if it wasn't doing any work, but the difference it'd create is instead used to induce a current, which means it probably wouldn't cool down as long as that potential is used in this way instead (?)
- Mountain_Skies 6y ago
  If it works, it'd be a great cooler for electronics that could put back into the circuit some of the electricity that had been turned into heat. CPU and GPU coolers could become built into the structure of the ICs themselves.
bencollier49 6y ago
So how much energy would you harvest by using these en masse to reduce the temperature of the earth by around 2.5 degrees centigrade? (I appreciate this is highly unlikely to be possible).
kossTKR 6y ago
Can this be scaled up to provide power that isn't just a gimmick in the grand scheme of things?
r-bryan 6y ago
Without getting all quantum about it, it seems to work by configuring the graphene as one electrode (or both) of a capacitor. As the graphene flaps in the breeze (actually Brownian motion, I assume), the changing geometry will change the capacitance. If there is a charge on the cap, then the voltage would flap too, inversely (Q = CV). A changing voltage would tend to push about a current (i.e. charge motion). If their diodes somehow have a negligible forward voltage drop, then brief moments of higher voltage on the flappy cap would push increments of charge onto the storage cap (the one to the right of the diodes) until the storage cap voltage rose to equal the peak flappy voltage (minus the diode voltage drop). When the storage capacitance is greater than the flappy graphene capacitance, the stored energy will be greater than the tiny increments (energy = 1/2 CV^2). Then every so often the storage cap could be switched to drive some load. So why would there be a charge in the flappy capacitor? Well, a bias voltage is applied by this battery in the circuit. Ahem, before invoking any principles of thermodynamics, I'd like to see some detailed measurements, or even careful theory, of the current out of the battery and back into the battery, particularly w.r.t. the instantaneous voltages (P = VI), to prove that the time-average power delivered by the battery is precisely zero, or at least far lower than that putatively transferred to the load (light bulb in the animation). Otherwise it's behold, we found a high-resistance path for our battery to run a light bulb. There is some precedent for semiconductor thermal magic in the Peltier junction. It makes one end colder and the other end hotter by applying electric watts to it, with no moving parts aside from the electrons and holes recombining, or something. But nobody sees thermodynamics being violated or extended there. But here the magic is to take away thermal energy from one place, the flappy graphene (thereby cooling it) and moving the energy to the light bulb (thereby heating it). It seems you could then use any old heat engine to extract work by letting the heat flow from the resulting hotter place back to the colder place, getting "limitless power" for free from your perpetual motion machine. Conceivably it's a sort of heat pump that gets some multiplier above the battery power. But I think the burden of proof is on the Arkansas folks to explain how this can be. If I had more energy (no pun intended, really) right now I'd try to find the paper that the press release is based on, to see if there's a little more truth there. Meanwhile, I doubt it.
- MauranKilom 6y ago
  > Otherwise it's behold, we found a high-resistance path for our battery to run a light bulb. It's like a nano Rube Goldberg! Paper is here btw: https://arxiv.org/abs/2002.09947 https://arxiv.org/abs/2002.09947
sradman 6y ago
The abstract of the paper Fluctuation-induced current from freestanding graphene [1]: > At room temperature, micron-sized sheets of freestanding graphene are in constant motion, even in the presence of an applied bias voltage. We quantify the out-of-plane movement by collecting the displacement current using a nearby small-area metal electrode and present an Ito-Langevin model for the motion coupled to a circuit containing diodes. Numerical simulations show that the system reaches thermal equilibrium and the average rates of heat and work provided by stochastic thermodynamics tend quickly to zero. However, there is power dissipated by the load resistor, and its time average is exactly equal to the power supplied by the thermal bath. The exact power formula is similar to Nyquist's noise power formula, except that the rate of change of diode resistance significantly boosts the output power, and the movement of the graphene shifts the power spectrum to lower frequencies. We have calculated the equilibrium average of the power by asymptotic and numerical methods. Excellent agreement is found between experiment and theory. [1] https://journals.aps.org/pre/abstract/10.1103/PhysRevE.102.042101 https://journals.aps.org/pre/abstract/10.1103/PhysRevE.102.0...
- mannykannot 6y ago
  "However, there is power dissipated by the load resistor, and its time average is exactly equal to the power supplied by the thermal bath." As the "thermal bath" is supplying power, this seems consistent with it being a Carnot-equivalent heat engine. There is certainly nothing in physics that prevents the extraction of energy from an environment in which the temperature fluctuates - devices that do so to keep mechanical clocks running indefinitely have been around for some time. http://atmosadam.com/howitworks.html http://atmosadam.com/howitworks.html
  - gus_massa 6y ago
    The clock in your link uses the temperature fluctuations, for example if it hot during the day and cool during the night. So you can have a flux of heat from the hot part to the cold part, and extract a small part as useful energy. If we take the press release at face value, in this device there is no difference of temperature. So if the Second Law of Thermodynamics is correct it is not possible to extract some useful energy to do something interesting, like turning on the lamp in the animation.
gus_massa 6y ago
Ignoring the horrible horrible horrible title ... This can only work if there is a temperature difference between the grapheme membrane and the load resistor (the lamp in the animations). Other wise, it breaks the Second Law of Thermodynamics. The problem is not that it breaks some remark from Feynman, the problem is that if there is no temperature difference, it breaks the Second Law of Thermodynamics and in particular an example in an explanation of Feynman.
- ag56 6y ago
  Doesn’t the article explicitly say that is not the case? > Though the thermal environment is performing work on the load resistor, the graphene and circuit are at the same temperature and heat does not flow between the two. I’m not a physicist or even an educated layman, can you explain your comment more?
  - gus_massa 6y ago
    I read that part a few times, but it makes no sence. I prefer another quote > What we did was reroute the current in the circuit and transform it into something useful. Let's suppose that they get some "useful" energy to turn on the lamp like in the animation or power a small device. Let's suppose that you use it to power a laser and send a beam that heat some object far away. As a side effect, you are extracting energy from the device with the graphene in the lab so it will get cooler. So the net effect is that the device in the lab gets cooler and the object far away get hotter. So you have a flux of heat. But if the other object is hotter, you have a lux of heat from in the wrong direction, that is impossible according to the Second Law. There are a million ways to rewrite this https://en.wikipedia.org/wiki/Second_law_of_thermodynamics https://en.wikipedia.org/wiki/Second_law_of_thermodynamics in more abstract or more concrete ways. With some oversimplifications, another is that you need at least two heat baths and the efficiency of the device to transform heat from the "hot" bath to of "useful" energy can be calculate using the temperatures of the baths. When the difference of temperature is zero, the efficiency is zero and the device can produce no "useful" energy. Or in other words, with only one heath bath, you can produce no "useful" energy.
sandworm101 6y ago
So it converts heat into work without a temperature gradient? That is the real revolution. I wonder if this could scale into a cooling solution for chips.
itsshreyarora 6y ago
I read the words "limitless power" and assumed it is crap. In case it it not, please reply to this comment, and I will give the article a read. There is no reason for you to do this, but thanks in advance, kind strangers.
- wtracy 6y ago
  The article is indeed garbage. It smells like there's actually some interesting research being done here using graphene to extract energy from the ambient environment (possibly harvesting the work done as the graphene expands during hearing?) but the press release was written by someone who does not understand the subject at all.
wolfi1 6y ago
this is the doi of the paper: https://doi.org/10.1103/PhysRevE.102.042101 https://doi.org/10.1103/PhysRevE.102.042101
andi999 6y ago
If the title of this post were true, the paper would have been published in nature instead.
- jostmey 6y ago
  While I share your disappointment in the quality of the press release, Nature is by no means the bar for measuring significance. I've been both accepted and rejected by Nature, I've seen colleagues accepted and rejected by Nature, and I've found results published outside of Nature, Cell, Science more reproducible!
  - andi999 6y ago
    I fully agree. But I still think if you could show violation of 2nd maw of thermodynamics and potentially solving all of human energy needs, I believe you would submit it to nature (or science). At least as signaling for getting funding for your trillion dollar startup commercializing the result.
stephc_int13 6y ago
Isn't it some kind of antenna? I might be completely wrong here, but I don't see that much of a difference, antennas are also "harvesting" power in some ways.

148 points by piercebot 6y ago

Also https://phys.org/news/2020-10-physicists-circuit-limitless-power-graphene.html https://phys.org/news/2020-10-physicists-circuit-limitless-p... from here https://news.ycombinator.com/item?id=24665381 https://news.ycombinator.com/item?id=24665381

Jugurtha 6y ago

What does 'limitless' mean, physically?

gilrain 6y ago
'bullshit'
Synaesthesia 6y ago
I think it's going to be able to essentially deliver a very small current virtually indefinitely.
- simias 6y ago
  That's how I understand it as well. It harvest the brownian motion of atoms in graphene. I definitely don't know enough about this subject to judge the plausibility of the claim but "graphene" and "limitless power" in the same headline does trigger a few red flags.
  - IgorPartola 6y ago
    You’ll still need a source of heat. This is a power converter not a source of free energy.
    - motoboi 6y ago
      But that means the graphene sheet need to be hotter than the surroundings? Or is this just converting heat from the air and infrared radiation into electric energy?
    - jack_riminton 6y ago
      So essentially its converting energy from the sun, via latent heat in the atmosphere into energy Could also use geothermal heat I guess
  - yourapostasy 6y ago
    I can't find the actual electrical power generated by the prototype circuit in the press releases, but it sounds like in the mA power range? It is "limitless" as long as the graphene mechanically survives (wonder how long that buckling will take to compromise the graphene) and there is some kind of minimum temperature maintained for the given required amount of electrical power output desired. Definitely not "free energy", but always good to reach further down into the physical realm in Feynman's "Plenty of Room at the Bottom" sense. I'm rooting around for alternative sources of the paper without success, but for those who have read it, what kind of graphene did they use (monolayer, CVD, GO, rGO, etc.)? I suspect that will somewhat throttle the manufacturing supply chain. Batteries are the least interesting application to me. This brings "sensor dust" out of solid fantasy into the realm of possibility in the far future; at first it will be "sensor clods", but let it follow the same evolutionary Shockley-to-ARM development path, and let's see where it goes. Permanently implanted medical chips to measure the blood, nervous and other internal medicine metrics we want to get our hands on might be more miniaturized; need to figure out how to extract out the incredibly weak signal.
    - MauranKilom 6y ago
      https://arxiv.org/abs/2002.09947 https://arxiv.org/abs/2002.09947
cowpig 6y ago
If I'm understanding the article correctly, a very tiny piece of graphene can pick up a very tiny amount of energy from the random jiggles at the atomic scale. Presumably, those jiggles are always going to be there, unless somehow earth becomes a cold, dead place. So imagine the solar panel on your calculator didn't need light, just a temperature above absolute zero.
- deleted 6y ago
  [deleted]
- gus_massa 6y ago
  This is exactly what the press release say, but this is impossible due the the Second Law of Thermodynamics. So (select at least one) 1) The press release is wrong 2) The research article is wrong 3) The Second Law of thermodynamics is wrong. [As a fast explanation, if the grapheme membrane and the lamp in the animation are at the same temperature, then the electrons in the lamp will get an equivalent amount of random jiggles and will counter the effect described in the article. (There may be also a similar problem with the diodes, capacitor, etc.)]

aduitsis 6y ago

Naive question, wouldn't this (converting Brownian motion into electricity) violate the 2nd law of thermodynamics? (edit, this is explicitly addressed further in the article: That's an important distinction, said Thibado, because a temperature difference between the graphene and circuit, in a circuit producing power, would contradict the second law of thermodynamics. "This means that the second law of thermodynamics is not violated, nor is there any need to argue that 'Maxwell's Demon' is separating hot and cold electrons," Thibado said.)

jl2718 6y ago
This sounds like a mangled explanation. It seems to me, somewhat naively, that the resonator must be held at a higher temperature than the rest of the circuit to produce work on the load.
- aduitsis 6y ago
  I think some minuscule amount of energy is taken from the thermal bath (the environment is considered a thermal bath - you can take heat from it and it's so big its temperature won't budge), converted into electricity and then back to heat in the load resistor. They all remain in the same temperature if I'm not gravely mistaken.
deleted 6y ago
[deleted]

xt00 6y ago

It’s more like “limitless power from heat transferred into graphene from an external power source”. So it’s a special type of a thermo electric generator basically.

ssivark 6y ago
Thank you; awful title.
ArtWomb 6y ago
Only in the load resistor. Electron flux in the graphene membrane appears to be solely due to geometry. This curvature does not necessarily need to be buckled via heat energy. It could be mechanical or electrical, if I understand things correctly... More detail in this video clip with UArk's Paul Thibado: https://www.youtube.com/watch?v=wrleMqm3HiU https://www.youtube.com/watch?v=wrleMqm3HiU I think what this research opens up is the possibility of "optimal" harvesting. There is some resonant frequency, some circuit configuration yet to be discovered that is perhaps self-sustaining. They've chosen "stochastic thermodynamical" circuits because its low hanging fruit. But it seems really exciting to me. Almost like a third class of energy production after solar and hydrogen (where 99% of research funds are allocated). Ocean wave energy harvesting perhaps? In any case, congrats to the researchers on their painstaking hard work ;) Fluctuation-induced current from freestanding graphene: toward nanoscale energy harvesting https://arxiv.org/abs/2002.09947 https://arxiv.org/abs/2002.09947
- IgorPartola 6y ago
  This does sound promising. Is it possible to run this process in reverse a la a heat pump to create an AC with no moving parts? Or is this purely a one way process?
  - arcticbull 6y ago
    Peltier coolers are probably in line with what you're suggesting, but they're not super efficient.

vitus 6y ago

> In the 1950s, physicist Léon Brillouin published a landmark paper refuting the idea that adding a single diode, a one-way electrical gate, to a circuit is the solution to harvesting energy from Brownian motion. Knowing this, Thibado’s group built their circuit with two diodes for converting AC into a direct current (DC). So, they built a full-wave rectifier (albeit with only 2 instead of, say, 4 diodes)? Pretty neat to see electrical engineering fundamentals at work. (also, for any who wanted specifics: article is at https://journals.aps.org/pre/abstract/10.1103/PhysRevE.102.042101 https://journals.aps.org/pre/abstract/10.1103/PhysRevE.102.0... ; abstract contains a couple of circuit diagrams) edit: updated link, thanks for pointing that out

yourapostasy 6y ago
Remove the semicolon at the end of the above link to get to the actual journal paper; paper is behind the APS paywall. Working link for the lazy: https://journals.aps.org/pre/abstract/10.1103/PhysRevE.102.042101 https://journals.aps.org/pre/abstract/10.1103/PhysRevE.102.0...

nayuki 6y ago

Is this based on the physics of the Seebeck effect to generate a voltage from a temperature difference? https://en.wikipedia.org/wiki/Thermoelectric_effect#Seebeck_effect https://en.wikipedia.org/wiki/Thermoelectric_effect#Seebeck_...

deleted 6y ago
[deleted]

kwhitefoot 6y ago

If this is representative of press releases from universities it's no wonder that people can't tell the difference between free energy scams and real physics. Sounds like nonsense to me but the article is so badly written that it's hard to tell. In fact it is hard to be sure whether they have actually created a prototype or merely simulated it.

tgsovlerkhgsel 6y ago
> If this is representative of press releases from universities If you want reporting that accurately represent science, in my experience, the university press releases are even worse than the worst mainstream shit-tier media.
- gspr 6y ago
  It's super sad. My boss was once at the center of one of these big press release splashes at the university I worked. She said it was almost more of a burden than a boon, because the attention it attracted was almost all of the wrong kind. And among the right kind of people, she had to spend time and effort excusing the embarassing and ridiculous press release. I wonder if universities understand that they're sometimes harming their own people with these things.
- barney54 6y ago
  The incentives for the PR team is to make news. They don’t have to spend a ton of time cleaning up the mess of misleading press releases.
  - gus_massa 6y ago
    At some point it tarnish the reputation of the university. If your university get famous for sending ridiculous press releases, I hope that eventually the journalist will notice and just forward them to The Onion.
    - raziel2701 6y ago

tsimionescu 6y ago

> The idea of harvesting energy from graphene is controversial because it refutes physicist Richard Feynman’s well-known assertion that the thermal motion of atoms, known as Brownian motion, cannot do work. Thibado’s team found that at room temperature the thermal motion of graphene does in fact induce an alternating current (AC) in a circuit, an achievement thought to be impossible. So it sounds like, if this really works, it may have some impact on our general understanding of thermodynamics or the properties of Brownian motion?

gus_massa 6y ago
If it works as described in the press release, this is a direct trip to Stockholm to pick the Nobel Prize. I can't read the research paper now. My guess is that there is a temperature difference between the grapheme and the resistor. In that case it's a normal experiment, perhaps with some tweak, but not a groundbreaking experiment. The power generated by the device is tiny (not "unlimited"), and there are a lot of similar devices. Sometimes the experiment is interesting in some niche (this experiment is related to tunnel microscopy) but this is totally overhyped.
- Animats 6y ago
  If it works as described in the press release, this is a direct trip to Stockholm to pick the Nobel Prize. There are too many PR announcements like that in the nanotechnology and battery areas. It's either Nobel Prize material or nothing, and you can't tell from the article. No power numbers. Are they talking about generating a picowatt or something like that? Somebody like EVworld should publish "1, 5 and 10 years ago today in energy announcements".
  - gus_massa 6y ago
    Most press release about batteries claim a x2 improvement in 5 years or something like that. If they were true perhaps you can get a Nobel, but you must wait in the queue for a few years. If you break the Second Law you can skip the queue and even the voting. > No power numbers. Are they talking about generating a picowatt or something like that? The figures in the research article claims ~1pW. I still can't get the research paper, but reading the information that is available, and some enlightening discussions in HN I guess they measured a ~1pW exchange of heat in the other side of the device (the "lamp" in the animation). But it is ~1pW in one direction and exactly the same amount in the other direction. There is no net energy flux or "useful" energy. This may be an useful experimental result in the research branch they are working, but not "Limitless Power".

zaroth 6y ago

So apparently this is the “small device eliminates need for AC” that I see advertised everywhere! </s> But in all seriousness, it seems this converts ambient heat (not a heat differential) directly into electricity. Therefore it must necessarily cool its surroundings by the equivalent energy extracted? So it’s a kind of air conditioner which doesn’t use electricity to move heat but rather converts heat directly to electricity? I thought we “knew” this was impossible...

philplckthun 6y ago
> “People may think that current flowing in a resistor causes it to heat up, but the Brownian current does not. In fact, if no current was flowing, the resistor would cool down,” Thibado explained. “What we did was reroute the current in the circuit and transform it into something useful.” Based on this I understood that it'd indeed cool down and create a heat gradient if it wasn't doing any work, but the difference it'd create is instead used to induce a current, which means it probably wouldn't cool down as long as that potential is used in this way instead (?)
Mountain_Skies 6y ago
If it works, it'd be a great cooler for electronics that could put back into the circuit some of the electricity that had been turned into heat. CPU and GPU coolers could become built into the structure of the ICs themselves.

bencollier49 6y ago

So how much energy would you harvest by using these en masse to reduce the temperature of the earth by around 2.5 degrees centigrade? (I appreciate this is highly unlikely to be possible).

kossTKR 6y ago

Can this be scaled up to provide power that isn't just a gimmick in the grand scheme of things?

r-bryan 6y ago

Without getting all quantum about it, it seems to work by configuring the graphene as one electrode (or both) of a capacitor. As the graphene flaps in the breeze (actually Brownian motion, I assume), the changing geometry will change the capacitance. If there is a charge on the cap, then the voltage would flap too, inversely (Q = CV). A changing voltage would tend to push about a current (i.e. charge motion). If their diodes somehow have a negligible forward voltage drop, then brief moments of higher voltage on the flappy cap would push increments of charge onto the storage cap (the one to the right of the diodes) until the storage cap voltage rose to equal the peak flappy voltage (minus the diode voltage drop). When the storage capacitance is greater than the flappy graphene capacitance, the stored energy will be greater than the tiny increments (energy = 1/2 CV^2). Then every so often the storage cap could be switched to drive some load. So why would there be a charge in the flappy capacitor? Well, a bias voltage is applied by this battery in the circuit. Ahem, before invoking any principles of thermodynamics, I'd like to see some detailed measurements, or even careful theory, of the current out of the battery and back into the battery, particularly w.r.t. the instantaneous voltages (P = VI), to prove that the time-average power delivered by the battery is precisely zero, or at least far lower than that putatively transferred to the load (light bulb in the animation). Otherwise it's behold, we found a high-resistance path for our battery to run a light bulb. There is some precedent for semiconductor thermal magic in the Peltier junction. It makes one end colder and the other end hotter by applying electric watts to it, with no moving parts aside from the electrons and holes recombining, or something. But nobody sees thermodynamics being violated or extended there. But here the magic is to take away thermal energy from one place, the flappy graphene (thereby cooling it) and moving the energy to the light bulb (thereby heating it). It seems you could then use any old heat engine to extract work by letting the heat flow from the resulting hotter place back to the colder place, getting "limitless power" for free from your perpetual motion machine. Conceivably it's a sort of heat pump that gets some multiplier above the battery power. But I think the burden of proof is on the Arkansas folks to explain how this can be. If I had more energy (no pun intended, really) right now I'd try to find the paper that the press release is based on, to see if there's a little more truth there. Meanwhile, I doubt it.

MauranKilom 6y ago
> Otherwise it's behold, we found a high-resistance path for our battery to run a light bulb. It's like a nano Rube Goldberg! Paper is here btw: https://arxiv.org/abs/2002.09947 https://arxiv.org/abs/2002.09947

sradman 6y ago

The abstract of the paper Fluctuation-induced current from freestanding graphene [1]: > At room temperature, micron-sized sheets of freestanding graphene are in constant motion, even in the presence of an applied bias voltage. We quantify the out-of-plane movement by collecting the displacement current using a nearby small-area metal electrode and present an Ito-Langevin model for the motion coupled to a circuit containing diodes. Numerical simulations show that the system reaches thermal equilibrium and the average rates of heat and work provided by stochastic thermodynamics tend quickly to zero. However, there is power dissipated by the load resistor, and its time average is exactly equal to the power supplied by the thermal bath. The exact power formula is similar to Nyquist's noise power formula, except that the rate of change of diode resistance significantly boosts the output power, and the movement of the graphene shifts the power spectrum to lower frequencies. We have calculated the equilibrium average of the power by asymptotic and numerical methods. Excellent agreement is found between experiment and theory. [1] https://journals.aps.org/pre/abstract/10.1103/PhysRevE.102.042101 https://journals.aps.org/pre/abstract/10.1103/PhysRevE.102.0...

mannykannot 6y ago
"However, there is power dissipated by the load resistor, and its time average is exactly equal to the power supplied by the thermal bath." As the "thermal bath" is supplying power, this seems consistent with it being a Carnot-equivalent heat engine. There is certainly nothing in physics that prevents the extraction of energy from an environment in which the temperature fluctuates - devices that do so to keep mechanical clocks running indefinitely have been around for some time. http://atmosadam.com/howitworks.html http://atmosadam.com/howitworks.html
- gus_massa 6y ago
  The clock in your link uses the temperature fluctuations, for example if it hot during the day and cool during the night. So you can have a flux of heat from the hot part to the cold part, and extract a small part as useful energy. If we take the press release at face value, in this device there is no difference of temperature. So if the Second Law of Thermodynamics is correct it is not possible to extract some useful energy to do something interesting, like turning on the lamp in the animation.

gus_massa 6y ago

Ignoring the horrible horrible horrible title ... This can only work if there is a temperature difference between the grapheme membrane and the load resistor (the lamp in the animations). Other wise, it breaks the Second Law of Thermodynamics. The problem is not that it breaks some remark from Feynman, the problem is that if there is no temperature difference, it breaks the Second Law of Thermodynamics and in particular an example in an explanation of Feynman.

ag56 6y ago
Doesn’t the article explicitly say that is not the case? > Though the thermal environment is performing work on the load resistor, the graphene and circuit are at the same temperature and heat does not flow between the two. I’m not a physicist or even an educated layman, can you explain your comment more?
- gus_massa 6y ago
  I read that part a few times, but it makes no sence. I prefer another quote > What we did was reroute the current in the circuit and transform it into something useful. Let's suppose that they get some "useful" energy to turn on the lamp like in the animation or power a small device. Let's suppose that you use it to power a laser and send a beam that heat some object far away. As a side effect, you are extracting energy from the device with the graphene in the lab so it will get cooler. So the net effect is that the device in the lab gets cooler and the object far away get hotter. So you have a flux of heat. But if the other object is hotter, you have a lux of heat from in the wrong direction, that is impossible according to the Second Law. There are a million ways to rewrite this https://en.wikipedia.org/wiki/Second_law_of_thermodynamics https://en.wikipedia.org/wiki/Second_law_of_thermodynamics in more abstract or more concrete ways. With some oversimplifications, another is that you need at least two heat baths and the efficiency of the device to transform heat from the "hot" bath to of "useful" energy can be calculate using the temperatures of the baths. When the difference of temperature is zero, the efficiency is zero and the device can produce no "useful" energy. Or in other words, with only one heath bath, you can produce no "useful" energy.

sandworm101 6y ago

So it converts heat into work without a temperature gradient? That is the real revolution. I wonder if this could scale into a cooling solution for chips.

itsshreyarora 6y ago

I read the words "limitless power" and assumed it is crap. In case it it not, please reply to this comment, and I will give the article a read. There is no reason for you to do this, but thanks in advance, kind strangers.

wtracy 6y ago
The article is indeed garbage. It smells like there's actually some interesting research being done here using graphene to extract energy from the ambient environment (possibly harvesting the work done as the graphene expands during hearing?) but the press release was written by someone who does not understand the subject at all.

wolfi1 6y ago

this is the doi of the paper: https://doi.org/10.1103/PhysRevE.102.042101 https://doi.org/10.1103/PhysRevE.102.042101

andi999 6y ago

If the title of this post were true, the paper would have been published in nature instead.

jostmey 6y ago
While I share your disappointment in the quality of the press release, Nature is by no means the bar for measuring significance. I've been both accepted and rejected by Nature, I've seen colleagues accepted and rejected by Nature, and I've found results published outside of Nature, Cell, Science more reproducible!
- andi999 6y ago
  I fully agree. But I still think if you could show violation of 2nd maw of thermodynamics and potentially solving all of human energy needs, I believe you would submit it to nature (or science). At least as signaling for getting funding for your trillion dollar startup commercializing the result.

stephc_int13 6y ago

Isn't it some kind of antenna? I might be completely wrong here, but I don't see that much of a difference, antennas are also "harvesting" power in some ways.