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.
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.
I wonder if universities understand that they're sometimes harming their own people with these things.
Probably have to read the journal paper to get accurate details.
So what remains is a prestige, attention metric of the university.
More detail in this video clip with UArk's Paul Thibado:
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
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.
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.)]
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.
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.
Turning heat into usable energy without temperature differential is still an extraordinary claim that demands extraordinary evidence, but I wouldn't dismiss it out of hand
> 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?
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 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.
> 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.102.0...
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.
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.
(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.)
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?
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.
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".
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...
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 (?)
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.
It's like a nano Rube Goldberg!
Paper is here btw: https://arxiv.org/abs/2002.09947
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.102.0... ; abstract contains a couple of circuit diagrams)
edit: updated link, thanks for pointing that out
Working link for the lazy:
https://journals.aps.org/pre/abstract/10.1103/PhysRevE.102.0...
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.
I might be completely wrong here, but I don't see that much of a difference, antennas are also "harvesting" power in some ways.
