Excerpts：
"A team of University of Arkansas physicists has successfully developed a circuit capable of capturing graphene's thermal motion and converting it into an electrical current."
"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."
first analysed in 1912 ... by Polish physicist Marian Smoluchowski. ... popularised by [Feynman] in a physics lecture at the California Institute of Technology on May 11, 1962,
When correctly shaped, graphene can harvest energy from motion, such as human body movements, and store it as electrical energy in micro-supercapacitors.
Clocks that wind themselves up from being jostled around are centuries old. But thermal energy is supposed to be maximally disordered and thus unable to be converted to a more ordered form like electricity.
I would read the article, it is easy to read and accessible.
Here's the meat though.
"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.
According to Kumar, the graphene and circuit share a symbiotic relationship. 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.
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."
A circuit producing power without a temperature difference contradicts the second law of thermodynamics, which is what Thibado is claiming to have done.
Hard to see how this works when Brownian ratchets don't.
Also: "Léon Brillouin in 1950 discussed an electrical circuit analogue that uses a rectifier (such as a diode) instead of a ratchet. The idea was the diode would rectify the Johnson noise thermal current fluctuations produced by the resistor, generating a direct current which could be used to perform work. In the detailed analysis it was shown that the thermal fluctuations within the diode generate an electromotive force that cancels the voltage from rectified current fluctuations. Therefore, just as with the ratchet, the circuit will produce no useful energy if all the components are at thermal equilibrium (at the same temperature); a DC current will be produced only when the diode is at a lower temperature than the resistor."
But if the diode at a lower temperature than the resistor can generate current, then the current should raise the temperature of the resistor, meaning that it will stay running.
That seems unlikely, as I understand thermodynamics. Can anyone explain?
This is pretty meaningless argument though. Ok, maybe it does not contradict the second law of thermodynamics. It still contradicts the conservation of energy though, and that's what matters!
(It also does not contradict law of conservation of momentum, Boltzmann law, and San Francisco parking rules. Who cares?)
The abstract doesn't appear to me to say anything about violating known physical law.
They are claiming it all works as theory predicts, I think.
What is missing for me is an explanation why this is in fact interesting to a layperson.
"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."
I guess it sounds like they are saying the graphene is all wibbly-wobbly at room temperature, and applying a kind of damping mechanism temporarily produces power. Very temporarily.
I'm not quite sure why this should or should not be possible. If they say it's initially not at equilibrium though, that means they aren't suggesting new physics, right?
It is nonsense. The claim is that a machine exists that violates the 2nd law of thermodynamics (definition of a perpetual motion machine, Maxwell's Demon). This is well trodded ground.
I didn't read the whole article, but from the schematics it looks like they are exploiting thermal electronic noise and applying a half-bridge rectifier to it so it produces very low voltage power.
On one hand, it's clearly bullshit due to the extravagant title claiming to violate the 2nd law of thermodynamics. On the other hand, if a system is sufficiently small than it can violate the 2nd law, locally. It seems the tour de force in this case is that the scale can be somewhat enlarged by the very low power of thermal electronic noise.
A previous time this came up, I had the impression that what it really does is extract energy from a temperature difference between the graphene and the load, which is in principle perfectly normal even is it's a new way to arrange the details.
Edit: missed the link to the abstract.
However, there is power dissipated by the load resistor, and its time average is exactly equal to the power supplied by the thermal bath.
So yeah, extracting power from a thermal bath sounds exactly like capturing energy as it flows down a temperature gradient.
Nope. Not reproduced since then. One of these classic "hey I've discovered an effect that is not properly isolated and contradicts brownian motion. Everything we know is probably wrong, let's publish about it rather than try to understand what we screwed up" moments.
Even in utopian depictions of the future energy tends not to be limitless. Extremely abundant maybe, but never limitless. It seems strange to even pursue it.
Excerpts： "A team of University of Arkansas physicists has successfully developed a circuit capable of capturing graphene's thermal motion and converting it into an electrical current."
"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."
Sounds like a piezo sensor
As a freshman EE I suggested this as a potential source of power. Got bad marks on the assignment.
There's nobody to give this research group bad marks.
The thermal motion of atoms in a coal fire can do work just fine. All you need is a steam engine and a cold reservoir.
It seems odd to mention Feynman here even if he did say it. Surely he wasn't the only or first person?
Surely he was joking.
What do you care?
I see what you did there
Maybe this is it?
https://en.wikipedia.org/wiki/Brownian_ratchet
It’s an allusion to the Brownian ratchet thought experiment. AFAIK he demonstrated why it does not work.
Producing electricity from Brownian motion ?!
It's been two years, what is their progress? It has probably failed to be exploitable then ?
Quick Google search finds the concept being used in medical sensors. https://www.sciencedaily.com/releases/2022/03/220301205420.h...
When correctly shaped, graphene can harvest energy from motion, such as human body movements, and store it as electrical energy in micro-supercapacitors.
Motion is one thing, thermal motion is another.
Clocks that wind themselves up from being jostled around are centuries old. But thermal energy is supposed to be maximally disordered and thus unable to be converted to a more ordered form like electricity.
ScholarlyArticles that cite "Fluctuation-induced current from freestanding graphene" (2020) https://scholar.google.com/scholar?cites=3748350803951231734...
Previous discussion 2020-10: https://news.ycombinator.com/item?id=24671279
Or less than 24h ago: https://news.ycombinator.com/item?id=30817793 (same article, different domain) With a link therein to another post less than a month ago.
Limitless energy? Doesn’t that violate the first law?
Is this clickbait? Or, is there actual basis to the claim?
Kindly, someone who knows about this space elaborate?
I would read the article, it is easy to read and accessible.
Here's the meat though.
"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.
According to Kumar, the graphene and circuit share a symbiotic relationship. 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.
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."
Thanks
A circuit producing power without a temperature difference contradicts the second law of thermodynamics, which is what Thibado is claiming to have done.
Hard to see how this works when Brownian ratchets don't.
Also: "Léon Brillouin in 1950 discussed an electrical circuit analogue that uses a rectifier (such as a diode) instead of a ratchet. The idea was the diode would rectify the Johnson noise thermal current fluctuations produced by the resistor, generating a direct current which could be used to perform work. In the detailed analysis it was shown that the thermal fluctuations within the diode generate an electromotive force that cancels the voltage from rectified current fluctuations. Therefore, just as with the ratchet, the circuit will produce no useful energy if all the components are at thermal equilibrium (at the same temperature); a DC current will be produced only when the diode is at a lower temperature than the resistor."
https://en.wikipedia.org/wiki/Brownian_ratchet
But if the diode at a lower temperature than the resistor can generate current, then the current should raise the temperature of the resistor, meaning that it will stay running.
That seems unlikely, as I understand thermodynamics. Can anyone explain?
Current in a resistor will raise the resistor's temperature.
Current in a diode also raises the diode's temperature.
It takes work to keep the diode at a lower temp.
The diode won't be at a lower temperature for very long.
This is pretty meaningless argument though. Ok, maybe it does not contradict the second law of thermodynamics. It still contradicts the conservation of energy though, and that's what matters!
(It also does not contradict law of conservation of momentum, Boltzmann law, and San Francisco parking rules. Who cares?)
The abstract doesn't appear to me to say anything about violating known physical law.
They are claiming it all works as theory predicts, I think.
What is missing for me is an explanation why this is in fact interesting to a layperson.
"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."
I guess it sounds like they are saying the graphene is all wibbly-wobbly at room temperature, and applying a kind of damping mechanism temporarily produces power. Very temporarily.
I'm not quite sure why this should or should not be possible. If they say it's initially not at equilibrium though, that means they aren't suggesting new physics, right?
AC, eh?
680kHz perhaps?
The first thing they should do it hook up this radio frequency “AC” to a speaker and see if it sounds like country music or traffic reports.
AC in a high impedance circuit is practically unavoidable, graphene or not.
It is nonsense. The claim is that a machine exists that violates the 2nd law of thermodynamics (definition of a perpetual motion machine, Maxwell's Demon). This is well trodded ground.
https://youtu.be/rckrnYw5sOA
Did this team discover Johnson noise?
TFW you see “Limitless” and “Power” in the same sentence.
I didn't read the whole article, but from the schematics it looks like they are exploiting thermal electronic noise and applying a half-bridge rectifier to it so it produces very low voltage power.
On one hand, it's clearly bullshit due to the extravagant title claiming to violate the 2nd law of thermodynamics. On the other hand, if a system is sufficiently small than it can violate the 2nd law, locally. It seems the tour de force in this case is that the scale can be somewhat enlarged by the very low power of thermal electronic noise.
“This means that the second law of thermodynamics is not violated, " -Paul Thibado, professor, physics.
Title is awful ofc but the actual scientist of course never claimed this.
That was easy.
This is from 2020.
Since the followup isn't "Arkansas Graphene Power 10GW plant comes online", it probably doesn't generate "clean, limitless power".
At least not cheaply. As far as I'm aware (may be wrong) we still are unable to build graphene at scale, let alone graphene circuits.
A previous time this came up, I had the impression that what it really does is extract energy from a temperature difference between the graphene and the load, which is in principle perfectly normal even is it's a new way to arrange the details.
Edit: missed the link to the abstract.
So yeah, extracting power from a thermal bath sounds exactly like capturing energy as it flows down a temperature gradient.
Is this meant to be an early April Fools joke?
Nope. Not reproduced since then. One of these classic "hey I've discovered an effect that is not properly isolated and contradicts brownian motion. Everything we know is probably wrong, let's publish about it rather than try to understand what we screwed up" moments.
Headline like these are automatically ignorable. Why is this even upvoted. "Limitless" power is just always false.
Even in utopian depictions of the future energy tends not to be limitless. Extremely abundant maybe, but never limitless. It seems strange to even pursue it.
In any possible Utopian future, our energy usage will expand to match our energy production. As more energy is produced, more uses is found to use it.