Physicists build circuit that generates clean limitless power from graphene
thebrighterside.news
thebrighterside.news
Even more, the result is essentially claiming to violate the Second Law Of Thermodynamics. HN should be flagging this sort of crank claim.
“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. “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.”
Anyway, if you see the animation in the video, they are trying to makes a device that use this effect to collect the charge in a capacitor and then release the energy in a resistor, and that proposed device breaks the second law, in particular is more clear with this version https://en.wikipedia.org/wiki/Second_law_of_thermodynamics#P...
turns out I just got in a little too soon.. ugh
Our model provides a rigorous demonstration that continuous thermal power can be supplied by a Brownian particle at a single temperature while in thermodynamic equilibrium, provided the same amount of power is continuously dissipated in a resistor. Here coupling to the circuit allows electrical work to be carried out on the load resistor without violating the second law of thermodynamics.
I don't find this very clear at all, but it appears to contradict the claim that the setup could be used for energy harvesting.
The idea is that at room temperature, the Brownian motion moves the graphene, and that generates a small current in the circuit, so the circuits absorbs some energy from the environment. But there is electric noise in the circuit, and that noise makes the graphene move as a motor and release some energy to the environment. One of the consequence of the second law is that if all the circuit and environment are at the same temperature, the energy absorbed an the energy released are equal, so the net effect is zero.
Now if you look at the resistance, the noise in the circuit makes it release some energy as heat, but the Brownian motion of makes it generate some noise. Again, one of the consequence of the second law is that if all the circuit and environment are at the same temperature, the energy absorbed an the energy released are equal, so the net effect is zero.
And now, considering the diodes, ..., the second law ..., so the net effect is zero.
And now, considering the wires (wires are small resistances), ..., the second law ..., so the net effect is zero.
And now, considering the mechanical support of the circuit (small devices are weird), ..., the second law ..., so the net effect is zero.
The problem is that in spite what the article says, a consequence of the Second Law of Thermodynamics is that if all the device is at the same temperature it's not possible to "generates clean limitless power".
> At room temperature, micron-sized sheets of freestanding graphene are in constant motion
[1] https://journals.aps.org/pre/abstract/10.1103/PhysRevE.102.0...
Imagine air molecules colliding with the sheet causing buckles to form, invert, or flatten out, with the deformation popping up nearby.
Each time it buckles, a tiny current is generated. If it buckles in one direction, current goes one way, if it buckles in the other direction, current goes the other way.
Because of quantum effects - brownian motion - no collisions have to occur, the heat going into the graphene sheet itself is enough to chaotically produce buckling, with a direct transformation of mechanical energy deformation to electricity.
Heat storage is really easy. It'll be interesting to see how efficiency scales, in practice. If it exceeds modern thermoelectric performance, it's got a future, but this might get really high efficiency. The limit is the effective surface area of the graphene.
Because it's solid state, it makes low temperature / shallow geothermal much more feasible.
No gradient needed is the revolutionary phenomena here. It's a solid state quantum motion based electricity generator. The higher the temperature, the more rapid the brownian motion, the more power is produced.
What I don't understand is what would happen if you put a bunch of these inside a highly insulated really hot cavity. The paper suggests that it doesn't cool down while generating current, but that it cools while no current is being drawn. Is that just a "wtf, nature?!" thing or is something being missed?
I can't wait for this to be replicated.
Wouldn't the net current be zero with no gradient? We're not violating any laws of thermodynamics here.
The weird bit is the cooling while not passing current. Does the system as a whole have a tendency to cool, and why does removing energy as electricity not cool it down? Is the quantum buckling effectively separated from the heat of the system? Particles are weird.
The quantum mechanics effect of the membrane make are real and produce effect like the Zero-energy point https://en.wikipedia.org/wiki/Zero-point_energy
But the article is about noise caused by Brownian motion, that is a classic mechanics effect https://en.wikipedia.org/wiki/Brownian_motion
If that's the case, then by definition, as current is produced, energy is taken from the collisions mechanically, and temperature would decrease. Thibado says that when current is not flowing the resistor cools down, and implies that when current is flowing, it doesn't heat up.
>>“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.”
If current is produced and the system isn't extracting heat (cooling) then the energy has to come from somewhere, right? That's why I was assuming they were talking about the Brownian motion of the graphene itself. If it's just the graphene, the system would work in a vacuum. If it's air molecules then Thibado has to be wrong, or the quote was sloppy or out of context.
I'm gonna reread the paper, at least.
The idea is that the resistor acts as a small generator that produces a current that is electric notice. This transform some mechanical energy into electricity, and in a magical universe it would cool down the resistor.
The problem is that the rest of the circuit is also producing electric noise. So the small current of the noise of the rest of the circuit goes to the resistor and is dissipated as heat and warms the resistor.
If you live in a magical word, you can magically turn off the noise of the rest of the circuit, but in the real word that is impossible and both effect cancel and the resistor keeps it's temperature.
This is pretty standard theory, but perhaps it's not the best way to explain it.
My guess is that the important result of the research paper is that the spectrum of the noise of the part of the circuit with the graphene is different of the spectrum of the noise of the resistor. It's interesting, but it does not break the current laws of Physics.
>>> What we did was reroute the current in the circuit and transform it into something useful
That's a direct jump into the "totally wrong or Nobel price" category. That's a claim that breaks the Second Law, so they are totally wrong or they get a Nobel price, there is no middle ground. (Sometimes the Nobel committee takes a few year to assign the price, but a result like this would cause immediately a huge discussion in the Physic community, like the discovery of the Higgs boson or LIGO.)
That this is even thermodynamically possible is an exciting development, would be interesting to see if it's possible to scale up the results at all.
I am using Chrome v1024.999.99 (at least my user-agent says so) why it's not supported?
Devtools -> Disable Javascript, I can load the contents again!
back on topic: Which side of the lab door were on?
Hard to tell what shitty browser detection they use that doesn't turn the version number into a number before comparising the two, but this is why both Chrome and Firefox are hesitant about releasing version 100 of their browser.