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Physicists build circuit that generates clean limitless power from graphene

49 points by mardiyah 5y ago

bagels 5y ago
Where does the energy come from? The environment surrounding the chip?
est 5y ago
This websie says "Your browser is no longer supported" 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!
- NamTaf 5y ago
  Given that the latest version of Chrome is 98.0.4758, if yours is reporting a strange version number like that then it could well fall outside the bounds of whatever check they put in. https://en.wikipedia.org/wiki/Google_Chrome https://en.wikipedia.org/wiki/Google_Chrome
- tejtm 5y ago
  At least it did not send an alert that you were "offline" back on topic: Which side of the lab door were on?
- jeroenhd 5y ago
  In Javascript, "99" > "10000000" === true. Naive user agent parsing libraries will fall for this problem while they're trying to block out known bad browsers. 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.
dvt 5y ago
This is really interesting, but can anyone explain the mechanism behind why this happens[1]: > At room temperature, micron-sized sheets of freestanding graphene are in constant motion [1] https://journals.aps.org/pre/abstract/10.1103/PhysRevE.102.042101 https://journals.aps.org/pre/abstract/10.1103/PhysRevE.102.0...
- selimthegrim 5y ago
  Graphene buckles, that is in theory its lowest energy state is not flat as a sheet. This is part of the original thermodynamic arguments against graphene's existence that were disproved by finding it. I think the Mermin-Wagner theorem used to be invoked.
- robbedpeter 5y ago
  The graphene isn't pulled taut like a sheet pulled flat, but slightly loose, like a sheet slightly drooping, and the graphene naturally buckles and deforms. 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.
  - willis936 5y ago
    >No gradient needed Wouldn't the net current be zero with no gradient? We're not violating any laws of thermodynamics here.
    - tormeh 5y ago
lumost 5y ago
Very curious to learn more about the underlying research. My understanding is that this would be the first example device which can extract thermal energy from Brownian motion without a temperature gradient. 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.
nest0r 5y ago
etaioinshrdlu 5y ago
This seems highly unlikely. Does it just spontaneously become cold as power is generated?
joe_the_user 5y 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. Even more, the result is essentially claiming to violate the Second Law Of Thermodynamics. HN should be flagging this sort of crank claim.
- zdragnar 5y ago
  How so? Isn't it just converting the effect of thermal energy to electric energy? Presumably, there is no Brownian motion at absolute zero, and the actual output would drop well above that temperature.
  - fsh 5y ago
    A direct conversion of thermal energy into electric energy would cool down the entire system. Since electric energy carries no entropy, this would reduce the overall entropy of the system. This is forbidden by the second law of thermodynamics.
    - actually_a_dog 5y ago
      It's not a closed system.
      - gus_massa 5y ago
        The "system" is the circuit (including the graphene), a closed box around it and the gas that is inside the box.
      - Rury 5y ago
        If treated as a closed system, the claim would indeed be violating the second law of thermodynamics. If it's treated as an open system, then well yeah... the "limitless" energy is actually coming from outside the boundaries of the system, which they conveniently neglect to track. No magic to be had here, but a cool way to convert energy...
fsh 5y ago
I just skimmed the paper. Right in the end of the discussion, the authors write: 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.
- deleted 5y ago
  [deleted]
gus_massa 5y ago
If this work as described in the press article, it breaks the second law of thermodynamics, in spite they claim it doesn't. It's based in a research article published in 2020, so if they didn't win the Nobel price 2021, it's pretty clear that it does not "generates clean limitless power". 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".
rambojazz 5y ago
"limitless power"? The choice of words doesn't make it sound like something worth reading

49 points by mardiyah 5y ago

Where does the energy come from? The environment surrounding the chip?

est 5y ago

This websie says "Your browser is no longer supported" 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!

NamTaf 5y ago
Given that the latest version of Chrome is 98.0.4758, if yours is reporting a strange version number like that then it could well fall outside the bounds of whatever check they put in. https://en.wikipedia.org/wiki/Google_Chrome https://en.wikipedia.org/wiki/Google_Chrome
tejtm 5y ago
At least it did not send an alert that you were "offline" back on topic: Which side of the lab door were on?
jeroenhd 5y ago
In Javascript, "99" > "10000000" === true. Naive user agent parsing libraries will fall for this problem while they're trying to block out known bad browsers. 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.

dvt 5y ago

This is really interesting, but can anyone explain the mechanism behind why this happens[1]: > At room temperature, micron-sized sheets of freestanding graphene are in constant motion [1] https://journals.aps.org/pre/abstract/10.1103/PhysRevE.102.042101 https://journals.aps.org/pre/abstract/10.1103/PhysRevE.102.0...

selimthegrim 5y ago
Graphene buckles, that is in theory its lowest energy state is not flat as a sheet. This is part of the original thermodynamic arguments against graphene's existence that were disproved by finding it. I think the Mermin-Wagner theorem used to be invoked.
robbedpeter 5y ago
The graphene isn't pulled taut like a sheet pulled flat, but slightly loose, like a sheet slightly drooping, and the graphene naturally buckles and deforms. 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.
- willis936 5y ago
  >No gradient needed Wouldn't the net current be zero with no gradient? We're not violating any laws of thermodynamics here.
  - tormeh 5y ago

lumost 5y ago

Very curious to learn more about the underlying research. My understanding is that this would be the first example device which can extract thermal energy from Brownian motion without a temperature gradient. 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.

nest0r 5y ago

etaioinshrdlu 5y ago

This seems highly unlikely. Does it just spontaneously become cold as power is generated?

joe_the_user 5y 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. Even more, the result is essentially claiming to violate the Second Law Of Thermodynamics. HN should be flagging this sort of crank claim.

zdragnar 5y ago
How so? Isn't it just converting the effect of thermal energy to electric energy? Presumably, there is no Brownian motion at absolute zero, and the actual output would drop well above that temperature.
- fsh 5y ago
  A direct conversion of thermal energy into electric energy would cool down the entire system. Since electric energy carries no entropy, this would reduce the overall entropy of the system. This is forbidden by the second law of thermodynamics.
  - actually_a_dog 5y ago
    It's not a closed system.
    - gus_massa 5y ago
      The "system" is the circuit (including the graphene), a closed box around it and the gas that is inside the box.
    - Rury 5y ago
      If treated as a closed system, the claim would indeed be violating the second law of thermodynamics. If it's treated as an open system, then well yeah... the "limitless" energy is actually coming from outside the boundaries of the system, which they conveniently neglect to track. No magic to be had here, but a cool way to convert energy...

fsh 5y ago

I just skimmed the paper. Right in the end of the discussion, the authors write: 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.

deleted 5y ago
[deleted]

gus_massa 5y ago

If this work as described in the press article, it breaks the second law of thermodynamics, in spite they claim it doesn't. It's based in a research article published in 2020, so if they didn't win the Nobel price 2021, it's pretty clear that it does not "generates clean limitless power". 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".

rambojazz 5y ago

"limitless power"? The choice of words doesn't make it sound like something worth reading