Physicists Build Circuit That Generates Clean, Limitless Power from Graphene • Hacker News Board

Re: Physicists Build Circuit That Generates Clean, Limitless Power from Graphene

#61

Post by mannykannot » Sat, Oct 03, 2020, 5:46 PM UTC

gus_massa wrote: post #49

mannykannot wrote: post #45

Earlier quoted context omitted.

"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 mechani…

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 usefu…

I am not inclined to take the press release at face value, as its author is apparently unaware of just how radical its claims are, if taken at face value, which in turn suggests that the author is out of his depth.

The above quote is from the abstract, and just before it, we see the much more reasonable "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."

Re: Physicists Build Circuit That Generates Clean, Limitless Power from Graphene

#62

Post by Animats » Sat, Oct 03, 2020, 5:50 PM UTC

gus_massa wrote: post #39

tsimionescu wrote: post #20

> 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…

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 s…

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".

Re: Physicists Build Circuit That Generates Clean, Limitless Power from Graphene

#63

Post by gumby » Sat, Oct 03, 2020, 6:13 PM UTC

vikramkr wrote: post #57

gus_massa wrote: post #51

Earlier quoted context omitted.

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.

MIT has a reputation for super sketchy press releases, but their research reputation is fine still. Even with the whole epstein scandal. I wonder how much it takes to actually tarnish their reputation.

There's no shortage of reasons to criticize at MIT but I'm not sure Epstein is one of them.

AFAICT the administration did not turn a blind eye to Epstein, and in fact barred him. And the scandal is that Joi knew that he was persona non grata and therefore took steps to hide Epstein's funding. That is unquestionably terrible but in my mind doesn't tar the Institute.

I'm certainly not defending (or criticizing) MIT as an institute (there are bigger problems than the dreadful press releases from the publicity office). But if my understanding is correct, Epstein, while lurid, might not be a useful line of attack.

Re: Physicists Build Circuit That Generates Clean, Limitless Power from Graphene

#64

Post by wtracy » Sat, Oct 03, 2020, 6:28 PM UTC

itsshreyarora wrote: post #41

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.

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.

Re: Physicists Build Circuit That Generates Clean, Limitless Power from Graphene

#65

Post by blablabla123 » Sat, Oct 03, 2020, 6:32 PM UTC

wongarsu wrote: post #56

gus_massa wrote: post #37

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 particu…

At least it doesn't break conservation of energy. The second law of thermodynamics is already kind of suspect in that random fluctuations break it all the time on a microscopic level. It's closer to a statistical observation. 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

The second law requires to take the average over a sufficiently long amount of time though.

Re: Physicists Build Circuit That Generates Clean, Limitless Power from Graphene

#66

Post by trhway » Sat, Oct 03, 2020, 6:57 PM UTC

digikata wrote: post #59

gus_massa wrote: post #49

Earlier quoted context omitted.

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 usefu…

It is difficult to tell at this level if they're claiming to have built Maxwell's Daemon out of graphene - or at least an approximation thereof.

imagine a very thin and very short wire - just for one electron to move a bit left and a bit right. The surrounding environment - in particular Brownian motion molecules, especially the ones with large dipole moment, and the background EM radiation - will cause the electron to move left-right. Thus we have electric current generation. Now diode-terminate the wire to allow aggregating of many of such wires without mutual cancellation of the current generated by those wires. Well, meet the Maxwell's Daemon remote cousin - Maxwell's Diode.

Basically, there are always local micro gradients even though the macro integration of those gradients gives 0. It may as well happen that graphene being few atoms thick and thus dipping into the local scale properties may bridge and aggregate without [total] mutual cancellation those properties into the macro scale (graphehe sheet vibrations may happen be [one of] such a filter, kind of piezoelectric effect). There is no violation of the 2nd law as extracted work/energy wouldn't be larger than the entropy increase resulting from the smoothing of the micro gradients (bringing the Universe's heat death closer).

Or even imagine a pond with no visible movement of water and place over it a myriad of very very small water mill wheels - they will be rotating chaotically back and forward due to small perturbances in the water (and the smaller a giving wheel the larger share of local gradient it will be extracting as the smaller share of it will be mutually cancelling with the neighboring gradients under the wheel). That chaotic rotation of that myriad of wheels can be aggregated into usable work/energy.

Re: Physicists Build Circuit That Generates Clean, Limitless Power from Graphene

#67

Post by andi999 » Sat, Oct 03, 2020, 7:13 PM UTC

jostmey wrote: post #58

andi999 wrote: post #46

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

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!

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.

Re: Physicists Build Circuit That Generates Clean, Limitless Power from Graphene

#68

Post by gus_massa » Sat, Oct 03, 2020, 8:18 PM UTC

mannykannot wrote: post #61

gus_massa wrote: post #49

Earlier quoted context omitted.

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 usefu…

I am not inclined to take the press release at face value, as its author is apparently unaware of just how radical its claims are, if taken at face value, which in turn suggests that the author is out of his depth. The above quote is from the abstract, and just before it, we see the much more reasonable "numerical simulations show that the system reaches thermal equilibrium and the average rates of heat and work prov…

>> 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.

It make sense, but the problem is more subtle. It's better compare the clock with a brick.

In the example of the clock there is a temperature difference that can be used to extract "useful" energy. You can use it to move the clock, or make a sound or light or something.

(I'm saying "useful" as in the a quote of the main author of the paper "What we did was reroute the current in the circuit and transform it into something useful.” .)

If you put a brick in a oven and keep it at the same temperature for some time, until the temperature, humidity and other properties have stabilized, you reach thermal equilibrium. It doesn't mean that the heat energy in the brick is perfectly constant, it exchanges heat with the oven. The heat energy has small random variations.

But unlike in the clock scenario, you can't use this additional accumulated energy for something "useful". To check if it is in a high or a low, you need a variant od the Maxwell's Demon. You can measure the energy exchange and analyze the theoretical and experimental properties anyway.

(Also, if you put the clock in the oven at a constant temperature for a long enough time, it will stop working.)

Stealing the name from a sibling thread, to make the grapheme device produce "useful" energy, you probably need a Maxwell's Diode.

Re: Physicists Build Circuit That Generates Clean, Limitless Power from Graphene

#69

Post by garmaine » Sat, Oct 03, 2020, 8:27 PM UTC

gumby wrote: post #63

vikramkr wrote: post #57

Earlier quoted context omitted.

MIT has a reputation for super sketchy press releases, but their research reputation is fine still. Even with the whole epstein scandal. I wonder how much it takes to actually tarnish their reputation.

There's no shortage of reasons to criticize at MIT but I'm not sure Epstein is one of them. AFAICT the administration did not turn a blind eye to Epstein, and in fact barred him. And the scandal is that Joi knew that he was persona non grata and therefore took steps to hide Epstein's funding. That is unquestionably terrible but in my mind doesn't tar the Institute. I'm certainly not defending (or criticizing) MIT as…

Also MIT != MIT Media Lab. (Although in terms of reputation the two are usually conflated.)

Re: Physicists Build Circuit That Generates Clean, Limitless Power from Graphene

#70

Post by MauranKilom » Sat, Oct 03, 2020, 8:27 PM UTC

r-bryan wrote: post #32

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 thei…

> 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