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

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

#71

Post by garmaine » Sat, Oct 03, 2020, 8:31 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…

There is no such thing as temperature at the scale they are taking about. There is only Brownian motion with a random distribution of impact speeds from surrounding molecules. At any given time the graphene might be experiencing more or less force over its area than the thermal average.

Another way of thinking about it is that random noise although uniform at large scale, is intrinsically noisy when you zoom in.

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

#72

Post by MauranKilom » Sat, Oct 03, 2020, 8:32 PM UTC

yourapostasy wrote: post #26

simias wrote: post #9

Earlier quoted context omitted.

That's how I understand it as well. It harvest the brownian motion of atoms in graphene. 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.

I can't find the actual electrical power generated by the prototype circuit in the press releases, but it sounds like in the mA power range? It is "limitless" as long as the graphene mechanically survives (wonder how long that buckling will take to compromise the graphene) and there is some kind of minimum temperature maintained for the given required amount of electrical power output desired. Definitely not "free en…

https://arxiv.org/abs/2002.09947

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

#73

Post by Mountain_Skies » Sat, Oct 03, 2020, 9:00 PM UTC

zaroth wrote: post #27

So apparently this is the “small device eliminates need for AC” that I see advertised everywhere! 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 electri…

If it works, it'd be a great cooler for electronics that could put back into the circuit some of the electricity that had been turned into heat. CPU and GPU coolers could become built into the structure of the ICs themselves.

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

#74

Post by stephc_int13 » Sat, Oct 03, 2020, 9:08 PM UTC

Isn't it some kind of antenna?

I might be completely wrong here, but I don't see that much of a difference, antennas are also "harvesting" power in some ways.

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

#75

Post by gus_massa » Sat, Oct 03, 2020, 10:08 PM UTC

garmaine wrote: post #71

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…

There is no such thing as temperature at the scale they are taking about. There is only Brownian motion with a random distribution of impact speeds from surrounding molecules. At any given time the graphene might be experiencing more or less force over its area than the thermal average. Another way of thinking about it is that random noise although uniform at large scale, is intrinsically noisy when you zoom in.

The temperature can be defined even for very small systems using Statistical Mechanics, and also the distribution of speeds and energy in the Brownian motion of the surrounding molecules and movement of the membrane (and phonons?) depend on the temperature.

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

#76

Post by gus_massa » Sat, Oct 03, 2020, 10:19 PM UTC

Animats wrote: post #62

gus_massa wrote: post #39

Earlier quoted context omitted.

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 a…

Most press release about batteries claim a x2 improvement in 5 years or something like that. If they were true perhaps you can get a Nobel, but you must wait in the queue for a few years. If you break the Second Law you can skip the queue and even the voting.

> No power numbers. Are they talking about generating a picowatt or something like that?

The figures in the research article claims ~1pW. I still can't get the research paper, but reading the information that is available, and some enlightening discussions in HN I guess they measured a ~1pW exchange of heat in the other side of the device (the "lamp" in the animation). But it is ~1pW in one direction and exactly the same amount in the other direction. There is no net energy flux or "useful" energy.

This may be an useful experimental result in the research branch they are working, but not "Limitless Power".

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

#77

Post by garmaine » Sat, Oct 03, 2020, 10:29 PM UTC

gus_massa wrote: post #75

garmaine wrote: post #71

Earlier quoted context omitted.

There is no such thing as temperature at the scale they are taking about. There is only Brownian motion with a random distribution of impact speeds from surrounding molecules. At any given time the graphene might be experiencing more or less force over its area than the thermal average. Another way of thinking about it is that random noise although uniform at large scale, is intrinsically noisy when you zoom in.

The temperature can be defined even for very small systems using Statistical Mechanics, and also the distribution of speeds and energy in the Brownian motion of the surrounding molecules and movement of the membrane (and phonons?) depend on the temperature.

This is true. It also has nothing to do with the point I was making.

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

#78

Post by WORLD_ENDS_SOON » Sat, Oct 03, 2020, 10:34 PM UTC

ArtWomb wrote: post #18

xt00 wrote: post #6

It’s more like “limitless power from heat transferred into graphene from an external power source”. So it’s a special type of a thermo electric generator basically.

Only in the load resistor. Electron flux in the graphene membrane appears to be solely due to geometry. This curvature does not necessarily need to be buckled via heat energy. It could be mechanical or electrical, if I understand things correctly... 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" h…

I'm completely out of my area of expertise here (I can mostly follow the press release but I can't understand that much of the actual paper outside of the introduction), but your comment about resonant frequencies reminded me of of some recent research on layering graphene at a "magic angle" to produce special fractal moire patterns that have special physical properties. I wonder if that work can be combined with the work here. To a non expert like myself, it seems like there is a lot of really exciting research in this area at the moment.

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

#79

Post by srtjstjsj » Sat, Oct 03, 2020, 10:55 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…

An institution is its people. If institutional policies aren't followed, the reputation suffers.

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

#80

Post by gumby » Sat, Oct 03, 2020, 11:25 PM UTC

srtjstjsj wrote: post #79

gumby wrote: post #63

Earlier quoted context omitted.

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 institution is its people. If institutional policies aren't followed, the reputation suffers.

Well sure, but the point is the institution put a stop mechanism in place, when it was found out that someone had worked around it then a group of them were canned too. The media lab is a tiny part of the smallest school in a very large institution and the sums were correspondingly trivial compared to the institute's annual budget. (even all of education is a small fraction of that budget).

It's as if Google's parking valets were found to be running a car theft ring (made up example): unless Google seemed to think it below their notice, I would have a hard time considering that should be grounds for condemning Google.

I'm not defending MIT (or conflating car theft with sexual abuse) I'm merely saying that if you want to attack MIT consider something more substantive like its slow progress in recruiting and retaining female scientists; it's intimate ties with the government and military (despite various fig leaves assembled over the decades), or its treatment of undergraduates which at best is neglect. Don't waste your efforts on a small, if noisy, lab that has produced negligible research of consequence.