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Physicists Build Circuit That Generates Clean, Limitless Power from Graphene

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

#81

Post by Rury »

gus_massa wrote: post #55
ag56 wrote: post #42

Earlier quoted context omitted.

Doesn’t the article explicitly say that is not the case? > 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. I’m not a physicist or even an educated layman, can you explain your comment more?

I read that part a few times, but it makes no sence. I prefer another quote > What we did was reroute the current in the circuit and transform it into something useful. Let's suppose that they get some "useful" energy to turn on the lamp like in the animation or power a small device. Let's suppose that you use it to power a laser and send a beam that heat some object far away. As a side effect, you are extracting ene…

>So the net effect is that the device in the lab gets cooler and the object far away get hotter. So you have a flux of heat. But if the other object is hotter, you have a lux of heat from in the wrong direction, that is impossible according to the Second Law

I don't think your hypothesis would necessarily break the Second Law. Wouldn't the hotter distant object result in making Brownian motion around it? The same Brownian motion which would eventually end up as energy input at the graphene membrane - provided a thermodynamically closed system?

As so I'm not convinced this study breaks the Second Law, nor do I see how it produces useful work. To me it only seems so, because the system isn't being modeled as a closed system...

EDIT: Actually, I'm pretty sure the following statement is completely false:

>the graphene and circuit are at the same temperature and heat does not flow between the two.

I'd suspect heat does flow between the two, it's just outside their modeling of the system.

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

#82

Post by PicassoCTs »

vsskanth wrote: post #28
kwhitefoot wrote: post #15

If this is representative of press releases from universities it's no wonder that people can't tell the difference between free energy scams and real physics. Sounds like nonsense to me but the article is so badly written that it's hard to tell. In fact it is hard to be sure whether they have actually created a prototype or merely simulated it.

I am guessing the clickbait title is to make the article widely shared and attract funding. Probably have to read the journal paper to get accurate details.

In all honesty funding is given by institutions and people who evaluate the goal they spend there money on. So this sort of attention gathering, should be pre-filtered out by all serious sources of funding.

So what remains is a prestige, attention metric of the university.

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

#83

Post by MattGaiser »

PicassoCTs wrote: post #82
vsskanth wrote: post #28

Earlier quoted context omitted.

I am guessing the clickbait title is to make the article widely shared and attract funding. Probably have to read the journal paper to get accurate details.

In all honesty funding is given by institutions and people who evaluate the goal they spend there money on. So this sort of attention gathering, should be pre-filtered out by all serious sources of funding. So what remains is a prestige, attention metric of the university.

Money is money, whether it comes from a prestigious science institute or an old guy who inherited it and wants it spent on cool stuff.

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

#84

Post by gus_massa »

garmaine wrote: post #77
gus_massa wrote: post #75

Earlier quoted context omitted.

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.

I'm not sure was is your point. I'll try with another answer.

I don't remember something like the clock at the molecular level, but I think it is "theoretically possible" (or to be more accurate, "not theoretically impossible").

[Weird example warning]

In the mitochondria the ATP synthase https://en.wikipedia.org/wiki/ATP_synthase use the H+ difference of the inner and outer part to produce ATP. The main problem is how to create this difference without sugar or pyruvate, using only a change of temperature.

Perhaps it is possible to put a weak acid outside of a mitochondria, and select the weak acid that changes the dissociation constant a lot with the temperature.

So when temperature is high it is mostly dissociated and the acidity is high and the mitochondria produces ATP. But after some time there is no difference in the concentration of H+ inside and outside of the mitochondria and the process stop.

Then reduce the temperature so the acidity outside is low, and the H+ inside the mitochondria can escape by other pores. (Perhaps we need to make some additional pores for this? The pores must be small and not very polar.) After some time, the concentration of H+ inside the mitochondria is low again. And we can repeat the cycle.

[/Weird example warning]

This will be painfully slow and painfully inefficient. My biochemistry level is too low to be sure this is possible, but at lest I think it is not theoretically impossible.

It is a small system, so I think it is a relevant comparison in spite it is very different of a graphene membrane in a vacuum chamber.

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

#85

Post by IgorPartola »

arcticbull wrote: post #35
IgorPartola wrote: post #19

Earlier quoted context omitted.

This does sound promising. Is it possible to run this process in reverse a la a heat pump to create an AC with no moving parts? Or is this purely a one way process?

Peltier coolers are probably in line with what you're suggesting, but they're not super efficient.

I was hoping for an alternative to those. They are neat but with such low efficiency they aren’t super useful.

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

#86

Post by mannykannot »

gus_massa wrote: post #68
mannykannot wrote: post #61

Earlier quoted context omitted.

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…

> ...the problem is more subtle.

What is 'the problem' that you are apparently trying to address here? Everyone in the discussion is well aware that the 2nd. law of thermodynamics prevents the continuous extraction of work from ambient heat without there being a temperature difference. Are you saying that the paper is claiming that this has been done? If not that, are you claiming that the device, as described in the paper, is incapable of generating power from fluctuations in the ambient temperature? Have you identified some other problem in the paper? Alternatively - I don't think you are saying this, but I will put it in for completeness - could it be that you are saying that the paper shows that this team really has invented a Maxwell's diode, capable of continuously extracting work from the ambient heat of a closed system in thermal equilibrium?

If you are still only taking issue with the press release, you are just nerdsplaining to a bunch of people who already get it, thank you very much.

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

#87

Post by gus_massa »

mannykannot wrote: post #86
gus_massa wrote: post #68

Earlier quoted context omitted.

>> 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…

> ...the problem is more subtle. What is 'the problem' that you are apparently trying to address here? Everyone in the discussion is well aware that the 2nd. law of thermodynamics prevents the continuous extraction of work from ambient heat without there being a temperature difference. Are you saying that the paper is claiming that this has been done? If not that, are you claiming that the device, as described in the…

> Everyone in the discussion is well aware that the 2nd. law

Probably not, but it is good to know that you are.

The paper is not about a device that harvest energy from the thermal variations of the environment. There is no mention of macroscopic thermal variations in the press release or in the abstract of the paper. Also, the graphene is inside a ultra high vacuum chamber, that is a weird place to put a device that that depends on the macroscopic thermal variations of the environment.

From 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.

My interpretation is that the resistor is dissipating some power (from the graphics ~1pW), but it is also absorbing the same amount of power due to the 2nd law. It is not a Carnot engine that produces work from heat.

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

#88

Post by mannykannot »

gus_massa wrote: post #87
mannykannot wrote: post #86

Earlier quoted context omitted.

> ...the problem is more subtle. What is 'the problem' that you are apparently trying to address here? Everyone in the discussion is well aware that the 2nd. law of thermodynamics prevents the continuous extraction of work from ambient heat without there being a temperature difference. Are you saying that the paper is claiming that this has been done? If not that, are you claiming that the device, as described in the…

> Everyone in the discussion is well aware that the 2nd. law Probably not, but it is good to know that you are. The paper is not about a device that harvest energy from the thermal variations of the environment. There is no mention of macroscopic thermal variations in the press release or in the abstract of the paper. Also, the graphene is inside a ultra high vacuum chamber, that is a weird place to put a device that…

I am not sure what your claim is in that last paragraph. If it takes heat energy from the thermal bath and produces electrical energy (which is then dissipated in a load resistor), in what way is it not a Carnot engine?

Are you taking the quoted passage as implying it is performing 100% conversion? This would indeed be a problem, as there is no heat sink at 0K here. That quote, however, is ambiguous, as it says power supplied by the heat bath and not lost from it, and may merely be a statement that it obeys the conservation of energy (i.e. the point being made here may be that the power being supplied to the load comes from the heat bath, as opposed to coming from another possible source, such as the bias voltage supply.)

I really should buy and read the paper, but I am not that motivated yet.

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

#89

Post by gus_massa »

mannykannot wrote: post #88
gus_massa wrote: post #87

Earlier quoted context omitted.

> Everyone in the discussion is well aware that the 2nd. law Probably not, but it is good to know that you are. The paper is not about a device that harvest energy from the thermal variations of the environment. There is no mention of macroscopic thermal variations in the press release or in the abstract of the paper. Also, the graphene is inside a ultra high vacuum chamber, that is a weird place to put a device that…

I am not sure what your claim is in that last paragraph. If it takes heat energy from the thermal bath and produces electrical energy (which is then dissipated in a load resistor), in what way is it not a Carnot engine? Are you taking the quoted passage as implying it is performing 100% conversion? This would indeed be a problem, as there is no heat sink at 0K here. That quote, however, is ambiguous, as it says power…

It is not producing a macroscopic current, it is producing something like Johnson noise https://en.wikipedia.org/wiki/Johnson%E2%80%93Nyquist_noise (The interesting part seams to be that it has another frequency distribution, but I don't understand the details.)

A real engine transform heat into electric energy that can be used to dissipate heat inside a container at any temperature. In particular at a higher temperature that the graphene and the support and the circuit. In the PR they claim that it produce "something useful" that I interpret as "work" or "electrical energy", but in that case it breaks the Second Law even if in their setup the resistor is at the same temperature.

After reading the paragraph again, I'm not sure if your interpretation is right and they are claiming that the device is transferring energy from the graphene to the resistor, but that breaks the second law, in spite in the PR they claim it doesn't.

I think they never claim a 100% conversion anyway. They just don't have a temperature difference to operate the engine.

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

#90

Post by mannykannot »

gus_massa wrote: post #89
mannykannot wrote: post #88

Earlier quoted context omitted.

I am not sure what your claim is in that last paragraph. If it takes heat energy from the thermal bath and produces electrical energy (which is then dissipated in a load resistor), in what way is it not a Carnot engine? Are you taking the quoted passage as implying it is performing 100% conversion? This would indeed be a problem, as there is no heat sink at 0K here. That quote, however, is ambiguous, as it says power…

It is not producing a macroscopic current, it is producing something like Johnson noise https://en.wikipedia.org/wiki/Johnson%E2%80%93Nyquist_noise (The interesting part seams to be that it has another frequency distribution, but I don't understand the details.) A real engine transform heat into electric energy that can be used to dissipate heat inside a container at any temperature. In particular at a higher tempera…

Have you actually read the paper? So far, you have only supported your claims with references to the press release and the abstract. As it stands, you are alleging they have made a pretty serious blunder, which should not be made without reference to the paper itself.
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