Guest essay by Eric Worrall
A meme has started circulating on the internet about graphene batteries providing unlimited free energy, harvested from the random Brownian Motion of the graphene. But there is another possible explanation, which the researchers may have overlooked.
From 2020;
Physicists Just Showed That Graphene Circuits Can Produce Clean, Limitless Power
DAVID NIELD
6 OCTOBER 2020Scientists have been able to draw power from the thermal motion of graphene at room temperature, potentially giving us a clean future source of limitless energy for small devices.
The approach cleverly harnesses both the nanometre-sized rippling and the Brownian motion – random movement of particles – found in graphene, producing an electric current that could be put to a variety of uses.
“An energy-harvesting circuit based on graphene could be incorporated into a chip to provide clean, limitless, low-voltage power for small devices or sensors,” says physicist Paul Thibado, from the University of Arkansas.
The research draws on previous work from the same lab, in which freestanding graphene was shown to ripple and buckle in a way that could be harvested for energy.
“The origin of these nanometre-sized ripples is still an open question,” the team writes in their study, noting that the graphene ripple seems to stem from subatomic particle interactions in the material.
A crucial part of the development of their system was using two diodes in the circuit to convert the original alternating current (AC) into direct current (DC). This allowed the current to flow both ways through the circuit, along separate paths.
…
Read more: https://www.sciencealert.com/physicists-build-a-circuit-from-graphene-that-generates-clean-limitless-power
The abstract of the paper;
Fluctuation-induced current from freestanding graphene
P. M. Thibado, P. Kumar, Surendra Singh, M. Ruiz-Garcia, A. Lasanta, and L. L. Bonilla
Phys. Rev. E 102, 042101 – Published 2 October 2020
At room temperature, micron-sized sheets of freestanding graphene are in constant motion, even in the presence of an applied bias voltage. We quantify the out-of-plane movement by collecting the displacement current using a nearby small-area metal electrode and present an Ito-Langevin model for the motion coupled to a circuit containing diodes. 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. However, there is power dissipated by the load resistor, and its time average is exactly equal to the power supplied by the thermal bath. The exact power formula is similar to Nyquist’s noise power formula, except that the rate of change of diode resistance significantly boosts the output power, and the movement of the graphene shifts the power spectrum to lower frequencies. We have calculated the equilibrium average of the power by asymptotic and numerical methods. Excellent agreement is found between experiment and theory.
Read more (paywalled): https://journals.aps.org/pre/abstract/10.1103/PhysRevE.102.042101
The researchers provided the following video simulation of their device;
Unfortunately nobody put a big sheet of graphene in my Santa sock, so I cannot test one of these free energy batteries for myself, and I don’t have access to the full paper.
But as an amateur electronics enthusiast, something immediately jumped out at me. The description of the physical structure of their graphene “battery” looks a lot like a resonant circuit.
If you touch one terminal of an oscilloscope, or a very sensitive volt meter, the device consistently registers a small AC voltage in your body. This electric field in your body is induced by fields created by the electric wires in the walls, the devices in the room, and the power lines in the street.
Other sources also contribute in a small way. The sun emits a lot of radio waves, as does commercial radio, TV, satellites, mobile phones, computers – there is a long list of potential sources.
This stray voltage is harmless to people, undetectable except with sensitive electronic equipment. But in larger structures the induced electric field can be significant. It can even cause severe damage to metal framed buildings, by triggering electrolytic corrosion.
Sensitive resonant circuits can amplify these tiny electric fields, allowing the oscillating electric field to build until the voltage is sufficient to overcome the voltage drop of the rectifier diode, and deposit a packet of charge into their capacitor (see the simulation above). This is the principle of operation of a crystal radio.
Crystal radios are primitive radio receivers which draw the electricity required to operate them from the received radio signal.
If you look at the circuit diagram of a crystal radio (below), it looks remarkably similar to the circuit of the brownian motion battery described in the video (above).
It is not clear from the abstract whether the scientists attempted to shield their graphene batteries from these ubiquitous stray external electric fields, and I do not have access to the full paper. But even if they made an attempt to shield their battery, I’m more inclined to believe that what the researchers accidentally built was very sensitive stray radio voltage detector, rather than a miraculous violation of the second law of thermodynamics.
How could scientists test whether their “battery” is really just a sensitive receiver of ambient radio signals? Very simple. Try attaching an antenna and ground, like the crystal radio circuit above, and see if their free energy device picks up a stronger signal.
Update (EW): Peta of Newark suggests an even simpler explanation, acoustic vibrations – they built an electret microphone.
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Surprised that so many people bothered to comment on this nonsense so l thought I’ll join in the crowd.
First you have to say the magic word. Oh, sorry, I see you did. never mind.
Would someone please change that secret word?
Yep, this has a lot of commonality with an electret microphone. If you’ve worked with microphones, you’ll know that the smaller the microphone, the more noise it produces since air is composed of molecules and what we call pressure is the average momentum exchange of the random collisions of molecules with the walls, or in this case the microphone diaphragm. Once you get down to the scale of the mean-free-path (about 70 microns at STP), individual collisions can be resolved with an average frequency of around 7GHz. Put a couple of diodes in the circuit that can handle this frequency and you’ll get power out.
In fact, if you have any wave, and you have the right sort of diode, you can get power from that wave.
Conservation laws are produced (such as 2LoT (2nd Law of Thermodynamics)) when we have symmetries (Noether’s Law), and if you can break that symmetry then that law no longer applies. For over 150 years we’ve known that 2LoT always applies and can’t be violated, but it’s only fairly recently that we’ve been able to manufacture diodes that are sensitive enough and work at a high-enough frequency to actually work at the required frequencies and voltage-offsets. Thus using MIM diodes attached to a nantenna can now receive and rectify IR radiation (and even green light), and even MIT have produced nantenna arrays that work. The reason you’re not seeing these in use is that they are expensive to make, the actual power produced at room temperature is pretty small, and also that they wear out pretty quickly (around 3 months or so before the 2nm of NiO in the tunnelling gap in the MIM diode fails through too-high a current density shifting the atoms around). Though they do actually work, the power produced simply costs too much relative to almost any other method (and of course making it uses more energy than you’d get from it in its lifetime).
Kinetic energy is defined as a scalar. However, it cannot exist on its own, and is always carried by a particle (here I’m treating a photon as a particle). Thus that particle has momentum, and that momentum defines in what direction the kinetic energy acts. If you only consider the kinetic energy itself, and don’t consider the direction it acts, you’re missing something important. Work is also considered as a scalar (same dimensions as energy), yet it is defined as force times distance, and that distance must have a direction included, so in fact work is a vector. Heat is kinetic energy carried by particles with an average momentum of zero, but where each particle has a definite direction. If you could change some or all of the directions of those particles to be in the same direction, the total momentum would be in one direction, and instead of heat you have a wind. We know how to get energy out of a wind.
In order to change the direction of a particle, without changing the total energy it contains, we simply need a field. This is after all how we recognise that a (conservative) field exists – it changes the direction of a particle without changing its total energy (KE+PE). Thus one way of getting energy directly from heat (without needing both a hotter and cooler heat-sink) is to use the photoelectric effect to produce an electron and hole in the depletion zone of a PN junction of a semiconductor that has a low-enough bandgap. The photoelectron and the hole are accelerated in opposite directions by the electric field, and the junction produces power. Basically, a solar panel with a low-enough bandgap to convert long-wave IR. These also exist, using a Mercury-Cadmium alloy, Tellurium-doped, with a bandgap of around 100meV (MerCaT sensors). Since this is tricky to make, with the consistency of a banana, they cost a lot (around $1500 for a chip of around 0.5mm²), and are normally used at LN2 temperatures to avoid them generating too much power from their own internal heat and not being sensitive enough to incoming IR. Very expensive if you want to power something from them, and of course the power per m² is very small too, but it does show that 2LoT can be violated.
There are a few other methods of violating 2LoT around. The common factor with all of them so far is that they cost a lot and produce a very small amount of power.
This “electret microphone” idea thus works because the scale has been reduced to comparable to the mean-free-path of the air molecules, and because at that scale you can resolve the individual collisions of molecules, and because you have diodes in the system that break the symmetry. The difficulty of making it, and possibly breakdown of the diodes after a fairly short life, probably means that you won’t see a commercial product based on this though. It may however lead to a few people reconsidering 2LoT, and to realise that if you get the scales right and deal with the particles that carry the kinetic energy rather than regarding heat as a pure scalar quantity, then 2LoT can be violated.
Why not use a Sterling Motor to move a generator ? 😀
Places with temperatur differences will be to find 😀 In case of doubts, ask a “climate scientist” 😀
If this is real why are they not doing it instead of talking about it? Just start producing all this free energy and sell it? Oh, yeah, not real.
Assuming that the energy is just being picked up from the environment (obviously most likely) couldn’t the tech still be of some use? Getting a little current from from otherwise lost electromagnetic energy is still current.
“Peta of Newark suggests an even simpler explanation, acoustic vibrations – they built an electret microphone.”
Won’t do very well then when we go back to the dark Ages-
Coronavirus lockdown reduces UK ground motions – BBC News
Next!
Regardless of the source of the lattice vibrations creating the current – thermal, electromagnetic or acoustic – there is no violation of the Second Law. Energy flows from high levels to lower, with some lost doing work along the way. Full stop.
The real trick with this kind of thing is packaging enough surface area to do anything meaningful and then maintaining an energy gradient large enough to make it work efficiently.
They could have resolved the electromagnetic or acoustic source by simply attaching the device to a spectrum analyzer rather than a capacitor. I’m surprised the peer reviewers didn’t pick up this obvious flaw. But then the authors would not have achieved fake news stardom and more grants to come, would they.
IMHO, the old adage “don’t feed the trolls” should be observed by scientists as “don’t feed the clickbait prostitutes.”
About that animation….
While positive and negative “charges” are useful in semiconductor theory (as electrons and holes), wires generally just use free electrons.
The animation shows positive charges moving through the wires. That is so painful to watch that I strongly recommend any EEs not watch the animation and just move on.
That alone would have dissuaded me from writing a post about this phenomenon.
BTW, this year is the 50th anniversary of debunking polywater. https://www.sciencenews.org/archive/sweat-their-brow
Oh yeah, this isn’t much better:
It wouldn’t be so bad, but the first network news story about “high” temperature superconductors claimed something like “The scientists were successful because they used liquid nitrogen instead of the colder liquid helium.”
Ya know, if they just kept the AC they could have run it through a transformer and gotten 120 volts. If they talked loud enough.
hmmm….energy from Brownian motion…..sounds like it might work about as good as those Crookes radiometers with their black-one-side-white-the-other paddles. Which actually work, just not economically…..
Here is my question, please tell me what is flowing? Positive charges? Positive charges imply protons. Unless they are into conventional flow showing positive charges despite the fact that is is the electrons (negative) flowing, I question their explanation.
It appears that they are attempting to harvest the changing electrical field occurring from the separation of the plates of a capacitor. The net effect is to increase the E field strength when the plates are close and then harvest that EMF created flow into a charge pumped capacitor. While entirely plausible in theory, that same EMF created by the small movement of the graphene also creates a back EMF restricting the movement of the sheet. While the Brownian motion is real, I am not convinced that at normal temps it is sufficient to generate a significant amount of energy. The energy harvested in their system would probably be temp dependent and much like a thermocouple able to provide a useable current at some temp. However, given the small motion seen at low temps this would probably very small in magnitude and difficult to detect.
Another issue is dielectric characteristics. At very small distances between the plates, even small microvolt charges could breakdown causing an internal short across the plates. They do not mention plate spacing or the amount, movement between the plates, or dielectric properties but I doubt that the voltage potential across the flexible dielectric can withstand a significant amount of potential. Many unanswered questions.
Where I was at school, Brownian movement was associated with absolute temperature and used in several exercises related to gas pressure.
We learned that, at constant temperature, mass and volume, there’s no energy that can be extracted out of such a system. Resulting in a brilliant demonstration on how cold and hot fronts can wreck havoc and dismantle wings when quicker warmer molecules encounter colder slower ones.
This entire graphene postulate is at best a flawed explanation of a thermal machine, the one that cools down when an electron is forced to flow in the circuit and needs to warm before another cycle.
Something Pelletier elements achieve with a much simpler setup.
Colloidal dispersions and emulsions show brownian motion. Just look at the fat particles in milk under the microscope. I doubt if graphine brings any magic to the party. Tiny particles, like molecules have thermal energy because their environment is warmer than absolute zero and therefore they vibrate.
I’m just off to charge up my car with this bottle of milk.
This has been an interesting diversion this morning. From the paper itself a couple of observations might be pertinent.
What, might one ask, is the temperature of a Brownian particle? Our notion of temperature depends on having a distribution, as temperature is simply a parameter in such. I think in this case they have applied something like measurements over a very long term measurement and numerical integration to take the place of the instantaneous ensemble. But this brings up the next point…
This involved numerical simulation of a very stiff set of equations which required pre-softening in order to integrate successfully.
Finally one might note two other things. First if the thermal bath is the source of supplied power, it must become colder as the circuitry runs, the cooler bath will draw heat flow from the surroundings. It’s a second-law machine! Heat energy flows around a circuit provided by energy drawn from a cold reservoir. It is a zeroth-law machine! Second, the extremely small power generated is of the order of picowatts. It will take tens of milliwatts before it can even act to trickle charge a cell-phone. Very small effects in the presense of a battery supplying potentially much larger power — a situation like Pons-Fleischman cold fusion where we are interpreting measurements at the limit of detection.
Kevin,
“This has been an interesting diversion this morning.”
As often happens on WUWT the diversions are most interesting!
There is not free lunch, and no perpetual motion machines. Like cold fusion, this will be shown to be an artifact of the experiment and not a real phenomenon.
Share value of graphene companies jumped last week here in UK , probably on the back of that , luckily I was too sensible
So build a pilot plant and show it works……..
Cold Fusion part X
“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. However, there is power dissipated by the load resistor, and its time average is exactly equal to the power supplied by the thermal bath.”
If the work rate (power) tends quickly to zero, this is not a “perpetual motion machine”, but merely the conversion of the heat energy of the thermal bath to electrical energy dissipated in the “load resistor”, which could be a short-life light bulb. If some external power source can keep the “thermal bath” warm, it could keep the light bulb on indefinitely, but in any case this is only Direct Current (not the Alternating Current used in electric motors). It would not be possible to run any rotating equipment or electric motors using this procedure.
Instead of hooking it up to a ground and an antenna, just do the experiment inside of a Faraday cage.
Maybe they discovered an infinite probability drive?
Replace hot cup of tea with graphene
WX,
Does that work on similar principles as Turboencabulator?
My wife’s hairdresser’s hair crackles & sizzles when immersed in water. She was shocked badly once and said it began then. Didn’t believe her, tbh, but then she proved it in front of us. So bizarre!
Probably has some Pop Rocks hidden in there.
“except that the rate of change of diode resistance significantly boosts the output power, ”
Since when can a passive component whose resistance changes “boost” the output power?