Guest essay by Eric Worrall
A meme is circulating on the Internet about graphene batteries that provide unlimited free energy and are obtained from the random Brownian motion of the graph. But there is another possible explanation that researchers may have overlooked.
Physicists have just shown that graphene circuits can produce clean, limitless energy
OCTOBER 6, 2020
Scientists have been able to draw electricity from the thermal motion of graphene at room temperature, potentially providing us with a clean future source of limitless energy for small devices.
The approach cleverly takes advantage of both the nanometer-sized ripple and Brownian motion – the random movement of particles – found in graphene and creates an electrical current that can be used for a variety of purposes.
“A graph-based power generation circuit could be built into a chip to provide clean, unlimited low-voltage power to small devices or sensors,” says University of Arkansas physicist Paul Thibado.
The research builds on previous work from the same lab that showed free-standing graphene curls and kinks in ways that can be harnessed for energy.
“The origin of these nanometer-sized waves is still open“The team writes in their study, noting that the graphene waviness appears to be due to subatomic particle interactions in the material.
A crucial part of developing their system was the use of two diodes in the circuit to convert the original alternating current (AC) to direct current (DC). This allowed the current to flow through the circuit on separate paths in both directions.
Read more: https://www.sciencealert.com/physicists-build-a-circuit-from-graphene-that-generates-clean-limitless-power
The summary of the paper;
Fluctuation-induced current from free-standing graph
PM Thibado, P. Kumar, Surendra Singh, M. Ruiz-Garcia, A. Lasanta, and LL Bonilla
Phys. Rev. E. 102, 042101 – Released October 2, 2020
At room temperature, micrometer-sized foils made of free-standing graphene are in constant motion, even when a bias is applied. We quantify the out-of-plane motion 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 heat and work rates of stochastic thermodynamics quickly approach zero. However, the load resistance consumes energy and its time average is exactly the same as the power delivered by the thermal bath. The exact power formula is similar to Nyquist’s noise power formula, except that the rate of change in the diode resistance increases the output power significantly, and the movement of the graph shifts the power spectrum to lower frequencies. We calculated the equilibrium average power using asymptotic and numerical methods. There is excellent agreement 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 has put a large sheet of graph in my Santa Claus sock, so I cannot test one of these free energy batteries myself and have no access to the full paper.
But as an amateur electronics enthusiast, I immediately saw something. The description of the physical structure of your graphene “battery” is very similar to a resonance circuit.
When you touch a connector on an oscilloscope or a very sensitive voltmeter, the device consistently registers a small alternating voltage in your body. This electrical field in your body is induced by fields created by the electrical wires in the walls, the devices in the room, and the power lines in the street.
Other sources also contribute to a small extent. The sun emits many radio waves, as do commercial radio, television, satellites, cell phones, and computers – there is a long list of potential sources.
This stray voltage is harmless to humans and can only be detected with sensitive electronic devices. In larger structures, however, the induced electric field can be significant. It can even cause severe damage to metal-framed buildings by triggering electrolytic corrosion.
Sensitive resonance circuits can amplify these tiny electric fields so that the oscillating electric field can build up until the voltage is sufficient to overcome the voltage drop of the rectifier diode and deposit a packet of charge in its capacitor (see simulation above). This is how a crystal radio works.
Crystal radios are primitive radio receivers that draw the power required for their operation 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).
Crystal Radio Circuit. By Chetvorno – Own work, public domain, link
The abstract doesn’t make it clear whether the scientists tried to protect their graphene batteries from these ubiquitous external stray electrical fields, and I don’t have access to the full paper. But even if they tried to shield their battery, I tend to believe that what the researchers inadvertently built was a very sensitive leakage 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 easy. Try connecting an antenna and ground like the crystal radio circuit above and see if the free energy device gets a stronger signal.