Posted on 02/21/2022 11:11:46 AM PST by ShadowAce
FAYETTEVILLE, Ark. – A team of University of Arkansas physicists has successfully developed a circuit capable of capturing graphene's thermal motion and converting it into an electrical current.
“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,” said Paul Thibado, professor of physics and lead researcher in the discovery.
The findings, titled "Fluctuation-induced current from freestanding graphene," and published in the journal Physical Review E, are proof of a theory the physicists developed at the U of A three years ago that freestanding graphene — a single layer of carbon atoms — ripples and buckles in a way that holds promise for energy harvesting.
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.
In the 1950s, physicist Léon Brillouin published a landmark paper refuting the idea that adding a single diode, a one-way electrical gate, to a circuit is the solution to harvesting energy from Brownian motion. Knowing this, Thibado’s group built their circuit with two diodes for converting AC into a direct current (DC). With the diodes in opposition allowing the current to flow both ways, they provide separate paths through the circuit, producing a pulsing DC current that performs work on a load resistor.
Additionally, they discovered that their design increased the amount of power delivered. “We also found that the on-off, switch-like behavior of the diodes actually amplifies the power delivered, rather than reducing it, as previously thought,” said Thibado. “The rate of change in resistance provided by the diodes adds an extra factor to the power.”
The team used a relatively new field of physics to prove the diodes increased the circuit’s power. “In proving this power enhancement, we drew from the emergent field of stochastic thermodynamics and extended the nearly century-old, celebrated theory of Nyquist,” said coauthor Pradeep Kumar, associate professor of physics and coauthor.
According to Kumar, the graphene and circuit share a symbiotic relationship. 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.
That’s an important distinction, said Thibado, because a temperature difference between the graphene and circuit, in a circuit producing power, would contradict the second law of thermodynamics. “This means that the second law of thermodynamics is not violated, nor is there any need to argue that ‘Maxwell’s Demon’ is separating hot and cold electrons,” Thibado said.
The team also discovered that the relatively slow motion of graphene induces current in the circuit at low frequencies, which is important from a technological perspective because electronics function more efficiently at lower frequencies.
“People may think that current flowing in a resistor causes it to heat up, but the Brownian current does not. In fact, if no current was flowing, the resistor would cool down,” Thibado explained. “What we did was reroute the current in the circuit and transform it into something useful.”
The team’s next objective is to determine if the DC current can be stored in a capacitor for later use, a goal that requires miniaturizing the circuit and patterning it on a silicon wafer, or chip. If millions of these tiny circuits could be built on a 1-millimeter by 1-millimeter chip, they could serve as a low-power battery replacement.
The University of Arkansas holds several patents pending in the U.S. and international markets on the technology and has licensed it for commercial applications through the university’s Technology Ventures division. Researchers Surendra Singh, University Professor of physics; Hugh Churchill, associate professor of physics; and Jeff Dix, assistant professor of engineering, contributed to the work, which was funded by the Chancellor’s Commercialization Fund supported by the Walton Family Charitable Support Foundation.
They’re turning us into batteries, ala “The Matrix”. We can power our own electric cars, turning car pooling into a necessity!
The idea of limitless in this case is as long as the circuit is able to absorb thermal energy from it’s surroundings the current will flow indefinitely. Put a device such as this in a perfectly insulated box and thermodynamics dictates that as work is extracted via thermal motion of atoms in this case graphene that thermal energy is reduced thus cooling the device. As long as you are able to supply thermal energy from the ambient environment then the thermal vibrations will continue forever. Could be quite useful to power small sensors in remote places if they can store energy in a capacitor then you can use a graphene based ultracapacitor to drive a radio burst transmitter to send data to a remote receiver.
Tesla had a similar idea to use quantum vibrations to literally pull energy from the quantum vacuum. He didn’t use the terms quantum it was ethereal energy but same thing.
Pretty sure the crazy is what is unlimited.............
Thank you for sharing this story! However, please do so in a way that respects the copyright of this text. If you want to share or reproduce this full text, please ask permission from Innovation Origins (partners@innovationorigins.com) or become a partner of ours! You are of course free to quote this story with source citation. Would you like to share this article in another way? Then use this link to the article: https://innovationorigins.com/en/convert-waste-heat-even-with-small-temperature-differences-into-electricity/
Waste heat conversion to electricity even with small temperature differences
German and Japanese scientists have succeeded in taking a big step towards the goal of converting waste heat into electricity with small temperature differences.
13 January 2021
PETRA WIESMAYER
© IMT/KIT
Waste heat, such as from heating systems, usually just dissipates. It heats up basement rooms and their industrial surroundings unnecessarily without providing any benefit. However, a sustainable energy supply includes incorporating this waste heat into the energy supply. German and Japanese scientists have now come a big step closer to the goal of converting excess heat into electricity at low temperature differences.
In many technical processes, only part of the energy input is used. A varying amount of the remainder leaves the system as residual heat, which in turn could itself be used to provide heat or generate electricity if it did not go unused. The higher the temperature of this waste heat, the easier and more cost-effective it would be to utilize it. But there is also a way to use low-temperature waste heat, namely through thermoelectric generators that convert the heat directly into electricity. So far, however, this poses a problem: thermoelectric materials are expensive and sometimes toxic. Thermoelectric generators also require large temperature differences to achieve a relatively small effect.
Thermomagnetic instead of thermoelectric
But there is an alternative. As early as the 19th century, researchers introduced the first concepts for thermomagnetic generators. In the meantime, such generators, which are based on alloys whose magnetic properties are strongly temperature-dependent, represent a promising alternative to thermoelectric generators. In this case, the changing magnetization in an applied coil induces an electric voltage. The catch, however, is that the electrical output of these generators has so far left much to be desired.
Additional articles on the use of waste heat
Scientists at KIT‘s Institute of Microstructure Technology (IMT) and at Tōhoku University in Japan have now succeeded in significantly increasing the electrical output of thermomagnetic generators in relation to their footprint. “With the results of our work, thermomagnetic generators can compete with established thermoelectric generators for the first time,” says Professor Manfred Kohl, head of the Smart Materials and Devices research group at KIT’s IMT. “We have thus come much closer to the goal of converting waste heat into electricity at small temperature differences.” The team’s work is the cover topic in the current issue of the energy research journal Joule.
The vision: waste heat utilization close to room temperature
As thin films in thermomagnetic generators, magnetic intermetallic compounds known as Heusler alloys enable a large temperature-dependent change in magnetization and rapid heat transfer. This is the basis for the novel concept of resonant self-actuation, the researchers explained. Even with small temperature differences, the devices could be excited to resonant oscillations that could be efficiently converted into electricity, they said.
However, the electrical performance of individual devices is low, they said, and upscaling depends primarily on material development and construction. In their work on a nickel-manganese-gallium alloy, the German and Japanese researchers found “that the thickness of the alloy layer and the footprint of the device influence the electrical performance in opposite directions.” Based on this finding, they were able to increase the electrical output by a factor of 3.4 relative to the footprint. To do this, they increased the thickness of the alloy layer from five to 40 micrometers.
As a result, the thermomagnetic generators achieved a maximum electrical output of 50 microwatts per square centimeter with a temperature change of only three degrees Celsius. “These results pave the way for the development of customized thermomagnetic generators connected in parallel with the potential to utilize excess heat close to room temperature,” Kohl explains.
Cover photo: Thermomagnetic generators are based on magnetic thin films with strongly temperature-dependent properties. © IMT/KIT
Him: “Here...stick this in your yoo-hah.”
Her: “WHAT?”
Him: “It’s a dropcord, dummy. The car battery is getting low and we need to recharge it.”
All ready to build The Matrix
Interesting, but don’t hold your breath waiting for this to scale up to run your house.
From the article:
If millions of these tiny circuits could be built on a 1-millimeter by 1-millimeter chip, they could serve as a low-power battery replacement.
It's not meant to provide that much power. Just very low-power applications. the "limitless" in this case is not magnitude, but duration.
... along with snake oil that can cure cancer and bad breath.
...capturing graphene's thermal motion and converting it into an electrical current.
Thanks ShadowAce.
University PR department strikes again!
Violates second law of thermodynamics to extract work from thermal energy without dissipating heat to a lower temperature heat sink as well.
Look up “Maxwell’s demon” for an example of how subtle nature can be counterattacking these free work machine schemes. It will invoke quantum mechanics if it has to :) . In this case I think it will involve back EMF.
(Not criticising ShadowAce, criticizing the premise.)
My wife showed me an article where someone is playing with mice DNA to create bitcoin. I’m sure some scientist will figure out how to do so in humans. Soon we can be our own power and financial source.
Thermal to electrical. That is conversion, not creation and therefore not limitless.
How low? Cell phone low? Clock radio low? Time and temperature display low? What devices would find it a suitable power source?
Tesla would be very excited.
So, that’s why the vaccine, so-called, main ingredient is graphene oxide.
The energy has to be coming from something other than the random thermal motions. This probably amounts to a microscopic version of those old watches that you wind by shaking them.
Probably more than enough for sensors like this. The internet of things is looking at harvesting ambient radio waves particularly Wi-Fi and 4/5G signals to power sensor nodes. Since both of those signals are pretty much everywhere urban and suburban now.
https://www.power-and-beyond.com/ultra-low-power-technology-for-battery-less-iot-sensors-a-885246/
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.