Physicist’s Innovation Generates Clean, Limitless Power from Graphene
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, 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.
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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.
Story Source:
Materials provided by University of Arkansas. Original written by Bob Whitby. Note: Content may be edited for style and length.
Journal Reference:
- P. M. Thibado, P. Kumar, Surendra Singh, M. Ruiz-Garcia, A. Lasanta, L. L. Bonilla. Fluctuation-induced current from freestanding graphene. Physical Review E, 2020; 102 (4) DOI: 10.1103/PhysRevE.102.042101
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Tom O
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I think I can believe in magic before I can believe this is legitimate. In fact, IF I believe in this, it is the same thing as believing in magic, just without Merlin around to cast the spell. This sounds like energy from nothing.
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Joseph Olson
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this is milliwatt power at millivolt power….i had the great pleasure of hearing a lecture by R Buckminister Fuller in college, +/-1971. The inventor of the geodesic dome predicted six sided Carbon graphine sheets, nanotubes and spherical “Bucky balls” which all happened a decade later.
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Josh
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Not from nothing, from thermal energy. What’s the problem?
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D. Boss
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Exactly, this harvests thermal energy from the environment (the room), so it’s not earth shattering. Nor is it very practical – micro watts to maybe milli watts, and for now requires superconducting inductor. So until you have room temperature superconductors, it takes way more energy to drive this thing than it harvests….
Yes, it’s way cool that they have done this – but it’s little more than a curiosity at this stage.
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Charles Higley
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Just like a perpetual motion machine, it cannot be done. A machine is by definition capable of doing work and, as soon as a machine starts doing useful work, it starts to lose energy. SO, along the same line, clean limitless power is impossible as it has to come from somewhere and energy conversions ALWAYS have losses. Local thermal energy simply cannot be harnessed to do meaningful work. I have a watch that runs a on solar cell, and that’s about all this will be useful to do.nThey might have an efficient energy conversion idea but limitless energy, NO. It would be challenge to run a can opener with such a low wattage thermally-driven device.
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