this post was submitted on 22 Aug 2023
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Harvesting almost-unlimited energy (in tiny amounts) from ripples in graphene (interestingengineering.com)
submitted 2 years ago by will_a113@lemmy.ml to c/science@lemmy.ml
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Scientists have figured out how to harness Brownian motion -- literally the thermal energy of individual molecules -- to make electricity, by cleverly connecting diodes up to pieces of graphene, which are atom-thick sheets of Carbon. The team has successfully demonstrated their theory (which was previously thought to be impossible by prominent physicists like Richard Feynman), and are now trying to make a kind of micro-harvester that can basically produce inexhaustible power for things like smart sensors.

The most impressive thing about the system is that it doesn't require a thermal gradient to do work, like other kinds of heat-harvesting systems (Stirling engines, Peltier junctions, etc.). As long as it's a bit above absolute zero, there's enough thermal energy "in the system" to make the graphene vibrate continuously, which induces a current that the diodes can then pump out.

Original journal link: https://journals.aps.org/pre/abstract/10.1103/PhysRevE.108.024130

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[–] Overzeetop@sopuli.xyz 22 points 2 years ago (22 children)

This is not a source of energy, but it could be used two ways:

  1. By applying thermal energy you can extract electricity.

  2. By not applying thermal energy, this might be used to supercool things (like electronics, or to make helium flow as a superfluid).

The potential here (ha!) is that power May be extracted without being concerned about Carnot efficiency limits, at least on a very small scale.

[–] will_a113@lemmy.ml 22 points 2 years ago (19 children)

It's more like a generator that uses ambient heat as the "battery". With previous systems you could only extract useful work from heat if you had a heat gradient (e.g. one area that's hotter than another). With this invention the innovation is that graphene's unique combination of thinness and conductivity basically let you convert the brownian "heat" of the substance itself (not the environment) into electricity.

[–] rastilin@kbin.social 7 points 2 years ago* (last edited 2 years ago) (1 children)

This is genuinely incredible though. Because it means you can cool things even when there's nowhere to dump the heat into, for example, space.

EDIT: Though in space you lose heat as infra-red, but only in limited amounts. Scaled up this technology would allow far better control letting you run more powerful equipment while also improving efficiency.

[–] Overzeetop@sopuli.xyz 2 points 2 years ago

And you're limited to approaching 2.7K, the background temperature and limit for radiative cooling, which is higher than you would want for some sensors. Being able to either extract power and charge a battery to be either used as power, to heat other parts of the craft, or to concentrate for more efficient radiation would be quite useful.

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