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Harvesting almost-unlimited energy (in tiny amounts) from ripples in graphene (interestingengineering.com)

submitted 1 year 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 6 points 1 year ago* (last edited 1 year ago) (3 children)

That's actually a big deal, thermodynamically. They are claiming that they can reduce entropy essentially without an input or pump - their diode aray appears to be a Maxwell's demon.

[–] SmoothIsFast@citizensgaming.com 3 points 1 year ago (1 children)

I mean isn't the graphenes physical vibrations the input/pump in this situation powered by the ambient thermal energy radiating into the graphene? I'm only a software engineer so I apologize if some of this is just going over my head lol.

[–] Overzeetop@sopuli.xyz 3 points 1 year ago* (last edited 1 year ago)

Hey, I'm just an aero/structural engineer - this microscopic and quantum level stuff is well outside of my daily practice, too. The theory (of which I am innocent of all detail) says that this shouldn't be possible - using Brownian motion as a source (directly or as a pump). If this is an end-run around classic physics, that's okay, as long as the overall energy balance can be shown to be maintained.

Edit: Usually in threads like this I hope to say something wrong, or apply the wrong principle, and then someone who is an expert comes in and corrects me. Then I go look up whatever it is they say and I get to learn something new for the day. Either that or someone who knows more than I do agrees with me and expands on the description in a really insightful way, and I get to learn something more in depth that day.

[–] SmoothIsFast@citizensgaming.com 2 points 1 year ago

I guess in addition isn't the thermal gradient they are claiming is nonexistent just extremely small throughout the graphene molecules? They aren't gonna be a perfectly uniform temperature and thermals don't transfer instantly meaning a gradient would be present. I guess couldn't you prove they aren't reducing entropy by comparing how quickly the sheet of graphene cools when this system is active vs a regular sheet of graphene in the same conditions. I'd guess we would see their system losing heat more quickly than the plain old sheet of graphene thus showing this isn't a maxwell demon?

[–] Feathercrown@lemmy.world 2 points 1 year ago

Oh that's what this was reminding me of! Thank you.