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Harvesting almost-unlimited energy (in tiny amounts) from ripples in graphene
(interestingengineering.com)
this post was submitted on 22 Aug 2023
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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.
I couldnt access the full text, but that was my impression, too, based on the summary. It appears to work on some analog of hysteresis where the technical balance of energy is maintained but the time scale of restitution is long enough that power can be "siphoned off". Again - since conservation of energy must be preserved and no matter is created or destroyed, this would serve to reduce the temperature of the graphene. There doesn't appear to be a scale for their experimental work and whether they're extracting pico amps or microamps across the (I guessing form the publicly available graphs) 0-0.4 volt potential.
It's not clear if they're looking at nominally uniform temperature material which has fluctuations in temperature due to the surroundings, or if they are inducing temperature gradients in the material intentionally to produce the signal. I'm an engineer, not a theoretical physicist, so anyone claiming to end-run the second law of thermodynamics is going to be treated with a bit of skepticism as to the practicality or scalability of this "cheat".
Wouldn't this just slowly cool the ambient temp around the material. I'm guessing there would be practical limits on how quickly this could create power but it doesn't seem to be claiming to create free energy just extract it from ambient Temps no?
This is exactly what it must be doing.
Graphene is above 0K -> the atoms have some thermal energy -> harvest some of that energy as electrical potential -> graphene cools down.
The most interesting application to me is that this could be use to remove heat at an interface without needing a thermal gradient to transport the heat.
I mean that depends on how quickly it actually cools down the ambient Temps no? Plus we still can't make massive sheets of graphene if I am not mistaken so wouldn't the scale of this make that impossible at this stage? I'd see the benefit for powering micro sensors via ambient Temps though.