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
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?
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.
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.
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.