how can graphene capture usable en energy from brownian motion without violating the second law of thermodynamics?
In: Physics
It can’t really. The energy it captures is so miniscule that it isn’t really useable for anything. We’re talking picowatts of power.
The reason it isn’t breaking the laws of thermodynamics is because everything has energy in the form of heat. Graphene moves enough just with that ambient heat that it can be designed so that it can generate a voltage potential.
Similar mechanisms have been tried with microscopic ratchets and other things. The graphene thing is unique though in that you directly get electricity out. But basically what happens is that when you get energy from the brownian motion the disorder in the system increases until it hits a limit beyond which everything is too disordered to generate more energy.
The source of power is essentially the actual manufacturing of the thing in the first place.
Think of it like an ice cube. When an ice cube melts (and becomes more disordered) it absorbs heat from the ambient atmosphere, and if you are clever you can harness some of the transfer of heat and turn it into power (like with a thermoelectric generator).
But at some point the ice cube is going to have melted and you have to freeze a new ice cube.
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