

Can graphene harvest energy from thin air? - rpm4321
http://www.cnn.com/2014/12/23/tech/innovation/tomorrow-transformed-graphene-battery/

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opless
I thought we obeyed the laws of thermodynamics here?

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gus_massa
There is a lot of Oxygen and a tiny tiny tiny amount of Hydrogen in the air.
It's in not equilibrium, so they "burn" slowly and "produce" some energy
following the first and second thermodynamics law. Dew to the second law, part
of that energy has to be dissipated as heat, and only a part can be
potentially harvested in a useful form like electricity.

The idea is to harvest that energy, to do that they use the graphene membrane
as a part of a device that separate the Hydrogen. The separation requires that
some additional energy is dissipated as heat, because of the entropy
requirements of the second law.

If they can get more useful energy "burning" the separated Hydrogen than the
energy necessary to separate the Hydrogen, then they get a useful device. I'd
have to do the calculations using the concentration of the Hydrogen in the
atmosphere, but I'm too lazy.

I guess that this is theoretically possible is you use the maximal efficiency
in each and every step, but in the real word the efficiency is much lower and
you get no useful energy.

I think there is a little hope that this can be useful with industrial fumes
that have more Hydrogen to separate the contaminants, but the application with
air is only a linkbait or a grantbait.

