Christophe68 wrote:...
There is no theoretical impossibility to directly convert heat (infrared radiation) into electricity. There is an almost inexhaustible source.
All that we know how to do now (thermal engine, photovoltaic cell, thermogenerator ...) requires a temperature difference between 2 "thermal baths". Thus, if your photovoltaic cell is at the temperature of the radiation that you receive, IR or not, it will no longer work. It is a consequence of the second law of thermodynamics. If it is false we wait for the demo, because so far we have no confirmed counter-example.
What we were talking about with Karpen's pile and the "Maxwell's demon" is precisely obtaining useful work from a single thermal bath, so with a process that cools the medium to draw energy from it, and with diminishing entropy. It would be a revolution, since the door is open to perpetual motion.
Exnihiloest wrote:I tried to duplicate the stack of Karpen, but it is impossible to rule out artifacts of the experiment (electrochemical reactions, reactions with oxygen in the air ...) so it was not inconclusive.
It's an interesting experience. An idea for voltage and current obtained?
It was in the order of volt (empty) and mA (shorted). These values are too strong, I certainly had chemical reactions. And then heating the solution should have increased the current, I checked that it was not the case.
For oxygen, why not place the battery in a closed bottle?
It does not remove oxygen. One solution: a vacuum pump. But the problem is much more complex than that. For example the metals of the electrodes have been able to absorb gases in their past, the water used too, so that it is very difficult to distinguish the weak current which would come from the Karpen principle of that much more probable of an electrolytic reaction. .