Condensation of water is exothermic. If you add a cold thing to the environment, ie, remove heat from the water, the water will condense all on its own. This reaches steady-state when the cold thing is warm and the water is condensed. No thermodynamics issue!
They’re claiming they have a material that will do it at higher temperatures. Assuming such a material gets hotter as it works, there’s no thermodynamics problem here.
> They’re claiming they have a material that will do it at higher temperatures. Assuming such a material gets hotter as it works, there’s no thermodynamics problem here.
That's ok, but the amount of water you get is fixed - the process can't continue. You install the device into your room, it condenses 1L of water as droplets on its surface (or, more likely 1ml of water), and it's now done, that's all the water it's going to remove/produce, if this is the right explanation. It would be perfectly equivalent to bringing in a cold slab of metal from your fridge into your room - it will condense some water as it gets hotter, and it will eventually get as warm as the room and stop condensing anymore water, forever.
Conversely, if the process were continuous (say, as long as you remove the condensed droplets, new droplets form), as they seem to claim, that would very likely violate thermodynamics again.
What about entropy? The reason you need to power AC for example is that if you didn't you could reduce entropy and generate power for free, and basically reverse time.
The amount of entropy in a closed system is not allowed to decrease, but it is allowed to be constant. The amount of energy released by the phase shift is equal to the amount of energy absorbed by the object as heat.
Sure, but then the temperature of the object has to increase. And as its temperature increases, it has to stop condensing water - at the very least, once it reaches ~100C, it will instantly boil off any extra water that it condenses.