The article is quite vague. I assume they’re saying that a humidity difference drives a net flow of water vapor through their machine. So you seal one side and

The article is quite vague. I assume they’re saying that a humidity difference drives a net flow of water vapor through their machine. So you seal one side and stick something hygroscopic in it as a big humidity sponge and expose the other side to the atmosphere. Then, about twice a day, you get a current if your climate has large diurnal humidity changes.