I'm not aware of any passive, solid state dehumidifiers which are not chemical, which condense water to a chemically loaded solution, which what a Windtrap is not.
So, even though it may not be 100% clear how from their description, their device is nothing but a novel way of making a dehumidifier that needs some kind of active component - perhaps the AC that is keeping the temperature steady in their experiment (since water condensation generates large amounts of heat, it's likely that, without the AC, temperature would rise and their water droplets would evaporate right back).
No, there's a way without running afoul of thermodynamics. You need to bleed the heat to a cooler surface efficiently, and you can do it without any external power.
You can use heat pipes to effectively wick away heat to a heat sink, like the Earth itself. Similar systems exists for cooling and heating, which uses buried pipes to extract or dump heat to the Earth's crust. You can sink the heat similarly without any external power (sans wind to push air through the material).
In the Windtrap example, the other side of the opening is a deep well basically. Cooler than outside world. The rocks sink the heat probably, too. Sı it's possible to create self-sustaining process without external electricity. Yes, an heat-pipe is not solid-state per se, but it's insulated and works on the principle of heat difference only.
> their device is nothing but a novel way of making a dehumidifier that needs some kind of active component...
No, their paper say that they forced air through it and it worked on a temperature differential. Maybe a compressor or Peltier device can acclerate the process, sure, but sinking the heat to the earth and blowing air through it will work equally well.
Have a friend who designs heat-pipes for space applications. That things are way faster than we see on computer applications, but equally more expensive.
