> There is no way.
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.
None of this matches the setup the paper describes, though of course you are right that bleeding heat into the Earth is a time-tested and known to function way to build such systems.
From the article:
> Before they understood what was happening, the researchers first thought that water was simply condensing onto the surface of the material due to an artifact of their experimental setup, such as a temperature gradient in the lab. To rule that out, they increased the thickness of the material to see if the amount of water collected on the surface would change.
There's a temperature gradient in their lab setup. i.e. one side of the material is cooler than the other side. This is where I extrapolated that you can increase the performance of the material by bleeding the heat into the Earth.