Technology

I still think it's a pipedream. The energy needed vs what you get in return doesn't add up for me.

I would imagin they are similar to molecular sieves. They are very porous and that's how they trap the water. If it was easy to get out then it wouldnt trap water very well. To pull that water back out you have to really heat it up to force it to find its way out like a maze. If you where to say used black plastic, I have doubts you could get anywhere near boiling so it might be free an easy you wouldn't be putting enough energy in to get enough water out. So you would need an external power source. No matter where (magic solar panels).

If your going to use an external power source might as well use it to put a pump on a pipe and I would guess move an infinite more amount of water for the power used.

While trucking water would be expensive. I would imagen these would be even more so. You have to buy them move them set them up and im sure do some sort of maintains. And if you want a long term solution look no further than Las Vegas. Where a big pipe is cheap and easy, well compared to what I would imaging what this would cost at the same scale.

Also to my understanding many places do have some form of water but its not safe to drink. I would rather spend the money on a filter/ purification system of water than try to pull it out of the air that would still probably need to be filtered, dust is crazy.