"A typical trap, with a 40-square-metre collecting area, yields about 200 litres a day. That is enough to supply around 60 people with drinking water. Such a collector costs $1,000 or so, and will last a decade."

To me that sounds cheap already. 13c/month/person. $1.37/m3. I pay more than that per m3 (Sweden).

To scale things up for agriculture or forests, I would assume a more industrial scale for the whole thing would make more sense. Feels like it could lead to an order of magnitude in lower cost - mainly because $1000/40m2 seems expensive. Growing forests in the desert using fog-water... could it be something for Elon's carbon capture contest? I don't know about relevant data points to make the calculations - how much water do you need to grow a forest in a desert? How much co2 does a forest capture when "completed"? How much time does that take?