Deserts are dry, but the air in them is not 100% dry. To take an example, in Morocco, the place called Merzouga is very dry, even though there is a lake and small oasiseses.
In the below graph you can see how that works : Right now the temp there is 26 degrees Celsius, the humidity is 16%. You start below at 26 degrees then you look for the curve for 16% humidity, then you go to the right to see how many grams of water the air contains. At this point it the air contains 0.004 gram water per gram of air. That means it contains about 4 grams of water per m3 (which weighs about 1.1 kg). Not a lot! Another way of looking at it is that the ‘dew point’ is at -2 Celsius, so 28 degrees lower than the actual temperature.
So in theory if you cool 1 m3 of air to -2 Celsius you will see 4 grams of water condense. So if you build a cooling mechanism that can harvest cold once condensation has taken place that will surely work great to get the water out of the air. You can increase the efficiency with an electric field as water is polar and will move in the field. It is a good question whether at high temperatures water really needs a lot of coaxing to separate out, or at least move to a region with higher humidity as the heat transfer is relatively small.
How would you cool the air? With wind power. There is a complete design for such a device from a dutch producer we wrote about already, but his plans where thwarted by ‘investors’ meaning banks that increase the price of the invention so it becomes impossible to deploy. This happens all the time Shell is a major company constantly sabotaging energy innovation for example.
We need devices like the Dutch Rainmaker if we want to aforest the desert. They are cheap and efficient, the parts cost about 10.000 Euro, not too much one would say. Companies that worked on this in 2012 have since folded or been bought up. But it can still be done. The challeng is to achieve the same effect but with the least amount of resources and overhead. Anyone that designs a breakthrough in this field will be responsible for more life to exist in the desert.
Cloud seeding can be done with any type of dust, preferably charged though. Salt is fine. They used to be dropped from fuel guzzling heavy planes, but these days there are electric drones, even ones that can loiter for hours on solar energy. China actually managed to do it.
UAE “The country does, though, “have plenty of clouds”, so the plan is to persuade the water droplets in them to merge and stick together, “like dry hair to a comb” when it meets static electricity, he said.”
“The radar-controlled drone dispersed silver iodide into clouds to convert ambient moisture into rainfall. Relative to traditional equipment such as cannons and manned aircraft, drones can reach higher altitudes, have a longer range (they can run for more than 10 hours), are suitable for operations in complex weather conditions, and are more efficient, cost effective and safer” But silver can’t be wasted endlessly