I’ve described in the last couple of blogs about the how we might make water and then how to grow plants in the desert. There are a few ideas that I thought might be able to add to the whole process, maybe increase its efficiency and scaling.
I’ve noted recently a lot of interest in thermal storage. One of these is salt based – as far as I can tell, it simply uses energy production from the water of hydration of a salt. If the salt is warmed with hot air, water is driven off and the air is cooled; if water is added, then heat is produced. This kind of system could improve the efficiency of a solar still which is the main method I have for producing water, by exploiting day time shifts in temperature. During the day, air from the outside would be passed through these batteries, heating them up with the colder (and slightly moist) air going into the cold side of the solar still; in the night, air moist air from the hot side could provide the water needed to discharge the batteries and keep the temperature up.
Of course, there is a limit to the size of the solar still that it would be plausible to build in the desert, but after the initial phase this would not be so necessary. Once there was enough vegetation, at least part of the desalination process, particularly the first pool and the final drying pans could be open air. While some of the moisture would be lost, much would be captured by the cooler areas created by the vegetation, essentially replicated the weather creation processes that we see in rain forest.
Finally, one nice way of increasing the amount of water vapour captured in this way would be to add some wind turbines downwind of the water. The lower pressure zone created by a wind turbine means that they tend to capture and condense water vapour, so would work synergistically with the vegetation.
Taken together these additions should allow expansion to the point that the only limiting factor is the speed at which water can be bought in, creating a managed but otherwise sustainable jungle in the desert.