The growth in demand for water and increasing shortages of supply are two of the most certain scenarios of the 21st century. Agriculture, accounting for some 70% of all water used, is a major pressure point. Fortunately, the world is not short of water, it is just in the wrong place. The Seawater Vertical Farm uses seawater to cool and humidify greenhouses and to convert sufficient humidity back into fresh water to irrigate the crops. It is set in Dubai where the lack of fresh water and of local vegetables, the awful urban traffic, the transport problem and the high soil value makes realistic the idea of using some urban plots for intensive cultivation. The design of the Seawater Vertical Farm is quite simple. It provides for five cocoon-greenhouses fixed to five branches that also transport and nebulize the seawater creating a humid and cool flow, ideal for the plants, like the environment of the equatorial forest. In these conditions crops need very little water as they are not stressed by excessive transpiration.

As the air leaves the growing area it passes through the second evaporator which has seawater flowing over it. During this phase the humid air mix with the warm dry air of the ceiling interspace. Thus the air is made much hotter and more humid. No fans are required: the warm air is forced by the stack effect to flow upward through the central chimney. Here the warm and humid air will condense when in contact with plastic tubes where cool sea water is pumped. In the surface of the condensers drops of fresh water will appear, ready to be recollected in a tank to water the cocoon-greenhouses and for other uses. The seawater evaporators are made of cardboard sheets, cheaper and surprisingly effective. They crystallize calcium carbonate from the sea water and harden like sea shells. The process is controllable and the results indicate that the life of the evaporators can be extended almost indefinitely.