The invention relates to a desalination method and system that uses freeze crystallization technology that incorporates the use of compressed air energy as the source for freezing temperatures. When compressed air is released by a turbo expander, chilled air is produced as a by-product, wherein the chilled air is introduced into a crystallization chamber. Also injected into the chamber is a spray cloud of seawater droplets, which has been pre-chilled by heat exchange with the cold chamber walls, and which is then circulated and exposed to the chilled air in the chamber. The sizes of the droplets can vary, but are preferably predetermined, along with the relative temperatures, flows and speeds of the spray and chilled air, such that when the droplets are circulated within the chilled air, and settle at the bottom of the chamber, they are deposited at slightly above the eutectic temperature. This way, the ice/snow mass that forms at the bottom of the chamber will consist of frozen ice crystals, and a residue of salt water brine, which can runoff from the mass, either from the sides, or through any voids or channels that may form within the mass.