NOVELTY - Method for desalination of water involves: cooling amount of seawater (11) to phase which allows for clathrate formation; injecting dispersed clathrate-forming gas agent (12) into amount of seawater; imparting ultrasonic energy into amount of seawater; collecting clathrate crystals (13) from amount of seawater; and melting crystals to form amount of fresh water (29).    USE - For desalination of water that is seawater (claimed).    ADVANTAGE - The method provides improved method for desalination of seawater by clathrate formation, where method addresses cost, energy efficiency, and environmental concerns, by employing sonic energy to improve nucleation during clathrate formation. Further, advantage of using cyclopentane as clathrate-forming gas, is that clathrate formation occurs at sea level atmospheric pressures using readily attainable temperatures. The nucleation enhancing elements used thus allow for use of inexpensive and environmentally controllable cyclopentane as clathrate forming gas.    DETAILED DESCRIPTION - Method for desalination of water involves: cooling amount of seawater (11) to phase which allows for clathrate formation; injecting dispersed clathrate-forming gas agent (12) into amount of seawater; imparting ultrasonic energy into amount of seawater; collecting clathrate crystals (13) from amount of seawater; and melting crystals to form amount of fresh water (29). The method further involves augmenting amount of seawater with flow of additional seawater. The injecting occurs through gas diffuser (17) to create stream of bubbles of gas agent (18). The imparting of ultrasonic energy involves locating and activating ultrasonic transducer (21) within amount of seawater, particularly within the stream of bubbles of gas agent. The activating involves operating transducer at frequency of 30-50 kilohertz. The method further involves placing amount of solid material particles within the stream of bubbles of gas agent, and the method further involves carrying particles within structure mounted to transducer, where structure comprises array of apertures sized and shaped to contain particles and allow passage of portion of stream of gas bubbles through apertures. The collecting involves washing crystals to remove residual seawater from crystals. The melting involves using residual heat generated by compressor or chiller device (15) associated with apparatus. The cooling involves pre-chilling amount of cyclopentane by circulating it through conduit exposed to amount of chilled seawater. An INDEPENDENT CLAIM is included for clathrate freeze desalination apparatus comprising: crystallizer reaction vessel (10); amount of seawater located in crystallizer; source of clathrate forming gas; and ultrasonic transducer located to impart sonic energy upon amount of seawater located within vessel.    DESCRIPTION OF DRAWING(S) - The figure shows diagrammatic block diagram of major components of seawater clathrate formation system using cyclopentane as clathrate forming gas agent.    Crystallizer (10)    Flow of seawater to crystallizer (11)    Clathrate forming gas (12)    Clathrate ice (13)    Source of gas agent (14)    Cooling system/chiller (15)    Internal diffuser (17)    Bubbles of gas (18)    Controller (20)    Ultrasonic transducer (21)    Prewash brine filter (23)    Wash column (25)    Washed clathrate crystals (26)    De-crystallizer to melt clathrate crystals (28)    Fresh water (29)