The disadvantages of the existing dry ice electromechanical pelletizers have been revealed. A schematic flow diagram of the new dry ice energy recovery pelletizer and a carbon dioxide TS diagram with the processes of the new pelletizer have been presented. The functions of the diameter of the piston expander of the new dry ice pelletizer and dry ice pressing pressure depending on the pressure of compressed gaseous CO2 have been derived. The optimal diameters of a piston expander for the dry ice pelletizer have been determined.