Abstract: A cryogenic oil-free direct drive turbogenerator for gas liquefaction plant applications is described. The pressure energy from cryogenic gas is expanded through a turbine and the power generated is converted into electricity through a directly driven generator and a power electronics arrangement. The machinery can withstand very cold temperature operation (e.g., <?425° F.) by isolating the cold turbine side from the warmer side of the machine turbine end and has a hermetically sealed design wherein the process gas is fully contained from leaking at operating pressures. A unique gas injection scheme uses seal gas segregation, thrust bearing cooling and pressure balance for thrust control which is accomplished through a pressure regulator arrangement. Also described is an algorithm for speed control and overspeed protection through the power electronics system. The rotating components of the turbogenerator are supported on foil gas bearings for oil-free operation eliminating extraneous lubrication.