This article gives analysis of the different designs of gas-dynamic bearings used in turbo-expander generators. It is shown that the best and most reliable bearings are flap gas dynamic. Application prospectivity of flap bearings in turbomachines compared with other types of gas bearings is stipulated by their increased resistance to self-excited oscillations in a wide range of rotor speed, low sensitivity to moisture and contamination of gas medium mechanical impurities. Prospective viability is also proved by zero wear of friction surfaces at high rotor speed, operation ability at the sudden change in temperature, low sensitivity to deformation of the housing, rotor distortions and deviations from the alignment of the bearing assembly, low complexity of manufacturing and machining accuracy, reliability, the ability to start and stop the rotor without compressed gas supply, large lifespan operation.