A turboexpander-generator unit , comprising: a casing with a gas inlet and a gas outlet ; a turboexpander having a turboexpander rotor mounted on a shaft supported for rotation in the casing ; an electric generator arranged in the casing and comprised of a generator stator and a generator rotor mounted on the shaft , for co-rotation with the turboexpander rotor ; a plurality of bearings configured and arranged for rotatingly supporting the shaft in the casing ; a main working gas flow path from the gas inlet to the gas outlet , extending through the turboexpander and the electric generator ; compressed working gas expanding in the turboexpander and generating mechanical power for rotating the generator rotor; and at least part of the expanded working gas from the turboexpander flowing through the electric generator and removing heat therefrom; wherein said bearings comprise gas-lubricated bearings, lubricated with said working gas used as lubrication gas; wherein the turboexpander rotor comprises an impeller comprised of a hub having a front surface and a back surface , and a plurality of blades extending from the front surface of the hub to respective blade tips; characterized in that the back surface of the hub faces the electric generator and the front surface of the hub faces the gas inlet ; and wherein the turboexpander comprises an outlet plenum , configured and arranged for collecting expanded working gas exiting the turboexpander rotor and fluidly coupled with a casing portion housing the electric generator ; the turboexpander-generator unit further comprising a side working gas flow path from the main working gas flow path to the plurality of gas-lubricated bearings ; and wherein a portion of the working gas passing through the side working gas flow path lubricates the plurality of gas-lubricated bearings . a casing with a gas inlet and a gas outlet ; a turboexpander having a turboexpander rotor mounted on a shaft supported for rotation in the casing ; an electric generator arranged in the casing and comprised of a generator stator and a generator rotor mounted on the shaft , for co-rotation with the turboexpander rotor ; a plurality of bearings configured and arranged for rotatingly supporting the shaft in the casing ; a main working gas flow path from the gas inlet to the gas outlet , extending through the turboexpander and the electric generator ; compressed working gas expanding in the turboexpander and generating mechanical power for rotating the generator rotor; and at least part of the expanded working gas from the turboexpander flowing through the electric generator and removing heat therefrom; wherein said bearings comprise gas-lubricated bearings, lubricated with said working gas used as lubrication gas; wherein the turboexpander rotor comprises an impeller comprised of a hub having a front surface and a back surface , and a plurality of blades extending from the front surface of the hub to respective blade tips; characterized in that the back surface of the hub faces the electric generator and the front surface of the hub faces the gas inlet ; and wherein the turboexpander comprises an outlet plenum , configured and arranged for collecting expanded working gas exiting the turboexpander rotor and fluidly coupled with a casing portion housing the electric generator ; the turboexpander-generator unit further comprising a side working gas flow path from the main working gas flow path to the plurality of gas-lubricated bearings ; and wherein a portion of the working gas passing through the side working gas flow path lubricates the plurality of gas-lubricated bearings . <EOS>