A machine for recovering power from a flow of compressed gas, for example, natural gas includes a turbo-expander having a turbo-expander wheel, and a generator having a rotor able to be driven by the turbo-expander wheel and a stator about the rotor. The turbo-expander and the generator are housed in a length of pipe. The turbo-expander wheel has an obverse side facing the generator. There is a flow passage for the flow of expanded gas that places the obverse side of the wheel in gas flow communication with an outer surface of the stator. This outer surface typically carries fins to facilitate cooling of the stator by expanded gas from the turbo-expander.