A turbo economizer adapted to be used in a chiller system includes a nozzle, a turbine, and an economizer impeller. The nozzle introduces refrigerant into the turbo economizer. The turbine is disposed downstream of the nozzle, and the turbine is attached to a shaft rotatable about a rotation axis. A flow of the refrigerant introduced through the nozzle drives the turbine to rotate the shaft. The economizer impeller is attached to the shaft so as to be rotated in accordance with rotation of the shaft. In the turbo economizer, the nozzle reduces a pressure of the refrigerant such that a pressure of the refrigerant entering the turbo economizer is lower than a predetermined pressure, at least some of the refrigerant passes through the nozzle is introduced into the economizer impeller, and the economizer impeller increases a pressure of the refrigerant introduced thereinto to the predetermined pressure.