Heat recovery steam generator. A heat recovery steam generator (HRSG) is an energy recovery heat exchanger that recovers heat from a hot gas stream, such as a combustion turbine or other waste gas stream. It produces steam that can be used in a process (cogeneration) or used to drive a steam turbine (combined cycle). An example of an ideal candidate that utilizes a HRSG is a university. Universities are ideal for HRSG applications because they can use a gas turbine to produce high reliability el