A hydraulic energy source for supplying a downstream hydraulic system with hydraulic energy. In particular, a hydraulic system for controlling and/or cooling a transmission preferably a dual clutch transmission. The hydraulic energy source enables a first partial volume flow which is produced at a comparatively high system pressure and which is used to supply an actuator of the hydraulic system and a second partial volume flow which is produced at a comparatively low cooling pressure and which is used to cool the hydraulic system, to be produced The hydraulic energy source has an electrically driveable first volume flow source which is used to produce the first partial volume flow and a second volume flow source which is used to produce the second partial volume flow. The second volume flow source is drivingly connected independently of an internal combustion engine.