If for some reason (I don't know, heating a blimp perhaps?) you were restricted to an air-sucking heat pump you could go wild and route the intake (or some frac

If for some reason (I don't know, heating a blimp perhaps?) you were restricted to an air-sucking heat pump you could go wild and route the intake (or some fraction of it) of the heat pump through the generator and motor: this should recapture all the losses. A worthless optimization since the waste avoided would be free (just build a slightly larger turbine), but technology for low intensity heat is uniquely simple, but why not use three opportunity to make it amazing ("conversion losses? Yeah, they are taken care of")