I'll throw in one comment on losses. If you run an alternator like you said, the HP used to spin the alternator to drive the electric pump (and fan?) will be very near equal to the HP used to spin the belt driven water pump and fan, provided your fan has a working clutch. You're applying energy to get rid of heat and it's going to take the same energy whether you're belt driven or electric motor driven. There's no free energy source in an electric motor.