you could produce electricity using the engine's heat by utilizing peltier plates.
VirtualVillage.com i've got two 12v 400w plates on the way, i just have to find a spot that gets warm but doesn't exceed the plates max temp and mount them with some thermal grease somehow and put a heatsink/fan on the otherside to cool down the cold side. Not only does using the engine's wasted heat to produce it's electricity increase the overall efficiency of the engine but could possibly completely replace the alternator. Just gotta make sure to put a diode in the line so that when the temperature gradient is gone they don't become heat pumps.