[duplox]

I don't think you'd want to use a steam engine, it takes up much to much space and the entire purpose of a pressurized cooling system is to keep the water from turning into steam. There are other engines that run off of heat exchange, I forget the name of them at the moment. One idea I had was to use the heat to drive a water pump, so you'd pretty much have a self contained cooling system. Another interesting result of using a system like this is if the engine is cold, no coolant will circulate. When its semi warm, coolant will circulate slowly, hot, faster etc. Eventually it'll reach a balance between the radiator's efficiency and how much heat the engine is dumping into the cooling system, and temperature would stabilize. There is a problem that with different outdoor temperatures, the efficiency of the pump would alter(more efficient when its cold, less when its hot), so you wouldn't have the precision of a thermostat for keeping temperatures exactly at 180* regardless of outside temperatures. An idea to get around this is to use a tstat as almost a wastegate for the water pump's "engine". Considering nearly a third of the energy an engine produces goes to the coolant, I think you'd have no problem running a water pump and alternator off of the heat alone. The only problem is keeping the engine running for the first 3 minutes or so until the motor warms up and can actually turn the alternator. I wouldn't doubt that a normal car battery will discharge in less than 3 minutes of running without an alternator.