|MadSci Network: Engineering|
I like the question very much. Fuel from water is a wonderful idea - imagine the renewable and sustainable resource we would be sitting on! I remember my earliest experiments in creating hydrogen by dropping iron filings into a mixture of water and Bicarbonate of Soda. I watched the little bubbles appear and daydreamed that I could run cars and generators on it. I imagined a huge tank of bubbling iron filings and water under the bonnet fuelling the car of the future! I digress.
There is no reason whatsoever why a car could not be fuelled by the results of electrolysis in water but there are certain practicalities to bear in mind. The calorific value of water is much less than that of any conventional fossil fuel, and therefore the amount of energy that could be transformed from, say 100kg of water may not produce enough motive force to move the apparatus, vehicle, and passengers at any useful rate. No problem if you generate the fuel seperately. The drawback then is, that you have the need to refuel somewhere other than a hosepipe, which was one beauty of your original idea.
I like the idea if dynamo brakes, but you must remember what happens in a dynamo when you suddenly change the operating state. It is unlikely that you would be able to achieve the same performace as conventional braking on a safe, repeatable, and cheaply replaceable basis.
There is nothing wrong with your theory, just the practicality of it. Sadly, the world will not buy things on the grounds of their ecological savings if they won't perform like a BMW. However, none of my comments would have distracted Thomas Edison, and I would rather aspire to him than to the market forces. Your idea works in principle, the practicalities are not problems, but challenges. Make me proud!
Try the links in the MadSci Library for more information on Engineering.