Would it ever work to stick small turbines in each wheel and then use the already-existing rotation of the wheel to turn the turbine, thus generating a small amount of electricity for running devices inside the car? Ultimately, the idea is just to take the main engine to turn the wheels and then use that turning motion to generate electricity inside the wheel. Therefore, this would only be of interest if the amount of energy generated by the wheel generators is larger than the extra amount of energy the main engine must use to move the car with the extra weight of the turbines.
However, I think this idea is better than the repeated wind turbine ideas in the following way: Since the turbines are embedded inside pre-existing wheels, the wheel generators would only be using kinetic energy that was already necessary, NOT relying on extra drag to turn the turbine. The only energy directly going to these wheel generators is whatever's needed to carry their weight. I realize the charge would therefore be relatively small compared to the amount needed by the engine, but perhaps it would still be of some use. I think this is all different from the hubmotors discussed here (http://www.whynot.net/ideas/2769) and the Tesla disc generator mentioned here (http://www.whynot.net/ideas/4666). It's also, I think, different than capturing energy from breaks which is already implemented in existing vehicles.
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your idea is no different from the other 'turbine on car' ideas, just because you moved them does not change the physical principals. as you said, it only works if you get more energy out than what the engine has to expend because of them, more energy out than in is the definition of an impossible machine, being more than 100% efficient.
pacatrue, think of it like this--it you shut the engine off would this keep producing power? No. Then the power it's making is from the engine.
Yes, it would make power during the coast-down after the engine is off, but that power equates to the brake-regenerator you said you weren't talking about. Even that power came from the engine originally.
Sure, I'm under no illusion that this will create new energy. I'm just wondering if it can recapture some of the engine's energy that would otherwise disappear. (I may be under many other illusions, which is why I posted it here.) Let's declare a few variables. Let N be the normal amount of energy the main engine must expend to turn the wheels, moving the car. Let M be the amount of energy it takes to move the wheels with the turbines loaded in the wheels. Since they are encased, that will largely be based off of their weight. N-T, then, is the extra energy required just to push the turbines around, which is M-N.
I fully understand that the amount of energy created by the wheel turbines will not exceed that N-T value. Conservation of energy and all. No problem. (I realize I suggested this was possible in my original post.) But I'm not sure that N-T is the energy we're after. It's really that original N value.
My understanding of the wind turbines is that they are only operated by creating extra drag which pushes the blades of the turbine. The parallel in this would be driving the wheel turbines off of the N-T energy. But that's not what I am hoping to do. The car is already turning the wheels using its N energy. If one portion of the inside of that spinning wheel is magnetic, with the electric coil inside that, wouldn't it recapture some of that N?
My guess is that the main flaw in my reasoning is believing that there's some wasted amount of N, which the wheel turbines could extract. But I don't understand cars and energy enough to know if there really is such wasted energy. Perhaps they would simply be sucking energy away from the original purpose of turning the wheels, and then the whole thing falls apart.
Pacatrue, your guess at the end is right. Any energy wasted at the wheel will be from friction, which is lost as heat. Your device would extract kinetic energy, not heat. Any device that extracts kinetic energy from the wheel will decelerate the wheel, forcing the engine to work harder to keep it turning. All of the kinetic energy removed from the wheel will have to be supplied by the engine. There is no net gain at all.
BTW, a turbine is a device that uses a moving fluid (gas or liquid) to turn a shaft by pushing on blades of some sort. A device using magnets would not be called a turbine, though I'm not sure what it should be call.
This is probably been suggested before. What aboout a small turbine fitted at the mouth of exhaust? Would the exhaust gas provide enough free energy to power the the cigarette lighter and door lamp in the car and still be profitable, energy wise, to warrant such a set up?
"BTW, a turbine is a device that uses a moving fluid (gas or liquid) to turn a shaft by pushing on blades of some sort. A device using magnets would not be called a turbine, though I'm not sure what it should be call."
Would probably be a DC motor as they are generators when turned. This idea is common in RC vehicles.