Zoran,
The energy you are trying to capture with the wind turbine IS the movement of the air, commonly known as wind. It doesn't matter what kind of turbine you are using, the ABSOLUTE MAXIMUM energy you could pull out of the wind is 59.2% of the energy moving through your swept area. If you try to extract any more it will just go around your windmill instead of through it. That is the limitations of ANY windmill.
Now lets talk about your alternator. It does not matter where the magnets and coils are, they can be a relatively small alternator on the shaft or magnets on the tips of the blades going past coils, they have the EXACT same function, and all alternators are less than 100% efficient, so there are more losses. If you match your alternator as perfectly as you can to be most efficient at low speed and capture as much of the tiny bit of energy that exists in low wind speeds. (A fraction of near nothing is even nearer nothing.) Your alternator will also be very inefficient at higher speeds and will need to be limited so it doesn't burn up, sacrificing energy at higher wind speeds. Which would have actually been useful energy.
I don't think I can explain it any simpler, you have been given lots of explanations so far, Sorry I can't help you any further.