The one I built sunday needs more wind then what we've had so far. I can blow on it to get it spinning a little, air compressor makes it go really fast. But I need to see it spin outdoors with natural wind.
The savorius rotor produces more torque then speed, consider gears or pulleys to get more speed. It'll spin regardless of wind direction, and doesn't need to point itself in any direction, compared to most.
This was my first, so might be a failure (hate it when nature doesn't cooperate). I made it small for a yard decoration, flash some LEDs.