You likely are not producing enough voltage with your turbine design. The color of an LED determines the minimum voltage needed for it to emit light. This has to do with the colors of light having different amounts of energy. A colored LED is not a white LED with a colored piece of plastic around it. It actually emits only light of a given color.
The voltage required for LEDs to light up are:
- Red LEDs require about 1.5 – 1.8 V
- Green LEDs require about 2.3 V
- Blue LEDs require about 2.9 – 3.1 V
Related:
Where can I get replacement LEDs to use with the KidWind SimpleGEN?
Where can I get the electronic components used in Vernier physics experiments?