Circuit for Battery powered LED turned on by .15 volts from small wind generator.
Connect the generator to Emitter of some NPN transistor (small signal is fine).
Connect the collector to 100 ohm resistor, other lead of resistor to LED's cathode (bar of the bar+arrow symbol), LED's anode to +3 volts.

Now the key: use 2 resistors to bias the NPN transistor's base to 0.5 volts; figure 100microAmp drain on the battery at all times, unless you include a switch. We want 0.5 volts across the bottom resistor, 2.5 volts across the top resistor. A good way to view resistors, to design without a chululator, is express the current as Ohms/Volt; our 100uA is 10,000 ohms per volt. Thus we need 5Kohm from base to GND/RTN/-Battery, and 25,000 from base to VDD/+Battery.
If you don't have exactly those, use 4.7Kohm and 24Kohm.