How are they Green?

LED bulbs light only by the movement of electrons. They have no filament that will burn out; and unlike CFLs, they contain no mercury or other toxic substances. LEDs can last some 60 times longer than incandescents and 10 times longer than CFLs. And unlike incandescents, which generate a lot of waste heat, LEDs don’t get hot and use a much higher percentage of electricity for directly generating light.