I have often threatened that I may just go postal at some point when I hear someone using the word "green," not in reference to an actual color.
Yesterday, at the auto parts store where I work part-time, we got our weekly stock order. In the order were some new parts, including Sylvania's "Green" Eco-Friendly Headlight bulbs. "W" as in What, "T" as in The, "F" as Heck?
Eco Friendly headlight bulbs? Really? I don't have the package in front of me, but the packaging makes some claims like reduced CO2 emissions, and reduced fuel consumption and money savings.
The only thing I noticed is that the low beam side was 48 watts, rather then the normal 55 watts. And they're $25 for a pair, instead of $10 each. Great. How is that going to save the planet?
Generally (but not always), the lower the wattage, the less bright the light output. So we may assume lower light output, though this may not be true, because Sylvania's own Silverstar and Silverstar Ultra produce a brighter (whiter) light with the same 55 watts.
After the engine is running, the electrical requirements of the vehicle are supplied by the alternator, which is driven by a belt, driven by the engine. Yes, it take energy to turn the alternator. Most modern day alternators can supply upwards of 140 amps. Watts are calculated by multiplying amps by volts, so assuming 14 volts, and 140 amps, you get a total of 1960 watts from the alternator.
Taking the same 14 volts, and subtracting the 48 watts from the new "green" bulb from the 55 watts from the "non-green" bulb, you get 196 watts of savings (for the pair). Approximately 10% of the max output of the alternator.
I'm sure there is a way to calculate how much fuel is consumed by generating X amount of wattage, but if your vehicle gets 25 MPG with your headlights on, the A/C at full blast, and the stereo cranking out your favorite tunes, while the kids are watching Spongebob in the back seat, how much fuel, and therefore CO2 emissions, are you going to save by reducing the headlight wattage consumption by 10% of total alternator output?
BTW, I do not buy into the idea that CO2 is a pollutant, unless it is exhaled from a politician spewing socialist propaganda.