Quote:
Originally Posted by mcgeedo
I was watching Discovery Channel today, idly taking in a program whose name I don't remember, that was talking about "environmental tech." The narrator casually threw out a line: "If half of the households in the United States switched just one incandescent buld to a compact fluorescent buld, it would save the equivalent of the emissions of 800,000 cars for a year."
It really ticks me off when those who want to save us from ourselves make up crap like this and try to pass it off as fact. They apparently feel that no one will fact check and call them on it, and even if someone does, the debunking won't get the same exposure. Just quote numbers, repeat it often enough and pretty soon the sheep will believe it.
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Let's check the numbers, shall we?
US households = 105,480,101
Power savings of a Bulb = say 80 W
Be generous, and presume the Bulb is on 50% of the time.
Presume the bulb has a 10 year life expectancy
80 W * 10 years / 2 = 1.3 * 10^10 J, or 3,506 kWh
* 50 million = 1.753 * 10^11 kWh
Nuclear generates less than 17 g/kWh of CO2. So this is 2,980,100,000,000 g of CO2, or 3 million tonnes of CO2.
I'll say 200 lbs of CO2 per million BTU for coal (quick google search). So that's 5.42681444 × 10^10 kg, or ~5 * 10^7 tonnes, of CO2, or 50 million tonnes.
A car (I picked a 2 L mazda) generates about 198 g/km.
Say the car in question drives 20,000 km/year.
800,000 cars at 20,000 km/year at 200 g/km is 3,200,000,000,000 g of carbon.
Or 3.2 million tonnes of CO2.
In short, doing a quick check of the numbers, it seems to work out using somewhat reasonable assumptions.
Admittedly, the bulb is more likely to be burning CH4 on the margin and not coal. And I did have the lightbulb be on for 5 years solid before burning out.
The car probably would be driven further than that, and I ended up with 50 million tonnes of CO2 vs 3 million tonnes of CO2 for the cars.
Any mistakes in my math?
What math did you do to confirm that the story was wrong? I'd like to see it, maybe I'd find a mistake in my math!