Hi Jennifer,
I suppose you’ve heard about Sydney’s “Earth Hour”.
I’m not sure whether to be amused, or saddened, by TV footage showing people turning off their lights, and using candles instead. It seems to indicate a total lack of understanding.
Leaving aside whether CO2 emissions are really a problem, if these people thought they were reducing CO2 emissions by their actions, then I rather think they were deluding themselves. Earth Hour was held during a time of peak electrical load, so any electricity generation displaced would be peak load, probably running on natural gas. Such generation produces about 500 grams of CO2 for every kilowatt-hour.
So turning a 100 watt light bulb off for an hour saves 50 grams of CO2, or 13 grams of carbon. A candle is mostly carbon by weight, and candle wax is only moderately less dense than water at room temperature. This means that burning just 5 cm of a typical 2 cm diameter candle will produce more CO2 than running the 100 watt light bulb for an hour. If the light that was turned off is fluorescent, then even less candle can be burned if there’s to be a net reduction in CO2.
By the way, the Sydney Morning Herald published these pictures to show the effect of Earth Hour
In the ‘after’ picture, the lights that are still on are dimmer than they were in the ‘before’ picture, which rather implies that the ‘after’ picture is artificially darkened. That really is dishonest reporting.
Sylvia.
Jennifer Marohasy BSc PhD has worked in industry and government. She is currently researching a novel technique for long-range weather forecasting funded by the B. Macfie Family Foundation.
