The power stations continue to run as normal, as they must do, to generate the electicity required before and after earth hour.
But never let the facts get in the way of that green, feel good, Bob Brown style logic.
And then we could get into the debate that it is a scientific fact that CO2 is not a major greenhouse gas in the first place.....but I'll leave that one, lest I wind up the usual suspects and they over-heat.