A conversation I joined on ChangeEverything.ca has been bugging me, because it reminded me of something I heard as a child, from an adult: you don’t have to worry that leaving lights on at night is wasteful, because the nocturnal hours are off-peak and the electricity is just, as he put it, “water over the dam”. (I guess he meant under the dam and through the generating station, but you get the idea: the electricity’s being generated whether we use it or not.)

It’s bothered me ever since, because it seems just a little too convenient. This week, I finally asked someone about it at BC Hydro… and guess what?

In off-peak hours, large-scale hydro dams actually do throttle back on generation. Water builds up in the reservoir, storing energy; in the morning, the intake opens and the water flows again, transferring energy to the turbines and then the generators.
In short, just because it’s an off-peak time of day doesn’t mean we get a karmic free pass on wasting electricity. It still increases the demand on the system.

So there. Turn off the lights before you go to bed, dammit.