This is my second electricity-related question tonight and I’m probably the only person in the world who has ever wondered this. “Kilowatt hour” is a unit of energy but it’s redundant. The unit for energy is the joule. The kilowatt measures power, which is energy divided by time, but a kilowatt hour is energy divided by time then multiplied by time so time drops out and energy is all that’s left. So, why not cut out the middleman and just bill electricity in joules instead of kilowatt hours?
