Overheard: Windmills are Like Coupons

Whenever we pass windmill turbines, we explain to the girls that they are generating electricity for buildings when they are turned by the wind. Ted even dreams of having one of his own someday!

Ted: Girls, look at the windmills!
H: But they're not turning, there's no wind.
G: Does that mean there's no electricity in the buildings so they can't turn on the lights?
Ted: No, when the windmills turn, it's like "extra". (Ted went on to try to explain a couple different ways that they don't generate instant electricity, but give a "credit". They weren't getting it.)
Jessica: Girls, windmills are like coupons. When they're turning, the people in the buildings save money on electricity.
H&G: Oh, that makes sense!

Everything comes back to coupons with me! :-)