By George Harvey
When I was young, a telephone had no dial on it. When you picked up the phone, you heard a female voice say, “Number, please.” There was no Caller ID, a long-distance call meant contacting a long-distance operator, and a call to Europe could cost $20, half a week’s pay for some people, for just the first three minutes.
In those days, designing a power plant included getting estimates of what the greatest demand would be, and building the plant to cover that and a little more. Since the generating plants had huge boilers, it took days to get them up and running after a shutdown. And so they ran all night at full power, when no one wanted power, just to be able to cover the peak demand of the following day, when factories operated and people went about their daytime lives.
Wholesale prices were mostly a simple matter of demand, because the supply was nearly constant. During the day, the spot price of power was high, because that was when power demand was high. During the night, the spot price went low, because demand was low.
Read more at geoharvey: The Virtual Power Plant on an All-Renewable Grid.