David Roberts, Vox
For most of the 100-plus years that the electricity grid has been around, grid managers had control over the supply of power but not the demand for it.
Like the weather, or the tides, electricity consumption could be reasonably well predicted, but it couldn’t be controlled. It was something that just happened, to which grid operators responded by adjusting supply, turning power plants on or off, up or down.
The problem with having no control over demand, though, is that you end up overbuilding supply. You have to build enough power plants to satisfy the highest possible peak in demand (and a reserve on top of that, for extra reliability).
The thing is, peaks in demand are by definition exceptions. Most of the time, lots and lots of power plants, especially the “peaker” plants built purely to satisfy these brief windows of high consumption, just sit around, idle. Overbuilding has been the rule in the power system, at great cost in both money and efficiency.
In recent years, that dynamic has been changing, on both ends.
In supply, the story is familiar: As renewables grow, power is becoming less controllable (less “dispatchable” in the lingo). Wind and solar energy can’t be turned on and off at will — they come and go with the weather and time of day, so they must be accommodated, as demand once was.
But the less-familiar story is that demand is also changing, becoming more dispatchable.