You may think there’s no more boring topic than electric utilities. Power plants. Transmission lines. Engineers with flat top haircuts and pocket protectors full of pens in their white short-sleeved shirts.
Well, let me tell you two words that might help make them more interesting: duck curve. If you haven’t heard this term yet, you’re not alone.
A primer on utility load curves
The graph below shows a typical daily load profile for an electric utility. This one’s for a day in New England in 2010, but the basic pattern is similar to what most electric utility load curves look like.
Demand for electricity is at its lowest during the night. When people wake up and start their day, demand rises (morning ramp). Then it stays up at a higher level through the day but rises to a peak after work ends and everyone returns home.
That’s what a typical day looks like in a lot of places. In addition, there are annual changes and utilities are often classified as either summer peaking or winter peaking. That’s just what you think: which season the utility hits its highest peak load for the year.
Utilities meet that demand in two ways. They have baseload plants and peaking plants. Baseload plants are mostly coal-fired here in the Southeast and mostly hydro in the Northwest. Peaking plants are often fueled by natural gas.
Now, what electric utility companies would like their load curve to look like is shown below.
If the demand were perfectly flat, a utility’s job would become trivial. (Of course, there’s all that messy stuff about storms and growth and plant outages, but let’s ignore that here.) Push the button and let…