…The Incredible, Amazing Duck…
The Duck Curve was born in California, when the California Independent System Operator (CAISO) needed to explain how the addition of renewables affected the grid.
A quick explanation of the anatomy of the Duck Curve:
- The topmost line is the hour by hour electric load before the addition of renewables, where all of the load is supplied by baseload power plants.
- The orange body depicts the addition of renewables on the grid year by year, through 2020, where the orange area is supplied by renewables.
- The heavy line at the bottom of the curve, and the lighter lines inside the orange body for intervening years, depict the load supplied by baseline power generation after the addition of renewables.
Baseload power is typically supplied by natural gas combined cycle (NGCC) power plants, or nuclear, hydro, or coal, or a combination of them depending on which area of the country is being discussed.
Here is what the Duck is telling us.
- As more and more renewables are added to the grid the amount of electricity supplied during the daylight hours is increasingly from renewables, primarily from solar in this depiction.
- Baseload power must be quickly reduced as the sun rises to allow renewables to supply the grid.
- When the sun sets, these same baseload power plants must suddenly ramp up to meet the demand in the evening. The sudden ramping up of the power plants damages the power plants, except hydro, and various components of the grid from thermal expansions and contractions.
- Renewables are intermittent, the sun may go behind a cloud or the wind may stop blowing, so the baseload power plants must be cycled up and down to meet the variations in load. Power plants are less efficient when they are cycled in this manner which can cause an increase in air pollution, such as NOx.
It’s obvious the sun won’t shine when it rains or snows, but it’s also true wind can’t generate electricity when the wind is less than 6 mph, such as on hot summer windless afternoons. And wind turbines must be shut down when the wind blows over 55 mph, or when the temperatures go below minus 20 degree F in the winter.
- From after the sun sets until it rises in the morning, the preponderance of the electricity must come from baseload power plants, so they cannot be dismantled and eliminated. Renewables can’t eliminate baseload power plants unless electricity can be stored, which raises a large number of additional issues.
- The next picture of the Duck Curve implies what happens when renewables supply an increasing amount of electricity. All of the above problems are exacerbated, and it eventually becomes clear that utilities that own baseload power plants may find it difficult to survive without government intervention.
Storage would solve many of these problems, but even if it is technically possible to store all the electricity needed during 24 hours of the day, the amount of storage required to ensure the availability of electricity for several days when the sun doesn’t shine and wind can’t generate electricity, will cost trillions of dollars, about equal to our national debt. Storage is discussed in detail in the book Energy: The Source of Prosperity and at, Four Minutes for $150 million
The Duck tells us a great deal about renewables, and is an excellent reference whenever renewables are discussed.
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