Reasons For Reduced Capacity Factor
There are several reasons why a plant would have a capacity factor lower than 100%. The first reason is that it was out of service or operating at reduced output for part of the time due to equipment failures or routine maintenance. This accounts for most of the unused capacity of base load power plants. Base load plants have the lowest costs per unit of electricity because they are designed for maximum efficiency and are operated continuously at high output. Geothermal plants, nuclear plants, coal plants and bioenergy plants that burn solid material are almost always operated as base load plants.
The second reason that a plant would have a capacity factor lower than 100% is that output is curtailed because the electricity is not needed or because the price of electricity is too low to make production economical. This accounts for most of the unused capacity of peaking power plants. Peaking plants may operate for only a few hours per year or up to several hours per day. Their electricity is relatively expensive. It is uneconomical, even wasteful, to make a peaking power plant as efficient as a base load plant because they do not operate enough to pay for the extra equipment cost, and perhaps not enough to offset the embodied energy of the additional components.
A third reason is a variation on the second: the operators of a hydroelectric dam may uprate its nameplate capacity by adding more generator units. Since the supply of fuel (i.e. water) remains unchanged, the uprated dam obtains a higher peak output in exchange for a lower capacity factor. Because hydro plants are highly dispatchable, they are able to act as load following power plants. Having a higher peak capacity allows a dam's operators to sell more of the annual output of electricity during the hours of highest electricity demand (and thus the highest spot price). In practical terms, uprating a dam allows it to balance a larger amount of intermittent energy sources on the grid such as wind farms and solar power plants, and to compensate for unscheduled shutdowns of baseload power plants, or brief surges in demand for electricity.
Read more about this topic: Capacity Factor
Famous quotes containing the words reasons for, reasons, reduced, capacity and/or factor:
“Write to the point: say immediately what you want to say most, even if it doesn’t “come first.” There are three reasons for doing this. First, you will then have said it, even if nothing else gets said. Second, your readers will then have read it, even if they read no more. Third, having said it, you are likely to have to say something more, because you will have to explain and justify what you chose to say.”
—Bill Stott (b. 1940)
“Whenever we approve, we can find a hundred good reasons to justify our approbation. Whenever we dislike, we can find a thousand to justify our dislike.”
—Samuel Richardson (1689–1761)
“The newspapers are the ruling power. Any other government is reduced to a few marines at Fort Independence. If a man neglects to read the Daily Times, government will go down on its knees to him, for this is the only treason these days.”
—Henry David Thoreau (1817–1862)
“That way of life against which my generation rebelled had given us grim courage, fortitude, self-discipline, a sense of individual responsibility, and a capacity for relentless hard work.”
—Rose Wilder Lane (1886–1968)
“Children of the middle years do not do their learning unaffected by attendant feelings of interest, boredom, success, failure, chagrin, joy, humiliation, pleasure, distress and delight. They are whole children responding in a total way, and what they feel is a constant factor that can be constructive or destructive in any learning situation.”
—Dorothy H. Cohen (20th century)