Frequently Asked Questions

What is a capacity factor?

Capacity factor is a measure of how often an electric generator runs for a specific period of time. It compares how much electricity a generator actually produces with the maximum it could produce at continuous full power operation during the same period.

For example, if a 1 MW generator produced 5,000 MWh over a year, its capacity factor would be 0.57 because 5,000 MWh equals 57% of the amount of electricity the generator could have produced if it operated the entire year (8,760 hours) at full capacity and produced 8,760 MWh of electricity.

Generators with relatively low fuel costs are usually operated to supply baseload power, and typically have average annual capacity factors of 0.70 or more. Generators with lower capacity factors may indicate they are in operation during peak demand periods and/or have high fuel costs, or their operation depends on the availability of the energy source, such as hydro, solar, and wind energy.

Learn More:

Table 5.2. Average Capacity Factors by Energy Source, 1998 through 2009 (page 48) of the Electric Power Annual 2009.   Note that this is the most recent data available as EIA has discontinued publishing this data.

Last updated: May 13, 2013


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