Capacity factors are calculated by dividing the actual electricity produced by a generating unit by the maximum possible electricity that could have been produced if the generator operated at continuous full power. A capacity factor of 100 percent, for example, means the unit is operating all of the time and produces baseload power.
The new EIA’ Electric Power Monthly contains capacity factor data for 16 power plant technology types. In focus are time-adjusted total capacity values by technology type considering fuel costs and plant retirements.
Usage factors of energy storage
Gross generation data for battery and pumped storage applications are also included in the EIA’s detailed electric power survey. This includes capacity factor data based on gross generation for pumped storage and batteries.
Usage factors for storage generators differ from capacity factors because usage factors are based on gross generation rather than net generation, analyst pointed out. Energy storage technologies tend to consume more energy than they store and, therefore, always have negative net generation.
Storing excess electricity at times of low demand and often relatively inexpensive prices, can create value when that stored electricity is resold in high-demand periods at high, peak-load power prices.
Pumped storage, based on pumping water in storage reservoirs for hydro-electric generation, is still the largest source of electricity storage in the United States. Usage factors for pumped storage tends to have a large peak in summer, a smaller peak in winter, and the lowest use in spring and fall. By comparison, the usage factors for batteries are relatively low and less seasonal.