How much electricity does a power plant generate?
The amount of electricity a power plant generates depends on its electricity generation capacity and on the amount of time the generators at a power plant operate at a specific capacity. For example, if a power plant with a single generator has an electricity generation capacity of 100 megawatts (MW) and operates at that capacity continuously for 24 hours, it will generate 2,400 megawatthours (MWh) of electricity. If the power plant operates at that capacity continuously for 365 days, it will generate 876,000 MWh.
Most power plants do not operate at full capacity all the time, and for many, their electricity generation capacity is different in summer than in winter months because of seasonal variations in the temperature of generator cooling fluid (water or ambient air).
There are three categories of electricity generating capacity:
A measure of electricity generation capacity relative to electricity generation is the capacity factor. We publish the average monthly and annual capacity factors for utility-scale electric power generators (generators with a nameplate generation capacity of at least 1 MW) by those that primarily use fossil fuels and those that do not primarily use fossil fuels in Tables 6.07A and 6.07B, respectively, of the Electric Power Monthly. Details on how we calculate capacity factors are included on page 21 of the Electric Power Monthly Technical notes.
Nuclear plants usually operate at or near their electric generating capacity throughout the year to provide base-load electricity generation. So, nuclear power reactors have the highest average monthly and annual capacity factors. In the United States, nuclear power plants reduce generation to refuel every 18 to 24 months, mostly in fall and spring, when electricity demand is lower.
Capacity factors at coal-fired power plants have declined largely because of increased use of natural-gas and renewable energy as sources for electricity generation. Petroleum-fired power plants have the lowest average monthly and annual capacity factors because they are generally only operated to supply electricity during periods of very high electricity demand. The exceptions are Hawaii, where petroleum fuels are major electricity generation sources, and remote villages in Alaska supplied by diesel-fueled electricity generators. Geothermal and biomass-fired power plants have the highest capacity factors among renewable power plants because their energy sources are relatively constant. Hydroelectric generation is affected by precipitation levels that vary seasonally. Wind and solar power plant electricity generation and capacity factors are determined by availability of wind and solar energy both daily and seasonally.
Learn more:
What is the difference between electricity generation capacity and electricity generation?
What is the efficiency of different types of power plants?
Does EIA have data on each power plant in the United States?
Capacity factors for utility scale generators primarily using fossil fuels
Capacity factors for utility scale generators not primarily using fossil fuels
U.S. nuclear generation and generating capacity (historical monthly capacity and generation by state and reactor)
Energy Explained: Electricity generation, capacity, and sales in the United States
Monthly Energy Review, Nuclear energy (historical monthly and annual data on the total number of U.S nuclear reactors, electricity generation capacity, electricity generation, and capacity factors)
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