In 2019, 9 of the 10 highest-generating U.S. power plants were nuclear plants

According to U.S. Energy Information Administration (EIA) data on power plant operations, 9 of the 10 U.S. power plants that generated the most electricity in 2019 were nuclear plants. These 10 plants generated a combined 230 million megawatthours (MWh) of electricity in 2019, accounting for 5.6% of all electricity generation in the United States. The makeup of power plants that generate the most electricity has shifted in the past 10 years from a mix of nuclear and coal plants to almost all nuclear in 2019.

In 2010, the top 10 highest-generating power plants in the United States were a mix of nuclear and coal-fired generators. In 2010, coal’s share of U.S. electricity generation was 45%, compared with 23% in 2019. Decreased cost-competitiveness relative to other power resources, especially natural gas, has made coal less economical for electricity generation. Coal plants are also run at lower levels because of tighter air emission standards, which is the primary reason coal plants fell from the top 10.

The Palo Verde, Browns Ferry, and Oconee nuclear power plants have consistently been among the 10 largest generators of electricity in the United States because they are the only nuclear plants with three reactor units, which gives them more generating capacity. A plant’s refueling and maintenance schedules may also affect annual electric power generation capacity. For example, Comanche Peak was one of the top 10 highest-generating power plants in 2010 but was not one in 2019 because scheduled refueling and maintenance reduced plant availability in 2019.

Electric power plants that have relatively large electricity generating capacities generally also operate at high capacity factors, or utilization rates. The capacity (the maximum amount of electricity a power plant can produce) of the top 10 highest-generating power plants in 2019 ranged from 2,300 megawatts (MW) (Byron) to 3,937 MW (Palo Verde). Although these plants have a lower nameplate capacity than the Grand Coulee hydroelectric facility (6,809 MW of capacity) in Washington, they generate more electric power each year. Grand Coulee operated at a lower utilization rate and generated 16.6 million MWh of electricity in 2019.

Nuclear power plants have the highest capacity factor of any energy source in the United States, at 94% fleet-wide in 2019, because nuclear plants generally operate around-the-clock until they are taken offline for maintenance or refueling. Capacity factors for the nine nuclear plants in the top 10 range from 89% (Browns Ferry) to 99% (Byron and Peach Bottom). Natural gas combined-cycle units have the second-highest capacity factor in the United States, at 57% fleet-wide in 2019. The natural gas plant that was among the top 10 highest-generating power plants in 2019, West County Energy Center, operated at a capacity factor of 65%, slightly higher than the fleet-wide capacity factor.

Almost all of the U.S. power plants that generated the most electricity in 2019 were in the eastern half of the country, and they tended to be close to areas with high electricity demand such as major cities or industrial production centers