In 2019, 9 of the top 10 U.S. generating plants were nuclear plants, according to 2019 preliminary data from the U.S. Energy Information Administration’s (EIA) Form EIA-923. The top 10 plants accounted for approximately 230 million megawatthours (MWh), or 5.6%, of total 2019 U.S. net generation. The two leading plants, Palo Verde (31.9 million MWh) in Arizona and Browns Ferry (29.5 million MWh) in Alabama, each generated close to 30 million MWh. An additional cluster of nuclear plants—Peach Bottom (22.3 million MWh), South Texas Project (22 million MWh), Oconee (21.9 million MWh), Susquehanna (20.9 million MWh), Braidwood (20.3 million MWh), Byron (20.1 million MWh), and Vogtle (19.7 million MWh)—generated about 20 million MWh each. The one non-nuclear plant in the top 10 was the West County Energy Center, fueled primarily by natural gas, in Florida that generated 21.5 million MWh in 2019. Coal plants that were prominently on this list 5 to 10 years ago are absent because coal plants now tend to run at lower levels because of increased competition from natural gas and renewable energy plants.
Geographically, these large generating plants tend to be in the eastern half of the United States and close to large load centers. Susquehanna and Peach Bottom in eastern Pennsylvania are near the large load centers in the eastern portion of the PJM Interconnection. Byron and Braidwood in Illinois, in the western portion of PJM, provide power to the strong loads of northern Illinois. Oconee (South Carolina), Vogtle (Georgia), and Browns Ferry (Alabama) help serve the power needs of the upper South East. Meanwhile, the West Coast Energy Center provides power to the load centers of South Florida, the South Texas Project provides power to the Texas Gulf Coast, and Palo Verde provides power to Phoenix and other parts of the South West.
Large operating capacities and high capacity factors are common characteristics of these high net generation plants. Net summer operating capacity of these plants range from 3,937 megawatts (MW) for Palo Verde to 2,300 MW for Byron. Palo Verde, along with Browns Ferry (3,774 MW) and the West County Energy Center (3,756 MW) are, after the Grand Coulee dam in Washington, the second-largest through fourth-largest capacity plants in the nation. In addition, these plants (as baseload plants) operate at high capacity factors. Capacity factors for the nine nuclear plants in the group range from approximately 89% for Browns Ferry to about 99% for Byron and Peach Bottom. The high capacity factors for nuclear plants are expected because nuclear plants are not designed for load following and generally operate continuously around-the-clock until they are taken offline for maintenance or refueling. The one natural gas plant in the group, West County Energy Center, operated at a lower capacity factor (65%) relative to the nuclear plants. This capacity factor is also consistent with large, cost-competitive natural gas plants that tend to follow load, cycling up and down over the daily load curve, and that tend to operate with annual capacity factors ranging from 60% to 70%.
For several years, nuclear plants have been among the top 10 net generation plants on a consistent basis. In 2015, 9 of the 10 top net generation plants were also nuclear or primarily nuclear plants. The 2015 list includes seven of the same plants in the 2019 group of top net generation plants. Plants on the 2015 list of top generating plants that were not in the top 10 in 2019 include Comanche Peak in Texas, McGuire in North Carolina, and Turkey Point in Florida. Turkey Point is unique in that it has both significant nuclear (1,658 MW) and natural gas (1,253 MW) capacity, and this characteristic is reflected in its 2015 generation mix between nuclear-based and natural gas-based generation. The lack of variation between the 2019 and 2015 lists illustrates how the largest new plants going into operation now are natural gas combined-cycle plants between 1,000 MW and 1,700 MW that are not capable of annual generation levels of 20 million MWh because of capacity constraints. The largest new plant that came online in 2019 was the Okeechobee Clean Energy Center in Florida, a 1,723 MW natural gas combined-cycle facility.
In 2010, however, both nuclear and coal were predominately in the 2010 top 10 net generation plants. The six nuclear plants (Palo Verde, Browns Ferry, South Texas, Oconee, Comanche Peak, and Byron) were also among the top 10 generators in both or either 2019 and 2015. Palo Verde, Browns Ferry, and Oconee are consistently in the top 10 because they are the only nuclear plants with three units. The two-unit nuclear plants shift around depending on refueling/maintenance schedules. For example, Comanche Peak is in the top 10 in both 2015 and 2010 but not 2019 because scheduled refueling/maintenance reduced plant availability to 91% of capacity in 2019. The four coal plants included in the 2010 top 10 net generation plants—Bowen (23.2 million MWh), Scherer (23.1 million MWh), James H Miller (20.6 million MWh) and Gibson (20.2 million MWh)—show coal’s strong position in the 2010 generation market. In 2010, coal’s market share of U.S. net generation was 45%. Preliminary data for 2019 indicate that coal’s share of 2019 U.S. net generation was 23%.