Nuclear power remains the largest single source of carbon-free electricity in the United States, according to Energy Information Administration data. The fleet generates more than 782 billion kilowatt-hours annually, output that exceeds any other zero-carbon source on the U.S. grid.
The scale reflects both the number of reactors and their steady operation. With 94 licensed reactors supplying almost 20 percent of national electricity, nuclear contributes a consistent block of generation that does not vary with weather or daylight. The United States operates more nuclear generating capacity than any other nation, a position built over decades of plant construction and sustained through license renewals.
The generation figures carry weight in current grid planning. As utilities forecast sharp increases in electricity demand from data centers and electrification, they are counting on nuclear's around-the-clock output to provide a firm foundation beneath more variable sources. Recent plant restarts and the extension of existing licenses aim to preserve that generation base rather than let it erode as older units retire.
The EIA monthly generation data also captures the effect of the newest additions. Georgia's Plant Vogtle Units 3 and 4, which reached commercial operation in 2023 and 2024, added roughly 2,200 megawatts of new nuclear capacity, the first major increase to the national total in years and a measurable contribution to the carbon-free generation the data tracks.
Source: U.S. Energy Information Administration -- https://www.eia.gov/totalenergy/data/monthly/pdf/sec8_n.pdf