As of January 2021, the United States had almost 200 gigawatts (GW) of electric generating capacity that could functionally switch fuels, or about 18% of the total 1,116 GW of utility-scale electric generating capacity. About two-thirds, or 745 GW, of all utility-scale generating capacity involved technologies that could potentially use multiple energy sources, such as combustion turbines and steam turbines, as opposed to 371 GW of capacity that are single-source technologies such as wind turbines, hydroelectric dams, and nuclear reactors.