Which is not a source of electrical energy in the United States

Every practical source of energy that you can imagine, as well as a few impractical ones, are used somewhere in the USA.

From whale oil in Alaska, to nuclear energy, to coal, petroleum, natural gas, solar energy, wind energy, and biomass.

Oh! Geothermal energy and tidal energy aren't too popular, but I'll bet if you looked, you'd find these used too, SOMEwhere in the 50 states.