Energy Source	Net Energy Generation
Coal	1,554
Petroleum	158
Gas	267
Nuclear	529
Hydroelectric	265

Source: Electric Power Annual 1989, Energy Information Administration, Office of Coal, Nuclear, Electric, and Alternate Fuels, U.S. Department of Energy, Washington, D.C., January 1991, p. 14.

The table above shows how much energy was produced by each of the major sources in the United States.  The figures are in billions of kilowatt-hours.

Coal is not only the leading source of energy, but accounts for more than half of the country's energy supply.

One of the most interesting, and perhaps concerning, pieces of information that these statistics give us is that the vast majority of our energy comes from non-renewable sources.  At some point in the future, these sources of energy will inevitably give way, and new forms of energy will have to be found.