SOURCES OF ENERGY

The extensive use of energy is a fundamental characteristic of the U.S. economy. The United States accounts for slightly less than 6 percent of the world's population but consumes approximately 33 percent of its energy. On a per capita basis, the U.S. is by a wide margin the world's largest consumer of energy. While these figures indicate the importance of energy, the complete role of energy in the U.S. economy is not adequately represented by quantitative measures, because energy use also contains an important qualitative dimension.

The immense energy requirement of the U.S. is met mainly by fuels: crude oil, natural gas, coal, and uranium. Some 95 percent of total energy supply is accounted for by coal, oil, and natural gas. Nuclear energy, while holding promise for the future, presently supplies a very small percentage of the total. It is traditional to distinguish among energy sources by referring to primary and secondary sources. Primary sources include coal, oil, natural gas, and uranium; electricity, the production of which requires the conversion of primary sources, is considered to be a secondary source of energy.

The technological ability to convert primary energy sources into electricity creates a unique interrelationship between electricity and primary sources of energy in end uses where electricity is consumed as an indirect source of energy. This type of relationship led the Energy Study Group to state:

To the extent that electricity can be substituted for other forms of energy in any use, substitution among all primary fuels is at once possible in that use.... Even when direct use of some fuels would