Electricity, the #1 Secondary Source

Electricity can’t be pumped out of the ground like oil or captured from moving air like wind energy. So it is called a secondary source of energy, meaning that it is produced by the use of primary energy sources such as coal, natural gas, or nuclear reactions. Electricity plays such an essential role in contemporary America that its supply and demand are often examined separately from the primary sources used to produce it.


Experts predict a 35% increase in demand for electricity by 2030. In practical terms, that means an equivalent increase in demand for coal and gas, at least for the next decade: Electricity generating plants now consume two-fifths of U.S. energy from all sources, including 90% of America’s coal and nearly 30% of its natural gas.


There is no immediate way to alter that situation. In the near term, renewable sources such as solar, wind, and geothermal are unlikely to substantially change the mix of our energy supply. (And integrating the energy from many of these renewable energy sources would likely require substantial expansion of the electric transmission system.) While nuclear generation is a zero-atmospheric-emissions alternative that already produces one-fifth of America’s electricity, efforts to increase that capacity face two large, though not insurmountable, hurdles: high capital investment costs and resistance from citizens groups that oppose the use and storage of radioactive material.


Getting electric power to consumers may be as much of a problem as generating it. Generating stations usually are built away from load centers because sites are easier to find and fewer people are disturbed by the accompanying noise, emissions, and activity. This power must be delivered by a high-voltage transmission system that has become increasingly stressed in recent years as growing demand has outstripped capacity. Widespread blackouts are possible, as evidenced by the August 2003 disruption to 50 million customers from Ohio to New York and Canada. New transmission lines are difficult to build because of uncertain cost recovery and public opposition. Building small plants near customers, known as distributed generation, may become more important in order to meet demand and maintain reliability.

Energy sources used to generate electricity in the United States in 2006.*

Energy sources used to generate electricity in the United States in 2006.*

* Percentages do not sum to 100% due to independent rounding.



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