The energy to power the nation’s economy—to provide fuels for its vehicles and furnaces and electricity for its machinery and appliances—is derived primarily from petroleum, natural gas, and coal. Measured in terms of heat-producing capacity (British thermal units, or Btu), petroleum provides 41 percent of the total energy consumed in the United States, according to the United States Energy Information Administration (EIA). It supplies nearly all of the energy used to power the nation’s transportation system and heats millions of houses and factories.
In 2004, the latest year for which figures are available, natural gas was the source of 23 percent of the energy consumed.
Many industrial plants use natural gas for heat and power, and several million households burn it for heating and cooking. Coal provided 22 percent of the energy consumed. Its major uses are in the generation of electricity, which uses more than three-fourths of all the coal consumed, and in the manufacture of steel. Waterpower generates 6 percent of the nation’s energy, and nuclear power supplies 8 percent. Both are employed mainly to produce electricity for residential and industrial use. Nuclear energy has been viewed as an important alternative to expensive petroleum and natural gas, but its development has proceeded somewhat more slowly than originally anticipated. People are reluctant to live near nuclear plants for fear of a radiation-releasing accident.
Another obstacle to the expansion of nuclear power use is that it is very expensive to dispose of radioactive material used to power the plants. These nuclear fuel materials remain radioactive for thousands of years and pose health risks if they are not properly contained.
Some 33 percent of the energy consumed in the United States is used in the generation of electricity. In 2007 the nation’s generating plants had a total installed capacity of 1,087,791 megawatts and produced 4.06 trillion kilowatt-hours of electricity. Coal is the most common fuel used by electric power plants, and 57 percent of the nation’s yearly electricity is generated in coal-fired plants. The states producing the most coal-generated electricity are Ohio, Texas, Indiana, Pennsylvania, Illinois, West Virginia, Kentucky, and Georgia. Natural gas accounts for 9 percent of the electricity produced, and refined petroleum for 2 percent. The states producing the most electricity from natural gas are Texas and California.
Refined petroleum is especially important in Florida, New York, and Massachusetts. The leading producers of hydroelectricity are Washington, Oregon, New York, and California. Illinois, Pennsylvania, South Carolina, and California have the largest nuclear power industries. Petroleum is a key resource for an American lifestyle based on extensive use of private automobiles and trucks for commerce and businesses. Since 1947, when the United States became a net importer of oil, annual domestic production has not been enough to meet the demands of the highly mobile American society.
In 1970 domestic crude-oil production reached a record high of 3.5 billion barrels, but this had to be supplemented by imports amounting to 12 percent of the nation’s overall crude oil supply. Most Americans were unaware of the dependence of the country on foreign petroleum until an oil embargo imposed by some Middle Eastern nations in 1973 and 1974 led to government price ceilings for gasoline and other energy products, which in turn led to shortages.
In 1973 the nation imported about one-fourth of its total supply of crude oil. Imports continued to rise until 1977, when about half of the crude and refined oil supply was imported. Imports then declined for a time, largely because energy-conservation measures were introduced and because other domestic energy sources such as coal were used increasingly. As of 2004, however, 58 percent of the petroleum products and crude oil needs of the United States were met by net imports. The United States consumes 25 percent of the world’s energy, far more than any other country, despite having less than 5 percent of the world’s population.
The United States also produces a disproportionate share of the world’s total output of goods and services, which is the main reason the nation consumes so much energy. In addition, the U.S. population is spread over a larger area than are the populations in many other industrialized nations, such as Japan and the countries of Western Europe. This lower population density in the United States results in a greater consumption of energy for transportation, as truck, trains, and planes are needed to move goods and people to the far-flung American citizenry. As a result of the nation’s high energy consumption, the United States accounts for nearly 20 percent of the global emissions of greenhouse gases. These gases—carbon dioxide, methane, and oxides of nitrogen—result from the burning of fossil fuels, and they can have a harmful effect on the environment. See Greenhouse Effect. "USA" © Emmanuel BUCHOT, Encarta, Wikipedia
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