摘要：Energy is vastly produced and consumed in the United States. Between 1949 and 2009, energy production in the United States increased nearly 130 percent (from 31.722 quadrillion Btus to 72.970 Btus), while U.S. energy consumption increased by approximately 196 percent (from 31.982 Btus to 94.578 Btus) (EIA 2010a). The vast majority of the roughly 94.6 quadrillion Btus of energy consumed in the United States in 2009 (approximately 83 percent) came from the combustion of fossil hydrocarbon fuels. In 2009, petroleum provided roughly 37 percent of the nation’s energy. Natural gas was responsible for one quarter (25 percent) of the nation’s energy supply, while coal contributed about 21 percent. Nuclear energy supplied about 9 percent. Renewable sources in the United States totaled about 8 percent.1
