What are the primary sources of energy?

A variety of sources provides the energy consumed by the Unites States. Fossil fuels make up approximately 80% of our energy sources. This includes petroleum products, which are primarily used for transportation, and natural gas and coal, which are primarily used for electrical power generation. The remaining 20% comes in approximately equal proportions from nuclear power and from renewable sources, including hydroelectric, wind, and solar, which are used for electricity generation. Figures 1 and 2 illustrate the breakdown in consumption in the United States in 2014 by major sources.

This energy mix has changed over time as new fuel sources were discovered and technological advances led to new uses for fuel. Up until the 1850s wood was the primary source of fuel used in the United States. At that time coal began to rapidly displace wood as a fuel, both as a source of heating and for steam powered transportation. This trend accelerated with the growth in electrical power generation in the US. Coal, as a percentage of fuel used, peaked in the early 1900s. At that time the use of oil as a transportation fuel began to rapidly increase. The relative percentage of coal, petroleum, natural gas, and hydroelectric energy usage has remained relatively constant since the mid-1900s. More recently nuclear power has entered the mix, and the rise of renewable energy sources over the last several years has been dramatic. Figure 3 shows the total consumption in energy over time from each major source, illustrating these trends, while Figure 4 shows the percent of total consumption from each source.

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