Energy in Brief
What are the major sources and users of energy in the United States?
Last Updated: December 29, 2015
The major energy sources consumed in the United States are petroleum (oil), natural gas, coal, nuclear energy, and renewable energy. The major user sectors of these energy sources are residential and commercial buildings, industry, transportation, and electric power. The pattern of energy use varies widely by sector. For example, petroleum provides 92% of the energy used for transportation, but only provides about 1% of the energy used to generate electric power. Understanding the relationships between the different energy sources and their uses provides insights into many important energy issues.
How can different energy sources be compared?
Primary energy includes petroleum, natural gas, coal, nuclear energy, and renewable energy. Electricity is a secondary energy source that is generated using these primary forms of energy. For example, coal is a primary energy source that is burned by electric power plants to generate electricity, which is a secondary source of energy.
Primary energy sources are commonly measured in different units such as barrels of oil, cubic feet of natural gas, and tons of coal. To compare fuels, a common unit of measure is used. The United States uses the British thermal unit, or Btu, to measure the energy content of each energy source.
Total U.S. energy use in 2014 was about 98 quadrillion Btu. One quadrillion equals 1015, or one thousand trillion. One quadrillion Btu, often referred to as a quad, represents about 1% of total U.S. energy use.
In physical energy terms, one quad represents approximately 172 million barrels of oil (equal to nine days of U.S. petroleum use in 2014), 51 million short tons of coal (equal to 20 days of U.S. coal consumption in 2014), or 1 trillion cubic feet of dry natural gas (equal to 14 days of U.S. natural gas use in 2014).
The number of quads used from each primary energy source in 2014 is shown in the pie chart on the right. Petroleum accounts for the largest share of U.S. primary energy consumption, followed by natural gas, coal, renewable energy (including hydropower, wind, biomass, geothermal, and solar), and nuclear electric power.
Which primary energy sources are used in each sector?
Primary energy is used in residential and commercial buildings, in transportation, by industry, and by electricity generating facilities. The bar chart on the right shows the amount of primary energy used in each of these sectors. The electric power sector is the largest user of primary energy, followed by the transportation sector.
The electric power sector uses primary energy to generate electricity. Nearly all electricity is used in buildings and by industry. This means the total amounts of energy used by residential and commercial buildings, industry, and transportation are actually higher than the amounts shown on the bar chart when electricity is included.
In the chart below, the lines connecting the primary energy sources on the left with the demand sectors on the right in the graphic below summarize the links between energy sources and sector users in the United States. For example, because all nuclear energy is used in the electric power sector to generate electricity, and because nuclear represents 22% of the primary energy used by that sector, the line between nuclear energy and the electric power sector shows 100% for nuclear energy in the source column and 22% for electric power in the sector column.
The mix of primary energy sources varies widely across demand sectors. Energy policies designed to influence the use of a particular primary energy source for environmental, economic, or energy security reasons often focus on sectors that are major users of that energy source.
For example, because 71% of petroleum is used in the transportation sector, where it provides 92% of the total primary energy used, policies to reduce petroleum consumption often focus on the transportation sector. These policies usually seek to increase vehicle fuel efficiency or promote alternative fuels. About 91% of coal, but only 1% of petroleum, is used to generate electricity, which means policies affecting electricity generation are likely to have a much larger impact on coal use than on petroleum use.
Some primary energy sources, such as nuclear and coal, are entirely or predominately used in one sector. Others, like natural gas and renewables, are more evenly distributed across sectors. Similarly, while transportation is almost entirely dependent on one fuel (petroleum), the electric power sector uses a variety of energy sources for generating electricity.
Do sources and uses of energy change over time?
Links between sectors and the energy sources consumed in those sectors change over time, but the changes tend to occur slowly. For example, coal was once used extensively as a fuel for heating homes and commercial buildings, but that specific use of coal has decreased to almost nothing in the United States over the past half-century. Although renewable energy's share of the total primary energy consumed in the United States is still relatively small, its use is growing across all sectors. Also, natural gas use in the electric power increased in recent years because of lower natural gas prices, while the use of coal in that sector has declined.
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Did you know?
The electric power sector has seen large changes in the mix of fuels used to generate electricity. Almost 60 years ago, nuclear energy played no role in electric power generation, but in 2014 , nuclear energy accounted for 22% of the energy used to generate U.S. electricity. Petroleum's share of energy used for electricity generation was 1% in 2014, down from a peak of 18% in 1973.
