Image of the coal fired Navajo Generating Station
on the Navajo Indian Reservation.
In 2015, the United States relied on fossil fuels in the form of coal, natural gas, and petroleum to supply 81.5% of total energy consumption, down 10.8% from 1950 levels. Renewable energy, such as wind, solar, and biofuels, accounted for 9.7% of US energy needs in 2015, up 12.8% from 1950 levels. Nuclear energy supplied 8.6% of total US energy needs, up from 0.0% in 1950.
Renewable and nuclear energy are often referred to as "alternative energy" and accounted for 18.3% of total energy consumption in 2015.
Total Percent of Energy Consumption in the United States by Source, 1950-2015
Fossil Fuel Energy
British Thermal Units (Btu) Conversion Chart
In total, the United States consumed 97.4 quadrillion British Thermal Units (Btu) of energy in 2015. The US Energy Information Agency (EIA) defines a Btu as "[t]he quantity of heat required to raise the temperature of one pound of liquid water by 1 degree Fahrenheit at the temperature that water has its greatest density (approximately 39 degrees Fahrenheit)." Expressing energy consumption in Btu allows for comparisons between fuels that are measured in different units.
For example, renewables such as wind and solar power produce electricity. Electricity is normally measured in a unit called the kilowatthour (kWh) while petroleum (oil) and other liquid fuels are often measured in gallons.
Electricity: 1 kilowatthour = 3,412 Btu
Natural Gas: 1 cubic foot = 1,037 Btu
Motor Gasoline: 1 gallon = 120,476 Btu
Wood: 1 cord (128 cubic feet) = 20,000,000 Btu
Source: US Energy Information Administration (EIA), "Energy Units and Calculators Explained: British Thermal Units," eia.gov, June 13, 2017
Total Energy Consumption in the United States by Source, 1950-2015 (Btu, quadrillions)
According to the EIA, the residential sector is "an energy-consuming sector that consists of living quarters for private households. Common uses of energy associated with this sector include space heating, water heating, air conditioning, lighting, refrigeration, cooking, and running a variety of other appliances. The residential sector excludes institutional living quarters."
Commercial Energy Consumption in the United States by Source, 1950-2015 (Btu, quadrillions)
According to the EIA, the commercial sector is "an energy-consuming sector that consists of service-providing facilities and equipment of: businesses; federal, state, and local governments; and other private and public organizations, such as religious, social, or fraternal groups. The commercial sector includes institutional living quarters."
Industrial Energy Consumption in the United States by Source, 1950-2015 (Btu, quadrillions)
According to the EIA, the industrial sector is "an energy-consuming sector that consists of all facilities and equipment used for producing, processing, or assembling goods. The industrial sector encompasses the following types of activity: manufacturing; agriculture, forestry, fishing and hunting; mining, including oil and gas extraction; and construction. Overall energy use in this sector is largely for process heat and cooling and powering machinery, with lesser amounts used for facility heating, air conditioning, and lighting."
Transportation Energy Consumption in the United States by Source, 1950-2015 (Btu, quadrillions)
According to the EIA, the transportation sector is "an energy-consuming sector that consists of all vehicles whose primary purpose is transporting people and/or goods from one physical location to another. Included are automobiles; trucks; buses; motorcycles; trains, subways, and other rail vehicles; aircraft; and ships, barges, and other waterborne vehicles."
Fuels Used to Generate Electricity in the United States by Source, 1950-2015 (Btu, quadrillions)