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Electricity in the United States

Most of the electricity in the United States is produced using steam turbines

A turbine converts the kinetic energy of a moving fluid (liquid or gas) to mechanical energy. In a steam turbine, steam is forced against a series of blades mounted on a shaft. The steam rotates the shaft connected to the generator. The generator, in turn, converts its mechanical energy to electrical energy based on the relationship between magnetism and electricity.

In steam turbines powered by fossil fuels (coal, petroleum, and natural gas), the fuel is burned in a furnace to heat water in a boiler to produce steam.

Most of U.S. electricity is generated using fossil fuels

In 2015, coal was used for about 33% of the 4 trillion kilowatthours of electricity generated in the United States.

In addition to being burned to heat water for steam, natural gas can also be burned to produce hot combustion gases that pass directly through a natural gas turbine, spinning the turbine's blades to generate electricity. Natural gas turbines are commonly used when electricity use is in high demand. In 2015, nearly 33% of U.S. electricity was fueled by natural gas.

Petroleum can be burned to produce hot combustion gases to turn a turbine or to make steam that turns a turbine. Residual fuel oil and petroleum coke, products from refining crude oil, are the main petroleum fuels used in steam turbines. Distillate (or diesel) fuel oil is used in diesel-engine generators. Petroleum was used to generate less than 1% of all electricity in the United States in 2015.

Nuclear power provides about one-fifth of U.S. electricity

Nuclear power plants produce electricity with nuclear fission to create steam that spins a turbine to generate electricity. Most U.S. nuclear power plants are located in states east of the Mississippi River. Nuclear power was used to generate nearly 20% of all U.S. electricity in 2015.

Renewable energy sources provide 13% of U.S. electricity

Hydropower, the source of about 6% of U.S. electricity generation in 2015, is a process in which flowing water is used to spin a turbine connected to a generator.  Most hydropower is produced at large facilities built by the federal government, like the Grand Coulee Dam. The West has many of the largest hydroelectric dams, but there are many hydropower facilities operating all around the country.

Wind power is produced by converting wind energy into electricity. Electricity generation from wind has increased significantly in the United States since 1970. Wind power provided almost 5% of U.S. electricity generation in 2015.

Biomass is material derived from plants or animals and includes lumber and paper mill wastes, food scraps, grass, leaves, paper, and wood in municipal solid waste (garbage). Biomass is also derived from forestry and agricultural residues such as wood chips, corn cobs, and wheat straw. These materials can be burned directly in steam-electric power plants, or they can be converted to a gas that can be burned in steam generators, gas turbines, or internal combustion engine-generators. Biomass accounted for about 2% of the electricity generated in the United States in 2015.

Geothermal power comes from heat energy buried beneath the surface of the earth. In some areas of the United States, enough heat rises close enough to the surface of the earth to heat underground water into steam, which can be tapped for use at steam-turbine plants. Geothermal power generated less than 1% of the electricity in the United States in 2015.

Solar power is derived from energy from the sun. Photovoltaic (PV) and solar-thermal electric are the two main types of technologies used to convert solar energy to electricity. PV conversion produces electricity directly from sunlight in a photovoltaic (solar) cell. Solar-thermal electric generators concentrate solar energy to heat a fluid and produce steam to drive turbines. In 2015, nearly 1% of U.S. electricity generation came from solar power.

Last updated: March 29, 2016

Studying how much electricity is generated and learning about sources used to generate electricity are only two pieces of the U.S. electricity puzzle. Electricity sales and capacity also provide important information about U.S. electricity:

  • Generation is the amount of electricity produced over a period of time. 
  • Capacity is the maximum level at which electric power can be supplied at a point in time.
  • Sales include the amount of electricity sold to customers over a period of time. 

Did you know?

About two-thirds of the energy used to generate, transmit, and distribute electricity is lost at power plants and in power lines.

Electricity generation

In 2015, net generation of electricity in the United States was about 4,087 billion kilowatthours (kWh), and about two thirds was generated using fossil fuels (coal, natural gas, and petroleum):

  • Coal—33%
  • Natural gas—33%
  • Nuclear—20%
  • Nonhydroelectric renewables—7%
  • Hydroelectric—6%
  • Petroleum and other—1%

Electricity generation capacity

line graph showing U.S. Electric Power Industry Net Summer Capacity, 2015
Click to enlarge »
Hydroelectric includes conventional and pumped storage hydroelectric. Other renewables includes biomass, geothermal, solar, and wind. The sum of individual percentages may not equal 100% because of independent rounding.

Sufficient capacity is important, because enough electricity must always be produced to meet demand at every moment on the electric power system, or grid.

At most times, many power plants are not generating electricity at their full capacity. There are three major types of generating units that vary by intended usage:

  • A base load generating unit is normally used to satisfy all or part of the minimum, or base, load of the system. A base load generating unit runs continuously, producing electricity at an essentially constant rate. Base load generating units are generally the largest and most efficient of the three types of units.
  • A peak load generating unit is used to meet requirements during the periods of greatest, or peak, load on the system. A peak load generating unit is normally the least efficient of the three unit types.
  • An intermediate load generating unit meets system requirements that are greater than base load but less than peak load. Intermediate load generating units are used during the transition between base load and peak load requirements.

At the end of 2015, the total electricity generation capacity in the United States was about 1.07 billion kilowatts.

Shares of U.S. electricity generation capacity by major energy source at end of 2015:

  • Natural gas—41%
  • Coal—27%
  • Hydroelectric—10%
  • Nonhydroelectric renewables—10%
  • Nuclear—9%
  • Petroleum—4%
  • Other sources—0.4%

Electricity sales

U.S. electricity sales to customers totaled about 3,725 billion kWh in 2015, nearly the same amount as in 2014.

Who buys electricity?

Sales of electricity went to four general types of electric utility customers in 2015:

  • Residential—1,400 billion kWh (38% of electricity sold)
  • Commercial—1,358 billion kWh (36%)
  • Industrial—959 billion kWh (26%)
  • Transportation—8 billion kWh (0.2%)

Who sells electricity?

Electricity was sold by six major categories of providers in 2014 (latest data available at the time of page update):

  • Investor-owned utilities—51%
  • Power marketers—21%
  • Public utilities—14%
  • Cooperatives—11%
  • Nonutility and others—1%
  • Federal power marketing authorities—1%

Last updated: March 29, 2016

Largest U.S. electricity generation facilities by annual net electricity generation

(2014 final data)

Rank Facility name Primary fuel/energy source State Net generation
1 Palo Verde Nuclear Arizona 32,320,917
2 Browns Ferry Nuclear Alabama 26,738,300
3 Oconee Nuclear South Carolina 21,193,381
4 South Texas Project Nuclear Texas 20,651,667
5 Braidwood Generation Station Nuclear Illinois 20,263,665
6 Grand Coulee Hydroelectric Washington 20,261,569
7 West County Energy Center Natural gas Florida 19,764,923
8 Byron Generating Station Nuclear Illinois 19,252,381
9 Limerick Nuclear Pennsylvania 19,077,244
10 Scherer Nuclear Georgia 18,894,546

Source: Form EIA-923 detailed data

Largest U.S. electricity generation facilities by electricity generation capacity

(2014 final data)

Rank Plant name Primary fuel/energy source State Summer capacity
1 Grand Coulee Hydroelectric Washington 7,079
2 Palo Verde Nuclear Arizona 3,937
3 Martin Natural gas, fuel oil Florida 3,695
4 W.A. Parish Natural gas, coal Texas 3,675
5 West County Energy Center Natural gas, fuel oil Florida 3,669
6 Turkey Point Nuclear Florida 3,552
7 Scherer Coal Georgia 3,389
8 Browns Ferry Nuclear Tennessee 3,309
9 Bowen Coal Georgia 3,202
10 Gibson Coal Indiana 3,132

Source: Form EIA-860 detailed data


Last updated: January 7, 2016