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Electricity is a secondary energy source

A hand unplugging an electrical appliance from an outlet

Source: Stock photography (copyrighted)

Compact fluorescent light bulbs use about 25% of the electricity as incandescent light bulbs to produce the same amount of light.
Energy efficient light bulb.

Source: Stock photography (copyrighted)

Electricity is the flow of electrical power or charge. Electricity is both a basic part of nature and one of the most widely used forms of energy.

The electricity that we use is a secondary energy source because it is produced by converting primary sources of energy such as coal, natural gas, nuclear energy, solar energy, and wind energy into electrical power. It also referred to as an energy carrier, which means it can be converted to other forms of energy such as mechanical energy or heat. Primary energy sources are renewable or nonrenewable energy, but the electricity we use is neither renewable nor nonrenewable.

Electricity use has dramatically changed daily life

Despite its great importance in daily life, few people probably stop to think about what life would be like without electricity. Like air and water, people tend to take electricity for granted. But people use electricity to do many jobs every day—from lighting, heating, and cooling homes to powering televisions and computers.

Before electricity became widely available, about 100 years ago, candles, whale oil lamps, and kerosene lamps provided light, iceboxes kept food cold, and wood-burning or coal-burning stoves provided heat.



Prior to 1879, direct current (DC) electricity was used in arc lights for outdoor lighting. In the late 1800s, Nikola Tesla pioneered the generation, transmission, and use of alternating current (AC) electricity, which reduced the cost of transmitting electricity over long distances. Tesla's inventions brought electricity into homes to power indoor lighting and into factories to power industrial machines.

Last updated: October 25, 2017

Preliminary data for the United States for 2016 (except where noted) as of May 2, 2017.

Generation from utility-scale power plants

Total net generation 4,079,079 thousand megawatthours
Electric utility net generation 2,304,081 thousand megawatthours
Share of total net generation by energy source  
    Natural gas 34%
    Coal 30%
    Nuclear 20%
    Hydroelectric   7%
    Nonhydro renewables   8%
    Petroleum and other   1%
Number of electricity generators (2015) 20,068
Largest power plant by net generation (2015) Palo Verde (nuclear)—32,525,595 megawatthours

Generation capacity of utility-scale generators (2015)

Total electricity generating capacity (net summer)
1,064,055 megawatts
Share of capacity by energy source  
    Natural gas 41%
    Coal 26%
    Hydroelectric (total) 10%
        Conventional hydro   7%
        Pumped storage hydro   2%
    Nonhydro renewables 10%
    Nuclear   9%
    Petroleum   3%
    Other <1%
    Total may not equal 100% because of independent rounding.
Largest power plant by capacity (2015) Grand Coulee Dam (hydroelectric)—7,079 megawatts

Consumption and price

Total electricity consumption (end use) 3,852,769 thousand megawatthours
Share of total electricity consumption by type  
Electricity retail sales (total) 96%
Direct use of electricity   4%
Electricity retail sales (shares by sector)
  Residential sector 38%
  Commercial sector 37%
  Industrial sector 25%
  Transportation sector <1%
Largest utility by retail sales (within state in 2015) Florida Power & Light Company—110,327 thousand megawatthours
Retail prices by sector (average annual)  
    Residential 12.55 cents per kilowatthour (kWh)
    Commercial 10.37 cents per kilowatthour
    Industrial   6.75 cents per kilowatthour
    Transportation 9.48 cents per kilowatthour
    Average 10.28 cents per kilowatthour
State retail price rankings (average annual price for all sectors) Highest—Hawaii: 26.87 cents/kWh
Lowest—Washington: 7.40 cents/kWh
Average residential monthly use (2015) 1,177 kilowatthours
Average residential monthly bill (2015) $128.81
Largest utility by retail sales revenues (within state in 2015) Pacific Gas & Electric Company—$12.6 billion


Emissions from power plants (2015)  
    Carbon dioxide (CO2) 2,031,452 thousand metric tons
    Sulfur dioxide (SO2) 2,584 thousand metric tons
    Nitrogen oxides (NOx) 1,824 thousand metric tons

Last updated: May 2, 2017