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Electricity is a secondary energy source

A hand unplugging an electrical appliance from an outlet

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. Electricity is 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. However, 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.

Scientists and inventors have worked to decipher the principles of electricity since the 1600s. Benjamin Franklin, Thomas Edison, and Nikola Tesla made notable contributions to our understanding and use electricity.

Benjamin Franklin demonstrated that lightning is electricity. Thomas Edison invented the first long-lasting incandescent light bulb.

Before 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: April 19, 2019

Preliminary data for the United States for 2018 (except where noted) as of May 2019.

Note: MW = megawatts, MWh = megawatthours, KW = kilowatts, and kWh = kilowatthours

Electricity generation from utility-scale power plants (net generation)

Total net generation 4,177,810 thousand MWh or about 4.18 trillion kWh
Share of total net generation by energy source  
    Natural gas 35%
    Coal 27%
    Nuclear 19%
    Nonhydroelectric renewables 10%
    Hydroelectric (conventional)   7%
    Petroleum and other sources   1%
Number of electricity generators (2017) 21,437
Largest power plant by net generation Palo Verde (nuclear)—31,097,259 MWh or about 31.1 billion kWh

Electricity generation capacity of utility-scale generators (net summer capacity) (2017)

Total net capacity
1,084,370 MW or about 1.08 billion KW
Share of capacity by energy source  
    Natural gas 42%
    Coal 24%
    Nonhydroelectric renewables 12%
    Hydroelectric (total) 9%
        Conventional hydro       7%
        Pumped storage hydro       2%
    Nuclear   9%
    Petroleum   3%
    Other (includes other gases and sources) <1%
   Total may not equal 100% because of independent rounding.
Largest power plant by capacity Grand Coulee Dam (hydroelectric)—7,079 MW

Electricity consumption (end use) and price

Total end use 3,945,507 million kWh or about 3.95 trillion kWh
Share of end use by type  
    Electricity retail sales (total) 96%
    Direct use of electricity   4%
Electricity retail sales and shares by sector 3,801,928 million kWh or about 3.8 trillion kWh
    Residential sector 39%
    Commercial sector 36%
    Industrial sector 25%
    Transportation sector <1%
Largest electric utility by retail sales (within state in 2017) Florida Power & Light Company—108,513,594 MWh or about 108.51 billion kWh
Retail prices by sector (average annual)  
    Residential 12.89 cents per kWh
    Commercial 10.66 cents per kWh
    Industrial   6.93 cents per kWh
    Transportation   9.77 cents per kWh
    Average 10.58 cents per kWh
State retail price rankings (average annual price for all sectors) Highest—Hawaii at 29.22 cents per kWh
Lowest—Louisiana at 7.65 cents per kWh
Average residential monthly consumption (2017) 867 kWh
Average residential monthly bill (2017) $111.67
Largest electric utility by retail sales revenues (within state, 2017) Pacific Gas & Electric Company—$12.4 billion


Emissions from electric power plants (2017)  
    Carbon dioxide (CO2) 1,849,750 thousand metric tons or about 1.85 billion metric tons or about 2.04 billion short tons
    Sulfur dioxide (SO2) 1,657 thousand metric tons or about 1.66 million metric tons or about 1.83 million short tons
    Nitrogen oxides (NOx) 1,506 thousand metric tons or about 1.51 million metric tons or about 1.66 million short tons

Last updated: June 14, 2019