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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 2017 (except where noted) as of June 2018.

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

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

Total net generation 4,014,804 thousand MWh or 4.01 trillion kWh
Share of total net generation by energy source  
    Natural gas 32%
    Coal 30%
    Nuclear 20%
    Nonhydroelectric renewables 10%
    Hydroelectric (conventional)   7%
    Petroleum and other sources   1%
Number of electricity generators (2016) 20,724
Largest power plant by net generation Palo Verde (nuclear)—32,340,138 MWh or 32.34 billion kWh

Electricity generation capacity of utility-scale generators (net summer capacity) (2016)

Total net capacity
1,074,333 MW or 1.07 billion KW
Share of capacity by energy source  
    Natural gas 42%
    Coal 25%
    Nonhydroelectric renewables 11%
    Hydroelectric (total) 10%
        Conventional hydro       7%
        Pumped storage hydro       2%
    Nuclear   9%
    Petroleum   3%
    Other <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 consumption 3,820,032 million kWh or 3.82 trillion kWh
Share of total consumption by type  
    Electricity retail sales (total) 96%
    Direct use of electricity   4%
Electricity retail sales and shares by sector 3,681,995 million kWh or 3.68 trillion kWh
    Residential sector 37%
    Commercial sector 37%
    Industrial sector 26%
    Transportation sector <1%
Largest electric utility by retail sales (within state in 2016) Florida Power & Light Company—109,449,144 MWh or 109.45 billion kWh
Retail prices by sector (average annual)  
    Residential 12.90 cents per kWh
    Commercial 10.68 cents per kWh
    Industrial   6.91 cents per kWh
    Transportation   9.67 cents per kWh
    Average 10.54 cents per kWh
State retail price rankings (average annual price for all sectors) (2016) Highest—Hawaii at 26.07 cents per kWh
Lowest—Louisiana at 7.75 cents per kWh
Average residential monthly consumption (2016) 897 kWh
Average residential monthly bill (2016) $112.59
Largest electric utility by retail sales revenues (within state, 2016) Pacific Gas & Electric Company—$12.9 billion


Emissions from electric power plants (2016)  
    Carbon dioxide (CO2) 1,928,401 thousand metric tons or 1.93 billion metric tons or 2.13 billion short tons
    Sulfur dioxide (SO2) 1,807 thousand metric tons or 1.81 million metric tons or 1.99 million short tons
    Nitrogen oxides (NOx) 1,630 thousand metric tons or 1.63 million metric tons or 1.80 million short tons

Last updated: August 8, 2018