What Are Sources of Electricity That Charge Your Life?

How Electric Energy Is Generated

Wind turbines stand behind a solar power park
••• Sean Gallup/Getty Images News/Getty Images

Have you ever wondered how your phone and other electronic devices are charged? Besides keeping us digitally connected, electricity also saves lives in hospitals, powers industry, and keeps the U.S. economy going. Whether it's a 19th century energy source like coal or a 21st century source like solar, it's worth knowing how electric energy works, how it's generated, and where the juice that powers our lives comes from.

What You Need to Know About Electric Energy

Electric energy is created by the flow of electrons, often called "current," through a conductor, such as a wire. The amount of electric energy created depends on the number of electrons flowing and the speed of the flow. Energy can either be potential or kinetic. A lump of coal, for example, represents potential energy. When coal is burned, its potential energy becomes kinetic energy.

Common Forms of Energy

Here are the six most common forms of energy.

Chemical energy: This is stored, or “potential,” energy. Releasing chemical energy from carbon-based fuels generally requires combustion (e.g., the burning of coal, oil, natural gas, or biomasses like wood).

Thermal energy: Typical sources of thermal energy include heat from underground hot springs, combustion of fossil fuels and biomass, or industrial processes.

Kinetic energy: Kinetic energy is movement. This type of energy can be captured and turned into electricity when water in a river moves through a hydroelectric dam, for example, or when air moves wind turbines.

Nuclear energy: This is the energy stored in the bonds inside of atoms and molecules. When nuclear energy is released, it can emit radioactivity and heat (thermal energy) as well.

Solar energy: Energy radiates from the sun and the light rays can be captured with photovoltaics and semiconductors. Mirrors can be used to concentrate the power. The sun’s heat is also a thermal source.

Rotational energy: This is the energy derived from spinning, typically produced by mechanical devices such as flywheels.

How the U.S. Sources its Energy

As a part of the Department of Energy, the Energy Information Administration (EIA) is tasked with tracking exactly how the U.S. keeps the lights on. The data here is based on energy sources in 2018, and it's an average across all sectors and energy uses:

  • Petroleum (oil) 36%
  • Natural gas 31%
  • Coal 13%
  • Renewable energy 11% (mainly biomass and wood fuel (45%), hydroelectric (23%), wind (22%), solar (8%), and geothermal (2%))
  • Nuclear power 8%

You can dive deeper into the data and find major imbalances between how energy is sourced in different settings. For example, while the oil industry fuels 92% of the transportation sector (think gas for cars), it fuels just 8% of residential electricity.

Here's a full breakdown of where the electricity comes from when the average American turns the lights on in their home or charges their phone in an outlet:

  • Natural gas 43%
  • Retail sales from the electric power sector 42% (the electric power sector accounts for 1% of all petroleum use in the U.S., 35% of natural gas use, 91% of coal use, 56% of renewable energy use, and 100% of nuclear power use)
  • Petroleum (oil) 8%
  • Renewable energy 7%

These figures average out electricity sources across the entire country. If you want more specific information that directly addresses your community, look at the state and territory breakdown of energy usage. Each state's electric power sector draws energy from a unique combination of sources, and those ratios create significant differences in household electricity sources from one state to the next.

For example, Indiana's electric power sector generated 79.5% of its electricity from coal in 2017, while renewable energy sources accounted for 5.9% of power sector production. In Oregon, on the other hand, 76.7% of electric power sector energy came from renewable sources in 2017, and 3.2% came from coal.

What Lies Ahead

As of 2019, the U.S. government expects to see the biggest growth in renewable sources of energy. By 2050, the Department of Energy expects to see a 2.7% increase in renewable energy consumption across the entire economy—and that's not counting hydroelectric or biomass sources. Natural gas is also expected to become a more prevalent source of electricity, with consumption expected to rise by 0.5% by 2050. Other major sources of electricity are expected to become slightly less prevalent by 2050—petroleum consumption is expected to fall by 0.1%, coal by 0.7%, and nuclear by 0.6%.