Encyclopedia of Electrical Engineering
Encyclopedia of Electrical Engineering

Sources of 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 that becomes kinetic when it is burned.

Common Forms of Energy

Here are the six most common forms of energy.
  1. Chemical energy. This is stored, or "potential" energy. Releasing chemical energy from carbon-based fuels generally requires combustion like the burning of coal, oil, natural gas, or a biomass such as wood.
  2. Thermal energy. Typical sources of thermal energy include heat from underground hot springs, combustion of fossil fuels and biomass (as noted above) or industrial processes.
  3. Kinetic energy. Kinetic energy is movement, which occurs when water moves with tides or flows downstream, or when air moves wind turbines in the wind.
  4. 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.
  5. Solar energy. Energy radiates from the sun and the light rays can be captured with photo-voltaics and semiconductors. Mirrors can be used to concentrate the power. The sun's heat is also a thermal source.
  6. Rotational energy. This is the energy derived from spinning, typically produced by mechanical devices such as flywheels.