Energy is defined as the capacity of a body for doing work. The SI unit of energy is the joule. 1 joule is the work done by a force of 1 newton moving a distance of 1 metre in the direction of the force.
The product of power (watts) and duration (seconds). One watt second = one Joule.
All forms of energy fall into two categories, potential and kinetic energy. We can organise different forms of energy within these two categories.
Potential Energy
Stored energy and energy of position.
- Chemical Energy
- Gravitational Potential Energy
- Nuclear Energy
- Stored Mechanical Energy
- Electrical and Electromagnetic
Kinetic Energy
This is motion, motion of atoms, molecules, objects or waves.
- Electrical Energy
- Motion
- Radiant Energy
- Sound
- Thermal Energy
Electrical Energy Consumption
Electrical energy consumption can be calculated by first looking at the electrical power and then looking at the time over which that power is used.
Energy Storage
Device or physical media that store some form of energy to perform some useful operation at a later time.
Energy Density
Energy density measures how much of that stored energy fits into a given mass or volume: gravimetric energy density (Wh/kg) for mass, and volumetric energy density (Wh/L) for volume. Both matter for battery design, since a pack constrained by weight and one constrained by available space will often favour different cell chemistries and formats.
See also: Power vs Energy Density, Cell Gravimetric Energy Density