- Energy storage
- is accomplished by devices or physical media that store some form of energy to perform some useful operation at a later time.
A device that stores energy is sometimes called an accumulator such as is used on the London Tower bridge. All forms of energy are either potential energy (e.g. Chemical, gravitational, electrical energy, etc.) or kinetic energy. A wind-up clock stores potential energy (spring tension - mechanical), a battery stores chemical energy, and a hydroelectric dam stores energy in a reservoir as gravitational potential energy. Fossil fuels including coal and gasoline are chemical energy as is the food we eat.