Saving energy in periods of low demand for later utilization
Energy Storage can be accomplished by devices or physical media that store energy to perform useful processes at a later time.
Many forms of energy produce useful work, heating or cooling. The energy forms include temperature differences, chemical energy, gravitational potential energy, electricity, latent heat, and kinetic energy. Energy storage typically converts energy forms that are expensive or difficult to store like electricity, kinetic energy, etc., to more conveniently or economically storable forms.
A battery stores readily convertible chemical energy and a hydroelectric dam stores energy in a reservoir as gravitational potential energy. Ice storage tanks store thermal energy in the form of latent heat (ice). Fossil fuels such as coal and gasoline also store energy – ancient energy derived from sunlight by organisms that later died and became buried, and over time they converted into fuels. A wind-up clock stores mechanical energy, in the spring tension.
Most renewable energy sources, such as solar and wind, do not produce continues power. Sometimes these power sources reach high levels of grid penetration, and energy storage becomes one option to provide reliable energy supplies. Energy storage can capture excess electrical energy during periods of low demand and storing it in other forms until again needed on an electrical grid. The energy is later converted back to its electrical form and returned to the grid as needed.
Reliable energy supply creates therefore an increased demand and focus on energy storage, as the intermittent, renewable energy sources are becoming the primary source of power generation.