An accumulator is an energy storage device: a device which accepts energy, stores energy, and releases energy as needed. Some accumulators accept energy at a low rate (low power) over a long time interval and deliver the energy at a high rate (high power) over a short time interval. Some accumulators accept energy at. • • • • Wanger, E C; Willard, W E (June 1981). (report). /. (PDF) from the original on September 24, 2015. Energy storage is the capture of produced at one time for use at a later time to reduce imbalances between energy demand and energy production. A device that stores energy is generally called an or. Energy comes in multiple forms including radiation,,,, electricity, elevated temperature, and. En.