Round-trip Efficiency — Indicates the amount of usable energy that can be discharged from a storage system relative to the amount of energy that was put in. This accounts for the energy lost during each charge and discharge cycle. Typical values range from 60% to 95%.
Response Time — Amount of time required for a storage system to go from standby mode to full output. This performance criterion is one important indicator of the flexibility of storage as a grid resource relative to alternatives. Most storage systems have a rapid response time, typically less than a minute. Pumped hydroelectric storage and compressed air energy storage tend to be relatively slow as compared with batteries.
Ramp Rate — Ramp rate indicates the rate at which storage power can be varied. A ramp rate for batteries can be faster than 100% variation in one to a few seconds. The ramp rate for pumped hydroelectric storage and for compressed air energy storage is similar to the ramp rate of conventional generation facilities.
Energy Retention or Standby Losses — Energy retention time is the amount of time that a storage system retains its charge. The concept of energy retention is important because of the tendency for some types of storage to self-discharge or to dissipate energy while the storage is not in use.
Energy Density — The amount of energy that can be stored for a given amount of area, volume, or mass. This criterion is important in applications where area is a limiting factor, for example, in an urban substation where space could be a limiting constraint to site energy storage.
Power Density — Power density indicates the amount of power that can be delivered for a given amount of area, volume, or mass. In addition, like energy density, power density varies significantly among storage types. Again, power density is important if area and/or space are limited or if weight is an issue.
Safety — Safety is related to both electricity and to the specific materials and processes involved in storage systems. The chemicals and reactions used in batteries can pose safety or fire concerns.
Life span — measured in cycles.
Depth of Discharge (DoD) — Refers to the amount of the battery’s capacity that has been utilized. It is expressed as a percentage of the battery’s full energy capacity. The deeper a battery’s discharge, the shorter the expected life time. Deep cycle is often defined as 80% or more DoD.
Ambient temperature — Has an important effect on battery performance. High ambient temperatures cause internal reactions to occur, and many batteries lose capacity more rapidly in hotter climates.
Post time: Oct-26-2022