Comparing Different Methods for Electrical Energy Storage
The Electricity Storage Association provides a useful comparison for different methods for electrical energy storage (via Brian Wang). One significant omission from the list is "Cryonic Energy Storage," which may prove to be the best of the current crop of contenders for now, until "flow batteries" are perfected.
Large -scale stationary applications of electric energy storage can be divided in three major functional categories:
Power Quality. Stored energy, in these applications, is only applied for seconds or less, as needed, to assure continuity of quality power.
Bridging Power. Stored energy, in these applications, is used for seconds to minutes to assure continuity of service when switching from one source of energy generation to another.
Energy Management. Storage media, in these applications, is used to decouple the timing of generation and consumption of electric energy. A typical application is load leveling, which involves the charging of storage when energy cost is low and utilization as needed. This would also enable consumers to be grid-independent for many hours.
Although some storage technologies can function in all application ranges, most options would not be economical to be applied in all three functional categories.
More graphic comparisons from ESA below:
the entire ESA comparison sheet for more information.
Cryonic energy storage has far more potential than compressed air storage, given the phase change energies involved.
Among electric battery storage methods, flow cell batteries are most scalable and versatile in application. Newer approaches to flow cells using more viscous electrolyte media should allow the technology to be used in vehicular power storage applications.