Batteries for Large-Scale Stationary Electrical Energy Storage

Large-scale stationary battery energy storage has been under development for several decades. Several large battery demonstration projects have been built and tested under a variety of electric utility grid applications, and in conjunction with renewable energy sources such as wind and photovoltaics that require energy storage systems. Applications fall into two broad categories: Energy applications and power applications. Energy applications involve storage system discharge over periods of hours (typically one discharge cycle per day) with correspondingly long charging periods. Power applications involve comparatively short periods of discharge (seconds to minutes), short recharging periods, and often require many cycles per day. While many battery technologies have been proposed and developed, only a handful have actually been commercially employed. These include lead- acid, nickel/cadmium, sodium/sulfur, and vanadium-redox flow batteries. Other battery technologies, such as lithium-ion batteries, are less mature and not yet well-developed for these applications.