Commercial successes in power storage

Large capacity electricity storage systems are in daily use around the world, helping to stabilize the electricity delivery infrastructure and minimize the cost of meeting peak-load requirements. These systems typically operate on a diurnal basis: charging with inexpensive utility energy at night and discharging during periods of peak load demand. Notable successes in electric power storage include medium voltage power quality-UPS (uninterruptible power supply) systems, delivering up to 16 MW, used to safeguard entire industrial facilities and recently commissioned Golden Valley Electric Association battery energy storage system (GVEA BESS), the most power battery system, discharging up to 46 MW and with a specified run time of 15 min. The common factor in these successes is that the storage devices work with, rather than compete against conventional generation. This article describes the functions of these systems and examines other emerging applications in power storage, such as the stabilization of wind farm output. It also addresses other power storage technologies that are achieving commercial successes, such as flywheels and supercapacitors.