ABSTRACT
Future power systems with the extended uses of distributed generation and renewable energy require the creation of a new utility grid structure. Distributed generation, consisting of small onsite generation and energy storage units are effective solutions under certain conditions and for some types of customers, e.g. emergency or uninterruptible power units. Over the last decades, innovative ideas have been explored in energy storage technologies, ranging in size, capacity, design complexity and targeted applications. Some of energy storage technologies are designed for power system applications, others for lower scale hybrid power systems, while others are intended to perform short-term energy ride through capabilities for critical infrastructure (e.g. communication systems, hospitals or military facilities). Energy storage has become an enabling technology for renewable energy applications and for enhancing power quality and stability in transmission and distribution, having great application potential. Major constraints for renewable energy penetration are availability, intermittency and variability, and energy storage can mitigate such issues. Energy storage choice depends on specific application, and often several energy storage systems are used to increase system reliability, capacity and supply security. The parameters used in comparisons of storage technologies include efficiency, energy capacity and density, run time, costs, response time, lifetime, self-discharge and technology maturity. The most common energy storage technologies include compressed air energy storage, pumped hydropower storage, batteries, fuel cells, flywheels and super-capacitors.
