Update on the Puerto Rico electric power authority's spinning reserve battery system

The Puerto Rico electric power authority completed start-up testing and began commercial operation of a 20 MW/14 MWh battery energy storage facility in April 1995. The battery system was installed to provide rapid spinning reserve and frequency control for the utility's island electrical system. This paper outlines the needs of an island utility for rapid spinning reserve; identifies Puerto Rico's unique challenges; reviews the technical and economic analyses that justified installation of a battery energy system; describes the storage facility that was installed; and presents preliminary operating results of the facility.