BATTERY ENERGY-STORAGE TECHNOLOGIES

Battery energy storage systems, comprising lead-acid batteries, power conversion systems, and control systems, are in commercial operation around the world They are used by three main groups: power generating utilities; power distributing utilities; and major power consumers (such as electric furnace foundries). The principal advantages of battery energy storage systems to generating utilities include: load leveling; frequency control; spinning reserve; modular construction; convenient siting; no emissions; and investment deferral for new generation and transmission equipment. Power distributing utilities and major power consumers can avoid costly demand changes by discharging their batteries at peak periods and then recharging with lower cost off-peak power (say, at night). Battery energy storage systems are most cost effective when designed for discharge periods of less than 5 h; other systems (for example, pumped water storage) are better suited for longer discharges. It is estimated that by the year 2000 there will be a potential need for 4000 MW of battery energy storage. New construction of five plants totaling 100 MW is presently scheduled for completion by the Puerto Rico Electric Power Authority between 1992 and 1995.