Cost and Size Estimates for a Redox Bulk Energy Storage Concept

Abstract

Preliminary capital cost and size estimates were made for an electrochemical bulk energy storage concept. The electrochemical system considered was an electrically rechargeable flow cell with a titanium trichloride |titanium tetrachloride ‖ferric chloride|ferrous chloride redox couple. The preliminary calculations were made to help determine whether the redox‐flow‐cell system has an attractive potential as a bulk energy storage system for power load leveling. With the rise in demand for electric power, the problem facing the electric utility industry of meeting peak power demands has been growing more acute. Because present methods of meeting peak power demands are not entirely adequate the electric utility industry has been interested in new methods for meeting peak power demands. On the basis of preliminary capital cost estimates, size estimates, and several other important considerations, the redox‐flow‐cell system emerges as having great promise as a bulk energy storage system for power load leveling. The size of this system would be less than 2% of that of a comparable pumped hydroelectric plant. The capital cost of a 10 MW, 60 and 85 MW‐hr redox system is estimated to be $190–$330 per kilowatt. This cost compares well with that of competing systems, especially when one considers that for many sites a saving in transmission costs (up to $200 per kilowatt) could be realized with the redox system. This saving could be achieved because the redox systems could be built in various sizes and located near the load centers. The other important features of the redox system contributing to its load‐leveling application are its low adverse environmental impact, its high efficiency, its apparent absence of electrochemically related cycle life limitations, and its fast response.