The Prospects for Vanadium Redox Flow Battery Technologies in Electrical Power Systems

Abstract

A vanadium redox flow battery consists of acid vanadium sulfate electrolytes with vanadium ions in different oxidation states flowing past each side of an ion exchange membrane. The storage capacity (kWh) and the power rating (kW) are independent design parameters. They can be realized over wide ranges of scale from watts to megawatts. The laboratory prototype batteries described in this paper have a unique architecture with electronic power switching circuits that enable the battery to be charged with variable DC and AC inputs, and to deliver stable DC and AC outputs, without the use of conventional inductive inverters. Applications may include: renewable sources of electrical energy (solar, wind, etc.), load leveling in factories, buildings and the power grid, and power quality control for sensitive electronics. A new method of charging the battery by reduction of the negative electrolyte with biomass crops of sugar or starch, and oxidation of the positive electrolyte with oxygen or air, is also described.