Flow-Rate Optimization and Economic Analysis of Vanadium Redox Flow Batteries in a Load-Shifting Application

During China's critical transition toward smart grids, great attention has been devoted to demand response programs and energy storage technologies. Vanadium redox flow batteries (VRBs) are regarded as the most promising storage technology owing to their flexible energy and power capacity configurations. However, the lack of a deep understanding of the economic viability and VRB flow-rate control strategies remains a major barrier to the expansion of VRBs. To investigate the economic viability of VRB-based load shifting under the time-of-use tariffs in China, this paper (1) optimizes VRBs' energy and power capacity to minimize the total cost (electricity bills plus levelized storage cost) for a university campus in Hangzhou, China; (2) proposes a dynamic VRB (dis)charge and electrolyte flow rate control strategy by considering both economics and system efficiency of VRB-based systems; and (3) evaluates the cost-effectiveness of VRBs for load shifting under various storage lifetimes. Simulation results show that the proposed strategy could increase the VRB system efficiency by approximately 3%, limit the electrolyte temperature increment within 3.08 K, and be cost-effective in the near future.