Virtualizing Energy Storage Management Using RAIBA

Because of the intermittent nature of renewable energy-based electricity generation, a key building block for a sustainable renewable energy-based electricity infrastructure is cost-effective energy storage management, which is largely determined by the cost of electric batteries. Despite substantial technological advances in recent years, batteries used in consumer devices and electric vehicles are still too expensive to be feasible for large-scale deployment. One promising way to reduce the battery cost of an energy storage system is to leverage retired batteries from electric vehicles. However, because the charging/discharging characteristics of retired batteries tend to vary widely from one another, putting these heterogeneous batteries into the same module or energy storage system pose significant safety risks and efficiency challenges. This paper presents the design, implementation and evaluation of a reconfigurable battery array system called RAIBA that is designed to address the heterogeneity issue in retired battery-based energy storage systems by allowing the inter-battery connectivity to be recofigurable at run time. In addition, RAIBA also enables virtualization of the electrical energy resources in a battery array in the same way as how computing, storage and network resources are virtualized. Empirical measurements on a fully operational RAIBA prototype demonstrate that it can effectively increase the discharge service time by more than 80% under a set of real-world electric load traces.