Flow Batteries : Has Really Large Scale Battery Storage Come of Age ?
The market for electrical energy storage (ES) solutions has been mostly limited to relatively small applications of battery uninterruptible power supply systems (UPS’s) and very large site-specific systems such as pumped hydro storage, two completely different types of ES with separate markets. Flow batteries (FBs) are promising to change that by providing a technology that can potentially span this entire range of applications. Flow batteries have demonstrated providing ES from sub-second local power reliability to hourslong load shaping and price arbitrage functions at the large commercial end-user-scale (500 kW, 520 kWh). Several pilot plants have been built at this scale and early results are positive. In addition, pilot utility-scale systems (12 megawatt, 120 megawatt-hour) are being constructed. The scale and variety of these pilots reflects high confidence in this technology by developers. This paper details technical principles of 2 competing flow battery technologies available in the immediate future, compares their market-readiness, and analyzes economics and market potential for this technology to compete with UPSs as well as play into new commercial load management markets.
An updated review of energy storage systems: Classification and applications in distributed generation power systems incorporating renewable energy resources
The demand of electric energy is increasing globally, and the fact remains that the major share of this energy is still being produced from the traditional generation technologies. However, the recent trends, for obvious reasons of environmental concerns, are indicating a paradigm shift towards distributed generation (DG) incorporating renewable energy resources (RERs). But there are associated challenges with high penetration of RERs as these resources are unpredictable and stochastic in nature, and as a result, it becomes difficult to provide immediate response to demand variations. This is where energy storage systems (ESSs) come to the rescue, and they not only can compensate the stochastic nature and sudden deficiencies of RERs but can also enhance the grid stability, reliability, and efficiency by providing services in power quality, bridging power, and energy management. This paper provides an extensive review of different ESSs, which have been in use and also the ones that are currently in developing stage, describing their working principles and giving a comparative analysis of important features and technical as well as economic characteristics. The wide range of storage technologies, with each ESS being different in terms of the scale of power, response time, energy/power density, discharge duration, and cost coupled with the complex characteristics matrices, makes it difficult to select a particular ESS for a specific application. The comparative analysis presented in this paper helps in this regard and provides a clear picture of the suitability of ESSs for different power system applications, categorized appropriately. The paper also brings out the associated challenges and suggests the future research directions.
Status of the Vanadium Redox Battery Development Program
Redox flow battery systems have been under investigation for use in energy storage application for some time. The early systems had certain limitations such as electrolyte cross-contamination however; the vanadium redox flow battery system does not suffer from such limitations due to the common element in both positive and negative half-cell electrolytes. Various components of the vandium battery have been developed by methods suitable for large-scale commercialisation. A SkW/13kWh system has been installed in a solar demonstration house and its suitability for application in energy self sufficient housing is currently being evaluated. A 4kW/4kWh vanadium battery system has also been installed in a golf cart and initial vehicle trials have shown its viability in traction applications. Presently a 4kW vanadium battery system is under development for evaluation as a back-up battery in submarines.