Economic analysis of a new class of vanadium redox-flow battery for medium- and large-scale energy storage in commercial applications with renewable energy

Interest in the implement of vanadium redox-flow battery (VRB) for energy storage is growing, which is widely applicable to large-scale renewable energy (e.g. wind energy and solar photo-voltaic), developing distributed generation, lowering the imbalance and increasing the usage of electricity. However, a comprehensive economic analysis of the VRB for energy storage is obscured for various commercial applications, yet it is fundamental for implementation of the VRB in commercial electricity markets. In this study, based on a new class of the VRB that was developed by our team, a comprehensive economic analysis of the VRB for large-scale energy storage is carried out. The results illustrate the economy of the VRB applications for three typical energy systems: (1) The VRB storage system instead of the normal lead-acid battery to be the uninterrupted power supply (UPS) battery for office buildings and hospitals; (2) Application of vanadium battery in household distributed photo-voltaic power generation systems; (3) The wind power and solar power stations equipped with the VRB storage systems. The economic perspectives and cost-benefit analysis of the VRB storage systems may underpin optimisation for maximum profitability. In this case, two findings are concluded. First, with the fixed capacity power or fixed discharging time, the greater profit ratio will be generated from the longer time or the larger capacity power. Second, when the profit ratio, discharging time and capacity power are all variables, it is necessary to find out the best optimisation result containing the highest profit ratio, the lowest capacity power and the shortest payback years. After the algorithm, it can be concluded that when t = 8 h (including 3 h high peak period and 5 h peak period), and P = 94.7 MW, the shortest years of payback period are 3.4 years, and the profit ratio is 196.5%.