In this study, we focused on a redox flow battery, regarded as one of the promising large scale stationary storage technologies. Specifically, for a state-of-the-art vanadium redox flow battery system of 1 MW / 5 MWh, manufacturing cost was estimated to be 91 JPY/Wh for annual production of 100 MWh in battery capacity. Although the system has a much longer life time than other power storage systems, it is thus still necessary to significantly reduce manufacturing cost.
　In the future, we will explore the possibilities of reducing manufacturing cost by using cheaper, high performance materials for the electrolytes, separators, electrodes, intermediate frames and bipolar plates, as well as by improving manufacturing technology and battery evaluation methodologies.