Techno-Economic Comparison of Different Organic Flow Batteries Based on Experimental Data Versus a Vanadium Flow Battery

Abstract

The challenges of climate change are becoming more and more relevant to society. This also increases the need for a wider use of renewable energies, which, due to their fluctuating availability, also increases the need for the possibility of intermediate storage in other forms of energy. Flow batteries (FB) store electrical energy chemically in electrolytes and are scalable in terms of power and energy. This advantage can best be used in stationary applications; flow batteries are one of the most promising technologies here. The capacity of the batteries is largely determined by the active species of their electrolytes which is why this is mostly focused. The success of a technology is primarily related to economic factors. For this reason, it is important to compare the costs of different technologies. All important influencing factors must be taken into account for the different technologies and related to the technical properties such as performance and efficiency. Nearly no results are available for a cost assessment of organic flow batteries, but the large spectrum of organic active species makes it increasingly worth investigating.Therefore, an existing techno-economic model [[1]] based on a 10 kW / 120 kWh vanadium flow battery (VFB) was optimized and a laboratory scale FB for further research was developed. With this laboratory scale FB, a VFB with electrolytes with different molarities was first examined in 3 likewise standardized test cycles, which contain both the behavior at different electrical currents and aging tests. The same tests were then carried out with aqueous organic FBs (AOFB), with MV / 4-HO-TEMPO and AQS / BQDS in different molarities being selected as RedOx pairs. Those AOFBs were analyzed and compared with the results of the lab-scale VFB. In addition to the most examined parameters such as energy density and power density, temperature and cell resistance were examined, too. A system for evaluating the toxicity of electrolytes was also developed in order to be able to include an initial assessment of the social acceptance of such an FB in the evaluation. In this lecture the first results of this techno-economic approach will be presented. In addition, a rating scale for assessing toxicity is also presented. [1] J. Noack, L. Wietschel, N. Roznyatovskaya, K. Pinkwart, and J. Tübke, Energies, 9, 627 (2016). Figure 1