Zinc-Ferricyanide: A Model-Validated Cost-Effective Flow Battery for the Grid

Abstract

The world’s electrical grid is increasingly powered by renewable sources, with wind and solar at the helm; indeed, these two renewables are expected to see the foremost and second-most capacity additions into the next decade1,2. Further deployment, however, is still checked by the intermittency of their supply. There is then urgent need for complementary storage technologies that are sufficiently economical, so as not to impinge upon the competitiveness of variable renewables and historically low cost of electricity2. As RFBs approach the market, quantitative methods are needed to assess their efficacy and economy for grid-scale applications. To this end, we prescribe an objective for global optimization within a generalized electrochemical and economic model3. Performance characteristics, robustly scalable, can be validated even at laboratory scales, then combined with bulk pricing for required components into capital cost. To determine pareto optimal design and operating conditions at the desired application scale, we implement a genetic algorithm. This optimization not only simulates costs and efficiencies associated with scale-up of novel batteries, but also enables fair comparison between batteries that may have significantly different performance characteristics and cost structures (Figure 1). The results for state-of-the-art RFBs indicate that model and experimental performance are in agreement, and that zinc-ferricyanide should outshine other RFBs in utility-scale applications. This expeditious integration of experimental and theoretical analyses can thereby help the RFB community to inform the truly cost-effective path forward.