Techno-economic analysis of Aqueous Organic Redox Flow Batteries: Stochastic investigation of capital cost and levelized cost of storage

Redox Flow Batteries (RFBs) are a versatile and durable type of electrochemical storage and a promising option for large-scale stationary energy storage. Aqueous Organic Redox Flow Batteries (AORFBs) are an innovative category of RFBs that utilize organic species as active molecules in aqueous electrolytes. These species allow for customization of their properties to achieve high technical performance and reduce battery cost. This study presents a comprehensive techno-economic analysis of AORFBs, evaluating their cost metrics and their associated uncertainties. The work modeled both capital cost and Levelized Cost of Storage (LCOS) for RFBs. The model was validated on the Vanadium Redox Flow Battery (VRFB), and it was employed to evaluate the costs for a generic AORFB, using a Monte Carlo technique to incorporate the uncertainty related to the value of critical parameters. Through stochastic analysis, AORFBs are estimated to have an average specific capital cost of 674 €/kWh for 4 h, and 398 €/kWh for 8 h batteries, and probabilities between 16.9% and 29.6% of having lower capital costs compared to VRFBs. AORFBs are estimated to have a current levelized cost, calculated including only the cost of energy lost in the storage due to irreversibility, of about 530 €/MWh for 4 h, and 411 €/MWh for 8 h batteries. The levelized costs of storage, calculated including the total cost of energy charged into the storage, have average values of 663 €/MWh for 4 h, and 543 €/MWh for 8 h batteries. AORFBs have less than 1% probability of having lower LCOS than VRFBs. Current AORFB systems have higher costs compared to state-of-the-art VRFBs, even assuming a low fabrication cost for available organic molecules. This is caused primarily by the AORFBs’ low energy and power densities and high degradation rates. To ensure cost competitiveness with VRFBs, it is essential to identify better-performing organic redox pairs, which should exhibit high open circuit voltage (≥ 1.1 V), should maintain reasonable round-trip efficiency (≥ 71%) while operating at a high current density (≥55mA/cm2). Furthermore, new organic species should have low degradation rates (≤ 0.4 %/day).