Techno-economic analysis of a kilo-watt scale hydrogen-bromine flow battery system for sustainable energy storage

Transitioning to a renewable energy economy requires the widespread integration of solar and wind power, which are intermittent, into the electricity grid. To this goal, it is paramount to develop cost-competitive, reliable, location-independence, and large-scale energy storage technologies. The hydrogen bromine flow battery (HBFB) is a promising technology given the abundant material availability and its high power density. Here, the aim is to perform a comprehensive techno-economic analysis of a 500 kW nominal power/5 MWh HBFB storage system, based on the levelized cost of storage approach. Then, we systematically analyze stack and system components costs for both the current base and a future scenario (2030). We find that, for the base case, HBFB capital investments are competitive to Li-ion battery technology, highlighting the potential of large-scale HBFB market introduction. Improving the stack performance and reducing the stack and system costs are expected to result in ~62% reduction potential in capital investments. The base-case levelized cost of storage, $0.074/kWh, is sufficiently low for a wind-solar storage system to compete with a fossil-based power plant, with potential for reduction to $0.034/kWh in the future scenario. Sensitivity analysis indicates that the levelized cost of storage is most sensitive towards the stack lifetime, which motivates research efforts into advanced electrocatalysts with higher durability and ion-exchange membranes with improved selectivity.