Flow Batteries for Long Duration Energy Storage and Grid Decarbonization

Solar and wind sources are expected to replace fossil fuels in powering grids, but they are intermittent and non-dispatchable, thus requiring electric energy storage to provide reliable power delivery according to load profile. A dramatic growth in storage capacity is forecasted in to face these issues, up to 1.25 TW and 5 TWh by 2050. Pumped hydro is today the largest-capacity form of grid energy storage worldwide, but it is not expected to grow much, due to geographical and environmental issues. Batteries are often indicated as the solution of choice, notably the dominating Li-ion batteries (LIBs), which are expected to continue to expand. However, their use is limited by economically convenient discharge durations, which do not exceed 4 hours, and raw material costs dynamics. Like other batteries, they present issues e.g. life duration, safety and self-discharge. On the other hand, several studies indicate that to achieve full decarbonization Long Duration Energy Storage (LDES) will be essential, i.e. systems with discharge times above eight hours. Flow Batteries (FBs) have the potentials to provide this performance. In this framework, flow batteries (FBs) are emerging as a competitive option for LDES and several other services. They provide independent sizing of energy and power, thus allowing for long discharge times at full power. Their most developed version, the vanadium FB, exhibits very long life, virtually no self-discharge, operation at room temperature and pressure and absence of fires and explosion hazards. The presentation will discuss their potential and challenges and the undergoing research to improve their performance and competitiveness.