Flow batteries are rechargeable batteries where energy is stored in liquid electrolytes that flow through a system of cells. Ion transfer inside the cell (accompanied. This technology strategy assessment on flow batteries, released as part of the Long-Duration Storage Shot, contains the findings from the Storage Innovations (SI) 2030 strategic initiative. The objective of SI 2030 is to develop specific and quantifiable research, development, and deployment (RD&D). It is therefore a very fast-growing sector: according to European Union estimates, it is set to grow by 20% per year in the near future, rising from 12 GWh today to at least 45 GWh by 2030. A growing slice of this market is taken up by long-life storage systems (8-10 hours or more), which are. This is because those sources only generate electricity when it's sunny or windy, ensuring a reliable grid — one that can deliver power 24/7 — requires some means of storing electricity when supplies are abundant and delivering it later when they're not.