With increased penetration of renewable electricity from wind and solar, that modern electricity grid is expected to be more dynamic as it actively responds to supply and demand of renewable electricity. In this scenario, redox flow batteries are seen as a key technology for longer-term energy storage (time ≥ 4 hours). This SLP is an opportunity to perform a review of various chemistries for flow batteries, compute the levelized cost of storage and determine the key limiting factors that prevent widespread commercialization of this technology.