In recent months, I’ve come across more work being done in flow batteries than I’ve seen in the prior decade.
I’ve been known in the past to say that fuel cells are kinda like fueled batteries. Well, flow batteries really are fueled-batteries. A traditional chemical battery is one sealed system that charges and discharges chemical elements through a set of electrodes, and the amount of charge/discharge is dictated by the type and volume of chemistry within the battery. In contrast, a flow battery separates the electrodes from the chemistry, which is stored externally from the electrodes in tanks. In so doing, a flow battery delinks the relationship between power (an instantaneous concept) and energy (power over time) that is essentially hard-wired within a chemical battery. In a flow battery, it’s straightforward to expand the energy of a system by adding more to the storage tanks. And, it’s straightforward to add more “fuel” by injecting more of the reactants into the storage tanks.
Because of this, it is natural to think about how flow batteries can improve the range of electric vehicles, which is the focus of this 2009 article from The Economist. However, energy density remains a challenge that could limit the utility of flow batteries for vehicular purposes.
Several flow battery concepts involving different chemistries are being worked on by a number of academic researchers. DOE’s advanced energy R&D shop ARPA-E awarded a team from Lawrence Berkeley Labs to pursue flow batteries. Commercially, perhaps the three most well-known flow battery technology development companies are ZBB (NYSE MKT: ZBB), RedFlow and Primus Power.
Most of these efforts are targeting to apply flow batteries in grid-scale electricity storage at the substation level. This could be an even more impactful role for flow batteries than their use in vehicles: if flow batteries can provide an economic solution for grid-storage, the implications for expanded renewable energy deployment — enabling intermittent wind and solar energy to achieve more than 15% share of power generation — are possibly massive.