Dr. Conca reports that the latest greatest utility-scale battery storage technology to emerge on the commercial market is the vanadium-redox battery, also known as the vanadium-flow battery. V-flow batteries are fully containerized, nonflammable, compact, reusable over semi-infinite cycles, discharge 100% of the stored energy and do not degrade for more than 20 years. Most batteries use two chemicals that change valence (or charge or redox state) in response to electron flow that convert chemical energy to electrical energy, and vice versa. V-flow batteries use the multiple valence states of just vanadium to store and release charges.
V can exist as several ions of different charges in solution, V(2+,3+,4+,5+), each having different numbers of electrons around the nucleus. Fewer electrons gives a higher positive charge. Energy is stored by providing electrons making V(2+,3+), and energy is released by losing electrons to form V(4+,5+). Flow batteries consist of two tanks of liquid, which simply sit there until needed. When pumped into a reactor, the two solutions flow adjacent to each other past a membrane, and generate a charge by moving electrons back and forth during charging and discharging. There are other technologies for storing intermittent energy, such thermal energy storage. However, the most widely used storage method is pumped hydro storage, which uses surplus electricity to pump water up to a reservoir behind a dam.
Later, when demand for energy is high, the stored water is released through turbines in the dam to generate electricity. Pumped hydro is used in 99 percent of grid storage today, but there are geologic and environmental constraints on where pumped hydro can be deployed. For now, V-flow batteries offer the best deployable, large-battery storage technology developed thus far.
The original URL: https://www.forbes.com/sites/jamesconca/2016/12/13/vanadium-flow-batteries-the-energy-storage-breakthrough-weve-needed/#395ad0a5bde8
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