The mismatch between the availability of intermittent wind or sunshine and the variable demand is the biggest obstacle to using renewable sources for a large fraction of our electricity. A cost-effective means of storing large amounts of electrical energy could solve this problem.
Flow batteries store energy in chemical fluids contained in external tanks, as with fuel cells, instead of within the battery container itself. The two main components — the electrochemical conversion hardware through which the fluids are flowed (which sets the peak power capacity) and the chemical storage tanks (which set the energy capacity) — may be independently sized. Thus the amount of energy that can be stored is limited only by the size of the tanks. The design permits larger amounts of energy to be stored at lower cost than with traditional batteries.
This looks like a very interesting field of research. Storing power remains one of the challenges for renewable energy sources such as solar and wind. This is especially true if the use is disconnected from the grid, but is even true for grid-connected uses. Especially as increasing the amount of wind and solar energy make it increasingly likely that surplus energy is created at certain times.
The research seems to allow for sensible size home storage setups. At the commercial level the volume needed is very large. Another concern to be addressed is how many cycles the “battery” is good for before it degrades; current experimentation show no degradation after 100 cycles but consumer/commercial usage will need thousands of cycles.
Related: Battery Breakthrough (solid sodium metal mated to a sulphur compound by an extraordinary, paper-thin ceramic membrane) – Energy Storage Using Carbon Nanotubes (2006) – Chart of Wind Power Generation Capacity Globally 2005-2012 – Recharge Batteries in Seconds