ScienceDaily has the story.
Cheap and safe:
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composed of inexpensive, earth-abundant elements (carbon, oxygen, nitrogen, hydrogen, iron and potassium) dissolved in water. The compounds are non-toxic, non-flammable, and widely available, making them safer and cheaper than other battery systems.
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"The non-toxicity and cheap, abundant materials placed in water solution mean that it's safe -- it can't catch on fire -- and that's huge when you're storing large amounts of electrical energy anywhere near people."
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Because it is non-corrosive, the flow battery system components can be constructed of simpler and much less expensive materials such as plastics.
Scalable:
The tanks (which set the energy capacity), as well as the electrochemical conversion hardware through which the fluids are pumped (which sets peak power capacity), can be sized independently. Since the amount of energy that can be stored can be arbitrarily increased by scaling up only the size of the tanks, larger amounts of energy can be stored at lower cost than traditional battery systems.
Coming very soon:
[...] battery expert who was not part of the Harvard research, agrees that the new technology offers significant advantages over other flow batteries concepts, including "potential very low costs with sustainable materials, high efficiencies at practical power densities, and safe and simple operation." He adds: "It should be expected that this flow battery approach will have a short development and scale-up path for fast commercial introduction."
Utility shills are going to lose sleep, must come up with new lies:
The demand for battery storage is driven by regulatory factors as much as economic ones. In some states, as well as many parts of the world, if it can't be instantaneously used by meeting electricity demand, solar energy incident on solar panels goes to waste unless the electricity is stored. However, in many states, customers have the right to sell electricity produced by rooftop solar panels at high consumer rates under a regulatory scheme called net metering. Under those circumstances, consumers have little incentive to install batteries. But market experts like William W. Hogan, Raymond Plank Professor of Global Energy Policy at Harvard Kennedy School, believe that such policies are ultimately "uneconomic and unsustainable." And as more and more homeowners install solar panels, utilities are opposing requirements to buy electricity from their customers.
Hogan says net metering is one of a series of "regulatory gimmicks designed to make solar more attractive" and predicts that eventually consumers with rooftop photovoltaic panels will lose the option of exchanging electricity for discounts on their utility bills. When that happens, these homeowners have an incentive to invest in battery storage.