Jan 13, 2014

Low-cost materials could make storing hours of power from a wind farm economically feasible

Harvard University researchers say they've developed a new type of battery that could make it economical to store a couple of days of electricity from wind farms and other sources of power. The new battery, which is described in the journal Nature, is based on an organic molecule—called a quinone—that's found in plants such as rhubarb and can be cheaply synthesized from crude oil. The molecules could reduce, by two-thirds, the cost of energy storage materials in a type of battery called a flow battery, which is particularly well suited to storing large amounts of energy.

The energy storage materials account for only a fraction of a flow battery's total cost. Vanadium, the material typically used now, costs about $80 per kilowatt-hour. But that's high enough to make hitting the $100 target for the whole system impossible. Michael Aziz, a professor of materials and energy technologies at Harvard University who led the work, says the quinones will cut the energy storage material costs down to just $27 per kilowatt-hour. Together with other recent advances in bringing down the cost of the rest of the system, he says, this could put the DOE target in reach.

Studies indicate that one to two days' worth of storage is required for making solar and wind dispatchable through the electrical grid. To store 50 hours of energy from a 1-megawatt power capacity wind turbine (50 megawatt-hours), for example, a possible solution would be to buy traditional batteries with 50 megawatt-hours of energy storage, but they'd come with 50 megawatts of power capacity. Paying for 50 megawatts of power capacity when only 1 megawatt is necessary makes little economic sense.


Liquid energy: Novel energy storage materials flow from the white containers shown here into a fuel-cell like device in the foreground, where they generate electricity.

Nature - A metal-free organic–inorganic aqueous flow battery

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