“Utilities ponder battery storage as solar soars”… Price tag > $400/kWh

Utilities ponder battery storage as solar soars
George Leopold
7/9/2012 10:48 PM EDT

SAN FRANCISCO – Growing electricity generation from by solar and wind energy is flowing into California’s electrical grid, forcing utilities here to begin integrating energy storage technologies into their systems as they seek to offset the peak midday energy generating capacity of these “intermittent renewables” with peak late afternoon energy usage.


While next-generation battery technologies like lithium ion remain too expensive for utilities, Mark Rawson, senior project manager for Sacramento’s Municipal Utility District, said technologies like zinc bromine are approaching the $400/kWh price point utilities need to begin widespread deployment of the storage technology.


EE Times

$400/kWh???  At 12¢/kWh, it would take 3333.33 hours to pay for a 1 kWh zinc/bromine battery.

Will a 1kWh zinc/bromine battery last long enough to pay for itself at 12¢/kWh?

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Zinc Bromine Battery (ZBB)

Technology Description

The zinc/bromine battery is very different in concept and design from more traditional batteries such as the lead/acid battery. The battery is based on the reaction between two commonly available chemicals, zinc and bromine.

The zinc/bromine battery can be repeatedly fully discharged without any damage to the battery and has a life of at least one thousand five hundred charge/discharge cycles. This battery is ideally suited in applications that require deep cycle and long cycle life energy storage. The zinc/bromine battery is predominately made with low cost, recyclable plastics and manufactured with techniques suitable for mass production and at low production costs.

The battery consists of a zinc negative electrode and a bromine positive electrode separated by a microporous separator. An aqueous solution of zinc/bromide is circulated through the two compartments of the cell from two separate reservoirs. The electrolyte stream in contact with the positive electrode contains bromine which is maintained at the desired concentration by equilibrating with a bromine storage medium. The bromine storage medium is immiscible with an aqueous solution containing zinc bromide. All battery components are made from a bromine inert plastic.

Unlike the lead acid and most other batteries, the zinc/bromine battery uses electrodes that cannot and do not take part in the reactions but merely serve as substrates for the reactions. There is therefore no loss of performance, as in most rechargeable batteries, from repeated cycling causing electrode material deterioration. When the zinc/bromine battery is completely discharged all the metal zinc plated on the negative electrodes is dissolved in the electrolyte and again produced the next time the battery is charged. In the fully discharged state the zinc/bromine battery can be left indefinitely.

The zinc/bromine battery offers 2 to 3 times the energy density (75 to 85 watt-hours per kilogram) with associated size and weight savings over present lead/acid batteries. The power characteristics of the battery can be modified, for selected applications. Therefore, the zinc/bromine battery has operational capabilities which make it extremely useful as a multi-purpose energy storage option.

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“The zinc/bromine battery can be repeatedly fully discharged without any damage to the battery and has a life of at least one thousand five hundred charge/discharge cycles.”

With a 1,500 charge/discharge cycles, the break-even electricity rate for a $400/kWh zinc/bromine battery is 27¢/kWh.  I’m currently paying about 9¢/kWh (retail).

27¢/kWh sounds a lot like…


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