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California Energy Commission awards $227,000 to SMUD for energy storage research; 1MW zinc bromine flow battery

The California Energy Commission awarded $227,000 to the Sacramento Municipal Utility District (SMUD) for a research project demonstrating how energy storage can be integrated into local microgrids.

SMUD will demonstrate a one-megawatt advanced zinc bromine flow battery energy storage system for utility grid applications and validate the potential penetration of the system. The project will demonstrate the benefits of the storage system for load shifting, peak shaving (sending power back to the grid when demand is high), support for microgrid operations, and renewable energy integration.

SMUD plans to set up two demonstration sites using Premium Power Corporation’s energy storage system. One system will be at SMUD’s Sacramento headquarters; the second will serve the Anatolia III SolarSmart Homes community in Rancho Cordova.

Flowing electrolyte systems are typically made up from three sub-systems: cell stacks; an electrolyte tank system; and an electronics and control system. In the Premium Power zinc bromide energy storage system, electrolyte is pumped from two electrolyte reservoirs through the cell stack in two circuits, one for anode half-cells and the other for cathode half-cells.

The electrolyte in the anode loop is commonly called anolyte; the electrolyte in the cathode loop is called the catholyte. Anolyte and catholyte are in contact through microporous cell separators. Although ionic components in the electrolyte can readily pass through the cell separator, bulk mixing of anolyte and catholyte is prevented.

Click to enlarge.Source: Premium Power. Click to enlarge.

Initially the electrolyte is a homogeneous aqueous solution of zinc bromide, zinc chloride, potassium chloride and quaternary organic bromide salts. As the zinc bromide energy storage system is charged, zinc ions are reduced to metal on the anodes, and bromide ions are oxidized to molecular bromine on the cathodes. The anolyte and catholyte gradually develop different compositions. Elemental bromine produced in the cathode half-cells forms a polybromide complex with quaternary salts in the catholyte. The polybromide complex separates from the catholyte aqueous phase as a high density oily liquid phase. This is collected in the bottom of the catholyte reservoir.

The charging process stores chemical energy in separate locations, inside the cell stack as zinc metal and outside the cell stack in the catholyte reservoir as polybromide complex. During discharge these processes are reversed. Zinc metal oxidizes reforming the zinc ion and bromine is reduced to bromide ion. Bromine available in the catholyte for reduction to bromide ion will be consumed in a short period of time unless polybromide complex from the bottom of the catholyte reservoir is fed back into the circulated catholyte. If the complex is not pumped back into the cathode half-cells, the stack discharge voltage will quickly drop to a value too low to provide useful DC power.

The SMUD headquarters system will help improve microgrid operations, emergency operations, and boost peak period campus operation using electricity generated during off-peak hours. The system at SMUD’s substation will be integrated with the Anatolia III SolarSmart Homes community, which will have 600 homes totaling 1.2 MW of photovoltaic generating capacity installed by the time the system is activated. A common control system at SMUD headquarters will control both storage systems to demonstrate fleet control of multiple distributed storage devices.

The total cost of the SMUD project is $5.15 million. The Commission’s funding will supplement a $2.46 million ARRA award that SMUD, along with project partner Premium Power Corporation, received from the US Department of Energy. SMUD is providing $2.46 million for the project.

Funding for the project will come from the Commission’s Public Interest Energy Research (PIER) program. The award is the result of a solicitation where PIER matched American Recovery and Reinvestment Act (ARRA) funds with the goal to bring as much ARRA dollars into California as possible.



An encouraging trend.

Only $227,000.

This only wipes out the taxes paid by 20 or 30 people.

But since only about 50% pay ANY taxes, you could count it as ~ 50. Not too bad, ummm?

And if CA does not fund this, who will? - Indeed.

Lots more California tax payers where these came from.


If this unit were to try and short circuit, a series connected pump would turn off and the battery shut down.
It lends itself to primary safety as the failure mode is benign.
Sounds like a useful and timely addition to smartening the grid.

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