California Energy Storage Showcase

Zinc Bromide batteries store energy generated from renewable sources when demand is low and provide that energy when demand is high.

California-based Primus Power Corporation has designed, built, field-tested, and is now deploying a low-cost, utility-grade electrical energy storage battery system within the Modesto Irrigation District and connected to the state's grid. Primus additionally plans to collaborate with Raytheon on a microgrid application at the U.S. Marine Corps Air Station in Miramar, California, outside San Diego.

The objective is to demonstrate the primary and secondary application benefits of this technology, including renewable firming, strategic local peak shaving, automated load shifting, and other ancillary services. Primus' technology is based on research from the Electric Power Research Institute which demonstrated that a zinc‐based system could operate at higher power densities than previously thought possible.

Here, the utility intends to use a 1MWh EnergyPod® to aid in the integration of renewables into their power grid. The utility has a new 25 MW solar photovoltaic system and the EnergyPod® will reduce the variability created by this resource on their power grid.

Primus Power originally started prototyping its technology through a $95,000 grant from the California Energy Commission's (Energy Commission) Energy Innovations Small Grant Program. This prototype exceeded industry performance benchmarks, and due to its success, in 2009 the Energy Commission awarded Primus an additional $1 million. Subsequently, Primus has received a total of $20 million in federal government funds from the U.S. Department of Energy, the Advanced Research Projects Agency – Energy, the Bonneville Power Administration and the U.S. Department of Defense's Environmental Security Technology Certification Program.

See additional information about Primus Power.

project photo project photo

Photos courtesy of Primus Power.



Demonstrating the value of energy storage to provide:

  • Reliability
  • Renewable integration
  • Ancillary services

Type of Technology

Flow cell – energy is stored as the electrolyte in the rechargeable electrical energy storage battery system.

Quick Facts

  • Power Capacity Rating: 250 kW
  • Energy Capacity Rating: 1 MWh
  • Discharge Time: 2-7 hours
  • Type of Energy Storage: Zinc Bromine redox flow batter

Key Developers and Partners

  • Primus Power
  • California Energy Commission

Energy Commission Funding



In development, to be completed in the second half of the 2015 fiscal year.


Location of Rechargeable Electrolytes project in California