Selling large-scale energy storage into the U.S. utility market is a bit of a slog. In addition to technology and cost challenges, the regulatory terrain is tricky, and the revenue path for the utility is not clear.

That's why energy storage firms Primus, Xtreme, Silent Power, Stem, and Terrajoule are seeking non-utility applications for energy storage such as behind-the-meter usage or edge cases like fragile island grids or military deployments.

Primus was just awarded a contract by Raytheon’s Integrated Defense Systems (IDS) to provide an energy storage system for a microgrid at the Marine Corps Air Station (MCAS) in Miramar, California. Self-contained microgrids can include energy generation, distribution, energy storage and managed loads. The project is funded by the Environmental Security Technology Certification Program (ESTCP), the Department of Defense's technology validation and demonstration program.

The project will study islanding and reducing peak electrical demand with a 250-kilowatt, 1-megawatt-hour flow-battery allied with an existing 230-kilowatt solar installation. The system is due to be installed in 2014.

The microgrid market is forecast to be a billion-dollar user of energy storage by 2017, according to Pike Research, driven by the military, natural disaster planning, and rising renewable penetration. Military microgrid developers will include SAIC, Lockheed Martin, Power Analytics (formerly EDSA) and General Electric, already in a big microgrid project with the U.S. Marine Corps. Partnerships like General Electric and Arista, Tesla and SolarCity and Silent Power and Hanwha look to unite storage with residential and commercial solar.  

Primus Power's multi-megawatt-hour flow battery technology is based on a zinc halogen system with zinc plating and de-plating. Flow batteries, sometimes called regenerative fuel cells, are a type of rechargeable battery in which electrolyte flows through an electrochemical cell, which converts chemical energy directly to electricity. By re-circulating electrolyte through electrochemical cells, flow batteries promise long cycle lives, though they do tend to suffer in comparison to other technologies (such as lithium-ion) in terms of round-trip efficiency. Other flow battery players include Prudent Power, Redflow (Australia), Cellstrom (EU), ZBB, EnStorage (Israel), Premium Power, and Deeya.

“Primus Power’s energy storage systems can shift, shape and firm electricity. Our systems have the unique combination of safety, cost and performance attributes that make them an ideal choice for microgrids such as Miramar’s," said Tom Stepien, CEO of Primus Power, in a statement.

Primus was founded in 2009 by Rick Winter, who also was involved with the founding of flow battery startup Deeya Energy. The firm won $11 million funding from DBL Investors, I2BF Global Ventures, Chrysalix Energy Venture Capital, and Kleiner Perkins Caulfield and Byers in 2011 along with funding over the years from the DOE, ARPA-E, and the CEC.

Forecasts for the energy storage market are optimistic. Pike Research says the market will be $35 billion in 2020; Piper Jaffray says $200 billion by 2020. David Hawkins of CAISO has been quoted as saying, "I can't see how it's possible to get to 33 percent [renewable power penetration] without significant energy storage resources on the grid."

Opposing views have been voiced by Jim Detmers, the gentleman who called for the rolling blackouts in the California energy crisis of 2001 when he was the COO of CAISO. Here's what he said about energy storage: "If designed to solve problems on the power system side, yes" -- but he added the caveat, "All of those battery companies waiting for an instruction -- that's not providing the right value to the system or the ISO."

The competitor for energy storage in many applications is natural gas -- a formidable opponent. The challenge in energy storage is as much in regulatory policy as it is in technology and cost.

In any case, Primus needs customers and the military has a set of problems that microgrids and low-cost large-scale energy storage might solve.

When a military site like MCAS loses power, "Planes are grounded and training missions are canceled. You can't even open the gates," according to Stepien.

Currently, utility-scale energy storage in the field is limited to pumped hydro, a few large deployments using compressed air energy storage (CAES), hundreds of megawatts of sodium sulfur (NaS) batteries, mostly in Japan, and some experiments with banks of lithium-ion batteries, nickel-cadmium batteries, and regenerative fuel cells (flow batteries).  Greentech Media has long covered the energy storage market, which includes technologies such as:

    • Batteries (Li-ion, NiMh, Zinc Air, NaS, etc.)
    • Flow batteries
    • Flywheels
    • Phase-change materials
    • Ammonia
    • Thermal storage as heat or ice 
    • Hydrogen systems 
    • Compressed air energy storage (CAES)
    • Pumped hydro
    • Superconducting magnetic energy storage (SMES)
    • Ultracapacitors
    • Using off-peak wind energy to synthesize fuels such as gasoline and diesel from CO2 and water

Here's a list of the utility-scale energy storage programs funded by ARRA.