It's still early days in large-scale energy storage but the small projects of today are yielding real-world experience with new technology and grid integration.

Primus Power, a VC-funded flow battery startup, chalks up a small win with an R&D contract to deploy its large-scale energy storage in the Puget Sound Energy (PSE) territory. PSE is partnered along with the Bonneville Power Administration and the DOE's Pacific Northwest National Laboratory. 

Primus is going to deliver two 250-kilowatt energy storage systems to study the potential installation of grid-scale flow batteries in PSE's electrical distribution network. PSE is within BPA’s transmission and balancing region, one with a high penetration of wind power.

“BPA has been collaborating with others in the power industry to help integrate wind into our region and stretch the benefits of our hydro system,” said Terry Oliver, BPA’s chief technology innovation officer in a statement.

Tom Stepien, CEO of Primus Power, said in a release, "Together we will learn the real-world value of storage in the PSE system and demonstrate the differentiation of our energy storage solution.”

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.

Primus was recently 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. That 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 due to be installed in 2014.

Founded in 2009, Primus won $11 million in funding from DBL Investors, I2BF Global Ventures, Chrysalix Energy Venture Capital, and Kleiner Perkins in 2011 along with funding over the years from the DOE, ARPA-E, and the CEC.

Other flow battery players include Prudent Power, Redflow (Australia), Cellstrom (EU), ZBB, EnStorage (Israel), Premium Power, and Deeya.

Forecasts for the energy storage market are disparate, optimistic, and wild ass guesses. 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."

It's been slow going, but the energy storage pilot programs are yielding information. Equipment crews at vendors and utilities are gaining experience at deploying substation-sited storage, co-locating with renewables, as well as in domains such as community energy storage and residential energy storage. Regulators at the state and federal levels are listening. And projects like the Primus/Bonneville flow battery project are aiming to show actual monetizable value from energy storage.


Greentech Media has long covered the energy storage market, which includes technologies such as:

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