Last week we covered Primus Power and their efforts at commercializing flow batteries for grid-scale energy storage. Energy storage startups like Primus are aiming to become a meaningful part of the smart grid, supporting the flood of renewables penetrating the utility network.

The company just announced today that it has received $11 million funding from DBL Investors, I2BF Global Ventures, Chrysalix Energy Venture Capital, and Kleiner Perkins Caulfild and Byers. Primus is developing a full-scale demonstration system.

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 sulphur (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

Primus Power's flow battery technology is based on a zinc bromine 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 in turn converts chemical energy directly to electricity.

Primus is a 30-employee startup founded in 2009 by Rick Winter, who also was involved with the founding of flow battery startup Deeya Energy. In addition to Primus, there are a number of other flow battery companies making a mark in the industry, including Enervault, Redflow (Australia), Cellstrom (EU), ZBB, EnStorage (Israel), Prudent Energy, Premium Power, and Deeya.

In November 2009, Primus Power was selected by the U.S. DOE to receive a $14 million award as part of a $47 million project to commercialize a 25-megawatt, 75-megawatt-hour energy storage system in Modesto, California as part of the DOE’s Smart Grid Demonstration Program for the Modesto Irrigation District (MID).  Primus has also received $2 million from the ARPA-E and $1 million from the CEC for the MID program.   

Forecasts for the energy 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."

Contrarian 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."

One way energy storage can pay for itself is by substituting for conventional power. The Primus Power irrigation project could effectively replace the need to build a $75 million natural gas project.

Other storage companies to watch are Rubenius, Xtreme Power, and Megawatt Storage Farms. Rubenius plans to build a first-of-its-kind energy storage warehouse in Mexico. It might be the most ambitious new energy storage project ever conceived. Xtreme Power just officially commissioned a 15-megawatt, battery-based energy storage system on First Wind’s 30-megawatt Kahuku Wind project on Oahu, Hawaii. MegaWatt Storage Farms is a storage developer, a new entity -- like a solar developer, except with energy storage. And like most solar developers, they are somewhat technology-agnostic.

Primus remains faced with proving reliability and the business case for its product. It will take years before flow batteries reach beyond demonstration programs and enter genuine utility-scale deployments. Despite the tendency to nerd out and get lost in the technology, the challenge in energy storage is as much in regulatory policy as it is in technology and cost.