Primus Power’s flow batteries rake in $11M

Primus Power announced today that it has raised $11 million in its latest round of funding to finance its battery technology, which store energy and provide backup power for large power grids and “smart grids” — power grids that use advanced computer algorithms to efficiently distribute electricity and minimize loss of power.

The batteries can quickly store energy brought in from solar power and wind power projects and release that electricity during peak load times. The batteries work by flowing a conductive solution that has free-floating ions by an electrode in an electrochemical cell. That causes a chemical reaction, inducing a current that can transfer electricity across a power grid. If the process is reversed, the battery stores electricity.

Primus Power is one of several companies funded by the U.S. government’s Advanced Research Projects Agency — Energy (ARPA-E). It’s a part of the U.S. Department of Energy that provides funding for companies that are working on green technology projects that don’t have the same market appeal of more mainstream projects — such as solar power and electric cars. The ARPA-E said it would inject $130 million into green technology companies this year.

Existing investors Kleiner Perkins Caufield & Byers and Chrysalix Energy Venture Capital also participated in the most recent funding round. The company received funding from ARPA-E as part of the agency’s GRIDS project last year, which was created to fund technology capable of improving large-scale power grid energy storage. The U.S. Department of Energy also awarded Primus Power a $14 million grant as part of a $47 million wind energy storage project in California in 2009.

The Hayward, Calif.-based company was founded in 2009 and has 30 employees.