The grant may be subject to renewal beyond a year, depending on performance. The award is part of a $130-million funding effort by ARPA-E through its ‘OPEN 2012’ program, designed to support innovative renewable energy technologies.

Called a flow battery, the technology offers the prospect of cost-effective, grid-scale electrical energy storage based on eco-friendly small organic molecules. Because practical implementation is a core driver for the program, the researchers are collaborating with Sustainable Innovations, LLC, a commercial electrochemical system developer.

“Storage of very large amounts of energy is required if we are to generate a major portion of our electricity from intermittent renewable sources such as wind turbines and photovoltaics,” said lead investigator Michael Aziz, Gene and Tracy Sykes Professor of Materials and Energy Technologies at the Harvard School of Engineering and Applied Sciences (SEAS). “Currently no cost-effective solution exists to this large-scale storage problem. Flow batteries may make stationary storage viable in the marketplace, and that will enable wind and solar to displace a lot more fossil fuel.”

A type of highly rechargable fuel cell, flow batteries are suitable for storing large amounts of electrical energy in the form of liquid chemicals, which are flowed past the electrochemical conversion hardware and stored externally in inexpensive tanks that can be arbitrarily large. This permits the designer to independently size the electrochemical conversion hardware (which sets the peak power capacity) and the chemical storage tanks (which set the energy capacity).

By contrast, in solid-electrode batteries, such as those commonly found in cars and mobile devices, the power conversion hardware and energy capacity are packaged together in one unit, and cannot be decoupled. Consequently they can maintain peak discharge power for less than an hour before being drained. Studies indicate that 1 to 2 days (the cycle of day/night) are required for rendering renewables like wind and solar dispatchable through the current electrical grid.

To store 50 hours of energy from a