Nate Kirchhofer, Cofounder and CEO, BioZen Batteries, Inc.

David Ridley, Consultant, CleanTech Strategies

Eric Hostetler, Senior Research Engineer, ENTEK

Flow batteries differ from “solid” batteries such as lead-acid and lithium-ion, in that energy is stored not in components of the electrochemical conversion device itself, but rather in tanks containing liquid electrolytes which are pumped between the tanks and the conversion device. Thus, the major components of flow batteries are electro-chemical conversion devices or “stacks” (including membranes, electrodes, bipolar plates, and carbon materials); electrolytes (including a range of active species including metals and carbon-based); tanks, pumps, and other mechanical balance of plant; power electronics; inverter, and enclosure. Each of these major components of a flow battery must be properly designed, and then skillfully integrated into a cost-effective and reliable system. All of this is not easily done.