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All-Iron Flow Battery

Case Western Reserve University
ARPA-E Award: 
Cleveland, OH
Project Term: 
01/09/2013 to 02/11/2019
Project Status: 
Technical Categories: 
Case Western
Critical Need: 

Our national electric grid has limited ability to store excess energy, so electricity must constantly be over-generated to assure reliable supply. Though wind and solar power are promising clean alternatives to fossil fuels, their natural unpredictability and intermittency make them incapable of delivering the power on-demand necessary to operate today's grid. The U.S. needs technologies that can cost-effectively store renewable energy for future grid use at any location. Flexible, large-scale storage would create a stronger and more robust electric grid by enabling renewables to contribute to reliable power generation.

Project Innovation + Advantages: 

Case Western Reserve University is developing a water-based, all-iron flow battery for grid-scale energy storage at low cost. Flow batteries store chemical energy in external tanks instead of within the battery container. Using iron provides a low-cost, safe solution for energy storage because iron is both abundant and non-toxic. This design could drastically improve the energy storage capacity of stationary batteries at 10-20% of today's cost. Ultimately, this technology could help reduce the cost of stationary energy storage enough to facilitate the adoption and deployment of renewable energy technology.

Potential Impact: 

If successful, Case Western's all-iron flow battery would enable storage from renewable energy sources at a substantially reduced cost and with improved performance compared to today's designs.


A more efficient and reliable grid would be more resilient to potential disruptions.


Electricity generation accounts for over 40% of U.S. carbon dioxide (CO2) emissions. Enabling large-scale contributions of wind and solar power for our electricity generation would result in a substantial decrease in CO2 emissions.


Increases in the availability of wind and solar power would reduce fossil fuel demand, resulting in reduced fuel prices and more stable electricity rates.

Innovation Update: 

(As of May 2018)

Case Western is building a battery with an all-iron flow cell chemistry, a low cost alternative to the incumbent all-vanadium technology. While iron flow systems have been plagued historically by performance limitations, Case Western developed a new technique to increase the surface area of the current collector, increasing performance. By reversibly electroplating iron metal on carbon particles that are suspended in the flowing liquid electrolyte instead of relying on a flat collector plate, the team was able to improve the performance of the materials. The carbon-rich slurry does not settle when flowing or at rest, and changes in the state of charge do not negatively affect the flow of the liquid electrolyte.

The team’s battery is well suited for a variety of application scales because it uses low cost materials and is non-flammable and non-toxic. Case Western has licensed its technology to Fusion Power Systems (FPS), an Australian provider of energy storage systems. FPS is collaborating with Case Western on prototype demonstrations—building the same devices on both continents. FPS aims to develop a commercial product that can be sold globally.


For a detailed assessment of the Case Western project and impact, please click here.


ARPA-E Program Director: 
Dr. Grigorii Soloveichik
Project Contact: 
Dr. Robert Savinell
Release Date: