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Breakthrough Flow Battery Cell Stack

United Technologies Research Center (UTRC)
ARPA-E Award: 
East Hartford, CT
Project Term: 
09/09/2010 to 09/30/2013
Project Status: 
Technical Categories: 
Graphic of UTRC's technology
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 present major challenges to delivery of the consistent power that is necessary to operate today's grid. The U.S. needs technologies that can 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: 
United Technologies Research Center (UTRC) is developing a flow battery with a unique design that provides significantly more power than today's flow battery systems. A flow battery is a cross between a traditional battery and a fuel cell. Flow batteries store their energy in external tanks instead of inside the cell itself. Flow batteries have traditionally been expensive because the battery cell stack, where the chemical reaction takes place, is costly. In this project, UTRC is developing a new stack design that achieves 10 times higher power than today's flow batteries. This high power output means the size of the cell stack can be smaller, reducing the amount of expensive materials that are needed. UTRC's flow battery will reduce the cost of storing electricity for the electric grid, making widespread use feasible.
Potential Impact: 
If successful, UTRC's redesigned flow battery cell stack would enable energy producers to store power and balance intermittent energy production from renewable energy sources, transmitting it to regions that need energy at any given moment.
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 2016)
With ARPA-E support, UTRC developed, demonstrated, and licensed a high-power all-vanadium battery that has since been commercialized for grid-level energy storage. After demonstrating a flow battery with peak power of nearly 1,400mW/cm2 (a 10x increase over state-of-the-art flow cells), UTRC integrated its cell into a 20kW flow battery system. The system demonstrated high efficiency over 100 cycles with no notable degradation. As of November 2015, UTRC licensed its system to Vinox Energy, which now sells UTRC’s technology in containerized 65kW/400kWh energy storage units. Vinox deployed its first unit to the U.S. Army at Fort Devens, Massachusetts in 2015. The company has raised tens of millions of dollars from Starwood Energy and Vantage Point Capital Partners to further develop and deploy UTRC’s all-vanadium battery. 
During the team’s ARPA-E term, UTRC focused on designing a high-power cell that extracted more energy without increasing the scale of expensive components. The team borrowed heavily from the polymer electrolyte membrane (PEM) fuel cell design, using interdigitated flow field for efficient reactant delivery and incorporating thin electrodes for improved mass transfer and reaction kinetics. After UTRC increased the power density of the cell, the team focused on optimizing the membrane in order to improve the system’s stability and cost. UTRC worked with 3M to fabricate a membrane that maintained high-proton conductivity but offered low permeability to vanadium. This innovative membrane permitted a doubling in operating current density in the UTRC cells, further increasing stack power density and decreasing stack cost.
For a detailed assessment of the UTRC team's project and impact, please click here.
ARPA-E Program Director: 
Dr. Paul Albertus
Project Contact: 
Mr. Michael Perry
Clipper Windpower Technologies
University of Texas, Austin
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Release Date: