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Game-changing redox flow battery

Game-changing redox flow battery

  • 13th Jul 2022
  • The Hindu Business Line

Solutions for future energy storage systems in the stationary segment.

Researchers at Indian Institute of Technology, Madras, have developed a 'vanadium redox flow battery' (VRFB) through a project funded by ONGC Energy Centre Trust and the Pudukkottai-based company High Energy Batteries. Redox flow batteries (RFB) promise to become a game-changer for future energy storage systems in the stationary segment.

Dr Kothandaraman Ramanujam of the Department of Chemistry at IIT-Madras notes that "adopting VRFB into the energy distribution chain will ensure continuous power supply from wind and solar farms. Since it utilises an aqueous electrolyte, it is safe and does not get affected by thermal runaway issues. Besides, this can be used as large-scale UPS [uninterrupted power supply] for office buildings".

Transporting the charged electrolyte to remote locations, just like a tanker carrying petrol, will help generate electricity onsite using a simple pumping mechanism without need for the complicated engines used in power generators.

Ramanujam's team successfully demonstrated 1kW/10kWh VRFB using solar power charging. More than 300 cycles (each cycle takes about three days) have been completed using solar charging. The developed VRFB can operate at a high current density with 80-85 per cent efficiency.

Currently, an ion-conducting membrane, called 'Nafion,' is used in the VRFB stack. This constitutes nearly 25 per cent of the system cost. The research group is looking into developing cost-effective ceramic-hydrocarbon-based porous membranes in place of Nafion, says a statement from IIT-Madras. In order to further reduce the cost of RFB, alternatives to vanadium, based on lead and organic redox materials, are being explored.

The group is also working on alternative flow battery chemistries that use abundant lead, zinc, iron and organic redox-active materials. This would bring down the cost of energy storage on par with or lower than the cost of energy production from solar photovoltaics. Currently available energy storage options are more expensive than the cost involved in generating electricity.