Scientists at IIT Madrasin India have developed a kilowatt VRFB to store electricity generated by wind and solar projects.

The researchers claim to have developed a cheaper and faster way to assemble the field-flow layers of the membrane electrode assemblies used in VRFB, which is better than conventional assemblies.

“The system is the first of its kind built in India and can be deployed directly on an industrial-scale stack for grid-level storage, and the effectiveness of the new design has been tested experimentally.” they said.

The scientists say the system has a power rating of 5 kilowatts, a peak power of 8 kilowatts, and a storage capacity of 25 kilowatts. It has an energy density of 30-40 WH per liter and round-trip efficiency of more than 70% at rated power and 60% at peak power.

The researchers said the tests confirmed that the vanadium – sulfuric acid electrolyte used with the new flow field plates and its performs are better than conventional graphite plates with the same flow field parameters.

Ravendra Gunlapalli, a researcher ,said: ‘Energy storage capacity can be easily increased by increasing the volume of electrolytes in the tank, or by adding new tanks while maintaining the same number of stacks. Similarly, if power levels need to be raised, more chimneys can be connected to the same reservoir.”

Each stack has 16 cells, each of which has an area of 1,500 square centimeters. The electrolyte is made of vanadium sulphate hydrate and the electrode is made of graphitized carbon felt.

The researchers used three-dimensional complex geometry and grid cells for CFD simulations to study flow distribution and total pressure drop within cells.

“The combination of experiments and simulations of cell size in the 400-1500 square centimeter range in several types of flow fields has not been reported in the literature and constitutes a major contribution to the current work,” they said. The improved understanding generated from these comprehensive studies has led to two patented innovations tested at the cellular and stack levels.

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