22 Apr 2008   |   News

Redox flow batteries store solar and wind energy

Research lead

Solar and wind energy make an increasingly important contribution to electricity requirements, but a major drawback is that the power they supply does not usually correspond directly to energy demand.

Surplus energy can be stored in lead batteries until it is needed, but the batteries normally have to be replaced after three to five years. Energy can also be conserved by pumped storage plants, but these, too, have a disadvantage in that they have a relatively low rate of efficiency, which means that a lot of energy is lost.

Redox flow batteries offer an alternative to lead batteries and pumped storage plants. They have a comparable energy density, but their service life is nearly ten times as long as that of lead batteries. However, they are quite expensive in relation to their performance and energy density.

Researchers at the Fraunhofer Institute for Chemical Technology ICT in Pfinztal have developed the prototype of a redox flow battery that makes it possible to test various electrode materials, membranes and electrolytes. According to group leader Jens Tübke. “In this way, we can compare different redox systems in the same test set-up. This allows us to work out precisely what are the pros and cons of each system.” Currently, it is not possible to compare the systems on the basis of existing documentation as everyone measures them in a different test set-up.

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