A residential vanadium flow battery


Munich-based residential vanadium redox flow battery start-up VoltStorage has secured another $7 million from investors including the Bayern Kapital subsidiary of the development bank of Bavaria; family investment house Korys; the EU-backed EIT Innoenergy, New Jersey-based venture capital fund and seed investor SOSV and Zurich power company Energie 360.

The firm claims that its flow battery system can complete more than 10,000 charge cycles without any effect on its capacity and that its electrolyte is a recyclable, non-flammable vanadium solution.

More than 20 flow battery chemistries, including zinc-bromine, zinc-iron, zinc-cerium, and magnesium-vanadium, have been studied — but the most researched and closest to wide commercialization is the vanadium redox flow battery. Vanadium, the dominant cost in that electrolyte, is a metal mined in Russia, China and South Africa with reserves in the U.S. and Canada, and is used predominantly as a steel additive. Flow battery builders include firms such as UET, ViZn, Primus, Sumitomo, Avalon, redT and Form Energy

Flow batteries circulate a liquid electrolyte through stacks of electrochemical cells and have long held the promise of 10-hour durations, tens of thousands of cycles, minimal degradation, and no limitations on depth of discharge. This performance promise has lured venture capital investment and R&D — but so far, the investments have yielded few commercial, competitive flow battery products.

VoltStorage’s modular unit has a continuous power rating of 1.5 kW and nominal energy of 6.2 kWh, according to the product specs. The unit comes with a ten-year warranty.

Market consolidation

In other recent vanadium flow battery news, California’s Avalon and the U.K.’s redT merged their vanadium redox flow battery firms to form Invinity Energy Systems. The new firm is valued at $70 million in a deal that the companies had been threatening for months.

The merger was structured as a reverse takeover of listed company Avalon by private company redT on a share-for-share basis. The newly merged company is focused on solar-plus-storage grid-scale projects.

Long-duration storage always on the cusp of commercialization

Makers of vanadium flow batteries have aimed for mass-commercialization of their longer-duration energy storage for twenty years but have never been able to reach volumes of scale. The steep price drop in lithium ion batteries has not helped market penetration for flow batteries, either.

Lazard, an asset manager, calculates that the levelized cost of storing electricity in some redox flow projects now overlaps with that of lithium-ion batteries, the main competition.

Sales of vanadium-flow batteries are cited by Lazard as growing from double digits to just over 200 MWh of installed storage capacity. Flow battery installations are increasing but megawatts deployed are meager compared to lithium ion.

This content is protected by copyright and may not be reused. If you want to cooperate with us and would like to reuse some of our content, please contact: editors@pv-magazine.com.