The promise of vanadium flow batteries

An American laboratory is testing the cutting edge vanadium flow battery, which does away with the cross-contamination hurdle hamstring its peers.


For those of you who know your vanadium, the real question about vanadium flow batteries is: where’s the vanadium going to come from?

But for now, let’s start with the company American Vanadium, which has announced that the new commercially available CellCube vanadium-based flow battery is now undergoing tests at the National Renewable Energy Laboratory in Colorado.

If CellCube passes with flying colours, that will be a significant step forward for the US renewable energy market. Flow batteries have enormous potential for safely and efficiently storing large amounts of intermittent energy, namely wind and solar, with the capability of releasing it quickly on demand even if they have been dormant for long periods.

Among other uses, flow battery facilities could replace conventional fossil fuel-fired “peaking” plants, which are built to satisfy demand spikes but take time to rev up to speed.

The appeal of flow batteries

Flow batteries store energy in the form of two different liquids, contained separately in tanks. The battery discharges when the two liquids are put into motion and flow past each other, creating an electrochemical reaction. The two liquids are typically separated by a membrane, though more recent developments include membrane-free or liquid-metal interaction.

Because the two liquids are separated, flow batteries can store energy for long periods of time without losing their charge. The separate storage components are also a safety feature.

Flow batteries are also relatively easy and inexpensive to scale up in terms of infrastructure, since the main requirement is to build larger tanks along with additional piping and pumps.

For all their advantages, flow batteries have lagged behind the gold standard, lithium-ion, partly because until recently the technology has been bulky and expensive, particularly when it comes to the cost of the membrane.

The promise of vanadium flow batteries

One additional hurdle for the commercialisation of flow batteries is the tendency of the two liquids to cross-contaminate each other, and that’s where vanadium comes in.

A vanadium flow battery only uses one element, vanadium, which resolves the contamination issue.

That’s all well and good, but according to the US Department of Energy, there are still two issues with conventional vanadium flow batteries. They require an expensive polymer membrane, and the electrolyte is a sulfuric acid solution that has a low tolerance for temperature variation and ion saturation, limiting its efficiency.

US researchers have been tackling those problems (hereherehere, and here for example), and the German company Gildemeister Energy Solutions has come up with a little something of its own, the aforementioned vanadium based CellCube. American Vanadium will market the CellCube in the US if all goes well at NREL.

So, what about the vanadium?

That brings us to the real question, vanadium. Vanadium, a silvery gray transition metal, is one of those metals that are key to the development of renewable energy storage solutions and other new clean tech, but in terms of US energy security vanadium is a potential ball and chain. There are currently no vanadium mines in the US, and prices tend to spike wildly on the global market.

That’s where American Vanadium comes in. In 2006 the company began developing a vanadium mine in Nevada, which it claims has the potential to become one of the lowest-cost producers in the world. When last we heard, it was planning to install a vanadium flow battery to power the mine with stored solar and wind energy.

While the new mine doesn’t necessarily insulate the US clean tech market completely from global pricing, it does at least represent a step forward for energy security.

Originally published on CleanTechnica. Reproduced with permission.