Flow batteries are the future of renewable energy and Australia could be a world leader – if there’s funding

Maria Skyllas-Kazacos for the Conversation
Within a decade, Australia could become a globally competitive battery maker – just as demand for energy storage grows.

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s more and more solar and wind energy enters Australia’s grid, we will need ways to store it for later. We can store electricity in several different ways, from pumped hydroelectric systems to large lithium-ion battery systems. We can also use flow batteries. These are a lesser-known cross between a conventional battery and a fuel cell.

What makes flow batteries different?

Conventional batteries such as lithium-ion store power in their electrodes, commonly a metal.

Flow batteries store power in their liquid electrolytes. Electrolyte solutions are stored in external tanks and pumped through a reactor, where chemical reactions take place at inert electrodes to produce energy.

Flow batteries can be altered to suit requirements of a task. You can change how much power you generate (in kW) and how much storage (in kWh). If you want more storage, you increase the volume of electrolytes in the tanks.

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As you increase storage capacity, the cost per kWh of stored energy decreases dramatically. This is because you only have to add more liquid electrolytes rather than adding entirely new battery packs, as in conventional batteries.

This means flow batteries are currently the cheapest way to store electricity for longer durations (over eight hours). Unlike lithium-ion batteries, flow batteries can run for tens of thousands of cycles and the electrolyte can last much longer – or even indefinitely. One downside is their weight – these batteries are very heavy and are not portable.

To date, zinc bromine and vanadium redox batteries have undergone the most testing and commercial implementation.

Vanadium flow

In the mid-1980s, my colleagues and I pioneered vanadium redox flow batteries at the University of New South Wales. Vanadium is an unusual metal. It can exist in different states of oxidation in the same solution. That means you can run a battery using just one element, instead of two, as in other chemistries. Doing so lets you avoid cross-contamination and gives the electrolyte solution an indefinite life.

After decades of development, vanadium flow batteries are now being commercially produced by companies in Japan, China and Europe, with several GWh worth of capacity now installed globally.

China, the world’s largest vanadium producer, has recently approved many large new vanadium flow battery projects. In December, the world’s largest came online in Dalian, China, with 175MW capacity and 700MWh of storage.

Australia’s first megawatt-scale vanadium flow battery was installed in South Australia in 2023. The project uses grid scale battery storage to store power from a solar farm.

The main challenge to commercialisation has been securing vanadium, which has fluctuated wildly in price and supply due to competing demand from the steel industry.

This is likely to change. Government investment in critical minerals has fast-tracked several new vanadium mines and processing plants. Australia could become a major global vanadium producer in the future. In 2023, Townsville became home to Australia’s first factory producing vanadium electrolyte.

Flow batteries can feed energy back to the grid for up to 12 hours – much longer than lithium-ion batteries, which only last four to six hours.

I was one of the inventors of one of the main types of flow battery in the 1980s. It has taken decades to bring batteries like these to commercial viability. But they are, finally, arriving in earnest.

This year, the Australian government launched a national battery strategy to expand domestic manufacturing of batteries. This $500m strategy will focus on the well-known lithium-ion batteries that power phones and cars. But it will also include flow batteries

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What makes flow batteries different?

Conventional batteries such as lithium-ion store power in their electrodes, commonly a metal.

Flow batteries store power in their liquid electrolytes. Electrolyte solutions are stored in external tanks and pumped through a reactor, where chemical reactions take place at inert electrodes to produce energy.

Flow batteries can be altered to suit requirements of a task. You can change how much power you generate (in kW) and how much storage (in kWh). If you want more storage, you increase the volume of electrolytes in the tanks.

Future fizzles: the promises and predictions for 2025 in Australia that came true (or didn’t)

Read more

As you increase storage capacity, the cost per kWh of stored energy decreases dramatically. This is because you only have to add more liquid electrolytes rather than adding entirely new battery packs, as in conventional batteries.

This means flow batteries are currently the cheapest way to store electricity for longer durations (over eight hours). Unlike lithium-ion batteries, flow batteries can run for tens of thousands of cycles and the electrolyte can last much longer – or even indefinitely. One downside is their weight – these batteries are very heavy and are not portable.

To date, zinc bromine and vanadium redox batteries have undergone the most testing and commercial implementation.

Vanadium flow

In the mid-1980s, my colleagues and I pioneered vanadium redox flow batteries at the University of New South Wales. Vanadium is an unusual metal. It can exist in different states of oxidation in the same solution. That means you can run a battery using just one element, instead of two, as in other chemistries. Doing so lets you avoid cross-contamination and gives the electrolyte solution an indefinite life.

After decades of development, vanadium flow batteries are now being commercially produced by companies in Japan, China and Europe, with several GWh worth of capacity now installed globally.

China, the world’s largest vanadium producer, has recently approved many large new vanadium flow battery projects. In December, the world’s largest came online in Dalian, China, with 175MW capacity and 700MWh of storage.

Australia’s first megawatt-scale vanadium flow battery was installed in South Australia in 2023. The project uses grid scale battery storage to store power from a solar farm.

The main challenge to commercialisation has been securing vanadium, which has fluctuated wildly in price and supply due to competing demand from the steel industry.

This is likely to change. Government investment in critical minerals has fast-tracked several new vanadium mines and processing plants. Australia could become a major global vanadium producer in the future. In 2023, Townsville became home to Australia’s first factory producing vanadium electrolyte.