Australia needs better ways of storing renewable electricity for later

Australia needs better ways of storing renewable electricity for later.

That’s where ‘flow batteries’ can help

Maria Skyllas-Kazacos

As 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. Flow batteries can feed energy back to the grid for up to 12 hours [1] – which is far longer than lithium-ion batteries, that only last for 4-6 hours. I was one of the inventors [2] 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 [3] to expand domestic manufacturing of batteries. This A$500 million strategy will focus on the well-known lithi-um-ion batteries which power phones and cars. But it will also include flow batteries. Batteries are becoming more and more important. They can now power cars, houses and even cities. Huge amounts are being spent on commercialising new battery chemistries to electrify transport and make it possible to green the power grid. To date, most of Australia’s grid-scale batteries [4] use chemistries such as lithium-ion. But as our grid shifts to renewables, we’ll need longer duration storage to eliminate the need for fossil fuel backup generators. That’s a task well suited to flow batteries.
What makes flow batteries different?
Conventional batteries such as lithium-ion batteries store power in their electrodes, commonly a metal.
Flow batteries store power in their liquid electrolytes. The electrolyte solutions are stored in external tanks and pumped through a reactor in which chemical reactions take place at inert electrodes to produce energy.
Flow batteries can be altered to suit
the requirements of a task. One can
change how much power is generated (in kilowatts) and how much energy is stored (in kilowatt-hours). If one wants more storage, it is necessary to increase the volume of electrolytes in the tanks.
As one increases storage capacity, the cost per kWh of stored energy reduces dramatically. This is because it is only necessary to add more liquid electro
lytes, rather than adding entirely new
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battery packs – as occurs with conventional batteries.
This means flow batteries are currently the cheapest way of storing electricity for longer durations (i.e. over 8 hours). Unlike lithium-ion batteries, flow batteries can run for tens of thousands of cycles and the electrolyte used 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 oxid
ation 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, vanad
um flow batteries are now commercially produced by companies in Japan, China and Europe, with several giga-watt hours worth of capacity now installed globally.
China, the world’s largest vanadium producer, has recently approved many large vanadium flow battery projects. In Dec 2024, the world’s largest came online [5] in Dalian China, with 175MW capacity and 700 MWh of storage.
Australia’s first megawatt-scale vanadium flow battery was installed [6] in South Australia in 2023. The project makes use of grid scale battery for storing 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. [7]
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.
The world’s largest vanadium flow battery has come online in China.
The image is by Rongke Power and is licenced by CC BY-NC-ND 2.0
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A 1MW-4 MWh containerized vanadium flow battery owned by Avista Utilities, and made by UniEnergy Technologies. Source: Wikimedia, licenced by CC BY-SA 4.0
In 2023, Townsville became home to Australia’s first factory [8] for producing vanadium electrolyte.
Iron and zinc
Flow batteries can be built from many different chemistries. Two other promising chemistries are iron-iron and zinc bromide.
Iron flow batteries have been under development [9] in the United States since 2011. These cells use iron, salt and water, avoiding the need for vanadium.
In Australia, Queensland-based company ESI Asia Pacific is planning to develop their own iron flow batteries at a new factory in Maryborough once construction is complete in 2026.
While iron is plentiful and cheap, these batteries rely on high purity iron chloride to reduce iron corrosion. This may mean electrolytes cost significantly more than expected. Field testing data is limited to date.
Zinc bromine batteries use a solution of zinc – a metal – and bromine, an
element extracted from sea water. The chemistry implies that each cell has a higher electrical output than other flow batteries, but this advantage comes with a challenge – finding ways to stop the growth [10] of tree-like dendrites inside the cell, which phenomenon can disrupt energy production or trigger short-circuits.
Battery-powered future?
Creating a larger Australian battery industry will take time and funding. But the demand for batteries will skyrocket globally [11] in coming years, across the electricity and transport sectors.
As we work to electrify road transport, the demand for electricity [12] will increase, in addition to the demand for lithium-ion batteries – now ubiquitous in the construction of electric vehicles.
As one of the world’s major producers of lithium, Australia could also manufacture lithium batteries, for domestic use or as an export industry. However to compete globally, Australia would need to embrace automation.
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Vanadium redox flow battery, invented by Prof Maria Skyllas-Kazacos, at the UNSW, Sydney. Image by RadioTrefoil and licenced by CC BY-SA 4.0
Despite different chemistries, the flow batteries share many common components which could be made locally and boost energy self-sufficiency. The manufacture of flow batteries is time consuming and any manual assembly is expensive. However it is now possible [13] to automate assembly lines, which would reduce manufacturing costs and allow Australian-made batteries to compete more favourably. My colleagues and I are currently working to address this challenge.
Within a decade, Australia could well become a globally competitive battery manufacturer as well as an exporter of
critical minerals. Doing so would help the shift to clean energy, both domestically and around the world.
Source: The Conversation, 3 Jan 2025
https://theconversation.com/australia-needs-better-ways-of-storing-renewable-electricity-for-later-thats-where-flow-batteries-can-help-245570
Republished under creative commons licence.

Dr Maria Skyllas-Kazacos is a Professor Emeritus, School of Chemical Engineering, UNSW Sydney

1. https://www.technologyreview.com/2022/02/23/1046365/grid-storage-iron-batteries-technology/
2. https://www.energy-storage.news/discovery-and-invention-how-the-vanadium-flow-battery-story-began/
3. https://www.industry.gov.au/publications/national-battery-strategy/introduction
4. https://reneweconomy.com.au/big-battery-storage-map-of-australia/
5. https://www.energy-storage.news/rongke-power-completes-grid-forming-175mw-700mwh-vanadium-flow-battery-in-china-worlds-largest/
6. https://yadlamalkaenergy.com/project/
7. https://vanitec.org/vanadium/using-vanadium
8. https://www.veccogroup.com.au/
9. https://essinc.com/iron-flow-chemistry/
10. https://www.sciencedirect.com/science/article/abs/pii/S1364032120301325
11. https://www.iea.org/reports/batteries-and-secure-energy-transitions/outlook-for-battery-demand-and-supply
12. https://www.iea.org/reports/global-ev-outlook-2024/outlook-for-battery-and-energy-demand
13. https://rkpstorage.com/2024/08/22/inside-rkps-gigafactory-revolutionizing-vanadium-flow-battery-production/#