Origin to trial 12-hour redox flow battery at site of Australia’s biggest coal generator

Australian energy utility Origin Energy says it is going to trial a long duration redox flow battery technology at the site of its Eraring coal generator, and has also spent $4 million buying a five per cent stake in the Newcastle-based technology developer, Allegro Energy.

Origin says that because Allegro’s redox flow battery (RFB) is water based, it is safer and more environmentally friendly than other battery technologies. It also contains no scarce materials, and is completely recyclable.

The redox flow battery – which features a closely guarded electrolyte – will be trialled as a supplement to the huge Eraring battery that will at least partially replace the 2.8GW Eraring coal plant that is currently scheduled to close in August, 2025.

The first stage of the Eraring battery will feature two hours of lithium ion battery storage – 460MW and 920MWh – although it is planned to extend this to up to four hours of storage over time – 700MW and 2,800MWh.

The redox flow battery can offer 12 hours of storage, and Origin intends to trial a small eight hour version sized as a 100kW (800kWh) module at the Eraring site. It will be the first commercial test of the technology.

If that is successful, Origin says it plans to build a 5MW, 60MWh redox flow battery, although the location of that bigger facility is not confirmed, and may not be at Eraring.

“We believe long duration storage will ultimately play an important role in the energy mix, and we look forward to watching the progress of this trial and seeing how this technology could complement other storage projects within Origin’s portfolio,” said Greg Jarvis, the head of Origin’s energy supply and operations.

“Long duration storage could supplement the high demand peak period covered by the 460MW Eraring battery currently under development and add to the overnight generation availability provided by the Shoalhaven (pumped) Hydro Scheme.”

Jarvis said that the Allegro technology is very promising. “It is also particularly pleasing for Origin to work with an innovative, local firm as we look to further transform the Eraring site for the future,” Mr Jarvis said.

The move is potentially significant because of the growing need for long duration storage. That was expected to be provided by pumped hydro, but because of the complexities, costs and delays in large civil engineering projects, energy companies are increasingly turning to batteries as a solution.

Already, a NSW tender has secured an Australian-first eight hour battery to be built by German energy giant RWE, and 12-hour batteries – which can be modular and easily replicated through the grid – offer another potentially compelling solution.

Allegro was founded in 2021. The CEO and co-founder, Professor Thomas Nann, says Origin’s support is a powerful endorsement of the company’s proprietary battery technology.

Nann told RenewEconomy that the electrolyte developed by the company is water based – like vanadium redox flow batteries – but can be used with a number of different chemistries.

“For us, this is a great moment. We got Origin’s endorsement because they trust us, they have seen that our technology works,” he told RenewEconomy. He said the trial of the smaller module could last around 18 months.

Once successful, the next stage battery will be built, and the company also plans to build a local “gigafactory” to meet potential demand. The major shareholders are ASX-listed ReNu Energy, a local VC fund called Melt Ventures, and the founders and others.

ReNu was formerly known as Geodynamics, a former “hot rock” geothermal energy hopeful that Origin Energy was once invested in, but had to take big write-downs after the technology failed to deliver on expectations. ReNu is also heavily invested in green hydrogen projects.

Origin says initial work on the RFB trial module is expected to start in August, with the battery to be commissioned in late 2024. Work on the main Eraring two hour lithium battery is expected to begin in July.

The Eraring coal generator has been given an “indicative’ closure date of August, 2025, but delays in new transmission and wind, solar and storage projects is leading to speculation that at least some of its 720MW units may be kept on line, at least for another summer.

The new NSW Labor government has flagged its interest in buying the Eraring coal plant to keep it open for longer, but appears to have gone quiet on that idea now that is has been faced with the complexities of such a purchase.

However, Origin, indicated on Wednesday that it is keeping its options open.

“Origin will continue to assess the market over time, and this will help inform the final timing for closure of all four units at Eraring,” it said in the statement.

“Origin will also continue to actively engage with the market operator, NSW Government, our people, and the local community regarding plans for Eraring’s closure.”

Origin has agreed to an $18.4 billion takeover led by Canada’s Brookfield Asset Management, which in turns intends to hasten the utility’s switch to green energy by spending up to $30 billion on new wind, solar and storage projects over the next decade, in line with a 1.5°C climate target.