As the world accelerates its shift to renewable energy, a key challenge persists: how to store solar and wind power for use when the sun isn’t shining and the wind isn’t blowing.

Now, researchers say long-duration energy storage (LDES) batteries could be the breakthrough needed to ensure a reliable, low-carbon energy future.

Unlike conventional battery storage, which can be costly and limited in capacity, LDES technologies are being developed to store electricity for eight, 10, or even 12 hours.

This extended storage capability is critical for smoothing out the intermittent nature of renewables and providing backup power for critical infrastructure.

“One of the key things is enhanced grid stability,” said Associate Professor Chris Menictas, who leads the Energy Storage and Refrigeration Laboratory at the University of New South Wales (UNSW).

“Renewable energy sources like solar and wind are intermittent, meaning they do not produce power all the time, such as at night or when the weather is calm.”

“LDES batteries can store excess electricity and release it when needed, which helps smooth out the energy supply,” Menictas added.

“Then there is the question of resilience and being able to provide power for critical services – like a hospital or maybe even a data centre.”

Several LDES battery technologies are under development, each with unique advantages and challenges. Vanadium flow batteries, pioneered at UNSW by Professor Maria Skyllas-Kazacos in the 1980s, are gaining traction globally.

These batteries use vanadium-based electrolytes and can be easily scaled up, offering long lifespans and minimal degradation.

The world’s largest vanadium flow battery, a 175 MW/700 MWh system, was recently completed in Dalian, China.

Lithium-ion batteries, already popular in electric vehicles and consumer electronics, offer high energy density and rapid response but degrade faster and rely on scarce raw materials.

Iron flow and organic flow batteries, still largely in the research phase, promise lower costs and environmental impacts but face hurdles in energy density and scalability.

“There isn’t necessarily one best energy storage solution,” said Professor Jie Bao, Director of the ARC Research Hub for Integrated Energy Storage Systems at UNSW.

“There are different use cases and each of them might have a different solution.

“The different technologies can also be complementary, and can be implemented in tandem and properly coordinated.”

Despite their promise, LDES batteries face significant barriers to widespread adoption.

High upfront costs, supply chain constraints for critical minerals, and the need for further research and development remain major hurdles.

Environmental impacts also vary by technology, with some batteries dependent on mining rare elements and others offering more sustainable, recyclable designs.

Still, experts agree that LDES will be crucial in enabling grids to handle more renewable energy, reduce carbon emissions, and provide resilient backup during emergencies.

With continued innovation and investment, these technologies could soon play a defining role in the world’s clean energy transition.