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Shining a light on clean energy storage

R&D Now

Curtin’s Hydrogen Storage Research Group (HSRG), part of the Fuels and Energy Technology Group, is delving into chemically-based storage options for solar power to make renewable energy a viable option for powering commercial and heavy industry throughout Australia.

Solar panels in a field with illustrated sun under a glass cup.

Deep within one of Curtin’s most tech-heavy buildings, Professor Craig Buckley and his staff are warming to the idea of creating low cost hydrogen storage technology.

Backed by an Australian Research Council grant, the team is investigating storage options for Concentrated Solar Power (CSP) thermal energy plants. These plants operate by mirrors reflecting sunlight onto a tower where it is converted into heat energy for electricity production.

A lack of viable storage options has long been renewable technology’s Achilles heel, but Buckley is hoping to change that.

He and his team are pinning their research efforts on metal hydrides – a chemical energy storage medium where compounds form by binding hydrogen with a material such as sodium and its alloys.

The CSP thermal energy storage system relies on paired metal hydrides, with a high-temperature hydride (HTMH) acting as the heat storage medium and the lower-temperature hydride (LTMH) storing hydrogen.

At night, and in times of cloud cover, hydrogen is released from the LTMH and absorbed by the HTMH which produces heat used to generate electricity.

Buckley hopes metal hydrides will replace molten salts – the current storage technology for large-scale CSP plants such as the Crescent Dunes solar power tower in Nevada.

Crescent Dunes generates 110 MW hours of power and supplies roughly 75,000 homes with electricity. Metal hydrides could be far more efficient.

“We are trying to replace the molten salts because they are very low energy density at 153 kilojoules per kilogram whereas a metal hydride is between seven to 55 times more energy dense, depending on the hydride used,” he explains.

It costs approximately $110 million to set up roughly 32,000 tonnes of molten salts for Crescent Dunes and HSRG’s cost analysis shows that implementing hydrides as an alternative storage option could be up to 50 per cent cheaper.

While the technology is progressing, it will still be some time before metal hydrides become a viable option.

“We would probably see hydrides rolled out on the market in the next 10-20 years,” Buckley says.

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