This episode was originally broadcast in June 2024.

As the world transitions away from fossil fuels, one of the biggest challenges is decarbonizing industrial processes that require consistent, reliable sources of energy to produce high-temperatures. Typically these processes run on fossil gas, but now thermal batteries offer a solution by using electricity to store renewable energy in the form of heat.

Anand Gopal, Executive Director of Policy Research at Californian think tank Energy Innovation, joins Baroness Bryony Worthington to discuss his team's research on using thermal batteries to provide heat for manufacturing. Or as he calls them, hot rocks in a box. By storing intermittent solar or wind energy as the heat of molten salts or crushed rocks, thermal batteries can deliver reliable heat on-demand.

While the tech is almost at commercial availability, there's still one big obstacle: cost. In many countries it is still much cheaper to use gas over electricity, and that makes powering up thermal batteries uneconomical. So what needs to be done to employ them at scale? And will they take the wind out of hydrogen's sails? Find out on this week's episode of Cleaning Up.

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