‘World’s largest’ industrial heat battery is online and solar-powered

Rondo Energy has begun commercial operations of what it says is the world’s largest industrial heat battery – a 100 MWh system now operating at a Holmes Western Oil facility in California. Powered entirely by an onsite solar array, the system supplies constant high-pressure steam and heat to the plant, demonstrating how renewable energy can directly power heavy industry.

An industrial heat milestone

During the day, the off-grid solar array charges the Rondo Heat Battery, and the battery delivers stored heat 24/7. After 10 weeks of daily operation, Rondo says the system has met every performance target, achieving over 97% round-trip efficiency and operating at temperatures above 1,000 °C (1,832 °F). The 100 MWh unit provides the same volume of heat as 10,000 household heating systems.

“The Rondo Heat Battery is now proven at industrial scale,” said Rondo CEO Eric Trusiewicz. “We’re already developing and operating heat batteries across four continents and five industries. Our customers are improving their competitiveness and slashing their carbon emissions at the same time.”

The new system runs directly alongside gas-fired boilers, delivering steam through the same infrastructure without retrofits. By using onsite solar to replace natural gas, the project helps Holmes Western Oil hedge against energy price swings and reduce regulatory and carbon market exposure.

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Just bricks and wires

Industrial heat accounts for about 25% of global energy use, from cement kilns to chemical plants. Rondo’s heat battery technology offers a simple way to decarbonize that sector.

Unlike electric boilers or heat pumps that require constant power, Rondo, which is backed by Bill Gates-founded Breakthrough Energy Ventures and utility-backed Energy Impact Partners, says its system only needs the six cheapest hours of electricity each day, from off-grid solar or low-cost grid power, to fully charge.

“Just as electric vehicles opened up transport to renewable power, heat batteries will open up the industrial heat market,” said Andy Lubershane, partner at Energy Impact Partners. “It’s another global inflection point for solar and wind.”

The Rondo Heat Battery stores energy in simple materials – just brick and wire. That means no scarce minerals, fire risk, or toxic leaks. The system drops in beside existing boilers and can deliver steam at pressures above 100 bar (1,450+ psi). Because it produces zero emissions, it doesn’t need air permits, simplifying deployment.

Rondo has projects across North America, Europe, Asia, and Australia. The company says its technology can scale rapidly, thanks to its use of proven, readily available industrial components.

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