Rondo

Rondo Energy makes thermal batteries that store electricity as high-temperature heat for industrial customers in cement, chemicals, food processing, and refining. Inside each Heat Battery, intermittent renewable power runs through resistive elements that warm hundreds of tons of refractory brick, the same kind of brick that has been used in steelmaking for more than a century. The stored heat can then be drawn off as hot air or steam at temperatures up to roughly 1,500 degrees Celsius, allowing factories to electrify process heat that would otherwise be supplied by natural gas or coal. The company's first commercial-scale 100 megawatt-hour unit went into service at a Holmes Western Oil Corp site in California's Kern County. Rondo manufactures the batteries through a partnership with Siam Cement Group at a facility in Thailand, with plans to grow annual output to roughly 90 gigawatt-hours. The team is based in the San Francisco Bay Area.