California-based Rondo Energy has achieved a significant milestone in the energy sector with its Rondo Heat Battery (RHB) entering daily automatic operation. The 100-MWh system, powered by a solar photovoltaic array, is now delivering continuous high-pressure industrial heat and steam to an enhanced oil recovery site operated by Holmes Western Oil Corp. in Kern County, California.
Rondo replaced one of Holmes’ natural gas-fired boilers with a 20-MW solar array paired with its heat battery. The battery operates by heating clay bricks with electricity, generating steam that is used to force oil from the ground. This project sets new records for an industrial heat battery in terms of capacity, round-trip efficiency, and power supply. The system delivers a volume of heat equivalent to 10,000 home heating systems, with storage temperatures above 1,000°C and round-trip efficiency above 97%.
After 10 weeks of operation, the project has met all milestones for daily automatic operation, performance, efficiency, and reliability. “The Rondo Heat Battery is now proven at industrial scale,” said Eric Trusiewicz, CEO of Rondo Energy. “We are 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 Rondo Heat Battery operates independently of the grid, charging during daylight hours and delivering heat 24 hours a day. By replacing gas consumption with the fixed cost of on-site solar power, the project reduces energy cost volatility and regulatory and carbon market exposure. The lower carbon intensity of the customer’s fuel products strengthens competitiveness in low-carbon markets.
Industrial heat accounts for 25% of global final energy use, and Rondo’s technology provides a simple and safe way for manufacturers to reduce costs and slash scope 1 emissions. Unlike heat pumps or electric boilers that need constant power, the Rondo Heat Battery charges using only the six lowest-cost hours of electricity per day—whether from off-grid solar or from the grid.
“The commercialization of the heat battery represents yet another global inflection point for solar & wind power,” said Andy Lubershane, partner at Energy Impact Partners. “Just as electric vehicles opened up the transport market to renewable electricity, heat batteries will open up an even larger new market, industrial heat, which accounts for roughly a quarter of global energy consumption. We’re thrilled that Rondo is leading the way.”
The Rondo Heat Battery’s storage medium uses only brick and wire—abundant, proven materials that can’t catch fire, explode, or cause toxic leaks. Heat batteries replace or drop in alongside industry-standard boilers and seamlessly integrate into existing steam flanges, delivering steam at any conditions at 100+ bar (1450+ PSI). Because it produces no emissions, the Rondo Heat Battery requires no air permits, easing deployment.
Rondo is already developing and operating projects across North America, Europe, Asia, and Australia, with deployments underway for chemicals, biofuels, food and beverage, and cement. The company’s technology scales quickly, requiring no scarce minerals and using only proven industrial components.
This development could significantly impact the energy sector by providing a scalable, efficient, and environmentally friendly solution for industrial heat. As more companies adopt this technology, it could lead to a reduction in carbon emissions and a shift towards renewable energy sources. The success of Rondo’s Heat Battery could also spur innovation in energy storage technologies, driving further advancements in the field.