Imagine a future where industries no longer need to rely on burning fossil fuels for their essential heating needs—a game-changing shift that could significantly reduce carbon emissions. And this is exactly the innovative path Germany is pursuing right now. Recently, the country has begun deploying a new kind of industrial heat storage system made from heated bricks, often called heat batteries, which are poised to revolutionize how heavy industries generate steam for their operations.
In a significant move, Rondo Energy and Covestro have officially started construction on this pioneering system at Covestro’s chemical plant located in Brunsbüttel, in the northern part of Germany. The core purpose of this project is straightforward yet transformative: to produce clean, dependable steam without the need for natural gas or other fossil fuels. This isn’t just a theoretical solution; it’s a practical, scalable alternative designed to replace decades-old technology—gas-fired boilers—that industries have depended on for continuous, large-scale steam production.
What makes this project particularly exciting is its ability to harness the power of renewable energy, especially during times when electricity prices dip below zero, which happens when there’s an excess of renewable power on the grid. In 2025, Germany experienced this phenomenon for a total of 573 hours—an increase of 25% compared to 2024—meaning there was more surplus renewable energy available than needed. During these periods, Rondo’s system captures this inexpensive electricity to heat special bricks—a technology that has been trusted in steel manufacturing for centuries—and stores the energy in the form of heat.
Then, whenever the plant requires steam for production, the stored heat is released to generate high-temperature, emission-free steam, effectively turning renewable electricity into a steady, reliable energy source. The size of this particular setup is quite substantial: with a capacity of 100 megawatt-hours (MWh), it is scheduled to be operational by late 2026. This installation in Germany will join a similar 100 MWh heat battery that Rondo installed earlier this year in California, making it one of the largest industrial heat storage units in the world. Such projects are backed by influential organizations like Breakthrough Energy Catalyst and the European Investment Bank, emphasizing their potential significance.
Once up and running, this heat battery is predicted to supply roughly 10% of the steam demands at the Brunsbüttel plant and could reduce CO2 emissions by around 13,000 metric tons annually—a substantial environmental benefit. Currently, the plant’s steam is primarily produced using natural gas, so this transition marks a big step toward cleaner, more sustainable industrial practices.
Industry and government officials see this development as a promising glimpse into what’s achievable in an energy landscape increasingly dominated by renewable sources. Tobias Goldschmidt, Schleswig-Holstein’s minister for energy and climate, pointed out that the region’s rapid expansion of renewable energy infrastructure is making such innovative projects possible. This not only boosts energy independence but also helps in reaching climate-neutral goals.
At its core, the technology driving this revolution is surprisingly simple. It leverages tried-and-true heat-storage bricks, which are heated with electricity—similar to methods used in steel production—combined with advanced automation and controls. The stored thermal energy then powers a conventional boiler to produce steam without emitting pollutants, all powered by renewable electricity.
Eric Trusiewicz, CEO of Rondo Energy, emphasizes the significance of this development: "Our partnership with Covestro demonstrates that sustainable industrial heat can be both highly reliable and instrumental in balancing the power grid—while simultaneously building the necessary infrastructure to bolster Europe’s industry and energy independence."
Looking ahead, if the Brunsbüttel project meets expectations, Covestro might opt to implement this technology on a broader scale across its other facilities, paving the way for a cleaner industrial future.
And here’s where it gets controversial—could this approach truly replace all fossil fuel-based heating in industry, or are there limitations and challenges yet to be addressed? What do you think about relying on thermal storage in bricks for such critical applications? Join the conversation and share your opinions—are we on the brink of a sustainable industrial revolution, or are there hurdles we should be wary of?
