Covestro and Rondo Energy have marked a milestone in industrial energy innovation with the groundbreaking of a revolutionary heat battery at Covestro’s Brunsbüttel site. 

 

The Rondo Heat Battery stores surplus renewable energy in bricks and delivers continuous high-temperature steam for on-site production — offering a sustainable alternative to fossil fuel-based steam generation.

 

“This project shows how two of Europe’s central challenges can be solved together,” said Eric Trusiewicz, CEO of Rondo Energy. 

 

“As renewable power expands, it increasingly creates daily periods of abundant, low-cost electricity. At the same time, European industry needs reliable, affordable energy to remain competitive. Together with Covestro, we are demonstrating that clean industrial heat can be both highly reliable and a powerful tool for balancing the grid — while building the energy infrastructure needed to strengthen Europe’s industrial base and energy security.”

 

The 100 MWh Rondo Heat Battery (RHB), supported by Breakthrough Energy Catalyst and the European Investment Bank, is set to start operations by the end of 2026. It will produce ten percent of the site’s steam needs, cutting up to 13,000 tons of CO₂ emissions annually.

 

“As an innovation company, we are always excited when we can further develop and test promising ideas that can bring us closer to our goals of a circular economy and climate-neutral production,” said Thorsten Dreier, CTO of Covestro. “The heat battery is such an idea: a new technology that enables us to take another step forward on our path to a sustainable future.”

 

The heat battery pairs centuries-old materials with modern automation. Electrical energy is stored as heat in bricks, driving a conventional boiler to produce emission-free steam. By using renewable electricity, Covestro can ensure a constant, reliable steam supply — a critical component of its production process.

 

For Schleswig-Holstein, the project represents a leap toward climate-neutral transformation. 

 

Tobias Goldschmidt, Minister for Energy Transition, Climate Protection, Environment and Nature of Schleswig-Holstein, said at the ceremony: “The energy transition is Schleswig-Holstein's project of our time. The rapid expansion of renewable energies is a booster for our business location Schleswig-Holstein and makes future-oriented projects like the heat battery possible in the first place. 

 

"Covestro and Rondo impressively demonstrate how they are driving the energy transition forward with innovative strength, technological know-how, and full confidence. Projects like this contribute significantly to energy sovereignty and to achieving our climate neutrality goals.”