Rondo Energy is to install a large-scale industrial heat battery at Covestro’s Brunsbüttel site in Germany, as part of efforts to decarbonise process heat in the chemicals sector.
The project, which has now reached the construction phase, centres on a 100MWh “heat battery” designed to convert surplus renewable electricity into high-temperature steam for industrial use.
Unlike conventional electrochemical batteries, the system stores energy as heat in specially engineered bricks. Electricity is used to heat the material, which can then deliver continuous steam for production processes, offering an alternative to fossil fuel-based boilers.
Once operational, the installation is expected to supply around 10% of the site’s steam demand and reduce CO₂ emissions by up to 13,000 tonnes per year, according to the project partners.
Heat battery for industrial decarbonisation
The system is designed to charge when low-cost renewable electricity is available on the grid, storing that energy for later use. This approach allows continuous industrial heat supply despite the intermittency of wind and solar generation.
Industrial steam generation is one of the most energy-intensive and difficult-to-decarbonise aspects of heavy industry. Technologies such as thermal energy storage are increasingly being explored as a way to electrify heat demand while maintaining process reliability.
The Brunsbüttel installation is scheduled to enter operation by the end of 2026 and is supported by funding from Breakthrough Energy Catalyst and the European Investment Bank.
Scaling alternatives to fossil-based heat
Rondo’s system is part of a broader category of electric thermal energy storage (ETES) technologies, which aim to complement battery energy storage by addressing industrial heat demand rather than electricity supply.
By absorbing excess renewable electricity and converting it into dispatchable heat, such systems can also help balance power grids with high shares of variable generation.
For Covestro, the project represents an initial deployment of the technology, with potential for wider rollout depending on performance. The company has positioned the installation as part of its broader strategy to reduce emissions and transition towards climate-neutral production.
For the German state of Schleswig-Holstein, the project represents an important step on the path to climate-neutral transformation of the state. Tobias Goldschmidt, Minister for Energy Transition, Climate Protection, Environment and Nature of the state, said: “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.”
“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.”
Main photo: Mark Helfrich, Member of the German Bundestag, Tobias Goldschmidt, Minister for Energy Transition, Climate Protection, Environment and Nature of the State of Schleswig-Holstein, John O’Donnell, CIO and founder of Rondo Energy, and Dr. Thorsten Dreier, CTO of Covestro, with one of the bricks that will be used in the heat battery. © Covestro
