USE CASE
Industrial decarbonization using thermal storage: 
Modeling an idealized chemical park supply structure

Overview: Chemical Giant Covestro and Climate Protection

Covestro is one of the world’s leading manufacturers of high-performance polymer materials and a major player in the global chemical industry. The company employs thousands of people worldwide and operates various production sites with a focus on innovation, sustainability, and industrial transformation. Despite a challenging market environment, Covestro remains a pioneer in climate protection through the consistent implementation of its “Sustainable Future” strategy: By 2030, energy consumption per ton produced is to be reduced by 20% compared to 2020—a decisive contribution to the goal of operational climate neutrality by 2035 (Source).

At its Brunsbüttel plant, Covestro is relying on a highly innovative solution: a heat battery made of bricks will be able to store large amounts of electricity from renewable energy sources and provide it as CO₂-free steam on demand. This will enable ten percent of the site’s steam demand to be covered by renewable energy in the future. (Source).

Covestro Chempark Brunsbüttel (Picture Covestro)

 

How do chemical parks plan, simulate, and optimize such energy systems?

From Research to Implementation

In the BMWK-funded research project “TransTES-Chem” (FKZ 03ET1646A-E), DLR, TSK Flagsol Engineering, JPM Ingenieurtechnik, and GFaI e. V.—drawing on the expertise of the chemical companies Covestro and Currenta—worked with TOP-Energy to explore integration options for high-temperature thermal storage systems and power-to-heat plants within an idealized chemical park model (iCV). This generic model enabled general conclusions to be drawn about technology integration without directly mapping specific locations such as Brunsbüttel.

“The biggest challenge with thermal storage in large industrial plants is finding use cases that ultimately result in a viable business case,” explains Dr.-Ing. Stefan Kirschbaum, Head of Energy Systems Engineering at TOP-Energy. “To integrate storage systems meaningfully into complex energy systems, all the advantages of these technologies must be evaluated. In addition to purely operational benefits, such as taking advantage of variable energy costs, the value of greater flexibility and more freedom in choosing energy sources must also be assessed.”

One model to rule them all? General or specific optimization models?

As part of the research project, exemplary energy systems were modeled in TOP-Energy based on expertise from Currenta and Covestro as well as literature data. The goal was to evaluate power-to-heat plants and high-temperature heat storage systems (e.g., molten salt) within an ideal-typical chemical park supply structure (iCV, DOI: 10.1002/cite.202100164)—as a generic model for chemical parks. The ideal-type chemical park supply structure allows for the evaluation of specific technologies without specifically modeling the conditions of a particular site. In this way, it is possible to make general statements about specific technologies for a broad spectrum of chemical parks. The research project has shown that directly charging thermal storage systems with steam is uneconomical in most cases. It makes much more sense to convert cheaply purchased electricity into thermal energy and store it in this form—an approach that specifically exploits fluctuations in the electricity markets. Since the volatility of electricity prices is expected to continue to increase, this advantage is likely to become even more significant in the future.

A pioneer in low-carbon process heat

Covestro has decided to invest in a thermal storage system. At the heart of the solution is the Rondo Heat Battery, which combines centuries-old materials—bricks—with modern automation to store energy in the form of high-temperature heat and release it as needed. Electricity generated from renewable energy sources is converted into heat using electric heating elements. The bricks store large amounts of this heat. Later, the heat stored in the bricks is converted into steam as needed, ensuring a constant supply of emission-free steam at all times. This allows for the flexible use of electricity from renewable sources: surpluses are stored, and the heat supply remains constant—even when wind and solar energy fluctuate.

System diagram from TOP-Energy showing energy flows, storage and steam generation

Sustainability with Measurable Results

This innovative storage solution will cover 10 percent of the total steam demand at the Brunsbüttel site in the future. This will enable annual savings of up to 13,000 tons of CO₂—a significant contribution toward achieving Covestro’s climate goals.

 

Energy Planning with TOP-Energy

 

Using TOP-Energy’s parameter studies, the research efficiently optimized and evaluated thousands of configurations for loading and unloading capacity as well as total capacity. The heat storage and power-to-heat plant models were primarily utilized for this purpose. In addition, gas turbines, steam turbines, and conventional gas boilers were used to model all degrees of freedom in the energy system. The decision between on-site electricity generation and increased steam production was particularly relevant.

Conclusion: TOP-Energy as an enabler for industrial decarbonization

This is the key benefit: demonstrating that TOP-Energy enables a thorough assessment and targeted advancement of the decarbonization of a typical chemical park supply system. At the same time, the modeling illustrates how electricity from renewable energy sources can be efficiently converted into process heat and steam and stored.

This makes it clear that not only can emissions be reduced, but flexibility, supply security, and cost-effectiveness in complex energy systems can also be improved. The added value thus lies in a robust decision-making basis for industrial transformation.