T. Hoefel, M. HOFSTAETTER, F. ROESSLER, M. MAYERHOFER and G. KRACKER, Linde Engineering, Munich, Germany
The electrification of steam cracking furnaces provides the potential to reduce direct carbon dioxide (CO2) emissions from steam cracking by more than 95%. In April 2024, the world’s first industrial-scale demonstration plant—featuring two electric cracking furnaces utilizing different heating principles—was successfully started up at BASF’s Verbund site in Germany. Since then, the consortium partnersa responsible for the development of the technologyb have achieved several thousand hours of incident-free operation, providing critical insights into design, reliability and operability under commercially relevant conditions.
The authors’ company executed the engineering, procurement and construction (EPC) of the plant. Lessons learned from both EPC execution and operational performance enable the refinement of scalable design concepts suitable for large-capacity installations. Parallel engineering activities have advanced to a stage that enables commercial deployment. Beyond steam cracking, the underlying electric heating technologies show strong applicability across a broad range of high-temperature industrial processes. This article highlights the demonstrated performance, summarizes scale-up considerations and outlines favorable application scenarios to guide future project development and implementation.
Background. The petrochemical industry accounts for roughly 5% of global CO2 emissions, with steam cracking representing one of its largest individual contributors. Direct CO2 emissions from steam-cracking exceed 300 MMtpy globally,1,2 largely due to the combustion of hydrocarbon fuels required to achieve the high temperatures needed for cracking reactions. Technologies capable of reducing these emissions have become an industry priority.
The steam cracking process demands significant energy. Reaction heat must be supplied at temperatures approaching 850°C (1,562°F) at the cracking coil outlet, while maintaining tube metal temperatures of up to 1,100°C (2,012°F). Today, this energy is predominantly supplied by firing byproduct gas, supplemented by natural gas, in the radiant sections of cracking furnaces. Waste heat is recovered to generate utility steam and preheat feedstock. As a result, the majority of a steam cracker’s direct CO2 emissions originate from the furnaces.
Electrifying the furnaces represents a fundamentally different decarbonization approach compared with strategies that rely on CO2 capture and storage (CCS)—whether applied directly to furnace flue gas or upstream in the production of low-carbon fuels such as blue hydrogen (H2). Together, both approaches contribute important options for achieving deep emissions reductions in the petrochemical and other industrial sectors. CCS-based strategies are essential for decarbonizing existing assets where suitable sequestration and long-term storage infrastructure are available. Electrification avoids the generation of CO2 by eliminating fossil-fuel firing and decouples furnace operation from combustion-related emissions, where low-carbon power is accessible. In regions with abundant low-carbon electricity, electric cracking furnaces can also enhance long-term energy cost stability by reducing exposure to fuel-gas markets and future CO2 transport and storage costs.
Development, demonstration plant EPC and operation. The development of electric cracking furnace (eFurnace) technology is the result of a multi-year collaborationa, combining extensive individual research with joint development work to advance two distinct electric-heating concepts for steam cracking.3,4 Both concepts are based on resistive heating, in which electrical energy is supplied through solid conductors to generate heat via the Joule effect (FIG. 1).
In the indirect heating concept, an electric current is supplied to dedicated heating elements positioned within the coil box. These elements are heated resistively and transfer energy primarily by radiation to the process coils. This arrangement is similar to conventional fired furnace layouts, with the heating elements functionally replacing burners while maintaining a conventional radiant-box geometry.
The direct heating concept applies electric current directly to the process tubes themselves. Here, Joule heating occurs within the conventional coil material, generating the reaction heat inside the tube walls. This configuration minimizes thermal transfer steps and offers unique dynamic and control characteristics.
Pilot testing programs, supported by numerical modeling, were conducted to confirm the feasibility and performance characteristics of both electric heating concepts. The partners’ techno-economic assessment showed that both concepts offer comparable energy efficiency, while each provides specific characteristics depending on feedstock, operating mode and integration conditions. For this reason, both were selected for parallel industrial-scale demonstrations, enabling direct comparison under identical operating conditions.
The demonstration plant design is intended to validate continuous olefin production using electric heating and to serve as a reference for future commercial-scale deployments. The plant incorporates the following key features:
Two independent radiant boxes demonstrate the direct and indirect heating concepts.
Up to 6 MW of renewable electrical power can be drawn from the 6-kV grid to preheat feed and supply cracking duty.
The unit processes up to 4 tons per hour (tph) of naphtha, with cracked gas routed to an existing steam cracker for full commercial work-up.
The demonstration unit was intentionally designed to minimize scale-up risk. All key equipment, including the cracking coils and the heating elements, are of commercial dimensions.
The plant is configured for high operational flexibility, allowing both furnaces to run simultaneously or individually, while the other remains in standby, decoking or maintenance mode.
The authors’ company executed the EPC of the demonstration unit and is also responsible for licensing the technologyb to the market. Integration into an operating steam cracker imposed stringent requirements on EPC execution. All work had to comply with industrial safety, permitting and engineering standards for commercial production units. The authors’ company applied full industry-standard design reviews, documentation procedures and quality-control processes consistent with conventional large-scale process projects. In contrast to conventional fired furnaces, electric cracking imposes a significantly higher proportion of electrical components and interfaces, requiring tailored design methods and execution procedures. These included adapted computer-aided engineering (CAE) tools, customized hazard and operability (HAZOP) methodologies, new vendor qualification processes, revised acceptance and certification protocols, updated erection procedures and novel commissioning approaches. These key learnings from the EPC phase represent an invaluable asset, strengthening the capability to execute such projects and forming a solid foundation for future large-scale deployments.
The two electric cracking furnaces were inaugurated in April 2024 (FIG. 2).5,6 Since startup, the unit has accumulated several thousand hours of incident-free cracking operation.7,8
The results provide valuable insights into thermal performance, material behavior, operability and reliability under commercially relevant conditions (FIG. 3). Cracked gas compositions are in line with design expectations. For both concepts, the well-developed and robust heat and temperature control concepts enable homogenous temperature distribution without any hotspots. Automation concepts allow for fully remote, rapid start-up and change of operating conditions, executed from the control room without the need of any field operator action. The systems have proven to be reliable, robust and safe both in normal operation and in case of trip scenarios.
Relevant operating parameter variations, including heat flux profile tuning, feedstock composition, steam/hydrocarbon ratio and cracking severity have been investigated. The decoking procedure follows standard industry practice with steam-air mixtures, ensuring operational familiarity for plant personnel. Automated switch-over procedures between cracking and decoking were successfully demonstrated. Early involvement of shift personnel in technology development and comprehensive training were also key aspects. Operators have given positive feedback, and the furnaces and auxiliaries are easy to operate due to a high degree of automation. The operation is scheduled to continue to validate simulation models, as well as optimize the designb of large-capacity installations.
Commercial eFurnace design. The EPC activities for the commercial-scale eFurnace demonstration plant and its operation provide a unique opportunity to generate a detailed, first-of-a-kind experience with large-scale electric cracking technology, both regarding design and operation.
Along with the EPC and operation of the commercial-scale eFurnace demonstration plant, the design of large-capacity installations has been fully developed for both heating concepts.8 Each concept incorporates a scalable architecture optimized for operability, maintainability, power distribution and integration into new and existing steam cracker layouts (FIG. 4). The following sections outline selected elements of the large-capacity furnace design and illustrate some key scale-up considerations.
Radiant box design: Indirect heating. For the indirect heating concept, a scalable and modular radiant box design was developed to provide a flexible and reliable platform for large-capacity commercial installations in a single box. The fundamental design of the radiant box results from the arrangement of the heating elements on heating modules along the radiant box walls. Key boundary conditions include the required process heat duty, electrical characteristics such as supply voltage and grid connection, and the selection of heating element materials tailored to service temperature, lifetime and mechanical considerations. Operability and controllability further influence the configuration of the heating modules and create the basis for a highly responsive heating system.
These factors result in a modular radiant box design, where the smallest independently controlled unit is referred to as an electrical unit cell. Each electrical unit cell comprises several structural unit cells that ensure mechanical integrity via vertical and horizontal support structures. Multiple heating modules are mounted within each structural unit cell, forming a repeatable and scalable pattern across the radiant box walls. This modular concept enables flexible heat distribution, simplified maintenance and straightforward capacity scale-up, enabling single radiation chambers even for large-capacity installations.
Since the indirect concept enables an independent design of heating elements and process tubes, conventional coil designs can be used without modification. This enables the application of all existing cracking coil types and geometries as per operators’ preferences.
Advanced multi-physics modeling has been essential for optimizing the thermal behavior of the radiant box. These models combine fluid dynamics, reaction kinetics, radiant heat transfer and coil performance. Validated directly against the commercial-scale demonstration unit’s operating data, the simulations were used to refine the heat distribution strategy. Rather than applying uniform heat load across all elements, the optimized configuration adopts the duty across the furnace zones to achieve more uniform heating-element temperatures (FIG. 5). This reduces thermal loads, extends heating-element life and minimizes maintenance needs. The same models can be applied to allow operators to identify the most efficient set points for maximizing product yields.
Radiant box design: Direct heating. The direct heating concept uses the cracking coils as both process tubes and resistive heating elements. Conventional coil materials are applied, combined with an optimized proprietary coil geometry. As in conventional cracking furnace designs, the coil is configured in multiple segments connected by return bends. The proprietary coil design further incorporates a special electrical “star-connection” across the coil segments, which enables safe, uniform heat release along the entire length of the coil.
Unlike conventional furnaces—or indirectly heated electric furnace designs—the hottest region in the radiant box is the coil surface itself, not the surrounding refractory or heating elements. This fundamental difference reduces overall radiant box temperatures and contributes to significantly longer component lifetimes.
Simulations of volumetric heat release confirmed a highly uniform resistive heating along the coil length. However, the net heat flux into the process fluid varies: it is roughly 40% higher at the inlet and 40% lower near the outlet of the cracking coils, which is caused by the increasing gas temperature and the resulting increasing coil surface temperature from inlet to outlet (FIG. 6). This beneficial heat flux redistribution results from intra-coil radiative exchange within the radiant box and provides a desired heat-input profile for cracking reactions, which benefits from higher heat flux at the inlet sections of the cracking coils.
Feed and heat integration. Electrification eliminates flue-gas generation, removing the need for a conventional convection section and providing a substantially wider range of heat-integration options. A flexible heat integration toolbox was developed that accommodates different feedstocks, steam requirements and renewable power supply profiles. Across all configurations, feed and dilution steam are initially preheated using low-temperature heat sources before being directed to the furnace vicinity, where electric preheaters and superheaters provide the required inlet temperatures.
Various quench and heat-recovery schemes—ranging from steam generation with a single transfer line exchanger to multi-step arrangements incorporating feed-effluent exchangers—enable the fine-tuning of steam production and electrical demand. Depending on site-specific constraints, these schemes can reduce power consumption, enhance energy efficiency or expand feedstock flexibility. The most advanced variant under development employs a high-temperature feed-effluent exchanger for minimal electrical power usage while maintaining high operability.5
The resulting flexibility surpasses that of conventional furnaces and allows operation across the full spectrum of cracker feedstocks—from ethane to heavy liquids, as well as bio-feeds and pyrolysis oils.
Power supply concept. Because commercial eFurnaces require transformation from medium/high voltage (typically from 6 kV–150 kV) to low voltage (< 1 kV), several power-supply architectures were evaluated, including static transformers, variable transformers, thyristor power controllers, rectifiers and step transformers. Each was assessed for capital and operational expenditures (CAPEX/OPEX), controllability, grid interaction and robustness. The most favorable configurations are being implemented and thoroughly tested in the commercial-scale demonstration unit, while future large-capacity installations will be adapted to the site’s electrical characteristics and available power supply—incorporating the lessons-learned from the commercial-scale demonstration.
General arrangement. Large-scale furnace layout follows an advantageous stacking of the heat-integration sections above the radiant box. Electrical control equipment—medium- and low-voltage systems—can be arranged adjacent to or beneath the furnace depending on plot constraints. Maintenance considerations are embedded into the design, including, for example, dedicated openings for recoiling, access corridors for heating-module servicing (indirect design) and pull-spaces for conventional heat exchangers and electric heaters (FIG. 7).
The flexible general arrangement options ensure that the eFurnace can be integrated into both new and existing steam cracker footprints with minimal site disruption.
With scale-up work now completed, the underlying technology principles have matured into designs suitable for large-capacity steam-cracking applications, and the authors’ company is in the position to offer front-end engineering design (FEED) and EPC execution of large-capacity eFurnace projects.
Broader industrial application. Both heating principles have demonstrated excellent performance in the industrial-scale demonstration plant. The consortiuma intends to advance commercialization of both approaches, as each offers distinct advantages even within the relatively narrow field of steam cracking. Beyond this core application, both concepts also show strong potential for deployment across a wide range of high-temperature industrial heating processes.
The indirect heating concept effectively fills a technology gap for medium-high temperature applications in the range of approximately 400°C–900°C (752°F–1,652°F) (process temperatures). In this segment, conventional electric circulation heaters—whether insulated or open wire—may be impractical due to limitations in robustness, scale, operability or maintainability. The electrically heated radiant-box configuration of the indirect concept offers a compelling alternative. Potential applications include, for example, process gas heaters for the steel industry, ethylene dichloride furnaces, refinery heaters and other thermal units requiring stable, controllable heat input at elevated temperatures.
The direct heating concept is particularly well suited for processes requiring temperatures significantly above 600°C (1,112°F). Many of these applications also allow for relatively long heating tubes, which further enhances the competitiveness of the direct heating concept. Under such conditions, the proprietary configuration of the directly heated process tubes delivers strong advantages across all major design criteria—robustness, scale, thermal efficiency, plot area, operational flexibility and lifetime—and finally delivers unmatched total cost of ownership. Applications include, for example, high-temperature gas heaters used in the cement and steel industries, as well as other gas heating applications transitioning away from fuel-fired technologies.
Given this broad potential, the authors’ company is actively engaging with stakeholders across multiple energy-intensive industries to explore adoption opportunities and jointly shape pathways for large-scale decarbonization through electrified high-temperature process heating.
Takeaway. The industrial-scale demonstration of electric steam cracking marks a decisive step towards emissions reduction of petrochemical operations. By validating both the direct and indirect resistive-heating concepts under commercial conditions, the project demonstrates that electric furnaces can reliably deliver the high temperatures, tight control and operational flexibility required for steam cracking while eliminating the CO2 emissions associated with fuel firing. The experience collected during EPC and operations has fostered the development of mature, scalable large-capacity eFurnace designs that integrate efficiently into existing cracker layouts and can accommodate a wide spectrum of feedstocks and other design constraints.
Beyond steam cracking, the two heating concepts provide a versatile platform for broader industrial electrification. Their adaptability to other applications positions them as strong enablers of high-temperature process heating electrification and decarbonization. With engineering and design work now complete, commercial deployment is ready to proceed, offering industry a practical and future-proof pathway to low-carbon, electrically heated operation. HP
NOTES
Linde, BASF and SABIC collaboratively developed the electric cracking furnace technology
STARBRIDGE™ electric furnace
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Torben Hoefel has > 14 yrs of professional experience in olefin technologies. He has worked as a Process Engineer in leading roles, contributing to the development and design of new olefin plants, as well as the revamp of existing ones. In his current role in Product Management for Sustainable Olefin Technologies, Dr. Hoefel is passionate about driving technological innovations and implementing solutions that support organizations and societies in achieving their ambitious decarbonization goals.
Martin Hofstaetter earned an MS degree in energy and process engineering from the Technical University of Munich and joined Linde Engineering in 2014. With > 11 yrs of experience in olefin technologies, he specializes in large olefin plant furnaces, working on new designs, complex revamp projects and startups. Since 2018, Hofstaetter has been closely involved in the development of the electric cracking furnace, contributing as technology implementation manager and co-inventor of several related patents.
Felix Roessler earned his PhD working on a cooperation between Linde Engineering and the Chair of Plant and Process Technology of the Technical University of Munich, focusing on the flexible operation and demand side management of large-scale process plants. The main field of research was the development of digital twins of process plants. In 2021, Dr. Roessler joined Linde Engineering as a Process Engineer, working on the design and revamp of large-scale ethylene plants. He focuses on the electrification of ethylene plants in general and is a core member of the technical team developing Linde’s eFurnace technology for commercial-scale electrical heating.
Matthias Mayerhofer is a Product Manager at Linde Engineering since 2015, focusing on development, IP management and sustainability. Since 2021, Dr. Mayerhofer has led electrification efforts and was Technology Implementation Manager for the eFurnace project from the Selas-Lindes side. When he joined Linde in 2013, he was a Process Engineer designing refinery heaters, waste heat recovery units and waste incinerators. Dr. Mayerhofer earned a PhD in engineering in the field of biomass gasification, and a Diploma in mechanical engineering, both from the Technical University of Munich.
Gunther Kracker is the Executive Director of Conceptual Design for Large Projects at Linde Engineering. After joining Linde in 2004 as a Process Engineer for petrochemical plants, Dr. Kracker subsequently moved through various management roles and responsibilities for different disciplines and technology fields. Today, Dr. Kracker oversees the conceptual design of Linde’s petrochemical, natural gas, and H2 and syngas technologies.