New electrification technology converts high-emission metal heat treatment into a carbon-free process

Researchers at the Korea Institute of Energy Research (KIER), led by Dr. Hookyung Lee, have developed an electrified heat treatment technology that replaces fossil fuels with electricity in the metal heat treatment process used in galvanized steel-strip production for automobiles and household appliances. The technology is expected to be broadly applicable across energy-intensive industries such as steelmaking, supporting decarbonization of industrial processes.

The government has recently accelerated efforts to decarbonize industrial processes, including process electrification, in pursuit of the national greenhouse gas reduction targets for 2035. As a result, energy-intensive industries such as steel are under increasing pressure to adopt electrified heating technologies.

* Industrial sector emission reduction target: achieving up to a 31% reduction from 2018 levels by decarbonizing feedstocks and fuels, electrifying industrial processes, and scaling up the production of low-carbon products, as announced at the 5th Plenary Meeting of the Presidential Committee on Carbon Neutrality and Green Growth (November 2025).

Galvanized steel-strips are produced through a continuous galvanizing line (CGL, Continuous Galvanizing Line) process, in which steel plates are continuously fed through a molten zinc bath for coating. During this process, the steel-strips undergo annealing, a heat treatment step involving controlled heating and cooling, to enhance ductility and formability for subsequent processing.

Heat for the annealing furnace is conventionally supplied by burning fossil fuels such as natural gas. As a result, the process inevitably emits large amounts of greenhouse gases, including carbon dioxide and nitrogen oxides. In fact, carbon dioxide emissions from the steel industry including zinc manufacturing processes account for approximately 15% of Korea’s total national emissions.

To address this challenge, the research team developed a “carbon-free annealing system” that operates solely on electricity by replacing the burners of conventional combustion-based annealing furnaces with electric heating elements. When tested under conditions closely resembling commercial production processes, the technology successfully reduced concentrations of carbon dioxide and nitrogen oxides in exhaust gases by more than 98%.

The core of the newly developed system lies in its furnace design technology. The research team retained the refractory structure and steel-strip conveying mechanism of conventional combustion-based annealing furnaces, while replacing burners with electric heating elements installed on both the upper and lower sections of the furnace. In addition, by precisely designing the distance between the heating elements and the steel-strip, the system enables rapid and uniform heating through high-temperature radiant heat while minimizing heat loss to the furnace walls.

When the developed system was applied to anneal steel-strips with a thickness of 0.49 millimeters at 750°C, the results confirmed that the color, microstructure, and mechanical properties of the steel-strips were equivalent to those achieved using conventional combustion-based annealing furnaces. In contrast, emissions of carbon dioxide and nitrogen oxides were reduced by more than 98% compared to combustion-based processes. These results demonstrate that, with appropriate equipment design and operating conditions, carbon emissions can be significantly reduced while maintaining the same level of productivity and product quality.

In particular, the electric annealing furnace can operate without the fuel and air supply systems, burners, and exhaust systems required for conventional combustion-based furnaces, reducing capital investment costs and installation footprint by approximately 40%. Moreover, when powered by renewable electricity such as wind and solar energy, the system can enable a truly carbon-free heat treatment process, making it highly effective in addressing global environmental regulations, including carbon border adjustment mechanisms.

* Carbon Border Adjustment Mechanism (CBAM): A policy that imposes and collects an additional carbon price on products produced outside the EU when they are imported into the EU, ensuring that the carbon cost is equivalent to that paid for products manufactured within the EU.

Dr. Hookyung Lee, the principal researcher of the study, stated, “This demonstration is the world’s first case to show that carbon-free heating can be achieved simply by replacing burners with electric heating elements.” He added, “Moving forward, we plan to expand the technology into an AI-based design and operation system that automatically recommends optimal heating-element configurations based on steel-strip width, thickness, and conveying speed, ultimately developing it into an export-ready carbon-free heating solution linked to commercial-scale demonstrations with domestic steelmakers and overseas markets.”

The results of this study were published in September 2025 in Applied Thermal Engineering (IF 6.9), a globally recognized journal in energy and thermal engineering. The research was supported by Korea’s Ministry of Trade, Industry and Energy, and the demonstration was carried out at the facilities of Samwoo Eco Co., Ltd., in collaboration with the industry partner.