Introduction

The global iron and steel industry contributes approximately 7 % to total global greenhouse gas emissions, making it the highest among of all heavy industry sectors [1]. Ferrous metallurgy is an energy-intensive industry [2; 3], with energy costs accounting for a significant portion of steel production costs – from 20 to 40 % [4]. Therefore, many strategies for decarbonization of steel production involve energy conservation. Thus, the iron and steel industry significantly contributes to global greenhouse gas (GHG) emissions and, consequently, climate change.

In the Russian Federation, there is an urgent need for scientific research to reduce the carbon footprint of the iron and steel industry, taking into account regional differences. This issue is of particular importance, given that Western expert studies [5] have unjustifiably reported a high environmental impact for Russian industry and high per capita carbon emissions (three times higher than the global average), and these emissions are on the rise1. Greening production increases the resilience of enterprises, which is crucial in the context of unprecedented sanctions affecting the development patterns of the iron and steel industry.

This paper examines existing technologies and practices for decarbonization of iron and steel production and their implementation status as of early 2025. It also analyzes the potential for scaling up these technologies and the challenges that need to be overcome.

Existing technological innovations and examples of their implementation

In May 2021, the International Energy Agency (IEA) released a report [6], which was updated in 2023 [7]. This report proposed a path for the global energy sector to help achieve the goal of the Paris Agreement which is to limit the global temperature increase to 1.5 °C above pre-industrial levels and keep it below 2 °C. Although this document provided important guidance for policymakers, industry, and the financial sector, the target of the Paris Agreement was not met in 2024 according to the EU’s Copernicus Climate Change Service (C3S)2. The International Energy Agency proposes so-called near zero emission projects ‒ projects that have close to zero emissions from the outset after commissioning (Fig. 1).

According to IEA recommendations, it is planned that by 2050, the share of iron and steel production will account for 95 % of the total volume, as a result of implementing such projects (Table).

The simplest solution to reducing emissions is the use of scrap metal (EAF) and the introduction of clean electricity to replace fossil fuels. However, this method is limited by the availability of high-quality scrap. Innovative technologies such as carbon capture, use, and storage (CCUS), electrolytic hydrogen-based direct reduction iron (EHB DRI), and iron ore electrolysis (IOE) are the keys to reducing emissions, but they remain very expensive and are mostly at the pilot stage.

Carbon Capture, Use, and Storage (CCUS) technologies

CCUS technologies are implemented very slowly worldwide due to their high cost. When implemented in iron and steel production, they are among the most expensive compared to other industries3 [8; 9]. However, the IEA insists that the lack of such technologies cannot help achieving zero emissions targets. In the iron and steel industry, CCUS technologies have proven to be the least expensive low-carbon options compared to other technologies. It is believed that upgrading existing facilities using CCUS (Carbon Capture, Utilization, and Storage) is more cost-effective than building new facilities using alternative technologies. The main challenge is that steelmaking does not produce pure carbon dioxide. When iron is smelted in a blast furnace using coal coke, the resulting blast furnace gas contains 12 – 20 % CO2 , 20 – 30 %  CO, up to 0.5 % CH4 , 1 – 4 % H2 , and 55 – 58 % N2 [10]. Flue gases also contain carbon monoxide and nitrogen oxides. The first CCUS projects in the iron and steel industry have already been launched. Since 2016, a commercial CO2 capture project has been operating in Abu Dhabi (UAE) at a steel plant with a capacity of 0.8 million tones CO2 per year. The gas is sent to oil production facilities to improve the efficiency of oil recovery. In 2022, PJSC Severstal was mentioned as actively developing CCUS in the iron and steel industry4. The innovative HIsarna iron production technology, developed under the Ultra-Low CO2 Steel (ULCOS) program [11] by Tata Steel Europe, allows simplifying the capture of carbon dioxide. Recent pilot tests of HIsarna have successfully demonstrated a reduction in CO2 emissions [12]. Other benefits of the HIsarna process include the ability to use low-grade iron ore and a variety of fuels (from thermal coal and gas fuels to biomass) instead of coking coal, as well as the ease of capturing most CO2 . The HIsarna process involves partial pre-reducing iron ore pellets in the upper section of the BOF (CCF) and iron smelting in the lower section of the smelting reduction vessel (SRV) using the HIsmelt technology. Developers believe that the HIsarna technology has good potential as an alternative to blast furnace production.

One variation of CCUS technology is CO2 capture in mineral systems, which results in the formation of carbonate compounds. Industrial waste, including slags, is alternative mineral feedstock. Carbonation can be achieved using both direct and indirect methods (Fig. 2).

According to the recent estimates [13; 14], nearly a half of the direct reduction in CO2 emissions can be attributed to the mineralization of steel slag. Steel slag was originally considered as waste and disposed of in landfills. However, efforts are underway to redirect some types of slag from landfills to use as environmentally friendly binders and quarry aggregates [15 – 21]. The research has shown that carbonization of steel slag improves its properties making it more durable and chemically active [22; 23]. These developments are promising for future applications such as the production of road surfaces, cement, and concrete products [24 – 26].

However, the potential of CO2 mineralization has been questioned due to the high energy costs needed to overcome slow reaction kinetics. Although studies in this area are still in their early stages, they already have significant scientific and practical implications, especially due to the current need to achieve carbon neutrality.

Technologies based on the electrolytic production of hydrogen and its use in direct reduction

The first steel produced using direct reduction hydrogen technologies was developed in 2021 by the Swedish company SSAB under the Swedish HYBRIT 5 (Hydrogen Breakthrough Ironmaking Technology) project. As the direct reduction technology based on “green” hydrogen holds great promise and has the potential to revolutionize the iron and steel industry, it requires significant R&D investment to bring it to scale. Only the first HYBRIT pilot projects are underway followed by large-scale demonstration projects with a capacity of 1.3 Mt and then full commercialization by 2030 – 2040. Notably, “green” electrification of the industry requires access to significant amounts of electricity from renewable sources. Thus, fossil-free steel production in the HYBRIT project will annually require approximately 10 – 15 TWh of electricity [27]. A similar technology is being developed by ArcelorMittal in Germany. Under the HyBit (Hydrogen for Bremen’s industrial transform) project, the installation of hydrogen electrolyzers began at the Bremen steelworks in October 2024. The Bremen steelworks annually emits approximately 4.6 million tones CO2 , making it the seventh-largest polluting industrial plant in Germany [28]. The transition to hydrogen technologies aims to improve this situation.

In Russia, recent studies have also explored the feasibility of hydrogen production using electrolysis. This involves generating electricity from wind power plants and then using it in the industrial process of direct iron ore reduction to produce “green” steel [29]. The prospects for developing hydrogen technologies in the domestic iron and steel industry are being explored [30; 31].

Notably, the transition to the use of “green” hydrogen occurs under significant uncertainty. Hydrogen has not yet been widely adopted or integrated into specific energy policies, and there are no clear details or conditions regarding the distribution of public funds to facilitate the transition to hydrogen. It is important to understand that by 2050, in Europe alone, the production of decarbonized steel based on hydrogen obtained through electrolysis will increase the electricity demand for the iron and steel industry by approximately 11 % (or 183 TWh). In the context of decarbonization, this demand should be met by increasing the production of “clean energy” from wind and solar sources [29].

Iron ore electrolysis technologies

The transition to a low-carbon economy requires changes in iron and steel production methods. Two electrolysis approaches are currently being explored. The first one is the ULCOWIN electrolysis process (ULCOS project) when iron ore grains are suspended in an alkaline sodium hydroxide solution at 110 °C resulting in a solid iron product [33]. A pilot plant with a capacity of 5 kg of iron per day has been proposed [34]. Second, iron production through molten iron oxide electrolysis [35] is a new technology developed by the Massachusetts Institute of Technology (MIT), for which laboratory research has been completed. This process produces iron that is completely carbon-free. The gas component produces only oxygen, not carbon dioxide. Molten oxide electrolysis, in which iron ore is dissolved in a mixed oxide solvent (such as silica or calcium oxide), occurs at a temperature of approximately 1600 °C. The resulting molten iron is collected at the bottom of the cell and pumped out. Since electrolysis produces no CO2 , the process could theoretically be considered carbon-neutral, but only if the electricity required to power the process is generated with zero CO2 emissions. There are several engineering challenges that need to be addressed before electrolysis becomes economically viable.

Conclusions

Overall, various projects are underway globally to develop and implement the low-CO2 steelmaking technologies. Potential significant reductions in greenhouse gas emissions in the iron and steel industry are constrained by current technologies, the quality of iron ore raw materials, and the availability of low-carbon fuels, hydrogen, and zero-carbon energy. The decarbonization of the iron and steel industry will be impossible without new innovation-intensive technologies, without maximizing the potential of secondary energy resources at ironworks, and without introducing renewable energy sources. The CCUS industry in Russia is still in its early stages, but the current climate agenda clearly encourages the Russian companies to consider this decarbonization method.