Preface to the Special Issue on “Innovation for Ironmaking Systems Combined with Low-Carbon, Material Recycle and Energy Saving Technologies”

Study

The Intergovernmental Panel on Climate Change (IPCC) insisted on the importance of limiting global warming to 2.0°C in its Fifth Assessment in 2014. Then, the report “Global warming of 1.5°C”, IPCC, in 2018 reported as “Global warming is likely to reach 1.5°C between 2030 and 2052.”, “There are limits to adaptation and adaptive capacity for some human and natural systems at global warming of 1.5°C”, and “In model pathways with overshoot of 1.5°C, … global net anthropogenic CO₂ emissions decline by about 45% from 2010 levels by 2030, reaching net zero around 2050”. Requirement to CO₂ emission mitigation becomes more tightly even in the last four years. Therefore, there is an urgent need for the mitigation of anthropogenic CO₂ emissions. The ironmaking industry emits over 12% of the total CO₂ emissions in Japan; thus, a low-carbon ironmaking process is vitally important. This special issue was planned in order to showcase innovative solutions for the establishment of a low-carbon ironmaking process.

The pathways for the realization of low-carbon industrial processes are as follows:

(i) Efficient utilization of fossil resources.

(ii) Switching from fossil resources to non-fossil resources for primary energy.

(iii) Recycling carbon materials from CO₂.

(iv) Recycling iron materials from used iron products for raw material saving and comprehensive CO₂ emission reduction.

The Japanese ironmaking industry has devoted a great amount of effort toward an efficient utilization of fossil resources over the last few decades; their ironmaking process has now become one of the most efficient processes in the world. Although, CO₂ emission mitigation is an important development for the realization of a sustainable society, yet, carbon materials have long been a vital part of our lives and switching to alternative materials might be difficult. Carbon will still be required in the future. For innovative reductions in CO₂ emissions, a shift of the primary energy source is needed along with the simultaneous recycling of carbon materials for conventional industrial processes and societies. To establish sustainable carbon usage in a low-carbon society, an active carbon recycling energy system (ACRES) was proposed (Kato, ISIJ Int’l, 2010). Subsequently, the application of the ACRES concept to ironmaking process was studied as a smart ironmaking process, iACRES, in the iACRES research group organized at the Iron Steel Institute of Japan (ISIJ) during the 2011–2013 fiscal years. Based on the results of iACRES research group, the new concept Sustainable Iron and Steel Making System based on Material Recycling Technologies (SMART system) was proposed. The SMART system configuration is shown in Fig. 1. The unique feature of SMART system is the reduction in CO₂ emissions through the introduction of non-fossil energies for carbon and iron material recycling. Then SMART system research group was operated in ISIJ during 2015–2017 FY. The 18 members, from 7 universities and 7 industrial organizations, participated actively. The objectives given by the research group were as follows:

(1) System analysis of SMART system.

(2) CO₂ reduction for carbon recycling.

(3) Ironmaking processes with material recycling under SMART system.

Fig. 1.

Schematic of the SMART system.

Given the lack of previous research on SMART system-based processes, the group set their own research base for the development of SMART system. CO₂ reduction processes were examined using solid oxide electrolysis and polymer electrolyte electrolysis. CO₂ emission reduction and iron material recycling processes and technologies in the iron and steel making processes were demonstrated experimentally and thermodynamically including tramp-element removal, carburizing melting behavior analysis and hydrogen phenomenon on ironmaking process. Effect of SMART system on low-carbon ironmaking system was evaluated system process analysis by using results of the group researches. The candidates for the alternative primary energy were renewable energy and the high-temperature gas cooled reactor, which is capable of producing temperatures up to 950°C. The group members verified the technicalities of the SMART system; this special issue aims to integrate the results and innovation of this research. The conclusions of the study demonstrated that SMART system is capable of drastically reducing the CO₂ emissions and raw material consumption from the ironmaking process, when compared with other low-carbon process proposals. It is effective in diminishing the burden of carbon capture and storage for the mitigation of CO₂ emissions, and is one of the pathways for a sustainable ironmaking process.

I would like to express my deep appreciation to Prof. Hiroshi Nogami (Tohoku University), Prof. Takao Nakagaki (Waseda Univ.), Prof. Ichiro Yamanaka (Tokyo Tech), Dr. Ko-ichiro Ohno (Kyushu Univ.) for their dedication to the special issue as the editorial board members, and to the members of the SMART system research group and their supporters for their wonderful contributions to the issue and the establishment of the SMART system concept.

I sincerely hope that the SMART system will contribute to the establishment of a low-carbon society for the future generations.